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To circumvent the issue of halide ion exchange in perovskites, we have decorated CsPbBr3 and CsPbI3 nanocrystals with different sized PbSe nanoparticles and demonstrated that it effectively prevents anion exchange reaction in CsPbBr3/CsPbI3 nanoheterostructures (NHSs) as a consequence of halide vacancy passivation by the more covalent selenide anion. [ABSTRACT FROM AUTHOR]

The development of a new generation of anticorrosion pigments for paints remains an important challenge to replace the usual sparingly-soluble pigments and thus avoid the dissemination of heavy metals in the environment and the formation of holes in polymer coatings. For this purpose, α-zirconium hydrogenophosphate (Zr(HPO4)2·H2O, denoted as α-ZrP) was intercalated with the corrosion inhibitor 2-aminobenzimidazole (ABIM). Various microstructural analyses have proven the insertion of ABIM in the interlayer space by an acid–base exchange reaction and allowed us to propose a structural model for the new ABIM-ZrP pigment. The anticorrosion properties on zinc of the ABIM-ZrP, characterized by electrochemical measurements in 0.1 M NaCl, are due to the release of ABIM molecules by an ion-exchange reaction and the pH-buffer effect of α-ZrP and the amine group of ABIM. Compared to the commercial aluminium tri-phosphate (ATP) pigment, an alkyd-polymer coating loaded with the ABIM-ZrP pigment shows very interesting electrochemical behaviour by avoiding the blistering of the polymer coating and the beginning of zinc corrosion. This effect may be due to both the tortuous effect brought by the platelet shape of the pigments and the release of ABIM once the water uptake of the polymer becomes significant. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co 3 O 4 /RuO 2 heterojunction interface is construct through an ion exchange reaction and pyrolysis. • The optimal Co 3 O 4 /RuO 2 -4 electrocatalyst exhibits outstanding oxygen evolution reaction activity and remarkable stability at large current density. • The electronic structures of Co 3 O 4 /RuO 2 are modulated at the heterointerface which regulating electron redistribution. Exploring effective strategies for developing new high-efficiency catalysts for water splitting is essential for advancing hydrogen energy technology. Herein, Co 3 O 4 /RuO 2 heterojunction interface is construct through ion exchange reaction and pyrolysis. The as-synthesized Co 3 O 4 /RuO 2 -4 exhibits outstanding oxygen evolution reaction (OER) activity at the current density of 100 mA cm−2 with a low overpotential of 276 mV, and remarkable stability (maintaining activity for 60 h at 100 mA cm−2). Experimental results and theoretical calculations reveal that the electrons around the heterogeneous interface transferred from RuO 2 to Co 3 O 4 , resulting in electron redistribution and optimization of energy barriers for OER intermediates. This unique composite catalyst structure offers a new potential for designing efficient oxygen electrocatalysts at large current density. [ABSTRACT FROM AUTHOR]

The thermodynamics and kinetics of interdiffusion are analyzed for the case of glass ion exchange, a process by which alkali ions from a glass inter‐diffuse with different, usually larger, alkali ions from a surrounding salt bath. The spontaneity of the ion exchange reaction is driven by entropy production. This paper details the first derivation and quantification of the entropy produced during this process. We present models for the evolution of the ion concentration profile for both common and extreme conditions, validate against experimental literature, and derive the entropy produced due to ion exchange as a function of time, temperature, composition, diffusivity, and glass and salt bath dimensions. Results reveal that when considering typical industrial parameter sets, the entropy produced in the glass accounts for <10% of the total entropy production, with the entropy produced in the salt bath being the dominant factor driving reaction spontaneity. Using the equations derived in this work, one can calculate concentration profile and entropy production for a two‐ion interdiffusion process between a low‐viscosity liquid and materials including, by not limited to, glass‐forming systems. [ABSTRACT FROM AUTHOR]

The complex formation of the redox-active ligand bis(N,N'-2,6-diisopropylphenyl)-9,10-phenanthrenediimine (DippPDI) with alkaline metal (Li, K) and lanthanide (Sm, Dy) cations is studied. The reduction of DippPDI with an alkaline metal excess affords the dianionic form of the ligand (DippPDA2–), which crystallizes with the potassium cation as the coordination polymer [K2(DippPDA)(Thf)3] (Thf is tetrahydrofuran). The reaction of equimolar amounts of the lithium salt with the dianionic form of the ligand and neutral diimine affords the lithium complex with the radical-anion form (DippPSI•–) crystallized as [Li(DippPSI)(Thf)2]. The samarium(III) complex [SmCp*(DippPDA)(Тhf)] (I) is formed by the reduction of DippPDI with samarocene [Sm (Thf)2] (Cp* is pentamethylcyclopentadienide): both the samarium(II) cation and Cp*– anion are oxidized in the reaction. DippPDI does not react with similar ytterbocene. The dysprosium(III) complexes are synthesized by the ion exchange reactions between DyI3(Thf)3.5 and potassium or lithium salt with the DippPDA2– dianion. Similar complexes [Dy(DippPDA)I(Thf)2] (IIThf) and [Dy(DippPDA)I(Thf)(Et2O)] () are formed in the reactions with the potassium salt depending on the solvent used: a THF–hexane or a diethyl ether–n-hexane mixture, respectively. The coordination of the dysprosium cation by the π system of the conjugated fragment of the NCCN ligand is observed in IIThf, whereas in this coordination is absent. The reaction with Li2(DippPDA) affords the binary complex salt [Li(Тhf)3(Et2O)][DyI2(DippPDA)(Тhf)] (III, crystallization from a THF–Et2O mixture). The crystallization from THF gives the [Li(Тhf)4][DyI2(DippPDA)(Thf)] salt (III') containing the same anion as III. The structures of all new complexes are studied by X-ray diffraction (XRD, CIF files CCDC nos. 2260307–2260313). [ABSTRACT FROM AUTHOR]

SiOC and SiCaMgOC coatings were prepared by sol–gel method from precursors of hydrosilane and the mixture of hydrosilane, calcium acetylacetonate (Ca(acac) 2) and magnesium acetylacetonate (Mg(acac) 2), respectively. Fourier transform infra-red (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis on the coatings revealed that Ca2+and Mg2+ ions can be successfully doped into SiOC coating after aging and annealing in the SiCaMgOC coating. The cytotoxicity and bioactivity of three samples have been detected by MTT assay, cell adhesion and simulated boy fluid (SBF) immersion test. The results suggested that SiCaMgOC coating induced more apatite than that of C/C and SiOC in the comparable soaking process. SiCaMgOC coating demonstrated better biological activity and cellular adherence for its higher surface roughness and ion exchange reaction between Ca2+and Mg2+ ions and protons (H+/H 3 O+) in the SBF solution. [ABSTRACT FROM AUTHOR]

Clay‐engineered barriers might be subjected to soil salinization issues under climate change. A recently emerged desalinization method is achieved by modifying clays using biochar. However, unsaturated soil responses of biochar‐engineered clays in saline environments under drought conditions remain unknown. This study aims to investigate soil shrinkage and water retention characteristics of biochar‐amended kaolin and bentonite under saline conditions. Soil shrinkage and water retention tests were conducted on clays (with and without biochar addition) with various porewater salinity (i.e., 0%–10%). Physiochemical properties (including zeta potential and porewater pH) were measured to interpret particle–fluid interactions. Shrinkage characteristics of kaolin and bentonite exhibited sensitivity and insensitivity to the porewater salinity, respectively. This phenomenon was explained by hydrogen‐sodium ion exchange and deprotonation phenomenon occurring on kaolin and bentonite, respectively. Biochar significantly alleviated the salinity‐induced shrinkage of clays by increasing the shrinkage limit of kaolin and bentonite by 6%–14% and 50%–107%, respectively (p < 0.05). This was attributed to the porous structure and hydrophilic functionality of biochar that immobilized sodium ions through ion exchange and protonation reactions. The air entry value of clays significantly increased with porewater salinity and biochar addition due to the reduction of void ratio and enhanced capillarity, respectively. An empirical equation was proposed to predict the shrinkage limit of clay in various saline conditions. It highlighted that the application of biochar‐engineered clays could contribute to the desalination and the improvement of resistance to shrinkage damage in hydro‐chemical barriers. Core Ideas: Shrinkage characteristics of kaolin were dependent on the porewater salinity.Biochar alleviated the salinity‐induced shrinkage of clays.Biochar immobilizes sodium ions through ion exchange and protonation reactions. [ABSTRACT FROM AUTHOR]

