Monovalent Cations Research Articles

Mammalian PIEZO channels rectify anionic currents.

Under physiological conditions, mammalian PIEZO channels (PIEZO1 and PIEZO2) elicit transient currents mostly carried by monovalent and divalent cations. PIEZO1 is also known to permeate chloride ions, with a Cl- / Na+ permeability ratio of about 0.2. Yet, little is known about how anions permeate PIEZO channels. Here, by separately measuring sodium and chloride currents using non-permanent counter-ions, we show that both PIEZO1 and PIEZO2 rectify chloride currents outwardly, favoring entry of chloride ions at voltages above their reversal potential, whereas little to no rectification was observed for sodium currents. Interestingly, chloride currents elicited by 9K, an anion-selective PIEZO1 mutant harboring multiple positive residues along intracellular pore fenestrations, also rectify but in the inward direction. Molecular dynamics simulations reveal that the inward rectification of chloride currents in 9K correlates with the presence of a large positive electrostatic potential at intracellular pore fenestrations, suggesting that rectification can be tuned by the electrostatic polarity of the pore. These results demonstrate that the pore of mammalian PIEZO channels inherently rectifies chloride currents.

Synergistic Regulation of DNA Morphology by Metal Cations and Low pH.

As a flexible biomolecule, the spatial structure of DNA is variable. The effects of concentration, metal cations, and low pH on DNA morphology were studied. For the high concentration of DNA, the cross-linked branch-like or network structures were formed. For the low concentration of DNA, isolated, random and freely loose linear DNA chains were presented. These phenomena were related to the intermolecular interactions. Branch-like DNA structures were reformed with the addition of metal cations to the low concentration of DNA at pH 7-4, suggesting the negative charges of DNA were neutralized, thus transforming the spatial structure of DNA into a low charge density morphology and presenting the hypochromic effect. Compared to the monovalent alkaline metal cations, more negative charges of DNA were screened by the alkaline-earth metal cations. Distinct DNA morphologies were observed for pH 3. The linear and condensed DNA structures were simultaneously observed, which was met regardless of the solution with or without the addition of metal cations. This was further confirmed by the absorbance of DNA. Compared to the pure DNA, bulky and aggregated DNA collapsed structures were formed when the sodium and magnesium cations were added to the reaction solution. In addition, it was verified that the condensed DNA structures failed to revert back to the chain structure by neutralizing acidic solutions with alkali, but the compacted DNA spheres became loose. The conductivities of various DNA morphologies were measured. They were morphology-dependent. This study provides guidance forthe behavior of DNA in the acidic solutions and further promotes the application of DNA in DNA-based nano-optoelectronic devices.

A DFT Study of Band-Gap Tuning in 2D Black Phosphorus via Li+, Na+, Mg2+, and Ca2+ Ions.

Black phosphorus (BP) and its two-dimensional derivative (2D-BP) have garnered significant attention as promising anode materials for electrochemical energy storage devices, including next-generation fast-charging batteries. However, the interactions between BP and light metal ions, as well as how these interactions influence BP's electronic properties, remain poorly understood. Here, we employed density functional theory (DFT) to investigate the effects of monovalent (Li+ and Na+) and divalent (Mg2+ and Ca2+) ions on the valence electronic structure of 2D-BP. Molecular orbital analysis revealed that the adsorption of divalent cations can significantly reduce the band gap, suggesting an enhancement in charge transfer rates. In contrast, the adsorption of monovalent cations had minimal impact on the band gap, suggesting the preservation of 2D-BP's intrinsic electrical properties. Energetic and charge analyses indicated that the extent of charge transfer primarily governs the ability of ions to modulate 2D-BP's electronic structure, especially under high-pressure conditions where ions are in close proximity to the 2D-BP surface. Moreover, charge polarization calculations revealed that, compared with monovalent cations, divalent cations induced greater polarization, disrupting the symmetry of the pristine 2D-BP and further influencing its electronic characteristics. These findings provide a molecular-level understanding of how ion interactions influence 2D-BP's electronic properties during ion-intercalation processes, where ions are in close proximity to the 2D-BP surface. Moreover, the calculated diffusion barrier results revealed the potential of 2D-BP as an effective anode material for lithium-ion, sodium-ion, and magnesium-ion batteries, though its performance may be limited for calcium-ion batteries. By extending our understanding of interactions between ions and 2D-BP, this work contributes to the design of efficient and reliable energy storage technologies, particularly for the next-generation fast-charging batteries.

