Language：English   Publisher：Nuclear Science and Engineering  

High-temperature gas-cooled reactors (HTGRs) are being developed not only for electricity generation but also to produce hydrogen, leveraging the high outlet coolant temperature up to 950°C from the reactor core. To achieve this condition safely, the power density distribution within the core should be optimized through effective in-core fuel management. Depending on the reactor’s intended application and core design, the neutronic parameters should be calculated for each core configuration. In this present study, high-fidelity simulations based on the Monte Carlo (MC) method were performed to predict the key neutronic parameter of multiplication factors k<inf>inf</inf>. Although it produces highly accurate results, the MC method is time-consuming and computationally intensive, particularly for large-scale parametric studies. This initial study proposes using surrogate models developed through machine learning techniques to predict important neutronic parameters more efficiently. The current stage focuses on developing a predictive model at the lattice level of HTGRs. The widely used ensemble method Random Forest regression was adopted. A dataset consisting of approximately 640 samples was prepared and used for model training and validation. The model’s performance was evaluated using the coefficient of determination R² and the root-mean-square error, yielding values of 0.998 and 0.011, respectively. Furthermore, when applied to predict the k<inf>inf</inf> values, the model demonstrated good agreement with MC simulation, with prediction errors ranging from 0.9% to 5.5%, depending on the uranium enrichment and the fuel packing fraction.

DOI： 10.1080/00295639.2026.2702758

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Rsc Sustainability  

An efficient two-phase leaching system using a hydrophobic deep eutectic solvent (DES) composed of 2 mol of 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and 1 mol of tri-n-octylphosphine oxide, with H<inf>2</inf>O<inf>2</inf> as the aqueous phase, was developed for the selective recovery of Li, Co, Ni, and Mn from spent lithium-ion batteries. Under optimized conditions (80 °C, 30 min, 500 rpm, 10 mg per mL black mass loading, DES-to-aqueous ratio 1 : 1, and 5 M H<inf>2</inf>O<inf>2</inf> as the aqueous phase), the two-phase leaching system achieved leaching efficiencies of 98% for Li, 94% for Co, 94% for Ni, 98% for Mn, with 73% Cu, 54% Al, and 76% Fe in the DES phase and minor amounts of Cu and Al in the aqueous phase, demonstrating pronounced phase-selective partitioning in a single-step process. The equilibrium pH (pH<inf>eq</inf>) of the aqueous solution controlled the metal transfer behavior from the DES to the aqueous phase: Li was fully stripped at pH<inf>eq</inf> ≤ 4, while Co, Ni, and Mn migrated to the aqueous phase at pH<inf>eq</inf> < 2. Furthermore, the DES exhibited stable performance over three successive cycles without regeneration or stripping, confirming its recyclability and operational robustness.

DOI： 10.1039/d5su00657k

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Publisher：Solvent Extraction Research and Development Japan  

Current industrial gold extraction processes primarily rely on toxic solvents and additives, which, despite their high efficiency, pose significant environmental and health hazards. Developing greener and more sustainable alternatives is therefore essential. Deep eutectic solvents (DESs) have recently gained attention as promising green solvents due to their tunable physicochemical properties and potential for selective metal extraction. In this study, we introduce a novel type V DES composed of N,N-diethylbenzamide (DEBA) and thymol (Thy), designed using COSMO-RS-predicted solid–liquid equilibrium phase diagrams to ensure eutectic behavior. DEBA-Thy demonstrated outstanding selectivity for Au³⁺ across a broad concentration range, achieving extraction efficiencies above 97%, while those of Pt⁴⁺ and Pd²⁺ remained below 10%. Slope analysis indicated a 1:1 stoichiometry for the Au(DES) complex. Additionally, cytotoxicity testing showed an EC<inf>50</inf> value of 72.09 µmol/L, suggesting lower toxicity compared to conventional solvents. These findings support DEBA-Thy as a promising, sustainable solvent for selective gold recovery.