Curcumin (Cur) has been clinically used for rheumatoid arthritis treatment by the means of reactive oxygen species (ROS) scavenging and immune microenvironment regulation. However, this compound has a poor water solubility and moderate antioxidative activity, favoring no further broadened application. Metal complexes of curcumin such as zinc‐curcumin (Zn−Cur) features enhanced water solubilities, while copper‐curcumin (Cu−Cur) shows a higher antioxidant activity but lower solubility than Zn−Cur. Based on their inherent biological properties, this work proposes a nanomedicine‐based ion‐exchange strategy to enhance the efficacy of Cur for rheumatoid arthritis treatment. Copper silicate nanoparticles with hollow mesoporous structure were prepared to load water‐soluble Zn−Cur for constructing a composite nanomedicine, which can degrade in acidic microenvironment of arthritic region, releasing Cu2+ and Zn−Cur. Cu2+ then substitute for Zn2+ in Zn−Cur to form Cu−Cur with a significantly enhanced antioxidative effect, capable of efficiently scavenging ROS in M1 macrophages, promoting their transition to an anti‐inflammatory M2 phenotype. In addition, the silicate released after nanocarrier degradation and the Zn2+ released after ion exchange reaction synergistically promote the biomineralization of osteoblasts. This work provides a new approach for enhancing the antiarthritic effect of Cur via an ion‐exchange strategy. [ABSTRACT FROM AUTHOR]

Curcumin (Cur) has been clinically used for rheumatoid arthritis treatment by the means of reactive oxygen species (ROS) scavenging and immune microenvironment regulation. However, this compound has a poor water solubility and moderate antioxidative activity, favoring no further broadened application. Metal complexes of curcumin such as zinc‐curcumin (Zn−Cur) features enhanced water solubilities, while copper‐curcumin (Cu−Cur) shows a higher antioxidant activity but lower solubility than Zn−Cur. Based on their inherent biological properties, this work proposes a nanomedicine‐based ion‐exchange strategy to enhance the efficacy of Cur for rheumatoid arthritis treatment. Copper silicate nanoparticles with hollow mesoporous structure were prepared to load water‐soluble Zn−Cur for constructing a composite nanomedicine, which can degrade in acidic microenvironment of arthritic region, releasing Cu2+ and Zn−Cur. Cu2+ then substitute for Zn2+ in Zn−Cur to form Cu−Cur with a significantly enhanced antioxidative effect, capable of efficiently scavenging ROS in M1 macrophages, promoting their transition to an anti‐inflammatory M2 phenotype. In addition, the silicate released after nanocarrier degradation and the Zn2+ released after ion exchange reaction synergistically promote the biomineralization of osteoblasts. This work provides a new approach for enhancing the antiarthritic effect of Cur via an ion‐exchange strategy. [ABSTRACT FROM AUTHOR]

Electrocatalysts that perform well at high current densities play a key role in the industrial implementation of electrochemical water splitting. Recently, bimetallic metal-organic frameworks (MOFs) with abundant active sites have become promising catalysts for efficient hydrogen generation. Herein, we designed Fe-modulated NH2-CoFe MOF nanosheet arrays on nickel foam fabricated by a hydrothermal method and cation exchange reaction for highly efficient oxygen evolution reaction (OER). The cation exchange reaction is a simple and facile strategy for preparing bimetallic MOFs, which allows for the tuning of additional metals while maintaining the structure of the monometallic MOF precursor. In particular, the chemical composition and electrochemical performance of an NH2-CoFe MOF were confirmed to be strongly dependent on the valence state of the Fe precursor. The NH2-CoFe MOF exhibited excellent electrochemical performance and durability in alkaline media, and it showed excellent OER activity at high current density in an alkaline electrolyte, requiring a low overpotential of 358 mV at a current density of 200 mA cm-2. The NH2-CoFe MOF also showed excellent stability and durability for 100 h of continuous operation, even at 100 mA cm-2. Furthermore, we confirmed that the NH2-CoFe MOF showed a small overpotential and great stability under real seawater conditions, proving that it is also applicable to seawater electrolysis. This work not only provides an effective strategy for synthesizing bimetallic MOFs, but also shows that the valence state of Fe ions in the cation exchange reaction affects the electrocatalytic performance of the resulting MOFs. [ABSTRACT FROM AUTHOR]

Sodium titanate nanotubes (NaTiNT) were synthesized using the hydrothermal method; subsequently, ion exchange reactions were carried out on the ions of Na+ present in the lamellar spaces of nanotubes by the intercalation of Ga3+ and/or Ce4+ and/or, revealing the presence of phases like: α-GaOOH and CeO2, probably decorating the surface of the nanotubes showing a complex heterostructure. As far as we know, these are the first titanate nanotubes intercalated with these two ions, gallium, and cerium, reported in the literature. Ion exchange processes preserved the original tubular structure of titanate nanotubes with relevant changes in their surface and interlamellar environment. It is known by the researchers that titanate nanotubes have low toxicity and acceptable biocompatibility. Here, we show that the insertion of Ce4+ and/or Ga3+ in titanate nanotubes increased its cytotoxic activity in melanoma cells, indicating that these hybrid nanomaterials are promising in future for health applications. [ABSTRACT FROM AUTHOR]

Binary transition metal sulfides are considered to be a promising material for supercapacitors, possessing richer electrochemically active sites and superior electrochemical performance. Metal–organic frameworks (MOFs) are often used as self-sacrificing templates in the preparation of metal sulfides. Usually, direct sulfidation of MOFs tends to cause collapse of the morphological structure and blockage of the ion transport channels, so that the morphology of the original MOF template can be well preserved by using pyrolysis followed by S2− ion exchange. In this paper, we first prepared NiCo–MOF-74 on nickel foam by an in situ transformation method from layered double hydroxides (LDHs) through a ligand exchange reaction. Then, CoNi2S4 was synthesized in two steps involving the pyrolysis of NiCo–MOF-74 and a subsequent S2− ion exchange reaction. Compared with direct sulfidation, this synthetic strategy can well maintain the rod-like morphology of MOF-74 arrays and prevent structural collapse. The surface of CoNi2S4 has a fine nanosheet structure, which exposes more active sites and shows a high specific capacitance of 7.50 F cm−2 at 2 mA cm−2 and an excellent Coulomb efficiency (96.32%). In addition, the hybrid supercapacitor assembled with activated carbon shows a high energy density of 0.64 mW h cm−2 at a power density of 1.64 mW cm−2 and a high capacitance retention of 88.39% after 5000 cycles. These results indicate that rod-shaped CoNi2S4 can be controllably prepared from MOF-74 involving an exchange reaction and has promising application in high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Our research area is related to the spiropyrazolinium-containingcompounds, which are insufficiently studied compared with pyrazoline-containing compounds. Nitrogen-containing azoniaspiromolecules have also been well studied. In drug design and other areas, they are a priori important structures, since rigid spirocyclic scaffolds with the reduced conformational entropy are able to organize a closely spaced area. Azoniaspirostructures are currently of wide practical interest as ionic liquids, current sources (membranes), structure-directing agents in organocatalysis, and in the synthesis of ordered ceramics. Our goal was the synthesis of 2-aminospiropyrazolilammonium chlorides and hexafluorophosphates. Our methodology is based on the tosylation of β-aminopropioamidoximes with six-membered N-heterocycles (piperidine, morpholine, thiomorpholine, and phenylpiperazine) at the β-position. 2-Aminospiropyrazolilammonium chlorides and hexafluorophosphates were obtained by the reaction of double ion substitution in the reaction of toluenesulfonates of 2-aminospiropyrazolinium compounds with an ethereal solution of HCl in ethanol and with ammonium hexafluorophosphate in ethanol in quantitative yields of 55–97%. The physicochemical characteristics of the synthesized compounds and their IR and NMR spectra are presented. The obtained salts were additionally characterized by the single-crystal XRD analysis. The presence of both axial and equatorial conformations of spirocations in solids was confirmed. 2-Aminospiropyrazolilammonium chlorides and hexafluorophosphates have weak in vitro antimicrobial activity on Gram-positive and Gram-negative bacterial lines. [ABSTRACT FROM AUTHOR]