Ultra-fast interlayer construction strategy for the preparation of NF membranes with high Li+/Mg2+ separation performance

Nanofiltration (NF) membranes have demonstrated significant potential in lithium extraction from salt-lake brines due to their superior selectivity in separating monovalent cations from divalent cations. In this paper, NF membranes with high permeate flux and high lithium-magnesium separation factor (SLi,Mg) were prepared by using a polyamide (PA) layer as the separation layer, RA-PEI as the interlayer, and a polysulfone (PSf) membrane as the substrate membrane. Notably, the RA-PEI co-deposition modification method is an ultra-fast substrate modification method, requiring only 1s for modifying PSf substrates. At the same time, RA-PEI firmly adheres to the surface of the PSf substrate by the synergistic effects of intermolecular hydrogen bonding interactions and π-π interactions. This was further verified by comparing the adsorption energies of different kinds of organic interlayers and PSf substrates obtained from molecular dynamics (MD) simulations. Correlation characterization showed that the RA-PEI interlayer endowed the NF membranes with reduced average pore size as well as attenuated electronegativity, thus realizing the efficient separation of Mg2+ and Li+. The performance assessment showed that the membrane containing RA-PEI interlayer exhibited excellent separation performance and permeate flux in simulated salt-lake brine (2000 ppm, WMg/Li = 20), where SLi,Mg (92.8) and permeate flux (16.7 L·m−2·h−1·bar−1) were improved by 7.8 and 2.2 times, respectively, in comparison to the pristine NF membrane. Therefore, this work provides a useful contribution to the practical use of NF membranes for lithium extraction from salt lakes.

Epitaxial Growth of Silver Clusters from Ag57 to Ag72 via Laminating Multiple Different Anion Templates

The established capability of anion templates in precisely manipulating the size, geometry, and function of metal clusters is well acknowledged. However, the development of a systematic methodology for orchestrating the assembly of silver clusters, particularly those encompassing multiple distinct types of anion templates, remains elusive due to the formidable synthetic challenge. In this work, we report two novel silver clusters, Ag57 and Ag72, using two and three different anion templates, respectively. Ag57 features a gyroscope‐like monovalent cation with an Ag3 triangle core sandwiched by one [SiW9O34]10− and a triad of Cl− anion templates. By intentionally introducing the third anion template, SO42−, the structure is expanded to the unprecedented Ag72 (with 15 silver atoms epitaxially grown on top of Ag57) resembling a tumbler, inside of which two Ag3 layers are laminated by one [SiW9O34]10−, seven Cl− and one SO42− anion templates in parallel with respect to longitudinal orientation. It is noteworthy that Ag72 exhibits remarkable structural complexity and represents a pioneering achievement as the first silver cluster incorporating three distinct types of anion templates. In addition, Ag72 demonstrates a significant advantage over Ag57, particular in terms of applications such as luminescent thermometers and remote laser ignition.

Epitaxial Growth of Silver Clusters from Ag57 to Ag72 via Laminating Multiple Different Anion Templates.

The established capability of anion templates in precisely manipulating the size, geometry, and function of metal clusters is well acknowledged. However, the development of a systematic methodology for orchestrating the assembly of silver clusters, particularly those encompassing multiple distinct types of anion templates, remains elusive due to the formidable synthetic challenge. In this work, we report two novel silver clusters, Ag57 and Ag72, using two and three different anion templates, respectively. Ag57 features a gyroscope-like monovalent cation with an Ag3 triangle core sandwiched by one [SiW9O34]10- and a triad of Cl- anion templates. By intentionally introducing the third anion template, SO42-, the structure is expanded to the unprecedented Ag72 (with 15 silver atoms epitaxially grown on top of Ag57) resembling a tumbler, inside of which two Ag3 layers are laminated by one [SiW9O34]10-, seven Cl- and one SO42- anion templates in parallel with respect to longitudinal orientation. It is noteworthy that Ag72 exhibits remarkable structural complexity and represents a pioneering achievement as the first silver cluster incorporating three distinct types of anion templates. In addition, Ag72 demonstrates a significant advantage over Ag57, particular in terms of applications such as luminescent thermometers and remote laser ignition.

