Kyushu University Academic Staff Educational and Research Activities Database
Researcher information (To researchers) Need Help? How to update
Keiko Sasaki Last modified date:2020.10.26

Professor / Resources System Engineering
Department of Earth Resources Engineering
Faculty of Engineering


Graduate School
Undergraduate School
Other Organization


E-Mail *Since the e-mail address is not displayed in Internet Explorer, please use another web browser:Google Chrome, safari.
Homepage
https://kyushu-u.pure.elsevier.com/en/persons/keiko-sasaki
 Reseacher Profiling Tool Kyushu University Pure
http://process.mine.kyushu-u.ac.jp/index.html
Phone
092-802-3338
Fax
092-802-3338
Academic Degree
PhD. (Eng.)
Country of degree conferring institution (Overseas)
No
Field of Specialization
Environmental Materials, Geomimetics, Environmental Remediation, Biohydrometallurgy
Total Priod of education and research career in the foreign country
00years06months
Research
Research Interests
  • Synthesis and characterization of metal organic frameworks (MOFs) as adsorbents of anionic species in aqueous sphere
    keyword : MOFs
    2017.04~2020.03.
  • Biotreatment of carbonaceous refractory gold ore using cell free spent fungal medium and thermophilic iron-oxidizing microorganism
    keyword : carbonaceous refractory gold ore
    2015.10~2020.03.
  • Immobilization mechanism of anionic pollutant release from fly ash in cement by Ca additives.

    keyword : fly ash, cement, anionic pollutants, dissolution
    2017.04~2020.03.
  • Innovation of Novel Adsorbents Derived from Geomimetics for Burying of Radionuclides
    keyword : Radionuclides, adsorbent, geomimetics
    2016.04~2019.03.
  • Co-precipitation of borate, selenite and fluoride with hydroxyapatite using domestic calcium minerals
    keyword : Co-precipitation, borate, selenite, fluoride, hydroxyapatite
    2012.04~2019.03.
  • Syntheisis of layered double hydrooxides and their modification by organic pillars for adsorbents of anionic species
    keyword : layered double hydrooxides, adsorbents of anionic species,
    2011.02~2019.03.
  • Synthesis and characterization of lithium ion-sieve produced from Mn-oxidizing microorganisms
    keyword : Mn-oxidizing microorganisms, lithium ion sieve
    2010.04~2018.03.
  • Microbially mediated formation of arsenate using thermophiles
    keyword : Microbially mediated formation of arsenate, thermophiles
    2010.05~2011.03.
  • Separation of selenate from sulfate in aqueous process
    keyword : sulfate, selenate, separation
    2010.05~2011.03.
  • Bioleaching of arsenic-bearing copper ores using thermophilic iron-oxidizing microorganisms
    keyword : Bioleaching 、 arsenic-bearing copper ores 、 thermophilic iron-oxidizing microorganisms
    2008.04~2013.03.
  • Barrier materials from waste materials for radionuclides
    keyword : radionuclides, hydroxyapatite, animal bone materials, ion-exchange
    2009.04~2012.03.
  • Synthesis and regeneration of reactive matrials for removal of inorganic contaminants which are difficult to immbilize
    keyword : fluoride, borate, metal oxides, bi-metal oxides, layered double hydroxides
    2007.04~2013.03.
  • Remediation of contaminants in grondwaters by permeable reactive barries
    keyword : permeable reactive barries, groundwaters, contaminants, remediation
    2003.03A series of permeable reactive barriers (PRBs), which is a in situ ground water remediation technique, has been performed from aspects of remediation efficiency, remeditation expectation, remediation mechanisms. Until now, selenate, arsenate, heavy metals, fluoride, borate have been investigated as targets in groundwaters. Especially PRBs for fluoride and borate have been not yet officially reported in a full scale. Our PRB researches for fluoride and borate are intensely focused on development of novel reactive materials, long term column experiments in a laboratorial scale for years, and modeling. The project has been anually extended to collaborate with other institutes. .
  • Bioremediation using manganese-oxidizing microorganisms
    keyword : manganese-oxidizing microorganisms, biomineralization, nano pores, environmental remediation, bioremediation
    2001.04Several types of Mn-oxidizing microorganisms with significantly high Mn-oxidizing activity have been isolated from Mn-depositing environments, and characterized by phylogenetic methods. The biogenic Mn oxides showed morphologically, mineralogically and chemically unique properties, which are not common in synthetic Mn oxides. It was discovered that the biogenic Mn oxides can be applied as effective sorbents for selective sorption of rare metals. The properties are in progress investigated to extend to the application for separation among other rare earth elements..
Current and Past Project
  • From Waste Management to Bone Replacement: Synthesis and Functionally-Related Properties of Hydroxyapatite
Academic Activities
Books
1. Keiko Sasaki, Kojo Twum Konadu, "Biotechnological approaches to facilitate gold recovery from double refractory gold ores" in "Biotechnology in Mining and Metallurgical Industry" edited by Prof. Hongbo Zhao, Intech Open, 2020.10.
2. Paulmanickam Koilraj, Keiko Sasaki, 2D/2D graphene oxide-layered double hydroxide nanocomposite for the immobilization of different radionuclides, Wiley, 2020.09.
3. Binglin Guo, Keiko Sasaki, Low Carbon Stabilization and Solidification (S/S) of Hazardous Wastes, Elsevier, 2020.09.
4. N. Muthuchamy, S. Karthikeyan, Kang Hyun Park, Keiko Sasaki, Adam F. Lee, Nanoscale Materials with Different Dimensions for Advanced Electrocatalysts, , Elsevier, in press, 2020.02.
5. Keiko Sasaki, Qianqian Yu, Manganese oxides in Environments, American Chemical Society Symposium Series, 2014.11.
6. Keiko Sasaki, Microbiology for Minerals, Metals, Materials and Environment, CRC Press/ Taylor and Francis.
Reports
1. Sasaki Keiko, Spectroscopic study on bioleaching of enargite using thermophile, in “Microbiology for Minerals, Metals, Materials and Environment”, Edited by Abhilash, B. D. Pandey, K. A. Natarajan, CRC Press/Taylor and Francis, ISBN-978-1-4822-5729-8, Cat. No.K24089, 2014.10.
2. Investigation of Groundwater Remediation by Permeable Reactive Barriers in North America.
Papers
1. Binglin Guo, Quanzhi Tian, Tsubasa Oji, Lei Wang, Daniel C.W. Tsang, Keiko Sasaki,, Hydroxylated calcined dolomite as an effective and sustainable substitute of lime to precipitate as ettringite for treatment of selenite/selenate contaminated wastewater, Colloids Surf., A, in press., 2020.07.
2. Li Zhang, Srinivasarao Kanchela, Keiko Sasaki, Synthesis and characterization of imidazole-bearing polymer modified montmorillonite for adsorption of perchlorate, Appl. Clay Sci., in press, 2020.07.
3. Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima; Hajime Miki; Keiko Sasaki, Bubble interactions with chalcopyrite and molybdenite surfaces in seawater, Minerals Engineering, https://doi.org/10.1016/j.mineng.2020.106536, 157, 106536, 2020.07.
4. Keishi Oyama, Kazuhiko Shimada, Jun-ichiro Ishibashi, Keiko Sasaki, Hajime Miki, Naoko Okibe,, Catalytic mechanism of activated carbon-assisted bioleaching of enargite concentrate, Hydrometallurgy , doi.org/10.1016/j.hyc!romet.2020.105417, 196, 105417, 2020.07.
5. Keiko Sasaki, Yoshikazu Hayashi, Takeshi Nakamura, Binglin Guo, Quanzhi Tian, Stabilization of borate by hot isostatic pressing after co-precipitation with hydroxyapatite using MAP, Chemosphere, 10.1016/j.chemosphere.2020.126860, 254, 2020.09, Boric acid is one of the most mobile inorganic contaminant species in nature due to its pKa of 9.23. Co-precipitation of borate with hydroxyapatite (HAp: Ca5(PO4)3OH) facilitates the simultaneous removal of borate with co-existing oxoanions in natural waters. The cost of phosphate is an impediment to industrialize the co-precipitation of borate with HAp for treatment of geothermal waters. In the present work, an inexpensive industrial by-product of magnesium ammonium phosphate (MAP) derived from sewage sludge, was examined as a phosphate source. MAP includes 89% pure magnesium ammonium phosphate, resulting in better performance than the pure chemical form of NH4H2PO4, because Mg2+ and Al3+ (trace elements in MAP product) play roles in enhancing the removal rate of borate and lowering the equilibrium borate concentration. These ions have a good affinity with phosphate to nucleate crystal seeds independently of powdery Ca sources. To reduce the bulky volume of solid residues, hot isostatic pressing (HIP) was applied. There is structural water in HAp; therefore, the greatest volume reduction was achieved with 78.3 ± 2.0% (n = 3). Additionally, a synergic effect to suppress the released borate, greater than the sequential combination of calcination and cold isostatic pressing was accomplished in the toxicity contents leaching procedure (TCLP) test. This is not due to larger crystal sizes alone, but it is derived from boron stabilization in HAp at an atomic level by the synergic effect of heating and pressing simultaneously..
6. Ahmad T. Yuliansyah, · Satoshi Kumagai, · Tsuyoshi Hirajima, · Keiko Sasaki, Production of valuable chemicals from oil palm biomass using hot‑compressed water method, J. Mater. Cycles Waste Manage., https://doi.org/10.1007/s10163-020-01073-8, in press, 2020.07.
7. Quanzhi Tian, Binglin Guo, Keiko Sasaki, Influence of silicate on the structural memory effect of layered double hydroxides for the immobilization of selenium, Journal of Hazardous Materials, 10.1016/j.jhazmat.2020.122674, 395, 2020.08, The influence of silicate on the structural memory effect of layered double hydroxides (LDHs) has been rarely reported. In this study, five kinds of calcined LDHs (CLDHs) were synthesized and used as adsorbents for the sorption of selenium with or without silicate, under the initial pH 10 and 13, respectively, characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectroscopy (IR), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and N2 adsorption-desorption isotherm. The results indicated that silicate can significantly affect the phase transformation of CLDHs, and the sorption amounts of selenite and selenate dramatically decreased in the presence of silicate. Specifically, silicate can react with MgO and Al2O3 in CLDHs to generate magnesium silicate hydrate and geopolymer-like substance which were covered on the surface of particles, blocking the hydroxylation of metal oxides. However, higher pH suppressed the interaction between MgO and silicate and enhanced the formation of geopolymer-like substance, which promoted the regeneration of LDHs. Al in CLDHs plays a critical role in the regeneration of LDHs. Besides, the ternary oxides (CLDH-2, Mg2Al0.75Fe0.25-oxide; CLDH-3, Mg2Al0.5Fe0.5-oxide) possessed larger specific surface areas (127.7 and 158.2 m2/g) and consequently presented more resistance to the effect of silicate..
8. Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, Hajime Miki, Keiko Sasaki, Shigeto Kuroiwa, Yuji Aoki, Effect of H2O2 and potassium amyl xanthate on separation of enargite and tennantite from chalcopyrite and bornite using flotation, Minerals Engineering, 10.1016/j.mineng.2020.106371, 152, 2020.06, Effect of oxidation treatment using hydrogen peroxide (H2O2) on the floatability of copper sulfide minerals (i.e., chalcopyrite and bornite) and arsenic-bearing copper minerals (i.e., tennantite and enargite) is reported in this study. Pure mineral flotation shows that the floatability of each mineral significantly decreases after the oxidation treatment. Interestingly, flotation of mixed mineral of copper sulfide and arsenic-bearing copper minerals shows that enargite and tennantite exhibit a higher floatability compared to chalcopyrite and bornite after the oxidation treatment followed by the addition of potassium amyl xanthate (PAX). These flotation results indicate a possibility for selective flotation of copper sulfide and arsenic-bearing copper minerals. Indeed, bench-scale flotation tests show that the oxidation treatment using H2O2 and the addition of PAX can deliver a satisfying separation of copper sulfide and arsenic-bearing copper minerals. Difference oxidation products (i.e., CuO, Cu(OH)2, CuSO4, FeOOH, and Fe2(SO4)3) on each mineral surface are likely the cause of this different flotation behavior. Furthermore, these oxidation products may affect the adsorption amount of PAX on each mineral. Indeed, the adsorption tests show that PAX is adsorbed more on tennantite, bornite, and enargite compared to chalcopyrite owing to the formation of CuSO4 and Cu(OH)2 on the mineral surfaces under oxidizing conditions. A possible mechanism is proposed in this study to explain the selective flotation behavior of mixed minerals..
9. Quanzhi Tian, Binglin Guo, Chitiphon Chuaicham, Keiko Sasaki, Mechanism analysis of selenium (VI) immobilization using alkaline-earth metal oxides and ferrous salt, Chemosphere, 10.1016/j.chemosphere.2020.126123, 248, 2020.06, The immobilization of selenate (SeO42–) using metal oxides (CaO and MgO) and ferrous salt as the immobilization reagents were examined by the leaching test and solid-phase analysis via XRD, XAFS, TGA, and XPS. The results indicated that nearly all of SeO42– was reduced to SeO32– in the CaO-based reaction within 7 days. Then, the generated SeO32– was mainly sorbed onto the iron-based minerals (Fe2O3 and FeOOH) through the formation of both bidentate mononuclear edge-sharing (1E) and monodentate mononuclear corner-sharing (1V) inner-sphere surface complexes, suggested by PHREEQC simulation and EXAFS analysis. Differently, less amount of SeO42– (approximately 45.50%) was reduced to SeO32– for the MgO-based reaction. However, if the curing time increases to a longer time (more than 7 days), the further reduction could occur because there are still Fe(II) species in the matrix. As for the associations of Se in the solid residue, most of the selenium (SeO32– and SeO42–) was preferentially distributed onto the Mg(OH)2 through outer-sphere adsorption. Definitely, this research can provide a deep understanding of the immobilization of selenium using alkaline-earth metal oxide related materials and ferrous substances..
10. Subbaiah Muthu Prabhu, Keiko Sasaki, S. SD Elanchezhiyan, G. Paruthimal Kalaignan, Chang Min Park, Self-tuning tetragonal zirconia-based bimetallic nano(hydr)oxides as superior and recyclable adsorbents in arsenic-tolerant environment
Template-free in and ex situ synthetic methods, stability, and mechanisms, Chemical Engineering Journal, 10.1016/j.cej.2020.124573, 390, 2020.06, In this study, we aimed to decorate nano-ZrO2 on LaOx to enhance the architectural stability of LaOx for the uptake of both arsenate and arsenite in single solutions. LaOx was obtained as lanthanum methanoate (LaMe) from a simple solvothermal reaction of lanthanum and benzoic acid. The leaving group of formic acid was used as a reducing agent to grow ZrO2 over LaOx, which resulted in a nanocomposite denoted as ZrO2@x%LaMe. The de-arsenic behavior of this composite was compared with that of one-pot-synthesized La-ZrO2 and ZrO2@x%La(OH)3, with La(OH)3 being obtained commercially. Powder X-ray diffraction patterns showed that the ZrO2 structure was transformed from monoclinic to tetragonal during the formation of ZrO2@x%LaMe, La-ZrO2, and ZrO2@x%La(OH)3. Among the synthesized nano-bimetallic composites, ZrO2@50%LaMe exhibited the highest adsorption densities for both arsenate and arsenite due to the uniform distribution of ZrO2 over the LaOx surface resulted in a larger Brunauer–Emmett–Teller specific surface area and a higher zeta potential charge. The synthesized nanocomposites were reused several times with the aid of 0.1 M HNO3 for maximizing the uptake of both arsenate and arsenite from water. Selectivity and the stability (pH) studies indicated that the nanocomposites were highly selective and showed zero-dissolution behavior, respectively. The results of this study suggested that these nanocomposites could be used as alternatives for many La-based adsorbent materials in practical applications..
11. Binglin Guo, Yuta Kamura, Paulmanickam Koilraj, Keiko Sasaki, Co-sorption of Sr2+ and SeO42- as the Surrogate of Radionuclide by Alginate-encapsulated Graphene Oxide-Layered Double Hydroxide Beads, Environmental Research, in press., 2020.05.
12. Kojo T. Konadu, Kojo, Diego M. M. Flores, Ryotaro Sakai, Robert J. Huddy, Susan T. L. Harrison, Takashi Kaneta, Keiko Sasaki, Biological pretreatment of carbonaceous matter in double refractory gold ores: a review and some future considerations, Hydrometallurgy, accepted, 2020.05.
13. Quanzhi Tian, Binglin Guo, Keiko Sasaki, Addition of calcined hydrotalcite into geopolymer pastes activated by different alkaline solutions for immobilization of selenium: influence and mechanism analysis, J. Hazard. Mater., https://doi.org/10.1016/j.jhazmat.2019.121880, 387, 121994 , 2020.05.
14. Seonyi Namgung, Binglin Guo, Keiko Sasaki, Sang Soo Lee, Giehyeon Lee, Macroscopic and microscopic behaviors of Mn(II) (ad)sorption to goethite with the effects of dissolved carbonates under anoxic conditions, Geochimica et Cosmochimica Acta, 10.1016/j.gca.2020.03.036, 277, 300-319, 2020.05, Manganese and its compounds have been extensively studied because of their far-reaching roles in a wide range of biogeochemical processes in natural systems. The (ad)sorption behavior of Mn(II), however, is poorly understood despite its important role as the primary reaction step for surface-catalyzed Mn(II) oxidation that is the principal abiotic process forming various Mn (oxyhydr)oxides in nature. Here, we systematically examined Mn(II) (ad)sorption to one of the most common natural sorbents, goethite, in oxygen- and carbonate-free systems. Traditional sorption edge and isotherm experiments were conducted by varying sorbate-to-sorbent ratio (0.027–15 μmol∙m−2) and solution pH (pH 5.0–9.0). The effects of dissolved carbonates on Mn(II) sorption were also assessed in a range of naturally prevalent concentrations (0.5–10 mM NaHCO3). The Mn(II) uptake on goethite followed a typical Langmuir isotherm in the absence of dissolved carbonates, with increasing maximum adsorption capacities (Γmax) from 0.19 at pH 6.5 to 3.4 μmol∙m−2 at pH 9.0. The presence of dissolved carbonates raised the extent of Mn(II) adsorption, which appeared to be directly correspondent to that of the adsorption of dissolved carbonates. Extended X-ray absorption fine structure (EXAFS) analysis indicated that Mn(II) predominantly formed inner-sphere binuclear bidentate surface complexes. Mn(II) uptake became deviated from the Langmuir model and showed a clear indication of surface precipitation when the Mn(II) sorption density (Γ) exceeded a threshold value in a given solution composition. This secondary Mn(II) phase was identified as rhodochrosite using X-ray diffraction (XRD) and transmission electron microscope (TEM). Additionally, it would be plausible that a minor fraction of adsorbed Mn(II) coexisted with the secondary rhodochrosite according to a linear combination fitting (LCF) of the X-ray absorption near edge structure (XANES) spectra of Mn reference and samples. These systematic investigations of the macroscopic and microscopic behaviors of Mn(II) (ad)sorption to goethite provide a critical avenue for disentangling surface-catalytic Mn(II) oxidation processes, which ultimately lead to the formation of diverse Mn (oxyhydr)oxides in the environment..
15. Keiko Sasaki, Yoshikazu Hayashi, Takeshi Nakamura, Binglin Guo, Quanzhi Tian, Stabilization of borate by hot isostatic pressing after coprecipitation with hydroxyapatite using MAP, Chemosphere, in press, https://doi.org/10.1016/j.chemosphere.2020.126860, 2020.04.
16. Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima; Hajime Miki; Keiko Sasaki, Effect of H2O2 and potassium amyl xanthate on separation of enargite and tennantite from chalcopyrite and bornite using flotation, Minerals Engineering, in press, 2020.04.
17. Seonyi Namgung, Binglin Guo, Keiko Sasaki, Sang Soo Lee, Giehyeon Lee, Macroscopic and microscopic behaviors of Mn(II) (ad)sorption to goethite with the effects of dissolved carbonates under anoxic conditions , Geochimica et Cosmochimica Acta, https://doi.org/10.1016/j.gca.2020.03.036, 277, 300-319, 2020.04.
18. Chitiphon Chuaicham, Sekar Karthikeyan, Radheshyam R. Pawar, Yihuang Xiong, Ismaila Dabo, Bunsho Ohtani, Yoonyoung Kim, Jun Tae Song, Tatsumi Ishihara, Keiko Sasaki, Energy-resolved distribution of electron traps for O/S-doped carbon nitrides by reversed double-beam photoacoustic spectroscopy and the photocatalytic reduction of Cr(vi), Chemical Communications, 10.1039/c9cc09988c, 56, 26, 3793-3796, 2020.04, We report for the first time to our knowledge the identification of heteroatom-doped and undoped C3N4 with the energy-resolved distribution of electron traps (ERDT) near the conduction band bottom position (CBB) using reversed double-beam photoacoustic spectroscopy. The ERDT/CBB pattern is used to classify the type of elemental doping in C3N4, related to photocatalytic efficiency..
19. Quanzhi Tian, Binglin Guo, Keiko Sasaki, Immobilization mechanism of Se oxyanions in geopolymer
Effects of alkaline activators and calcined hydrotalcite additive, Journal of Hazardous Materials, 10.1016/j.jhazmat.2019.121994, 387, 2020.04, Geopolymers have been widely adopted to stabilize the cationic pollutants. However, few studies have focused on the immobilization of anionic species. In this study, the immobilization of SeO32– and SeO42– was explored for the first time using geopolymer activated by different alkaline solutions (NaOH and Na2SiO3) with and without calcined hydrotalcite (CHT), characterized by TCLP, XRD, FTIR, TG, NMR, XAFS, and N2 adsorption-desorption isotherm. Na2SiO3-activated geopolymers without CHT additive showed lower leaching percentages of SeO32– and SeO42– (approximately 10 % and 18 %) than NaOH-activated geopolymers (approximately 58 % and 74 %). It has been proven that electrostatic interaction is the main association mode of SeO32– and SeO42– in both NaOH- and Na2SiO3-activated geopolymers. Hence, compactness plays a vital role in the Se leaching from geopolymer. The addition of CHT reduced the compactnesses of both NaOH- and Na2SiO3-geopolymers. Due to the formation of hydrotalcite, the CHT additive contributed to immobilize SeO32– and SeO42– in NaOH-activated geopolymers. However, this phenomenon was not observed in Na2SiO3-activated geopolymers. Thus, the leaching amount of Se greatly increased from Na2SiO3-activated geopolymers with CHT additive. This study provides new insights on the application of geopolymer to immobilize anionic pollutants..
20. Sekar Karthikeyan, Kassam Ahmed, Amin Osatiashtiani, Adam F. Lee, Karen Wilson, Keiko Sasaki, Ben Coulson, Will Swansborough-Aston, Richard E. Douthwaite, Wei Li, Pompon Dahlia-like Cu2O/rGO Nanostructures for Visible Light Photocatalytic H2 Production and 4-Chlorophenol Degradation, ChemCatChem, 10.1002/cctc.201902048, 12, 6, 1699-1709, 2020.03, Hierarchical Cu2O nanospheres with a Pompon Dahlia-like morphology were prepared by a one-pot synthesis employing electrostatic self-assembly. Nanocomposite analogues were also prepared in the presence of reduced graphene oxide (rGO). Photophysical properties of the hierarchical Cu2O nanospheres and Cu2O/rGO nanocomposite were determined, and their photocatalytic applications evaluated for photocatalytic 4-chlorophenol (4-CP) degradation and H2 production. Introduction of trace (<1 wt %) rGO improves the apparent quantum efficiency (AQE) at 475 nm of hierarchical Cu2O for H2 production from 2.23 % to 3.35 %, giving an increase of evolution rate from 234 μmol.g−1.h−1 to 352 μmol.g−1.h−1 respectively. The AQE for 4-CP degradation also increases from 52 % to 59 %, with the removal efficiency reaching 95 % of 10 ppm 4-CP within 1 h. Superior performance of the hierarchical Cu2O/rGO nanocomposite is attributable to increased visible light absorption, reflected in a greater photocurrent density. Excellent catalyst photostability for >6 h continuous reaction is observed..
21. Chitiphon Chuaicham, Radheshyam Rama Pawar, Sekar Karthikeyen, Bunsho Ohtani , Keiko Sasaki, Fabrication and characterization of ternary sepiolite/g-C3N4/Pd composites for improvement of photocatalytic degradation of ciprofloxacin under visible light irradiation, Journal of Colloid and Interface Science, in press, 2020.02.
22. Ryotaro Sakai, Kojo T. Konadu, Diego M.M. Flores, Susan H. L. Harrison, Keiko Sasaki, Effect of carbonaceous matter on bioleaching of Cu from chalcopyrite ore, Hydrometallurgy, 2020.02.
23. Subbaiah Muthu Prabhu, Keiko Sasaki, S.S D. Elanchezhiyan, G. Paruthimal Kalaignan, Self-tuning tetragonal zirconia-based bimetallic nano(hydr)oxides as superior and recyclable adsorbents in arsenic-tolerant environment: Template-free in and ex situ synthetic methods, stability, and mechanisms, Chemical Engineering Journal, 2020.02.
24. Wuhui Luo, Qidong Huang, Philip Antwi, Binglin Guo, Keiko Sasaki, Synergistic effect of ClO4− and Sr2+ adsorption on alginate-encapsulated organo-montmorillonite beads: Implication for radionuclide immobilization, Journal of Colloid and Interface Science, 560, 2020, 338-348, 2020.02.
25. Quanzhi Tian, Binglin Guo, Chitiphon Chuaicham, Keiko Sasaki, Mechanism analysis of selenium (VI) immobilization using alkalineearth metal oxides and ferrous salt, Chemosphere, https://doi.org/10.1016/j.chemosphere.2020.126123, 248, 126123, 2020.02.
