Electrodialysis with anion-exchange membranes (AEMs) is effective for reclaiming alkaline substances from industrial effluents, but conventional AEMs suffer from active group degradation under harsh alkaline conditions. To address this limitation, we designed novel polyarylpiperidine-based AEMs using 1,6-dibromohexane as the cross-linker and incorporating varied side-chain groups. The optimized PBP-co-COOH AEM exhibited exceptional alkali stability: nuclear magnetic resonance confirmed polymeric backbone stability after 1200 ​h of exposure to 2.0 ​M NaOH at 80 ​°C, and thermogravimetric analysis showed minimal mass loss (<8.7 ​%). In practical electrodialysis (feed concentration: 0.40 ​M–0.11 ​M), this membrane achieved a high current efficiency of 90.21 ​% and low energy consumption of 2.22 ​kW ​h ​kg−1, outperforming the commercial Neosepta AHA membrane (80.31 ​% current efficiency, 2.75 ​kW ​h ​kg−1 energy consumption) in both metrics. These results demonstrate that modulating ionic moieties in membrane side chains significantly enhances electrodialysis performance. This membrane design provides a promising strategy for developing alkali-resistant AEMs, with valuable implications for optimizing alkaline reclamation processes and advancing industrial-scale applications.

Conventional solvent-resistant ion exchange membranes are predominantly fabricated via chemical crosslinking methods, which often involve complex processes, prolonged duration, and elevated costs. This study introduces metal coordination as an alternative approach. Through an immersion technique, Fe3+ ions are incorporated into sulfonated poly(arylene ether sulfone) (SPAES) membranes, where they coordinate with-NH groups to form a stable network structure. This strategy simultaneously enhances both the solvent resistance and desalination performance of the membranes. Research demonstrates that the SPAES-0.6Fe3+ membrane exhibits a surface resistance of 3.15 Omega cm2, a swelling rate of 6.30%, a desalination rate of 92.24%, and an energy consumption of 3.47 kWh/kg in a 50% DMSO system, surpassing the commercial ASTOM CMX membrane (desalination rate: 89.61%; energy consumption: 3.80 kWh/kg). In a 20% DMSO system, it maintains a high electrodialysis desalination efficiency of 92.30% after 1610 min, demonstrating exceptional desalination performance and significant energy-saving potential. In summary, the metal-coordination fabrication strategy proposed in this study demonstrates feasibility and high efficiency, successfully producing solvent-resistant cation exchange membranes (CEMs) with superior desalination performance and reduced energy consumption, thereby offering a novel direction for the development of advanced separation materials.

High-performance monovalent-selective anion exchange membranes (AEMs) are crucial for sustainable industrial wastewater treatment. This study addresses current AEM limitations by using brominated poly(phenylene oxide) (BPPO) as a base membrane and crosslinking it with polyethyleneimine (PEI) of varying molecular weights. The effects of membrane thickness and thermal treatment duration on membrane performance were also investigated to further optimize the properties. These parameters critically influence membrane microstructure (pore size, free volume, and charge density). This study optimized the membrane thickness, thermal treatment, and PEI molecular weight. High-molecular-weight PEI (25 k) was employed to construct high-density positively charged regions, enhancing SO42− rejection through synergistic Donnan exclusion. Stepwise thermal treatment promoted membrane densification and crosslinking, reducing free volume and micro-defects, thereby achieving a balance between low resistance and high selectivity. Compared to commercial membranes, the prepared membranes exhibit superior suitability for strong acidic environments. The resulting Cl−/SO42− perm-selectivity reached as high as 61.26 (in 0.05 mol/L Cl−/SO42− solution at 2.5 mA·cm−2), along with significantly enhanced acid stability and chemical durability. This work demonstrates that coordinated control of processing parameters and PEI molecular weight effectively optimizes ion transport channels, providing a strategic framework for designing high-performance, chemically durable ion-selective AEMs.

