Kyushu University Academic Staff Educational and Research Activities Database
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Keiko Sasaki Last modified date:2018.01.25

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


Graduate School
Undergraduate School
Other Organization
Administration Post
Director of the Green Asia International Leaders Education Center


E-Mail
Homepage
http://process.mine.kyushu-u.ac.jp/index.html
Phone
092-802-3338
Fax
092-802-3338
Academic Degree
PhD. (Eng.)
Field of Specialization
Environmental Remediation, Biomining
Research
Research Interests
  • 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, Qianqian Yu, Manganese oxides in Environments, American Chemical Society Symposium Series, 2014.11.
2. 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. 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, Discharge from accidental nuclear power plants includes boric acid, which is used as a neutron absorbent in nuclear reactors. Co-precipitation of borate with hydroxyapatite (HAp), using Ca(OH)2, is known to be an effectively fast method for stabilization of borate as well as coexisting radioactive nuclides. To reduce bulky volume of solid residues after co-precipitation, calcination is necessary to investigate the chemical stability of targets. Calcination at 850 °C resulted in the high crystalization of HAp with formation of xCaO·B2O3 as a by-phase in which x increased with a decrease in the borate contents. After calcination, the lattice parameter a of HAp showed a reentrant curve and c showed a convex curve with an increase in borate contents. A dissolution assay revealed that calcination sometimes increases the borate moiety and that the acceptable B contents in HAp are lower than 1.59 mmol/g-calcined HAp. These results imply that during calcination of HAp, some borate is excluded to form the by-phase xCaO·B2O3, which is relatively insoluble in water, but some other fractions might be additionally emitted from the amorphous phase to weakly bind the calcined products..
2. 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, 2, 10459-10469, 2018.01, A new one-pot synthesis of highly crystalline MgAl-, CoAl- and
ZnAl-layered double hydroxides (LDHs) containing NO3
@ as
interlayer anion along with the surface functionalization of Larginine
was demonstrated by the ecofriendly alkali-free
arginine-assisted hydrothermal method to examine the adsorptive
reduction of chromate (CrO4
2@) from aqueous solutions.
The amino acid mediated water hydrolysis resulted abundant
OH@ in the medium, which served as precipitant, and the NO3
@
from metal precursor acts as an interlayer anion along with
surface functionalization of amino acid. Adsorption studies
revealed that the removal of CrO4
2@ by anion exchange was the greatest in MgAl-LDH with 1.619 mmol-Cr/g of LDH. The
mechanism of CrO4
2@ removal was due to the ion-exchange of
NO3
@ from the interlayer as well as the counter anions present
on the functionalized arginine cation. The adsorbed CrO4
2@ was
partially reduced to nontoxic Cr3+ on the surface of LDH due to
the presence of amino acid functionalization. The present
technique provides several advantages from the aspect of
sustainable chemistry: (i) avoiding hazardous alkali for the
preparation of LDH, (ii) removal of CrO4
2@ by ion-exchange and
(iii) partial detoxification of CrO4
2@ by reduction to Cr3+ on the
surface of the LDH..
3. Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, Hajime Miki, Keiko Sasaki, Floatability of molybdenite and chalcopyrite in artificial seawater, Minerals Engineering, 115, 117-130, 2018.01, Seawater has been reported to depress the floatability of molybdenum in copper-molybdenum (Cu-Mo) flotation
circuits under alkaline conditions (pH>9.5). However, the seawater used in the process contains various minerals
and flotation reagents, which make it difficult to investigate the depression mechanism. This paper
presents a fundamental study into the effect of artificial seawater as a seawater model solution on the floatability
of molybdenite and chalcopyrite, which are the main minerals in the Cu-Mo flotation process. Floatability tests
in the absence of flotation reagents (i.e., frothers and collectors) reveal that artificial seawater adversely affects
the floatability of molybdenite and chalcopyrite at pH>9. This phenomenon can be attributed to the adsorption
of hydrophilic Mg(OH)2 precipitates formed under alkaline conditions on the mineral surfaces, which increases
the surface wettability of the mineral particles, as shown by contact angle measurements and atomic force
microscopy (AFM) images. The effect of kerosene as a molybdenite collector has also been investigated to assess
its potential in the selective flotation of molybdenite and chalcopyrite in artificial seawater..
4. 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, Seawater has been reported to depress the floatability of molybdenum in copper-molybdenum (Cu-Mo) flotation circuits under alkaline conditions (pH > 9.5). However, the seawater used in the process contains various minerals and flotation reagents, which make it difficult to investigate the depression mechanism. This paper presents a fundamental study into the effect of artificial seawater as a seawater model solution on the floatability of molybdenite and chalcopyrite, which are the main minerals in the Cu-Mo flotation process. Floatability tests in the absence of flotation reagents (i.e., frothers and collectors) reveal that artificial seawater adversely affects the floatability of molybdenite and chalcopyrite at pH > 9. This phenomenon can be attributed to the adsorption of hydrophilic Mg(OH)2 precipitates formed under alkaline conditions on the mineral surfaces, which increases the surface wettability of the mineral particles, as shown by contact angle measurements and atomic force microscopy (AFM) images. The effect of kerosene as a molybdenite collector has also been investigated to assess its potential in the selective flotation of molybdenite and chalcopyrite in artificial seawater..
5. 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, After accumulation of toxic ions from a contaminated source, spent absorbents and coprecipitation sludge should be stabilized before landfilling for long time storage, especially in the case of absorbed radionuclides. Therefore, development of novel and efficient method to stabilize spent absorbents that contain highly toxic ions is urgently needed. In the present work, the use of industrial by-products as raw materials to produce ceramics to treat toxic waste was investigated. As a typical oxoanion absorbent, selenate-doped ettringite was mixed with granulated blast furnace slag and silica fume and then calcined at various temperatures to produce glass-ceramics. Above 800 °C, the amorphous mixture was converted to glass-ceramics, which were subjected to the toxicity characteristic leaching procedure test. The synthesized ceramics exhibited excellent behavior for immobilization of selenate, and only 0.1 mg/L of selenate was leached out. However, the total concentration of selenate in the mixture was not reduced during calcination. The X-ray photoelectron spectroscopy revealed the stabilization mechanism is based on encapsulation. In addition, the ceramic materials exhibited excellent chemical stability at pH 2–12. These results showed that industrial by-products can be successfully applied to produce ceramics for immobilization and storage of hazardous wastes..
6. 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, Co-immobilization of cationic and anionic radionuclides is highly desirable for total remediation of radioactive wastewater. Carbonaceous nanomaterials have received much attention in the field of water remediation and pollution control in recent years. However, the handling of these nanomaterials is challenging due to increased bioavailability and toxicity. In this work, MgAl-NO3 layered double hydroxide (LDH) was synthesized and modified using carbon nanodots (C-dot). The prepared materials were characterized using powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), zeta potential, and transmission electron microscopy (TEM) observation. Adsorption of SeO4 2- and Sr2+ on MgAl-NO3-LDH/C-dot composites showed that the Sr2+ immobilization capacities increased with an increase in the amount of C-dot. The mechanism of Sr2+ adsorption on these composites occurs via coordination with the -COO- group of C-dot, whereas that of SeO4 2- occurs through ion exchange with NO3 - in the interlayer galleries of LDH. The adsorption of Sr2+ and SeO4 2- was enhanced in both bicomponent (Sr2+ + SeO4 2-) and tricomponent systems (Sr2+ + SeO4 2- + M+/M2+ = coexisting cations or An- = coexisting anions) with the presence of other anion and cations. The MgAl-NO3-LDH/C-dot composites demonstrated that the high adsorption efficiency of Sr2+ and SeO4 2- than most of other materials reported. These results demonstrate that MgAl-NO3-LDH/C-dot composites are an effective adsorbent for total remediation of anionic and cationic radioactive nuclides from wastewater..
7. 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, Although the Cs adsorption onto soil minerals has been widely studied, the structural factor of Mn oxides affecting the adsorption behavior of trace amounts of Cs is unclear. In order to elucidate the adsorption mechanisms of radioactive Cs at trace levels and the role of Mn oxides on Cs migration in the terrestrial environment, the Cs adsorption onto birnessite and todorokite was investigated for a wide range of concentrations (1 × 10− 10 mol/L to 0.1 mol/L) and an ion-exchange model was used to interpret the adsorption data. Although birnessite showed a higher Cs adsorption capacity than todorokite, most of the Cs adsorbed onto birnessite was desorbed by ion exchange. Two types of adsorption sites were observed for todorokite. Despite low density, the selectivity coefficient was much higher for the T1 site (LogNa CsKsel = 4.2) than for the T2 site (LogNa CsKsel = − 0.6). Sequential extraction was carried out at Cs concentrations of 1 × 10− 9 mol/L and 1 × 10− 3 mol/L. At lower concentrations, approximately 34% of the adsorbed Cs was residual in the todorokite after the sequential extraction; this value was much higher than the results for the Cs-adsorbed birnessite as well as the Cs-adsorbed todorokite at higher concentrations. The present results indicate that the structural factors of Mn oxides significantly affect the retention capacity of radioactive Cs. Aside from phyllosilicate minerals, todorokite also contributes to the fixation of radioactive Cs in soils..
8. 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, Although ettringite is a crucial material in terms of Se immobilization, the immobilization mechanisms, atomic configuration, and intercolumn structure of Se sorbed in ettringite are unclear. The immobilization mechanism of Se oxoanions was evaluated through structural insight into ettringite. It is contrasting between SeO3 2 − and SeO4 2 − in chemical property of the solid residues after immobilization. The oxoanion exchange with structural SO4 2 − is the main mechanism for immobilization of SeO4 2 −. In contrast, SeO3 2 − is easily immobilized to form inner-sphere complexes in ettringite. In addition, it is necessary to reveal the SeO3 2 − complexation sites for understanding the mechanisms in immobilization of SeO3 2 −. Based on the characterization results with the bond valence theory, the location sites of sorbed SeO3 2 − in ettringite structure were proposed. The results obtained in this work are relevant to the understanding of Se and its isotopes immobilized in cement or alkaline environments, especially for nuclear waste management..
9. Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, Hajime Miki, Sasaki Keiko, Floatability of molybdenite and chalcopyrite in artificial seawater, Minerals Engineering, in press, 2017.09.
10. Wuhui Luo, Takeru Fukumori, Kwadwo Osseo Asare, Sasaki Keiko, Effects of grinding montmorillonite and illite on their modification by dioctadecyl dimethyl ammonium chloride and adsorption of perchlorate, Applied Clay Science, 10.1016/j.clay.2017.06.025, 2017.09.
11. 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, Precipitation of SeO4 2 −-substituted ettringite is an efficient method to immobilize SeO4 2 − under alkaline conditions. The effect of SO4 2 − on SeO4 2 − immobilization was investigated, because SO4 2 − is one of the major ions in aqueous and soil environments and it is easily incorporated in ettringite. We aimed to systemically elucidate the formation mechanisms of SeO4 2 −-substituted ettringite with and without SO4 2 −. When SO4 2 − and SeO4 2 − coexisted, both oxoanions were immediately coprecipitated with ettringite after adding a Ca source. Although SO4 2 − was partially substituted by SeO4 2 − in ettringite, no other phases were formed during the process. Without SO4 2 −, SeO4 2 −-substituted AFm phase was formed as an intermediate, confirmed by X-ray diffraction peak at d 2.878, as well as by scanning electron microscopy with energy dispersive X-ray spectroscopy and zeta potential measurements. It is clear that the incorporation mechanism of SeO4 2 − in ettringite is dependent on coexisting SO4 2 − in aqueous environments..