DOI： 10.15261/serdj.33.1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACS Sustainable Chemistry and Engineering  

This study aimed to design materials for CO<inf>2</inf> capture with low regeneration temperatures without compromising the adsorption capacity (AC). Branched polyethylenimine (BPEI) functionalized with acrylonitrile (AN), 2-ethylhexyl acrylate (EHA), and butyl acrylate (BA) was impregnated onto fumed silica and tested for its adsorption and desorption properties. Higher functionalization degrees led to decreased desorption temperatures (DTs) from 73 to 97 °C to as low as 25 °C, which was attributed to the higher percentages of secondary amines upon functionalization and changes in the CO<inf>2</inf> adsorption mechanism. However, the adsorption capacities also decreased with functionalization. Bayesian optimization using machine learning models predicted optimal compositions of adsorbents for high adsorption capacities at low regeneration temperatures. The isothermal operation of CO<inf>2</inf> capture and release was also demonstrated to lower the energy requirement for CO<inf>2</inf> capturing systems. The functionalized BPEI materials steadily adsorb and release CO<inf>2</inf> for 20 cycles under isothermal conditions without any deterioration of the performance. BPEI 10,000 functionalized with AN, EHA, and BA offers a promising balance between AC and DT, making it suitable for industrial applications.

DOI： 10.1021/acssuschemeng.5c01250

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Industrial and Engineering Chemistry Research  

This study provides a practical approach for fast-screening DESs with properties suitable for critical metal extraction, integrating quantum chemical calculations, and machine learning (ML) predictions. We proposed 218 combinations of hydrogen-bond acceptors and hydrogen-bond donors, potentially forming DESs. The Random Forest and XGBoost classifier models achieved performance scores of 0.72 and 0.74, indicating robust predictive capabilities. Then, we curated the best three DESs suitable as extractants for critical metals that can also transform into a liquid phase at room temperature. The screening process involves two main steps, namely, (i) estimating the solid-liquid equilibrium phase diagram for each mixture to identify DES formation and (ii) using ML models to predict metal extraction selectivity. This study introduces 2,2-bipyridine:Phenol as a novel DES; the extraction system demonstrating high efficiency for nickel and cobalt over manganese and lithium, achieving 99% for Ni and 97% for Co after 60 min from an aqueous solution containing metals typical of spent lithium-ion batteries. The separation factor (SF) at 5 min results further confirm the system’s strong selectivity for Ni, indicating that Ni is extracted 5.18 times more efficiently than Co. These findings highlight the system’s potential for efficient metal separation.

DOI： 10.1021/acs.iecr.4c03736

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Publisher：Journal of the Iranian Chemical Society  

The low tolerance of zeolite in hot liquid water (HLW) could induce crystalline structure destruction and decrease the catalytic activity in aqueous system. Herein, we report modification on the zeolite external surface using organosilane to enhance the hydrophobicity. Pristine NaY was synthesized with a Si/Al ratio of 2.314. HY parent was prepared by ion exchange of NaY zeolite in ammonium chloride solution 0.1 M. External surface of HY zeolite was modified with 3-Aminopropyltriethoxysilane (APTES-HY). The structural stability of HY parent and modified HY after exposure to HLW was investigated at various times (0.5, 1, 2, 4, 10, and 72 h) at 200 °C. The modification with organosilane led to enhanced hydrophobicity and stability in the biphasic system. It was confirmed by XRD and SEM characterizations where the crystallinity and morphology of the treated APTES-HY were more preserved compared to the treated HY parent. XRF characterization showed that the ratio of Si/Al decreased as the time of HLW treatment increased. The decreasing trend of Si/Al ratio might be due to the hydrolysis of Si⁴⁺ species from zeolite framework. TGA characterization supports that organic compound protects the external surface of zeolite from degradation in a HLW environment. These studies are expected to upgrade the applications of hydrophobic zeolite as a catalyst in biomass conversion.

DOI： 10.1007/s13738-024-03157-w

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACS Sustainable Resource Management  

Developing an effective recycling process for reclaiming valuable metals from lithium-ion batteries is an urgent issue owing to increasing battery waste from electric vehicles. In this study, we developed a leaching method that enables the direct separation of lithium from other critical metals, namely, nickel and cobalt, using a two-phase system that consists of a deep eutectic solvent (DES) and water. The DES consisting of 4,4,4-trifluoro-1-phenyl-1,3-butadione and tri-n-octylphosphine oxide showed the highest leaching performance when combined with water. Several operational parameters, such as the aqueous fraction, solid-liquid ratio, reaction time, and operation temperature, were evaluated. The optimum results in the two-phase direct leaching system were obtained using a 1:1 DES-water ratio and 10 g/L solid-liquid ratio, reacted at 80 °C for 24 h. An in-situ stripping phenomenon was observed, revealing that lithium transferred from the DES phase to the aqueous phase. In the application of black mass leaching, the aqueous phase significantly enhanced Co, Ni, and Mn extraction into the DES phase and thus plays an important role in separating lithium from other metals. The efficiency of direct lithium leaching from the black mass reached 99% within 24 h.