26. Chitiphon Chuaicham, Sekar Karthikeyan, Jun Tae Song, Tatsumi Ishihara, Bunsho Ohtani, Keiko Sasaki, Importance of ZnTiO3 Phase in ZnTi-Mixed Metal Oxide Photocatalysts Derived from Layered Double Hydroxide, ACS Applied Materials and Interfaces, 10.1021/acsami.9b18785, 12, 8, 9169-9180, 2020.02, In this study, ZnTi-mixed metal oxides (ZTM), such as ZnTiO3, were synthesized from ZnTi layered double hydroxides by varying the molar ratio of Zn/Ti, calcination temperatures, and synthesis methods (hydrothermal or reflux). The surface electronic characteristics of ZTM were investigated by the energy-resolved distribution of electron traps (ERDTs) using reversed double-beam photoacoustic spectroscopy. The ZTM samples obtained by conducting hydrothermal synthesis at 500 °C showed similar ERDT patterns independent of the molar ratio of Zn/Ti, although ZnTiO3 phase was not observed in the X-ray diffraction pattern, when the Zn/Ti ratio was high. When the ERDT patterns demonstrated a high electron accumulation level near the conduction band bottom in hydrothermal products at 500 °C, a higher photocatalytic phenol degradation efficiency was observed due to the formation of ZnTiO3 phase. This suggested that the product with the high Zn/Ti molar ratio (Zn/Ti = 6) constituted amorphous ZnTiO3.The enhanced photocatalytic performance of ZTM could be attributed to the heterojunction of electrons among ZnO, TiO2, and ZnTiO3, which enabled electron transfer in the composites, prevented charge recombination, and promoted a wider visible light adsorption by ZnTiO3 phase irrespective of its crystallinity..
27. Wuhui Luo, Qidong Huang, Philip Antwi, Binglin Guo, Keiko Sasaki, Synergistic effect of ClO4 and Sr2+ adsorption on alginate-encapsulated organo-montmorillonite beads
Implication for radionuclide immobilization, Journal of Colloid And Interface Science, 10.1016/j.jcis.2019.10.049, 560, 338-348, 2020.02, Perchlorate (ClO4 ) and pertechnetate (TcO4 ) exhibit similar adsorption characteristics on alkyl quaternary ammonium-modified montmorillonite (Mt), and 99mTcO4 normally coexists with 90Sr2+ in radionuclide-contaminated water. In this study, hexadecyl pyridinium (HDPy)-modified Mt (OMt) was encapsulated in alginate beads to inhibit HDPy release and simultaneously immobilize ClO4 and Sr2+ ions. The release of HDPy was remarkably reduced (78 times) from OMt after alginate encapsulation. Adsorption of ClO4 and Sr2+ on the obtained composite demonstrated synergistic effects, with adsorption capacities reaching 0.542 and 0.484 mmol/g, respectively. Compared to the single-adsorbate system, adsorption capacities of ClO4 and Sr2+ increased significantly. The characterization of solids using X-ray diffraction, Fourier transform infrared spectroscopy, 13C nuclear magnetic resonance, and X-ray photoelectron spectroscopy, as well as the chemical analysis of the aqueous solution, demonstrated that HDPy+–COO disintegration accounted for the adsorption synergy. HDPy was extracted from the Mt interlayer space during the synthesis of OMt/alginate and then partially re-intercalated back after interacting with ClO4 during the adsorption of ClO4 and/or Sr2+. In the binary-adsorbate system, the synergy-induced adsorption capacity was superior to many previously reported adsorbents, implying that OMt/alginate beads can be a promising adsorbent for the remediation of aqueous solutions contaminated with multiple radionuclides..
28. Quanzhi Tian, Binglin Guo, Keiko Sasaki, Immobilization mechanism of Se oxyanions in geopolymer: Effects of alkaline activators and calcined hydrotalcite additive, J. Hazard. Mater., doi.org/10.1016/j.jhazmat.2019.121994 , 2020.01.
29. Chitiphon Chuaicham, Radheshyam R Pawar, Karthikeyen Sekar, Yihuang Xiong, Ismaila Dabo, Bunsho Ohtani, Keiko Sasaki, Energy-resolved distribution of electron traps for O/S-doped carbon nitrides by reversed double-beam photoacoustic spectroscopy and the photocatalytic reduction of Cr(VI), Chemical Communications, in press., 2020.01.
30. Chitiphon Chuaicham, Sekar Karthikeyen, Jun Tae Song, Tatsumi Ishihara, Bunsho Ohtani, Keiko Sasaki, Importance of ZnTiO3 phase in ZnTi-mixed metal oxide photocatalysts derived from layered double hydroxide, ACS Applied Materials & Interfaces, in press., https://doi.org/10.1021/acsami.9b18785, 2019.12.
31. Sekar Karthikeyan,Kassam Ahmed, Amin Osatiashtiani, Adam F. Lee, Karen Wilson, Keiko Sasaki, Ben Coulson, Will Swansborough-Aston, Richard E. Douthwaite, and Wei Li, Pompon Dahlia-like Cu2O/rGO nanostructures for visible light photocatalytic H2 production and 4-chlorophenol degradation, Chem Cat Chem, doi.org/10.1002/cctc.201902048, in press, 2019.12, Hierarchical Cu2O nanospheres with a Pompon Dahlia-like
morphology were prepared by a one-pot synthesis employing
electrostatic self-assembly. Nanocomposite analogues were also
prepared in the presence of reduced graphene oxide (rGO).
Photophysical properties of the hierarchical Cu2O nanospheres and
Cu2O/rGO nanocomposite were determined, and their photocatalytic
applications evaluated for photocatalytic 4-chlorophenol (4-CP)
degradation and H2 production. Introduction of trace (<1 wt%) rGO
improves the apparent quantum efficiency (AQE) at 475 nm of
hierarchical Cu2O for H2 production from 2.23 % to 3.35 %, giving an
increase of evolution rate from 234 μmol.g-1.h-1 to 352 μmol.g-1.h-1
respectively. The AQE for 4-CP degradation also increases from 52 %
to 59 %, with the removal efficiency reaching 95 % of 10 ppm 4-CP
within 1 h. Superior performance of the hierarchical Cu2O/rGO
nanocomposite is attributable to increased visible light absorption,
reflected in a greater photocurrent density. Excellent catalyst
photostability for >6 h continuous reaction is observed.
.
32. Sekar Karthikeyan, Chitiphon Chuaicham, Radheshyam R. Pawar, Keiko Sasaki, Wei Li, Adam F. Lee and Karen Wilson, Template free mild hydrothermal synthesis of core–shell Cu2O(Cu)@CuO visible light photocatalysts for N-acetyl-para-aminophenol degradation, Journal of Materials Chemistry A, 10.1039/c9ta07009e, 20737-20777, 7, 2019.12.
33. Quanzhi Tian, K. Sasaki, A novel composite of layered double hydroxide/geopolymer for co-immobilization of Cs+ and SeO4 2− from aqueous solution, Science of the Total Environment, 10.1016/j.scitotenv.2019.133799, 695, 2019.12, Geopolymers are always considered as promising materials for the treatment of radioactive wastes. In order to extend the application of geopolymer to the immobilization of anionic species, a novel composite of layered double hydroxide/geopolymer (LDH/GEO) was synthesized and applied for cosorption of Cs+ and SeO4 2−. The ability of LDH/GEO to sorb Cs+ was maintained as that of pure GEO, even though the surface of geopolymer was homogeneously covered by the LDH platelets. The sorption of Cs+ onto LDH/GEO composite occurred via ion exchange, which was controlled by particle diffusion. It is different with Cs+ sorption onto pure GEO governed by film diffusion. Therefore, “Pocket diffusion” was proposed for the particle diffusion as the case of LDH/GEO because this kind of diffusion would be restricted in a certain distance around the ring entrance gate due to the amorphous essence of GEO. For SeO4 2− sorption by LDH/GEO, ion-exchange with the interlayer NO3 and surface sorption could be the main mechanisms. Importantly, the sorption speed of SeO4 2− achieved by LDH/GEO composite was much faster than that by pure LDH. In the binary system (Cs++ SeO4 2−), the sorption of Cs+ was slightly suppressed compared to the single system, which might be due to the formation of ion-pair complex of [CsSeO4]. However, it did not have negative effect on the SeO4 2− sorption. In the presence of other cations or anions, the cosorption performances of Cs+ and SeO4 2− were satisfactorily obtained. Furthermore, the Cs+ and SeO4 2- sorption densities were superior to the previously reported values. The combined MgAl-LDH/geopolymer composite could be a promising material for the immobilization of Cs+ and SeO4 2−, and this work would provide guidance for the development of geopolymer-based materials for environmental applications..
34. Shuang Xu; Jiawen Zhao; Qianqian Yu; Xinhong Qiu; Keiko Sasaki, Understanding how specific functional groups in humic acid affect the sorption mechanisms of different calcinated layered double hydroxides
, Chemical Engineering Journal, in press, 2019.11.
35. Shuang Xu, Jiawen Zhao, Qianqian Yu, Xinhong Qiu, Keiko Sasaki, Structure memory effect of layered double hydroxides in the presence of modeled aromatic compounds to natural organic matter, ACS Earth Space Chemistry, 2019.10.
36. Binglin Guo, Yihuang Xiong, Weinan Chen, Sarah A. Saslow, Naofumi Kozai, Toshihiko Ohnuki, Ismaila Dabo, Keiko Sasaki, Spectroscopic and First-Principles Investigations of Iodine Species Incorporation into Ettringite: Implications for Iodine Migration in Cement Waste Forms, J. Hazard. Mater., 10.1016/j.jhazmat.2019.121880, in press, 2019.10.
37. Paulmanickam Koilraj, Rajathsing Kalusulingam, Keiko Sasaki, Arginine and lysine-functionalized layered double hydroxides as efficient sorbents for radioactive Co2+ removal by chelate-facilitated immobilization, Chemical Engineering Journal, 10.1016/j.cej.2019.05.166, 359-369, 2019.10, An increase in heavy metal contamination in aquatic environments require an efficient sorbent for the removal and reuse of toxic elements. We attempted to synthesize arginine/lysine-functionalized MgAl LDHs in one-pot without using any hazardous alkaline reagents. The LDHs produced at lower temperatures showed larger numbers of amino acids on their surfaces, while these are exchanged with CO32− at higher temperatures. The arginine/lysine present on the surface of LDH enhanced the adsorption of Co2+ and showed the highest adsorption capacity of 1.159 and 1.170 mmol/g for the LDHs functionalized with lysine and arginine, respectively. Kinetics studies indicated that the adsorption of Co2+ occurred by multiple mechanisms. The Co2+ adsorption on these amino acid functionalized LDHs occurs by the formation chelation complex with amino acid, which provide better vicinity of Co2+ to basic LDH that facilitating the enhanced immobilization. The sorption of other divalent metal ions on these arginine/lysine functionalized LDHs followed the order of Co2+ > Ni2+ > Mn2+ > Fe3+. The Co2+ forms diamine-like coordination that is stable on the surface of LDH and causes higher sorption densities, while other metals form partial glycine-like coordination that detaches the amino acid from the surface of LDH, thereby leading to lesser sorption capacity. The conversion of anionic LDH in to a cationic sorbent was successfully fabricated by these arginine/lysine-assisted methods and explored for the remediation of Co2+ from aqueous solution..
38. Quanzhi Tian, Shingo Nakama, Keiko Sasaki, Immobilization of cesium in fly ash-silica fume based geopolymers with different Si/Al molar ratios, Science of the Total Environment, 10.1016/j.scitotenv.2019.06.095, 687, 1127-1137, 2019.10, Geopolymers are considered as promising matrixes for waste solidification. However, the effects of the Si/Al molar ratio of geopolymer on the immobilization efficiencies for metal ions have not been fully studied and understood. In the present study, geopolymers with different Si/Al ratios were synthesized from coal fly ash and silica fume. Adsorption tests were conducted to evaluate their immobilization efficiencies for Cs+. The results indicated that geopolymer with low Si/Al ratio could have a better immobilization performance for Cs+ than that with high Si/Al ratio. High Si/Al ratio could contribute to a more compact structure of geopolymer. Each sorption process fitted better with the pseudo-second-order model, and all of them were governed by film diffusion. However, the diffusion mode was gradually closed to particle diffusion with the increase in the Si/Al ratio. Both Langmuir and Freundlich models could well fit the sorption data, and the free energy of each sorption process decreased with the increase in the Si/Al ratio according to D-R equation. The distribution of AlO4 tetrahedron in the geopolymer structure plays a significant role in the immobilization of Cs+. Low Si/Al ratio could result in that more AlO4 tetrahedrons distribute in the small rings (+. However, high Si/Al ratio leads to the distribution of AlO4 tetrahedrons mainly in larger rings (≥eight-member), and this could contribute to the high leaching amount of Cs+. In addition, high-temperature treatment could contribute to the formation of nepheline or pollucite in geopolymer matrix. These minerals locked Cs+ in their structures, and the leaching amount of Cs+ was reduced correspondingly from high levels (26.36%, 27.26%, and 66.92%) to very low levels (0.67%, 0.53%, and 0.95%)..
39. Paulmanickam Koilraj, Rajathsing Kalusulingam, Keiko Sasaki, Arginine and lysine-functionalized layered double hydroxides as efficient sorbents for radioactive Co2+ removal by chelate-facilitated immobilization, Chemical Engineering Journal, 10.1016/j.cej.2019.05.166, 359-369, 2019.10, An increase in heavy metal contamination in aquatic environments require an efficient sorbent for the removal and reuse of toxic elements. We attempted to synthesize arginine/lysine-functionalized MgAl LDHs in one-pot without using any hazardous alkaline reagents. The LDHs produced at lower temperatures showed larger numbers of amino acids on their surfaces, while these are exchanged with CO32− at higher temperatures. The arginine/lysine present on the surface of LDH enhanced the adsorption of Co2+ and showed the highest adsorption capacity of 1.159 and 1.170 mmol/g for the LDHs functionalized with lysine and arginine, respectively. Kinetics studies indicated that the adsorption of Co2+ occurred by multiple mechanisms. The Co2+ adsorption on these amino acid functionalized LDHs occurs by the formation chelation complex with amino acid, which provide better vicinity of Co2+ to basic LDH that facilitating the enhanced immobilization. The sorption of other divalent metal ions on these arginine/lysine functionalized LDHs followed the order of Co2+ > Ni2+ > Mn2+ > Fe3+. The Co2+ forms diamine-like coordination that is stable on the surface of LDH and causes higher sorption densities, while other metals form partial glycine-like coordination that detaches the amino acid from the surface of LDH, thereby leading to lesser sorption capacity. The conversion of anionic LDH in to a cationic sorbent was successfully fabricated by these arginine/lysine-assisted methods and explored for the remediation of Co2+ from aqueous solution..
40. Quanzhi Tian, Shingo Nakama, Keiko Sasaki, Immobilization of cesium in fly ash-silica fume based geopolymers with different Si/Al molar ratios, Science of the Total Environment, 10.1016/j.scitotenv.2019.06.095, 687, 1127-1137, 2019.10, Geopolymers are considered as promising matrixes for waste solidification. However, the effects of the Si/Al molar ratio of geopolymer on the immobilization efficiencies for metal ions have not been fully studied and understood. In the present study, geopolymers with different Si/Al ratios were synthesized from coal fly ash and silica fume. Adsorption tests were conducted to evaluate their immobilization efficiencies for Cs+. The results indicated that geopolymer with low Si/Al ratio could have a better immobilization performance for Cs+ than that with high Si/Al ratio. High Si/Al ratio could contribute to a more compact structure of geopolymer. Each sorption process fitted better with the pseudo-second-order model, and all of them were governed by film diffusion. However, the diffusion mode was gradually closed to particle diffusion with the increase in the Si/Al ratio. Both Langmuir and Freundlich models could well fit the sorption data, and the free energy of each sorption process decreased with the increase in the Si/Al ratio according to D-R equation. The distribution of AlO4 tetrahedron in the geopolymer structure plays a significant role in the immobilization of Cs+. Low Si/Al ratio could result in that more AlO4 tetrahedrons distribute in the small rings (+. However, high Si/Al ratio leads to the distribution of AlO4 tetrahedrons mainly in larger rings (≥eight-member), and this could contribute to the high leaching amount of Cs+. In addition, high-temperature treatment could contribute to the formation of nepheline or pollucite in geopolymer matrix. These minerals locked Cs+ in their structures, and the leaching amount of Cs+ was reduced correspondingly from high levels (26.36%, 27.26%, and 66.92%) to very low levels (0.67%, 0.53%, and 0.95%)..
41. Paulmanickam Koilraj, Rajathsing Kalusulingam, Keiko Sasaki, Arginine and lysine-functionalized layered double hydroxides as efficient sorbents for radioactive Co2+ removal by chelate-facilitated immobilization, Chemical Engineering Journal, 10.1016/j.cej.2019.05.166, 359-369, 2019.10, An increase in heavy metal contamination in aquatic environments require an efficient sorbent for the removal and reuse of toxic elements. We attempted to synthesize arginine/lysine-functionalized MgAl LDHs in one-pot without using any hazardous alkaline reagents. The LDHs produced at lower temperatures showed larger numbers of amino acids on their surfaces, while these are exchanged with CO32− at higher temperatures. The arginine/lysine present on the surface of LDH enhanced the adsorption of Co2+ and showed the highest adsorption capacity of 1.159 and 1.170 mmol/g for the LDHs functionalized with lysine and arginine, respectively. Kinetics studies indicated that the adsorption of Co2+ occurred by multiple mechanisms. The Co2+ adsorption on these amino acid functionalized LDHs occurs by the formation chelation complex with amino acid, which provide better vicinity of Co2+ to basic LDH that facilitating the enhanced immobilization. The sorption of other divalent metal ions on these arginine/lysine functionalized LDHs followed the order of Co2+ > Ni2+ > Mn2+ > Fe3+. The Co2+ forms diamine-like coordination that is stable on the surface of LDH and causes higher sorption densities, while other metals form partial glycine-like coordination that detaches the amino acid from the surface of LDH, thereby leading to lesser sorption capacity. The conversion of anionic LDH in to a cationic sorbent was successfully fabricated by these arginine/lysine-assisted methods and explored for the remediation of Co2+ from aqueous solution..
42. Quanzhi Tian, Shingo Nakama, Keiko Sasaki, Immobilization of cesium in fly ash-silica fume based geopolymers with different Si/Al molar ratios, Science of the Total Environment, 10.1016/j.scitotenv.2019.06.095, 687, 1127-1137, 2019.10, Geopolymers are considered as promising matrixes for waste solidification. However, the effects of the Si/Al molar ratio of geopolymer on the immobilization efficiencies for metal ions have not been fully studied and understood. In the present study, geopolymers with different Si/Al ratios were synthesized from coal fly ash and silica fume. Adsorption tests were conducted to evaluate their immobilization efficiencies for Cs+. The results indicated that geopolymer with low Si/Al ratio could have a better immobilization performance for Cs+ than that with high Si/Al ratio. High Si/Al ratio could contribute to a more compact structure of geopolymer. Each sorption process fitted better with the pseudo-second-order model, and all of them were governed by film diffusion. However, the diffusion mode was gradually closed to particle diffusion with the increase in the Si/Al ratio. Both Langmuir and Freundlich models could well fit the sorption data, and the free energy of each sorption process decreased with the increase in the Si/Al ratio according to D-R equation. The distribution of AlO4 tetrahedron in the geopolymer structure plays a significant role in the immobilization of Cs+. Low Si/Al ratio could result in that more AlO4 tetrahedrons distribute in the small rings (+. However, high Si/Al ratio leads to the distribution of AlO4 tetrahedrons mainly in larger rings (≥eight-member), and this could contribute to the high leaching amount of Cs+. In addition, high-temperature treatment could contribute to the formation of nepheline or pollucite in geopolymer matrix. These minerals locked Cs+ in their structures, and the leaching amount of Cs+ was reduced correspondingly from high levels (26.36%, 27.26%, and 66.92%) to very low levels (0.67%, 0.53%, and 0.95%)..
43. Paulmanickam Koilraj, Rajathsing Kalusulingam, Keiko Sasaki, Arginine and lysine-functionalized layered double hydroxides as efficient sorbents for radioactive Co2+ removal by chelate-facilitated immobilization, Chemical Engineering Journal, 10.1016/j.cej.2019.05.166, 359-369, 2019.10, An increase in heavy metal contamination in aquatic environments require an efficient sorbent for the removal and reuse of toxic elements. We attempted to synthesize arginine/lysine-functionalized MgAl LDHs in one-pot without using any hazardous alkaline reagents. The LDHs produced at lower temperatures showed larger numbers of amino acids on their surfaces, while these are exchanged with CO32− at higher temperatures. The arginine/lysine present on the surface of LDH enhanced the adsorption of Co2+ and showed the highest adsorption capacity of 1.159 and 1.170 mmol/g for the LDHs functionalized with lysine and arginine, respectively. Kinetics studies indicated that the adsorption of Co2+ occurred by multiple mechanisms. The Co2+ adsorption on these amino acid functionalized LDHs occurs by the formation chelation complex with amino acid, which provide better vicinity of Co2+ to basic LDH that facilitating the enhanced immobilization. The sorption of other divalent metal ions on these arginine/lysine functionalized LDHs followed the order of Co2+ > Ni2+ > Mn2+ > Fe3+. The Co2+ forms diamine-like coordination that is stable on the surface of LDH and causes higher sorption densities, while other metals form partial glycine-like coordination that detaches the amino acid from the surface of LDH, thereby leading to lesser sorption capacity. The conversion of anionic LDH in to a cationic sorbent was successfully fabricated by these arginine/lysine-assisted methods and explored for the remediation of Co2+ from aqueous solution..
44. Wuhui Luo, Qidong Huang, Philip Antwi, Binglin Guo, Keiko Sasaki, Synergistic effect of ClO4− and Sr2+ adsorption on alginate-encapsulated orga-no-montmorillonite beads: Implication for radionuclide immobilization, Journal of Colloid and Interface Science, doi.org/10.1016/j.jcis.2019.10.049, 2019.10.
45. Shuang Xu, Jiawen Zhao, Qianqian Yu, Xinhong Qiu, Keiko Sasaki, Effect of Natural Organic Matter Model Compounds on the Structure Memory Effect of Different Layered Double Hydroxides, ACS Earth and Space Chemistry, 10.1021/acsearthspacechem.9b00175, 3, 10, 2175-2189, 2019.10, The structural transformation of layered double hydroxides (LDHs) plays an important role in a variety of natural environmental behaviors. As one of the important ways of structure transformation in LDHs, the structure memory effect closely interacted with humic acid (HA). However, the role of functional groups in HA is unclear because its structure is relatively complex. Therefore, seven representative small molecules of single or double aromatic compounds were selected to explore their influence on the regeneration of different LDHs, thereby revealing key function groups in HA. As a result, ortho-benzene compounds could more effectively affect the regeneration of LDHs than other model compounds. For these compounds, the aliphatic chain length and aromatic ring size have little effect on regeneration of LDHs. However, increasing the number of carboxyl or hydroxyl groups affected the results, although all of them accelerated the regeneration rate of LDHs. Additionally, LDHs during the regeneration have a positive adsorption effect on both o-carboxyl and o-hydroxyl aromatic compounds; however, they have shown different effects on the regeneration of LDHs. Phthalic acid revealed no effect on the structure and crystallinity of regenerated LDH, while catechol inhibited the regeneration process and decreased the crystallinity of regenerated LDHs. The effects of o-hydroxyl aromatic compounds, such as catechol, are also dependent upon the type of LDHs. They have an inhibitory effect on the crystallinity of the regenerated Mg-LDH within a short time or with a high concentration but have no effect on its morphology. Although o-hydroxyl aromatic compounds have no effect on the crystallinity of regenerated Ca-LDH, the crystal growth was suppressed. This is due to the difference in the regeneration processes between two LDHs. These results provide a more detailed theoretical basis for understanding the influence of HA on the structural transformation of LDHs or even other minerals, such as hydroxides, in the environment..
46. Kojo T. Konadu, Susan T.L. Harrison, Kwadwo Osseo-Asare, Keiko Sasaki, Transformation of the carbonaceous matter in double refractory gold ore by crude lignin peroxidase released from the white-rot fungus, International Biodeterioration and Biodegradation, 10.1016/j.ibiod.2019.104735, 143, 2019.09, Sulfides and carbonaceous matter in double refractory gold ore (DRGO) were bio-treated sequentially using an iron-oxidizing archaeon Acidianus brierleyi followed by lignin peroxidase-dominating crude enzymes released from the white-rot fungus Phanerochaete chrysosporium to significantly improve gold recovery from 24% to 92%. Transformation of the carbonaceous matter in the sequential bio-treatment was interpreted with Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN), Raman spectroscopy and three-dimensional fluorescence spectrometry. Firstly, microbiological sulfide oxidation did not affect carbonaceous matter but decreased the arsenic content in the solid residue, facilitating the following enzymatic reaction. Next, the crude enzymes predominantly decomposed the defect-bearing graphitic carbon into humic-like substances. The humic-like substances were not completely soluble under pH 4 but were instead retained in the solid residue as a part of a newly formed carbonaceous aluminosilicate (C–Si–Al) phase. Due to a wide pKa range of humic-like substances, it is proposed that at pH 4, electrostatic interaction between humic substances and illite, with and without heavy metals, might have enabled the agglomeration of fine aluminosilicate particles. Some gold grains trapped in C–Si–Al agglomerates were released by the dissolution of humic-like substances in 1 M NaOH, resulting in a further increase in gold recovery of approximately 15%..
47. Karthikeyan Sekar; Chitiphon Chuaicham,; Radheshyam Pawar,; Keiko Sasaki, Wei Li, Adam Lee, Karen Wilson, Template free mild hydrothermal synthesis of core-shell Cu2O(Cu)@CuO visible light photocatalysts for N-acetyl-para-aminophenol degradation, J. Mater. Chem. A, 7, 20767-20777., 2019.09.
48. Sekar Karthikeyan, Chitiphon Chuaicham, Radheshyam R Pawar, Keiko Sasaki, Wei Li, Adam F. Lee, Karen Wilson, Template free mild hydrothermal fabrication of size-controlled core-shell CuO@Cu2O visible light photocatalyst, structural stability and their interfacial charge transfer mechanistic investigation, J. Material Chemistry A, 2019.08, Solar photocatalytic processes are a promising approach to environmental remediation, however their implementation requires improvements in visible light harvesting and conversion and a focus on low cost, Earth abundant materials. Semiconducting copper oxides are promising visible light photocatalysts for solar fuels and wastewater depollution. Here we report the mild, hydrothermal (template-free) synthesis of core-shell Cu2 0(Cu)@Cu0 photocatalytic architectures for the visible light photocatalytic degradation of N-acetyl-para-aminophenol (APAP). Hollow and rattle-like core-shell nanosphere aggregates with diameters between 200 nm and 2.5 µm formed under different synthesis conditions; all comprised an inner Cu2 0 shell, formed of 10-50 nm nanoparticles、surrounded by a protective corona of CuO nanoparticles. High reductant and structure-directing agent concentrations promoted the formation of a yolk-like Cu2 0/Cu core, associated with improved photophysical properties, notably a high oxidation potential and suppressed charge carrier recombination, that correlated with the highest apparent quantum efficiency (8%) and rate of APAP removal (7 µmol g―1 min―1). Trapping experiments demonstrated hydroxyl radicals were the primary active species responsible for APAP oxidation to quinones and short chain carboxylic acids. Rattle-like core-shell Cu2 0/Cu@Cu0 nanospheres exhibited excellent physiochemical stability and recyclability for APAP photocatalytic degradation.