12. 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, In this study, hexadecyl pyridinium chloride (HDPy-Cl) was applied to modify powdery  and dispersed montmorillonite (P-HDPy/Mt and D-HDPy/Mt), and then perchlorate (ClO4−) andmethyl red (MR) were selected as representatives of hazardous inorganic and organic pollutants to investigate the influence of dispersion of Mt on the adsorption performances using the obtained composites (HDPy/Mt). Based on the patterns of X-ray diffraction and water chemistry results, pre-dispersion of Mt resulted in the lower crystallinity of obtained composite with slightly higher contents of HDPy+, HDPy-Cl and total HDPy with respect to the case of original powdery Mt. Moreover, thermogravimetry results indicated that the amount of HDPy distributed on the external surface on D-HDPy/Mt was greater than that on P-HDPy/Mt, which was inverse for HDPy content in the interlayer space. Two composites showed the similar adsorption capacities for ClO4− and MR but slight difference in adsorption kinetics, resulting from the differences in HDPy contents and configuration. This study would provide constructive references for the applications of organo-Mt in environmental remediation and manufacture of clay/polymer nanocomposites..
13. 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, Although ettringite is a crucial material in terms of Se immobilization, the immobilization mechanisms, atomic
configuration, and intercolumn structure of Se sorbed in ettringite are unclear. The immobilization mechanism of Se
oxoanions was evaluated through structural insight into ettringite. It is contrasting between SeO32– and SeO42– in
chemical property of the solid residues after immobilization. The oxoanion exchange with structural SO42– is the main
mechanism for immobilization of SeO42–. In contrast, SeO32– is easily immobilized to form inner-sphere complexes in
ettringite. In addition, it is necessary to reveal the SeO32– complexation sites for understanding the mechanisms in
immobilization of SeO32–. Based on the characterization results with the bond valence theory, the location sites of
sorbed SeO32– in ettringite structure were proposed. The results obtained in this work are relevant to the
understanding of Se and its isotopes immobilized in cement or alkaline environments, especially for nuclear waste
management..
14. Paulmanickam Koilraj, Yuta Kamura, Sasaki Keiko, Carbon-dot-decorated layered double hydroxide nanocomposites as a multifunctional environmental material for co-immobilization of SeO42- and Sr2+ from aqueous solutions, ACS Sustainable Chemistry & Engineering, 2017.06.
15. Qianqian Yu, Toshihiko Ohnuki, Naofumi Kozai, Fuminori Sakamoto, Kazuya Tanaka, Sasaki Keiko, Quantitative analysis of radiocesium retention onto birnessite and todorokite, Chemical Geology, 2017.06.
16. 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, Exfoliation of layeredmaterials has attracted tremendous interest since nanomaterials have become practically
applied in many disciplines. In this study, the structural transformation of packed columnar selenate ettringite
into nanoscale particles has been investigated. The structural transformation of ettringite has been evidenced
based on the results of X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM),
and extended X-ray adsorption fine structure (EXAFS). The structural transformation is caused by the
electrostatic repulsion between guest sulfate ions and selenate. However, the atomic arrangement of
columnar parts of selenate ettringite is still maintained. In addition, a similar phenomenon is more
noticeably observed when it is soaked in ethanol. This suggests that this columnar material has the
potential to be exfoliated into a single nanoscale column by reactions with polar solvents. Finally, a stable
colloidal solution formed when selenate ettringite was soaked in butanol. This is because the surface of the
columnar parts in ettringite is surrounded by structural water molecules that can interact with OH groups
of strongly polar solvent molecules to form hydrogen bonds that can directly exfoliate selenate ettringite
and convert to nanoparticles. It is clear that ettringite could be directly exfoliated to nanoparticles in polar
organic solvents, which has potential utility for wide applications..
17. 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, Porous carbon composites containing varying La contents were synthesized and studied for the sorption of phosphate. The phosphate sorption capacities increased with increasing La content and showed an almost complete La consumption efficiency (P/La molar ratio of 0.936) for the composite containing a La(OH)3/porous carbon mass ratio of 0.1 (La0.1-PC). Phosphate sorption by these composite materials occurred through precipitation of LaPO4 supported by PXRD, XPS and EDS analyses. Kinetic studies revealed that phosphate sorption by the La0.1-PC composite was rapid and reached equilibrium within 1 h compared to the composites containing higher mass ratio of La(OH)3. The sorption capacity of phosphate was not reduced in the presence 20 mM chloride and 20 mM sulfate, but was disturbed by 20 mM carbonate. The phosphate sorption in the presence of 25 mg/L humic acid was maintained along with the adsorption of dissolved humic acid by electrostatic adsorption onto the carbon support. Interestingly, the phosphate sorption capacity in seawater was twice that in fresh water, likely because the Ca2+ and Mg2+ ions in seawater enhanced the precipitation of phosphate on the surface of La in the La-PC composite. Column experiments verified that the La0.1-PC composite was effective for the continuous treatment of phosphate. The current outcome suggests that the La-PC composite can be used as a multifunctional sorbent for the remediation of phosphate along with alkaline metal ions (Ca2+ and Mg2+) as well as the removal of humic substances in wastewaters. Moreover, the spent sorbent could be repurposed as a phosphate plant fertilizer, where it would reduce the cost of disposal and increase the commercial value..
18. 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, Precipitation of SeO42−-substituted ettringite is an efficient method to immobilize SeO42− under alkaline conditions.
The effect of SO42− on SeO42− immobilization was investigated, because SO42− is one of the major ions in aqueous
and soil environments and it is easily incorporated in ettringite. We aimed to systemically elucidate the formation
mechanisms of SeO42−-substituted ettringite with and without SO42−. When SO42− and SeO42− coexisted, both
oxoanions were immediately coprecipitated with ettringite after adding a Ca source. Although SO42− was partially
substituted by SeO42− in ettringite, no other phases were formed during the process. Without SO42−, SeO42−-
substituted AFm phase was formed as an intermediate, confirmed by X-ray diffraction peak at d 2.878, as well as by
scanning electron microscopy with energy dispersive X-ray spectroscopy and zeta potential measurements. It is clear
that the incorporation mechanism of SeO42− in ettringite is dependent on coexisting SO42− in aqueous environments..
19. 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, After accumulation of toxic ions from a contaminated source, spent absorbents and co-precipitation sludge should be stabilized before landfilling for long time storage, especially in the case of absorbed radionuclides. Therefore, development of novel and efficient method to stabilize spent absorbents that contain highly toxic ions is urgently needed. In the present work, the use of industrial byproducts as raw materials to produce ceramics to treat toxic waste was investigated. As a typical oxoanion absorbent, selenate-doped ettringite was mixed with granulated blast furnace slag (GBFS) and silica fume (SF) and then calcined at various temperatures to produce glass-ceramics. Above 800 °C, the amorphous mixture was converted to glass-ceramics, which were subjected to the toxicity characteristic leaching procedure (TCLP) test. The synthesized ceramics exhibited excellent behavior for immobilization of selenate and only 0.1 mg/L of selenate was leached out. However, the total concentration of selenate in the mixture was not reduced during calcination. The X-ray photoelectron spectroscopy (XPS) revealed the stabilization mechanism is based on encapsulation. In addition, the ceramic materials exhibited excellent chemical stability at pH 2~12. These results showed that industrial byproducts can be successfully applied to produce ceramics for immobilization and storage of hazardous wastes..
20. 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, 520, 146-153, 2017.05, Loy Yang lignite with a high water content was dewatered by freeze drying (FD). The drying kinetics of FD was calculated using thin-layer drying models given in the literature. Residual water content, re-adsorption or desorption behaviors, and pore size distributions of all of the samples were investigated. Furthermore, coating with different amounts of kerosene by direct mixing or adsorption methods to restrain water re-adsorption was also investigated. The results showed that FD dewatering contained three steps: a fast dewatering period (∼2 h), followed by a reduced drying-rate period (2–3 h) and an apparently falling-rate period (>3 h). The Midilli-Kucuk model described the drying process perfectly and could be employed to predict residual water content in the sample at any time during the FD dewatering process. The moisture holding capacity (MHC) of the FD-treated samples was lower than that of raw lignite, which is because of the effect of the water–lignite bond strength and the diffusion adsorption or desorption force. Moreover, adding kerosene by either adsorption or direct-mixing methods can both decrease MHC because kerosene is coated on the surface and in the pores of the lignite. These prevent water re-adsorption. The adsorption method is better than the direct-mixing method because it consumes less kerosene..
21. 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, Amorphous forms of mixed lanthanum-zirconium oxyhydroxide (ZrxLa1-xOOH) composite materials, containing porous sucrose carbon as a dopant (PSC-ZrxLa1-xOOH), were successfully prepared via co-precipitation and characterized by BET surface area analysis, Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). These synthesized materials were utilized for the simultaneous adsorption of AsO33- and F- from a binary mixture solution in batch tests. The ZrxLa1-xOOH and PSC-ZrxLa1-xOOH composite materials showed both fast adsorption rates and high adsorption capacities towards AsO33- and F- in aqueous solution. Most attractively, ZrxLa1-xOOH and PSC-ZrxLa1-xOOH showed better F- adsorption capacity when the pH was lower than 7, better AsO33- removal when the pH was higher than 9 and were superior to previously reported metallic oxide-based sorbents. The mechanism can be interpreted based on the HSAB principle, where the bimetallic oxyhydroxides become “soft acids”, while La3+ and Zr4+ are categorized as “hard acids”. Moreover, the PSC-ZrxLa1-xOOH adsorbent demonstrated high selectivity for AsO33- in the co-existence of other ions in a triple component system. The fast adsorption kinetics and high capacity make the designed PSC-ZrxLa1-xOOH adsorbent a promising advanced material for the removal of AsO33- and F- from water in practical applications..
22. 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.
23. 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, Fourteen anions were selected to investigate their adsorption capacities and affinities to unwashed and washed hexadecyl pyridinium (HDPy)-modified montmorillonite (HDPy/Mt). Correlations between adsorption characteristics and anionic properties including radius and hydration energy were determined. With the exception of IO3 , H2AsO4 , and CrO4 2−, monovalent anions showed higher adsorption capacities and affinities to unwashed or washed HDPy/Mt than divalent anions, because the latter possess higher hydration energies. Unwashed HDPy/Mt demonstrated higher selectivity toward poorly hydrated monovalent anions because it presented a more hydrophobic environment, whereas strongly hydrated divalent anions more readily intercalate into the less hydrophobic washed HDPy/Mt. Hydration of the counter ion (Cl) is the driving force for anion adsorption on HDPy/Mt. Higher energy consumption required to dehydrate divalent anions accounts for their lower affinity. Selectivity of HDPy/Mt to anions depends not only on anion size in different phases (from r1 in aqueous solution to r2 in the organic solvent-like HDPy/Mt), but also the dielectric constant of HDPy/Mt (ε2) after HDPy release..
24. 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, Porous carbon composites containing varying La contents were synthesized and studied for the sorption of phosphate. The phosphate sorption capacities increased with increasing La content and showed an almost complete La consumption efficiency (P/La molar ratio of 0.936) for the composite containing a La(OH)3/porous carbon mass ratio of 0.1 (La0.1-PC). Phosphate sorption by these composite materials occurred through precipitation of LaPO4 supported by PXRD, XPS and EDS analyses. Kinetic studies revealed that phosphate sorption by the La0.1-PC composite was rapid and reached equilibrium within 1 h compared to the composites containing higher mass ratio of La(OH)3. The sorption capacity of phosphate was not reduced in the presence 20 mM chloride and 20 mM sulfate, but was disturbed by 20 mM carbonate. The phosphate sorption in the presence of 25 mg/L humic acid was maintained along with the adsorption of dissolved humic acid by electrostatic adsorption onto the carbon support. Interestingly, the phosphate sorption capacity in seawater was twice that in fresh water, likely because the Ca2+ and Mg2+ ions in seawater enhanced the precipitation of phosphate on the surface of La in the La-PC composite. Column experiments verified that the La0.1-PC composite was effective for the continuous treatment of phosphate. The current outcome suggests that the La-PC composite can be used as a multifunctional sorbent for the remediation of phosphate along with alkaline metal ions (Ca2+ and Mg2+) as well as the removal of humic substances in wastewaters. Moreover, the spent sorbent could be repurposed as a phosphate plant fertilizer, where it would reduce the cost of disposal and increase the commercial value..