DOI： 10.1021/acssusresmgt.4c00339

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

The utilization of ionic liquids (ILs) in metal extraction has been massively studied due to their excellent extraction ability, vast structural tunability, and low volatility. However, several ILs can be severely toxic, depending on the structure. It is significant to extract metal ions in a greener way for sustainability, yet the development of low-toxicity ILs for metal extraction remains a challenge. We prepared a series of potentially biocompatible ILs composed of amino acid ester (AAE)-based cations, with varying alkyl chain lengths and amino acid types and a fixed linoleate anion. An in vitro cytotoxicity study on HeLa cells indicates that the EC50 value of the synthesized ILs was ca. 2 orders of magnitude higher than that of commercial ILs (Aliquat 336 and Cyphos 104), suggestive of the low toxicity of the newly synthesized ILs. The ILs extracted the transition metals in the following order: Ni2+ > Co2+ > Mn2+. The separation factors for Ni/Co and Co/Mn ranged from 0.8 to 55 and from 0.6 to 50, respectively. In addition, l-leucine butyl linoleate exhibited highly selective extraction toward Au3+ and Pd2+ over Pt4+ with separation factors for Au/Pt and Pd/Pt of 37 and 40 in 0.05 mol/L HCl, respectively. Thus, AAE-based ILs are promising biocompatible extractants for metals.

DOI： 10.1021/acssuschemeng.4c01799

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1080/00219592.2022.2153547

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Publishing type：Research paper (scientific journal)   Publisher：Results in Chemistry  

In-situ hydrogen production and CO2 conversion to fuels have attracted significant attention as rational solutions to alleviate energy crises and climate issues. However, the implementation of such technology in large-scale industrial applications is still hampered by its inefficiency, considering the large energy barrier. Therefore, the fabrication of extremely efficient catalysts has become the main challenge in this field. Carbon nanotubes (CNTs) have recently been recognized as an encouraging electrocatalyst for such a process. CNTs-based electrocatalysts revealed remarkable catalytic activity in water-splitting reactions, proving that these materials are promising candidates for electrochemical processes. Carbon nanotubes with electron acceptor attributes facilitate charge separation, resulting in improved catalytic activity. This is primarily due to its exceptional physicochemical properties, i.e., enormous surface area, superior electrical conductivity, good thermal properties, and high melting point. This review highlights recent advances in the application of CNTs and CNTs-based catalysts in hydrogen production and CO2 conversion, focusing on detailed discussions on their preparation, modification, characterization, and catalytic performances. In addition, several possible challenges for further improvement of the CNTs catalytic system are also highlighted.

DOI： 10.1016/j.rechem.2023.101037

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACS Omega  

To reduce the exploitation of mine resources and decrease the harm to the environment caused by urban electronic wastes, the recovery of critical metals in secondary resources is crucial. In this study, we have successfully developed an eco-friendly process to integrate the leaching and separation of cobalt (Co) from a spent lithium-ion battery (LIB) cathode using an amino acid-based aqueous biphasic system (ABS). We, for the first time, demonstrated a simple method for leaching a LIB cathode using only amino acids. In addition, we have investigated the leaching mechanism using the typical cathode active material lithium cobalt oxide (LiCoO2). Then, the Co was selectively extracted by a biphasic system (amino acid-PPG400-H2O). This novel process has an excellent prospect in the field of spent-battery recycling because of its eco-friendly and process-simplified advantages.

DOI： 10.1021/acsomega.2c06654

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Publishing type：Research paper (scientific journal)   Publisher：Solvent Extraction Research and Development, Japan  

Recycling platinum group metals from secondary resources such as spent automotive exhaust catalysts is promising for the circular economy. However, the selective separation of Pt over massive amounts of impurity metals such as Mg and Al is particularly challenging. In this study, non-aqueous direct leaching of platinum from a spent automotive catalyst (SAC) using hydrophobic ionic liquids, namely, trihexyl(tetradecyl)phosphonium chloride (P66614Cl) and trioctyl(dodecyl)phosphonium chloride (P88812Cl) with the aid of pre-loading hydrochloric acid/hydrogen peroxide was proposed. The more hydrophobic P88812Cl exhibited more efficient and selective leaching of Pt over Mg and Al. The recovery of Pt from the metal-loaded P88812Cl, and the reusability of the IL for SAC leaching were also demonstrated.

