Ion Exchange Process Research Articles

Hydrophobicity of montmorillonite synergistically controlled by silanization and aliphatic amine modification

The hydrophobic modification of montmorillonite significantly extends its potential applications across various industrial sectors. In this study, montmorillonite with controlled hydrophobicity was prepared based on Cu2+-exchanged montmorillonite by synergistic modification with perfluorodecyltrimethoxysilane and aliphatic amines. Our findings indicate that copper ion-exchange process not only increases the interlayer spacing of montmorillonite but also promotes the formation of antlerite crystals on its surface. The presence of interlayer water impedes the silanization process with perfluorodecyltrimethoxysilane, confining the grafting to the external surface of the clay. Consequently, this method can only increase the water contact angle (WCA) from 0° to 54.4°. Conversely, treatment with aliphatic amines removes interlayer water and establishes a hydrophobic structure on the internal surface, raising the WCA to 47.0°. Remarkably, the synergistic modification of perfluorodecyltrimethoxysilane and aliphatic amine resulted in a WCA of 157.3°. Further investigations demonstrated that adjusting the type and concentration of the aliphatic amines allows for precise control of WCA, enabling adjustments within the range of 54.4° to 157.3°. This study offers a viable approach for the controllable hydrophobic modification of montmorillonite.

Understanding adsorption mechanisms and metal ion selectivity of superparamagnetic beads with mesoporous CMK-3 carbon and commercial activated carbon

This study investigates, the adsorption capacities of synthesized magnetic hybrid beads containing ordered mesoporous carbon (CMK-3) and commercial activated carbon (commercial AC) for Cd (II), Ni (II), and Hg (II) ions adsorption in single and ternary systems. The order of maximum adsorption capacity was Cd (II) > Ni (II) > Hg (II) in both beads and systems. L13 beads containing CMK-3 exhibit superior adsorption efficiency compared to L3 beads with commercial AC, attributed to the large surface area, enhanced accessibility to adsorption sites, and the presence of O=C bonds, as well as other elements such as F−. Adsorption of all metal ions was described by Freundlich isotherm in L3 beads in both systems, meanwhile in L13 beads, Langmuir and Freundlich models described adsorption differently in both systems and among metal ions, indicating a more complex process. According to the reported maximum adsorption capacity values, L3 beads exhibit a greater affinity for Hg (II) ions, while L13 beads show a higher affinity for Cd (II) and Ni (II) ions. Adsorption in both beads occurred through several mechanisms involving surface complexation, ion-exchange, precipitation, physical and chemical processes. These findings highlight the importance of material design in optimizing adsorption performance for environmental applications, with potential for further enhancement of adsorption capacities and selectivities through future research.

Influence of clay minerals on pH and major cation concentrations in acid-leached sands: Column experiments and reactive-transport modeling

A series of laboratory experiments are conducted to simulate the acidification and subsequent recovery of a sand aquifer exploited by in situ recovery (ISR) mining. A sulfuric acid solution (pH 2) is first injected into a column packed with sand from the Zoovch Ovoo uranium roll front deposit (Mongolia). Solutions representative of local groundwater or enriched in cations (Na+, Mg2+) are then circulated through the column to simulate the inflow of aquifer water. pH and major ion concentrations (Na+, Cl−, SO42−, Ca2+, Mg2+, K+) measured at the column outlet reproduce the overall evolution of porewater chemistry observed in the field. The presence of minor quantities of swelling clay minerals (≈6 wt% smectite) is shown to exert an important influence on the behavior of inorganic cations, particularly H+, via ion-exchange reactions. Numerical models that consider ion-exchange on smectite as the sole solid-solution interaction are able to reproduce variations in pH and cation concentrations in the column experiments. This highlights the importance of clay minerals in controlling H+ mobility and demonstrates that sand from the studied aquifer can be described to a first order as an ion-exchanger. The present study confirms the key role of clay minerals in controlling water chemistry in acidic environments through ion-exchange processes. In a context of managing the long-term environmental footprint of industrial and mining activities (ISR, acid mine drainage…), this work will bring insights for modeling choices and identification of key parameters to help operators to define their production and/or remediation strategies.