Astatine and bismuth sorption on several ion exchange resins from nitric acid media has been studied. This work covers commercially available resins Dowex 50 × 4, MP thiol, Dowex 1 × 8, and TEVA. One of the main advantages of using ion exchangers for astatine separation and purification is the absence of any organic media in the effluent in comparison with extraction chromatography resins. The behavior of the above-mentioned metals was investigated in up to 4 M HNO3 solutions. The determined distribution coefficients are greater than 1 for all the resins studied, reaching 104 for MP thiol and TEVA resins. The interaction of nitric acid with an anion exchanger in Cl-form results in an exchange reaction, where AtO+ chloro complexes can form. To understand the astatine behavior under these conditions, stability constants of AtOCl and AtOCl2− complexes have been reevaluated and discrepancy in the literature values has been eliminated. For each resin a thermodynamic model has been developed to suggest a possible mechanism of astatine sorption. Literature and new experimental data on bismuth sorption by studying resins in nitric acid media have been reviewed and a mathematical model to describe its behavior has been suggested. A ratio of corresponding fit functions of At and Bi assigned to the same resin and acidity has been used to estimate the separation factors of these elements. [ABSTRACT FROM AUTHOR]

The adsorption and direct calorimetric studies of the binary exchange of Ca2+ and Sr2+ cations on the Na-form of low-silica type natural clinoptilolite (Sokyrnytsya, Ukraine) were performed. The ion exchange of Ca2+ and Sr2+ cations on the Na-form of natural clinoptilolite was studied under static conditions at a solid to liquid phase ratio of 1 : 100 and a constant ionic strength of the solution of 0.1. The integral heats of ion exchange for these systems were measured using a highly sensitive Tian-Calve microcalorimeter in a special lab-made cell. Also, the ion exchange isotherms and Kielland curves were plotted, and the corrected selectivity coefficients and ion exchange constants were calculated. Changes in the integrated Gibbs free energies, enthalpies, and entropies of the ion exchange of Ca2+ and Sr2+ cations on the Na-form of clinoptilolite were calculated in entire range of the substitutions of the exchange complex. The thermodynamic parameters of incomplete ion exchange were analyzed in terms of the crystal structure of the zeolite. In addition, the state of exchangeable cations in the channels of clinoptilolite was described in detail. It is shown that structural heterogeneities of cation-substituted forms of clinoptilolite are clearly reflected in the dependence of thermodynamic functions on the degree of exchange, and significant differences are observed between the exchange of Ca2+ and Sr2+ cations that could not be described by standard thermodynamic values. Although the isotherms of ion exchange have a convex shape, the Na-form of clinoptilolite does not show any thermodynamic affinity to Ca2+ cations. This ion exchange reaction is accompanied by positive enthalpy changes in all range of substitutions of the exchange complex. At the same time, thermodynamic selectivity toward Sr2+ cations was observed for 40 % of the zeolite exchange centers, and the exchange is accompanied by minor exothermic effects in the range of small substitutions, and the ion exchange isotherm has σ-like form. In general, the thermodynamic affinity of the Na-form of clinoptilolite to the studied metal ions under conditions of incomplete exchange is ordered as following hydration energy trends in the case of the lyotropic properties among alkaline earth metals. Thus, the experimental thermodynamic characteristics of ion exchange equilibria could be a reliable support for the practical using of natural clinoptilolite. [ABSTRACT FROM AUTHOR]

The effect of the zeolite framework composition on the selectivity and thermodynamic parameters of ion exchange is studied for the exchange reaction of Ca2+ cations on Na-forms of clinoptilolites from nine deposits of Central and Southeast Europe, Northeast Asia, and North America. An increase in the thermodynamic affinity of Na-forms towards Ca2+ cations is shown with a decrease in the Si/Al ratio in their zeolite framework. [ABSTRACT FROM AUTHOR]

Great efforts have been made to develop the fabrication of zinc-based ternary metal oxides used in lithium-ion batteries due to their excellent properties of good electrochemical activities, stable chemical structures, and high specific capacities in recent decades. Here, we reviewed the synthetic methods of zinc-based ternary metal oxides and their application in high-performance lithium-ion batteries, including effects of synthesis factors on morphologies and electrochemical properties of the materials. Meanwhile, various electrochemical and physical characterization techniques were used to characterize the Li-storage electrochemical processes of electrodes. Metal ion exchange methods, as popular and convenient synthesis ways, were used to synthesize zinc-based ternary metal oxides based on readily synthesized metal compounds as templates and metal ion sources by liquid phase cation exchange in the last decade. We key described the alcohol solvothermal zinc ion exchange reaction process and discussed effects of Zn/Ti mole ratios on structures and Li-storage electrochemical performance of the materials. Accordingly, we also predicted on the future development prospects of zinc-based ternary metal oxides. [ABSTRACT FROM AUTHOR]

We present geochemical and mineralogical datasets for five new mud volcanoes in continental Azerbaijan (Hamamdagh and Bendovan) and the adjacent Caspian Sea (Khara-Zire, Garasu and Sangi-Mughan). The fluid ejects have a Na–Cl-type composition and are generated by the mixing of evaporated Caspian seawater and low- to high-salinity pore waters, as indicated by Br–B and Cl–B systematics and Na–K and SiO2 geo-thermometers. The fluids contain high concentrations of As, Ba, Cu, Si, Li, Sr and Zn (60 to 26,300 ppm), which are caused by surface evaporation, pyrite oxidation, ion exchange reactions and hydrocarbon maturation in Oligocene-Miocene 'Maykop' shales. The solid ejects comprise liquid, oily and brecciated mud, mud/claystones and sandstones. The mud heterogeneity of the volcanoes is related to the geological age and different sedimentological strata of the host rocks that the mud volcanoes pass through during their ascent. All ejects show evidence of chemical alterations via water–rock–gas reactions, such as feldspar weathering, smectite illitization and the precipitation of Fe-(hydr)oxides, calcite, calcian dolomite, kaolinite and smectite. The studied localities have petrographic similarities to northern extending mud volcano systems located on Bahar and Zenbil islands, which suggests that mud volcanoes in the Caspian Sea region are sourced from giant shallow mud chambers (~1–4 km depth) located in Productive Series strata. Our results document the complex architecture of the South Caspian Basin—the most prolific hydrocarbon region in the world. [ABSTRACT FROM AUTHOR]

Cobalt-based spinel oxides are considered potential candidates for the oxygen evolution reaction (OER) due to their abundant valence changes and promising electrochemical activity, but their low intrinsic activity hinders their practical applications. Herein, we synthesize a series of CoCeMOx (M = Zn, Ni, Ru, Er, Mg, Mn, Sn) derived from CoCeM coordination-driven self-assembled aggregates (CDSAAs) using a general ion exchange and subsequent calcination method. Interestingly, CoCeMOx exhibit different morphologies from porous nanospheres, particle-stacked nanospheres, to hollow nanospheres as the third metal element is altered. Markedly, CoCeZnOx porous nanospheres (PNs) exhibit the best OER performance. The XPS results reveal that the existence of CeO2 and Zn2+ ions significantly increased the Co2+/Co3+ ratio and the content of oxygen vacancies in Co3O4. Furthermore, Co2+ can be used as highly reactive sites to form CoOOH and the high content of oxygen vacancies can optimize the oxygen-containing intermediate adsorption energy, both of which can effectively improve the OER performance. Therefore, well-designed CoCeZnOx PNs demonstrate high OER activity with a lower overpotential (η = 333 mV) than that of commercial RuO2 (344 mV) in 10 mA cm−2, a Tafel slope of 98 mV dec−1, and a long-term durability of 45 h. This work may provide some inspiration for the design of trimetallic oxide nanomaterials. [ABSTRACT FROM AUTHOR]