49. Subbaiah Muthu Prabhu, Radheshyam Rama Pawar, Keiko Sasaki, Chang Min Park, A mechanistic investigation of highly stable nano ZrO 2 decorated nitrogen-rich azacytosine tethered graphene oxide-based dendrimer for the removal of arsenite from water, Chemical Engineering Journal, 10.1016/j.cej.2019.03.277, 1474-1484, 2019.08, We focused to synthesize graphene oxide-polyamidoamine dendrimer, up to 2nd generation, (GO-gen2) via a grafting method and the tethered groups were further covalently functionalized with a nitrogen-rich of an aromatic triazine ring of 5-azacytosine (Aza). Zirconia nanoparticles (ZrO 2 ) has been identified as promising material for removal of AsO 3 3− from water, however, its practical applicability is hindered due to its nanosize. Hence, ZrO 2 was successfully decorated through biomolecule assist on GO-gen2-Aza dendrimer. Various amounts of GO-gen2-Aza were used as stable supports to develop the nanocomposites with ZrO 2 . Then, the adsorption efficiency of highly toxic AsO 3 3− on developed composites was investigated for water treatment. The synthesized GO-dendrimer composites were characterized well before and after adsorption of AsO 3 3− using FTIR, PXRD, SEM, XPS, TGA, TEM and BET analysis. Particle size distribution of ZrO 2 revealed the peak top at 28 nm by zeta potential measurement. During synthesis, the GO sheets of composite were laminated by incorporation of ZrO 2 nanoparticles. The results of the batch experiments showed that ZrO 2 @2%GO-gen2-Aza dendrimer had higher adsorption density of AsO 3 3− than that of other developed forms of dendrimer composites. Langmuir equation well described the adsorption isotherm with the maximum adsorption capacity of 1.075 mmol/g. In addition, the enhanced AsO 3 3− adsorption density on ZrO 2 surface of ZrO 2 @x%GO-gen2-Aza, in which the GO-sheets were delaminated, resulting more ZrO 2 was dispersed homogeneously in the GO-sheets for maximum uptake of AsO 3 3− from water, confirmed by PXRD patterns. These results suggested that the developed GO-based dendrimer materials can be utilised for the practical remediation of toxic AsO 3 3− and other similar types of toxic ions, selenite, phosphate and fluoride from the contaminated water..
50. Quanzhi Tian, Keiko Sasaki, Application of fly ash-based materials for stabilization/solidification of cesium and strontium, Environmental Science and Pollution Research, 10.1007/s11356-019-05612-1, 26, 23, 23542-23554, 2019.08, Coal fly ash, as a solid waste produced from coal-fired power plants, was recycled for synthesis of zeolite A and geopolymer which were used for stabilization/solidification of Cs+ and Sr2+ from aqueous solutions. Specifically, the sorption data was successfully fitted by kinetic and thermodynamic models. The microstructure changes of zeolite A after loading Cs+ and Sr2+ were explored using XRD, FTIR, Raman, TG-DTA, and N2 adsorption/desorption isotherm. The solidification of the spent zeolites using geopolymer was conducted and evaluated. It was found that pseudo-second sorption mechanism was predominant and, according to the Boyd equation, film diffusion seemed to govern the sorption process. The maximum sorption capacities on Cs+ and Sr2+ based on Langmuir model were 2.12 and 1.93 mmol/g, respectively. During ion exchange with Cs+ and Sr2+, Cs+ was inclined to go through the window to occupy the position of eight-member ring, while the Sr2+ was more likely to replace the Na+ in the six-member ring, thereby easily leading to the different changes of zeolite structure. In addition, geopolymer could be a promising matrix for the treatment of radioactive waste because the leaching fraction greatly decreased after solidification by geopolymer. Therefore, the recycling of coal fly ash for radioactive waste disposal could achieve the concept of disposal waste with waste and recycling, which could greatly contribute to the sustainable development of society..
51. Subbaiah Muthu Prabhu, Radheshyam Rama Pawar, Keiko Sasaki, Chang Min Park, A mechanistic investigation of highly stable nano ZrO 2 decorated nitrogen-rich azacytosine tethered graphene oxide-based dendrimer for the removal of arsenite from water, Chemical Engineering Journal, 10.1016/j.cej.2019.03.277, 1474-1484, 2019.08, We focused to synthesize graphene oxide-polyamidoamine dendrimer, up to 2nd generation, (GO-gen2) via a grafting method and the tethered groups were further covalently functionalized with a nitrogen-rich of an aromatic triazine ring of 5-azacytosine (Aza). Zirconia nanoparticles (ZrO 2 ) has been identified as promising material for removal of AsO 3 3− from water, however, its practical applicability is hindered due to its nanosize. Hence, ZrO 2 was successfully decorated through biomolecule assist on GO-gen2-Aza dendrimer. Various amounts of GO-gen2-Aza were used as stable supports to develop the nanocomposites with ZrO 2 . Then, the adsorption efficiency of highly toxic AsO 3 3− on developed composites was investigated for water treatment. The synthesized GO-dendrimer composites were characterized well before and after adsorption of AsO 3 3− using FTIR, PXRD, SEM, XPS, TGA, TEM and BET analysis. Particle size distribution of ZrO 2 revealed the peak top at 28 nm by zeta potential measurement. During synthesis, the GO sheets of composite were laminated by incorporation of ZrO 2 nanoparticles. The results of the batch experiments showed that ZrO 2 @2%GO-gen2-Aza dendrimer had higher adsorption density of AsO 3 3− than that of other developed forms of dendrimer composites. Langmuir equation well described the adsorption isotherm with the maximum adsorption capacity of 1.075 mmol/g. In addition, the enhanced AsO 3 3− adsorption density on ZrO 2 surface of ZrO 2 @x%GO-gen2-Aza, in which the GO-sheets were delaminated, resulting more ZrO 2 was dispersed homogeneously in the GO-sheets for maximum uptake of AsO 3 3− from water, confirmed by PXRD patterns. These results suggested that the developed GO-based dendrimer materials can be utilised for the practical remediation of toxic AsO 3 3− and other similar types of toxic ions, selenite, phosphate and fluoride from the contaminated water..
52. Quanzhi Tian, Keiko Sasaki, Characterizations of calcium silicate hydrates derived from coal fly ash and their mechanisms for phosphate removal, Desalination and Water Treatment, 10.5004/dwt.2019.24135, 156, 78-86, 2019.07, Coal fly ash is an industrial waste generated from the thermal power plant and a large amount of it could be produced annually in the world, which can cause serious environmental problems. Reutilization of coal fly ash could be imperative to alleviate the environmental pressure. Thus, in the present study, coal fly ash was used as silicon source for the synthesis of calcium silicate hydrates (C-S-Hs) though the desilication process. Two kinds of C-S-Hs was synthetized at 100°C and room temperature respectively, with the fixed Ca/Si molar ratio of 1.2, and adopted as the adsorbents for phosphate. The properties of them were characterized using XRD, SEM, FTIR, TG-DTA as well as surface area and pore analysis. Compared to C-S-H synthesized from high temperature, the C-S-H obtained at room temperature possessed high purity and larger surface area. Therefore, synthesis by agitation at room temperature could be an alternative method to produce C-S-H materials from desilication liquid of coal fly ash, and this could save infrastructure cost and energy consumption. Both C-S-H materials have good ability to immobilize phosphate pollutant (higher than 100 mg·g–1). The specific mechanisms of phosphate removal using C-S-H include several steps: Firstly, phosphate ion was immobilized by binding with Ca2+and forming aggregates, and the C-S-H structures were gradually corroded. Eventually, hydroxyapatite was formed after the C-S-H structure was totally destroyed..
53. Kojo T. Konadu, Robert J. Huddy, Susan T.L. Harrison, Kwadwo Osseo-Asare, Keiko Sasaki, Sequential pretreatment of double refractory gold ore (DRGO)with a thermophilic iron oxidizing archeaon and fungal crude enzymes, Minerals Engineering, 10.1016/j.mineng.2019.04.043, 138, 86-94, 2019.07, Double refractory gold ore was sequentially pretreated to oxidize sulfides by thermophilic archaeon Acidianus brierleyi and then to decompose carbonaceous matters using the cell-free spent medium (CFSM)from white-rot fungus Phanerochaete chrysosporium. The pretreatment by A. brierleyi significantly improved the gold recovery from 25% to 77%. Additionally, the crude lignin-degrading enzymes in the CFSM converted the carbonaceous matters into more easily degradable substances, which were removed by alkaline washing, leading to a final gold recovery of 92%. These mineralogical alterations were confirmed by differential thermogravimetric analysis and quantitative evaluation of minerals with scanning electron microscopy. Based on the results, gold grains were mostly liberated after bio-oxidation of sulfides, and in following CFSM treatment, large particles of carbonaceous aluminosilicate were formed from the aggregation of clay minerals, gold grains and with partially decomposed carbonaceous matters acting as binders..
54. Quanzhi Tian, Keiko Sasaki, Characterizations of calcium silicate hydrates derived from coal fly ash and their mechanisms for phosphate removal, Desalination and Water Treatment, 10.5004/dwt.2019.24135, 156, 78-86, 2019.07, Coal fly ash is an industrial waste generated from the thermal power plant and a large amount of it could be produced annually in the world, which can cause serious environmental problems. Reutilization of coal fly ash could be imperative to alleviate the environmental pressure. Thus, in the present study, coal fly ash was used as silicon source for the synthesis of calcium silicate hydrates (C-S-Hs) though the desilication process. Two kinds of C-S-Hs was synthetized at 100°C and room temperature respectively, with the fixed Ca/Si molar ratio of 1.2, and adopted as the adsorbents for phosphate. The properties of them were characterized using XRD, SEM, FTIR, TG-DTA as well as surface area and pore analysis. Compared to C-S-H synthesized from high temperature, the C-S-H obtained at room temperature possessed high purity and larger surface area. Therefore, synthesis by agitation at room temperature could be an alternative method to produce C-S-H materials from desilication liquid of coal fly ash, and this could save infrastructure cost and energy consumption. Both C-S-H materials have good ability to immobilize phosphate pollutant (higher than 100 mg·g–1). The specific mechanisms of phosphate removal using C-S-H include several steps: Firstly, phosphate ion was immobilized by binding with Ca2+and forming aggregates, and the C-S-H structures were gradually corroded. Eventually, hydroxyapatite was formed after the C-S-H structure was totally destroyed..
55. Kojo T. Konadu, Robert J. Huddy, Susan T.L. Harrison, Kwadwo Osseo-Asare, Keiko Sasaki, Sequential pretreatment of double refractory gold ore (DRGO)with a thermophilic iron oxidizing archeaon and fungal crude enzymes, Minerals Engineering, 10.1016/j.mineng.2019.04.043, 138, 86-94, 2019.07, Double refractory gold ore was sequentially pretreated to oxidize sulfides by thermophilic archaeon Acidianus brierleyi and then to decompose carbonaceous matters using the cell-free spent medium (CFSM)from white-rot fungus Phanerochaete chrysosporium. The pretreatment by A. brierleyi significantly improved the gold recovery from 25% to 77%. Additionally, the crude lignin-degrading enzymes in the CFSM converted the carbonaceous matters into more easily degradable substances, which were removed by alkaline washing, leading to a final gold recovery of 92%. These mineralogical alterations were confirmed by differential thermogravimetric analysis and quantitative evaluation of minerals with scanning electron microscopy. Based on the results, gold grains were mostly liberated after bio-oxidation of sulfides, and in following CFSM treatment, large particles of carbonaceous aluminosilicate were formed from the aggregation of clay minerals, gold grains and with partially decomposed carbonaceous matters acting as binders..
56. Kojo T. Konadu, Susan Harrison, Kwadwo Osseo-Asare, Keiko Sasaki, Transformation of the carbonaceous matter in double refractory gold ore by crude lignin peroxidase released from the white-rot fungus, International Biodeterioration & Biodegradation, in press, 2019.06.
57. Quanzhi Tian, Shingo Nakama, Keiko Sasaki, Immobilization of cesium in fly ash-silica fume based geopolymers with different Si/Al molar ratio, Science of the Total Environment, 687, 1127-1137, 687 (2019)1127-1137, 2019.06.
58. Binglin Guo, Shingo Nakama, Quanzhi Tian, Niko Dian Pahlevi, Zhaochu Hu, Keiko Sasaki, Suppression processes of anionic pollutants released from fly ash by various Ca additives, Journal of Hazardous Materials, 10.1016/j.jhazmat.2019.03.036, 474-483, 2019.06, Harmful trace elements, which are initially included in the coal fly ash, have the potential to be leached when coal fly ash comes in contact with water. This causes a risk of pollutant species being released, considering the long lifetime of building structures where coal fly ash was applied. Some Ca additives effectively function to suppress the release of anionic pollutants; however, the detailed suppression processes remains unclear. In this work, the influences of various Ca additives on the released anionic pollutants (B, F, S, As, and Cr) was systematically investigated. According to the comprehensive results of solution data with the solid characterization, the 60% hydroxylated calcined dolomite (HCD 60) was the best Ca additive for the suppression of different anionic pollutants since this Ca source not only simply provides an alkaline reagent but also supplies MgO and Mg(OH) 2 , which affect the phase transformation that accompanies with hydration. The phase transformation occurs from Ca(OH) 2 to ettringite via hydrocalumite, which is the most important suppression processes of released pollutants. The precipitation of Ca salts is another pathway to immobilize these pollutants. In this scheme, MgO and Mg(OH) 2 were proven to enhance the formation of ettringite and hydrocalumite, respectively..
59. Paulmanickam Koilraj, Rajathsing Kalusulingam, Keiko Sasaki, Arginine and lysine-functionalized layered double hydroxides as efficient sorbents for radioactive Co2+ removal by chelate-facilitated immobilization, Chemical Engineering Journal, in press, 2019.05.
60. Subbaiah Muthu Prabhu, Srinivasarao Kancharla, Chang Min Park and Keiko Sasaki, Synthesis of modulator-driven highly stable zirconium-fumarate frameworks and mechanistic investigations of their arsenite and arsenate adsorption from aqueous solutions, RSC CrystEngComm, 10.1039/c8ce01424h, 21, 2320-2332, 2019.05, Here, we synthesized a modulator (benzoic acid (BA))-driven zirconium-fumaric acid (Zr-fum) metal–organic framework (MOF) and investigated in detail the adsorption mechanism of arsenic oxyanions (AsO43−and AsO33−) and their stability before and after adsorption from water. Without the support of the modulator, BA, Zr-fum formed an amorphous MOF due to the occurrence of quick precipitation of both zirconiumand -fum. Various amounts of BA, 0–10 eq. to ZrCl4, were used to control the surface charge on the MOF nanoparticles, which directly corresponds to the colloid stability of the MOF and helps to obtain a defect free
Zr-fum MOF for high uptakes of AsO43− and AsO33− from water. With the concentration of 3 eq. BA, the adsorption capacities of both arsenic oxyanions on the Zr-fum MOF were found to be higher than those on other MOFs. The CHN analysis indicated that the excess of -fum present does not alter the adsorption densities of AsO43− and AsO33− on MOFs in addition to the negligible amount of BA except for the Zr-fum-10 eq. BA MOF where it is present in higher amounts, as confirmed by NMR studies. The physicochemical properties of the synthesized MOFs with/without the modulator support adsorbents before and after the adsorption of AsO43− and AsO33− were extensively characterized using several advanced instrumental techniques. The maximum uptake performance of AsO43− (1.159 mmol g−1) and AsO33− (1.121 mmol g−1) was obtained using the Langmuir adsorption isotherm. The adsorption of both AsO4 3− and AsO3 3− takes place by electrostatic interaction/complexation and ligand exchange with Zr-fum-5 eq. BA. In addition, the Zr-fum-5 eq. BA was recycled up to four times at a sustained efficiency after washing with 0.1 M NaOH. Owing to their high uptake capacities of AsO4 3− and AsO3 3−, the synthesized MOFs are expected to have potential applications as adsorbents for practical applications..
61. Quanzhi Tian, Keiko Sasaki, Application of fly ash-based materials for stabilization/solidification
of cesium and strontium, Environmental Science and Pollution Research, https://doi.org/10.1007/s11356-019-05612-1, doi.org/10.1007/s11356-019-05612-1, 2019.05.
62. Xinhong Qiu, Keiko Sasaki, Shuang Xu, Jiawen Zhao, Double-Edged Effect of Humic Acid on Multiple Sorption Modes of Calcined Layered Double Hydroxides
Inhibition and Promotion, Langmuir, 10.1021/acs.langmuir.8b04196, 35, 19, 6267-6278, 2019.05, Layered double hydroxides (LDHs) are a typical class of anionic clay minerals whose structural memory effect has been widely used in pollutant adsorption. However, the influencing mechanism of humic acid (HA) on the structural memory effect in adsorption is not clear. In this study, HA was extracted from black soil and sediments, and its effect on the structural memory effect of LDHs with different divalent metals was evaluated in adsorption. Borate complexed with HAs and HAs promoted the dissolution of magnesium-calcined LDHs (Mg-CLDH), which enhanced their adsorption rate by Mg-CLDH. However, the adsorbed HA caused a decline in the crystallinity of the regenerated Mg-LDH and an incomplete structural transformation, thereby resulting in decreased adsorption capacity. After the complexation of HAs with borate, the resulting compound was adsorbed on the surface of Zn-CLDH. The adsorption rate of borate was effectively improved in the initial stage, but at the same time slowed down the hydration and structural regeneration of Zn-CLDH. Meanwhile, the surface-adsorbed HAs also prevented borate from entering the newly formed layer inside the particles and led to a significant decrease in adsorption performance. When Ca-CLDH was used to adsorb borate, the process mainly occurred through the formation of ettringite. However, the presence of HAs enhanced the stability of the restructured LDHs and hindered the dissolution of Ca-CLDH and the reaction with B(OH) 4 - to form ettringite during the regeneration process, which severely inhibited the sorption of borate..
63. Subbaiah Muthu Prabhu, Shunsuke Imamura, Keiko Sasaki, Mono-, Di-, and Tricarboxylic Acid Facilitated Lanthanum-Based Organic Frameworks
Insights into the Structural Stability and Mechanistic Approach for Superior Adsorption of Arsenate from Water, ACS Sustainable Chemistry and Engineering, 10.1021/acssuschemeng.8b06489, 7, 7, 6917-6928, 2019.04, In this study, we tried to synthesize lanthanum organic frameworks (MOFs) with the linkers of benzoic acid (BA), 1,4-benzene dicarboxylic acid, and 1,3,5-benzenetricarboxylic acid (BTC), abbreviated as La-BA, La-BDC, and La-BTC, respectively. Interestingly, the BA linker approached La metal to form lanthanum methanoate (La(HCOO)
3
) instead of the La-BA MOF through an acid catalyst amide-hydrolysis mechanism, whereas La-BDC and La-BTC act as MOFs, confirmed by PXRD patterns. Various sophisticated instrumentation techniques such as FTIR, PXRD, XPS, BET, and TGA were utilized to understand the formation of MOF. This is the first report to investigate AsO
4

3-
adsorption and the dissolution behavior of La-BA, La-BDC, and La-BTC in detail using different spectroscopic methods. The maximum AsO
4

3-
adsorption densities obtained from the Langmuir isotherm model were found to be 2.623, 3.891, and 0.280 mmol/g for La-BA, La-BDC, and La-BTC, respectively, where the dose ratio was 1 g/L with the speed of 100 rpm at room temperature. The value for La-BDC was significantly superior to the previously reported adsorbents for AsO
4

3-
to date. The presence of AsO
4

3-
on both La-BA and La-BDC was confirmed by FTIR and XPS As 3d. After adsorption of 2.4 mM AsO
4

3-
, the precipitation mechanism controls the adsorption capacities on La-BA and the ligand exchange mechanism on La-BDC confirmed by solution as well as solid analyses. Sorption kinetic data of AsO
4

3-
followed a pseudo-second-order model, which is consistent with chemisorption involving the possible coordination of AsO
4

3-
on La-BA and La-BDC. These results suggested that the MOF materials can be developed to immobilize arsenic-rich wastewater..
64. Kojo T. Konadu, Robert J. Huddy, Susan T. L. Harrison, Kwadwo Osseo-Asare, Keiko Sasaki, Bio-mineral processing of double refractory gold ore in sequential treatment using a thermophilic archaeon followed by fungal spent medium, Minerals Engineering, 138, 86-94, 2019.03.
65. Quanzhi Tian, Keiko Sasaki, Characterizations of Calcium Silicate Hydrates deprived from Coal Fly Ash and Their Mechanisms for Phosphate Removal, Desalination and Water Treatment, in press, 2019.03.
66. Chitiphon Chuaicham, Radheshyam Pawar, Keiko Sasaki, Dye-sensitized photocatalyst of sepiolite for organic dye degradation, Catalysts, 10.3390/catal9030235, 9, 3, 2019.03, The photocatalytic activity of sepiolite was examined for degradation of several dye compounds under visible light irradiation. Higher adsorption capacities and greater photocatalytic performance of cationic dyes (rhodamine B and methylene blue) were observed on sepiolite, in comparison with anionic dyes (orange II and trypan blue). Superiority in the photocatalytic activity of cationic dyes is attributed to the strong electrostatic attraction and photosensitization properties of cationic dye molecules. Sepiolite has degraded 45.3% rhodamine B within 120 min, which is the greatest photocatalytic degradation efficiency when compared with other dyes. Subsequently, the reusability of spent sepiolite after adsorption of rhodamine B was evaluated by the degradation of trypan blue under the visible light irradiation. The photocatalytic degradation performance of trypan blue by spent sepiolite after adsorption of rhodamine B increased about twice as much as with pristine sepiolite, indicating that the dye-sensitized photocatalytic process could enhance the photocatalytic degradation ability of sepiolite. Through radical scavenger tests, it was found that a superoxide radical is mainly responsible for rhodamine B degradation. The possible mechanism of rhodamine B degradation under visible light irradiation was proposed. The sepiolite could be a potential catalyst for the degradation of organic pollutants in wastewater under solar light. View Full-Text.
67. Quanzhi Tian, Binglin Guo, Shingo Nakama, Li Zhang, Zhaochu Hu, Keiko Sasaki, Reduction of Undesirable Element Leaching from Fly Ash by adding Hydroxylated Calcined Dolomite, Waste Management, 10.1016/j.wasman.2019.01.027, in press, 2019.01.
68. Wuhui Luo, Qidong Huang, Binglin Guo, Keiko Sasaki, Organo-montmorillonite encapsulated in alginate for simultaneous adsorption of ClO4- and Sr2+ from aqueous solutions: Mechanism of synergistic effects and implication for radionuclide immobilization, Journal of Colloid and Interface Science, 2019.01.
69. Srinivasarao Kancharla, Keiko Sasaki, Acid tolerant covalently functionalized graphene oxide for the selective extraction of Pd from high-level radioactive liquid wastes, Journal of Materials Chemistry A, 10.1039/c8ta09849b, 7, 9, 4561-4573, 2019.01, The severely depleting reserves of highly demanded palladium (Pd) induce the growing pressure on its recycling. One of the potential secondary sources of Pd is a high-level liquid waste (HLLW) produced from spent nuclear fuel. HLLW contains several metal ions along with Pd in 3-4 M HNO
3
medium. The preparation of highly acid tolerant and efficient functional materials is a challenging task in the solid phase recovery of noble metals. We have explored covalently functionalized graphene oxide (GO) to overcome this issue. GO was covalently functionalized with 1-(3-aminopropyl)imidazole (ImGO) (N-donor) and 2-methylthiophene (ThpGO) (S-donor) through amide or amine formation at different reactive sites. The prepared materials before and after Pd recovery were thoroughly characterized using a variety of state-of-the-art techniques. Solid-phase extraction experiments revealed that the Pd was recovered with remarkable selectivity from HLLW-like solutions in 3 M HNO
3
using both the functionalized materials. The extraction efficiency was found to be higher than that of any of the solid-state materials reported to date. The sorption of Pd onto ImGO and ThpGO was best expressed by the Freundlich isotherm model. The advantages of the prepared materials are twofold: the first one is the high tolerance to harsh acidic conditions, and the second one is the higher selectivity and efficiency for Pd. The sorption of Pd onto ImGO was achieved by complete anion exchange with the nitrate ion, whereas ThpGO recovered Pd through a co-ordination mechanism. The results demonstrated that the developed covalently functionalized GO was the first choice material for the efficient and selective recovery of Pd..
70. Quanzhi Tian, Keiko Sasaki, Application of fly ash-based geopolymer for removal of cesium, strontium and arsenate from aqueous solutions
Kinetic, equilibrium and mechanism analysis, Water Science and Technology, 10.2166/wst.2019.209, 79, 11, 2116-2125, 2019.01, Geopolymerization is a developing reaction process for the utilization of solid wastes. In the present study, fly ash-based geopolymer and its derivative (Fe(II)-modified geopolymer) were synthesized and characterized using XRD, SEM, FTIR, BET, UV-Vis DRS as well as TG-DTA, and adopted as adsorbents for removal of Csþ and Sr, and AsO3 4 from solutions. Each sorption kinetic was well fitted to the pseudo-second-order model. The sorption of Csþ and Sr onto original geopolymer were better fitted to the Langmuir model. However, the Freundlich model is more befitting for sorption of AsO3 4 onto Fe(II)-modified geopolymer. The free energies calculated from the D-R isotherm indicated that the sorption for Csþ and Sr were dominantly ion exchanges. Ring size plays a decisive role in ion exchanges for both Csþ and Sr. Furthermore, the arrangement of SiO4 and AlO4 tetrahedrons has significant impacts on the ion exchange of Sr. XPS results indicated that a part of Fe in Fe (II)-modified geopolymer had been oxidized to Fe after sorption. Precipitation of FeAsO4 could partially contribute to the arsenate removal from solution. AsO3 4 sorption has also occurred through the formation of inner-sphere complexes via ion exchange reaction, which could be predominantly attached by bidentate linkages..