The ionic conductivity of polymers exerts a profound influence on the operational efficiency of energy conversion devices. Elevated conductivity efficiently mitigates ohmic resistance, thus optimizing the overall functionality of these systems. Previous research has demonstrated that incorporating naphthalene rings into polybenzimidazole (PBI) molecular structures confers exceptional oxidative stability to the material. In this work, low-content large 3D structures and highly rigid adamantane structures are introduced as branching points into the naphthalene-containing PBI, enabling it to absorb more electrolytes while improving dimensional stability. Specifically, upon phosphoric acid (PA) absorption, the branched 1.0Ad-NPBI membrane exhibited a proton conductivity of up to 155.8 mS cm-1. In an H2-O2 fuel cell (0.6 mg cm-2 Pt), it achieved a peak power density of 1022.4 mW cm-2 at 180 degrees C. After absorbing KOH solution, its hydroxide ion conductivity reached 176.7 mS cm-1, and it delivered a current density of 5.4 A cm-2 at 2.0 V in alkaline electrolytic water (AWE) cells (in 6 M KOH, at 80 degrees C). It confirms that branching is a very suitable strategy for improving the performance of PBI.

Zirconia-based membranes typically face a trade-off between ionic transport and gas barrier performance, limiting their effectiveness in alkaline water electrolysis, where low area resistance, high bubble-point pressure, and long-term stability are essential. Here we show a method for fabricating a nanoporous composite membrane. Yttria-stabilized zirconia nanoparticles are uniformly dispersed into a sol-state polybenzimidazole matrix via a one-pot sol-gel process. The resulting membrane exhibits a sponge-like, uniform nanoporous morphology with a high porosity of ~85%. Yet, it maintains a higher bubble-point pressure (>25 bar). Strong interfacial interactions exist between yttria-stabilized zirconia nanoparticles, phosphoric acid, and polybenzimidazole molecular chains. The synergistic multi-pathway structure facilitates continuous hydroxide ion migration. In alkaline water electrolysis, the membrane delivers a high current density of 13.1 A cm-2 at 2.0 V, and operates effectively over a wide range of alkaline electrolyte concentrations. Reinforcement with a polyphenylene sulfide mesh enables stable operation for 7000 h, and the membrane performs reliably in a large-area single-cell stack. This work introduces a scalable route to gel-state ceramic-polymer membranes for high-efficiency hydrogen production.

Saline wastewater poses not only an industrial environmental problem but also a global challenge for sustainable water management. This study addresses the issues of achieving zero liquid discharge and resource utilization of saline wastewater in the chemical industry by proposing an integrated membrane process based on bipolar membrane electrodialysis-electrodialysis (BMED-ED). A systematic investigation was conducted on the effects of key parameters, such as feed volume ratio and operating voltage, on the process performance, including energy consumption, current efficiency, flux, and purity. The process feasibility was further validated using different combinations of ion-exchange membranes. Under the optimized conditions of an initial BMED volume ratio of 2:1:1 at 20 V and an initial ED volume ratio of 4:1 at 5 V, the process efficiently converted a 1 mol center dot L-1 NaCl solution into 2 mol center dot L-1 HCl, with a specific energy consumption of 3.23 kWh center dot kg-1 HCl. The entire process requires no addition of other chemicals, is environmentally friendly, and demonstrates good technical feasibility and application potential, showing promise as a green route for wastewater zero liquid discharge.

The rapidly increasing demand for lithium resources has driven significant advances in membrane-based separation technologies for extracting lithium from salt lake brines. However, conventional polymer membranes often suffer from key challenges of permeability and perm-selectivity. Herein, we have constructed a functional sieving layer for monovalent-ion-selective membranes through interfacial polymerization by incorporating UiO-66-NH2 with poly(diallyldimethylammonium chloride) (PDADMAc) polyelectrolyte, which has been successfully applied in electrodialysis processes for efficient Li+/Mg2+ separation. The fabricated membranes have facilitated Li+ transport while blocking Mg2+ effectively, owing to the synergistic effect between stable electrostatic repulsion and sufficient functional transport channels. Experimental results have shown that the membranes have exhibited extremely high permeation fluxes of monovalent ions (Li+/Na+): the permeation flux of Li+ reaches 1.59 & times; 10-8 mol cm-2 s-1, the permeation flux of Na+ reaches 1.48 & times; 10-8 mol cm-2 s-1, whereas the corresponding Mg2+ flux is only 0.40 & times; 10-8 mol cm-2 s-1. These results correspond to high separation selectivities of PNa+/Mg2+ = 26.2 and PLi+/Mg2+ = 32.2, which markedly outperform commercial membranes and those reported in published studies. It also provides a novel electrodialysis strategy for Li+/Mg2+ separation by leveraging MOF-based membranes, offering valuable insights for the efficient recovery of monovalent ion resources.Keywords: Electrodialysis-based monovalent/multivalent ion sieving; Metal-organic framework; Interfacial polymerization; High Li+ permeation flux; High perm-selectivity.

