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InBiO 6 catalyst is employed for the electroreduction of CO 2. In 2 O 3 /Bi 2 O 3 interface effects exhibit low negative potential and high formate Faradaic efficiency. The study described presents an effective approach for developing high-performance CO 2 reduction electrocatalysts derived from metal-organic frameworks. [Display omitted] • InBiO 6 two-phase co-existing composites was designed for CO 2 electroreduction. • High FE formate (>80 %) in a wide potential window (−0.76 ∼ −1.26 V vs. RHE). • Long-term stability of 317h in H-type cell. • The introduction of Bi changes the electronic environment around In and activates the In sites. • DFT calculations reveal that the heterostructure benefit formate production. The electrochemical reduction of CO 2 (ERCO 2) has emerged as one of the most promising methods for achieving both renewable energy storage and CO 2 recovery. However, achieving both high selectivity and stability of catalysts remains a significant challenge. To address this challenge, this study investigated the selective synthesis of formate via ERCO 2 at the interface of In 2 O 3 and Bi 2 O 3 in the InBiO 6 composite material. Moreover, InBiO 6 was synthesized using indium-based metal–organic frameworks as precursor, which underwent continuous processing through ion exchange and thermal reduction. The results revealed that the formate Faradaic efficiency (FE formate) of InBiO 6 reached nearly 100 % at −0.86 V vs. reversible hydrogen electrode (RHE) and remained above 90 % after continuous 317-h electrolysis, which exceeded those of previously reported indium-based catalysts. Additionally, the InBiO 6 composite material exhibited an FE formate exceeding 80 % across a wide potential range of 500 mV from −0.76 to −1.26 V vs. RHE. Density-functional theory analysis confirmed that the heterogeneous interface of InBiO 6 played a role in achieving optimal free energies for *OCHO on its surface. Furthermore, the addition of Bi to the InBiO 6 matrix facilitated electron transfer and altered the electronic structure of In 2 O 3 , thereby enhancing the adsorption, decomposition, and formate production of *OCHO. [ABSTRACT FROM AUTHOR]

The purpose of the study is to examine the main methods of obtaining fertilizers and optimizing processes. Using methods of analysis, comparison, and experimentation, three main approaches to obtaining fertilizers were identified: grinding and mixing with potassium hydroxide (KOH), ultrafine grinding with chemical additives, and a complex method for processing caustobioliths. Comparative analysis of the investigated methods allowed for identifying their advantages, disadvantages, and effectiveness. The key result was the ability to determine the most effective method for producing humate-containing fertilizers from brown coal, depending on specific production conditions and requirements. The results of the study showed that the ultrafine grinding process with chemical additions, such as urea and alkali metal hydroxides, showed promising potential for creating highly effective humate-containing fertilizers from brown coal, in addition to the comparative analysis. After thorough optimization, this technique showed improved fertilizer utilization and superior plant uptake, making it a strong contender for sustainable farming methods. Nevertheless, achieving optimal results requires detailed process parameter optimization. The study underscores the importance of using brown coal in humate-containing fertilizer production as an environmentally safe and sustainable approach. The results can contribute to further development and improvement of humate-containing fertilizer production methods, promoting sustainable agriculture and increased crop productivity. [ABSTRACT FROM AUTHOR]

The removal of heavy metal ions from wastewater often necessitates the use of ion exchange resins. Current methods for assessing ion exchange efficiency are indirect and destructive. Some heavy metal ions, such as Cu2+ and Ni2+, are paramagnetic and influence the NMR relaxation times of water protons. NMR relaxometry can therefore be utilized to track the removal of these ions by ion exchange resins. In this study, we use relaxometry to monitor in situ the loading with Ni2+ and Cu2+ of Amberlite IR120 and Dowex Marathon MSC resins, with the resin column inserted into a low‐field NMR device. The multiexponential transverse relaxation curves were fitted using a biexponential model. Before and during the loading of the resin, the water with the slowest relaxation corresponds to treated water (free of Ni2+ or Cu2+) flowing between the resin beads. After saturation, the slowest fraction corresponds to the untreated solution (containing Ni2+ or Cu2+) flowing between the resin beads saturated with paramagnetic ions. The evolution with time of the transverse relaxation rate and the amplitude of the slowly relaxing water fraction shows a clear transition, occurring later at the bottom of the resin bed compared with the middle and top. This is interpreted as an indication of the saturation of the studied zone with paramagnetic ions, confirmed by the quantification of Ni2+ or Cu2+ in the effluent using AES spectroscopy. This proof‐of‐concept study demonstrates that NMR relaxometry can be used in situ to monitor the loading of a resin bed with paramagnetic ions. [ABSTRACT FROM AUTHOR]