We present an enhanced method for synthesizing sheets of borophane. Despite the challenges associated with low efficiency, we discovered that incorporating hydrochloric acid into the ion-exchange reaction significantly improved the production yield from 20% to over 50%. After a thorough examination of the reaction, we gained insight into the underlying mechanisms and found that the use of hydrochloric acid provides two key benefits: accelerated production of borophene and isolation of high-purity products. This method has the potential to pave the way for the production of novel topological 2D materials with potential industrial applications. [ABSTRACT FROM AUTHOR]

Titanate nanotubes were synthesized and subjected to an ion exchange reaction with erbium salt aqueous solution to obtain titanate nanotubes exchanged with erbium (3+) ions. In order to evaluate the effects of the thermal treatment atmosphere on the structural and optical properties of erbium titanate nanotubes, we subjected them to heat treatment in air and argon atmospheres. For comparison, titanate nanotubes were also treated in the same conditions. A complete structural and optical characterizations of the samples was performed. The characterizations evidenced the preservation of the morphology with the presence of phases of erbium oxides decorating the surface of the nanotubes. Variations in the dimensions of the samples (diameter and interlamellar space) were promoted by the replacement of Na+ by Er3+ and the thermal treatment in different atmospheres. In addition, the optical properties were investigated by UV–Vis absorption spectroscopy and photoluminescence spectroscopy. The results revealed that the band gap of the samples depends on the variation of diameter and sodium content caused by ion exchange and thermal treatment. Furthermore, the luminescence strongly depended on vacancies, evidenced mainly by the calcined erbium titanate nanotubes in argon atmosphere. The presence of these vacancies was confirmed by the determination of Urbach energy. The results suggest the use of thermal treated erbium titanate nanotubes in argon atmosphere in optoelectronics and photonics applications, such as photoluminescent devices, displays, and lasers. [ABSTRACT FROM AUTHOR]

A constructed wetland (CW)-coupled microbial fuel cell (MFC) system was constructed to treat wastewater and generate electricity. The total phosphorus in the simulated domestic sewage was used as the treatment target, and the optimal phosphorus removal effect and electricity generation were determined by comparing the changes in substrates, hydraulic retention times, and microorganisms. The mechanism underlying phosphorus removal was also analyzed. By using magnesia and garnet as substrates, the best removal efficiencies of two CW-MFC systems reached 80.3% and 92.4%. Phosphorus removal by the garnet matrix mainly depends on a complex adsorption process, whereas the magnesia system relies on ion exchange reactions. The maximum output voltage and stabilization voltage of the garnet system were higher than those of the magnesia system. Microorganisms in the wetland sediments and electrode also changed considerably. It indicates that the mechanism of phosphorus removal by the substrate in the CW-MFC system is adsorption and chemical reaction between ions to generate precipitation. The population structure of proteobacteria and other microorganisms has an impact on both power generation and phosphorus removal. Combining the advantages of constructed wetlands and microbial fuel cells also improved phosphorus removal in coupled system. Therefore, when studying a CW-MFC system, the selection of electrode materials, matrix, and system structure should be taken into account to find a method that will improve the power generation capacity of the system and remove phosphorus. [ABSTRACT FROM AUTHOR]

The cation exchange selectivity in the Na-montmorillonite interlayer has been extensively studied as a part of the mechanism of the cation exchange reaction, which also provides an important insight into the inhibition of montmorillonite expansion by inorganic salts. While the variation of interlayer structure associated with interlayer Na+ and water molecules during the ion exchange process has less been explored, to determine the possibility of replacing interlayer Na+ ions by the ion exchange reaction, the present study focuses on the effects of the added electrolyte cation (Mg2+, Ca2+ and K+) on the structure properties, diffusion features and the number of surface hydrogen bonds in hydrated Na-montmorillonite at different hydration stages by using molecular dynamic (MD) simulations. The simulation results showed that Ca2+ has a better tendency to exchange Na+ ions at a high hydration degree, and K+ is easier to exchange Na+ at a low hydration degree. The lower mobility of interlayer species and the relativity large change in the number of hydrogen bonds with the addition of Mg2+ reflected its weak possibility of exchanging Na+ . [ABSTRACT FROM AUTHOR]

Kinetic parameters have been estimated for the H2–D2 exchange reaction on a thin film Pd catalyst by fitting reaction data from T = 333 to 593 K over a range of inlet partial pressures, P H 2 in and P D 2 in . A rigorous approach to estimating the 95% confidence regions of the kinetic parameters reveals some of the issues and complexities that are not routinely considered in the estimation of kinetic parameter uncertainty from catalytic data. Three different mechanistic models were used to assess the influence of subsurface hydrogen, H′: the traditional Langmuir–Hinshelwood (LH) mechanism, the Single Subsurface Hydrogen (1H′) mechanism, and the Dual Subsurface Hydrogen (2H′) mechanism. The fitting was performed by fixing the pre-exponential factors for all Arrhenius rate constants and equilibrium constants to their transition state theory values. The diffusion of H and D atoms from the surface into the subsurface was constrained to be endothermic (i.e. Δ E ss > 0) and represented as an equilibrium process. Performance of the fitting routine was evaluated on a noiseless simulated dataset (created using Δ E ads ‡ = 0, Δ E des ‡ = 43, and Δ E ss = 25 kJ/mol) and the same simulated dataset with the inclusion of 3% Gaussian noise. In both cases, the solver was able to return the chosen values of Δ E ads ‡ , Δ E des ‡ , and Δ E ss . Mapping of the behavior of the residual sum of squared errors, χ 2 , about its global minimum within 3D ( ϵ ads , ϵ des , ϵ ss ) parameter space allowed quantification and visualization of the 95% confidence regions using 2D error ellipses for each pair of fitting parameters. For the experimental dataset on the Pd catalyst, fitting to the LH model predicted that H2–D2 exchange is adsorption rate limited, with Δ E ads ‡ = 51.1 ± 0.6 kJ/mol with 95% confidence. On the other hand, fitting to both the 1H′ and 2H′ models led to predictions of Δ E ads ‡ = 0, consistent with the current understanding that the barrier to H2 dissociation on Pd is low. Thus, the results detailed herein provide supporting evidence for a non-LH mechanism for H2–D2 exchange on Pd while also illustrating the issues associated with quantification of uncertainty in kinetic parameter estimation. [ABSTRACT FROM AUTHOR]

Agarose-vinyl sulfone (VS) beads have proven to be a good support to immobilize several enzymes. However, some enzymes are hardly immobilized on it. This is the case of penicillin G acylase (PGA) from Escherichia coli, which is immobilized very slowly on this support (less than 10% in 24 h). This enzyme is also not significantly adsorbed in aminated MANAE-agarose beads, an anionic exchanger. In this study, MANAE-agarose beads were modified with divinyl sulfone (DVS) to produce MANAE-vinyl sulfone (VS) agarose beads. When PGA was immobilized on this support, the enzyme was fully immobilized in less than 1.5 h. PGA cannot be released from the support by incubation at high ionic strength, suggesting that the enzyme was rapidly immobilized in a covalent fashion. Considering that the amount of reactive VS groups was only marginally increased, the results indicated some cooperative effect between the anion exchange on the amine groups of the support, probably as the first step of the process, and the covalent attachment of the previously adsorbed PGA molecules. The covalent reaction of the previously adsorbed enzyme molecules proceeds much more efficiently than that of the free enzyme, due to the proximity of the reactive groups of the support and the enzyme. Finally, the steps of immobilization, incubation, and blocking with different agents were studied to determine the effects on final activity/stability. The stability of PGA immobilized on this new catalyst was improved with respect to the VS-agarose prepared at low ionic strength. [ABSTRACT FROM AUTHOR]