Morphology modification of LiNi0.5Co0.2Mn0.3O2 by incorporating cotton textiles in lithium-ion capacitors

To address the alerting issue of energy demand, lithium-ion capacitors (LICs) have been widely studied as promising electrochemical energy storage devices, which can deliver higher energy density than supercapacitors (SCs), and have higher power density with longer cycling life than lithium-ion batteries (LIBs). In this work, the active material lithium nickel cobalt manganese oxide LiNi0.5Co0.2Mn0.3O2 (NCM523) is grown on a cotton textile template and building a 3-dimensional (3D) integrity to improve capacitance and energy density of LICs by enhancing the interfacial ion-exchange process. With the 3D structure, the specific discharge capacitance is increased to 718.67 F g−1 at 0.1 A g−1 from that of non-textile NCM523 (265.97 F g−1), and remains a high capacitance of 254.48 Fg−1 at 10 A g−1 in the half-cell capacitors. In addition, the energy density can achieve up to 36.17 Wh kg−1 at the power density of 1,200 W kg−1 in the full-cell capacitor. The textile NCM can maintain an energy density of 28.26 Wh kg−1 at the current density of 10 A g−1 and power density of 6,000 W kg−1. Our results present promising applications of electrodes with the 3D porous structure for high energy density LICs.

Eco-friendly closed-loop recycling of nickel, cobalt, manganese, and lithium from spent ternary lithium-ion battery cathodes

Recycling technology is essential for managing waste and addressing environmental issues related to scrapping power lithium batteries. A closed-loop recycling technique was proposed in this work for maximizing usage of lithium (Li), manganese (Mn), cobalt (Co), and nickel (Ni) resources in spent ternary lithium battery (SNCMB) cathodes. A green and sustainable leaching process utilizes citric acid (CA) and hydrogen peroxide (HP) to efficiently extract Ni, Co, Mn, and Li from SNCMB cathodes. Maximizing leaching rates for Ni (96.69 %), Co (95.38 %), Mn (97.64 %), and Li (98.72 %) under optimal conditions (80 ℃, 4 mol/L CA, 20 g/L solid to liquid (S/L) ratio, 2 vol% HP, 70 min). The Avrami equation models leaching kinetics, requiring a temperature of 80 ℃ to accelerate the process. Hydrogen-type strong acidic cation exchange resin (HR) effectively adsorbs Ni, Co, Mn, and Li ions from leachates through ion exchange under optimal conditions, reducing costs and eliminating the need for separating metals with similar chemical properties. This multi-stage adsorption recycling process renders leachates both economical and eco-friendly. The metal-enriched HR composite (HRC) from the ion-exchange process prepares ternary lithium battery (NCMB) cathodes to maximize metal usage. Microwave heating achieves excellent structure and electrochemical performance of regenerated ternary lithium battery (RNCM) cathodes, with 153.81 mAh/g discharge capacity at 0.1C rate and 90.92 % capacity retention after 50 cycles at 900 ℃ for 4 h. This innovative, efficient, and eco-friendly technique allows for closed-loop recycling of Ni, Co, Mn, and Li from SCNMB cathodes, providing new avenues for lithium battery recycling.

Steric, Synergetic, Energetic Studies on the Impact of the Type of the Hybridized Polymers (Chitosan and β-Cyclodextrin) on the Adsorption Properties of Zeolite-A for Congo Red Dye.

Zeolite-A was synthesized successfully from kaolinite and hybridized with two species of biopolymers (chitosan (CH/Z) and β-cyclodextrin (CD/Z)). The obtained hybridized forms were assessed as potential adsorbents of Congo red synthetic dye (CR) with enhanced affinities and elimination capacities. The synthesized CD/Z and CH/Z hybrids demonstrated uptake capacities of 223.6 and 208.7 mg/g, which are significantly higher than single-phase zeolite-A (140.3 mg/g). The integrated polymers change the surface area, surface reactivity, and number of free active receptors that are already present. The classic isotherm investigations validate Langmuir equilibrium behavior for ZA and Freundlich properties for CD/Z and CH/Z. The steric parameters validate a strong increase in the existing active receptors after the incorporation of CD (CD/Z) to be 98.1 mg/g as compared to 83 mg/g for CH/Z and 60.6 mg/g for ZA, which illustrate the detected uptake behaviors. Moreover, the CR dye was adsorbed as several molecules per single site, reflecting the vertical uptake of these molecules by multimolecular mechanisms. The energetic assessment, considering both Gaussian energies and adsorption energies (<40 kJ/mol), validates the dominant impact of the physical mechanism during the sequestration of CR (dipole binding interactions (2-29 kJ/mol) and hydrogen bonds (<30 kJ/mol)), in addition to the considerable effect of ion exchange processes. Based on the thermodynamic parameters, the CR molecules were adsorbed by exothermic and spontaneous reactions.