At the Fukushima Daiichi Nuclear Power Station site, crystalline silicotitanate (CST) ion exchangers containing sodium ions (Na+) as exchange ions are used as an adsorbent to remove radioactive cesium (Cs) and strontium (Sr) from groundwater and contaminated water. The ion exchange reactions to remove Cs+ and Sr2+ compete with the reactions with other cations in the water sources. Since the groundwater and contaminated water have low concentrations of metal cations, the influence of competitive ion exchange reactions with protons (H+) is relatively large in the removal of Cs+ and Sr2+ from the water. In this paper, the H+/Na+ ion exchange property of the aqueous solution-CST system was evaluated. Results of batch tests were used to draw the isotherm and Kielland plot for the H+/Na+ ion exchange. The thermodynamic equilibrium constant K and the standard Gibbs energy ΔG0 of the H+/Na+ ion exchange reaction were evaluated from the Kielland plot. CST exhibited high H+ selectivity in the H+/Na+ ion exchange reaction. The values of K and ΔG0 were determined to be 7.3 × 104 and − 28 kJ mol−1, respectively. The selectivity of CST for H+ decreased with increasing H+ concentration on the ion exchange sites in CST. [ABSTRACT FROM AUTHOR]

Removal of Na+ is a very important step in the SiO2 aerogel preparation using water glass as precursor, which has a significant effect on the structure and properties of aerogel. In this study, three methods (Solution-crystallization, Water washing, and Ion exchange) were used to remove Na+ from the system and investigated the effects of different methods on the aerogel properties. The results show that all three aerogels have low bulk density (<0.075 g/cm3), low thermal conductivity (≤0.015 W/(m·K)), and well hydrophobicity (θ ≥ 137°). Among them, Na+ exists in the sol in the sodium removal process by water washing and effects the uniformity of gel network. The samples for sodium removal by solution-crystallization show better hydrophobicity and poorer high-temperature stability, which is related to the presence of abundant hydrophobic groups (Si-OC2H5) on the gel surface. The microstructure and the pore size distribution of the aerogels prepared by ion exchange are uniform, which makes them have optimal comprehensive performance. The mechanism of solution-crystallization effect in the process of sodium removal was explored, providing a workable idea for low-cost preparation of SiO2 aerogel. Highlights: Water glass was chosen as the inorganic silica source to prepare SiO2 aerogel with good performance. The effects of different sodium removal methods on the properties of aerogels were explored. The mechanism of solution-crystallization effect in the process of sodium removal was explored. [ABSTRACT FROM AUTHOR]

To find a novel resin to remove Co(II), the adsorption behaviour of Co(II) from the simulated acid leaching solution was investigated by ion exchange with AG®50W-X4 resin. Parameters such as reaction time, HCl concentration, and resin concentration affected the loading efficiency of Co(II) by AG®50W-X4 resin were tested. The adsorption behaviour of Co(II) strongly depended on HCl and resin concentration while reaction time was little effect on the loading percentage of Co. The loading behaviour of Co(II) into the resin fitted well with the Langmuir adsorption isotherm and the loading capacity for Co(II) was found at 29.8 mg/g. Moderate HCl solution was effective in eluting Co(II) from the loaded AG®50W-X4 resin. The obtained results investigated that AG®50W-X4 resin was a promising resin to absorb Co(II) from the low acid leaching solution of the spent lithium-ion mobile phone batteries. [ABSTRACT FROM AUTHOR]

AbstractAs global demand for stainless steel rapidly increases, the supply of minerals such as nickel, manganese, and chromium becomes more critical. To shift mineral peak production and delay scarcity of alloying minerals, recycling rates of minerals need to increase. Development of simple and cost-effective techniques for critical mineral production and recovery from industrial wastewater will lead to enhance the current recycling rate of the mineral and reduce potential hazards of industrial wastewater bearing high concentrations of minerals. In this study, ionic metal-organic framework (iMOF)-based sorbents are successfully designed for critical metal ion extraction from aqueous solution. The iMOFs are highly stable in aqueous solution over wide pH ranges, indicating that they are suitable for use in industrial wastewater with harsh chemical environments. The sorption capacity of iMOFs towards Ni reaches 34.1 mg/g with a removal efficiency of >99.9%. Notably, complete extraction of Ni takes place within 5 min, which is much faster compared to other sorbents. Moreover, the iMOFs can simultaneously coextract multiple minerals, proving their effectiveness as general sorbents for critical mineral recovery. [ABSTRACT FROM AUTHOR]