M−N−C electrocatalysts are considered pivotal to replace expensive precious group metal‐based materials in electrocatalytic conversions. However, their development is hampered by the limited availability of methods for the evaluation of the intrinsic activity of different active sites, like pyrrolic FeN4 sites within Fe−N−Cs. Currently, new synthetic procedures based on active‐site imprinting followed by an ion exchange reaction, e.g. Zn‐to‐Fe, are producing single‐site M−N−Cs with outstanding activity. Based on the same replacement principle, we employed a conservative iron extraction to partially remove the Fe ions from the N4 cavities in Fe−N−Cs. Having catalysts with the same morphological properties and Fe ligation that differ solely in Fe content allows for the facile determination of the decrease in density of active sites and their turn‐over frequency. In this way, insight into the specific activity of M−N−Cs is obtained and for single‐site catalysts the intrinsic activity of the site is accessible. This new approach surpasses limitations of methods that rely on probe molecules and, together with those techniques, offers a novel tool to unfold the complexity of Fe−N−C catalyst and M−N−Cs in general. [ABSTRACT FROM AUTHOR]

The basic principle of in situ leaching is chemical mining. The process of in situ leaching is to inject leaching solution into the ore body, and the leaching solution is spread in the pores of the mountain. The process is completed by the coupling action of the liquid seepage field and ion exchange reactions. In the production process, only one injection of liquid can be carried out in a certain stope, so it is impossible to improve the injection process and leaching effect through field practice. By simulating the in situ leaching process of rare earth ions, this paper builds the test stope true three-dimensional numerical model and simulates the leaching process of rare earth ore under the coupling of seepage control, ion exchange, and dilute material transfer in porous media. The migration rule of RE3+ and Mg2+ in stopes was analyzed to evaluate the leaching effect. It is of great significance to increase the recovery rate of rare earth ore. [ABSTRACT FROM AUTHOR]

[NEt3Me][O3] was obtained for the first time by an ion exchange reaction in liquid ammonia. It was thoroughly characterized by X‐Ray diffraction [P21; a=598.51(4) pm, b=1032.03(7) pm, c=723.83(6) pm, β=92.677(3)°, R=0.0384, 15070 reflections] applying non‐spherical and spherical atomic form factors for the refinements. In contrast to previous reported ozonides, [NEt3Me][O3] is the first to adopt the tungsten carbide (WC) motif of cation/ anion arragemnent and shows an untypical hydrogen bond between the central oxygen atom of the ozonide and the cation. Additionally, IR spectroscopy as well as quantum‐chemical calculations were applied to further characterize the compound. The obtained ozonide showed high solubility in ammonia as well as acetonitrile and good properties as a synthon in ozonide chemistry. [ABSTRACT FROM AUTHOR]

The exchange reaction of cadmium by non‐toxic metallic cation ions in a cadmium‐containing apatite was studied. A cadmium‐containing apatite with characteristics close to those of natural phosphate ore was synthesized. Copper and then zinc ions have been found to be the most effective elements for the exchange reaction. After 4 h of treatment at room temperature, 25 % and 14 % of cadmium were removed using 0.1 m solutions of copper and zinc ions, respectively. At 60 °C, cadmium removal efficiency improved considerably. For copper ions, the efficiency reached 53 %, while it arrived at 25 % for zinc ions. The equilibrium study shows that the two reactions are thermodynamically feasible but balanced reactions with little reaction progress for small cadmium content. The reaction can be well modeled by the shrinking‐core model and is found to be controlled by the diffusion through the reacted layer. [ABSTRACT FROM AUTHOR]

Efficient inverted (pâ€"iâ€"n) type CsPbI3 perovskite solar cells (PSCs) have revealed promising applications due to their excellent thermal and photostability. Regulating the nucleation and crystallization of perovskite film is an important route to improving the performance of CsPbI3 PSCs. Herein, we explored cesium acetate (CsAc) as additive to manipulate the crystallization process of CsPbI3 perovskite films. By involving in the intermediate phase DMA1- x Cs x PbI3- y Ac y of perovskite, the pseudo-halide acetate (Acâˆ') can retard the ion exchange reaction between DMA+ and Cs+, leading to a perovskite with dense morphology, low defect density, and a long carrier lifetime. As a result, the optimal CsPbI3 PSCs yielded a high power conversion efficiency of 18.3%. Moreover, the encapsulated devices showed excellent operational stability and the devices retained their initial performance following 500 h of operation at the maximum power point under one-sun illumination in ambient conditions. [ABSTRACT FROM AUTHOR]

We report, for the first time, the preparation and ionic conductivity of a Mg2+-containing metal–organic framework (MOF) having type A features, i.e., an anionic framework containing Mg2+ as the counter cation. We prepared Mg3[(MnMo6O18)2L] (L12− = C{C6H4CH＝NC(CH2O)3}412−) (MOF-688-Mg) through a simple ion exchange reaction, and it showed high ionic conductivity above 10−5 S cm−1 at 25 °C under MeCN vapor. [ABSTRACT FROM AUTHOR]

The paper considers the basic principles of organizing the isotope separation process for alkaline elements in a countercurrent of the two-phase ion-exchange system with electrochemical conversion of phase flows under the conditions of electromigration of isotopically substituted ion forms during electrodialysis. Mathematical models of the process of isotopic enrichment have been developed that take into account the electrochemical method of phase flow reversal with the flow moving in a column of an ion exchanger. The conditions for the transport of isotopic ions in vertical and horizontal directions have been established together with the time of diffusion of isotopically substituted ion forms through the working chamber of an electrodialysis apparatus operating under dynamic conditions of solution supply, energy consumption, and power supply. The results of theoretical research for two-phase exchange systems with subsequent electroregeneration of ion-exchange material are in good agreement with the available experimental data. [ABSTRACT FROM AUTHOR]

In this work, Layered Double Hydroxide (LDH) materials carrying the worldwide administered non-steroidal anti-inflammatory drug naproxen (NAP), and the sodium naproxenate salt (NaNAP) for comparison, were studied by computational approaches aiming to model the structure of hybrid LDH-drug and shed light on NAP intercalation process. Atomic modeling calculations were performed at the quantum mechanical level based on Density Functional Theory and classical force fields based on empirical interatomic potentials. LDH NAP materials were prepared by ion exchange reaction from Mg 2 Al(OH) 6 Cl and Zn 2 Al(OH) 6 Cl pristine phases. The characterization of the materials confirmed NAP intercalation and also the permanence of the pristine phases in the isolated materials after ion exchange. Crystallographic lattice parameters, elemental analysis, and TGA experimental results were then employed in the calculations, which revealed that NAP anions can completely neutralize the positive charge of the LDH layers: both Mg 2 Al and Zn 2 Al LDH structures could be optimized with all Cl− anions substituted by NAP. The drug assumed different dispositions in the NaNAP crystal or when intercalated into LDH. Additionally, infrared wavenumbers calculations agreed with the experimental results and showed useful to support LDH NAP bands assignment. The employed theoretical models to represent the structure of LDH NAP systems are expected to assist the interpretation of future experimental results and to be used as auxiliary tools to tune properties of LDH-drug pharmaceutical formulations. [Display omitted] • Density functional theory and classical force fields based on empirical interatomic potentials were applied for the Mg 2 Al-NAP and Zn 2 Al-NAP LDH materials. • The crystal structure of the NaNAP was optimized and the main IR wavenumbers were calculated and agreed with the experimental results. • Calculations showed that the charge of the LDH layers can be completely neutralized by NAP, thus achieving maximum ion exchange capacity. • NAP assumed different dispositions in the NaNAP crystal or intercalated into LDH. [ABSTRACT FROM AUTHOR]