25. Sasaki Keiko, Kenta Toshiyuki, Binglin Guo, Tsuyoshi Hirajima, Calcination effect of borate-bearing hydroxyapatite on mobility of borate, J Hazard Mater, 2017.02.
26. 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.
27. 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, Carbonaceous matter in refractory gold ore is known to be one of the primary causes of gold recovery loss.Model
experimentswere conducted to simulate the bio-modification of carbonaceous matter using powdered activated
carbon (PAC) as a surrogate and cell-free spent medium (CFSM) of Phanerochaete chrysosporium. The CFSMwas
used because of the lignin peroxidase and manganese peroxidase secreted by themicrobe during its incubation.
In the present work, an investigation was conducted to determine the physical and chemical alterations in PAC
after enzymatic treatment and its effect on Au(CN)2
− uptake. Characterization of the solid residues of PAC by
13C NMR and N2 adsorption after bio-modification revealed that the treatment had decomposed poly-aromatic
carbons into aliphatic carbons and also reduced the specific surface area from 1430 m2/g to 697 m2/g in
14 days. As a result, Au(CN)2
− uptake decreased from 100% (0.048 mmol/g) to 43% within 12 h primarily due
to the enzyme treatment and adsorption of CFSMcomponents. It further decreased to 26% due to surface passivation
by bio-chemicals derived from CFSM and/or decomposed aliphatic hydrocarbons from aromatic carbons
between 7 days and 14 days. These findings may contribute to efforts to decrease preg-robbing in hydrometallurgical
processing of refractory gold ores..
28. 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, Fourteen anions were selected to investigate their adsorption capacities and affinities to
unwashed and washed hexadecyl pyridinium (HDPy)-modified montmorillonite (HDPy/Mt).
Correlations between adsorption characteristics and anionic properties including radius and
hydration energy were determined. With the exception of IO3-, H2AsO4-, and CrO42-,
monovalent anions showed higher adsorption capacities and affinities to unwashed or washed
HDPy/Mt than divalent anions, because the latter possess higher hydration energies. Unwashed
HDPy/Mt demonstrated higher selectivity toward poorly hydrated monovalent anions because
it presented a more hydrophobic environment, whereas strongly hydrated divalent anions more
readily intercalate into the less hydrophobic washed HDPy/Mt. Hydration of the counter ion
(Cl-) is the driving force for anion adsorption on HDPy/Mt. Higher energy consumption
required to dehydrate divalent anions accounts for their lower affinities. Selectivity of HDPy/Mt
to anions depends not only on anion size in different phases (from r1 in aqueous solution to r2
in the organic solvent-like HDPy/Mt), but also the dielectric constant of HDPy/Mt ( r2) afterHDPy release..
29. 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.
30. 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, Immobilization of fluoride (F−) in apatite using Ca(OH)2 as a mineralizer in the presence of phosphate is known to be
accompanied by a stagnation period. This is caused by the formation of hydroxyapatite and/or fluoroapatite (HAp/FAp)
on the surface of Ca(OH)2, which inhibits the dissolution of Ca(OH)2. Al3+ additives effectively eliminated the delay
period, leading to the rapid formation of apatites by suppressing the formation of CaCO3. Zeta potential measurements
clearly showed that increasing the quantity of Al3+ additives caused not only a decrease in the initial surface charge but
also a decrease in the rate of the surface charge of the solid residues during the reaction, indicating that Al3+ additives enhanced
the formation of HAp/FAp. 27Al-nuclear magnetic resonance (NMR) studies of the solid residues indicated that
the predominant coordination number of Al was always hexagonal ([6]Al) and that the fraction of [6]Al increased with
an increase in the molar ratio of F/Al in the solid residues, suggesting that the stable AlF6
3− complex was easily incorporated
into the apatites. In addition, transmission electron microscope- energy dispersive X-ray spectroscopy (TEM-EDX)
revealed a uniform distribution of Al in the apatites, which suggests that in the initial stages of the reaction, free Al3+ ions
contribute to the formation of apatite crystal seeds independent of Ca(OH)2 particles, resulting in the efficient growth of
apatites containing F−. This result is helpful for the treatment of F−-bearing industrial wastewaters in practical applications
by using an Al-bearing Ca source, such as ground-granulated blast-furnace slag..
31. 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.
32. 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.
33. Sayo Moriyama, Sasaki Keiko, 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 Sci., http://dx.doi.org/10.1016/j.clay.2016.07.016, 132–133, 460–467, 2016.10.
34. 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, tHydroxylated calcined dolomite (HCD) is used as a mineralizer to immobilize borates by co-precipitationwith hydroxyapatite (HAp). HCD sometimes includes appreciable quantities of MgO depending on thedegree of hydroxylation of the calcined dolomite. In this work, the interfacial effects of MgO in HCDon the removal kinetics of borates were examined using Ca(OH)2and HCDs with different degrees ofhydroxylation. As the fraction of MgO phases within the HCD increased, the borate immobilization ratestagnated because the formation of hydroxyapatite (HAp) was inhibited. This effect arose from the inter-action of boric acid (H3BO3) with the MgO in HCD, followed by hydroxylation to cover the Ca(OH)2surfaces with newly formed Mg(OH)2. In the presence of borate, the unstable intermediate [MgB(OH)4]+complex was formed through ligand-promoted dissolution of MgO in the HCD.11B NMR spectra revealedthat the stagnation in immobilization of tetragonal boron ([4]B) species was observed for up to 45 min, accompanied by the suppression of HAp formation. TEM images of the HCD suggested that Ca(OH)2waspartially associated with MgO and Mg(OH)2phases within the HCD and hydroxylation of MgO led to athin covering of the surface of Ca(OH)2with the newly formed gel phases comprising Mg(OH)2/H3BO3that hinders the dissolution of Ca(OH)2. However, when MgO was completely hydroxylated in the HCDthis delay was not observed. This was supported by zeta potential measurements on the solid residuesduring co-precipitation. The results suggest that the degree of hydroxylation of the calcined dolomite inHCD markedly influences the co-precipitation kinetics of borates in industrial water treatment..
35. 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.
36. 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, Nanomaterials have gained much interest in water remediation and pollution control in recent years. However,
the toxicity associated with nanoparticles remaining in solution after remediation has high impact on the environment.
The present study examined the synthesis and characterization of colloidalMg2Al-NO3 layered double
hydroxide (Mg2Al-UD-LDH) nanosheets and their application as adsorbent toward arsenate immobilization. Colloidal
LDH nanosheets featured the absence of nanoparticles release in the environment differently from other
nanomaterials. The adsorption studies conducted in batch method, revealed that colloidal Mg2Al-UD-LDH nanosheets
(obtained by ultrasonic treatment of Mg2Al-NO3-LDH suspension) achieved a higher arsenate adsorption
density of 1.21mmol/g than parentMg2Al-NO3-LDH (1.16mmol/g) at a solid-to-solution dosage of 0.78 g LDH/L.
The adsorption mechanism of arsenate onto colloidalMg2Al-UD-LDH nanosheets proceeded through restacking
of the nanosheets, besides ion-exchange onto Mg2Al-NO3-LDH and surface adsorption onto Mg2Al-CO3-LDH.
Kinetics of arsenate adsorption onto colloidalMg2Al-UD-LDH nanosheetswas rapid, reaching equilibriumwithin
5 min, whereas equilibrium was reached within 120 min in the presence of Mg2Al-NO3-LDH. The colloidal LDH
nanosheets stacking effect was restricted at higher LDH/As ratios owing to electrostatic repulsion among the
nanosheets, as determined by zeta potential measurements. Semi-pilot scale static model systems for arsenate
adsorption were examined to further investigate the adsorption performance of colloidal Mg2Al-UD-LDH
nanosheets in natural water systems such as river, pond, or lake. Arsenate adsorption was rapid onto colloidal
Mg2Al-UD-LDH nanosheets owing to their high dispersibility; specifically, 100% adsorption efficiency was
achieved within 5 min. Thus, the high adsorption capacity, dispersibility, and fast kinetics of arsenate removal
onto colloidal Mg2Al-UD-LDH nanosheets promising for use as an efficient adsorbent for water remediation..
37. Sayo Moriyama, Keiko Sasaki, Effect of freeze drying on characteristics of Mg–Al layered double hydroxides and bimetallic oxide synthesis and implications for fluoride sorption, Applied Clay Science, 132–133 (2016) 460–467, 2016.06.
38. 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, Seawater flotation has been applied to mineral processing in areas located far from fresh water resources.
However, as seawater has a detrimental effect on molybdenite floatability under alkaline conditions
(pH > 9.5), its application in the conventional copper and molybdenum (Cu-Mo) flotation circuit is hindered.
A fundamental study of the effect of two divalent cations in seawater, Mg2+ and Ca2+, on the floatability
of chalcopyrite and molybdenite is presented in this paper. Floatability tests showed that both
MgCl2 and CaCl2 solutions depress the floatability of chalcopyrite and molybdenite at pH values higher
than 9. Furthermore, Mg2+ exerts a stronger effect than Ca2+ owing to the adsorption of Mg(OH)2 precipitates
on the mineral surfaces, as indicated by dynamic force microscopy images. The floatability of chalcopyrite
was significantly depressed compared with that of molybdenite in a 102 M MgCl2 aqueous
solution at pH 11. This phenomenon is likely due to the adsorption of hydrophilic complexes on the mineral
surface, which reduces the surface hydrophobicity. A reversal of the zeta potential of chalcopyrite in
MgCl2 and CaCl2 solutions at pH 11 and 8, respectively, indicated the adsorption of precipitates onto the
surface. In contrast, the zeta potential of molybdenite decreased continuously under the same conditions.
The floatability test of chalcopyrite and molybdenite in mixed systems showed that selective separation
of both minerals should be possible with the addition of emulsified kerosene to a 102 M MgCl2 solution
at pH 11. A mechanism is proposed to explain this phenomenon..
39. 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.
40. 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, We investigated the influence of initial arsenate concentration (C0) in the 5th order of magnitude on removal of
arsenate by hydrocalumite (bimetallic layered double hydroxide, LDH) and Mg-doped hydrocalumite
(trimetallic LDH) fromaqueous solution. These hydrocalumiteswere prepared by the microwave-assisted hydrothermal
treatment. There is a trend that the larger adsorption density of arsenate (Qe) values is observed with
bimetallic LDH under low C0 values and with trimetallic LDH under high C0 values. The transitional C0 values
ranged at 2.10–2.96mM. Comprehensively understanding characterization results for the solid residues after adsorption
of arsenate by X-ray diffraction, 27Al-nuclear magnetic resonance, and scanning electron microscopy–
energy dispersive X-ray, the mechanism to remove arsenate was dependent on arsenate concentrations. At
low arsenate concentration, partial intercalation and dissolution–reprecipitation (DR) happened together.
With increasing C0, full intercalation and DR happened to bring out one phase of arsenate-bearing hydrocalumite.
Under the very high C0, DRmechanism happened at the edge sites of LDH sheets, leading that the newly formed
massive precipitates block the further intercalation with nitrate. As a result, two phases of LDH were observed.