Mechanisms and physiological relevance of acid-base exchange in functional units of the kidney.

This review discusses the importance of homeostasis with a particular emphasis on the acid-base (AB) balance, a crucial aspect of pH regulation in living systems. Two primary organ systems correct deviations from the standard pH balance: the respiratory system via gas exchange and the kidneys via proton/bicarbonate secretion and reabsorption. Focusing on kidney functions, we describe the complexity of renal architecture and its challenges for experimental research. We address specific roles of different nephron segments (the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule) in pH homeostasis, while explaining the physiological significance of ion exchange processes maintained by the kidneys, particularly the role of bicarbonate ions (HCO3-) as an essential buffer system of the body. The review will be of interest to researchers in the fields of physiology, biochemistry and molecular biology, which builds a strong foundation and critically evaluates existing studies. Our review helps identify the gaps of knowledge by thoroughly understanding the existing literature related to kidney acid-base homeostasis.

Analysis of the adsorption and fixation process of ammonium nitrogen in arable soil by biochar based on molecular dynamics simulation

The ammonia nitrogen in arable land soil is susceptible to environmental and anthropogenic influences, leading to nutrient loss. This study utilized indoor soil column leaching experiments, combined with adsorption mathematical models, traditional characterization methods, and molecular dynamics simulation methods, to analyze the effects of biochar on changes in ammonium ions in different soil layers and leachate of arable land soil. The study found that applying biochar at a ratio of 10 % to arable land soil could effectively increase the ammonium ion content in the 0–10 cm soil layer by 1.57–2.36 times and reduce loss by 44.83–72.27 %. The adsorption and fixation process of biochar is controlled by electrostatic attraction and ion exchange processes. Interactions between molecules, electrostatic forces, and system internal energy also have certain effects on the process. Near the structure of C6H12O6, there are low-energy adsorption sites for ammonium ions, which can provide the energy required for electrostatic attraction. Structures such as C5H10O5, C-S-H, C-SO3, and C4H7NO4 respectively play roles in physical adsorption or chemical adsorption through displacement reactions, electron exchange, and other forms. The adsorption free energy is −394,590.84 kcal/mol, indicating stable adsorption and a process that tends to interact with the biochar surface. This study addresses issues such as the easy loss of ammonia nitrogen in arable land soil and the unclear adsorption mechanism of biochar on ammonium ions, providing a theoretical basis for the field of environmental science.

MAGNETIC MODIFICATION OF ION EXCHANGE PROCESSES

The method of ion exchange is widely used in modern water supply systems. Ion exchange units are used to correct the mineral composition of water to the required standards; wastewater treatment; desalination and softening of natural waters. Today, there are technical solutions to improve the process of water purification, softening and demineralization. They include: improvement of physical and chemical conditions; intensification of the ion exchange process; use of new ion exchange materials; modification of ion exchange resins; combination with other water treatment methods; modernization of equipment and designs of ion exchange devices. The paper investigates the effect of magnetic modification on the intensification of ion exchange processes during the adjustment of the mineral composition of natural waters. The obtained results demonstrate the influence of the magnetic field on the ion exchange process.

Removal of ciprofloxacin and heavy metals from water by bentonite/activated carbon composite: Kinetic, isotherm, thermodynamic and breakthrough curve modeling studies

This study explores the potential of a new, cost-effective adsorbent for removing ciprofloxacin (CIP) and heavy metals (HMs) from wastewater. This adsorbent is a mesoporous activated carbon (AC) crafted from sugarcane bagasse modified with bentonite (SCBB). The prepared composite was characterized using FTIR, XRD, SEM, and BET techniques. Optimal adsorption conditions were determined, with initial concentrations set at 15 and 300 mg/L, adsorbent doses at 100 and 50 mg, temperatures at 25 and 45 °C, and pH levels at 6 for CIP and HMs, respectively, in batch experiments. Kinetics data confirmed that adsorption follows pseudo-first-order model, with intraparticle diffusion identified as the rate-determining step. Three-parameter models were superior in describing experimental data compared to two-parameter models, with the Sips isotherm model indicating multilayer adsorption beyond monolayer saturation. Hydrophobicity likely plays a key role in CIP adsorption, potentially complemented by hydrogen bonding, while HMs are adsorbed through ion exchange, complexation, and pore diffusion processes. Furthermore, SCBB exhibited excellent adsorption performance (≥90 %) even after ten regeneration cycles. The impact of various operating parameters, including bed depth, feed concentration, and flow rate, were optimized in fixed bed column. Breakthrough data fitting the Dose Response, Thomas, and Yoon-Nelson models yielded high coefficients of determination (R2 ≥ 0.98). The techno-economic analysis identified SCBB preparation ($0.31/kg) as the main cost factor, but still predicts profitability with a payback period of 0.88 years and a break-even point of 58.6 %. Overall, the developed SCBB composite demonstrates significant potential as an efficient, cost-effective, and sustainable adsorbent, with applicability for the treatment of industrial wastewater contaminated with CIP and HMs.