71. Santisak Kitjanukit, Keiko Sasaki, Naoko Okibe, Production of highly catalytic, archaeal Pd(0) bionanoparticles using Sulfolobus tokodaii, Extremophiles, 10.1007/s00792-019-01106-7, 2019.01, The thermo-acidophilic archaeon, Sulfolobus tokodaii, was utilized for the production of Pd(0) bionanoparticles from acidic Pd(II) solution. Use of active cells was essential to form well-dispersed Pd(0) nanoparticles located on the cell surface. The particle size could be manipulated by modifying the concentration of formate (as electron donor; e-donor) and by addition of enzymatic inhibitor (Cu2+) in the range of 14–63 nm mean size. Since robust Pd(II) reduction progressed in pre-grown S. tokodaii cells even in the presence of up to 500 mM Cl, it was possible to conversely utilize the effect of Cl to produce even finer and denser particles in the range of 8.7–15 nm mean size. This effect likely resulted from the increasing stability of anionic Pd(II)–chloride complex at elevated Cl concentrations, eventually allowing involvement of greater number of initial Pd(0) crystal nucleation sites (enzymatic sites). The catalytic activity [evaluated based on Cr(VI) reduction reaction] of Pd(0) bionanoparticles of varying particle size formed under different conditions were compared. The finest Pd(0) bionanoparticles obtained at 50 mM Cl (mean 8.7 nm; median 5.6 nm) exhibited the greatest specific Cr(VI) reduction rate, with four times higher catalytic activity compared to commercial Pd/C. The potential applicability of S. tokodaii cells in the recovery of highly catalytic Pd(0) nanoparticles from actual acidic chloride leachate was, thus, suggested..
72. Subbaiah Muthu Prabhu, Srinivasarao Kancharla, Chang Min Park, Keiko Sasaki, Synthesis of modulator-driven highly stable zirconium-fumarate frameworks and mechanistic investigations of their arsenite and arsenate adsorption from aqueous solutions, CrystEngComm, 10.1039/C8CE01424H, 21, 14, 2320-2332, 2019.01, Here, we synthesized a modulator (benzoic acid (BA))-driven zirconium-fumaric acid (Zr-fum) metal-organic framework (MOF) and investigated in detail the adsorption mechanism of arsenic oxyanions (AsO43− and AsO33−) and their stability before and after adsorption from water. Without the support of the modulator, BA, Zr-fum formed an amorphous MOF due to the occurrence of quick precipitation of both zirconium and -fum. Various amounts of BA, 0-10 eq. to ZrCl4, were used to control the surface charge on the MOF nanoparticles, which directly corresponds to the colloid stability of the MOF and helps to obtain a defect-free Zr-fum MOF for high uptakes of AsO43− and AsO33− from water. With the concentration of 3 eq. BA, the adsorption capacities of both arsenic oxyanions on the Zr-fum MOF were found to be higher than those on other MOFs. The CHN analysis indicated that the excess of -fum present does not alter the adsorption densities of AsO43− and AsO33− on MOFs in addition to the negligible amount of BA except for the Zr-fum-10 eq. BA MOF where it is present in higher amounts, as confirmed by NMR studies. The physicochemical properties of the synthesized MOFs with/without the modulator support adsorbents before and after the adsorption of AsO43− and AsO33− were extensively characterized using several advanced instrumental techniques. The maximum uptake performance of AsO43− (1.159 mmol g−1) and AsO33− (1.121 mmol g−1) was obtained using the Langmuir adsorption isotherm. The adsorption of both AsO43− and AsO33− takes place by electrostatic interaction/complexation and ligand exchange with Zr-fum-5 eq. BA. In addition, the Zr-fum-5 eq. BA was recycled up to four times at a sustained efficiency after washing with 0.1 M NaOH. Owing to their high uptake capacities of AsO43− and AsO33−, the synthesized MOFs are expected to have potential applications as adsorbents for practical applications..
73. Quanzhi Tian, Keiko Sasaki, Structural characterizations of fly ash-based geopolymer after adsorption of various metal ions, Environmental Technology (United Kingdom), 10.1080/09593330.2019.1649469, 2019.01, Geopolymer, an amorphous substance, has been viewed as good adsorbent or catalyst and attracted much attentions from all over the world. In order to achieve the better applications of geopolymer in these fields, a deep understanding of the microstructure of geopolymer would be strongly required. In the present study, geopolymer was synthesized from coal fly ash, and the structural analysis of geopolymer after adsorption of various metal ions (Li+, Cs+, Sr2+ and Co2+) was studied using XRD, SEM-EDX, FTIR, UV-VIS DRS, TG-DTA as well as surface area and pore distribution analysis. Pair distribution function preferably illustrated that geopolymer was successfully prepared from calcined fly ash. Geopolymer possesses different affinities towards various metal ions. After exchanging with other metal ions, the main structure of geopolymer was maintained. Metal ions with a large radius would have greater effect on the existing state and amount of water molecules in geopolymer. Moreover, the specific surface area of geopolymer after exchanging with metal ions decreased as a function of the radius of them. The spectra corresponding to d-d transitions indicated that the Co2+ could be incorporated into the deformed six-member rings or eight-membered rings. It could be deduced that the sites for ion exchange could be different rings or even cavities distributed on the surface layer of geopolymer. Furthermore, the rings distributed in the geopolymer structure were predominant in the 6-, 8-, 10- or even 12-member rings to maintain the structure stability and charge balance with the cations..
74. Shuang Xu, Jiawen Zhao, Qianqian Yu, Xinhong Qiu, Keiko Sasaki, Understanding how specific functional groups in humic acid affect the sorption mechanisms of different calcinated layered double hydroxides, Chemical Engineering Journal, 10.1016/j.cej.2019.123633, 392, 2019.01, Humic acid (HA) can affect the adsorption modes of CLDHs, and change the form of pollutants, making it a key factor when considering CLDHs for practical applications. However, the complicated and uncertain structures of HA make it difficult to explore how they will influence the mechanism, so using simple compounds to simulate the role of different reactive groups in HA necessary to understand how they will interact with the application of CLDHs. It was found that both CLDHs strongly adsorb phthalic acid and catechol. All hydroxyl and carboxyl compounds had a similar promoting effect on the adsorption rate and regeneration rate of Mg-CLDH, which were not affected by the number of functional groups, the length of the aliphatic chain, or the number of the aromatic ring. However, their effects were more significant than that of the HA. While they could make the structure of Mg-LDH stacked and incomplete, just like the HA, they did not damage the crystallinity. In particular, catechol inhibited the regeneration of Mg-CLDH to a certain degree. Since the regeneration process was different from Mg-CLDH, different types of hydroxyl or carboxyl compounds degraded the removal of borate by Ca-CLDH, but promoted the formation of ettringite to some extent, especially benzoic acid and 4-phenylbutyric acid. However, catechol severely inhibited the structural transformation of Ca-CLDH into ettringite. Due to the strong interaction of the HA with the surface of Ca-LDH, the formation of ettringite was hindered, which deteriorated the removal of borate. HA did change the adsorption rate and the regeneration process of CLDHs via different reactive groups, and their effects on various CLDHs were different..
75. Kancharla Srinivasarao, Keiko Sasaki, Acid tolerant covalently functionalized graphene oxide for the selective extraction of Pd from high-level radioactive liquid wastes, Journal of Material Chemistry A, in press, 2018.12, The severely depleting reserves of highly demanded palladium (Pd) induce the growing pressure on its recycling. One of the potential secondary sources of Pd is a high-level liquid waste (HLLW) produced
from spent nuclear fuel. HLLW contains several metal ions along with Pd in 3–4 M HNO3 medium. The preparation of highly acid tolerant and efficient functional materials is a challenging task in the solid
phase recovery of noble metals. We have explored covalently functionalized graphene oxide (GO) to overcome this issue. GO was covalently functionalized with 1-(3-aminopropyl)imidazole (ImGO) (Ndonor)
and 2-methylthiophene (ThpGO) (S-donor) through amide or amine formation at different reactive sites. The prepared materials before and after Pd recovery were thoroughly characterized using a variety of state-of-the-art techniques. Solid-phase extraction experiments revealed that the Pd was recovered with remarkable selectivity from HLLW-like solutions in 3 M HNO3 using both the functionalized materials. The extraction efficiency was found to be higher than that of any of the solidstate materials reported to date. The sorption of Pd onto ImGO and ThpGO was best expressed by the Freundlich isotherm model. The advantages of the prepared materials are twofold: the first one is the
high tolerance to harsh acidic conditions, and the second one is the higher selectivity and efficiency for Pd. The sorption of Pd onto ImGO was achieved by complete anion exchange with the nitrate ion,
whereas ThpGO recovered Pd through a co-ordination mechanism. The results demonstrated that the developed covalently functionalized GO was the first choice material for the efficient and selective recovery of Pd..
76. Chitiphon Chuaicham, Radhesham Pawar, Keiko Sasaki, Dye-sensitized Photocatalyst of Sepiolite for Organic Dye Degradation, Catalysts, 9(2019) 235-251, 2018.12.
77. Subbaiah Muthu Prabhu, Shunsuke Imamura, Keiko Sasaki*, Mono-, di- and tri-carboxylic acid facilitated lanthanum-based organic frameworks: Insights into the structural stability and mechanistic approach for superior adsorption of arsenate from water, ACS Sustainable Chemistry and Engineering, in press, 2018.12, In this study, we synthesized three metal organic frameworks (MOFs) of La, with benzoic acid (BA), 1,4-benzene dicarboxylic acid (BDC) and 1,3,5-benzenetricarboxylic acid (BTC), abbreviated as La-BA, La-BDC and La-BTC, respectively. Interestingly, the BA ligand approached La metal to form lanthanum methanoate (La(HCOO)3 instead of the La-BA MOF through an acid catalyst amide-hydrolysis mechanism, whereas La-BDC and La-BTC act as MOFs, confirmed by PXRD patterns. The mechanism of MOF formation was revealed through PXRD, FT-IR, XPS and ICP-OES analyses. This is the first report to investigate AsO43- adsorption and the dissolution behavior of La-BA, La-BDC and La-BTC in detail using different spectroscopic methods. The maximum adsorption capacities of AsO43- obtained from the Langmuir isotherm model were found to be 2.623, 3.891 and 0.280 mmol/g for La-BA, La-BDC and La-BTC, respectively, where the the dose ratio of 1 g/L with the speed of 100 rpm at room temperature. The value for La-BDC was significantly superior to the previously reported adsorbents for AsO43- to date. The presence of AsO43- on both La-BA and La-BDC was confirmed by FTIR and XPS As 3d. The PXRD patterns confirmed the formation of LaAsO4 by the precipitation mechanism after adsorption of 2.4 mM AsO43- on both La-BA and La-BDC. Sorption kinetic data of AsO43- followed a pseudo-second-order model, which is consistent with chemisorption involving the possible coordination of AsO43- on La-BA and La-BDC. These results suggested that the MOF materials can be developed for the immobilization of AsO43- from waste water..
78. Santisak Kitjanukit; Keiko Sasaki; Naoko Okibe, Production of highly-catalytic, archaeal Pd(0) bionanoparticles using Sulfolobus tokodaii, Extremophile, in press., 2018.12.
79. Paulmanickam Koilraj, Yuta Kamura, Keiko Sasaki, Cosorption Characteristics of SeO4 2- and Sr2+ Radioactive Surrogates Using 2D/2D Graphene Oxide-Layered Double Hydroxide Nanocomposites, ACS Sustainable Chemistry and Engineering, 10.1021/acssuschemeng.8b02056, 6, 11, 13854-13866, 2018.11, Cosorption of anionic and cationic radioactive nuclides is highly desired toward the total cleaning of radioactive contaminated wastewater. A 2D/2D multifunctional nanocomposite of MgAl-LDH/graphene oxide (GO) was fabricated using coagulation and applied for the cosorption of Sr2+ and SeO4 2- from aqueous solution. The cosorption was synergetically enhanced with the copresence of each species and showed a maximum Sr2+ removal of 2.435 mmol/g of GO. The synergetic effect occurs only in the MgAl-LDH/GO nanocomposite because of the synchronized effect of MgAl-LDH, GO, and alkaline cations, which were not present in pure GO. The SeO4 2- removal occurred by the interchange of the NO3 - anion from the LDH, while the removal of Sr2+ occurred through coordination with carboxyl/alkoxy (âCOO-/-CO-) groups in GO by the ring opening of epoxides. The cosorption efficiencies of Sr2+ and SeO4 2- were stable in the wide pH range of 4-10. The binary (Na2SeO4 + SrCl2) and ternary (Na2SeO4 + SrCl2 + M+/M2+ = other metal ions or An- = other negative ions) systems enhanced the cosorption of Sr2+ and SeO4 2- in the presence of other alkali and alkali earth metals and other anions compared with the single system. The Sr2+ and SeO4 2- sorption densities were superior to previously reported values. The combined multifunctional ability and environmentally benign nature of the MgAl-LDH/GO composite is promising as a sustainable material for the total remediation of Sr2+ and SeO4 2- radioactive surrogates and can also be extended to wide combinations of divalent anions and cations..
80. Quanzhi Tian, Binglin Guo, Shingo Nakama, Keiko Sasaki, Distributions and Leaching Behaviors of Toxic Elements in Fly Ash, ACS Omega, 10.1021/acsomega.8b02096, 3, 10, 13055-13064, 2018.10, Fly ash usually contains a considerable amount of toxic elements that can be leached into the environment, thereby easily leading to serious contaminations. In this work, the leaching behaviors of poisonous elements including boron (B), phosphorus (P), vanadium (V), chromium (Cr), arsenic (As), selenium (Se), molybdenum (Mo), antimony (Sb), and tungsten (W) from fly ash were explored by sequential extraction. Importantly, the associations of these elements in fly ash were discussed based on their leaching and X-ray absorption near-edge structure (XANES) results. From the XANES results, it was observed that V(IV), Cr(III), As(V), Se(IV), and W(IV) were their main states of existence in fly ash. In terms of leaching results, large amounts of Mo and W were leached into pure water, which indicated their high mobilities. Furthermore, the occurrence of Mo in fly ash was mainly in the form of oxides, and W had complex associations including WX
4
(X can be monovalent anions), its reduction state or association with the elements that can be oxidized, and existence in silicates. B was as easily released into the environment as Mo and W. It can have several associations with the other cations, such as Ca
2+
, Na
+
, and Mg
2+
, and occurs in silicates. In contrast, most of the Cr and Sb were locked in silicates, indicating that they were very stable in fly ash. In addition, P, V, and As can exist within the structure of silicates as well. However, a considerable amount of them leached in the reduction step with a low pH. Hence, they can be associated with Ca
2+
, Na
+
, Mg
2+
, or Fe
3+
. In terms of Se, oxidation processes played an important role in controlling its leaching because of the oxidation of Se(IV) to Se(VI). Calcium selenite should be the predominant form of Se in fly ash..
81. Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, Hajime Miki, Keiko Sasaki, Masashi Yamane, Eri Takida, Shigeto Kuroiwa, Yuji Imaizumi, Effect of Fenton-like oxidation reagent on hydrophobicity and floatability of chalcopyrite and molybdenite, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 10.1016/j.colsurfa.2018.06.029, 554, 34-48, 2018.10, A fundamental study is provided in this work to understand the effect of Fenton-like reagent made by the addition of FeSO4 in H2O2 aqueous solution on surface hydrophobicity and floatability of chalcopyrite (CuFeS2) and molybdenite (MoS2). Contact angle measurements were performed to assess the surface hydrophobicity. The contact angle results showed that Fenton-like reagent could alter the surface hydrophobicity of chalcopyrite at lower concentration of H2O2 aqueous solution compared to that of using H2O2 aqueous solution. On the other hand, molybdenite surface remained hydrophobic after the oxidation treatments using Fenton-like reagent and H2O2 aqueous solution. Surface characterizations using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) shows that the chalcopyrite surface covered with a thicker layer of oxidation products after the oxidation treatment using Fenton-like reagent, indicating a stronger surface oxidation. Flotation results were in agreement with contact angle results, showing that Fenton-like reagent could depress the floatability of chalcopyrite at lower concentration of H2O2 aqueous solution. On the other hand, molybdenite recovery remained high under various oxidation treatments owing to low surface oxidation..
82. Kancharla Srinivasarao, Subbaiah Muthu Prabhu, Wuhui Luo, Keiko Sasaki, Enhanced adsorption of perchlorate by gemini surfactant-modified montmorillonite
Synthesis, characterization and their adsorption mechanism, Applied Clay Science, 10.1016/j.clay.2018.07.010, 163, 46-55, 2018.10, Organo-montmorillonites (OMt) adsorb perchlorate (ClO4 ) through anion exchange mechanism. Each gemini surfactant (GCn) provides two anion exchangeable sites due to its unique molecular structure. Due to the presence of more anion exchangeable sites, the preparation of OMt with GCn enables the possibility for higher amount of ClO4 uptake than their single-chain counterparts. In this work, gemini surfactant modified montmorillonites (GCn-Mt) were synthesized using three different alkyl chain length containing gemini surfactants (CnH2n+1(Me)2-C6H12-CnH2n+1(Me)2·2Cl), where n varied to 12, 14 and 16 and were examined in detail for the adsorption of ClO4 from aqueous solution. The structure of the GCn-Mt before and after adsorption of ClO4 was characterized by an array of techniques such as powder XRD, FT-IR, XPS, TGA and CHN analysis. The adsorption of ClO4 onto the GCn-Mt was best described by the Langmuir adsorption isotherm and pseudo-second-order kinetic model. The GC16-Mt showed the highest removal capacity of 1.08 mmol/g and at a rapid rate, achieving 95% within 1 min, with an equilibrium time of 15 mins. The GC16-Mt retained its high removal capacity and selectivity in presence of a variety of coexisting anions such as HCO3 , NO3 , CO3 2−, SO4 2−, SiO3 2−, and H2PO4 , and at a wide pH range (2−12). Combining the high removal capacity and selectivity with fast kinetics, the GCn-Mt has great potential for ClO4 removal from aqueous solutions..
83. Paulmanickam Koilraj, Yuta Kamura, Keiko Sasaki, Co-immobilization characteristics of SeO42- and Sr2+ radioactive surrogates using 2D/2D graphene oxide-layered double hydroxide nanocomposites, ACS Sustainable Chemistry in Engineering, 2018.09.
84. Subbaiah Muthu Prabhu, Kancharla Srinivasarao, Keiko Sasaki, Synthesis of modulator-driven highly stable zirconium-fumarate frameworks and their mechanistic investigations for the adsorption of arsenite and arsenate from aqueous solutions, RSC Cryst Eng Comm, in press, 2018.09.
85. Quanzhi Tian, Binglin Guo, Shingo Nakama, Keiko Sasaki, Distributions and Leaching Behaviors of Toxic Elements in Fly Ash, ACS Omega, 2018.09.
86. Binglin Guo, Shingo Nakama, Quanzhi Tian, Niko Dian Pahlevi, Li Zhang, Zhaochu Hu, Keiko Sasaki, Suppression mechanisms of anionic pollutants released from fly ash by different Ca additives, J. Hazard. Mater., 371(2019)474-483, 2018.09.
87. Masahito Tanaka, Keiko Sasaki, Naoko Okibe, Behavior of sulfate ions during biogenic scorodite crystallization from dilute As(III)-bearing acidic waters, Hydrometallurgy, 10.1016/j.hydromet.2018.07.018, 180, 144-152, 2018.09, This study revealed the importance of SO4
2− ions during biogenic scorodite crystallization via a two-stage As-removal process, using a combination of liquid and solid analyses (chemical digestion, FT-IR, SEM, TG-DTA, particle distribution). The first-stage As-removal was induced by microbial oxidation of Fe2+ and As(III), precipitating SO4
2−-bearing amorphous precursors composed of basic ferric sulfate (MFex(SO4)y(OH)z) and ferric arsenate (FeAsO4·(2 + n)H2O). This was followed by an induction period (a period of constant concentration), where dissolution-recrystallization of unstable amorphous precursors proceeded: Re-dissolved metal ions became locally concentrated on the surface of precursors, which gave the driving force for the second-stage As-removal as secondary layers of crystalline biogenic scorodite (Fe(AsO4)0.94(SO4)0.08·1.69H2O) out of even more dilute and seeded solution. This phase transformation process was also accompanied by continuous dehydration. This two-stage As-removal via SO4
2−-mediated phase transformation was shown to be key to promote biogenic scorodite formation with greater final As-removal from dilute As(III)-bearing solutions..
88. Keiko Sasaki, Yoshikazu Hayashi, Kenta Toshiyuki, Binglin Guo, Simultaneous immobilization of borate, arsenate, and silicate from geothermal water derived from mining activity by co-precipitation with hydroxyapatite, Chemosphere, 10.1016/j.chemosphere.2018.05.074, 207, 139-146, 2018.09, The treatment of the geothermal water discharged through mining activity is a critical issue because the rate of discharge is 12,000 m3 per day and the discharge contains high concentrations of borate (>20 mg/L) and arsenate (ca. 0.4 mg/L) as well as silicate and carbonate. The simultaneous reduction of borate and arsenate concentrations to acceptable levels was successfully performed by co-precipitation with hydroxyapatite (HAp). Although the coexisting high concentrations of carbonate act as a disturbing element, the co-precipitation equilibrium of borate was shifted to lower values by adjusting the P/Ca molar ratio, and the removal rate of borate was accelerated by using Al3+ additives, resulting in the efficient reduction of borate within 1 h. The initially immobilized boron in HAp is in the tetragonal form, which probably occupies the hydroxyl sites in HAp, gradually transforming into the trigonal form in the solid state, as interpreted by 1H NMR and 11B-NMR. The coexisting silicate was also immobilized in an ellestadite form, as confirmed by 29Si-NMR measurements. Arsenate and silicate were immobilized before borate in geothermal water. A dissolution assay of borate in the solid residues after co-precipitation with HAp verified the acceptable stability of borate, which is independent of the amount of added Al3+..
89. Kancharla Srinivasarao, Subbaiah Muthu Prabhu, Wuhui Luo, Keiko Sasaki, Enhanced adsorption of perchlorate by gemini surfactant-modified montmorillonite: Synthesis, characterization and their adsorption mechanism, Applied Clay Science, org/10.1016/j.clay.2018.07.010, 163, 46-55, 2018.07.
90. Keiko Sasaki, Yoshikazu Hayashi, Kenta Toshiyuki, Binglin Guo, Simultaneous immobilization of borate, arsenate, and silicate from geothermal water derived from mining activity by co-precipitation with hydroxyapatite, Chemosphere, 207, 139-146, 2018.06, The treatment of the geothermal water discharged through mining activity is a critical issue because the rate of discharge is 12,000m3 per day and the discharge contains high concentrations of borate (>20 mg/ L) and arsenate (ca. 0.4 mg/L) as well as silicate and carbonate. The simultaneous reduction of borate and arsenate concentrations to acceptable levels was successfully performed by co-precipitation with hydroxyapatite element, the co-precipitation equilibrium of borate was shifted to lower values by adjusting the P/Ca molar ratio, and the removal rate of borate was accelerated by using Al3þ additives, resulting in the efficient reduction of borate within 1 h. The initially immobilized boron in HAp is in the tetragonal form, which probably occupies the hydroxyl sites in HAp, gradually transforming into the trigonal form in the solid state, as interpreted by 1H NMR and 11B-NMR. The coexisting silicate was also immobilized in an
ellestadite form, as confirmed by 29Si-NMR measurements. Arsenate and silicate were immobilized before borate in geothermal water. A dissolution assay of borate in the solid residues after coprecipitation with HAp verified the acceptable stability of borate, which is independent of the amount of added Al3+..
91. Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, Hajime Miki, Keiko Sasaki, Effect of Fenton-like oxidation reagent on hydrophobicity and floatability of chalcopyrite and molybdenite, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 554, 34-48, 2018.06.
92. Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, Hajime Miki, Keiko Sasaki, Masashi Yamane, Eri Takida, Shigeto Kuroiwa, Yuji Imaizumi, Selective flotation of chalcopyrite and molybdenite using H2O2 oxidation method with the addition of ferrous sulfate, Minerals Engineering, 10.1016/j.mineng.2018.02.005, 122, 312-326, 2018.06, Hydrogen peroxide (H2O2) has been used as an oxidizing agent in the selective flotation of chalcopyrite and molybdenite. However, this method required relatively high concentration of H2O2 to deliver flotation results (i.e., mineral grades and recoveries) comparable to those obtained by the conventional copper-molybdenum (Cu-Mo) ores flotation using sodium hydrosulfide (NaHS). Therefore, further improvements are needed to reduce the consumption of H2O2 reagent. In this study, ferrous sulfate (FeSO4) was used to enhance the oxidation performance of H2O2 through Fenton-like reactions. Flotation results showed that the consumption of H2O2 reagent could be reduced by the addition of FeSO4 without losing the flotation selectivity. The reason might be caused by increasing of oxidation performance as indicated by the increasing concentration of dissolved oxygen after the addition of FeSO4 into the H2O2 aqueous solution. Surface analysis using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) images showed that the surface of chalcopyrite was covered by more hydrophilic precipitates after the oxidation treatment using H2O2 aqueous solution with the addition of FeSO4, thus more hydrophilic surface and lower floatability. On the other hand, the surface of molybdenite was slightly oxidized and its surface remained hydrophobic as confirmed from contact angle results. Flotation tests using Cu-Mo bulk concentrate demonstrated that selective flotation might be possible using a mixture of FeSO4 and H2O2 aqueous solution. Moreover, this new method could be used as an alternative to copper depressant in Cu-Mo selective flotation, replacing the NaHS reagent..