The greater Qewith bimetallic LDH in lowconcentration comes from high crystallinity to enhance partial ion-exchange,
and greater Qe with trimetallic LDH in high concentration is derived from more fragile properties to enhance
DR mechanism..
41. 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, Objective To investigate the bioreduction of toxic
pentavalent vanadium [vanadate; V(V)] in the acidophilic,
Fe(III)-reducing obligately heterotrophic
bacterium, Acidocella aromatica PFBC.
Results Although the initial lag-phase of growth
became extended with increasing initial V(V) concentrations,
the final cell density during aerobic growth of
A. aromatica PFBC was unaffected by up to 2 mM V(V).
While strain PFBC is an aerobe, growth-decoupled PFBC
cell suspensions directly reduced V(V) using fructose,
both micro-aerobically and anaerobically, under highly
acidic (pH 2) and moderately acidic (pH 4.5) conditions.
Bio reduced V(IV) was subsequently precipitated even
under micro-aerobic conditions, mostly by encrusting
the cell surface. An anaerobic condition at pH 4.5
was optimal for forming and maintaining stable V(IV)-
precipitates. Recovery of approx. 70 % of V(V) from the
solution phase was made possible with V(V) at 1 mM.
Conclusions The first case of direct V(V) reducing
ability and its subsequent V recovery from the solution
phase was shown in acidophilic prokaryotes. Possible
utilities of V(V) bioreduction in acidic conditions, are
discussed..
42. 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.
43. 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, The formation of stable bubble–particle aggregates is essential to the froth flotation process. To form
such aggregates, bubbles and particles must collide, the intervening liquid film must be drained below its
critical rupture thickness, and three-phase contact (TPC) formation must occur. A good understanding of
the interaction mechanism between bubbles and particles during collision and attachment is important.
We herein investigated the effects of emulsified kerosene in a 0.01 M MgCl2 solution (a model seawater
component) on bubble interactions with pure molybdenite (MoS2) and chalcopyrite (CuFeS2) surfaces. In
0.01 M MgCl2 at pH 6 and 11, kerosene retarded the bubble surface mobility and reduced the bubble rise
velocity. In the presence of kerosene at pH 6, the TPC formed more rapidly on both mineral surfaces. This
was due to the increase in surface hydrophobicity caused by kerosene. In addition, TPC formation was
more rapid on the molybdenite surface than on the chalcopyrite surface due to the effect of the adsorbed
kerosene and the low surface homogeneity of molybdenite. Finally, floatability tests demonstrated that
the separation of molybdenite and chalcopyrite should be possible by adding emulsified kerosene in a
0.01 M MgCl2 solution at pH 9..
44. 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.
45. 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.
46. 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, Here we describe the application of an in-capillary enzyme assay using micellar electrokinetic chro-matography (MEKC) in the determination of enzyme activity in a crude culture medium containinglignin peroxidase released from Phanerochaete chrysosporium (P. chrysosporium). The method consists ofa plug–plug reaction between lignin peroxidase and its substrate, veratryl alcohol, the separation of theproduct, veratraldehyde, from the other components including the enzyme and the culture medium, andthe determination of the enzyme activity from the peak area of veratraldehyde produced by the plug–plugreaction. This method is more sensitive than conventional spectrophotometry since the background orig-inates from the enzyme and the culture medium can be removed via MEKC separation. Veratraldehydewas separated at −10 kV in a background electrolyte containing 50 mM tartrate buffer (pH 2.5) and50 mM sodium dodecyl sulfate (SDS) after a plug–plug reaction in the capillary for 5 min. The calibrationcurve of veratraldehyde was linear up to 4 pmol (500 M) with a limit to quantification of 0.026 pmol(3.2 M) (SN = 10). The activity of lignin peroxidase was directly measured from the peak area of vera-traldehyde. The activity of lignin peroxidase released from P. chrysosporium into the medium for 7 dayswas successfully determined to be 3.40 UL−1..
47. 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, Needle- and sponge-shaped hydroxyapatite (HAp) particles were synthesized from calcined tuna fish bone
(Tn1000) and commercially available HAp reagent (ChemHAP) by a urea-assisted hydrothermal treatment
using 0.1–1.0Murea solution at 160 °C for 3 h. The Sr2+ sorption capacity of the synthesized HApwas also investigated
using 0–50mMSr2+ solution at 25 °C for 72 h to evaluate its performance as a sorbent for environmental
remediation. Sponge-shaped HAp was formed under hydrothermal conditions with a urea concentration of
1.0 M. With decreasing urea concentration, the morphology of HAp changed from sponge-shaped to needleshaped
crystals, regardless of the starting material. Some calcium carbonate and/or β-tricalcium phosphate impuritieswere
formed fromTn1000 at 0.1–0.5Murea concentration. The Sr2+ sorption mechanismof the synthesized
HAp was estimated using Ca ion-exchange reaction and precipitation of SrCO3. The sponge-shaped HAp
crystals, which had high specific surface area and CO3 2− content, exhibited a large ion-exchange capacity with
Sr2+. In contrast, the ion-exchange ratio of needle-shaped HAp dramatically decreased with increasing initial
Sr concentration. No clear difference in Sr2+ sorption behaviour caused by the choice of HAp synthesis starting
material was observed. These results indicate that the Sr sorption mechanism of HAp is influenced by not only
its composition but also its crystal morphology..
48. 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, The separation of a spent sorbent from treated water after remediation is one of the major difficulties
associated with industrial scale water treatment methods. Fe3O4 particles offer an easy magnetic method
for the separation of used sorbent from water. Due to its low sorption capacity, magnetic Fe3O4 particles
were
first modified with Mg2Al-NO3-LDH prior to use in phosphate remediation. The Fe3O4/Mg2Al-NO3-
LDH composite materials showed a maximum sorption capacity of 33.4 mgP/g while Fe3O4 particles
alone recovered only 4.6 mgP/g. The kinetics of phosphate sorption onto Fe3O4/Mg2Al-NO3-LDH follows
the pseudo-second order kinetic model supported by the best linear regression coefficient value (R2—
1.00). Sorption isotherm studies indicated that it follows the Langmuir monolayer sorption isotherm. The
effect of pH and competing anion studies indicate that this material is highly efficient in a wide pH range
(pH 3–10). Selective sorption of phosphate on Fe3O4/Mg2Al-NO3-LDH was observed in the presence of
excess sulfate, as well as from sea water enriched with phosphate. Fe3O4/Mg2Al-NO3-LDH composite
material offers easy separation of spent sorbents due to magnetic property. The retention of sorption
capacity in a wide pH range, and selectivity in the presence of competing anion, as well as from sea water
suggests that these composite magnetic materials will be effective for wastewater remediation..
49. 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, Co-precipitation of borate in a wide range of concentration with hydroxyapatite (HAp) was investigated
using Ca(OH)2 as a mineralizer in the presence of phosphate. The sorption data of borate was
fitted to
Freundlich model. The maximum sorption density of B/Ca to maintain a mono-phase of HAp was found
around 0.40. In higher B concentrations, borate was still immobilized, however, the crystalization of
hydroxyapatite was inhibited, where the solid residues were accompanied with amorphous CaB2O4, as
well as HAp. Based on 11B-NMR and elemental analysis for solid residues in addition to solution
chemistry, the removal mechanism of high concentration borate can be explained by the surface
complexation of triborate on Ca(OH)2, subsequently decomposition of triborate into monoborate to
release [CaB(OH)4]+ and B(OH)4
, followed by co-precipitation with HAp. These tetragonal B species were
immobilized in the solid residues including amorphous HAp. During the process there was a trend to
eliminate carbonate from the solid phase. TEM images suggested that the HAp particles precipitated at
room temperatures were in a
fibrous shape consisting of a number of short rods when borate species are
not added. When borate species were immobilized, the HAp particles have gotten swelled with losing
fibrous shapes. When further higher borate concentrations were encapsulated in co-precipitated
products, the morphologies were dramatically changed, that is, nano-sized and less crystalline HAp
particles were enveloped by possibly amorphous CaB2O4..
50. 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, A novel method is reported for surfactant modification of montmorillonite (Mt), and then the performance
of the surfactant-modified Mt was investigated for the removal of perchlorate (ClO4). Mt was first
modified with dimethyl dioctadecyl ammonium chloride (DDAC) under microwave irradiation, which
was followed by a second modification with benzyl octadecyl dimethyl ammonium chloride (BODAC).
The influence of the added amount of DDAC in terms of ClO4 adsorption to the modified Mt was
intensively investigated. In addition, sequential and simultaneous-mixing methods were compared for
preparation of the modified Mt in terms of ClO4 removal performance. Using sequential modification,
addition of DDAC corresponding to 0.05 times the cation exchange capacity of Mt significantly increased
BODAC uptake, resulting in the highest adsorption capacity for ClO4 (1.08 mmol/g). This can be explained
by the good balance between the decrease of steric hindrance and the formation of a hydrophobic
interface because of adsorbed DDAC. In contrast, for a composite synthesized with the same ratio of
DDAC to BODAC, the simultaneous-mixing method resulted in modified Mt with much poorer ClO4
removal performance than the sequential modification method because of the negligible contribution of
DDAC to BODAC uptake by Mt. Moreover, a high binding affinity of ClO4 to the sequentially modified
composite was obtained because of hydrophobicity of interlaced alkyl chains..
51. 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.
52. Mari Yoshida, KOILRAJ PAULMANICKAM, Xinhong Qiu, Tsuyoshi Hirajima, Sasaki Keiko, Sorption of arsenate on MgAl and MgFe layered double hydroxides derived from calcined dolomite, J. Environ. Chem. Engng., 10.1016/j.jece.2015.05.016, 3, 1614-1621, 2015.10.
53. 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, Hydroxylated calcined dolomite (HCD) is practically used as a mineralizer to immobilize fluoride by co-precipitation with hydroxyapatite (HAp) and precipitation as fluoroapatite (FAp). It has an advantage to remove fluoride without stagnation, which is always observed with Ca(OH)2 alone. HCD includes a certain content of MgO and Mg(OH)2 as well as Ca(OH)2. In the present work, the mechanism to explain the enhancing role of Mg components on removal kinetics of fluoride was aimed to elucidate. Nano-domain observation approaches were conducted by TEM when Ca(OH)2 is added as a Ca source in the presence of different Mg2+ concentrations, instead of HCD. With increase in Mg2+ concentrations in the presence of Ca(OH)2, removal rate of fluoride was enhanced. The enhancement was also observed with HCD. Mg2+ and [Mg(OH)] +species, which can be derived from HCD, are adhered to the negatively charged c-plane of freshly formed amorphous HAp/FAp and CaCO3. As a result, the surface of Ca(OH)2 particles are gotten rid of hetero-coagulation with HAp/FAp and CaCO3 in the presence of Mg2+ and [Mg(OH)]+ species, and maintained to release Ca2+ and OH- ions, facilitating to precipitate HAp and FAp for immobilization of fluoride. Without Mg2+ additives the Ca(OH)2 surfaces are blocked by insoluble HAp/FAp through hetero-coagulation. This interpretation is also supported by TEM observation, which is well consistent with XRD results. The findings indicate that MgO and Mg(OH)2 contents in HCD influence the removal kinetics of fluoride by (co-)precipitation as apatites in industrial water treatment. Understanding the surface science in nano-domain is important in parallel reactions of dissolution and precipitation..
54. 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.
55. 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.
56. 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.
57. 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, Mg–Al bimetallic oxides produced via the calcination of hydrotalcite-like compounds
([(Mg0.75Al0.25(OH)2](An)0.75/nmH2O, where A is an anionic species) exhibited high potential for the
removal of boron from aqueous solutions. X-ray diffraction patterns for the produced bimetallic oxides
revealed that MgO was the primary phase within the range of investigated calcination temperatures.