Axial heterogeneity of superficial proximal tubule paracellular transport in mice.

A considerable amount of NaCl reabsorption in proximal tubules (PTs) occurs via the paracellular transport regulated by the tight junction proteins claudins (Cldns). However, the paracellular transport properties in mouse superficial PTs remain unclear. We characterized these properties in superficial PT S1-S3 segments from mice expressing [wild-type (WT, WTS1-WTS3)] or lacking claudin-2 [knockout (KO, KOS1-KOS3)]. We isolated and perfused segments with symmetrical solutions in the presence of bath ouabain and measured the diffusion potential upon changing the salt composition of the lumen or bath. Based on the diffusion potential corrected for the liquid junction potential (dVT), we calculated the paracellular Na+ over Cl- permeability (PNa/PCl) ratio. The PNa/PCl values upon reducing luminal NaCl averaged 1.27, 1.04, and 0.85 in WTS1, WTS2, and WTS3 and 0.34, 0.55, and 0.80 in KOS1, KOS2, and KOS3, respectively. The dVT values exhibited a symmetrical response to bidirectional NaCl concentration gradients in WTS1-WTS3 and KOS1-KOS3. WTS1 and WTS3 were monovalent cation-selective, with WTS1 demonstrating stronger cation selectivity. The order of permeabilities relative to Cl- was K+ > Rb+ > Na+ > Li+, whereas both KOS1 and KOS3 exhibited monovalent cation selectivity loss and consequently enhanced anion selectivity, especially in KOS1. Protamine addition to the lumen and bath similarly decreased PNa/PCl values upon reduced luminal NaCl in the order of WTS1 > WTS3 > KOS3 > KOS1. Therefore, this study presents evidence of axial heterogeneity in paracellular transport across superficial PTs in mice.

Cryo-EM structure of the heteromeric TRPC1/TRPC4 channel.

Transient receptor potential (TRP) ion channels have a crucial role as cellular sensors, mediating diverse physical and chemical stimuli. The formation of heteromeric structures expands the functionality of TRP channels; however, their molecular architecture remains largely unknown. Here we present the cryo-electron microscopy structures of the human TRPC1/TRPC4 heteromer in the apo and antagonist-bound states, both consisting of one TRPC1 subunit and three TRPC4 subunits. The heteromer structure reveals a distinct ion-conduction pathway, including an asymmetrically constricted selectivity filter and an asymmetric lower gate, primarily attributed to the incorporation of TRPC1. Through a structure-guided electrophysiological assay, we show that both the selectivity filter and the lower part of the S6 helix participate in deciding overall preference for permeating monovalent cations. Moreover, we reveal that the introduction of one lysine residue of TRPC1 into the tetrameric central cavity is enough to render one of the most important functional consequences of TRPC heteromerization: reduced calcium permeability. Our results establish a framework for addressing the structure-function relationship of the heteromeric TRP channels.

Insights into the wetting mechanisms in low-permeability sandstone reservoirs and its evolution processes: The shahejie formation in the Dongying Depression, Bohai Bay basin