High‐purity rare earth (REEs) materials are key raw materials for the development of cutting‐edge technologies. However, due to similar physical and chemical properties, separating adjacent REEs from actual samples faces a formidable challenge. To overcome this challenge, an ion‐microporous metal–organic framework (ATZ‐BTC‐Zn; MOFs) is designed and synthesized, featuring densely packed nano‐trap pockets constructed from non‐coordinating carboxyl and amino groups. The synergistic effect of open nano‐trap pockets and suitable ions channel in ATZ‐BTC‐Zn is highly responsive to the size variation of lighter REEs. Notably, the configuration of Zn(H2O)62+ counterion in ATZ‐BTC‐Zn is similar to lanthanide hydrated ions (Ln(H2O)63+), facilitating the efficient ion exchange between them in the high‐speed ion transport channel. This accelerates the diffusion of REEs within the MOF pores, enhancing the utilization of active adsorption sites and promoting the efficient capture of adjacent REEs by nano‐traps. The binary model experiments show high separation factors for adjacent REEs (SFLa/Nd = 908, SFCe/La = 543), demonstrating efficient separation by ATZ‐BTC‐Zn in one step. This capability achieves the selective separation of adjacent REEs in tailings wastewater, providing a strategy to infer the compatibility between MOFs and REEs. [ABSTRACT FROM AUTHOR]

Coordination cages and their encapsulated cargo can be manoeuvred between immiscible liquid layers in a process referred to as phase transfer. Among the stimuli reported to drive phase transfer, counterion exchange is the most widespread. This method exploits the principle that counterions contribute strongly to the solubility preferences of coordination cages, and involves exchanging hydrophilic and hydrophobic counterions. Nevertheless, phase transfer of anionic cages remains relatively unexplored, as does selective phase transfer of individual cages from mixtures. Here we compare the phase transfer behaviour of two FeII4L6 cages with the same size and geometry, but with opposite charges. As such, this study presents a rare example wherein an anionic cage undergoes phase transfer upon countercation exchange. We then combine these two cages, and demonstrate that their quantitative separation can be achieved by inducing selective phase transfer of either cage. These results represent unprecedented control over the movement of coordination cages between different physical compartments and are anticipated to inform the development of next‐generation supramolecular systems. [ABSTRACT FROM AUTHOR]

Cellulose-based sorbents are promising materials for wastewater treatment due to their environmental friendliness, biodegradability, and high sorption capacity. This paper presents an overview of cellulose modification methods, including carboxylation, amination, oxidation, graphene, and plasma treatments, as well as combined approaches. Their effect on key physicochemical properties, such as porosity, morphology, and chemical stability, is considered. Examples from the literature confirm the effectiveness of modified cellulose sorbents in removing heavy metal ions and organic pollutants from wastewater. The analysis shows that combined methods allow for creating materials with improved characteristics that are resistant to extreme operating conditions. The main advantages and disadvantages of cellulose sorbents, as well as challenges associated with their scalability and cost-effectiveness, are discussed. The paper emphasizes the importance of further research to advance these materials as a key element of sustainable water treatment technologies. [ABSTRACT FROM AUTHOR]

Green hydrogen, produced by water electrolysis using renewable energy sources (RES), is an emerging technology that aligns with sustainable development goals and efforts to address climate change. In addition to energy, electrolyzers require ultrapure water to operate. Although seawater is abundant on the Earth, it must be desalinated and further purified to meet the electrolyzer's feeding water quality requirements. This paper reviews seawater purification processes for electrolysis. Three mature and commercially available desalination technologies (reverse osmosis, multiple-effect distillation, and multi-stage flash) were examined in terms of working principles, performance parameters, produced water quality, footprint, and capital and operating expenditures. Additionally, pretreatment and post-treatment techniques were explored, and the brine management methods were investigated. The findings of this study can help guide the selection and design of water treatment systems for electrolysis. [ABSTRACT FROM AUTHOR]

This paper investigates the elution behavior of scandium from D2EHPA (Di-(2-ethylhexyl) phosphoric acid)-impregnated resins that proceed with metal loading from acidic chloride solutions. D2EHPA resins stem from their recognized selectivity for Sc extraction from acidic solutions. This study focuses on the elution process after ion-exchange extraction and examines various elution systems to achieve selective Sc recovery. Among the tested elution media, fluoride-based systems were proven effective for Sc desorption. The elution of the resins was demonstrated in a column set-up, where complete and selective elution of Sc was achieved. Τhis study contributes to the advancement of Sc extraction methods from chloride solutions, offering valuable insights for industrial applications, especially emphasizing the importance of optimizing the elution step for achieving efficient recovery of Sc. [ABSTRACT FROM AUTHOR]