DOI： 10.15261/serdj.30.149

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Biochemical Engineering Journal  

Selectivity is a crucial factor for gold recovery from discarded cell phones. This is because discarded cell phones contain a large variety of metals. The use of biomaterials as gold adsorbents is attracting much attention because it is in accordance with sustainability goals. Here, we reported selective adsorption of gold on silk fibroin and its application to gold recovery from the actual leachate of discarded cell phones in a chloride medium. The experimental maximum gold-adsorption capacity of silk fibroin was 5.800 mg/g. Based on a kinetic study, the gold-adsorption mechanism followed the pseudo-second-order model with a rate constant (k2) of 0.077 g mg−1min−1. The adsorption fitted well with the Langmuir model, suggesting a monolayer adsorption mechanism. Despite the small adsorption capacity, silk fibroin showed remarkable selectivity toward gold in synthetic and actual leachate containing Pt4+, Pd2+, Al3+, Cu2+, Ni2+, Zn2+, Pb2+, and Fe3+ metal ions in 0.5 mol/L HCl. The gold uptake from the actual leachate of discarded cell phones was approximately 95 %. The gold loaded on the silk fibroin was completely desorbed by 0.1 mol/L thiourea.

DOI： 10.1016/j.bej.2022.108690

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Publisher：Materials Today Communications  

Sensor materials shall ideally demonstrate high sensitivity, accurate selectivity, and long durability. However, discovering such materials that simultaneously match industrial demands—e.g., simple preparation, simple calibration, and low cost—is quite challenging. In recent years, numerous endeavors have been attempted to deal with this quest, including incorporating zeolites into sensor materials. The hybrid sensor materials were found to exhibit excellent performances owing to the unique nature of zeolite. Zeolite-based sensor materials successfully identified various targets such as volatile organic compounds (VOCs), pollutants, moisture, base molecules, and radioactive species. Herein, we provide a review of the recent findings in the application of zeolites as sensor materials. The present review highlights several aspects, such as the fabrication methods, the role of zeolite frameworks, and some plausible mechanisms in the sensing process. Finally, we discussed possible future directions for the development of zeolite-based sensor materials that would agree with the industrial demands.

DOI： 10.1016/j.mtcomm.2022.104331

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Publishing type：Research paper (scientific journal)   Publisher：FlatChem  

Currently, oil is the most demanded and consumed energy source in the world. Nanofluid flooding has recently garnered considerable attention as an advanced chemical-based enhanced oil recovery (EOR) technology. In the last decade, two-dimensional nanomaterials have emerged as alternative nanoflooding agents because of their distinctive characteristics: (i) great ability to reduce interfacial tension, and (ii) highly elastic interfacial layer that could return to its original form, even after seriously disturbed, that avoid blockage in the reservoir. This review emphasizes the recent advances of several two-dimensional nanomaterials that have been investigated as nanoflooding agents. Compared with the commonly used homogeneous spherical nanoparticles, two-dimensional nanomaterial could generate amphiphilic Janus nanosheets with higher interfacial activity and emulsion stabilization, especially in amphiphilic states. Thus, two-dimensional nanomaterials are considered up-and-coming nanoflooding agents for obtaining a high oil recovery. Lastly, this review concludes with a summary and future outlook for EOR technology based on two-dimensional nanomaterials.

DOI： 10.1016/j.flatc.2022.100383

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Publisher：Journal of CO2 Utilization  

Capturing CO2 and converting it into fuels or fine chemicals is a promising way to deal with climate change issues and energy crises. However, the conversion of CO2 into hydrocarbons requires high activation energy owing to the stable C[dbnd]O bond. Therefore a catalyst with high performance is necessary to facilitate the chemical reactions. In recent years, it has been demonstrated that catalysts based on metal or metal oxides combined with zeolites have excellent performances in converting CO2 to various hydrocarbons and have the potential to be applied at an industrial scale. The present review article highlights the progress of zeolite-based catalysts in the CO2 conversion to hydrocarbon, i.e., gasoline, olefins, and aromatics products through modified Fischer-Tropcsh and methanol mediated pathways. The effect of zeolite properties, e.g., topology, acidity, morphology, crystallite size, extra framework cation and atom, and the pore structure, has been discussed. Also, several synthetic strategies for precisely adjusting the zeolite properties were demonstrated. Finally, the insight for future development was proposed.