DEVELOPMENT OF CRITERIA FOR EVALUATING STEEL REFINING PROCESSES USING INTERATOMIC INTERACTION PARAMETERS IN MELTS

To evaluate the efficiency of steel refining processes, the results of the physicochemical interaction of elements in the metal-slag system of ten steel grades smelted in modern conditions in Ukraine were analysed. As a result of the analysis of the patterns of changes in the distribution coefficients of sulphur and phosphorus depending on the chemical composition of steel and slag, physicochemical criteria for assessing the degree of completeness of ion exchange processes during steel dephosphorisation and desulphurisation have been developed using integral parameters of interatomic interaction in melts. Along with the use of integral physicochemical parameters of the chemical and charge state of the system ZY, e and Ze, the key role of the influence of the "recharge" parameter of the element ∆Ze on the process of sulfur and phosphorus distribution between metal and slag is shown and its use as a criterion for assessing the degree of deviation of the system from equilibrium is substantiated.

Interactions of proteins with heparan sulfate.

Heparan sulfate (HS) is a glycosaminoglycan, polysaccharides that are considered to have arisen in the last common unicellular ancestor of multicellular animals. In this light, the large interactome of HS and its myriad functions in relation to the regulation of cell communication are not surprising. The binding of proteins to HS determines their localisation and diffusion, essential for embryonic development and homeostasis. Following the biosynthesis of the initial heparosan polymer, the subsequent modifications comprise an established canonical pathway and a minor pathway. The more frequent former starts with N-deacetylation and N-sulfation of GlcNAc residues, the latter with C-5 epimerisation of a GlcA residue adjacent to a GlcNAc. The binding of proteins to HS is driven by ionic interactions. The multivalent effect arising from the many individual ionic bonds between a single protein and a polysaccharide chain results in a far stronger interaction than would be expected from an ion-exchange process. In many instances, upon binding, both parties undergo substantial conformational change, the resulting hydrogen and van der Waal bonds contributing significant free energy to the binding reaction. Nevertheless, ionic bonds dominate the protein-polysaccharide interaction kinetically. Together with the multivalent effect, this provides an explanation for the observed trapping of HS-binding proteins in extracellular matrix. Importantly, individual ionic bonds have been observed to be dynamic; breaking and reforming, while the protein remains bound to the polysaccharide. These considerations lead to a model for 1D diffusion of proteins in extracellular matrix on HS, involving mechanisms such as sliding, chain switching and rolling.

Understanding Na functions on distribution of Cu species within Cu-SSZ-13 for the selective reduction of NOx with NH3

Cu-SSZ-13 catalysts have been extensively investigated for NH3-SCR over numerous years. However, whether sodium (Na) promoted or inhibited the NH3-SCR performance of Cu-SSZ-13 catalysts was still controversial and needed to be further elucidated. In this work, two Cu-SSZ-13 catalysts, one containing Na and the other without Na, were prepared through a stepwise ion-exchange technique. The objective was to explore the promoting influence of Na on both catalytic activity and hydrothermal stability of Cu-SSZ-13. Analysis via H2-TPR and NH3-DRIFTS revealed a notable increase in the formation of [Cu(OH)]+-Z species due to the presence of Na. DFT calculations stimulated the ion-exchange process, and confirmed the migration of Cu species from 6MR to 8MR sites in the presence of Na. This study provides direct experimental evidence regarding the influence of Na on Cu distribution, thereby deepening the understanding of the interaction between Cu sites and co-cations.

Proposal and application of a novel isothermal model for the thermodynamic study of ion exchange reactions

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-, WO42-, MoO42-, PO43-, AsO43-, MoS2O22-, MoS42-) 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.