In addition, 11B NMR spectral analyses indicated that the Mg–Al bimetallic oxides captured trigonal B
([3]B) and tetrahedral B ([4]B) after the sorption of boron, regenerating hydrotalcite-like compounds. As
the initial concentration of boron increased, the percentage of tetrahedral [4]B in solid residues after
the sorption of boron increased. The [4]B/[3]B ratios in the solid residues increased with time along with
the regeneration of hydrotalcite-like compounds. Furthermore, the Mg–Al bimetallic oxides produced
from hydrotalcite-like compounds were more favorable than other bimetallic oxides and effective than
single-phase MgO produced from MgCO3 at the same temperature, indicating that Mg–Al bimetallic oxides
are stable materials with the potential for use in the remediation of contaminated sites and water..
58. 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, A series of organo-montmorillonites (organo-Mt) was synthesized using various cationic surfactants with different
alkyl-chain lengths, head groups, and alkyl-chain numbers, whichwere systematically examined for perchlorate adsorption.
The products were characterized by the specific surface area, field-emission scanning electron microscopy,
X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. In addition, the
surfactant loadings and surface charges were investigated by CHN analysis and zeta potential measurements. The
greatest adsorption capacity of 0.95 mmol/g-composite was obtained on benzyloctadecyldimethylammoniummodified
Mt. Increasing the alkyl-chain length significantly enhanced the capacity and selectivity for perchlorate
adsorption, but resulted in decrease of adsorption rate. Compared with trimethylammonium and pyridinium with
the same alkyl-chain length, the benzyldimethylammonium as a head group showed better performance in terms
of adsorption capacity and selectivity of perchlorate because of higher hydrophobicity. Moreover, increasing the
alkyl-chain number decreased adsorption rate, but enhanced adsorption capacity, because of dense packing of
alkyl chains and high driving force for entrapment of counter ion-accompanying surfactant. The perchlorate adsorption
performance of organo-Mt was synergistically influenced by the alkyl-chain length, head group and alkyl-chain
number of the surfactants used for modification..
59. Moriyasu Nonaka, Tsuyoshi Hirajima, Keiko Sasaki, Hydrothermal treatment of lignite for CO2 gasification, J MMIJ, 131, 5, 219-225, 2015.05.
60. 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.
61. 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, Hydrocalumite (Ca-Al-layered double hydroxide (LDH)) was prepared and applied for the
removal of borate. The properties of Ca-Al-LDH calcined at different temperatures were diverse, which
affected the sorption mechanism of boron species. The lowest sorption density of boron was observed
for uncalcined Ca-Al-LDH. The fastest sorption rate was observed for Ca-Al-LDH calcined at 900 °C (Ca-
Al-LDH-900), while the highest sorption density within 48 h was observed for Ca-Al-LDH calcined at
500 °C. The solid residues after sorption were characterized by 11B-NMR, 27Al-NMR, SEM, and XRD to
investigate the sorption mechanism. Dissolution-reprecipitation was the main mechanism for sorption
of borate in Ca-Al-LDH. For Ca-Al-LDH calcined at 300 and 500 °C, regeneration occurred in a short
time and the newly forming LDHs were decomposed to release Ca2+ ions and formed ettringite with
borate. Two stages occurred in the sorption of boron by Ca-Al-LDH calcined at 900 °C. In the first stage,
boron species adsorbed on the alumina gel resulting from the hydration of calcined products. In this
stage, borate was included as an interlayer anion into the newly forming LDHs in the following stage,
and then immobilized as HBO32− into the interlayer, most the LDHs..
62. 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.
63. 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.
64. Moriyasu NONAKA, Tsuyoshi HIRAJIMA, Satoshi KUMAGAI,Keiko SASAKI, Hydrothermal Treatment of Lignite for CO2 Gasification, Journal of MMIJ, Vol.131, No.5, pp. 219-225, 2015.03.
65. 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.
66. 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.
67. 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.
68. 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.
69. 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, Adsorption of Cs+ on biogenic birnessite was investigated and compared with (ad)sorption of other heavy metals and also with (ad)sorption on chemically synthesized birnessite. The adsorption density of Cs+ on biogenic birnessite was smaller than that on chemically synthesized birnessite; however, the (ad)sorption densities of Co2+ and Ni2+ on biogenic birnessite were larger than on chemically synthesized birnessite. These phenomena can be interpreted by considering the distinctive nano-structure of biogenic birnessite, which is not only poorly crystalline and includes organic matter but also according to EXAFS contains a greater proportion of vacant central metals sites than is found in synthetic birnessite. Adsorbed Cs+ ions on both birnessites were mainly in the form of outer sphere complexes, which cannot easily occupy vacant central metal sites in biogenic birnessite. Biogenic birnessite has a greater specific surface area and more fine pores than synthetic birnessite, but these factors do not necessarily lead to more adsorption sites for Cs+ ions. .
70. 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.
71. 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, Microbial catalysis, a primary pathway for the generation of Mn oxides in most natural environments, provides potential to fabricate new materials. A microtube-type lithium manganese oxide (LMO-MT) was synthesized through solid-state transformation using Mn-oxidizing fungus, Paraconiothyrium sp. WL-2. Compared with abiotic precursors, the lithium-ion sieve microtube (HMO-MT) showed better performance for Li+ recovery. In order to clarify the formation process of LMO-MTs, in situ high-temperature X-ray diffraction was used to compare with three synthetic references. The effects of calcination temperature on crystal phase, composition, particle size and lattice parameters of the LMO-MTs were systematically discussed. It was found that the poorly crystalline structure of biogenic precursor as well as high content of organic matter facilitated the formation of highly crystalline LMO-MTs at low temperature. The unique structural properties of LMO-MTs, including high crystallinity and small lattice constant, are attributed to the high Li+ sorption capacity of HMO-MTs.

.
72. 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, Hydroxyapatite (HAp) which has ion-exchange properties is a useful sorbent for heavy metals and radionuclides. Ion-exchange capacity is influenced by the composition and crystallinity of HAp. In this study, synthesis of HAp from calcined fish bones was investigated, focusing on the effects of major trace elements. The HAp formed by calcination of fish bones is most likely B-type carbonated HAp. Even when we include the Na, K and Mg contents, the molar ratio of (Ca+substituted cation)/P of fish bones was about ~5% lower than the theoretical one (Ca/P=1.67). X-ray diffraction and EXAFS analysis results indicated that the crystallinity of Horse mackerel bones (Hm) is the lowest. Calcined Hm had the highest Mg content, accompanied with the formation of β-tricalcium phosphate and the least crystalline HAp of the fish bones studied. In calcination of Tuna bones (Tn), which had a high Ca/P ratio and low Mg content, highly crystalline HAp and calcium oxide were formed at temperatures above 800 °C. The findings are useful for application of calcined fish bones as green materials for water remediation, because these factors strongly affect the efficiency of ion exchange in HAp and the pH changes in solutions after HAp immersion..
73. 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.
74. 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, The thermoacidophiliciron-oxidizingarchaeon Acidianus brierleyi is amicroorganismthatcouldbe
useful intheremovalofinorganicAsfromwastewater,becauseitsimultaneouslyoxidizesAs(III)and
Fe(II) toAs(V)andFe(III)inanacidicculturemedium,resultingintheimmobilizationofAs(V)asFeAsO4.
Toinvestigatetheoxidationmechanism,speciationoftheAsspeciesinboththecellsanditsculture
media isanimportantissue.HerewedescribethesuccessivedeterminationofAs(III),As(V),andtotalAs
in A.brierleyi and itsculturemediumviaafacilemethodbasedoninductivelycoupledplasma–optical
emission spectroscopy(ICP–OES) witha flow injectionpretreatmentsystemusingamini-columnpacked
with ananion-exchangeresin.The flow-injectionpretreatmentsystemconsistedofasyringepump,a
selection valve,andaswitchingvalve,whichwerecontrolledbyapersonalcomputer.Samplesolutions
with thepHadjustedto5were flowedintothemini-columntoretaintheanionicAs(V),whereasAs(III)
wasintroducedintoICP–OES withnoadsorptiononthemini-columnduetoitselectricallyneutralform.
An acidicsolution(1MHNO3) wasthen flowedintothemini-columntoeluteAs(V)followedbyICP–OES
measurement. ThesamesamplewasalsosubjectedtoICP–OES withoutbeingpassedthroughthemini-
column inordertodeterminethetotalamountsofAs(III)andAs(V).Themethodwasverified by
comparing theresultsofthetotalAswiththesumofAs(III)andAs(V).Thecalibrationcurvesshowed
good linearitywithlimitsofdetectionof158,86,and211ppbforAs(III),As(V),andtotalAs,respectively.
The methodwassuccessfullyapplicabletothedeterminationoftheAsspeciescontainedinthepelletsof
A.brierleyi and theirculturemedia.TheresultssuggestedthattheoxidationofAs(III)wasinfluenced by
the presenceofFe(II)intheculturemedium,i.e.,Fe(II)enhancedtheoxidationofAs(III)in A.brierleyi. In
addition, wefoundthatnosolubleAsspecieswascontainedinthecellpelletsandmorethan60%ofthe
As(III) intheculturemediumwasoxidizedby A.brierleyi aftera6-dayincubation..
75. 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.
76. 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.
77. 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.
78. 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, Permeable reactive barrier (PRB) column tests for removal of borate were carried out over 287 days corresponding to 76 pore volumes (pv), using MgO agglomerates as the primary reactive material, with and without boron-specific resin (CRB05). Adding 3 (% v/v) CRB05 increased the column shelf life (the time until effluent contains the maximum boron concentration for drinking water) by about 50%, and increased boron accumulation within the column by 15% over 76 pv. The quantities of boron captured were 15–17 mg/g-CRB05, and 1–2 mg-B/g-MgO, decreasing with increasing distance along the column. Rietveld refinement of X-ray diffraction patterns from solid residues after 76 pv revealed that 69–78% of the MgO was transformed into Mg(OH)2 independent of distance along the column, implying that hydration of MgO is not always associated with integration of borate. 11B-NMR spectra demonstrated that trigonal B ([3]B) is predominantly immobilized in Mg(OH)2 in both columns, while tetragonal B ([4]B) is largely trapped in the added CRB05. The complexed forms of [4]B with the N-methylglucamine group after 76 pv were mostly bischelate, with some monodentate. CRB05 contributed to immobilization of [4]B (which is difficult to react with MgO), however, the resin surface was gradually covered with Mg(OH)2 and inactivated..
79. 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, The drawbacks of using layered double hydroxides (LDH) for borate removal were influenced by other anions and difficulties in separation from the waterwaters. In this research, a novel composite filter papers, in which filter paper serves as the substrate to immobilize the LDH on the surface (F-LDH-CO3) as an adsorbent for borate removal was synthesized by an in situ hydrothermal crystallization method. Based on this new composite, chloride (F-LDH-Cl) and gluconate (F-LDH-G) have been intercalated into the interlayer of LDH grown on the surface of filter paper. The influences of the molar ratio of gluconate/LDH and reaction time on the synthesis of F-LDH-G have been explored. PResults products are were characteristized by X-ray diffraction (XRD) and scanning electron microscope microscopic observation (SEM), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (13C-NMR) as well as evaluated as adsorbent to removesorption densities of borate. The results showed that LDH with the interlayer of carbonate was immobilized on the fiber of filter paper after hydrothermal treatment, and chlorine chloride and gluconate were also successfully intercalated into the interlayer of LDH. The optimum molar ratio of gluconate/LDH and reaction time in this research for prepared F-LDH-G from F-LDH-Cl are 40 and 24 h (F-LDH-G-40-24h). Compared the sorption ability of different materials, F-LDH-G-40-24h had a higher adsorption capacity and stability than the original filter paper and filter paper contained other LDH, even in the presence ofwhen the solutions contained other anions. According to the results of 11B-NMR, forming formation of complex with borate as bischelate and monodentate types was the main mechanism of borate removal by LDH with gluconate on the surface of filter paper..