93. Paulmanickam Koilraj, Yuta Kamura, Keiko Sasaki, Synergetic co-immobilization of SeO42- and Sr2+ from aqueous solution onto graphene oxide and carbon-dot based layered double hydroxide nanocomposites and their mechanistic investigation, RSC J. Material Chemistry A, 10.1039/C8TA01605D, 6, 10008-10018, 2018.05, The co-immobilization of radioactive Sr2+ and SeO42- using a multifunctional material is an interesting area of research for the total remediation of radioactive wastes. However, it is rather challenging to target both the anion and cation through the realization of a multifunctional ability of the resultant sorbent. In this work, MgAl–NO3-layered double hydroxides (LDHs) containing graphene oxide (GO) and carbon dot (C-dot) nanocomposites were synthesized and contrasted for the co-immobilization of Sr2+ and SeO42-. Zeta potential measurements and TEM observation of the MgAl–NO3-LDH/C-dot composite indicated that the carbon-nanodot was attached to the surface of LDH nanosheets, while in the MgAl–NO3-LDH/GO composites the LDH nanosheets were decorated on the larger sized GO nanosheets. Adsorption studies found that the normalized Sr2+ adsorption capacity was 1.793 mmol g-1 on MgAl–NO3-LDH/GO, which was nine times higher than that for the MgAl–NO3-LDH/C-dot composite and GO. The enhancement in the Sr2+ adsorption capacity is due to the co-operative effect of the LDH and GO. The adsorption of Sr2+ on the MgAl–NO3-LDH/C-dot occurs by coordination with the –COO group, while ligand exchange and ionic interaction with the alkoxide anion are the dominant mechanisms on the MgAl–NO3-LDH/GO composite. Moreover, the adsorption capacity of both Sr2+ and SeO42- increased synergistically in the bi-component system containing both ions. The present technique is promising and offers a sustainable and environmentally friendly multifunctional material for the co-immobilization of both anionic and cationic radioactive surrogates from aqueous solutions..
94. Hajime Miki, Tsuyoshi Hirajima, Yukihiro Muta, Gde Pandhe Wisnu Suyantara, Keiko Sasaki, Effect of sodium sulfite on floatability of chalcopyrite and molybdenite, Minerals, 10.3390/min8040172, 2018.05.
95. Zhisheng Gao, Keiko Sasaki, Xinhong Qiu, Structural memory effect of Mg-Al and Zn-Al layered doubled hydroxides in the presence of natural humic acid, Langmuir, 10.1021/acs.langmuir.8b00059, 34, 5386-5395, 2018.05, The structural memory effect of layered double hydroxides (LDHs) is one of the important reasons for their extensive use in environmental remediation. In this study, humic acid (HA) was extracted from black soil and sediments and characterized to determine their structures. The regeneration mechanisms of calcinated LDHs (CLDHs) including different divalent metals (Mg-CLDH and Zn-CLDH) in deionized water and different HA solutions were carefully elucidated, and the reasons for the behavior differences in the two materials were explained. The presence of the HAs significantly increased the dissolution rate of Mg2+ ions from Mg-CLDHs and subsequent regeneration of Mg-LDH. Because of the diverse functional groups in the HAs, these groupswere complexed with metallic ions such as Mg2+ on the surface of Mg- CLDH in the beginning. During the process, the HAs adsorbed the regenerated LDHs on the surfaces. Therefore, the crystallinity, morphology, and specific surface area of the regenerated Mg-LDH significantly changed, especially in the presence of high concentrations of HA. In the case of Zn-CLDH, the regeneration rate of the LDH increased in the presence of HA, but the surface of Zn-CLDH was covered with regenerated Zn-LDH and HA. Then, the inside of the particles could not transform to LDH, leading to poor crystallinity and a significant increase in the ZnO content of the HA system..
96. Subbaiah Muthu Prabhu, Chitiphon Chuaicham, Keiko Sasaki, A Mechanistic Approach for the Synthesis of Carboxylate-Rich Carbonaceous Biomass-Doped Lanthanum-Oxalate Nanocomplex for Arsenate Adsorption, ACS Sustainable Chemistry and Engineering, 10.1021/acssuschemeng.7b04678, 6, 5, 6052-6063, 2018.05, Considering the protocol of "zero-alkaline waste disposal" for green and arsenic-free environment, lanthanum (La3+)-based MOF-like complex materials were designed, and the complex materials have been employed as adsorbent for AsO4
3- adsorption from water. The sucrose-derived porous carbon (SPC)@La-oxalate complex was prepared by a simple one-pot coprecipitation method at room temperature, where oxalate has been used as an organic ligand, and the carbonaceous biomass has been used as a doping material that is naturally a carboxylate-rich functional group derived from a sucrose biomass. In addition to SPC@La-oxalate, bare-SPC, La(OH)3, and SPC@La(OH)3 were also prepared via simple base-addition conventional methods, and their performances in AsO4
3- removal were compared. The FTIR peak at 848 cm-1 confirmed the presence of AsO4
3- on the SPC@La-oxalate complex after adsorption of 1 mM AsO4
3-. The high resolution X-ray photoelectron spectrum for the AsO4
3- adsorbed SPC@La-oxalate showed a peak at EB[As 3d] = 45.2 eV, which could be attributed to As5+. The EXAFS of the As K-edge revealed that there are two distinct atomic shells, As-O with the distance of 1.68 Å and As-La with the distance of 3.32 Å, indicating the formation of monodentate complex of La with AsO4
3-. Additionally, an electrostatic interaction and hydrogen bonding are also possible adsorption mechanism in acidic conditions. The SPC@La-oxalate complex adsorbent showed excellent dearsenate behavior of 1.093 mmol/g, and the maximum AsO4
3- removal was maintained in a wide pH range from 3 to 8. Sorption kinetic data were the best expressed by a pseudo-second-order rate equation, and the maximum adsorption capacity was 1.858 mmol/g based on Langmuir monolayer adsorption. Compared with previous reports, SPC@La-oxalate adsorbent could be easily prepared, and the uptake amounts for AsO4
3- were enriched. Reusability of the material after six cycles is yet another advantage to the present adsorbent. This work will help to facilitate the research on novel complex adsorbents for the removal of AsO4
3- from water..
97. Niko Dian Pahlevi, Binglin Guo, Keiko Sasaki, Immobilization of selenate in cancrinite using a hydrothermal method, Ceramics International, 10.1016/j.ceramint.2018.02.083, 44, 7, 8635-8642, 2018.05, Because of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, radioactive species were leaked out, including selenium isotopes (79Se). Developing a stable matrix that is suitable for longterm storage is necessary for the decommissioning process of the FDNPP. In the present work, the co-precipitation of SeO4 2− in cancrinite/sodalite as a potential stable matrix was investigated at various reaction times using a hydrothermal method. Over time, the SeO4 2− contents in the solid products gradually increased. The XRD patterns revealed that the reaction produced multi-phased precipitates, which were zeolite Na (P), sodalite, and cancrinite. As the SeO4 2− amount increased, the solid products were transformed to cancrinite. The calculated lattice parameter of sodalite and cancrinite showed an increase in lattice parameter a for sodalite and cancrinite, suggesting SeO4 2− incorporated into the sodalite/cancrinite structure. XRD, SEM, FTIR, 27Al-NMR, and 29Si-NMR results revealed the phase transformation of the solid products over time. Four stages of the co-precipitation mechanism are proposed, including the formation of zeolite P (Na), hydroxylation of zeolite P (Na), the formation of sodalite, and cancrinite reprecipitation..
98. Yusei Masaki, Tsuyoshi Hirajima, Keiko Sasaki, Hajime Miki, Naoko Okibe, Microbiological Redox Potential Control to Improve the Efficiency of Chalcopyrite Bioleaching , Geomicrobiol. J., 10.1080/01490451.2018.1443170, 2018.03.
99. Subbaiah Muthu Prabhu, Chitiphon Chuaicham, Keiko Sasaki, A Mechanistic Approach for the Synthesis of Carboxylate-Rich Carbonaceous Biomass-Doped Lanthanum-Oxalate Nanocomplex for Arsenate Adsorption, ACS Sustainable Chemistry & Engineering, doi/10.1021/acssuschemeng.7b04678, 6, 6052-6063, 2018.03.
100. Masahito Tanaka, Naoko Okibe, Keiko Sasaki, Factors to Enable Crystallization of Environmentally Stable Bioscorodite from Dilute As(III)-Contaminated Waters., Minerals, 2018, 8, 23., 10.3390/min8010023, 2018.03.
101. Wuhui Luo, Keiko Sasaki, Tsuyoshi Hirajima, Influence of the pre-dispersion of montmorillonite on organic modification and the adsorption of perchlorate and methyl red anions, Applied Clay Science, 10.1016/j.clay.2017.12.032, 154, 1-9, 2018.03.
102. Keiko Sasaki, Kenta Toshiyuki, Binglin Guo, Keiko Ideta, Yoshikazu Hayashi, Tsuyoshi Hirajima, Jin Miyawaki, Calcination effect of borate-bearing hydroxyapatite on the mobility of borate, Journal of Hazardous Materials, 10.1016/j.jhazmat.2017.10.003, 344, 90-97, 2018.02.
103. Niko Dian Pahlevi, Binglin Guo, Keiko Sasaki, Immobilization mechanism of selenate in cancrinite by hydrothermal method, Ceramic International, 2018.01.
104. Gde Pandhe Wisnu SUYANTARA, Tsuyoshi HIRAJIMA, Hajime MIKI, Keiko SASAKI, Floatability of molybdenite and chalcopyrite in artificial seawater, Minerals Engineering, 10.1016/j.mineng.2017.10.004, 115, 117-130, 2018.01.
105. Subbaiah Muthu Prabhu, Shunsuke Imamura, Keiko Sasaki, Mono-, di- and tri-carboxylic acid mediated lanthanum based organic frameworks: Insights into the mechanistic approach for superior adsorption of arsenate from water, ACS Sustainable Chemistry in Engineering, 2018.01.
106. Paulmanickam Koilraj and Keiko Sasaki, Eco-Friendly Alkali-Free Arginine-Assisted Hydrothermal Synthesis of Different Layered Double Hydroxides and Their Chromate Adsorption/Reduction Efficiency, Chemistry Select, 10.1002/slct.201702134, Vol. 2, Issue 32, 10459-10469, 2017.11.
107. Binglin Guo, Keiko Sasaki, Tsuyoshi Hirajima, Solidification of ettringite after uptaking selenate as a surrogate of radionuclide in glass-ceramics by using industrial by-products, Journal of Materials Science, 10.1007/s10853-017-1422-x, 52, 22, 12999-13011, 2017.11.
108. Paulmanickam Koilraj, Yuta Kamura, Keiko Sasaki, Carbon-Dot-Decorated Layered Double Hydroxide Nanocomposites as a Multifunctional Environmental Material for Co-immobilization of SeO4 2- and Sr2+ from Aqueous Solutions, ACS Sustainable Chemistry and Engineering, 10.1021/acssuschemeng.7b01979, 5, 10, 9053-9064, 2017.10.
109. Qianqian Yu, Toshihiko Ohnuki, Naofumi Kozai, Fuminori Sakamoto, Kazuya Tanaka, Keiko Sasaki, Quantitative analysis of radiocesium retention onto birnessite and todorokite, Chemical Geology, 10.1016/j.chemgeo.2017.09.008, 470, 141-151, 2017.10.
110. Binglin Guo, Keiko Sasaki, Tsuyoshi Hirajima, Selenite and selenate uptaken in ettringite
Immobilization mechanisms, coordination chemistry, and insights from structure, Cement and Concrete Research, 10.1016/j.cemconres.2017.07.004, 100, 166-175, 2017.10.
111. Binglin Guo, Keiko Sasaki, Tsuyoshi Hirajima, Characterization of the intermediate in formation of selenate-substituted ettringite, Cement and Concrete Research, 10.1016/j.cemconres.2017.05.002, 99, 30-37, 2017.09.
112. Wuhui Luo, Takeru Fukumori, Binglin Guo, Kwadwo Osseo-Asare, Tsuyoshi Hirajima, Keiko Sasaki, Effects of grinding montmorillonite and illite on their modification by dioctadecyl dimethyl ammonium chloride and adsorption of perchlorate, Applied Clay Science, https://doi.org/10.1016/j.clay.2017.06.025, Vol.146, 15, 325-333, 2017.09.
113. Wuhui Luo, Sasaki Keiko, Tsuyoshi Hirajima, Necessity of pre-dispersion of montmorillonite for its organic modification and the influence on adsorption of perchlorate and methyl red by modified composites, Applied Clay Science, 2017.08.
114. Binglin Guo, Sasaki Keiko, Tsuyoshi Hirajima, Selenite and selenate uptaken in ettringite: Immobilization mechanisms, coordination chemistry and insights from structure, Concrete and Cement Research, 2017.07.
115. Bigling Guo, Sasaki Keiko, Tsuyoshi Hirajima, Structural transformation of selenate ettringite: a hint for exfoliation chemistry, RSCAdvances, 10.1039/c7ra08765a, 7, 42407-42415, 2017.06.
116. Paulmanickam Koilraj, Keiko Sasaki, Selective removal of phosphate using La-porous carbon composites from aqueous solutions
Batch and column studies, Chemical Engineering Journal, 10.1016/j.cej.2017.02.075, 317, 1059-1068, 2017.06.
117. Binglin Guo, Sasaki Keiko, Tsuyoshi Hirajima, Characterization of an intermediate in formation of selenate-substituted ettringite, Cement and Concrete Research, http://dx.doi.org/10.1016/j.cemconres.2017.05.002, 99, 30-37, 2017.05.
118. Binglin Guo, Sasaki Keiko, Tsuyoshi Hirajima, Solidification of ettringite after uptaking selenate as a surrogate of radionuclide in glass-ceramics by using industrial byproducts, Journal of Material Sciences, in press, 2017.05.
119. Xiangchun Liu, Tsuyoshi Hirajima, Moriyasu Nonaka, Keiko Sasaki, Experimental study on freeze drying of Loy Yang lignite and inhibiting water re-adsorption of dried lignite, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 10.1016/j.colsurfa.2017.01.076, Vol.520, 146-153, 2017.05.
120. Subbaiah Muthu Prabhu, Paulmanickam Koilraj, Sasaki Keiko, Synthesis of sucrose-derived amorphous carbon-doped ZrxLa1-xOOH materials and their superior performance for the simultaneous depollution of arsenite and fluoride from binary systems, Chemical Engineering Journal, doi.org/10.1016/j.cej.2017.05.052, 325, 1-13, 2017.04.
121. Paulmanickam Koilraj, Sasaki Keiko, Biomolecule-assisted interlayer anion-controlled layered double hydroxide as an efficient sorbent for arsenate removal, Journal of Materials Chemistry A, in press, 2017.04.
122. Wuhui Luo, Tsuyoshi Hirajima, Keiko Sasaki, Selective adsorption of inorganic anions on unwashed and washed hexadecyl pyridinium-modified montmorillonite, Separation and Purification Technology, 10.1016/j.seppur.2016.12.004, 176, 120-125, 2017.04.
123. Kojo T. Konadu, Keiko Sasaki, Takashi Kaneta, Grace Ofori-Sarpong, Kwadwo Osseo-Asare, Bio-modification of carbonaceous matter in gold ores
Model experiments using powdered activated carbon and cell-free spent medium of Phanerochaete chrysosporium, Hydrometallurgy, 10.1016/j.hydromet.2016.08.003, 168, 76-83, 2017.03.
124. Naoko Okibe, Shiori Morishita, Masahito Tanaka, Keiko Sasaki, Tsuyoshi Hirajima, Kazuhiro Hatano, Atsuko Ohata, Bioscorodite crystallization using Acidianus brierleyi
Effects caused by Cu(II) present in As(III)-bearing copper refinery wastewaters, Hydrometallurgy, 10.1016/j.hydromet.2016.07.003, 168, 121-126, 2017.03.
125. Paulmanickam Koilraj, Sasaki Keiko, Selective removal of phosphate using La-porous carbon composites from aqueous solutions: Batch and column studies, Chemical Engineering Journal, doi.org/10.1016/j.cej.2017.02.075, 317, 1059-1068, 2017.02.
126. Sasaki Keiko, Kenta Toshiyuki, Binglin Guo, Tsuyoshi Hirajima, Calcination effect of borate-bearing hydroxyapatite on mobility of borate, J Hazard Mater, 2017.02.
127. Subbaiah Muthu Prabhu, Sasaki Keiko, Fabrication of chitosan-reinforced ZrxAl1-xOOH nanocomposites and their arsenite and fluoride depollution densities from single/binary systems, Chemistry Select, in press., 2017.02.
128. Wuhui Luo, Akihiro Inoue, Tsuyoshi Hirajima, Keiko Sasaki, Synergistic effect of Sr2+ and ReO4 adsorption on hexadecyl pyridinium-modified montmorillonite, Applied Surface Science, 10.1016/j.apsusc.2016.10.135, 394, 431-439, 2017.02.
129. Kojo Twum-Knadu, Sasaki Keiko, Takashi Kaneta, Grace Ofori-Sarpong, Kwadwo Osseo-Asare, Bio-modification of carbonaceous matters in gold ore: Model experiments using powdery activated charcoal and cell-free extracts of Phanerochaete chrysosporium, Hydrometallurgy, 168 (2017) 76–83, 2017.01.
130. Wuhui Luo, Tsuyoshi Hirajima, Sasaki Keiko, Selective adsorption of inorganic anions on unwashed and washed hexadecyl pyridinium-modified montmorillonite, Separation and Purification Technology , 176, 120-125, 2017.01.
131. Wuhui Luo, Akihiro Inoue, Tsuyoshi Hirajima, Sasaki Keiko, Synergistic effect on binary adsorption system of Sr2+ and ReO4- as radionuclide surrogates by hexadecyl pyridinium-modified montmorillonite, Applied Surface Science, http://dx.doi.org/10.1016/j.apsusc.2016.10.135, 394, 431-439, 2017.01.
132. Sasaki Keiko, Shugo Nagato, Keiko Ideta, Jin Miyawaki, Tsuyoshi Hirajima, Enhancement of fluoride removal by co-precipitation with Al-substituted hydroxyapatite, Chem. Engng. J., doi.org/10.1016/j.cej.2016.11.096, 311, 284-292, 2017.01.
133. Tsuyoshi Hirajima, Hajime Miki, Gde Pandhe Wisnu Suyantara, Sasaki Keiko, Selective flotation of chalcopyrite and molybdenite with H2O2 oxidation, Minerals Engineering, 100, 83-92, 2017.01.
134. Dewi Agustina Iryani, Satoshi Kumagai, Moriyasu Nonaka, Keiko Sasaki, Tsuyoshi Hirajima, Characterization and Production of Solid Biofuel from Sugarcane Bagasse by Hydrothermal Carbonization, Waste and Biomass Valorization, 10.1007/s12649-017-9898-9, 8, 6, 1941-1951, 2017.01.
135. Subbaiah Muthu Prabhu, Keiko Sasaki, Fabrication of Chitosan-Reinforced ZrxAl1-xOOH Nanocomposites and Their Arsenite and Fluoride Depollution Densities from Single/Binary Systems, ChemistrySelect, 10.1002/slct.201701072, 2, 22, 6375-6387, 2017.01.
136. Paulmanickam Koilraj, Keiko Sasaki, Kannan Srinivasan, Novel biomolecule-assisted interlayer anion-controlled layered double hydroxide as an efficient sorbent for arsenate removal, Journal of Materials Chemistry A, 10.1039/c7ta03056h, 5, 28, 14783-14793, 2017.01.
137. Tsuyoshi Hirajima, Hajime Miki, Gde Pandhe Wisnu Suyantara, Hidekazu Matsuoka, Ahmed Mohamed Elmahdy, Keiko Sasaki, Yuji Imaizumi, Shigeto Kuroiwa, Selective flotation of chalcopyrite and molybdenite with H2O2 oxidation, Minerals Engineering, 10.1016/j.mineng.2016.10.007, 100, 83-92, 2017.01.
138. Sayo Moriyama, Keiko Sasaki, Tsuyoshi Hirajima, Effect of freeze drying on characteristics of Mg–Al layered double hydroxides and bimetallic oxide synthesis and implications for fluoride sorption, Applied Clay Science, https://doi.org/10.1016/j.clay.2016.07.016, Vol.132-133, 460-467, 2016.11.
139. Qianqian YU, Sasaki Keiko, Microwave-assisted hydrothermal synthesis of nanocrystalline lithium-ion sieve from biogenic manganese oxide, its characterization and lithium sorption studies, Hydrometallurgy, 10.1016/j.hydromet.2015.10.002, Vol.165, Part1, 118-124, 165 (2016) 118–124, 2016.10.
140. Chenyang Li, Lazaro Calderin, Sasaki Keiko, Ismaila Dabo, First-principles Study of the Removal of Boron by Co-precipitation with Hydroxyapatite Using Dolomite as a Starting Material, Bulletin of the American Physical Society, 2016.10.
141. KOILRAJ PAULMANICKAM, Siwaporn Meejoo Smith, Qianqian Yu, Taichi Momoki, Sarah Ulrich, Sasaki Keiko, Encapsulation of powdery spinel type of Li+ ion sieve derived from biogenic manganese oxide in alginate beads, Powder Technology, http://dx.doi.org/10.1016/j.powtec.2016.08.009, 301 (2016) 1201–1207, 2016.08.
142. Sasaki Keiko, Kenta Toshiyuki, Keiko Ideta, Jin Miyawaki, Tsuyoshi Hirajima, Interfacial effects of MgO in hydroxylated calcined dolomite on the co-precipitation of borates with hydroxyapatite, Colloids and Surfaces A: Physicochemical and Engineering Aspects, doi.org/10.1016/j.colsurfa.2016.05.044, 504 (2016) 1–10, 2016.07.
143. Xiangchun Liu, Tsuyoshi Hirajima, Sasaki Keiko, Effects of hydrothermal treatment coupled with mechanical expression on combustion performance of Loy Yang lignite, Journal of Thermal Analysis and Calorimetry, 2016.07.
144. Hajime Miki, Tsuyoshi Hirajima, Sasaki Keiko, Catalytic effect of silver on arsenic-containing copper sulfide dissolution in acidic solution, Hydrometallurgy, https://doi.org/10.1016/j.hydromet.2016.02.007, Vol.162, 1-8, 2016.06.
145. KOILRAJ PAULMANICKAM, Yu Takaki, Sasaki Keiko, Adsorption characteristics of arsenate on colloidal nanosheets of layered double hydroxide, Applied Clay Science, 134 (2016) 110–119, 2016.06.
146. Tsuyoshi Hirajima, Gde Pandhe Wisnu Suyantara, Hajime Miki, Sasaki Keiko, Effect of Mg2+ and Ca2+ as divalent seawater cations on the floatability of molybdenite and chalcopyrite, Minerals Engineering, 96–97 (2016) 83–93, 2016.06.
147. Tsuyoshi Hirajima, Takao Hagino, Sasaki Keiko, Recovery and Upgrading of Phosphorus from Digested Sewage Sludge as MAP by Physical Separation Techniques, Journal of Environmental Protection, doi.org/10.4236/jep.2016.76074, 7, 816-824, 2016.06.
148. Yu Takaki, Xinhong Qiu, Tsuyoshi Hirajima, Keiko Sasaki, Removal mechanism of arsenate by bimetallic and trimetallic hydrocalumites depending on arsenate concentration, Applied Clay Science, 134 (2016) 26–33, 2016.05.
149. Naoko Okibe, Yusei Masaki, Daisuke Nakayama, Sasaki Keiko, Microbial recovery of vanadium by the acidophilic bacterium, Acidocella aromatic, Biotechnology Letters, DOI: 10.1007/s10529-016-2131-2, 38:1475–1481, 2016.05.
150. Wuhui Luo, Tsuyoshi Hirajima, Sasaki Keiko, Optimization of Hexadecylpyridinium-modified Montmorillonite for Removal of Perchlorate Based on Adsorption Mechanisms, Applied Clay Science, https://doi.org/10.1016/j.clay.2016.01.005, Vol.123, 29-36, 2016.04.
151. Dewi Agustina Iryani, Sasaki Keiko, Tsuyoshi Hirajima, HYDROTHERMAL CARBONIZATION KINETICS OF SUGARCANE BAGASSE TREATED BY HOT COMPRESSED WATER UNDER VARIABEL TEMPERATURE CONDITIONS, ARPN Journal of Engineering and Applied Sciences, 11, 7, 4833-4839, 2016.04.
152. Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, Hajime Miki, Sasaki Keiko, EFFECT OF KEROSENE EMULSION IN MgCl2 SOLUTION ON THE KINETICS OF BUBBLE INTERACTION WITH MOLYBDENITE AND CHALCOPYRITE, Colloids and Surfaces A: Physicochemical and Engineering Aspects, in press., 501 (2016) 98–113, 2016.04.
153. Yusei Masaki, Masashi Maki, Daisuke Nakayama, Sasaki Keiko, Naoko Okibe, Microbial recovery of vanadium by Fe(III)-reducing, acidophilic bacterium, Acidocella aromatica PFBC, Biotechnology Letters, 2016.04.
154. Xiangchun Liu, Tsuyoshi Hirajima, Sasaki Keiko, Effect of hydrothermal treatment coupled with mechanical expression on equilibrium water content of Loy Yang lignite and mechanism, Mater. Trans., in press., 2016.04.
155. Airi Harada, Sasaki Keiko, Takashi Kaneda, Direct Determination of Lignin Peroxidase Released from Phanerocheate chrysosprium by In-Capillary Enzyme Assay Using Micellar Electrokinetic Chromatography, Journal of Chromatography A, 1440 (2016) 145–149, 2016.02.
156. Tomoyo Goto, Sasaki Keiko, Synthesis of morphologically controlled hydroxyapatite from fish bone by urea-assisted hydrothermal treatment and its Sr2+ sorption capacity, Powder Technology, 292, 314-322, 2016.02.
157. KOILRAJ PAULMANICKAM, Sasaki Keiko, Fe3O4/MgAl-NO3 layered double hydroxide as magnetically separable sorbent for the remediation of aqueous phosphate, J. Environ. Chem. Engng., http://dx.doi.org/10.1016/j.jece.2016.01.005, 4, 984-991, 2016.01.
158. Sasaki Keiko, Tsuyoshi Hirajima, Kenta Toshiyuki, Dabo Ismaila, Mistuhiro Murayama, Removal mechanism of high concentration borate by co-precipitation with hydroxyapatite, Journal of Environmental Chemical Engineering, http://dx.doi.org/10.1016/j.jece.2016.01.012, 4, 1092-1101, 2016.01.
159. Wuhui Luo, Akihiro Inoue, Tsuyoshi Hirajima, Sasaki Keiko, Sequential modification of montmorillonite with dimethyl dioctadecyl ammonium chloride and benzyl octadecyl dimethyl ammonium chloride for removal of perchlorate, Microporous Mesoporous Materials, http://dx.doi.org/10.1016/j.micromeso.2015.12.030, 233 (2016) 117-124, 2016.01.