Scorodites are commonly used for arsenic immobilization, and it is also the main component of arsenic bearing tailings. Alkali-activated geopolymers are commonly used to landfill arsenic-bearing minerals. However, there no previous studies have explored the interaction between geopolymer molecules and the surface of scorodite. In this paper, Si(OH) 4 as a monomer molecule of geopolymer, the mechanism of adsorption and 'ion exchange' between Si(OH) 4 molecule and the surface of scorodite during alkali-activation is studied. Results show that the Fe-terminated scorodite (010) surface has high stability. Si(OH) 4 are more easily adsorbed on the hollow site of an Fe-terminated scorodite (010) surface, which is described as chemisorption. Compared with Si(OH) 4 , NaOH is easier to adsorb on an Fe-terminated scorodite (010) surface. The co-adsorption of NaOH and Si(OH) 4 on the Fe-terminated scorodite (010) surface was studied, and also belongs to chemical adsorption. When the hydroxyl binds to the As atom, the adsorbed Si(OH) 4 is more likely to undergo an 'ion exchange' reaction with the surface, and the reaction is barrierless. The intermediate As(OH) 4 produced by the 'ion exchange' reaction can be deprotonated to form an arsenate molecule, which can occur spontaneously. This work reveals that the interaction mechanism of geopolymer molecules on surface of scorodite. [Display omitted] • The stability of different surfaces of scorodites was studied. • The adsorption of geopolymer Si(OH) 4 molecules and NaOH on the surface was studied, and the co-adsorption of the two was studied. • The replacement reaction between the surface adsorbed molecules and the surface atoms was studied. • The ion exchange reaction between the coating material and the scorodites was demonstrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel isotherm model for the thermodynamic study of ion exchange reactions is proposed. • The results calculated by the novel isotherm model agree well with the experimental data. • The physical meaning of the parameters involved in the novel isotherm model is clear. • It is applicable to various situations of ion exchange reactions and has good versatility. Ion exchange is a separation and purification technique widely employed in chemistry, environment and metallurgy. Commonly, the isotherm models used for thermodynamic study are the Langmuir model and the Freundlich model. However, these two models are initially used to study the adsorption of gas molecules onto solids, and there are some limitations if they are applied to ion exchange reactions. In this paper, a novel isotherm model (NIM) for ion exchange reactions was derived based on the process of ion exchange, the principle of electroneutrality and the law of conservation of mass. The NIM was utilized to study the reactions of anions (F-, WO 4 2 - , MoO 4 2 - , PO 4 3 - , AsO 4 3 - , MoS 2 O 2 2 - , MoS 4 2 - ) with chloride-form strongly basic anion exchange resins. Moreover, the reactions of cations (K+, Ca2+) with sodium-form cation exchange resins were also explored. The results indicated that the calculation data based on the NIM matched up well with the experiments, even though the ions have various valences and different affinities for the resin, which proved the reliability of the model. In addition, the compatibility of the NIM with the Langmuir and Freundlich models was theoretically analyzed, and the conclusions were also verified by the experimental data. By contrast, the physical meaning of the parameters involved in the NIM was clear and had a good generality, which can be applicable to various situations of ion exchange reactions. Therefore, the NIM proposed in this work can effectively obtain the thermodynamic parameters of ion exchange reactions, and is expected to provide theoretical basis for the design, optimization and control of ion exchange processes. [ABSTRACT FROM AUTHOR]

[Display omitted] Crystalline hydrates of swelling clay minerals (smectites) exhibit a strong coupling between their ion exchange and hydration/dehydration reactions. The uptake or removal of water from smectite interlayers as a result of a change in the environmental conditions also leads to the partitioning of cations. Three factors, the solid ion composition, the solid basal spacing/water content, and the aqueous solution composition, are all implicated in controlling the thermodynamics of ion exchange. However, conventional approaches to measuring the exchange free energy cannot separate the influence of each of these individual factors. Here, we explore the energetics of the swelling and ion exchange reactions in montmorillonite using a potential of mean force approach and the thermodynamic integration method within molecular simulations. We investigate the influence of solution and clay composition on the spontaneity of the reactions, focusing on the 2 water-layer hydration state. The swelling simulations provide the equilibrium water content, interlayer water structure, and basal spacings, while thermodynamic integration of sodium–potassium exchange in the aqueous solution and solid phase are combined to calculate ion exchange free energies as a function of solution composition. Results confirm the tendency of the clay to collapse to lower hydration states as the concentration of the solution increases. Changes to the equilibrium water content, even at fixed hydration states, and the composition of the mixed electrolyte solution play a critical role in driving ion exchange and the selectivities of the clay to the exchanged cation, while the composition of the solid phase is shown to be insignificant. These findings underscore the extreme sensitivity of clay swelling and ion exchange thermodynamics to small (tenths of an Angstrom) deviations in layer spacing. [ABSTRACT FROM AUTHOR]

Peroxides in edible oils, whose amounts are measured using the peroxide value, are closely related to human health. Long-term consumption of edible oils with high peroxide values can lead to a variety of human diseases, which highlights the significance of examining oil types and their corresponding peroxide values. For identifying a wide range of edible oils, we established a colorimetric sensor array based on the halogen ion exchange between CsPbBr3 and two iodides (octadecylammonium iodide (ODAI) and ZnI2). Different kinds of edible oils contain distinct peroxidic substances that have the distinct ability to oxidize iodides. After specific types of edible oils react with excess iodides (ODAI and ZnI2), different amounts of residual iodides are left for further halogen exchange with CsPbBr3, resulting in various colorimetric responses, measured in RGB (red/green/blue) values, under fluorescent light. Based on RGB pattern analysis as fingerprints using two anion exchangers (ODAI and ZnI2), our proposed colorimetric sensor array was proved by linear discriminant analysis (LDA) to have an ability to accurately distinguish edible oils at a minimal volumetric concentration of 6.67% in seven real samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple synthesis method has been developed for Ag@ZIF-8, involving controlling the loading and size of Ag NPs. • Ag@ZIF-8 meet the requirements for antibacterial agent used in the melamine-impregnated paper. • The multiple synergistic antibacterial mechanism of Ag@ZIF-8 was verified. • The decorated blockboards with 0.20 wt% Ag@ZIF-8 reached Level Ⅰ antibacterial grade. Melamine-impregnated paper, a decorative material in furniture and interior design, could potentially impede the spread of indoor bacteria if it possesses antibacterial properties. Here, nano Ag-doped ZIF-8 (Ag@ZIF-8) was synthesized using ion exchange and in-situ chemical reduction strategies, followed by incorporating it into melamine-impregnated paper. The ion exchange mechanism of Zn2+ and Ag+ during ion exchange reactions was investigated. The structure of Ag@ZIF-8 was well-defined, with Ag nanoparticles evenly distributed on the surface of ZIF-8. Ag@ZIF-8 showed good thermal stability at 400 °C, meeting the requirements for the hot-pressing process of the melamine-impregnated paper. Ag@ZIF-8 exhibited enhanced ROS generation under visible light compare to ZIF-8, which was attributed to its reinforced light absorption and charge carrier separation facilitated by the localized surface plasmon resonance (LSPR) effect. The antibacterial activity of Ag@ZIF-8 was better than ZIF-8, owing to the multiple-synergistic antibacterial mechanisms of the ion release and ROS generation. Specifically, the 10-Ag@ZIF-8 exhibited MIC of 128 μg/mL and 64 μg/mL against E. coli and S. aureus , respectively. The signal intensity of •O 2 − induced by 10-Ag@ZIF-8 was 4.38 times higher than that of ZIF-8. As the addition of Ag@ZIF-8 increased, the antibacterial performance of melamine-impregnated paper improved. Considering the antibacterial property and economy of melamine-impregnated paper, 0.20 wt% was the optimal amount for 10-Ag@ZIF-8 decorated blockboard. This study proposes a novel approach for synthesizing MOF-based melamine-impregnated paper with antibacterial properties, aiming to reduce bacterial spread, minimize disease risks, and contribute to lowering overall healthcare costs. [ABSTRACT FROM AUTHOR]