80. 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, Magnesia (MgO), which can be obtained by calcination of natural magnesite, is one of the most effective known sorbents for borate in aqueous solutions. Here we examine the effect of calcination temperature on sorption of borate for MgO-rich phases produced by calcination of magnesite at 873–1373 K. Calcination at or above 1273 K produced a single magnesium oxide phase, whereas basic magnesium carbonates (mMgCO3·nMg(OH)2·xH2O) formed in association with magnesium oxide at or below 1073 K. Calcination temperature directly affected the efficiency of decarbonation of magnesium carbonate, and the solubility and basicity of magnesium oxide in the resultant calcined products. These factors (along with the boron concentration) essentially control the immobilization mechanism of borate on the calcined MgO-rich phases. After sorption of borate on products calcined at lower temperatures, different types of basic magnesium carbonates were formed that are less effective at immobilizing borate. At low borate concentrations, under saturation for magnesium borate hydrate (Mg7B4O13·7H2O), co-precipitation of borate with Mg(OH)2 predominates. However, as magnesium borate hydrate becomes supersaturated, both precipitation of Mg7B4O13·7H2O and co-precipitation with Mg(OH)2 contribute significantly to borate immobilization. Calcination temperature is a key practical factor affecting the borate sorption efficiency by changing the immobilization mechanism..
81. 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, Trace metals were analyzed in water and sediment
samples from Barapukuria coal mine area of Bangladesh in
order to evaluate their mobility and possible environment
consequences. Cadmium is the most mobile element with an
average partition coefficient (log Kd) of 2.95 L/kg, while V is
the least mobile element with a mean log Kd of 5.50 L/kg, and
their order of increasing mobility is: V < As < Pb < Fe < Cr <
Se < Mn < Ni < Zn < Cu < Ba < Sr < Cd. Contents of organic
carbon in sediment samples shows strong positive correlations
with most trace metals as revealed by the multivariate geostatistical
analysis. The overall variation in concentration is
mainly attributed to the discharge of effluents originating from
the coal mining activities around the study area. Compared to
their background, Ni and Cu are the most enriched while
significant enrichment of As, Mn, Ba, Sr, Cr, and Pb is also
observed in the sediments. Geoaccumulation indices (Igeo)
suggest sediments are moderately to heavily polluted with
respect to Ni and Cu. The metal pollution index (MPI) varied
from 91.91 to 212.01 and the highest value is found at site
CM03 that is close to discharge point. The sediment quality
guideline index (SQG-IIntervention) values (0.56–1.52) suggest
that the sediments at the study area have moderate to high
ecotoxicological risk..
82. 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, Microbial transformations, a primary pathway for the Mn oxides formation in
nature, provide potential for material-oriented researchers to fabricate new 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
through a solid-state transformation. Varying the calcination temperature from 300 to
700°C was found to influence sample properties and consequently, the adsorption of Li+.
Lithium manganese oxide microtube (LMO-MTs) calcined at different temperatures as
well as their delithiated products (HMO-MTs) were characterized by X-ray diffraction
(XRD), X-ray absorption fine structure (XAFS) spectroscopy, scanning electron
microscopy (SEM), and transmission electron microscopy (TEM). Calcination
temperatures affect not only the content but also the crystal structure of LMO spinel,
which is important in Li+ adsorption. The optimized sample was obtained after
calcination at 500°C for four hours, which shows higher Li+ adsorption capacity than
particulate materials..
83. 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, Natural dolomite was calcined at different temperatures in the range 873–1373 K and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption/desorption isotherm. The calcination temperature had considerable effect on the surface chemical composition, crystallinity, and basicity of CO2 gas sorption of each component in the calcined products. The sorption isotherm of both in low and high concentrations of fluoride (F–) was investigated for selected calcination products. The sample calcined at 973 K was found to show the highest sorption density for F– at equilibrium concentrations lower than 0.5 mM, which was equivalent to the maximum concentration limit of F–. In this range, the principle of F– removal is mainly based on destructive hydration of MgO. At equilibrium concentrations of F– higher than 0.5 mM, the sorption process was controlled by precipitation of CaF2 and co-precipitation with Ca(OH)2 due to excess liberation of Ca2+ ions from CaO. In this concentration region the products of calcination at higher temperatures are profitable for the immobilization of F–. Additionally, the effect of CO2 gas derived from carbonates on the reactivity of MgO to remove F– during calcination of natural dolomite was also discussed..
84. 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, There has been an increasing interest in the application of Mn(II) oxidizing microbes
for Mn(II) containing waste water treatment, as well as biogenic Mn oxides for remediation of
a number of toxic metals. Sambe hot spring in Shimane Prefecture, Japan is known for its
Mn-rich spring water, and Mn oxide sediments are widely distributed over an area of 60 m ×
80 m of this region. With an aim to find out Mn(II) oxidizing microorganisms responsible for
this massive Mn(II) oxide deposit formation, culture enrichment was undertaken.
Pseudomonas sp. strain MM1 was isolated as dominant Mn(II) oxidizing bacterium from the
site. Biogenic Mn oxide formed by strain MM1 was shown to be poorly-crystalline birnessite,
having the large specific surface area of 90 m2·g-1. Mn(II) was readily oxidized by strain
MM1 during the stationary phase and initial Mn(II) concentrations of up to 1.0 mmol·dm-3 (55
mg·dm-3) went well below the effluent standard of dissolved manganese (10 mg·dm-3; set by
Japanese Ministry of Environment). Strain MM1 grew heterotrophically and Mn(II) did not
serve as the sole electron donor. Nano-sized (30-50 nm) Mn oxide particles were produced by
strain MM1, which later chained or aggregated to form larger Mn oxide minerals. Cells were
observed eventually encrusted inside the Mn oxides. This study showed the important role of
strain MM1 in the production of massive Mn oxide deposits at Sambe hot spring. The Mn(II)
oxidizing ability of this strain is potentially applied for bioremediation of toxic metals..
85. 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, Oxidation of Co by Mn oxide has been investigated using abiotically synthesized Mn oxide. However, oxidation of Co by biogenic Mn oxide is not well known. In this study, we isolated a Mn-oxidizing bacterium (Pseudomonas sp.), designated as strain NGY-1, from stream water. Sorption experiments on Co were carried out using biogenic Mn oxide produced by strain NGY-1. Similar sorption experiments were also conducted using a synthetic analogue of δ-MnO2. Sorption of Co on δ-MnO2 was faster and stronger than that on biogenic Mn oxide, which was possibly due to their structural difference and/or the presence of bacterial cells in biogenic Mn oxide. X-ray absorption near-edge structure spectra clearly demonstrated that Co was oxidized from the divalent to the trivalent state on biogenic Mn and δ-MnO2. The oxidation property of both the biogenic Mn oxide and δ-MnO2 was stronger under circumneutral conditions than under acidic conditions. Linear combination fitting using divalent and trivalent Co reference materials suggested that ~ 90% of Co was oxidized at pH ~ 6, whereas ~ 80% was oxidized at pH ~ 3. Oxidation properties of the biogenic Mn oxide and δ-MnO2 were similar, but Co(II) oxidation by biogenic Mn oxide was slower than that by δ-MnO2. The difference of Co oxidation may be caused by the coexisting bacterial cells or structural differences in the Mn oxides..
86. 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, The reaction mechanism of H3BO3/B(OH)4– with MgO in aqueous phase was investigated using sorption isotherm, XRD, 11B-NMR, and FTIR. Release of Mg2+ was observed soon after contact of MgO with H3BO3 and maximum released Mg2+ was proportional to the initial boron concentration, suggesting ligand-promoted dissolution of MgO by H3BO3. The molecular form of H3BO3 was more reactive with MgO in releasing Mg2+ ions than B(OH)4–. 11B-NMR results indicated that trigonal B ([3]B) was predominant over tetrahedral B ([4]B) in solid residues after sorption of H3BO3. The molar ratio of [4]B/[3]B increased with H3BO3 sorption density. XRD patterns for the solid residues were assigned to Mg(OH)2 and peaks broadened with increasing H3BO3 sorption density, except for (hk0) planes due to c-axis lattice strain induced by incorporation of H3BO3 between layers. These results indicated that H3BO3 interfered in the c-axis stacking of in Mg(OH)2. Molecular H3BO3 acted as a trigger when reacting with the MgO surface, releasing Mg2+ to produce an unstable complex leading to the precipitation formation of Mg(OH)2, which is a sink for the immobilization of H3BO3/B(OH)4–..
87. 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, The formation and structural evolution of fungal mediate biogenic birnessite are dynamic processes. Although the associations of Zn
with the pre-formed biogenic Mn oxides are relatively well understood, the reactivity of the intermediate precipitate at the initial stage
of Mn bio-oxidation appears to differ from the final precipitate. In the present work, Zn sorption during precipitation of biogenic Mn
oxides was investigated contrasting Zn sorption to pre-formed biogenic Mn oxides, using the Mn-oxidizing fungus Paraconiothyrium
sp. WL-2. A substantially higher Zn uptake was found during precipitation of biogenic Mn oxides compared to Zn sorption to
pre-formed biogenic Mn oxides. The presence of Zn during Mn oxidation resulted in a biogenic Mn oxide with reduced ordering in
the c-axis. The precipitate was identified by X-ray diffraction (XRD) as a layer-type Mn oxide with structural properties similar to
hexagonal birnessite. Extended X-ray absorption fine structure (EXAFS) spectroscopy showed that Zn forms triple-corner-sharing
tetrahedral coordination (IVTCS-Zn) complexes on the surface of birnessite, which may inhibited layer stacking of birnessite in the
final products. This study emphasizes the importance of the intermediate precipitates on Zn sorption, and provides insight regarding
the dynamic interaction between Zn and Mn oxide in the process of microbiological oxidation. Supplemental materials are available
for this article. Go to the publisher’s online edition of Geomicrobiology Journal to view the supplemental file..
88. 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.
89. 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, A hydrotalcite-like compound prepared through chemical deposition using calcined dolomite as the magnesium source (D-LDH) was applied to remove borate. D-LDH calcined at different temperatures was characterized by specific surface area measurements, scanning electron microscope images, X-ray diffraction (XRD) patterns, and fourier transform infrared (FTIR) spectra to optimize the calcination temperature and maximize the sorption capacity of borate. Greater sorption density of borate was observed at higher calcination temperature, and the sample calcined at 700 °C showed the maximum sorption density. In addition, the sorption density of borate by D-LDH calcined at 700 °C decreased with increasing initial pH. The solid residues after the sorption of borate were characterized by FTIR, 11B-NMR (11Boron nuclear magnetic resonance), and XRD to explore the sorption mechanism of the calcined product at 700 °C..
90. 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, Natural dolomite was calcined at 700–900°C under air and an Ar gas flow atmosphere to characterize its sorbency potential for borate. A sequential decarbonation occurred with increase in calcination temperature, that is, transformation of CaMg(CO3)2 to MgO and CaCO3 up to 700°C and CaCO3 to CaO from 700 to 900°C. The surface molar ratio of Ca/Mg decreased from 1.6 to 0.6 by calcination at more than 700°C, owing to the crystal growth of MgO toward the surfaces. MgO crystal growth is responsible for hydration leading to borate co-precipitation. The sorption density of borate was greater with the calcined products at 700°C than 800–900°C and under an Ar-gas flow system rather than for static air at the same temperatures. The surface reactivity of the calcined dolomite with borate in the aqueous phase was affected by CO2 emitted in the decarbonation at higher temperatures..