During the accumulation and development processes of low-permeability oil, wettability plays a crucial role in the percolation capacity of fluids. In particular, the evolution of low-permeability sandstones involves complex changes in formation fluid properties and mineral types, leading to a deficient understanding of wetting mechanisms in low-permeability sandstones. This gap significantly impedes research on the accumulation mechanisms of low-permeability oil. Focusing on the low-permeability sandstones in Shahejie formation of Dongying Depression, Bohai Bay Basin, tests like Casting thin section, scanning electron microscope, contact angle measurement, molecular dynamics simulation and the Amott method based on nuclear magnetic resonance technology were performed to comprehensively investigate sandstone wettability and its evolutionary process. The results indicate that the adsorption capacity of hydroxyl groups or monovalent cations (K+and Na+) for water molecules causes residual intergranular pores, feldspar dissolution pores, quartz dissolution pores, clay mineral intercrystalline pores and micro-cracks to exhibit hydrophilicity; while the adsorption capacity of divalent cations (Ca2+and Mg2+) for oil molecules causes the surface of dissolution pores of carbonate minerals to exhibit neutrality or lipophilicity. Additionally, changes in formation conditions (temperature, pressure, ion types, and ion concentration) significantly control the wettability of pore surfaces, further determining the overall wettability of low-permeability sandstone reservoirs. Throughout the evolutionary process of low-permeability sandstones, the Amott-Harvey index of low permeability sandstone is greater than zero, and the wettability exhibited hydrophilic or neutral. From A-stage eodiagenesis to B-stage mesodiagenesis, the Amott-Harvey index is 0.82, 0.12, 0.37, 0.03, and 0.49, and the wettability of reservoirs transitions through phases of strong hydrophilicity, weak hydrophilicity, hydrophilicity, neutrality, and hydrophilicity, respectively. Finally, an evolutionary model of the wettability of low-permeability sandstone reservoirs was established, which is of great significance for predicting the quality of low-permeability sandstone reservoirs.

Dynamic Surface Interactions Enable the Self-Assembly of Perfect Supramolecular Crystals.

Supramolecular crystals arise from noncovalent interactions between macromonomers and allow for the engineering of dynamic functional materials. For two-dimensional (2D) crystals, the substrate surface can induce the formation of new polymorphs not available in solution, adding a layer of complexity to the supramolecular self-assembly process. Despite extensive studies on the 2D self-assembly of supramolecular crystals, unknowns remain regarding substrate-monomer interactions and the effects on network self-assembly and defect repair. Here, we used a DNA-mica model system to modulate and understand the impact of substrate-monomer interactions on the crystalline order. We controlled the surface interactions by tuning the Mg2+ concentration, varying the divalent cation type, and adjusting the relative concentration of divalent and monovalent cations. The competition between monovalent and divalent cations yielded nearly defect-free crystals with minimal polygon defects. These findings highlight the critical role of surface interactions in achieving high crystalline order, which is essential for optimizing the efficiency and performance of supramolecular functional nanomaterials.

Toward a Circular Lithium Economy with Electrodialysis: Upcycling Spent Battery Leachates with Selective and Bipolar Ion-Exchange Membranes.

Recycling spent lithium-ion batteries offers a sustainable solution to reduce ecological degradation from mining and mitigate raw material shortages and price volatility. This study investigates using electrodialysis with selective and bipolar ion-exchange membranes to establish a circular economy for lithium-ion batteries. An experimental data set of over 1700 ion concentration measurements across five current densities, two solution compositions, and three pH levels supports the techno-economic analysis. Selective electrodialysis (SED) isolates lithium ions from battery leachates, yielding a 99% Li-pure retentate with 68.8% lithium retention, achieving relative ionic fluxes up to 2.41 for Li+ over transition metal cations and a selectivity of 5.64 over monovalent cations. Bipolar membrane electrodialysis (BMED) converts LiCl into high-purity LiOH and HCl, essential for battery remanufacturing and reducing acid consumption via acid recycling. High current densities reduce ion leakage, achieving lithium leakage as low as 0.03%, though hydronium and hydroxide leakage in BMED remains high at 11-20%. Our analysis projects LiOH production costs between USD 1.1 and 3.6 per kilogram, significantly lower than current prices. Optimal SED and BMED conditions are identified, emphasizing the need to control proton transport in BMED and improve cobalt-lithium separation in SED to enhance cost efficiency.

Synthesis and Characterization of Low-Dimensional Quaternary Sulfides of Thallium, Tl2Cu2GeS4, Tl2Ag2GeS4, and Tl2Ag2SnS4.