DOI： 10.1016/j.jcou.2022.101969

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Industrial and Engineering Chemistry Research  

The era of electric vehicles is rapidly approaching, and therefore, it is crucial to provide a sustainable technology for ensuring the circular economy of lithium-ion batteries. In this study, we report the development of a novel aqueous biphasic system (ABS) comprising fully biocompatible components, that is, hydrophilic ionic liquids, amino acids, and organic acids, for the selective recovery of Co(II) and Ni(II) from Mn(II), which are critical metals in spent lithium-ion batteries. Separation of Co(II), Ni(II), and Mn(II) from sulfate media was successfully carried out using the ABS in a quite straightforward manner without any hazardous reagents or organic solvents. In addition, the plausible mechanism of metal ion separation within the ABS was elucidated. The regenerated ionic liquid in the ABS exhibited remarkably stable performance during use in three consecutive experimental cycles.

DOI： 10.1021/acs.iecr.2c00295

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Publisher：Journal of Materials Research and Technology  

The rapid and continuous depletion of fossil-based resources has boosted extensive research on alternative energy from renewable resources. In this sense, heterogeneous catalysts play an inevitable role in converting renewable resources into fuels. The performance of heterogeneous catalysts strictly depends on their structures and physicochemical properties. As a rule of thumb, heterogeneous catalysts with large specific surface areas possess more catalytic sites to enhance the overall catalytic performance. Nanoporous materials have emerged as highly active heterogeneous catalysts due to their large internal surface area, enabling a high density of active catalytic sites. The presence of nanopores also allows the selectivity towards the desired products. Herein, we provide a comprehensive review of recent advances of several typical nanoporous catalysts, i.e., zeolites, ordered mesoporous silica (OMS), metal- and covalent organic frameworks (MOFs and COFs), and nanoporous metals. Each nanoporous catalyst's characteristics and synthesis strategies are elaborated in detail, followed by discussions on their applications in various chemical processes to produce renewable fuels. Finally, challenges and opportunities for future improvement are provided.

DOI： 10.1016/j.jmrt.2022.02.033

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Separation and Purification Technology  

To establish more efficient and environmentally friendly lithium-ion battery (LiB) recycling processes, novel extractants derived from amino acids that enable better separation of Ni and Co were explored using density functional theory (DFT) calculations. DFT calculations and experimental validation indicated that of the three coordination sites—namely amine, amide, and carboxyl groups in the amic-acid ligands—the bond strength of the central amine group to the metal determines the Ni and Co separation performance. Based on the findings, the glycine-derived amic-acid extractant N-[N,N-di(2-ethylhexyl)aminocarbonylmethyl]glycine (D2EHAG) was applied for the recovery of Ni and Co from a spent automotive LiB leachate. Preferential and mutual recovery of Ni and Co from manganese by the D2EHAG-based recycling process was demonstrated. This study provides insights into the design of extractants that enable the mutual separation of Ni, Co, and Mn, and indicates the suitability of amic-acid extractants for LiB recycling processes.

DOI： 10.1016/j.seppur.2021.119898

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Publishing type：Part of collection (book)   Publisher：Engineering Materials  

Ordered nanoporous materials have attracted much attention due to their unique pore architecture, tunable physicochemical properties, which find applications in a broad spectrum of catalysis, separation, adsorption, drug delivery, energy storage, and sensing. In the past decades, the amount of research on ordered nanoporous materials has grown incrementally, resulting in diverse types of these materials with unprecedented structures. Herein, this chapter presents the recent advances of ordered nanoporous materials, including zeolites, ordered mesoporous materials (OMMs), metal–organic frameworks (MOFs), and covalent organic frameworks (COFs). Several vital aspects, i.e., structural and physicochemical properties, synthesis, and applications, are comprehensively discussed. Finally, challenges and prospects for future improvement are also elaborated.

DOI： 10.1007/978-3-030-85397-6_9

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