91. 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, Biogenic birnessite (BB), the stable form of manganese in the natural environment that originates from microbial oxidation, could be used as a starting material to prepare nanocrystalline lithium manganese oxide (LMO) by solid-state reaction for Li+ recovery. In the present work, the effects of calcination temperature on Li+ adsorption density were systematically investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption isotherms, and sorption isotherms of Li+ ions. Increase in calcination temperature causes phase transformation, resulting in changes of crystal compositions. Formation of Li4Mn5O12 was observed at 350°C. An increase in calcination temperature from 350 to 450°C results in a decrease in Li4Mn5O12 phase with an increase in Li2MnO3 phase, and the sorption density of Li+ decreased from 4248 mmol/kg to 2842 mmol/kg. The sorption density of Li+ is mainly affected by the contents of Li4Mn5O12 phase. The LMOs prepared from BB show higher Li+ sorption density compared with chemically synthesized acidic birnessite. This is because phase transformation happened on poorly crystalline BB at a relatively lower calcination temperature, facilitating the formation of Li4Mn5O12 phase, which is the mainly contributor for Li+ sorption from the aqueous solution..
92. 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.
93. 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.
94. 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.
95. 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, The CO2-blown integrated coal gasification combined cycle (IGCC) is a promising electric power generation technology that will reduce CO2 emission, due to its high efficiency. Recent studies have found that base metals improve the coal char gasification in cases when they can interact with the char matrix at an atomic level. In this paper, we clarified the effect of heavy medium separation, which is one of the most popular coal cleaning technologies, on the CO2 char gasification. Before sink and float test and thermogravimetric analysis, Datong Coal from China was ground to below 20 mesh, which is a size usually used for a coal cleaning process. The float and sink test revealed that the highest separation efficiency would be obtained at a specific gravity of 1.45. The ash content would be reduced dramatically from 10.2% to ca. 4% and about 85% of combustibles would be recovered. The chars derived from different specific gravity fractions showed different gasification reactivity; the char from heavier fraction has gasification reactivity higher than the lighter fraction-derived char. This tendency agrees with the ash content; the heavier fraction has a higher ash content. Removal of ash from well-ordered holes in Fusinite and Semi-fusinite in Inertinite might increase the gasification reactivity.

.
96. 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.
97. 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.
98. 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.
99. 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, With the recent Fukushima incident, there is an urgent need to find cost effective and workable permeable reactive barrier (PRBs) for the
remediation/retardation of problematic radionuclides. Catfish bones were calcined at various temperatures (4001100°
C) to remove the organic
matter (87.1 mg·g¹1) and to change the structural properties of the hydroxyapatite (HAP). Increasing temperatures increased the HAP
crystallinity as indicated by a decrease in lattice strain (0.0098 to 0.00135) and an increase in crystallite sizes (5.0 © 10¹8 to 7.7 © 10¹8 m).
There was also an observed decrease in specific surface areas (98.9 to 0.99m2·g¹1) and increase in particle sizes (50 to 1000 nm). The sorption
densities of Sr2+ decreased with increasing calcination temperatures, from 0.34 to 0.05 mmol·g¹1. However, once normalized for surface area,
the sorption densities increased from 1.8 to 5.9 mmol·m¹2. Overall, this research has important implications for the design of hydroxyapatite
PRBs with higher calcination temperatures producing a more reactive material with larger particle sizes for increased permeability. Lower
calcination temperatures produced amorphous HAP material, which released more aqueous PO4
3¹ and resulted in the precipitation of strontium
phosphates, ultimately reducing the permeability of PRBs..
100. 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, Use of MgO for repeated calcination with regard to its sorption density for F- and chemical stability was examined. Magnesium oxide was produced by the calcination of MgCO3 at 1273 K for 1 h. The sorption of 9.82 mM F- on the calcined product and the calcinations of solid residues were carried out five times to evaluate trends in sorption density for F- and the stability of the chemically regenerated sorbents. The order of sorption density of F- (Q/ mol•g-1) apparently seems to depend on the specific surface area. However, Q’ values after normalization of the sorption density for the specific surface area (Q’/ mmol•m-2) were found to be correlated with the solid basicities of the calcined products which were derived from CO2-TPD curves for the calcined products. The number of weak base sites, calculated from the peak intensity at 373 K in CO2-TPD, was considered to be responsible for the removal of F- through hydration. Large quantities of NaMgF3 and elemental Mg were evaporated by the calcination at 1273 K of the solid residues formed after sorption of F-..
101. Keiko Sasaki, Koichiro Takatsugi, Olli H. Tuovinen, Spectroscopic analysis of the bioleaching of chalcopyrite by Acidithiobacillus caldus , Hydrometallurgy, 127-128, 116-120, 2012.07, The formation and consumption of elemental S were investigated in the bioleaching of chalcopyrite within and without a CE dialysis membrane in Acidithiobacillus caldus cultures. The bacteria were supplemented with tetrathionate outside the membrane. XPS analysis showed that monosulfide species and elemental S were formed on CuFeS2 surface regardless of the enclosure in the dialysis membrane. They diminished over time in the inoculated systems. In the membrane enclosure, colloidal S partially dissolves and can pass the dialysis membrane for bacterial oxidation to sulfuric acid. Anaerobic pre-oxidation of CuFeS2 by Fe3+ produced S-rich deposition on mineral surface. The solubilization of Cu from membrane-enclosed pre-oxidized chalcopyrite in the A. caldus culture was much slower as compared to direct contact with bacteria. The difference is attributed to slow diffusion through the dialysis membrane as well as clogging caused by polymerized S on the inside of the membrane..
102. 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.
103. 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, Application of microorganisms as surface modifiers in flocculation has generated a great deal of interest in recent times. The surface properties such as zeta-potential and hydrophobicity of minerals and microorganisms play a major role in determining the adsorption of microorganisms onto the minerals and hence the efficiency of flocculation. The utility of microorganisms, including Escherichia coli (wild-type and genetically modified strain Sip), Arthrobacter nicotianae, Bacillus licheniformis, and Pseudomonas maltophilia, has been evaluated by measuring their zeta-potentials and carrying out adsorption and flocculation experiments. Of the tested microorganisms, adsorption of E. coli strain Sip significantly modified the quartz surface. The zeta-potential of the quartz became highly positive at acidic pH, and its IEP (isoelectric point) was shifted from pH < 2 to pH 4.3. Moreover, the settling velocity of the bio-treated quartz reached its maximum value at this pH. The number of cells adsorbed onto quartz was low at pH above the IEP due to the identical surface charges of the mineral and bacterial cells. This led to a repulsive force between the mineral particles and bacterial cells, which hindered the adsorption process. For all of the studied strains, the settling velocity of bio-treated quartz was high at their respective IEPs. An interaction model of microorganisms is proposed to explain the flocculation behavior of bio-treated quartz. Potential energies were calculated using the DLVO theory, and the results were found to be in good agreement with the flocculation tests. The settling velocity of the bio-treated quartz was maximized at pH close to the IEP of microbial cells. Interaction between cells is identified as the most likely cause of flocculation of bio-treated quartz..
104. 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.
105. Characterization of passivation layers in bioleaching of sulfides.
106. 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.
107. 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, Biomineral hydroxyapatite (Bio-HAp) produced
by Serratia sp. has the potential to be a suitable material for the
remediation of metal contaminated waters and as a radionuclide
waste storage material. Varying the Bio-HAp manufacturing
method was found to influence hydroxyapatite (HAp) properties
and consequently the uptake of Sr2+ and Co2+. All the Bio-
HAp tested in this study were more efficient than the commercially
available hydroxyapatite (Com-HAp) for Sr2+ and Co2+
uptake. For Bio-HAp the uptake for Sr2+ and Co2+ ranged from
24 to 39 and 29 to 78 mmol per 100 g, respectively.Whereas, the
uptake of Sr2+ and Co2+ by Com-HAp ranged from 3 to 11 and 4 to 18mmol per 100 g, respectively. Properties that increased metal
uptake were smaller crystallite size (<40 nm) and higher surface area (>70 m2 g1). Organic content which influences the structure
(e.g., crystallite arrangement, size and surface area) and composition of Bio-HAp was also found to be important in Sr2+ and Co2+
uptake. Overall, Bio-HAp shows promise for the remediation of aqueous metal waste especially since Bio-HAp can be synthesized
for optimal metal uptake properties..
108. 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, Bioleaching of enargite by the thermophilic iron-oxidizing archaea, Acidianus brierleyi, at 70 °C for 27 days
yielded a 90.9% recovery of Cu and 5.9% recovery of As. The preferential dissolution of Cu compared to As was
mainly achieved by the formation of crystalline scorodite (FeAsO4·2H2O). Although the chemical valence of
As in enargite was confirmed to be As(III), most of the dissolved As was in the compound H3AsVO4. This
indicates that the H3AsIIIO3 released from the enargite was immediately oxidized to H2AsVO4
− in solution via a
catalytic reaction on the surface of the enargite. During the bioleaching process, dissolved Fe3+ was consumed
through the formation of precipitates, such as scorodite and jarosite ((M+)Fe3(SO4)2(OH)6), as well as the
oxidation of enargite. Even after the formation of scorodite had stopped due to the consumption of Fe3+,
As was further passivated in the absence of Fe3+. The co-sorption of Cu2+ and H2AsVO4
− on jarosite led to the formation of copper arsenate by a seed-forming effect. Subsequent secondary mineral precipitation
resulted in the formation of multi-precipitation layers consisting of scorodite, potassium jarosite, elemental
sulfur and copper arsenate, after most of the Cu had been recovered from the enargite by microbially induced
leaching..
109. 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, To maximize Cu recovery and minimize As release during the bioleaching of enargite (Cu3AsS4) by Acidianus
brierleyi at 70 °C, the initial Fe2+ ion concentration and pulp densitywere investigated in batch tests. A maximum
Cu recovery of 91.0±0.5%was obtainedwith an initial Fe2+ ion concentration of 1.8–2.7 g/L and a pulp density of
1.0%. As the immobilization of As depended on the formation of scorodite (FeAsO4·2H2O) and cupric arsenate, a
more rapid and stable As immobilization was achievedwith an initial Fe2+ ion concentration of 2.7 g/L. Thus the
initial Fe2+ concentration of 2.7 g/L and 1.0% pulp density provided for a combination of As precipitation and
N90% Cu recovery.When the initial Fe2+ concentrationwas increased, K-jarosite (KFe3(SO4)2(OH)6)precipitated,
leading to passivation of the enargite surface.When the initial Fe2+ concentration was lowered, the Cu recovery
was incomplete due to insufficient oxidation. Elevating the pulp density to 2.0% showed that the increase in Eh
significantly lagged behind the exponential phase in the planktonic cell growth curve. Pulp density also clearly
affected themakeup of secondary minerals in solid residues after the bioleaching of enargite. There is a tendency
for dissolved Fe3+ ions to readily precipitate as potassium jarosite at relatively smaller pulp densities and as
scorodite at relatively larger pulp densities..
110. 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, The effect of calcination temperature during production of magnesium oxide-rich phases from MgCO3 on the sorption of F− ions in the aqueous phase has been investigated. Magnesium oxide-rich phases were formed by calcination at over 873K for 1 h. Higher calcination temperatures produced more crystalline MgO with smaller specific surface area and provided larger values of the total basicity per unit surface area. The higher calcination temperatures lead to slower F− removal rate, and lower equilibrium F− concentrations, when the equilibrium F− concentrations are less than 1mmoldm−3. Larger total basicity per unit surface areamadethe reactivity with F− ions in aqueous phase more feasible, resulting in a greater degree of F− sorption. For equilibrium F− concentrations more than 1mmoldm−3, lower calcination temperatures favored the co-precipitation of F− with Mg(OH)2, probably leading to the formation of Mg(OH)2−xFx, and the achievement of larger sorption density. This is the first paper which describes the relationship between the solid base characteristics obtained by CO2-TPD for MgO with different calcination temperatures as a function of the reactivity of F− sorption in the aqueous phase..