Nitridophosphates are subject of current research, as they have a broad spectrum of properties and potential applications, such as ion conductors or luminescent materials. Yet, the subclass of imidonitridophosphates has been studied less extensively. The primary reason is that the controlled N−H functionalization of nitridophosphates is not straight forward, making targeted synthesis more challenging. Inspired by the high‐pressure (HP) post‐synthetic modification of nitridophosphates, we present the topochemical HP deprotonation of phosphorus nitride imides using the high‐pressure polymorph β‐PN(NH) as an example. Additional incorporation of Zn2+ results in the first quaternary transition metal imidonitridophosphate ZnH2P4N8. The crystal structure was elucidated by single‐crystal X‐ray diffraction (SCXRD), energy‐dispersive X‐ray spectroscopy (EDX), powder X‐ray diffraction (PXRD) and solid‐state magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR). In addition, the presence of H as part of an imide group was confirmed by IR spectroscopy. The potential of this defunctionalization approach for controlling the N−H content is demonstrated by the preparation of partially deprotonated intermediates ZnxH4−2xP4N8 (x≈0.5, 0.85). This topochemical high‐pressure reaction represents a promising way to prepare, control and manipulate new imide‐based materials without altering their overall anionic framework. [ABSTRACT FROM AUTHOR]

The urgent need for economically viable and environmentally friendly desalination technologies to address global water scarcity is underscored. This study compares ion-exchange reverse osmosis (IX-RO) and ultrafiltration reverse osmosis (UF-RO) systems, examining their environmental impacts, energy efficiency, cost-effectiveness, and operational stability. The IX-RO system reduced water hardness and ion concentrations by 83%, while the UF-RO system achieved over 99% removal of total dissolved solids. Energy consumption for desalinating 1 m3 of Caspian Sea water was 1.49 kWh for IX-RO and 1.3 kWh for UF-RO. UF-RO's impact on human health, ecosystems, and resources was 1.62, 3.06, and 3.31 times greater than that of IX-RO, respectively. CO2 emissions were 192 kg CO2/m3 for UF-RO and 81.93 kg CO2/m3 for IX-RO. Over 68% of energy in both systems was from non-renewable resources, suggesting potential for utilizing Iran's solar and wave energy. The sensitivity analysis showed that citric acid had a significant environmental impact on UF-RO, while magnesium utilization had a notable impact on IX-RO. Water production costs were $0.06/m3 for IX-RO and $0.11/m3 for UF-RO. Over 20 years, the net present value was $172.8 million for IX-RO and $177.9 million for UF-RO, demonstrating their economic resilience. This study forms a basis for further research in the field. [ABSTRACT FROM AUTHOR]

90Sr is one of the highly radioactive and hazardous nuclides in nuclear waste liquids. The high water solubility and mobility of 90Sr2+ ions make it difficult to effectively remove 90Sr from the complex aqueous environment. Herein, K2SbPO6, a phosphatoantimonate ion exchange material with an excellent removal ability for Sr2+ ions, has been organically granulated with polyacrylonitrile (PAN) by an automated method to form K2SbPO6/PAN composite microspheres. The K2SbPO6/PAN microspheres with radiation resistance exhibit a high maximum adsorption capacity (qmSr) of 131.15 mg g−1 for Sr2+ ions and retain the high removal rate (RSr) in a wide pH range (pH = 3–12). It is important that K2SbPO6/PAN microspheres could efficiently treat Sr2+ ions solutions in a dynamic adsorption manner even at 970 bed volumes (RSr > 81%). This work paves the way for the preparation of low-cost ion exchange materials with the advantages of regular shape and easy operation by a simple and fast method and the practical application of powdered ion exchange materials. [ABSTRACT FROM AUTHOR]

Green hydrogen, produced through electrocatalytic water splitting, stands as a promising clean energy source for future large‐scale applications. Significant efforts have been dedicated to advancing high‐performance electrocatalysts for the oxygen evolution reaction and the hydrogen evolution reaction. Ion exchange, a widely adopted technology, facilitates the chemical transformation of materials by substituting the cations or anions in original electrocatalysts with guest ions. By finely tuning the atomic structure of electrocatalysts, ion exchange enables leveraging strengths and compensating for weaknesses. This review begins with an exploration of the fundamentals of water splitting and ion exchange reactions, stating the regulatory impact of ion exchange on performance. Special emphasis is placed on distinguishing the structural characteristics of different electrocatalysts in the context of ion exchange. The review also underscores the significance of reaction conditions for ion exchange, revealing their dynamic effects. Finally, the review proposes perspectives aimed at inspiring further research efforts to design novel electrocatalysts beyond applying in water splitting. [ABSTRACT FROM AUTHOR]