Anion exchange membrane water electrolysis (AEMWE) has great potential for hydrogen production from electrolytic water. However, the low chemical stability and ionic conductivity of the membrane limit its development. In this study, a series of crosslinked AEMs CMPS-DO-x were prepared using a simple preparation: quaternization and crosslinking during the membrane formation process. The crosslinked membranes exhibited superior stability and ionic conductivity due to the crosslinked structure restricting the SR as well as the special conformation of quaternization reagent with cage-like structures, compared with the uncrosslinked membrane quaternized by trimethylamine. All crosslinked membranes showed superior performance, especially CMPS-DO-40 showed the optimal comprehensive properties: at 80°C, it had low swelling ratio of 19.4%, moderate water uptake of 61.6%, and high ionic conductivity of 137.6 mS cm- 1. In addition, it also exhibited strong alkaline stability with a conductivity retention rate of 87.7% after 1128 h in 1 M KOH at 60°C. The AEMWE assembled with this membrane exhibits excellent performance of 2V@5.46 A cm- 2 at 80°C. In addition, the membrane CMPS-DO-40 was subjected to AEMWE durability tests at 0.5 A cm-2 for 180 h, showing considerable durability and verifying its potential for AEMWE application.

For the purpose of large-scale and long-duration energy storage, vanadium redox flow batteries (VRFBs) have emerged as a highly promising electrochemical solution. These systems require membranes exhibiting high stability and selectivity. Conventional microphase-separated membranes, however, often face a trade-off between achieving high ionic conductivity and minimizing active species crossover, compounded by long-term chemical stability challenges. To address this, we designed a supramolecular interaction-mediated strategy for the in situ synthesis of covalent organic frameworks (COFs) within ion transport channels. Highly sulfonated polymer chains provide SO3H groups that serve as supramolecular interaction sites for COF precursors, offering ordered templates for crystallization. The resulting optimized membrane exhibits a molecular sieving effect within its ion channels, demonstrating superior ion selectivity (VO2+ permeability, P: 3.24 x 10(-8) cm(2) s(-1); selectivity, S: 5.70 x 10(5)) and stable flow battery performance (coulombic efficiency, CE > 99.6 %; energy efficiency, EE > 78.89 % over 500 cycles). The performance surpasses that of Nafion 212 and several previously reported membranes. This work presents a simple method for modifying ion transport channels-leveraging supramolecular interactions without damaging the polymer backbone-and offers new perspectives on applying COFs in ion exchange membranes (IEMs).

High-performance monovalent-selective anion exchange membranes (AEMs) are crucial for sustainable industrial wastewater treatment. This study addresses current AEM limitations by using brominated poly(phenylene oxide) (BPPO) as a base membrane and crosslinking it with polyethyleneimine (PEI) of varying molecular weights. The effects of membrane thickness and thermal treatment duration on membrane performance were also investigated to further optimize the properties. These parameters critically influence membrane microstructure (pore size, free volume, and charge density). This study optimized the membrane thickness, thermal treatment, and PEI molecular weight. High-molecular-weight PEI (25 k) was employed to construct high-density positively charged regions, enhancing SO42- rejection through synergistic Donnan exclusion. Stepwise thermal treatment promoted membrane densification and crosslinking, reducing free volume and micro-defects, thereby achieving a balance between low resistance and high selectivity. Compared to commercial membranes, the prepared membranes exhibit superior suitability for strong acidic environments. The resulting Cl-/SO42- perm-selectivity reached as high as 61.26 (in 0.05 mol/L Cl-/SO42- solution at 2.5 mA·cm-2), along with significantly enhanced acid stability and chemical durability. This work demonstrates that coordinated control of processing parameters and PEI molecular weight effectively optimizes ion transport channels, providing a strategic framework for designing high-performance, chemically durable ion-selective AEMs.