Three new low-dimensional quaternary sulfides, namely, Tl2Cu2GeS4(1), Tl2Ag2GeS4(2), and Tl2Ag2SnS4(3) were synthesized by solid-state reactions and characterized by single-crystal X-ray diffraction, spectroscopic, thermal, and photocatalytic studies. The compounds 1, 2, and 3, respectively, have centrosymmetric layered, noncentrosymmetric layered, and noncentrosymmetric one-dimensional structures, in which Cu+, Ge4+, and Sn4+ ions have tetrahedral coordination and Ag+ ion has linear, trigonal planar and tetrahedral coordinations. The monovalent thallium cations have TlS8 dodecahedral coordination and TlS7 and TlS6 coordination polyhedra of irregular shape. The compounds 1, 2, and 3 are semiconductors with the respective energy band gap values of 1.68, 2.02, and 1.90 eV. Compared to compounds 1 and 2, compound 3 has a higher efficiency value of 22.9% for the photodegradation of aqueous solution of methylene blue. Band structures and projected density of states of all three compounds were computed using density functional theory, and these results are in good agreement with experiments.

Engineering of Covalent Organic Framework Nanosheet Membranes for Fast and Efficient Ion Sieving: Charge-Induced Cation Confined Transport.

Artificial membranes with ion-selective nanochannels for high-efficiency mono/divalent ion separation are of great significance in water desalination and lithium-ion extraction, but they remain a great challenge due to the slight physicochemical property differences of various ions. Here, the successful synthesis of two-dimensional TpEBr-based covalent organic framework (COF) nanosheets, and the stacking of them as consecutive membranes for efficient mono/divalent ion separation is reported. The obtained COF nanosheet membranes with intrinsic one-dimensional pores and abundant cationic sites display high permeation rates for monovalent cations (K+, Na+, Li+) of ≈0.1-0.3mol m-2 h-1, while the value of divalent cations (Ca2+, Mg2+) is two orders of magnitude lower, resulting in an ultrahigh mono/divalent cation separation selectivity up to 130.4, superior to the state-of-the-art ion sieving membranes. Molecular dynamics simulations further confirm that electrostatic interaction controls the confined transport of cations through the cationic COF nanopores, where multivalent cations face i) strong electrostatic repulsion and ii) steric transport hindrance since the large hydrated divalent cations are retarded due to a layer of strongly adsorbed chloride ions at the pore wall, while smaller monovalent cations can swiftly permeate through the nanopores.

Charge‐Sign‐Independent Separation of Mono‐ and Divalent Ions With Nanofiltration Membranes

AbstractAchieving precise selective separation of monovalent and divalent cations, as well as anions, is vital yet challenging in practical applications involving complex component treatments. Current membranes are typically effective for separating either cation pairs or anion pairs. To address this issue, a straightforward strategy for fabricating a nanofiltration (NF) membrane is developed that selectively permeates monovalent ions. This study focused on neutralizing the surface charge and tuning the pore size distribution of the polyamide membranes through a secondary interfacial polymerization using a zwitterionic copolymer consisting of 2‐methacryloyloxyethyl phosphorylcholine and 2‐aminoethyl methacrylate hydrochloride. The optimized NF membrane prepared in this study, with a near‐neutrally charged membrane surface and appropriate pore size distribution, demonstrates favorable performance in precisely separating monovalent and divalent ions, irrespective of the ion charge sign. The optimum NF membrane features high selectivity for both Cl−/SO42− (93) and Li+/Mg2+ (67) ion pairs, along with high water permeance of 8.5 L m−2 h−1 bar−1, making it competitive with many reported membranes. This study offers new insights into the ion‐selective mechanisms of polyamide membranes for monovalent/divalent ions and may guide the development of advanced membranes with single‐solute selectivity.