160. Mutia Dewi YUNIATI, Keitaro KITAGAWA, Tsuyoshi HIRAJIMA, Hajime MIKI, Naoko OKIBE, Keiko SASAKI, Suppression of pyrite oxidation in acid mine drainage by carrier microencapsulation using liquid product of hydrothermal treatment of low-rank coal, and electrochemical behavior of resultant encapsulating coatings, Hydrometallurgy, https://doi.org/10.1016/j.hydromet.2015.09.028, Vol.158, 83-93, 2015.12.
161. Kojo Twum-Knadu, Sasaki Keiko, Grace OFORI-SARPONG, Kwadwo Osseo-Asare, Takashi Kaneta, Activated carbon as surrogate for carbonaceous matter in gold ores: Degradation via enzyme treatment, Journal of the African Materials Research Society, in press, 2015.12.
162. Xinhong Qiu, Sasaki Keiko, Removal mechanism of polymeric borate by calcined layered double hydroxides containing different divalent metals, Colloids and Surfaces A: Physicochemical and Engineering Aspects, https://doi.org/10.1016/j.colsurfa.2015.07.036, Vol.482, 702-709, 2015.10.
163. Kenta Toshiyuki, Shugo Nagato, Tsuyoshi Hirajima, Sasaki Keiko, Takuro Naruse, Takeshi Kawashima, Influence of Mg components in hydroxylated calcined dolomite to (co-)precipitation of fluoride with apatites, Chem. Engng. J., 10.1016/j.cej.2015.10.029, 285, 487-496, 2015.10.
164. Widi Astuti, Tsuyoshi Hirajima, Sasaki Keiko, Naoko Okibe, Comparison of effectiveness of citric acid and other acids in leaching of different Indonesian low-grade saprolitic ores, Minerals Engineering,, doi:10.1016/j.mineng.2015.10.001, 85, 1-16, 2015.10.
165. Mari YOSHIDA, Paulmanickam KOILRAJ, Xinhong QIU, Tsuyoshi HIRAJIMA, Keiko SASAKI, Sorption of arsenate on MgAl and MgFe layered double hydroxides derived from calcined dolomite, Journal of Environmental Chemical Engineering, https://doi.org/10.1016/j.jece.2015.05.016, Vol.3, Issue 3, 1614-1621, 2015.09.
166. Wuhui Luo, Keiko Sasaki, Tsuyoshi Hirajima, Surfactant-modified montmorillonite by benzyloctadecyldimethylammonium chloride for removal of perchlorate, Colloids and Surfaces A: Physicochemical and Engineering Aspects, https://doi.org/10.1016/j.colsurfa.2015.06.025, 481, 616-625, 2015.09.
167. Liu Xiangchun, Tsuyoshi Hirajima, Sasaki Keiko, Investigation of the Changes in Hydrogen Bonds During Low-Temperature Pyrolysis of Lignite by Diffuse Reflectance FT-IR Combined with Forms of Water, Industrial & Engineering Chemistry Research, in press, 2015.09.
168. Widi ASTUTI, Tsuyoshi Hirajima, Sasaki Keiko, Naoko Okibe, Kinetics of Nickel Extraction from Indonesian Saprolitic Ores by Citric Acid Leaching under Atmospheric Pressure, Minerals & Metallurgical Processing Journal, Vol.32, No.3, in press, 2015.08.
169. Mutia Dewi YUNIATI, Tsuyoshi Hiraji, Hajime Miki, Sasaki Keiko, Silicate Covering Layer on Pyrite Surface in the Presence of Silicon-Catechol Complex for Acid Mine Drainage Prevention, Materials Transactions, https://doi.org/10.2320/matertrans.M-M2015821, Vol.56, Issue 10, 1733-1741, 2015.08.
170. Sayo Moriyama, Sasaki Keiko, Tsuyoshi Hirajima, Sorption properties of boron on Mg–Al bimetallic oxides calcined at different temperatures, Separation and Purification Technology, 152, 192-199, 2015.08.
171. Wuhui Luo, Sasaki Keiko, Tsuyoshi Hirajima, Effect of surfactant molecular structure on perchlorate removal by various surfactant-modified montmorillonites, Applied Clay Science, 114, 212-220, 2015.06.
172. Moriyasu NONAKA, Tsuyoshi HIRAJIMA, Satoshi KUMAGAI,Keiko SASAKI, Hydrothermal Treatment of Lignite for CO2 Gasification, Journal of MMIJ, Vol.131, No.5, 219-225, 2015.05.
173. Naoko Okibe, Kiyomasa Sueishi, Mikoto Koga, Yusei Masaki, Tsuyoshi Hirajima, Sasaki Keiko, Selenium (Se) Removal from Copper Refinery Wastewater Using a Combination of Zero-Valent Iron (ZVI) and Se(VI)-Reducing Bacterium,Thauera selenatis, Materials Transactions, 2015.04.
174. Xinhong Qiu, Sasaki Keiko, Yu Takaki, Tsuyoshi Hirajima, Keiko IDETA, Jin Miyawaki, Mechanism of boron uptake by hydrocalumite calcined at different temperatures, Journal of Hazardous Materials, 10.1016/j.jhazmat.2015.01.066, Vol.287, 268-277, 2015.04.
175. Xiangchun Liu, Tsuyoshi Hirajima, Moriyasu Nonaka, Anggoro T Mursito, Sasaki Keiko, Use of FT-IR combined with forms of water to study of the changes in hydrogen bonds during low-temperature heating of lignite, Drying Technology, in press, 2015.03.
176. Yusei Masaki, Tsuyoshi Hirajima, Keiko Sasaki, Naoko Okibe, Bioreduction and Immobilization of Hexavalent Chromium by the Extremely Acidophilic Fe(III)‑reducing Bacterium Acidocella aromatica Strain PFBC, Extremophiles, doi: 10.1007/s00792-015-0733-6, Vol.19, Issue 2, pp.495-503, 2015.03.
177. Wuhui LUO, Keiko SASAKI, Tsuyoshi HIRAJIMA, Evaluation of BDTAC, DDAC and BDOAC-modified Montmorillonites for Perchlorate Removal, Fourth International Conference on Multifunctional, Hybrid and Nanomaterials, P1.247, 2015.03.
178. Xinhong Qiu, Sasaki Keiko, Kwadwo Osseo-Asare, Tsuyoshi Hirajima, Keiko IDETA, Jin Miyawaki, Sorption of H3BO3/B(OH)4- on calcined LDHs including different divalent metals , Journal of Colloid and Interface Science, 445, 183-194, 2015.01.
179. Xinhong Qiu, Mari Yoshida, Tsuyoshi Hirajima, Sasaki Keiko, Rapid synthesis of LDHs by using dolomite as a magnesium source and its application in borate removal , Materials Transactions, 2015.01.
180. Tsuyoshi Hirajima, Masanori Mori, Sasaki Keiko, Osamu Ichikawa, Hajime Miki, Mohsen Farahat, Mitsuru Sawada, Selective flotation of chalcopyrite and molybdenite with plasma pre-treatment, Minerals Engineering, doi.org/10.1016/j.mineng.2014.07.011, Vol.66-68, 102-111, 2014.11.
181. Masahito Tanaka, Yuta Yamaji, Yuken Fukano, Kazuhiko Shimada, Junichiro Ishibashi, Tsuyoshi Hirajima, Sasaki Keiko, Mitsuru Sawada, Naoko Okibe, Biooxidation of gold-, silver, and antimony-bearing highly refractory polymetallic sulfide concentrates, and its comparison with abiotic pre-treatment techniques, Geomicrobiology Journal, DOI:10.1080/01490451.2014.981645, 2014.11.
182. Sasaki Keiko, Qianqian Yu, Taichi Momoki, Takuya Kaseyama, Adsorption characteristics of Cs+ ions onto biogenic birnessite, Applied Clay Science, 10.1016/j.clay.2014.06.028, Vol.101, 2014.11.
183. Takeshi Tsuruta, Daishi UMENAI, Tomonobu HATANO, Tsuyoshi Hirajima, Sasaki Keiko, Screening Micro-organisms for Cadmium Absorption from Aqueous Solution and Cadmium Absorption Properties of Arthrobacter nicotianae., Bioscience, Biotechnology, and Biochemistry, doi.org/10.1080/09168451.2014.930321, Vol.78, Issue 10, 1791-1796, 2014.10.
184. Qianqian Yu, Sasaki Keiko, In situ X-ray diffraction investigation of the evolution of a nanocrystalline lithium-ion sieve from biogenic manganese oxide, Hydrometallurgy, 10.1016/j.hydromet.2014.07.002, Vol.150, 253-258, 2014.10.
185. Takehiko TSURUTA, Daishi UMENAI, Tomonobu HATANO, Tsuyoshi HIRAJIMA, Keiko SASAKI, Screening Micro-organisms for Cadmium Absorption from Aqueous Solution and Cadmium Absorption Properties of Arthrobacter nicotianae, Bioscience, Biotechnology, and Biochemistry, http://dx.doi.org/10.1080/09168451.2014.930321, Vol. 78, Issue 10, pp.1791-1796, 2014.10.
186. Tomoyo Goto, Sasaki Keiko, Effect of trace elements in fish bones on crystal characteristics of hydroxyapatite obtained by calcination, Ceramics International, 10.1016/j.ceramint.2014.03.067, Vol.40, Issue 7, PartB, 10777-10785, 2014.08.
187. M.A. Halim, Ratan K. Majumder, G.Rasul, Yoshinari HIROSHIRO, Sasaki Keiko, J. Shimada, Kenji Jinno, Geochemical Evaluation of Arsenic and Manganese in Shallow Groundwater and Core Sediment in Singair Upazila, Central Bangladesh, Arabian Journal for Science and Engineering, Vol.39, Issue 7, 5585-5601, in press, 2014.07.
188. Hisaya TSUJI, Pilasinee LIMSUWAN, Tsuyoshi HIRAJIMA, Keiko SASAKI, Hajime MIKI, Satoshi KUMAGAI, Recovery of Furfural Produced by Hydrothermal Treatment with Biomass Charcoal, International Journal of Environment, Vol.4, No.1, pp.11-17, 2014.06.
189. Naoki Higashidani, Takashi Kaneta, Nobuyuki Takeyasu, Shoji Motomizu, Naoko Okibe, Sasaki Keiko, Speciation of arsenic in a thermoacidophilic iron-oxidizing archaeon, Acidianus brierleyi, and its culture medium by inductively coupled plasma-optical emission spectroscopy combined with flow injection pretreatment using an anion-exchange mini-column, Talanta, 122, 240-245, 2014.05.
190. Sasaki Keiko, Tomoyo Goto, Immobilization of Sr2+ on Naturally Derived Hydroxyapatite by Calcination of Different Species of Fish Bones and Influence of Calcination on Ion-exchange Efficiency, Ceramics International, 10.1016/j.ceramint.2014.03.169, Vol.40, Issue 8, Part A, 11649-11656, 2014.04.
191. Takehiko Tsuruta, Keiko Sasaki, Screening Microorganisms for Cadmium Absorption from Aqueous Solution and the Cadmium Absorption Properties of Arthrobacter nicotianae, Bioscience, Biotechnology, and Biochemistry, in press, 2014.04.
192. Naoko Okibe, Masaharu Koga, Shiori Morishita, Masahito Tanaka, Shinichi HEGURI, Satoshi ASANO, Sasaki Keiko, Tsuyoshi Hirajima, Microbial formation of crystalline scorodite for treatment of As(III)-bearing copper refinery process solution using Acidianus brierleyi, Hydrometallurgy, 143, 34-41, 2014.03.
193. Keiko Sasaki, Xinhong Qiu, Jin Miyawaki, Keiko Ideta, Hitoshi Takamori, Sayo Moriyama, Tsuyoshi hirajima, Contribution of boron-specific resins containing N-methylglucamine groups to immobilization of borate/boric acid in a permeable reactive barrier comprising agglomerated MgO, Desalination, 10.1016/j.desal.2013.11.018, Vol.337, 17, 109-116, 2014.03.
194. Xinhong QIU, Keiko SASAKI, Tsuyoshi HIRAJIMA, Keiko IDETA, Jin MIYAWAKI, One-step Synthesis of Layered Double Hydroxide-intercalated Gluconate for Removal of Borate, Separation and Purification Technology, DOI: 10.1016/j.seppur.2013.12.031. ISSN: 1383-5866., Vol.123, pp.114–123, 2014.02.
195. Xinhong Qiu, Sasaki Keiko, Tsuyoshi Hirajima, Keiko IDETA, Jin Miyawaki, Sorption of borate onto layered double hydroxides assembled in filter papers through in situ hydrothermal crystallization, Applied Clay Science, Vol.88-89, 134-143, 2014.02.
196. Sayo MORIYAMA, Keiko SASAKI, Tsuyoshi HIRAJIMA, Effect of Calcination Temperature on Mg-Al Bimetallic Oxides as Sorbents for the Removal of F- in Aqueous Solutions, Chemosphere, 10.1016/j.chemosphere.2013.10.018, Vol.95, pp.597-603, 2014.01.
197. Sasaki Keiko, Sayo Moriyama, Effect of calcination temperature for magnesite on interaction of MgO-rich phases with boric acid, Ceramics International, 10.1016/j.ceramint.2013.07.056., Vol.40, Issue 1, PartB, 1651-1660, 2014.01.
198. M. A. Halim, R. K. Majumder, M. N. Zaman, S. Hossain, M. G. Rasul, Sasaki Keiko, Mobility and impact of trace metals in Barapukuria coal mining area, Northwest Bangladesh, Arabian Journal of Geoscience, DOI 10.1007/s12517-012-0769-1, Vol.6, Issue 12, 4593-4605, 2013.12.
199. Qianqian Yu, Keiko Sasaki, Tsuyoshi Hirajima, Bio-templated synthesis of lithium manganese oxide microtubes and their application in Li+ recovery, Journal of Hazardous Materials, doi:10.1016/j.jhazmat.2013.08.027, Vol.262, 15, PP.38-47, 2013.11.
200. Sasaki Keiko, Mari Yoshida, Bashir Ahmmad Arima, Naoyuki Fukumoto, Tsuyoshi Hirajima, Sorption of fluoride on partially calcined dolomite, Colloids and Surfaces A: Physicochemical and Engineering Aspects, doi.org/10.1016/j.colsurfa.2012.11.039, Vol.435, 56-62, 2013.10.
201. Qianqian YU, Emiko MORIOKA, Keiko SASAKI, Characterization of Lithium Ion Sieve Derived from Biogenic Mn Oxides, Microporous and Mesoporous Materials, http://dx.doi.org/10.1016/j.micromeso.2013.05.026, Vol.179, pp.122–127, 2013.09.
202. Naoko OKIBE, Masashi MAKI, Keiko SASAKI, Tsuyoshi HIRAJIMA, Mn(Ⅱ)-Oxidizing Activity of Pseudomonas sp. Strain MM1 is Involved in the Formation of Massive Mn Sediments around Sambe Hot Springs in Japan, Materials Transactions, Vol.54, No.10, pp.2027-2031, 2013.09.
203. Naoko Okibe, Masashi Maki, Keiko Sasaki, Tsuyoshi Hirajima, Mn(II)-oxidizing activity of Pseudomonas sp. strain MM1 is involved in the formation of massive Mn sediments around Sambe hot springs in Japan, Materials Transactions, in press, 2013.08.
204. Kazuya Tanaka, Qianqian Yu, Keiko Sasaki, Toshihiko Ohnuki, Cobalt(II) oxidation by biogenic Mn oxide produced by Pseudomonas sp. strain NGY-1, Geomicrobiology Journal, 10.1080/01490451.2013.791352, Vol.30, Issue 10, 874-885, 2013.08.
205. Sasaki Keiko, Qiu Xinhong, Sayo Mortiyama, Chiharu Tokoro, Keiko Ideta, Jin Miyawaki, Characteristic sorption of H3BO3/B(OH)4– on magnesium oxide, Materials Transactions, DOI: 10.2320/matertrans.M-M2013814, Vol.54, No.9, 1809-1817, 2013.08.
206. YU QIANQIAN, Keiko Sasaki, Kazuya TANAKA, Toshihiko OHNUKI, Tsuyoshi Hirajima, Zinc Sorption During Bio-oxidation and Precipitation of Manganese Modifies the Layer Stacking of Biogenic Birnessite, Geomicrobiology Journal, Vol.30, Issue 9, 829-839, 2013.07.
207. Naoko Okibe, Masaharu KOGA, Shinichi HEGURI, Satoshi ASANO, Keiko Sasaki, Tsuyoshi Hirajima, Simultaneous Oxidation and Immobilization of Arsenite from Refinery Waste Water by Thermoacidophilic Iron-oxidizing Archaeon, Acidianus brierleyi, Minerals Engineering, http://dx.doi.org/10.1016/j.mineng.2012.08.009, 48, 126-134, 2013.07.
208. Xinhong Qiu, Sasaki Keiko, Tsuyoshi Hirajima, Keiko IDETA, Jin Miyawaki, Temperature effect on the sorption of borate by a layered double hydroxide prepared using dolomite as a magnesium source, Chemical Engineering Journal, doi.org/10.1016/j.cej.2013.03.099, Vol.225, 664-672, 2013.06.
209. Keiko Sasaki, Xinhong Qiu, Yukiho Hosomomi, Sayo Moriyama, Tsuyoshi Hirajima, Effect of natural dolomite calcination temperature on sorption of borate onto calcined products, Microporous and Mesoporous Materials, 10.1016/j.micromeso.2012.12.029, Vol.171, 1-8, 2013.05.
210. Qianqain YU, Emiko Morioka, Sasaki Keiko, Synthesis of lithium ion sieve derived from biogenic Mn oxides, Microporous Mesoporous Materials, 10.1016/j.micromeso.2013.05.026, 179, 122-127, 2013.05.
211. Keiko Sasaki, Yoshitaka UEJIMA, Atsushi SAKAMOTO, Qianqian Yu, Junichiro Ishibashi, Naoko Okibe, Tsuyoshi Hirajima, Geochemical and Microbiological Analysis of Sambe hot springs, Shimane Prefecture, Japan, Resource Geology, DOI: 10.1111/rge.12002, Vol.63, Issue 2, 155-165, 2013.04.
212. Sayo Moriyama, Sasaki Keiko, Tsuyoshi Hirajima, Effect of calcination temperatures on Mg–Al bimetallic oxides as sorbents for the removal of F− in aqueous solutions, Chemosphere, doi.org/10.1016/j.chemosphere.2013.10.018, in press, 2013.03.
213. Xinhong Qiu, Sasaki Keiko, Tsuyoshi Hirajima, 宮脇 仁, 出田圭子, One-Step Synthesis of layer double hydroxide-intercalated gluconate for borate removal, Separation and Purification Technology, in press, 2013.03.
214. Moriyasu Nonaka, Tsuyoshi Hirajima, Keiko Sasaki, Gravity separation and its effect on CO2 gasification, Fuel, org/10.1016/j.fuel2011.10.074, Vol.103, 37-41, 2013.01.
215. Dewi Agustina IRYANI, 熊谷 聡, Moriyasu Nonaka, Yoshinobu NAGASHIMA, Keiko Sasaki, Tsuyoshi Hirajima, Hot Compressed Water Treatment of Solid Waste Material from the Sugar Industry for Valuable Chemical Production, International Journal of Green Energy , DOI:10.1080/15435075.2013.777909, in press, 2012.12.
216. Sayo Moriyama, Keiko Sasaki, Tsuyoshi Hirajima, Effect of calcination temperatures in producing Mg–Al bimetallic oxides as sorbents for the removal of F− in aqueous solutions, Separation and Purification Technology, 2012.09.
217. Keiko Sasaki, Naoyuki FUKUMOTO, Sayo MORIYAMA, YU QIANQIAN, Tsuyoshi Hirajima, Chemical Regeneration of Magnesium Oxide Used as a Sorbent for Fluoride, Separation and Purification Technology, Vol.98, p.24-p.30, Vol.98. pp.24-30
, 2012.09.
218. Qianqian YU, Keiko Sasaki, Kazuya Tanaka, Toshihiko Ohnuki, Tsuyoshi Hirajima, Structural influences of zinc on the biogenic manganese oxides and concomitant formation of MnO2 nanosheets, Geomicrobiology Journal, 2012.08.
219. Keiko Sasaki, Shoichi Tsuruyama, Sayo Moriyama, Stephanie Handley-Sidhu, Joanna C. Renshaw, Lynne E. Macaskie, Ion Exchange Capacity of Sr2+ onto Calcined Biological Hydroxyapatite
and Implications for Use in Permeable Reactive Barriers, Materials Transactions,, 53, 7, 1267-1272, 2012.07.
220. Qianqian Yu, Keiko Sasaki, Kazuya Tanaka, Toshihiko Ohnuki, Tsuyoshi Hirajima, Structural factors of biogenic birnessite produced by fungus Paraconiothyrium sp.
WL-2 strain affecting sorption of Co2+, Chemical Geology, doi:10.1016/j.chemgeo.2012.03.029, 310-311, 106-113, 2012.07.
221. Keiko SASAKI, Naoyuki FUKUMOTO, Sayo MORIYAMA, Qianqian YU, Tsuyoshi HIRAJIMA, Chemical regeneration of magnesium oxide as a sorbent of fluoride, Separation and Purification Technology, 98, 24-30, 2012.07.
222. Keiko Sasaki, Koichiro Takatsugi, Olli H. Tuovinen, Spectroscopic analysis of the bioleaching of chalcopyrite by Acidithiobacillus caldus, Hydrometallurgy, 127-128, 116-120, 2012.07.
223. YU QIANQIAN, Keiko Sasaki, Kazuya TANAKA, Toshihiko OHNUKI, Tsuyoshi Hirajima, Structural Factors of Biogenic Birnessite Produced by Fungus Paraconiothyrium sp. WL-2 Strain Affecting Sorption of Co2+, Chemical Geology, doi: 10.1016/j.chemgeo.2012.03.029 Vol.310-311, 5, 106-113, 5, pp.106–113, 2012.06.
224. Tsuyoshi Hirajima, Yuki AIBA, Mohsen Farahat, Naoko Okibe, Keiko Sasaki, Takehiko Tsuruta, Katsumi DOI, Effect of Microorganisms on Flocculation of Quartz, International Journal of Mineral Processing, doi:10.1016/j.minpro.2011.10.001, Vol.102-103, 107-111, 2012.01.
225. Himawan Tri Bayu Murti PETRUS, Tsuyoshi Hirajima, Keiko Sasaki, Hideyuki OKAMOTO, Effects of Sodium Thiosulphate on Chalcopyrite and Tennantite; An Insight for Alternative Separation Technique, International Journal of Mineral Processing, dx.doi.org/10.1016/j.minpro.2011.11.002, Vol.102–103, 116-123, 2012.01.
226. Characterization of passivation layers in bioleaching of sulfides.
227. Naoyuki Fukumoto, Keiko Sasaki, Sayo Moriyama, Tsuyoshi Hirajima, Synthesis of Magnesia as a Reusable Sorbent for Fluoride, Journal of Novel Carbon Resource Sciences, 4, 32-35, 2011.09.
228. Handley-Sidhu S, Renshaw J.C, Sayo MORIYAMA, Stolpe B, Yong P, Mennan C, Bagheriasl S, Stamboulis A, Paterson-Beedle M, Keiko SASAKI, Pattrick R.A.D, Lead J.R, Macaskie L.E., Removal of Sr2+ and Co2+ into Biogenic Hydroxyapatite: Implications for Biomineral Ion Exchange Synthesis, Environmental Science and Technology, 45, 6985-6990, 2011.07.
229. Koichiro Takatsugi, Keiko Sasaki, Tsuyoshi Hirajima, Mechanism of the enhancement of bioleaching of copper from enargite by thermophilic iron-oxidizing archaea with the concomitant precipitation of arsenic, Hydrometallurgy, 10.1016/j.hydromet.2011.05.013, 109, 90-96, 2011.05.
230. Keiko Sasaki, Koichiro Takatsugi, Tsuyoshi Hirajima, Effects of initial Fe2+ concentration and pulp density on the bioleaching of Cu from enargite by Acidianus brierleyi, Hydrometallurgy, 10.1016/j.hydromet.2011.06.008, 109, 153-160, 2011.05.
231. Keiko Sasaki, Naoyuki Fukumoto, Sayo Moriyama, Tsuyoshi Hirajima, Sorption characteristics of fluoride on to magnesium oxide-rich phases calcined at different temperatures, Journal of Hazardous Materials, 191, 240-248, 2011.04.
232. Moriyasu NONAKA, Tsuyoshi HIRAJIMA and Keiko SASAKI, Upgrading of Low Rank Coal and Woody Biomass Mixture by Hydrothermal Treatment, Fuel, in press, 2011.04.
233. Keiko SASAKI, Hitoshi TAKAMORI, Sayo MORIMAYA, Hitoshi YOSHIZAKA, Tsuyoshi HIRAJIMA, Effect of Saw Dusts on Borate Removal from Groundwater in Bench-scale Simulation of Permeable Reactive Barriers Including Magnesium Oxide, Journal of Hazardous Materials, https://doi.org/10.1016/j.jhazmat.2010.10.067, Vol.185, Issues 2-3, 1440-1447, 2011.01.
234. H.T.B.M. Petrus, Tsuyoshi Hirajima, Yuji Oosako, Moriyasu Nonaka, Keiko Sasaki, Takashi Ando, Performance of dry-separation processes in the recovery of cenospheres from fly ash
and their implementation in a recovery unit, International Journal of Mineral Processing, 98 (2011) 15–23, 2011.01.
235. Anggoro Tri Mursito, Tsuyoshi Hirajima, Keiko Sasaki, Alkaline hydrothermal de-ashing and desulfurization of low quality coal
and its application to hydrogen-rich gas generation, Energy Conversion and Management, 52, 762-769, 2011.01.
236. Himawan Tri Bayu Murti PETRUS, 平島 剛, 笹木 圭子, Effect of pH and Diethyl Dithiophosphate (DTP) Treatment on Chalcopyrite and
Tennantite Surface Observed Using Atomic Force Microscopy (AFM), Colloids and Surface A: Physicochemical and Engineering Aspects, 2011, 9, Vol.389, Issues 1-3, pp.266-273, 2011.01.
237. H. T. B. M. Petrus, T. Hirajima, K. Sasaki, H. Okamoto, Study of Diethyl Dithiophosphate Adsorption on Chalcopyrite and Tennantite at Varied pHs, Journal of Mining Science, 47, 5, 695-702, 2011.01.
