掲載種別：研究論文（学術雑誌）   出版者・発行元：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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掲載種別：研究論文（学術雑誌）   出版者・発行元：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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掲載種別：研究論文（学術雑誌）   出版者・発行元：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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出版者・発行元：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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掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Sustainable Chemistry and Engineering  

Metals are key components of modern devices; however, available resources of these metals are limited. In this study, we used machine learning (ML) to curate ionic liquids (ILs) that are suitable for metal extraction. We proposed classification and regression models to unravel hidden patterns between IL structures and their specific properties, i.e., metal selectivity and eco-toxicity. Evaluations of ML models using cross-validation indicate that the models were reliable, as described by the accuracy score (0.82) and R2value (0.76). The models also revealed that the metal selectivity of ILs was determined by the cation and anion structures, and the eco-toxicity level was primarily affected by the cation structures. Guided by predictions from the trained models, we selected three ILs (out of the 150 IL structures we initially proposed) that have extraction selectivity toward platinum, lithium, and neodymium as well as low eco-toxicity. We then prepared the ILs in the laboratory and assessed their performance by standard solvent extraction. The experiments indicate that the recommended ILs from ML could selectively extract the targeted metals with high extraction efficiency (>80%), which demonstrates the feasibility of ML as a promising toolkit that can help accelerate innovations in metal extraction.

DOI： 10.1021/acssuschemeng.2c03480

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掲載種別：研究論文（学術雑誌）   出版者・発行元：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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出版者・発行元：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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掲載種別：研究論文（学術雑誌）   出版者・発行元：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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出版者・発行元：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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掲載種別：研究論文（学術雑誌）   出版者・発行元：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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掲載種別：論文集(書籍)内論文   出版者・発行元：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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