Triclinic polymorph of bis[2-methyl-3-(pyridin-2-yl)imidazo[1,5-a]pyridin-2-ium] tetrachloridocadmium(II)

The crystal structure of the title organic–inorganic hybrid salt, (C13H12N3)2[CdCl4], (I), has been reported with four molecules in the asymmetric unit in a monoclinic cell [Vassilyeva et al. (2021). RSC Advances, 11, 7713–7722]. While using two different aldehydes in the oxidative cyclization–condensation involving CH3NH2·HCl to prepare a new monovalent cation with the imidazo[1,5-a]pyridinium skeleton, a new polymorph was obtained for (I) in space group P 1 and a unit cell with approximately half the volume of the monoclinic form. The structural configurations of the two crystallographically non-equivalent organic cations as well as the geometry of the moderately distorted tetrahedral CdCl4 2– dianion show minor changes. In the crystal, identically stacked cations and tetrachlorocadmate anions form separate columns parallel to the a axis. The loose packing of the anions leads to a minimal separation of approximately 9.53 Å between the metal atoms in the triclinic form versus 7.51 Å in the monoclinic one, indicating that the latter is packed slightly more densely. The two forms also differ by aromatic stacking motifs. Similar to the monoclinic polymorph, the triclinic one excited at 364 nm shows an intense unsymmetrical photoluminescent band with maximum at 403 nm and a full width at half maximum of 51 nm in the solid state.

Insights into the Molecular Structure, Stability, and Biological Significance of Non-Canonical DNA Forms, with a Focus on G-Quadruplexes and i-Motifs

This article provides a comprehensive examination of non-canonical DNA structures, particularly focusing on G-quadruplexes (G4s) and i-motifs. G-quadruplexes, four-stranded structures formed by guanine-rich sequences, are stabilized by Hoogsteen hydrogen bonds and monovalent cations like potassium. These structures exhibit diverse topologies and are implicated in critical genomic regions such as telomeres and promoter regions of oncogenes, playing significant roles in gene expression regulation, genome stability, and cellular aging. I-motifs, formed by cytosine-rich sequences under acidic conditions and stabilized by hemiprotonated cytosine–cytosine (C:C+) base pairs, also contribute to gene regulation despite being less prevalent than G4s. This review highlights the factors influencing the stability and dynamics of these structures, including sequence composition, ionic conditions, and environmental pH. Molecular dynamics simulations and high-resolution structural techniques have been pivotal in advancing our understanding of their folding and unfolding mechanisms. Additionally, the article discusses the therapeutic potential of small molecules designed to selectively bind and stabilize G4s and i-motifs, with promising implications for cancer treatment. Furthermore, the structural properties of these DNA forms are explored for applications in nanotechnology and molecular devices. Despite significant progress, challenges remain in observing these structures in vivo and fully elucidating their biological functions. The review underscores the importance of continued research to uncover new insights into the genomic roles of G4s and i-motifs and their potential applications in medicine and technology. This ongoing research promises exciting developments in both basic science and applied fields, emphasizing the relevance and future prospects of these intriguing DNA structures.

Accumulation of Li+ Ions Triggers Changes in FOS, JUN, EGR1, and MYC Transcription in the LiCl-Treated Human Umbilical Vein Endothelial Cells (HUVEC).

Changes in intracellular concentrations of Na+ and K+ are shown to alter gene expression. Another monovalent cation, Li+, is well known as a medicine for treatment of psychiatric disorders, but mechanism of its action is obscure. Thus, it is important to evaluate the effect of Li+ on gene expression in endothelial cells. Here we studied influence of the increased intracellular Na+ or Li+ concentrations on transcription of Na+i/K+i-sensitive genes. Treatment of the human endothelial cells (HUVEC) with LiCl for 1.5h resulted in accumulation of Li+ in the cells. This was followed by increase in the FOS and EGR1 mRNAs levels and decrease in the JUN and MYC mRNA levels. Treatment of HUVEC with the Na+-ionophore monensin led to accumulation of Na+ and loss of K+ ions. However, monensin had no significant effect on gene expression. Incubation of HUVEC with elevated extracellular NaCl concentration increased intracellular K+ concentration and transcription of the ATF3 gene, while transcription of the JUN gene decreased. These results indicate that Na+ and Li+ ions have different effects on the gene expression profile in the cells that is likely associated with the fact that they affect differently the intracellular monovalent cations ratio.