238. OSAMA ELJAMAL , KEIKO SASAKI, Shoichi Tsuruyama, TSUYOSHI HIRAJIMA, Kinetic Model of Arsenic Sorption onto Zero-Valent Iron, Water Quality, Exposure and Health, DOI 10.1007/s12403-010-0030-7, in press, 2010.12.
239. Ahmad T. YULIANSYAH, Tsuyoshi HIRAJIMA, Satoshi KUMAGAI, Keiko SASAKI, Production of Solid Biofuel from Agricultural Wastes of the Palm Oil Industry by Hydrothermal Treatment, Waste and Biomass Valorization, in press, 2010.12.
240. Abdul M. HALIM, R. K. MAJUMDER, S. A. NESSA, Y. HIROSHIRO, Keiko SASAKI, B. B. SAHA, A. SAEPULOH, Kenji JINNO, Trace metals in water and sediment from coal mine discharge canal in the Boropukuria, Bangladesh: mobility and environmental significance assessment, J. Hazardous Mater., in press, 2010.07.
241. Keiko SASAKI, Koichiro TAKATSUGI, Tsuyoshi HIRAJIMA, Kenji KANEKO, Toshihiko OHNUKI, , Olli H. TUOVINEN, Characterization of secondary formed As-bearing precipitates in bioleaching of enargite by As-adapted Acidithiobacillus ferrooxidans, Hydrometallurgy, 104, 424-431, 2010., 2010.07.
242. M. A. Halim, R. K. Majumder, S. A. Nessa, K. Oda, Y. Hiroshiro, B. B. Saha, K. Sasaki, K. Jinno, Evaluation of processes controlling the geochemical constituents in deep groundwater in Bangladesh: spatial variability on arsenic and boron enrichment
, Journal of Hazardous Materials, 180, 50-62, 2010.06.
243. Mohsen FARAHAT, Tsuyoshi HIRAJIMA, Keiko SASAKI, Adhesion of Ferroplasma acidiphilum onto Pyrite Calculated from the Extended DLVO Theory using the Van Oss-Good-Chaudhury Approach, Journal of Colloid & Interface Science, 349, 594-601, 2010.06.
244. Tsuyoshi Hirajima, H.T.B.M. Petrus, Yuji Oosako, Moriyasu Nonaka, Keiko Sasaki, Takashi Ando, Recovery of cenospheres from coal fly ash using a dry separation process: Separation estimation and potential application, International Journal of Mineral Processing, 95, 18-24, 2010.06.
245. Anggoro Tri MURSTO, Tsuyoshi HIRAJIAM, Keiko SASAKI, Satoshi KUMAGAI, The effect of hydrothermal dewatering of Pontianak tropical peat on organics in wastewater and gaseous products, Fuel, in press, 2010.06.
246. Keiko SASAKI, Koichiro TAKATSUGI, Kazuhiro ISHIKURA, Tsuyoshi HIRAJIMA, Spectroscopic study on oxidative dissolution of chalcopyrite, enargite and tennantite at different pHs, Hydrometallurgy, 100, 144-151, Vol. 100, pp.144-151, 2010, 2010.01.
247. Pauliina NURMI, Bestamin ÖZKAYA, Keiko SASAKI, Anna H. KAKSONEN, M.-R. Riekkola-VANHANEN, Olli H. TUOVINEN, Jaakko A. PUHAKKA, Biooxidation and Precipitation for Iron and Sulfate Control in Heap Bioleaching Waste Streams, Hydrometallurgy, 101, 7-14, 2010.01.
248. Anggoro T MURSITO, Tsuyoshi HIRAJIMA, Keiko SASAKI, Upgrading and Dewatering of Raw Tropical Peat by Hydrothermal Treatment, Fuel, 89, 635-641, 2010.01.
249. Keiko SASAKI, Takuya KASEYAMA, Tsuyoshi HIRAJIMA, Selective sorption of cobalt over nickel using biogenic manganese oxides, Materials Transactions, Vol. 50, pp.2643-2648, 2009, 2009.11.
250. K. SASAKI, K. TAKATSUGI, T. HIRAJIMA, N. KOZAI, T. OHNUKI, O. H. TUOVINEN, Bioleaching of Enargite by Arsenic-torelant Acidithiobacillus ferrooxidans, Advanced Materials Research, 71-73, 485-488, 2009.10.
251. K. SASAKI, T. KASEYAMA, T. HIRAJIMA, Selective Sorption of Ce3+ over La3+ ion on Biogenic Manganese Oxides, Advanced Materials Research, 71-73, 633-636, 2009.10.
252. Treatment of Heavy Metals in a Constructed Wetland, Kaminokuni, Hokkaido
-Role of Microorganisms in Immobilization of Heavy Metals in Wetland Soils-.
253. Treatment of Heavy Metals in a Constructed Wetland, Kaminokuni, Hokkaido
-Accumulation of Heavy Metals in Emergent Vegetations-.
254. Mohsen Farahat, Tsuyoshi Hirajima, Keiko Sasaki , Katsumi Doi, Adhesion of Escherichia coli onto Quartz, Hematite and Corundum: Extended DLVO Theory and Flotation Behavior, Colloids and Surfaces B: Biointerfaces, Vol. 74, pp.140-149, 2009, 2009.07.
255. Keiko Sasaki, Yousuke Nakamuta, Tsuyoshi Hirajima, Olli H. Tuovinen, Raman characterization of secondary minerals formed during chalcopyrite leaching with Acidithiobacillus ferrooxidans, Hydrometallurgy, Vol. 95, (2009) pp.153-158., 2009.01.
256. K. Sasaki, H. Nakano, W. Wilopo, Y. Miura, T. Hirajima, Sorption and speciation of arsenic by zero-valent iron, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 347, 8-17, 2009, 2008.12.
257. Wahyu Wilopo, Keiko Sasaki, Tsuyoshi Hirajima, Toshiro Yamanaka, Immobilization of Arsenic and Manganese in Contaminated Groundwater by Permeable Reactive Barrier Using Zero Valence Iron and Sheep Manure, Materials Transactions, Vo. 49, No. 10, pp. 2265-2274, 2008.10.
258. W. WILOPO, K. SASAKI, T. HIRAJIMA, Identification of Sulfate- and Arsenate-Reducing Bacteria in Sheep Manure As Permeable Reactive Materials after Arsenic Immobilization in Groundwater., Materials Transactions, Vol. 49, No. 10, pp.2275-2282, 2008.10.
259. Olia V. Karnachuk, Keiko Sasaki, Anna L. Gerasimchuk, Olga Sukhanova, Denis A. Ivasenko, Anna H. Kaksonen, Jaakko A. Puhakka, Olli H.Tuovinen, Precipitation of Cu-sulfides by Copper-tolerant Desulfovibrio Isolates, Geomicrobiology Journal, Vol. 25, pp. 1-8, 2008.07.
260. KEIKO SASAKI, DAVID W. BLOWES, CAROL J. PTACEK, Spectroscopic study of precipitates formed during removal of selenium from mine drainage spiked with selenate using permeable reactive materials, Geochemical Journal, Vol. 42, pp. 283-294, 2008.06.
261. Keiko Sasaki,Shunsuke Nukina,Wahyu Wilopo, Tsuyoshi Hirajima, Removal of arsenate in acid mine drainage by a permeable reactive barrier bearing granulated blast furnace slag: column study, Materials Transactions, Vol. 49(4), pp. 835-844, 2008.04.
262. K. Sasaki, H. Tachibana, Y. Ogawa, H. Konno, Oxidation of Mn(II) Ions in Model and Actual Manganese Drainages by a Fungus Closely Related to Phoma sp. like strain KY-1, Materials Transaction, Vol. 49(4), pp. 845-849, 2008.04.
263. K. Sasaki, D. W. Blowes, C. J. Ptacek, Immobilization of selenate in mine drainage by permeable reactive barriers: column performance., Applied Geochemistry, Vol. 23, No. 5, pp. 1012-1022, 2008.02.
264. K. Sasaki, M. Matsuda, T. Urata, T. Hirajima, H. Konno, Sorption of Co2+ ions on the biogenic Mn deposits by a Mn-oxidizing fungus,Paraconiothyrium sp.-like strain WL-2, Materials Transaction, Vol. 49(3), pp. 605-611, 2008.01.
265. Mohsen Frahat, Tsuyoshi Hirajima, Keiko Sasaki, Yuuki Aiba, Katsumi Doi, Adsorption of SIP E. coli onto quartz and its applications in froth flotation, Minerals Engineering, Vol.21(5), pp.389-395, 2007.12.
266. Jonathan P. Gramp, Jerry M. Bigham, Keiko Sasaki, and Olli H. Tuovinen, Formation of Ni- and Zn-sulfides in cultures of sulfate-reducing bacteria., J. Geomicrobiology, Vol, 24, pp. 2-7, 2007.11.
267. K. Sasaki, M. Matsuda, T. Urata, T. Hirajima, H. Konno, Sorption of Co ions on biogenic Mn oxides produced by a Mn-oxidizing fungus, Paraconiothyrium sp.-like strain., Advanced Materials Research)., 20-21, 607-610, 2007.07.
268. Hidetaka KONNO, Keiko SASAKI, Yuuki OGAWA, Hideki TACHIBANA, Singular effect of carbon fibers on the oxidation of dissolved Mn(II) ions by a fungus closely related to Phoma sp., Materials Transactions, 48(1), 64-67, 2007.01.
269. Jonathan P. Gramp, Keiko SASAKI, Jerry M. Bigham, Olia V. Karnachuk, Olli H. Tuovinen, Formation of covellite (CuS) under biological sulphate-reducing conditions., Geomicrobiology Journal, 23, 613-619, 2006.11.
270. Production of Bio-Coal Fuel from Low Rank Coal and Woody Biomass Mixture by Using a Bench-Scale Continuous Hydrothermal Equipment.
271. Keiko SASAKI, Minoru Matsuda, Tsuyoshi Hirajima, Keishi Takano, Hidetaka Konno, Immobilization of Mn(II) by a Mn-oxidizing fungus Paraconiothryum sp. like strain at neutral pHs., Mater. Trans., 47, 10, 2457-2461, 2006.10.
272. K. Sasaki, T. Sakimoto, M. Endo and H. Konno, FE-SEM study of microbiologically formed jarosites by Acidithiobacillus ferrooxidans., Mater. Trans., 47(4), 1155-1162, 2006.05.
273. Keishi TAKANO, Yasoo ITOH, Tagiru OGINO, Kunihiko KUROSAWA, Keiko SASAKI, Phylogenetic analysis of manganese-oxidizing fungi isolated from manganese-rich aquatic environment in Hokkaido, Japan., Limnology, 2006.01.
274. , [URL].
275. T. Hirajima, A. Bissombolo, K. Sasaki, K. Nakayama, H. Hirai, and M. Tsunekawa, Floatability of rare earth phosphors from waste fluorescent lamps, Intl. J. Miner. Proc., 10.1016/j.minpro.2005.05.002, 77, 4, 187-198, 77, 187-198, 2005.11.
276. T. Hirajima, K. Sasaki, A. Bissombolo, M. Hamada, M. Tsunekawa, Feasibility of an efficient recovery of rare earth-activated phosphors from waste fluorescent lamps through dense-medium centrifugation., Separation and Purification Technology, 10.1016/j.seppur.2004.12.014, 44, 3, 197-204, 44, 197-204, 2005.07.
277. Keiko Sasaki, David Blowes, Carol Ptacek, Spectroscopic study of removal of Se(VI) from mine drainage by areactive permeable barrier column, Groundwater Quality, 2004.07.
278. K. Sasaki, H. Konno, M. Endo, K. Takano, Removal of Mn(II) ions by manganese-oxidizing fungus at neutral pHs in the presence of carbon fiber., Biotechnol. Bioengng., 85(5), 491-496, 2004.06.
279. Activation of manganese-oxidizing fungus with carbon fiber
- Fibrous shape is essential -.
280. K. K. Yoo, K. Sasaki, N. Hiroyoshi, M. Tsunekawa, T. Hirajima, The Effect of Mn2+ concentration on Mn removal by a sulfate-reducing bacteria bioreactor., Mater. Trans., 10.2320/matertrans.45.2429, 45, 7, 2429-2434, 2004.01.
281. K. K. Yoo, K. Sasaki, N. Hiroyoshi, M. Tsunekawa, Fundamental study on the removal of Mn2+ in acid mine drainage using sulfate-reducing bacteria., Mater. Trans., 10.2320/matertrans.45.2422, 45, 7, 2422-+, 2004.01.
282. K. Sasaki, T. Yamashita, M. Tsunekawa, Synthesis of aragonite from calcined scallop shells - Morpholigical characterization by FE-SEM., Shigen-to-Sozai, 118, 553-558, 2002.01.
283. K. Sasaki, M. Endo, K. Kurosawa, and H. Konno, Removal of manganese ions from water by Leptothrix discophora with carbon fiber., Mater. Trans., 43(11), 2773-2777, 2002.01.
284. K. Sasaki, N. Haga, T. Hirajima, K. Kurosawa, M. Tsunekawa, Distribution and transition of heavy metals in mine tailing dumps., Mater. Trans., 43(11), 2778-2783, 2002.01.
285. K. K. Yoo, K. Sasaki, T. Hirajima, M. Tsunekawa, Analysis of heavy metals in a tailing impoundment of abandoned Mn mine by using two sequential extractions., Mater. Trans., 43(12), 3189-3194, 2002.01.
286. K. Sasaki, T. Ogino, Y. Endo, K. Kurosawa, Field study on heavy metal accumulation in the natural wetland receiving acid mine drainage, Mater. Trans., 44(9), 1877-1884, 2003.01.
287. K. Sasaki, T. Ogino, O. Hori, Y. Endo, K. Kurosawa, M. Tsunekawa, Chemical transportation of heavy metals in the constructed wetland impacted by acid drainage., Mater. Trans., 44(2), 305-312, 2003.01.
288. K. Sasaki, H. Konno, Morphological change of jarosite groups formed from biologically and chemically oxidized Fe(III) ions., Can. Mineral., 38, 45-56, 2000.01.
289. K. Sasaki, M. Tsunekawa, S. Tanaka, M. Fukushima and H. Konno, Inhibiting effect of natural organic acids on microbially mediated dissolution of pyrite in acidic environments., Shigen-to-Sozai, 115, 233-239, 1999.01.
290. K. Nakayasu, M. Fukushima, K. Sasaki, S. Tanaka, and H. Nakamura, Comparative studies of the reduction behavior of chromium (VI) by humic substances and their precursors., Environ. Toxicol. Chem., 18, 1085-1090, 1999.01.
291. M. Fukushima, S. Tanaka, K. Nakayasu, K. Sasaki, and K. Tatsumi, Evaluation of copper(II) binding abilities of humic substances by a continuous site-distribution model considering proton competition., Anal. Sci., 15, 185-188, 1999.01.
292. K. Sasaki, M. Tsunekawa, T. Ohtsuka and H. Konno, The role of sulfur-oxidizing bacteria, Thiobacillus thiooxidans, in pyrite weathering., Colloids and Surfaces A: Phisicochemical and Engineering Aspects, 133(3), 269-278, 1998.01.
293. K. Sasaki, O. Tanaike and H. Konno, Distinction of jarosite compounds by Raman spectroscopy., Can. Mineral., 36, 1225-1235, 1998.01.
294. K. Sasaki, Raman study of the microbially mediated dissolution of pyrite by Thiobacillus ferrooxidans., Can. Mineral., 35(4), 999-1008, 1997.01.
295. M. Fukushima, S. Tanaka, K. Nakayasu, K. Sasaki, H. Nakamura and K. Tatsumi, Investigation of copper(II)-binding behavior of fulvic acids by three-dimensional fluorescence spectrometry., Anal. Sci., 13, 1007-1011, 1997.01.
296. K. Sasaki and M. Tsunekawa, Evaluation of tannic and fulvic acids as inhibitors of cell growth, and iron and sulfur oxidation in Thiobacillus ferrooxidans and Thiobacillus thiooxidans., Shigen-to-Sozai (J. Min. Mat. Proc. Inst. Japan), 112, 929-933, 1996.01.
297. K. Sasaki, M. Tsunekawa and H. Konno, Effect of cations on pyrite oxidation with Fe(III) ions near pH 2., Shigen-to-Sozai (J. Min. Mat. Proc. Inst. Japan), 112, 231-237, 1996.01.
298. K. Sasaki, M. Tsunekawa and H. Konno, Effect of Fe(II) ions on pyrite oxidation with Fe(III) ions near pH 2., Shigen-to-Sozai (J. Min. Mat. Proc. Inst. Japan), 112, 49-53, 1996.01.
299. K. Sasaki, M. Tsunekawa, S. Tanaka and H. Konno, Suppression of microbially mediated dissolution of pyrite by originally isolated fulvic acids and related compounds., Colloids and Surfaces A: Physicochemical and Engineering Aspects, 119, 241-253, 1996.01.
300. K. Sasaki, M. Tsunekawa, T. Ohtsuka and H. Konno, Confirmation of sulfur-rich layer formed on pyrite after dissolution by Fe(III) ions around pH 2., Geochim. Cosmochim. Acta, 59, 3155-3158, 1995.01.
301. K. Sasaki, M. Tsunekawa, K. Hasebe and H. Konno, Effect of anionic ligands on the reactivity of pyrite with Fe(III) ions in acid solutions., Colloids and Surfaces A: Physicochemical and Engineering Aspects, 101, 39-49, 1995.01.
302. K. Sasaki, M. Tsunekawa and H. Konno, Characterization of argentojarosite formed from biologically oxidized Fe(III) ions., Can. Mineral., 33(6), 1311-1319, 1995.01.
303. K. Sasaki, H. Konno and M. Inagaki, Structural strain in pyrite evaluated by X-ray powder diffraction., J. Mater. Sci., 29, 1666-1669, 1994.01.
304. K. Sasaki, Effect of grinding on the rate of oxidation of pyrite by oxygen., Geochim. Cosmochim. Acta, 58, 4649-4655, 1994.01.
305. M. Sugawara, K. Sasaki, T. Kambara, Surface-tention titration of calcium(II)and Manganese (II) by using triethanolamine as masking reagent, Fresenius Z. Anal. Chem., 313,237, 1982.12.
Presentations
1. engmeng WANG, Hirofumi AKAMATSU, Keiko SASAKI, Interaction of amino acids with selenate-bearing hydrocalumite as a model of low level radioactive waste, International Symposium on Earth Science and Technology 2020, 2020.11.
2. Li Zhang, Chitiphon Chuaicham, Keiko Sasaki, Electronic structure of ferric doped montmorillonite and its application to photocatalytic reduction of chromate, International Symposium on Earth Science and Technology 2020, 2020.10.
3. Kojo Twum Konadu, Keiko Sasaki,, Challenges to gold recovery from carbonaceous gold ores using biotechnology, 1st International Conference of Asia Pacific Mining and Metallurgy, 2019.11.
4. Kojo T. Konadu, Kwadwo Osseo- Asare, Keiko Sasaki, Challenges to gold recovery from carbonaceous gold ores using biotechnology , African MRS 2019, 2019.12.
5. Takashi Kaneta, Airi Harada, Sumire Kudo, Hiroe Kubota, Keiko Sasaki, Determination of lignin-modifying enzymes by capillary electrophoresis using in-capillary reactions, International Biohydrometallurgy Symposium 2019, 2019.11.
6. Kojo T. Konadu, Ryotaro Sakai, Diego M. M. Flores, Susan T. L. Harrison, Kwadwo Osseo- Asare, Keiko Sasaki, Effect of carbonaceous matter on bioleaching of Cu from carbonaceous chalcopyrite ore, International Biohydrometallurgy Symposium 2019, 2019.10.
7. Keiko Sasaki, Fungally formed Mn oxides and their application to bio-templated Li+ ion sieve, International Biohydrometallurgy Symposium 2019, 2019.10, Manganese oxides are the most reactive adsorbents and oxidants which widely control the cycling of nutrients, metals and carbons as well as the fate of contaminants in environments. Microbial catalysis to oxidize Mn(II) is the primary pathway for the generation of Mn ox-ides in nature. Recent discoveries have identified two important roles of Mn-oxidizing mi-croorganisms for the formation of biogenic Mn oxides: the formation of extracellular su-peroxide (O2-) as an effective oxidant of Mn(II) to Mn(III/IV), and production of organic ligand metabolites to stabilize Mn(III) against its reduction by hydrogen peroxide, which is a reaction product to generate O2-. A Mn-oxidizing fungus, Paraconiothyrium sp. WL-2, which possess high tolerance to Mn(II) as well as great ability to oxidize high concentra-tions of Mn(II), was applied to form the biogenic Mn oxides on the surface of fungal hy-phae as a precursor to an adsorbent for recovery of Li+. Through the solid state reaction, the bio-templated adsorbent of Li+ was synthesized maintaining the tubular shape of fungal hyphae. Biogenic birnessite produced larger fractions of an active constituent as an adsorbent of Li+ than abiotic birnessite, resulting in greater adsorption capacity of Li+ despite its smaller BET specific surface area. Selectivity of Li+ in the presence of 100 times of Na+ concentra-tions, and reusability after acid washing were also evaluated. The application can be realized being based on the several characteristic properties of biogenic Mn oxides: secreted extra-cellular superoxide as an oxidant of Mn(II), secreted metabolites as ligands to Mn(III), for-mation of poorly crystalline birnessite on tubular fungal hyphae as a bio-template, adsorption of Li+ on poorly crystalline birnessite, and easy phase transformation of poorly crystalline birnessite..
8. Keishi Oyama, Kyohei Takamatsu, Hajime Miki, Keiko Sasaki, Naoko Okibe, Carbon-assisted bioleaching of primary copper sulfides, International Biohydrometallurgy Symposium 2019, 2019.10.
9. Kojo T. Konadu, Susan T. L. Harrison, Kwadwo Osseo-Asare, Keiko Sasaki, Bio-mineral processing of double refractory gold ore in sequential treatment using a thermophilic archaeon followed by fungal spent medium, International Biohydrometallurgy Symposium 2019, 2019.10.
10. Quanzhi Tian , Binglin Guo , Shingo Nakama , Li Zhang, Zhaochu Hu, Keiko Sasaki, Suppression of Anionic Pollutant Leaching from Coal Fly Ash by Adding Hydroxylated Calcined Dolomite , Goldschmidt 2019, 2019.08.
11. Binglin Guo, Yihuang Xiong , Weinan Cheng , Sarah Saslow , Ismaila Dabo, Keiko Sasaki , First-Principles Investigations into Iodide and Iodate Incorporation Mechanism into Ettringite, Goldschmidt 2019, 2019.08.
12. Chitiphon Chuaicham, Keiko Sasaki, Energy-resolved distribution of electron traps study for ZnTi mixed metal oxides as photocatalysts to degrade phenol, ACS 2019 Fall, 2019.08.
13. Chitiphon Chuaicham , Keiko Sasaki, Surface Plasmon Resonance Enhanced Visible-Light-Driven Photocatalytic Degradation of Rhodamine B by Sepiolite/C3N4/Pd Nanoparticles Composites, Euroclay2019, 2019.07.
14. Radheshyam R Pawar and Keiko Sasaki, Modulated water-based synthesisof Zr-fumarate MOFs for high-efficiency treatment of selenite and selenate from the aqueous solutions, ACS PACCON 2019, 2019.02.
15. Chitiphon Chuaicham, Keiko Sasaki, Surface Plasmon Resonance Enhanced Visible-Light-Driven Photocatalytic Degradation of Rhodamine B by Sepiolite/Carbon Nitride/Pd Nanoparticles Composites, ACS PACCON 2019, 2019.02.
16. Kancharla Srinivasarao, Keiko Sasaki, Covalently functionalized graphene oxide for the recovery of palladium from spent nuclear fuel, ICEAn 2018, 2018.08.
17. Keiko Sasaki, Binglin Guo, Reduction of selenate in ettringite by calcination, Goldschmidt 2018, 2018.08.
18. Binglin Guo, Keiko Sasaki, Confinement of iodide and iodate in ettringite: the plausible mechanism for various inorganic anions selective incorporation, Goldschmidt 2018, 2018.08.
19. Binglin Guo, Keiko Sasaki, Immobilization of iodine and selenium as radionuclide surrogates in cement related materials , PACCON 2019, 2019.02, The confinement of radionuclides or hazardous elements is an important issue for preventing environmental contamination and helping to maintain safe ecosystems for living organisms. Among the radioactive isotopes, the 129I and 79Se isotope are considered as remarkable environmental risk related to nuclear waste storage and/or disposal because of their relatively long half-life (1.57×107 years and 2.95×105, respectively) and high mobility in soil and aqueous system. Since radioactive isotopes are a relatively emergent contaminant and nuclear wastes are usually immobilized in cement, immobilization of I and Se species to cementitious materials is of great interest. As a major and active component in hydrated cement, ettringite is assumed to play a role in immobilization of toxic anions because of its ion-exchange ability. The present talk will display the immobilization mechanisms and properties of iodine and selenium as radionuclide surrogates in ettringite. In addition, the stability of ettringite after uptake toxic anions is also discussed. After accumulation of radionuclides from a contaminated source, ettringite should be stabilized before landfilling for long time storage. An investigation into developing the alternative method to stabilize hazardous wastes by using industrial byproduct/wastes to synthesis glass-ceramics can be also conducted..
20. Shingo Nakama, Quanzhi Tian, Binglin Guo, Niko Dian Pahlevi, Zhaochu Hu, Keiko Sasaki, Suppression mechanism of anionic pollutants released from fly ash by Ca additives, 米国化学会, 2018.03.
21. Chitiphon Chuaicham, Keiko Sasaki, Effects of precursors on the photocatalytic activities of graphitic carbon nitride in hexavalent chromium reduction and rhodamine B degradation under visible light irradiation, 米国化学会, 2018.03.
22. Kojo Twum Konadu, Keiko Sasaki, Kwadwo Osseo-Asare, Takashi Kaneta, Effect of lignin degrading enzymes on the decomposition of large aromatic hydrocarbons using coronene as a surrogate for powdered activated carbon, International Biohydrometallurgy Symposium, 2017.09.
23. Keiko Sasaki, Yoshikazu Hayashi, Binglin Guo, Immobilization of borate and arsenate from geothermal waters by co-precipitation with hydroxyapatite, Goldschmidt 2017, 2017.08.
24. Wuhui Luo, Sasaki Keiko, Synergistic adsorption of Sr2+ and ClO4− on alginate-encapsulated organo-montmorillonite, Hybrid Materials 2017, 2017.03.