The instability of ion exchange membranes (IEMs) in organic solvents severely limits their application in electrodialysis (ED) for treating organic wastewater. Herein, we report a series of polybenzimidazole (PBI)-based anion exchange membranes (AEMs) cross-linked with gamma-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), in which the silane network serves a dual-function as both a rigidifying scaffold and an auxiliary ion-conducting phase, a concept we term the "triple-phase architecture". Unlike conventional crosslinking that merely stabilizes the matrix, the KH560 network exploits the intrinsic reactivity of PBI's imidazole N sites to form covalent Si-O-Si linkages that irreversibly lock the polymer chains against solvent swelling, while simultaneously creating hydrophilic, positively-chargeable pathways that facilitate selective Cl-transport. This synergistic design yields membranes exhibiting Cl-/SO(4)(2- )perm-selectivity (276.15) among the highest values reported and exceptional stability in harsh organic solvents (80 degrees C DMSO, <5% mass loss over one week), significantly advancing beyond our previous work that relied solely on side-chain microphase separation or inert crosslinking.

The industrial application of modified ion-exchange membranes is limited by complex, discontinuous ex-situ processes. This study introduces an in-situ electro-assembly strategy that enables the direct fabrication of a selective layer within an electrodialysis stack without disassembly. By utilizing a programmed current reversal to orchestrate the sequential deposition of polyethyleneimine (PEI), glutaraldehyde cross-linking, and polystyrene sulfonate (PSS) adsorption, we achieve meticulous interfacial engineering on a commercial cation exchange membrane. Comprehensive characterization confirms the successful construction of a hydrophilic, charge-tuned multilayer, which enhances ion transport kinetics and raises the limiting current density. This method culminates in a membrane with an exceptional Li+/Mg2+ selectivity of 107.9 and robust stability, retaining a significant selectivity of 47 over 10 cycles in real salt lake brine. This synergistic integration of operational simplicity, interfacial precision, and superior performance establishes a transformative and scalable platform for manufacturing high-performance membranes for selective ion separation from complex brine sources.

Kevlar aramid nanofiber (KANF) membranes face a critical permeability-selectivity trade-off. Conventional structural modulation strategies-such as nanomaterials blending or interfacial polymerization aim to enhance permeance while preserving their exceptional separation selectivity. However, these approaches often yield heterogeneous membrane architectures with severe stability issues. Inspired by the advanced structure of thin-film composite (TFC) membranes, we developed a bilayer KANF composite membrane via the “solution-on-solution” fabrication method. The structural superiority manifests in homogeneous aramid nanofibers at the interlayer interface, which form a dense hydrogen-bonded network that enhances interlayer connectivity and bolsters the mechanical integrity of the entire architecture. Remarkably, the composite membrane achieves a 12-fold enhancement in solvent permeability compared to the pristine membrane, while maintaining outstanding rejection for small molecules. This work provides a paradigm-shifting strategy for designing high-performance nanofiltration membranes through interfacial synergy and structural gradation.