Comparative study of silica-based porous materials in the purification of radioactive wastewater

A significant challenge in the treatment of low-level radioactive wastewater is the effective purification of low-concentration radionuclides. Silica-based adsorbents are advantageous for the deep-purification of low-concentration metal ions. This study investigates three primary types of silica-based adsorbents: functionalized mesoporous silica, various modified zeolites, and mesoporous calcium silicate hydrate (C-S-H). These adsorbents were synthesized and their deep-purification effects on heavy metals and radionuclides were compared. The results indicated that mesoporous silica showed relatively poor adsorption for most metal ions. Zeolites outperformed mesoporous silica, with Zn framework-modified zeolites showing enhanced adsorption for several metal ions. Notably, C-S-H displayed superior adsorption performance, achieving high adsorption capacities for various metal ions and radionuclides. Specifically, at a dose of 0.5 g/L, the adsorption efficiency of C-S-H for numerous radionuclides in nuclear power plant wastewater exceeded 92–99 %, highlighting its potential for practical applications. An in-depth analysis of the physical and chemical structure and the adsorption mechanisms of C-S-H revealed its large mesoporous structure and electrostatic attraction to cations across a wide pH range. Multivalent cations were removed through exchange with Ca2+ in C-S-H, whereas monovalent cations were removed through exchange with Na+ in C-S-H. The cyclic structure of silica-oxygen tetrahedra in C-S-H, which promotes large pore formation and provides abundant ion exchange sites, underpins its excellent adsorption properties. This study offers valuable insights for the selection and application of silica-based materials in radioactive wastewater treatment.

Having their cake and eat it too: Effects of different cations in reduced-salt myofibrillar protein microgel pickering emulsion under high-intensity ultrasound

Health concerns have increased the demand for low-salt emulsified meat products emulsions; however, salt-soluble myofibrillar proteins (MP) are less than optimal emulsifiers under low-salt conditions. In this study, four different cations (Na+, K+, Ca2+, and Mg2+) were added to a Pickering emulsion and high-intensity ultrasound (HIU, 20 kHz, 600 W) was used to determine the quality of the final emulsion. The divalent cation group was found to significantly (P < 0.05) improve the emulsification performance of the emulsion; in particular, the emulsion activity index and emulsion stability index of Mg2+-H group increased to 16.24 ± 1.22 m2/g and 89.66 ± 3.01%, respectively. Measurements of the particle size and zeta potential confirmed that the emulsion particle size of the Mg2+-H group decreased, and the electrostatic repulsion force increased. Based on the surface hydrophobicity and endogenous tryptophan spectra, the particle structure of the MP microgel was determined to be a more stable emulsifier. What's more, the divalent cations promoted the droplets to become evenly dispersed under high-intensity ultrasound. The micrograph confirmed this result: the divalent cation group emulsion was more uniform and stable than the monovalent cation group emulsion. Divalent cations are more suitable than monovalent cations for improving the quality of reduced-salt Pickering emulsions.

Boosting lithium/magnesium separation performance of selective electrodialysis membranes regulated by enamine reaction

Monovalent cation exchange membranes (MCEMs) have progressively played an important role in the field of ion separation. However, according to transition state theory (TST), synchronously tuning the enthalpy barrier (△H) and entropy barrier (△S) for cation transport to improve ion separation performance is challenging. Here, the enamine reaction between the -NH- and -CHO groups is applied to regulate the subsequent Schiff-base reaction between the -CHO and -NH2 groups, which reduces the positive charges of the selective layer but increases the steric hindrance. The increased -T△S (△S term) for cation transport plays an important role in improving Li+/Mg2+ separation performance. The optimal positively-charged glutaraldehyde@piperazine/polyethyleneimine assembled membrane (M-Glu@PIP/PEI) has a perm-selectivity (Li+/Mg2+) of 31.83 with a Li+ flux of 1.87 mol·m-2·h-1, surpassing the Li+/Mg2+ separation performance of state-of-the-art monovalent ion selective membranes (MISMs). Most importantly, the selective electrodialysis (S-ED) process with M-Glu@PIP/PEI can be directly applied to treat simulated salt-lake brines (SLBs), and its superior Li+/Mg2+ separation performance and operational stability enables 74.44% of the lithium resources with a Li+ purity of 34.02% to be recovered. This study presents new insights into the design of high-performance MCEMs for energy-efficient resource recovery.