25. Paulmanickam Koilraj, Keiko Sasaki, Multifunctional bio-molecules: A precipitant and anion controlling agent on the synthesis of layered double hydroxides and their arsenate adsorption, Hybrid Materials 2017, 2017.03, Arginine is an important biomolecule, which are widely used as ingredients in food and pharmaceuticals industries [1]. Recently, amino acids are utilized for the synthesis of simple metal oxides and/or metal hydroxides, which showed remarkable electronic and adsorption properties. However, the challenges are the preparation of mixed metal hydroxides or layered double hydroxide (LDHs) using these biomolecules [2]. At present, we have synthesised LDHs using multifunctional amino acids as precipitant and labile anion controlling agent and used for the remediation of aqueous arsenate.
Synthesis of MgAl-LDHs (Mg/Al atomic ratio of 3.0) with controlled labile anion was synthesised by hydrothermal method at 100-150 oC using arginine. Thus prepared materials were utilized for the remediation of aqueous arsenate.
PXRD showed that pure nitrate containing LDHs was obtained at lower temperature due to water hydrolysis. Conversely, at higher temperature LDHs showed carbonate as interlayer anion due to the decomposition amino acid into NH4+ and CO2 which act as precipitant and interlayer anion respectively. Arsenate adsorption studies indicated that the adsorption density is directly related to the amount of labile nitrate present in the interlayer and showed maximum of 1.657 mmol/g for LDH synthesised at 100oC. The mechanism of LDH formation and arsenate adsorption was elucidated by different physicochemical analyses.
In conclusion, for the first time MgAl LDHs with different composition of interlayer anion were synthesised by hydrothermal method using amino acid as precipitant and anion controlling agent without any external base. The products obtained at the end of synthesis are LDH and arginine cation. The LDHs obtained here are used as adsorbent and the arginine cation could be used as chemical intermediates with zero waste disposal promising its superiority..
26. Yuta Kamura, Paulmanickam Koilraj, Keiko Sasaki, Carbon-dot/layered double hydroxide nanocomposite for the co-immobilization of strontium and selenate , CINEST 2016, 2016.12, sStrontium (Sr2+) and anionic sselenate (SeO42-) are the by-products of nuclear reaction. Co-immobilization of these ions are highly desired for total remediation of radioactive waste water. Carbonaceous nanomaterials are received great attention in the field of water remediation and pollution control in recent years. However, the handling of these nanomaterials are very challenging due to increase in the bio-availability and toxicity. At present, Mg2Al-NO3 layered double hydroxides (LDHs) was synthesized and modified using carbon nano-dots. Thus prepared materials were characterized through different physicochemical analyses such as PXRD, FT-IR, Zeta potential and TEM. Strontium and selenate adsorption on Mg2Al-NO3-LDH/C-dot composites showed that the strontium immobilization capacities were increased with increase in the amount of carbon-dot. The mechanism of Sr2+ adsorption on these composites occurs via co-ordination with –COO- group of carbon-dot, while SeO42- occurs through ion-exchange of nitrate present in the interlayer galleries of LDH. These results promising the use carbon-dot/LDH composite materials for the total remediation of both anionic and cationic radioactive nuclides from waste water.

.
27. Sasaki Keiko, Bioleaching of Cu from enargite using thermoacidophilic iron-oxidizing archaeon, Acidianus brierleyi: Spectroscopic study for stabilizing As, Copper 2016, 2016.11.
28. Sasaki Keiko, Wuhui Luo, GRINDING EFFECTS OF MONTMORILLONITE AND ILLITE ON FOLLOWING MODIFICATION BY DIOCTADECYL DIMETHYL AMMONIUM CHLORIDE AND ITS APPLICATION IN PERCHLORATE REMOVAL, Asian Clay 2016, 2016.11.
29. Qianqian Yu, Keiko Sasaki, BIOTEMPLATED SYNTHESIS OF A LITHIUM ION-SIEVE DERIVED FROM BIOGENIC MN OXIDE
, Asian Clay 2016, 2016.11, Microbial oxidation is a primary pathway for the Mn oxides formation in nature. Its unique structural properties provide potential for materials scientists to fabricate new functionalized materials. Using Mn oxidizing fungus Paraconiothyrium sp. WL-2 as a bio-oxidizer as well as a bio-template, a special lithium ion sieve with microtube morphology was prepared by calcination. The poorly crystalline Mn oxide facilitates the formation of well crystalline lithium ion sieve at a relatively lower temperature. The effect of calcination temperature was studied by using in situ X-ray diffraction (XRD), Rietveld analysis, X-ray absorption fine structure (XAFS) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). We found that changes of calcination temperature affected the crystal structure (e.g. contents of the spinel phase), the morphology, as well as the chemical composition (e.g. the average oxidation state of Mn) of the product. And the sorption capacity of lithium ion sieve is related with the content of Mn(III) in spinel phase. The optimized sample shows lithium adsorption capacity which is more than twice higher than particulate materials..
30. Sasaki Keiko, NATURAL ATTENUATION OF ARSENATE-CONTAMINATED RIVER IMPACTED BY ACID MINE DRAINAGES: CHARACTERIZATION OF SUSPENDED PARTICULATE MATTERS , ICHMET 2016, 2016.09.
31. Binglin Guo, Keiko Sasaki, Tsuyoshi Hirajima, COORDINATION CHEMISTRY OF SELENATE IN ETTRINGITE, ICHMET 2016, 2016.09, Introduction
Selenium often occurs in association with sulfide minerals by replacement with sulfur, and its toxicity is known as being associated with a number of specific diseases such as nail abnormalities and changes in peripheral nerves. Selenite (SeO32–) and selenite (SeO42–)are much more mobile and toxic in ecosystems. Furthermore, the high mobility of radionuclide 79Se in aqueous environments can pose the terrible threat because most minerals' surfaces are negatively charged in earth crust and it has a long half life time around 2.95×105 years.
Ettringite, which is one of calcium aluminum hydroxysulfates with several crystal water molecules, often occurs in some alkaline environments like cements. It has a general composition of A6B2(C)3(OH)12•26H2O, where A is Ca2+, Sr2+, Cd2+, Co2+; B is Cr3+, Al3+, Fe3+, Mn4+, Si4+; and C is some anions such as SO42– and SeO42– (Gougar et al., 1996). The unit cell of the crystal consists of columns of {Ca6[Al(OH)6]2・24H2O]}6+ with the inter-column spaces occupied by 3 moles of divalent anions (C) and 2 moles of H2O, which hold columns together through electrostatic force. It has been proved by the bond valence theory that AsO43– is complexed with some functional groups on the surface of columns in ettringite (Myneni et al., 1998). Thus, there are two possibilities in incorporations of oxoanions in ettringite, which are the substitution of intercolumn oxoanions or the coordination of oxoanions with functional group on ettringite. This should affect to the chemical stability of anionic species, which are sometimes pollutants in ettringite.
It is not yet clear whether SeO42– is sorbed through inner-sphere complexation or outer-sphere complexation in ettringite. In other word, the bonding Ca(Al)-O-Se-O3 should be created through covalent bond while the bonding H•••••O-Se-O3 should be formed in the later through electrostatic force. In the present work, ettringite containing different concentrations of selenate was characterized by Fourier Transform infrared spectroscopy (FTIR) and bond valence theory to figure out the sorption mechanism of selenate in ettringite.
Methods
Ettringite was synthesized with the stoichiometric amounts of Ca(OH)2 and Al2(SO4)3 with different concentrations of Na2SeO4 (0.5–20mM) in ultrapure water. All solutions were prepared by deionized water and reagent-grade chemicals. The mixture were covered with parafilm to avoid getting CO2 and stirred using a magnetic stirrer at room temperature for 120 min. Then the pH of supernatant was recorded and suspension was filtered by membrane filter for determination of remaining Ca, Al, Se and S concentrations using inductively coupled plasma optical emission spectrometry(ICP-OES).The precipitates were examined by using scanning electron microscope (SEM), X-ray diffraction (XRD), and FTIR. Bond valence theory(Brown et al.,1985)was also applied to calculate the coordination numbers of O atoms in SeO42–assurface functional groups of ettringite.

Results
Changes of water chemistry during immobilization of SeO42– in ettringite were monitored until the equilibrium by determination using ICP-OES. Based on the results of XRD for the solid residues, there is no other phases than ettringite with increase in SeO42–concentrations. Moreover, SEM image has shown needle-like crystals, which are characteristic to ettringite. These results suggest that immobilized SeO42- were completely substituted into inter column spaces in ettringite structure. Furthermore, as shown XRD results, with increasing the amount of immobilized SeO42-in ettringite, the cell parameters a and c also increased.
In ettringite, there are several types of –OH groups including ≡Ca-OH2, ≡Al-OH and ≡Ca2-OH, which produce board FTIR peaks to assign to the stretching vibration mode of O-H around 3200 to 3560 cm-1. Incorporation of SeO42-into the columns of ettringite perturbed the –OH stretching vibration. With increasing the amount of immobilized SeO42– in ettringite, the intensities of–OH stretching peaks decreased in the range of 3250 to 3400 cm-1 which is assigned to the –OH stretching vibration of ≡Ca-OH2.This indicates that SeO42-interacted with H2O which is coordinated to Ca. Based on the structure of ettringite, ≡Ca-OH2, ≡Al-OH and ≡Ca2-OH sites are arranged in the column surfaces, where≡Ca-OH2 is the most dominant sites. According to the bond valence theory, Se-O has1.62 valence units (v.u.) and O-H does about 0.78 v.u. Ligand exchange to such as ≡Ca-OH-SeO3 does not happen, because Se-O-H bond has been already saturated (Brown et al.,1985). Similar characteristic of AsO43- has been also demonstrated (Myneni et al., 1998). In ettringite, SeO42– can be only interacted with these function groups through the formation of inner-sphere complexes of ≡Ca-O-SeO3. It is supposed that the significant change in –OH vibrations may result from the SeO42– sorption in ettringite and the formation of inner-sphere complexes.
Conclusions
The ettringite shows promising application in immobilization of large concentrations of SeO42– in aqueous environments. In the present work, the mechanism of SeO42– by co-precipitation with ettringite was discussed. According to the FTIR spectra, the peak intensity in –OH stretching mode vibration significantly decreased with increasing the amount of immobilized SeO42– in ettringite. Furthermore, based on the XRD patterns, sorption of SeO42– increased the cell parameters a and c of ettringite. EXAFS and TG-DTA analysis would exemplify this assumption.
.
32. Wuhui Luo, Keiko Sasaki, ADSORPTION CHARACTERISTICS OF HAZARDOUS INORGANIC OXOANIONS ON ORGANOHDPy-MODIFIED -MONTMORILLONITE, ICHMECT 2016, 2016.09, Introduction
Adsorption of individual anions on organo-montmorillonite (OMt) was has been well investigated in previous studies (Bagherifam et al., 2014; Choung et al., 2014). In those studies different amounts of organic modifier with variable structures were usedapplied, resulting in no criterion for comparing the selectivity of anions to OMt. A systematic study in terms of adsorption of six anions on three surfactant-modified bentonites was has been conducted (Behnsen and Riebe, 2008). Their results showed the relationship between affinity and hydration energy of the anions. Besides, the amount of released organic modifier may be associated with the species of target anions. Compared with poorly hydrated anions of smaller size, a fully hydrated anion of larger size would be less able to penetrate into the head group region of a cationic surfactant for effective neutralization of the bilayer (Leontidis et al., 2002). As a result, the original counter ion would be readily replaced with those poorly hydrated anions to form tight binding and to minimize the repulsive force, inhibiting the dissociation of adsorbed surfactant back into the bulk aqueous solution (Li et al., 1997). Thus, to compareit is of great significance to evaluate the adsorption characteristic of inorganic different oxoanions, which include hazardous heavy metals and are often mobile in environments, on OMt is of great significance.
Methods
10 g of Mt with a cation exchange capacity (CEC) of 111.4 meq/100g was dispersed in 500 mL deionized water at room temperature for 2 h. Separately, 44.56 mmol of HDPy-Cl, corresponding to four times the CEC of Mt, was dissolved in 500 mL deionized water. The HDPy-Cl solution was then slowly added into the Mt suspension and the mixture was vigorously stirred for 24 h. The obtained solid was separated by centrifugation, freeze-dried, ground, and sieved.
1.0 mmol/L Na2MoO4, Na2SO4, NaClO4, NaReO4, NaI, KIO3, NaBrO3, NaNO3, Na2SeO3, Na2SeO4, Na2CrO4, Na2WO4, NaVO3, and KH2AsO4 were separately prepared, without pH adjustment. Forty mg HDPy/Mt was dispersed in 50 mL target anion-bearing solution and then shaken at 25 °C for 24 h. The pH and Eh of solutions before and after adsorption were measured. After the mixture was filtered through a 0.45-μm filter, the obtained solution was provided to determine the residual anion concentration in equilibrium using ion chromatography (Dionex ICS-2100, Sunnyvale, CA, USA), and inductively coupled plasma atomic emission spectroscopy (ICP-AES, Seiko Instruments, Chiba, Japan). The amount of released HDPy was determined by UV-vis spectroscopy (UV-2450, Shimadzu, Tokyo, Japan) at 258 nm. The solid was dried and supplied for X-ray diffraction (XRD) measurement to investigate changes in interlayer space.
Results and Discussion
Based on pH and Eh values before and after adsorption, chemical speciation of all anions was not expected to change during adsorption on HDPy/Mt. Among the selected anions, with the exception of IO3, H2AsO4, and CrO42, monovalent anions showed higher adsorption capacities and selectivities on HDPy/Mt than divalent anions. Besides, higher adsorption capacities normally corresponded to the lower amounts of HDPy release as support by the negligible HDPy release after adsorption of monovalent anions. Release of HDPy led to the decrease of interlayer distance as proved by XRD patterns. The released HDPy presented in different forms in solution, which depends on anion species. After adsorption of the anions showing high affinity to HDPy/Mt, HDPy were slightly released in form of HDPy-target anion such as HDPy-NO3, whereas significantly released in form of HDPy-Cl for poorly selective anions which are mainly highly hydrated divalent anions. Hydration of counter ion (Cl) was the driving force of ion exchange, which accounted for the adsorption of inorganic anions on HDPy/Mt. Desorption-adsorption made partial contribution to adsorption of several anions. Dehydration of anions with stronger hydration shells consumed more energy to intercalate into HDPy/Mt and resulted in the decrease of selectivity. Moreover, the increase of dielectric constant of organic-like interlayer phase derived from HDPy release was another key factor influencing adsorption of anions on HDPy/Mt.
Conclusions
Monovalent anions normally showed higher adsorption capacities and selectivities and led to lower HDPy release on HDPy/Mt than divalent anions, because of the higher energy consumption for dehydration of divalent anions. Hydration of counter ion (Cl) was the driving force of anions adsorption on HDPy/Mt. Selectivity of HDPy/Mt to anions depended not only on the change in anionic size in different phases (from r1 in aqueous solution to r2 in the organic solvent-like OMt), but also variation of dielectric constant after HDPy release.
.
33. Binglin Guo, Keiko Sasaki, Removal of selenate by co-precipitate with ettringite in aqueous solution, Goldschmidt 2016, 2016.06, Selenium can be toxicant with high concentrations in aqueous solutions. and 79Se isotope is also one of the radionuclides present in high-level nuclear wastes with long half life periods. Because of negative surface charge of the most minerals in earth crust. S, selenate is quite mobile in ground waters.
Ettringite (Ca6Al2(SO4)3(OH)12•26H2O) is known as one of products formed in an early stage during hydration of Portland cement and can also occur naturally. The structure of ettringite consists consisting of column parts ({consisting of {Ca6[Al(OH)6]2・24H2O]} 6+) and channel parts (including tetrahedral SO42- and H2O). It has been reported that Ca2+, Al3+ and SO42- can be replaced with nuclide species. Selenate can also be partly and fully substituted with sulfate.
In the present work, we have investigated in on immobilization of selenate by co-precipitation with ettringite. , resulting in different types of ettringite by mixing stoichiometric amounts of Ca(OH)2 and Al2(SO4)3, AlCl3 with Na2SeO4 in ultrapure water. Using Ca(OH)2 and AlCl3 as Ca and Al sources, selenate was substituted with sulfate in ettringite, giving providing the highest concentration of Se in the solid residues. The potential stability of selenate-substituted ettringite has been assessed by exposing in aqueous solution under the different pHs. It is was found that more than 90% of selenate was immobilized in the structure of ettringite under the initial pH value from 5 to 11.This suggests that selenate can be effectively immobilized in the structure of ettringite in wide range of pH.
.
34. Keiko Sasaki, Application of iron-oxidizing archeaon to biohydrometallurgy of enargite, Goldschmidt 2016, 2016.06, Microbial oxidation of Fe2+ and reduced sulfur species is a basic reaction to dissolve sulfides in biohydrometallurgy. Although chalcopyrite (CuFeS2) is known as a main Cu resource, arsenic-bearing copper sulfides like enargite (Cu3AsS4) are often accompanied in deep copper ore deposits. To recover Cu even from arsenic-bearing coper sulfides, arsenic immobilization should be considered. Acidianus brierleyi, which is an iron-oxidizing hyperthermophilic archeaon, was applied to bioleaching of enargite at 70˚C in the presence of Fe2+ ions as an energy source in a lab scale to find the optimal condition and elucidate the mechanism under the optimal condition. By controling Fe2+ concentrations and pulp density of enargite, 91% of Cu recovery with immobilizing 94% of arsenic species was concurrently achieved. According to the comprehensive interpretation of XANES As K-edge, XRD, and SEM-EDX, the main storage of arsenic was scorodite (FeAsO4), which is in the most ideal form because of high stability and high density of arsenic. Although the released species from enargite is arsenite and A. brierleyi does not oxidize arsenite into arsenate, arsenic was mainly immobilized as scorodite under the optimized condition. Based on spectroscopic and microscopic observation of not only bulk reaction but also interface reaction involving biological tissues, the reaction mechanism is discussed..
35. Kojo Konadu, Sasaki Keiko, Kwadwo Osseo-Asare, Grace OFORI-SARPONG, Activated carbon as surrogate for carbonaceous matter in gold ores: degradation via enzyme treatment, International Conference of the African Materials Research Society , 2015.12.
36. Shugo NAGATO, Tsuyoshi Hirajima, Sasaki Keiko, Effect of Al3+ Additives on Fluoride Removal by (Co-)Precipitation as Apatites, International Symposium on Earth Science and Technology 2015 (CINEST), 2015.12.
37. Kenta TOSHIYUKI, Tsuyoshi Hirajima, Sasaki Keiko, Co-Precipitation of Boron with Hydroxyapatite Using Various Ca Sources, International Symposium on Earth Science and Technology 2015 (CINEST), 2015.12.
38. Yu TAKAKI, Paulmanickam KOILRAJ, Tsuyoshi Hirajima, Sasaki Keiko, Delaminated Layered Double Hydroxide Nanosheets for Arsenate Immobilization, International Symposium on Earth Science and Technology 2015 (CINEST), 2015.12.
39. Wuhui Luo, Tsuyoshi Hirajima, Sasaki Keiko, Adsorption of Perchlorate on Slurry-like Modified Montmorillonite by Hexadecylpyridinium Chloride, The 6th Asian Conference on Colloid and Interface Science (ACCIS 2015), 2015.11.
40. KOILRAJ PAULMANICKAM, Sasaki Keiko, Amino acid anchored layered double hydroxide nanosheets and their Co2+ cation sorption behavior, The 6th Asian Conference on Colloid and Interface Science (ACCIS 2015), 2015.11.
41. Widi Astuti, Tsuyoshi Hirajima, Sasaki Keiko, Naoko Okibe, Utilization of Metabolic Citric Acid from Aspergillus niger Using Corn Starch in the Nickel Leaching of Indonesian Saprolitic Ore, 19th International Biohydrometallurgy Symposium 2015 (IBS 2015), 2015.10.
42. Sasaki Keiko, (invited) Spectroscopic and microscopic investigation in biohydrometallurgy , International Biohydrometallurgy Symposium 2015 (IBS 2015), 2015.10.
43. Kojo Konadu, Sasaki Keiko, Kwadwo Osseo-Asare, Bio-modification of carbonaceous matters in gold ore: Model experiments using powdered activated charcoal and cell-free extracts of Phanerochaete chrysosporium, 19th International Biohydrometallurgy Symposium 2015, 2015.10.
44. Naoko Okibe, Masahito Tanaka, Sasaki Keiko, Tsuyoshi Hirajima, Effect of Cu(II) on bio-scorodite crystallization using Acidianus brierleyi, International Biohydrometallurgy Symposium 2015, 2015.10.
45. Sasaki Keiko, Spectroscopic and Microscopic Investigation for Biohydrometallurgy, 21st International Biohydrometallurgy Symposium (IBS 2015), 2015.10.
46. Sasaki Keiko, Bio-modification of carbonaceous matters in gold ore: Model experiments using powdered activated charcoal and cell-free extracts of Phanerochaete chrysosporium, 21st International Biohydrometallurgy Symposium (IBS 2015), 2015.10.
47. Yu Takaki, Xinhong Qiu, Tsuyoshi Hirajima, Sasaki Keiko, Removal mechanism of arsenate by hydrocalumite depending on arsenate concentration, EUROCLAY 2015, 2015.07.
48. Wuhui Luo, Sasaki Keiko, Synthesis of surfactant-modified montmorillonites for adsorption of perchlorate, EUROCLAY 2015, 2015.07.
49. Akihiro Inoue, Wuhui Luo, Sasaki Keiko, Sequential Modification of Montmorillonite Using DDAC and BDOAC for Adsorption of Perchlorate, International Symposium Zeolite and Microporous Crystals 2015 (ZMPC 2015), 2015.07.
50. Paulmanickam KOILRAJ, Sasaki Keiko, Fe3O4@MgAl-NO3 Layered Double Hydroxide as Magnetically Separable Phosphate Sorbent From Aqueous Solution, International Symposium on Zeolite and Microporous Crystals 2015(ZMPC2015), 2015.07.
51. Yu TAKAKI, Paulmanickam KOILRAJ, Tsuyoshi Hirajima, Sasaki Keiko, Adsorption Characteristic of Arsenate on Delaminated Layered Double Hydroxides, Euroclay2015, 2015.07.
52. Akihiro INOUE, Wuhui LUO, KWADWO OSSEO-ASARE, Tsuyoshi Hirajima, Sasaki Keiko, Sequential Modification of Montmorillonite Using DDAC and BDOAC for Adsorption of Perchlorate, International Symposium on Zeolite and Microporous Crystals 2015(ZMPC2015), 2015.06.
53. Xinhong Qiu, Sasaki Keiko, Synthesis of layered double hydroxide intercalated with gluconate for removal of boron species, 4th International Conference on Multifunctional Hybride and Nanomaterials (Hybride Materials 2015), 2015.03.
54. Wuhui Luo, Sasaki Keiko, Evaluation of BDTAC, DDAC and BDOAC-modified montmorillonites for perchlorate removal, Hybride Materials 2015, 2015.03.
55. KOILRAJ PAULMANICKAM, Sasaki Keiko, Srinivasan KANNAN, Amino acid assisted solvothermal synthesis of layered double hydroxides, Hybride Materials 2015, 2015.03.
56. Sasaki Keiko, Biohydrometallurgy of enargite: A spectroscopic investigation of bioleaching by thermoacidophilic iron-oxidizing archaeon, Acidianus brierleyi , IGO-2015, 2015.01.
57. Sasaki Keiko, Sequential modification of montmorillonite using DDAC and BDOAC for removal of perchlorate: Effect of DDAC dosage
, CINEST 2014, 2014.12.
58. Shugo NAGATO, Kenta TOSHIYUKI, Takeshi KAWASHIMA, Tsuyoshi Hirajima, Sasaki Keiko, Enhancement in precipitation rate of fluoroapatite by Mg2+ additives: Advanced utilization of hydrate of calcined dolomite in water treatment, International Symposium on Earth Science and Technology 2014 (CINEST), 2014.12.
59. Keiko Sasaki, Qianqain Yu, Synthesis of biogenic Mn oxide and its engineering application to Li ion sieve, 247th American Chemical Society, 2014.03.
Membership in Academic Society
  • Geochemical Society
Awards
  • Silicate Covering Layer on Pyrite Surface in the Presence of Silicon-Catechol Complex for Acid Mine Drainage Prevention
  • Japan Prize Committee Members 2015
  • Characteristic Sorption of H3BO3/B(OH)4- on Magnesium Oxide, , MMIJ Best Paper Award 2015
  • Kyushu University Best Research Activity Award 2013
  • Kyushu University Best Research Activity Award 2012
  • Kyushu University Best Research Activity Award 2011
  • Treatment of Heavy Metals in a Constructed Wetland, Kaminokuni, Hokkaido – Role of Microorganisms in Immobilization of Heavy Metals in Wetland Soils –, MMIJ Best Paper Award 2011
  • Concurrent transformation of Mn2+ and removal of Zn2+ using a Mn-oxidizing fungus Paraconiothyrium sp. WL-2 at pH 6.5、CINEST Best Paper Award 2010
  • Decomposition Behavior of Oil Palm Fiber and Shell under Hydrothermal Treatment, CINEST Best Paper Award 2009
  • Characterization of secondary formed minerals in bioleaching of enargite by As-adapted Acidithiobacillus ferrooxidans, CINEST Best Paper Award 2009
  • Sorption of Co2+ ions on the biogenic Mn deposits by a Mn-oxidizing fungus, Paraconiothyrium sp.-like strain WL-2, Materials Transaction, 49(3), 605-611 (2008), MMIJ Best Paper Award 2008
  • ROLE OF WOOD-CHIPS IN PERMEABLE REACTIVE BARRIERS FOR REMOVAL OF BORATE IN GROUNDWATERS、CINEST Best Paper Award 2008
  • JSPS Bilateral Researcher Exchange Program 2003
  • MMIJ Young Researcher Award 1998
Educational
Other Educational Activities
  • 2020.05.
  • 2019.11.
  • 2019.04.
  • 2019.01.
  • 2018.08.
  • 2018.04.
  • 2017.07.
  • 2012.10.
  • 2009.04.
  • 2008.07.
  • 2008.07.
  • 2008.08.
  • 2007.04.
  • 2007.04.
  • 2006.12.
  • 2006.04.
  • 2005.10.
  • 2005.04.
  • 2004.07.
  • 2004.05.
Social
Professional and Outreach Activities
Investigation of Groundwater Remediation by Permeable Reactive Barriers in North America.