Structural modeling and adsorption mechanism of Li+ on Zr-doped adsorbent. [Display omitted] Lithium-titanium-zirconium composite oxide Li 4 Ti 4.98 Zr 0.02 O 12 (hereinafter referred to as LZrTO) was successfully prepared by a solvothermal method. The structure and morphology of the LZrTO sample were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The LZrTO samples washed by 0.1 mol/L HCl aqueous solution were converted into lithium-ion sieve H 4 Ti 4.98 Zr 0.02 O 12 (hereinafter referred to as HZrTO). The saturated ion exchange capacity and selectivity, pH titration curves, kinetic parameters, and equilibrium coefficients of the Li+-H+ ion exchange reaction were determined. SEM results showed that the LZrTO samples presented a spherical structure with a diameter of 3 ∼ 6 μm and a porous surface. The saturated exchange capacity of the lithium-ion sieve HZrTO for Li+ was up to 6.99 mmol g−1 and remained at 6.76 mmol g−1 after five cyclic exchange tests. In a mixed solution of Li+, Na+, K+, Mg2+, and Ca2+, the selectivity of Li+ ion exchange by HZrTO was 6.23 mmol g−1, which was higher than that of Na+, K+, Mg2+, and Ca2+. The relationship between adsorption time and adsorption capacity of HZrTO was investigated using pseudo-first-order and pseudo-second-order kinetic models, and the adsorption behavior of Li+ on the ion sieve HZrTO was characterized using Langmuir and Freundlich isotherm equations. The results of kinetic experiments verified that the adsorption behavior of Li+ on HZrTO is chemisorption and monolayer adsorption. [ABSTRACT FROM AUTHOR]

A photoelectrochemical (PEC) sensor driven by visible light has been developed to detect Hg2+ with a signal output "turn-on" mode on basic of the double ZIF-Cds@Zns@HgS type-II heterojunction formed by a target-triggered double-ion exchange reaction. The type-II heterojunction photocatalysts ZIF-CdS@ZnS were prepared through growing ZnS nanoparticles onto ZIF-CdS hollow nanocages which were innovatively synthesized using ZIF-67 as a template by MOF-engaged directional deposition strategy. An obvious photocurrent amplification effect induced by mercury ions is evident in ZIF-CdS@ZnS modified ITO electrodes, compared to ZIF-CdS or pure ZnS modified electrodes. The ZIF-CdS@ZnS heterojunction would successfully utilize visible light to promote the photoelectric response process due to the synergistic effect of the narrow band gap component and cavity structure. More importantly, the photocurrent can be greatly amplified by the target-triggered double-ion exchange reaction, which results in the generation of double type-II heterostructures HgS@ZnS@CdS, where an electrical field resulting from the unification of the fermi level facilitates the separation of photogenerated charges and increases the output photocurrent. Besides, the target-triggered double ion exchange strategy can provide guidance for the design of signal-on PEC sensors to detect other heavy metal ions sensitively. • PEC sensor realized the detection of Hg2+ with "signal on" model under visible light. • A double-ion exchange strategy was used to selectively capture target of Hg2+ more efficiently. • Double type-II heterostructure in-situ growth could be triggered by Hg2+. • Photocatalyst has a higher photon capture efficiency due to cavity multiple reflection. [ABSTRACT FROM AUTHOR]

Metal ion doping is an effective strategy for enhancing the photoelectric properties of quantum dots (QDs). In this study, Zn-doped CdSSe composite QDs (ZnCdSSe) were synthesized using a two-step hydrothermal ion exchange method. The synthesis process involved the exchange reaction of Cd2+ with Zn2+, followed by the exchange reaction of Se2− with S2−, based on ZnS templates. The morphology, composition and crystalline phase of synthesized QDs were characterized using X-ray and electron-based techniques such as XRD, SEM, TEM, and XPS. The results indicate ZnCdSSe QDs were synthesized while preserving a similar morphology to that of ZnCdS. Performance tests demonstrated that quantum dot sensitized solar cells (QDSSCs) equipped with ZnCdSSe/TiO 2 photoanodes achieved a power conversion efficiency (PCE) of 3.61% by optimizing the hydrothermal reaction temperature and time. This efficiency was 33.2% higher than that of CdSSe (2.17%) QDSSCs synthesized via a one-step hydrothermal exchange reaction using CdS templates. The significant enhancement in PCE can be attributed to improvements in light absorption and charge carrier transport. Notably, Zn doping reduced interface charge recombination and prolong electronic lifetime (τ n), facilitating more effective charge collection in QDSSCs. A schematic diagram depicting the synthesis of ZnCdSSe quantum dots through a two-step hydrothermal ion exchange method. This process includes the interchange of Cd2+ and Zn2+, then the substitution of Se2− with S2−, utilizing ZnS templates. [Display omitted] • Zn-doped CdSSe QDSSCs are fabricated using a two-step ion exchange method. • The favorable crystal structure of ZnCdSSe QDs resulted in high light absorption. • Zn doping reduced interface charge recombination and extended the electronic lifetime. [ABSTRACT FROM AUTHOR]

• The adsorption of Pb(II) by D001 resin in high gravity was first explored. • High gravity-ion exchange coupling enhances Pb(II) adsorption by D001. • More Pb(II) are adsorbed in RPB than in TS and STR. • Pb(II) are adsorbed by ion exchange reactions with R-SO 3 Na of D001. The treatment of Pb(II) is a challenging problem. In this study, a new approach for removal of Pb(II) using D001 resin in a rotating packed bed (RPB) is proposed, and the adsorption behaviors and mechanisms are investigated. The results reveal that under optimal conditions (initial Pb(II) concentration c 0 = 100 mg L−1, high-gravity factor β = 36.33, liquid flow rate Q L = 60 L h−1, initial solution pH = 5.0, and temperature T = 303 K), the removal rate of Pb(II) in RPB is 95.54 % at 120 min, which is 12.18 % and 9.81 % higher than that in thermostatic shaker (TS) and stirred tank reactor (STR). The adsorption of Pb(II) by D001 resin can be well described by the Langmuir adsorption isotherm and the adsorption heat is 13.24 kJ mol−1, and it is a typical monomolecular layer adsorption. It is also found that the adsorption mechanism of Pb(II) by D001 resin in RPB follows the pseudo-first-order kinetics, and the rate constant k 1 is 1.72 and 1.64 times that in TS and STR. The R-SO 3 Na is the dominant group and Na+ undergoes ion exchange with Pb (II) on the surface of D001 resin. This study provides a new method for the treatment of Pb(II). [Display omitted] [ABSTRACT FROM AUTHOR]

A novel Egeria najas driven-biochar was activated by loading ferric chloride onto surface (FeCl 3 @EN-BC). The synthesized composite was evaluated for its physicochemical properties and Cr(VI) adsorption behavior and mechanism. The result of SEM showed that the modified biochar is less porous than raw Egeria najas biochar, but loaded with γ-Fe 2 O 3 and Fe 3 O 4 crystals. In addition, the results of FTIR, XRD and XPS also confirmed that Fe was successfully loaded on the Egeria najas biochar. Cr(VI) was efficiently removed by FeCl 3 @EN-BC within the pH range from 2.5–8.5. The thermodynamics parameters suggested that the adsorption processes of Cr(VI) were all spontaneous and endothermic. The overall removal mechanism was regarded as adsorption, surface complex formation, reduction and ion exchange reaction. Therefore, this modified biochar derived from Egeria najas has a potential of practical application in the removal of Cr(VI) from wastewater. [Display omitted] • Novel Fe(III) modified Egeria najas driven-biochar was prepared. • A series of nano-sized γ-Fe 2 O 3 , Fe 3 O 4 were successfully introduced into biochar. • γ-Fe 2 O 3 enhance electrostatic interaction between Cr-containing anions and biochar. • Fe(III) oxide colloid has high chromium removal efficiency at a wide pH range. • Reaction mechanisms include adsorption, complexation, reduction and ion exchange. [ABSTRACT FROM AUTHOR]