Comprehensive insight into the transformation mechanism of Cd fractionation in the components of paddy soils under cysteine leaching

Cadmium (Cd) contamination in paddy soils poses a serious threat to agricultural production and human health. In this study, cysteine was selected as the leaching agent for remediating Cd-contaminated paddy soils because of its effective, low cost and ecofriendly characteristics. Microcosmic simulation experiment was using to investigate the fate of Cd and elucidate the transformation mechanism of Cd in the key components of paddy soil under cysteine leaching. Results showed that the total Cd removal rate of paddy soils reached 46.8–87.4% under the optimal conditions. This was mainly attributed to the decrease of exchangeable fraction (F1), carbonate bound fraction (F2), iron/manganese-bound fraction (F3) and organic matter bound fraction (F4) of Cd. After cysteine leaching, soil fertility was promoted due to the increase in nitrate nitrogen (NN), ammonia nitrogen (AN), available phosphorus (AP) and organic matter (OM). pH, CaCO3, available potassium (AK), NN, AP, amorphous iron oxides (Feo) were the main contributors to Cd fractionation transformation. The desorption of Cd from ferrihydrite (Fh) and goethite (Gt) surfaces is hypothesized to stem from dual mechanisms: the dissolution due to the low solution pH and the reducibility of cysteine, which facilitated the conversion of Fh and Gt to hematite (Hm). And the -SH complexation also ascribed to the activation of Cd bound by Fe-OH in Fh and Gt and oxygen-containing functional groups in humic acid (Ha). For chlorite (Ch), the primary driver for Cd desorption was identified as an ion-exchange process, whereby electrostatically adsorbed Cd2+ were replaced by H+ produced by cysteine protonation.

DETERMINATION OF PHYSICAL AND CHEMICAL PARAMETERS OF WATER BEFORE AND AFTER ION EXCHANGE TREATMENT

In accordance with consumer requirements, the water must be adequately purified, and the corresponding parameters within the defined values. Various methods are used for this purpose, of which the ion exchange method can be highlighted as the simplest, most efficient and economically profitable. Ion exchange is a reversible process of ion exchange between a solid phase and an electrolyte solution. The ion exchanger is a macromolecular insoluble material that has chemically bound electrified groups and mobile, oppositely charged ions that compensate for this electrification. Ion exchangers are usually used in the form of compact or granular beds that fill the column through which the solution with the ions to be exchanged flows.They usually contain phenolic, carboxylic, sulfonic amino and other groups, which is why the treatment also results in decarbonization, softening, demineralization and denitrification of water. As the assessment of water quality is based on the most significant physico-chemical parameters, the aim of the work is the analysis of drinking water before and after treatment with an ion exchanger.For this purpose, organoleptic parameters such as smell, taste and color were first analyzed. After that, physico-chemical parameters were analyzed: pH values, electrical conductivity, m-alkalinity, p-alkalinity, water hardness, organic matter content, chloride content, iron and manganese content. An ion exchanger based on resin was used, which after use was regenerated by washing with NaClsolution.The analysis of the water sample, before and after the ion exchange treatment, showed that the treatment process was effective and that the decarbonization and softening of the water was carried out, whereby the water was categorized as soft water (water &lt;9⁰dH).The analyzed water is tasteless, odorless and colorless before and after treatment. The results of the analysis showed that all the values of the analyzedphysico-chemical parametersare in accordance with the Rulebook on the Healthiness of Drinking Water(Official Gazetteof Federation of Bosnia and Herzegovina No.40/10) arebelow the maximum allowed values. KEYWORDS:water, ion exchange, physical-chemical parameters; water treatment

Understanding Sorption of Aqueous Electrolytes in Porous Carbon by NMR Spectroscopy.

Ion adsorption at solid-water interfaces is crucial for many electrochemical processes involving aqueous electrolytes including energy storage, electrochemical separations, and electrocatalysis. However, the impact of the hydronium (H3O+) and hydroxide (OH-) ions on the ion adsorption and surface charge distributions remains poorly understood. Many fundamental studies of supercapacitors focus on non-aqueous electrolytes to avoid addressing the role of functional groups and electrolyte pH in altering ion uptake. Achieving microscopic level characterization of interfacial mixed ion adsorption is particularly challenging due to the complex ion dynamics, disordered structures, and hierarchical porosity of the carbon electrodes. This work addresses these challenges starting with pH measurements to quantify the adsorbed H3O+ concentrations, which reveal the basic nature of the activated carbon YP-50F commonly used in supercapacitors. Solid-state NMR spectroscopy is used to study the uptake of lithium bis(trifluoromethanesulfonyl)-imide (LiTFSI) aqueous electrolyte in the YP-50F carbon across the full pH range. The NMR data analysis highlights the importance of including the fast ion-exchange processes for accurate quantification of the adsorbed ions. Under acidic conditions, more TFSI- ions are adsorbed in the carbon pores than Li+ ions, with charge compensation also occurring via H3O+ adsorption. Under neutral and basic conditions, when the carbon's surface charge is close to zero, the Li+ and TFSI- ions exhibit similar but lower affinities toward the carbon pores. Our experimental approach and evidence of H3O+ uptake in pores provide a methodology to relate the local structure to the function and performance in a wide range of materials for energy applications and beyond.