111. Moriyasu NONAKA, Tsuyoshi HIRAJIMA and Keiko SASAKI, Upgrading of Low Rank Coal and Woody Biomass Mixture by Hydrothermal Treatment, Fuel, in press, 2011.04.
112. Keiko SASAKI, Hitoshi TAKAMORI, Hitoshi YOSHIZAKA, Sayo MORIMAYA, Tsuyoshi HIRAJIMA, Effect of Saw Dusts on Borate Removal from Groundwater in Bench-scale Simulation of Permeable Reactive Barriers Including Magnesium Oxide, J. Hazard. Mater., 185, 1440-1447, 2011.01, Effective immobilization of boron in groundwater is a major challenge. Permeable reactive barrier (PRB)
column tests for removal of borate have been investigated using MgO agglomerates as the primary reactive
material over 40 weeks. Additionally, saw dust was also blended with MgO agglomerates to facilitate
for borate removal in this system. Boron accumulation was more than 1.6 times greater in the presence of
saw dust, although MgO alone performed well. Increased boron accumulation in the presence of saw dust
was primarily due to higher porosity of the PRB column, decreasing the impact of secondary Mg(OH)2
passivating layers and leaving more reactive sites on MgO agglomerates. In addition, Mg2+ ions released
from MgO agglomerates are complexed with carboxylic acids leached from saw dusts. This sequestration
prevents the formation of bulky Mg(OH)2 which is an ineffective sorbent for borate and covers the surfaces
and passivating reactive sites on the MgO agglomerates. The morphologies of Mg(OH)2 precipitated
in the PRB column were also significantly affected by the presence of saw dust, with crystallization of
needle-like particles of Mg(OH)2 was prevented by Mg2+ ions–organic ligand complexation..
113. 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.
114. 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.
115. 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.
116. 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.
117. 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.
118. 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.
119. 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, The purpose of this study was to characterize secondary minerals that were formed in the bioleaching of
enargite (Cu3AsS4) by Acidithiobacillus ferrooxidans. Two parallel cultures were used: one was adapted to
arsenic in the growth medium and the other was wild-type. The progress of the solubilization of As in A.
ferrooxidans cultures was stepwise and different from that observed in the non-adapted culture. In contrast,
the bioleaching of Cu and Fe from enargite was not affected by prior adaptation of the culture. Minor
presence of jarosite was observed by X-ray diffraction (XRD) in solid residues after the bioleaching, and no
other peaks of secondary crystalline minerals were detected. The relative intensities of As 3d and Fe 2p to Cu
2p in X-ray photoelectron spectroscopy (XPS) for the solid residues were at maximum at 46 days after the
bioleaching with As-adapted A. ferrooxidans. The results from the examination of solid residues with XPS,
transmission electron microscopy with energy-dispersive microprobe (TEM-EDS) and XRD after 46 days of
contact with As-adapted A. ferrooxidans showed the presence of metastable, amorphous ferric arsenate as an
intermediate on the surface of enargite and minor amounts of jarosite. The amorphous ferric arsenate phase
did not appear to have an adverse effect of the dissolution of Cu from enargite..
120. 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.
121. 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.
122. 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.
123. 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.
124. 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.
125. 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.
126. Anggoro T MURSITO, Tsuyoshi HIRAJIMA, Keiko SASAKI, Upgrading and Dewatering of Raw Tropical Peat by Hydrothermal Treatment, Fuel, 89, 635-641, 2010.01.
127. 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.
128. 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.
129. 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.
130. Treatment of Heavy Metals in a Constructed Wetland, Kaminokuni, Hokkaido
-Role of Microorganisms in Immobilization of Heavy Metals in Wetland Soils-.
131. Treatment of Heavy Metals in a Constructed Wetland, Kaminokuni, Hokkaido
-Accumulation of Heavy Metals in Emergent Vegetations-.
132. 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.
133. 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.
134. 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.
135. 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.
136. 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.
137. 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.
138. 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.
139. 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.
140. 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.
141. 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.
142. 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.
143. 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.
144. 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.
145. 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.
146. 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.
147. 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.
148. Production of Bio-Coal Fuel from Low Rank Coal and Woody Biomass Mixture by Using a Bench-Scale Continuous Hydrothermal Equipment.
149. 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.
150. 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.
151. 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.
152. , [URL].
153. 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.
154. 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.
155. 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.
156. 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.
157. Activation of manganese-oxidizing fungus with carbon fiber
- Fibrous shape is essential -.
158. 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.
159. 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.
160. 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.
161. 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.
162. 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.
163. 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.
164. 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.
165. 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.
166. 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.
167. 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.
168. 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.
169. 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.
170. 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.
171. K. Sasaki, O. Tanaike and H. Konno, Distinction of jarosite compounds by Raman spectroscopy., Can. Mineral., 36, 1225-1235, 1998.01.
172. K. Sasaki, Raman study of the microbially mediated dissolution of pyrite by Thiobacillus ferrooxidans., Can. Mineral., 35(4), 999-1008, 1997.01.
173. 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.
174. 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.
175. 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.
176. 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.
177. 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.
178. 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.
179. 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.
180. 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.
181. 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.
182. K. Sasaki, Effect of grinding on the rate of oxidation of pyrite by oxygen., Geochim. Cosmochim. Acta, 58, 4649-4655, 1994.01.
183. 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.
184. Wuhui Luo, Sasaki Keiko, Surfactant-modified montmorillonite by benzyloctadecyldimethylammonium chloride for removal of perchlorate
, Colloids and Surfaces A: Physicochemical and Engineering Aspects,, 481, 616-625.
185. Xinhong Qiu, Sasaki Keiko, Removal mechanism of polymeric borate on calcined LDHs including different divalent metals
, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 10.1016/j.colsurfa.2015.07.036.
186. Qianqian YU, Sasaki Keiko, Microwave-assisted synthesis of nanocrystalline lithium-ion sieve from biogenic manganese oxide: Effect of crystalline phase and morphology on the lithium adsorption capacity, Hydrometallurgy, 10.1016/j.hydromet.2015.10.002, 165 (2016) 118–124.
187. Mutia Dewi YUNIATI, Hajime Miki, Tsuyoshi Hirajima, Sasaki Keiko, Silicate Covering Layer on Pyrite Surface in the Presence of Silicon-Catechol Complex for Acid Mine Drainage Prevention, Materials Transactions, in press.
188. Mutia Dewi Yuniati, Sasaki Keiko, Tsuyoshi Hirajima, Naoko Okibe, Suppression of pyrite oxidation (AMD) by carrier microencapsulation using the liquid product of hydrothermal treatment of low rank coal, and electrochemical behaviors of the resultant encapsulating coating, Hydrometallurgy, 158 (2015) 83-93.
189. Wuhui Luo, Tsuyoshi Hirajima, Sasaki Keiko, Optimization of hexadecylpyridinium-modified montmorillonite for removal of perchlorate and revelation of overlooked sorption mechanism, Applied Clay Science, in press.
190. Hajime Miki, Tsuyoshi Hirajima, Sasaki Keiko, The Catalytic Effect of Silver on Arsenic Containing Copper Sulfide Dissolution in Acid Solution, Hydrometallurgy, in press..
191. 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, A powdery lithium ion sieve (HMO) derived from biogenic birnessite was homogeneously integrated in sodium
alginate (AL) beads. The composite beads were then characterized and their Li+ adsorption properties were investigated.
Scanning electron microscopy–energy dispersive spectroscopy analysis showed that the HMO particles
were homogeneously dispersed in the AL beads even after drying. The adsorption isothermof Li+ adsorption
to HMO encapsulated in AL beads (HMO–AL) was well fitted by the linear Langmuir model, and the beads
showed a maximum adsorption capacity of 3.61 mmol/g based on HMO, which is comparable with the value
of the original powdery HMO. Kinetic studies revealed that adsorption of Li+ follows a pseudo-second-order
model with rate constant k2 = 2.8–11.9 × 10−3 g/(mmol min) for the initial Li+ concentration range
2.56–4.23 mM. Diffusion of Li+ from aqueous solution to the HMO particle through the Ca–AL network is the
rate-limiting step for Li+ adsorption to HMO–AL beads. The HMO-AL beads enhanced the handling efficiency
for Li+ adsorption and reused without significant reduction of Li+ adsorption efficacy..
Presentations
1. 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.

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2. 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.
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3. 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.
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4. 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..
5. 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..
6. 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..
7. 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.
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8. Wuhui Luo, Sasaki Keiko, Synergistic adsorption of Sr2+ and ClO4− on alginate-encapsulated organo-montmorillonite, Hybrid Materials 2017, 2017.03.
9. Sasaki Keiko, NATURAL ATTENUATION OF ARSENATE-CONTAMINATED RIVER IMPACTED BY ACID MINE DRAINAGES: CHARACTERIZATION OF SUSPENDED PARTICULATE MATTERS , ICHMET 2016, 2016.09.
10. 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.
11. Sasaki Keiko, Bioleaching of Cu from enargite using thermoacidophilic iron-oxidizing archaeon, Acidianus brierleyi: Spectroscopic study for stabilizing As, Copper 2016, 2016.11.
12. 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.
13. 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.
14. 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.
15. 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.
16. 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.
17. 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.
18. 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.
19. Sasaki Keiko, (invited) Spectroscopic and microscopic investigation in biohydrometallurgy , International Biohydrometallurgy Symposium 2015 (IBS 2015), 2015.10.
20. 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.
21. 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.
22. Sasaki Keiko, Spectroscopic and Microscopic Investigation for Biohydrometallurgy, 21st International Biohydrometallurgy Symposium (IBS 2015), 2015.10.
23. 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.
24. Yu Takaki, Xinhong Qiu, Tsuyoshi Hirajima, Sasaki Keiko, Removal mechanism of arsenate by hydrocalumite depending on arsenate concentration, EUROCLAY 2015, 2015.07.
25. Wuhui Luo, Sasaki Keiko, Synthesis of surfactant-modified montmorillonites for adsorption of perchlorate, EUROCLAY 2015, 2015.07.
26. 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.
27. 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.
28. Yu TAKAKI, Paulmanickam KOILRAJ, Tsuyoshi Hirajima, Sasaki Keiko, Adsorption Characteristic of Arsenate on Delaminated Layered Double Hydroxides, Euroclay2015, 2015.07.
29. 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.
30. 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.
31. Wuhui Luo, Sasaki Keiko, Evaluation of BDTAC, DDAC and BDOAC-modified montmorillonites for perchlorate removal, Hybride Materials 2015, 2015.03.
32. KOILRAJ PAULMANICKAM, Sasaki Keiko, Srinivasan KANNAN, Amino acid assisted solvothermal synthesis of layered double hydroxides, Hybride Materials 2015, 2015.03.
33. Sasaki Keiko, Biohydrometallurgy of enargite: A spectroscopic investigation of bioleaching by thermoacidophilic iron-oxidizing archaeon, Acidianus brierleyi , IGO-2015, 2015.01.
34. Sasaki Keiko, Sequential modification of montmorillonite using DDAC and BDOAC for removal of perchlorate: Effect of DDAC dosage
, CINEST 2014, 2014.12.
35. 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.
36. 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
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  • 2009.04.
  • 2008.07.
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  • 2008.08.
  • 2007.04.
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  • 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.