The β‐hydrogen‐free imidazole monomer, 2‐methyl‐N‐methyl‐4(5)‐vinylimidazole (2M4VIm), is synthesized to prepare anion exchange membranes (AEMs). The radiation‐induced graft polymerization of 2M4VIm and styrene is performed in poly(ethylene‐co‐tetrafluoroethylene), followed by N‐alkylation and ion exchange reactions to prepare 4‐vinylimidazolium‐containing AEM (2M4VIm/St‐AEM). AEMs that have a 6/4 2M4VIm/St molar ratio and 1.7 mmol g−1 ion exchange capacity (IEC) result in 75 mS cm−1 conductivity and 60% water uptake at room temperature in water, demonstrating enhanced values compared to previously reported 2‐methyl‐N‐vinylimidazolium‐containing AEMs (2MNVIm/St‐AEM) that have a similar comonomer ratio and IEC. The small‐angle neutron scattering measurements of dry and swollen 2M4VIm/St‐AEM reveal hydrophilic/hydrophobic two‐phase separation, as observed for 2MNVIm/St‐AEM with a similar Im/St composition. 2M4VIm/St‐AEMs exhibit higher alkaline stability in 1 m KOH at 80 °C at an early stage owing to the suppression of imidazolium β‐elimination but lower long‐term stability than that of 2MNVIm/St‐AEM due to the ring‐opening reaction of the imidazolium group due to its outward orientation from the graft main chain. [ABSTRACT FROM AUTHOR]

Some basaltic eucrites and basaltic lithologies in howardites derived from the asteroid 4 Vesta exhibit unusual secondary veinlet textures consisting mostly of fayalitic olivine and Fe‐enrichments within pyroxenes. Recent studies discussed the formation of these Fe‐rich phases either by interaction with a vapor and/or liquid phase (metasomatism), or by a high‐temperature melting process. We therefore performed a series of heating and hydrothermal experiments with liquids of different compositions on natural pyroxene crystals (augite and orthopyroxene) to evaluate these contrasting hypotheses. The results of the heating experiments show that incongruent melting of pyroxenes at about 1070 °C causes textures that are very similar to those observed in the meteorites. We conclude that a part of the natural secondary veins might be explained by heating processes at similar temperatures. The hydrothermal experiments with aqueous liquids of different Fe‐enriched compositions clearly indicate ion exchange reactions resulting in partial Fe‐enrichments of the pyroxene. Interestingly, these Fe‐enrichments occurred independent of the Fe content of the liquid, which can be explained by an internal origin of Fe from the pyroxenes. In one hydrothermal experiment of augite with Fe‐oxalate solution, deposition of fayalitic olivine was observed. From our experimental observations, we conclude that aqueous liquids are plausible candidates for explaining the deposition of Fe‐enrichments and fayalitic olivine inside the fractures of pyroxene. However, we cannot rule out a high‐temperature melting process slightly above the peritectic point of pyroxene to explain a fraction of observed secondary Fe‐enrichments. [ABSTRACT FROM AUTHOR]

The sorption interaction of chromium(VI) ions with carbon adsorbents was studied by the physicochemical methods of energy dispersive X-ray spectroscopy, IR spectroscopy, and modeling using the Firefly801 program. A probable sorption mechanism is proposed, which can be considered as the sum of processes determined by external and internal diffusion of ions, electrostatic interaction, and ion exchange reactions. [ABSTRACT FROM AUTHOR]

• Bi 2 S 3 -BiOBr nanosheets were synthesized on TiO 2 NTA/Ti mesh. • The Bi 2 S 3 -BiOBr/TiO 2 NTAs showed the attractive hydrogen generation activity. • The active species and photocatalytic mechanism were studied. Novel energy material is the investigation focus to overcome the environment pollution and resource shortage crisis. TiO 2 nanotube arrays (TiO 2 NTA) could be used for pollutant decomposition, photoelectric conversion and H 2 , CH 4 generation. BiOBr nanosheets were fabricated on TiO 2 NTA by a solvothermal deposition method, and then transformed into Bi 2 S 3 nanosheets after the ion exchange reaction. The results revealed that the ion concentration significantly influenced the morphology, microstructure, optical harvesting and photoelectrochemical capacity of Bi 2 S 3 -BiOBr/TiO 2 NTA. The samples also exhibited high photocatalytic activity for the removal of dyes and Cr(VI), and the excellent photocurrent and photovoltage were obtained under visible light irradiation. The photocatalytic water splitting for hydrogen generation was carried out, and the photocatalytic hydrogen production rate achieved 17.26 μmol·cm−2·h−1. The photocatalyst showed the remarkable stability, and the photocatalytic ability still maintained high level after several repeated photocatalytic cycles. The photocatalytic data indicated that the Bi 2 S 3 -BiOBr/TiO 2 NTA photocatalyst provided a perfect strategy for the sensitizer deposition on TiO 2 NTA and novel approach for the photocatalytic performance improvement. [ABSTRACT FROM AUTHOR]

In recent years, more and more interest has been focused on the on-site sample preparation. Dispersive liquid–liquid microextractions without centrifugation or toxic organic solvent were developed and proved suitable for on-site extraction. In this study, a flexible dispersive liquid–liquid microextraction was developed for on-site water sample pre-concentration. A device containing a phase separation filter was prepared. By means of the phase separation filter packed with hydrophobic nonwoven polypropylene fibre, extraction phase and aqueous phase of the emulsified system were separated by manual filtration, which avoided the electric devices usually required in dispersive liquid–liquid microextractions. Combining the device with ionic liquid-based in situ dispersive liquid–liquid microextraction, a totally electricity-free procedure was developed. During the procedure, the extraction phase 1-hexyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide was formed through an ion exchange reaction, and then separated with water by filtration. After filtration, the extraction phase was eluted and submitted to high-performance liquid chromatography-variable wavelength detector for analysis. Parameters affecting the extraction performance were investigated and optimised. The optimised procedure achieved extraction recoveries of 75–89%. The intra-device, inter-device, intra-day and inter-day relative standard deviations were less than 4.6%. Good linearity (r2 > 0.9992) was obtained over the calibration range from 2 to 1000 µg L−1. The limits of detection of the method were in the range of 0.41–0.65 µg L−1. Because electric devices and organic dispersants are not required, the present approach is proved green, fast, and extremely flexible for on-site preparation of water sample. The proposed device is also expected to make other dispersive liquid–liquid microextractions transform into the on-site procedure. [ABSTRACT FROM AUTHOR]

In this paper, it was found that with the addition of sodium dodecyl sulfate (SDS, a hydrophilic surfactant) and oleic acid (OA, a lipophilic surfactant) in a solvent with a proper composition ratio, a stable gel could be obtained via a simple ultrasonic treatment. The synergistic gelation of OA–SDS was verified in a series of solvents with different polarities, such as white oil (WO), LB-2000, n-hexane, polyalphaolefin (PAO10), and deionized water. The Fourier transform infrared (FTIR) analysis confirms that the gelation of OA–SDS is highly related to the ion exchange reaction between them. However, the xerogel of OA–SDS gelator in deionized water and WO (OSW) exhibited remarkably different morphologies, indicating that the gelation is based on different molecular assembly processes, which is governed by the orientation of the two surfactant molecules in liquid media. Further characterizations of OSW gel presented that the synergistic effect between OA and SDS not only existed in gelation, but also in enhancing the mechanical and thermal stability of WO, and endowing the OSW gel with reliable friction reduction and antiwear performances under variable working conditions. Subsequently, the lubrication mechanism was proposed based on rheological analysis and the morphological and compositional analysis of wear surfaces. This study provides a novel idea for the molecular design of lubricating gelators with wide adaptability to solvent polarity and working conditions. [Display omitted] • The synergistic effect of OA and SDS on gelation and lubrication was presented. • The OA–SDS exhibits excellent gelling capacity in solvents of different polarities. • OA–SDS gelator in water and white oil have different gelling mechanisms. • OA–SDS gelator greatly improved the tribological properties of white oil. [ABSTRACT FROM AUTHOR]