Іntensification of ion exchange processes in water supply systems

In today's environment, special attention is paid to various methods of intensifying natural and wastewater treatment processes, improving existing treatment technologies, and introducing new methods and techniques to improve the quality of wastewater treatment and reduce the anthropogenic impact on the ecosystem. It is important to take into account not only the effectiveness of cleaning, but also its environmental friendliness and compliance with modern standards and requirements for environmental protection. This approach helps to ensure the sustainability of ecosystems and preservation of water resources for future generations. The article highlights the issues related to the use of physical methods of water treatment in water supply systems. To intensify the processes of ion exchange in water supply systems, a method of adjusting the mineral composition of natural and waste water using modified ion exchangers is proposed, which involves the simultaneous action of a magnetic field on the ion exchanger and the water to be treated. The use of magnetic modification of ion exchangers allows to increase the productivity of water treatment facilities by an average of 25-30%, with the receipt of filtrate of the required quality, to increase the duration of the filter cycle, to reduce the consumption of regenerative solutions, which indicates an increase in the efficiency of water treatment as a result of the use of magnetic modification. An increase in the dynamic volume capacity of ion exchangers by 15-20% was found, which indicates an improvement in ion exchange capacity due to the intensification of ion exchange processes in water supply systems. The intensification of ion exchange processes during the adjustment of the mineral composition of natural and wastewater using a magnetic field is determined by the following main factors: the effect of the magnetic field on the structure and properties of water filtered through the ionite and the effect of the magnet field on the activity and mobility of the exchanged ions, their diffusion and hydration, ion-exchange equilibrium, and other factors.

Hybrid exchange methods regulate Cu+ location on Cu-Y zeolites and improve CO adsorption capacity and selectivity

This work systematically examines the influence of preparation methods on the active Cu+ anchoring sites over FAU zeolites and their CO storage capacity and selectivity. The involved preparation methods here include individual liquid ion exchange method with CuCl2 solution, individual solid ion exchange method with CuCl powder and the hybrid exchange method. For the obtained Cu-Y samples, XRD, Ar adsorption/desorption at 87 K, TEM and NMR were used to characterize their skeleton structure, meanwhile, XPS and H2-TPR were utilized to identify the Cu+, Cu2+ and CuCl distribution. The CO storage capacity was implemented through CO adsorption–desorption isotherms. The correlation between various Cu species and CO storage capacity was analyzed and DFT calculation was employed to further elucidate the optimal Cu+ location induced by preparation methods. Finally, it is found that the isolated Cu+ is the dominating CO adsorption sites and Cu+ on site III present higher bonding energy with CO molecules. The hybrid preparation method seems the optimal choice for Cu-Y synthesis since the initial liquid ion exchange operation could prevent the framework corrosion from the subsequent solid ion exchange process, which benefits the optimal CO storage capacity and CO/N2 selectivity.

Coupling Reliable Interfacial Carrier Migration Channels with Visible-Light Response Antennas in ZnO-Based Heterostructure for Ameliorated Photocatalytic Hydrogen Generation.

Engineering targeted and reliable charge transfer pathways in multiphase photocatalysts remains a challenge. Herein, we conceptualize the Cd@CdS-ZnO/reduced graphene oxide (rGO)/ZnS heterostructures coupled with reliable carrier migration channels and visible-light response antennas by building rGO-integrated electrochemical nanoreactors and an ion-exchange process. In this ternary catalyst, the Cd clusters and rGO perform as charge relays to boost carrier transport via the Z-scheme route and accelerate photogenerated carriers to react with surface-adsorbed substances. Meanwhile, thanks to CdS, the heterostructures have photocatalytic properties under visible light illumination and can also inhibit self-corrosion by shielding Cd clusters to avoid disrupting charge transfer channels. Therefore, the special heterostructure demonstrates fascinating photocatalytic hydrogen production activity without the intervention of cocatalysts. This work provides a feasible protocol for improving the interfaces between metals and semiconductors to achieve efficient photocatalytic hydrogen generation.