The efficient utilization of salt lake resources depends critically on the precise separation of distinct cations from brine. Conventional monovalent-selective cation exchange membranes (MSCEMs) are often constrained by a trade-off between permeability and selectivity. To address this, we developed a high-performance membrane by grafting a positively charged covalent organic framework (COF) onto a commercial cation exchange membrane via a swelling-embedding method. This approach creates a nanoscale modification layer that enhances both ion flux and perm-selectivity. Investigation into the interfacial properties revealed that the two-dimensional crystalline COFs regulate the arrangement of positively charged groups, thereby strengthening the electrostatic repulsion against multivalent cations and facilitating the rapid transport of monovalent ions. The resulting membrane achieved exceptionally high perm-selectivity PNa+Mg2+= 34.3, PLi+Mg2+ = 25.2) while maintaining high ion flux (JNa + = 1.94 & times; 10-8 mol & sdot;cm-2 & sdot;s-1, JLi += 1.25 & times; 10-8 mol & sdot;cm-2 & sdot;s-1), significantly outperforming commercial benchmarks. In this work, the influence of monomer concentration on membrane performance was systematically investigated. This study not only presents a novel strategy for fabricating highly selective CEMs but also elucidates the underlying separation mechanism, providing valuable insights for the recovery of monovalent cations.

Organic electrochemical transistors (OECTs) are attractive for wearable bioelectronics and smart textiles owing to their mixed ionic-electronic conduction and biocompatibility. The function of these transistors relies on a channel made of a 1D conducting polymer, which is essential for converting ionic signals into amplified electronic outputs. However, classical 1D polymer channels such as PEDOT:PSS suffer from severe swelling and instability in aqueous environments, limiting device reliability. Here, we introduce a framework-confinement strategy that inserts PEDOT:PSS into the nanopores of β-ketoenamine covalent organic frameworks (COFs) functionalized with carboxyl or sulfonic groups. Strong hydrogen-bonding interactions effectively suppress polymer swelling, thereby enhancing long-term operational stability. The composite COF/PEDOT:PSS fibers, produced via scalable wet-spinning, exhibit remarkable mechanical robustness with a tensile strength of 464.7 MPa. As OECT channel materials, the fibers retain over 90% of their initial performance after 1000 s of cycling, demonstrating exceptional durability. This work offers a promising route to overcome the problem of structural failure of 1D conductive polymers in aqueous media, paving the way for high-performance and durable bioelectronic textiles.

Achieving an optimal balance between phosphoric acid (PA) uptake and membrane dimensional stability remains a critical challenge for the electrochemical performance and long-term durability of PA-doped membranes in high-temperature proton exchange membrane fuel cells (HT-PEMFCs). Herein, dual proton conductor HT-PEMs were prepared by PA immersion of diethylenetriamine penta-(methylene phosphonic acid) (DETPMP) doped branched poly(triphenyl trifluoroacetophenone piperidone) composite membranes. The unique benzimidazole-functionalized side-chains, combined with the branched rigid twisted polymer backbone, create a robust hydrogen bonding network that facilitates efficient proton transport. By tailoring the polymer structure, the optimized dual-proton conductor membrane, b-PTTP-BIm-DP20, achieves a lower PA uptake (<130 %), while exhibiting outstanding proton conductivity (168.5 mS cm(-1)), excellent dimensional stability, and sufficient PA retention. The PA-doped b-PTTP-BIm-DP20 based HT-PEMFCs delivers a remarkable peak power density of 835.1 mW cm(-2) (200 degrees C) under backpressure-free and non-humidified. Additionally, the PA-doped b-PTTP-BIm-DP20 membrane demonstrates exceptional durability, with a voltage decay rate of only 0.556 mV h(-1) at 160 degrees C over 100 h of continuous operation. This work highlights the potential of branched polymer designs incorporating dual-proton conductors to achieve a synergistic balance between membrane dimensional stability and electrochemical performance, offering valuable insights for the development of advanced HT-PEMFC membranes.

The key challenge in creating HT-PEMs lies in attaining an optimal balance between the capacity to adsorb phosphoric acid (PA) and preserving structural integrity. The effective method to solve this problem is to obtain composite membranes by adding organic proton conductors during the membrane preparation process of ether-free branched structure polymers, and then soaking PA to form the double proton conductor HT-PEMs. However, different branched structures often bring different structures and properties to the prepared diproton conductor HT-PEMs. In this study, three types of ether-free aromatic piperidine pyridine polymers with different branched structures were successfully prepared through superacid-catalyzed polymerization. Compared with linear polymers, especially the b-PTAZ-DP composite membrane containing the N-rich triazine ring branched structure has the best microphase separation morphology and shows excellent comprehensive performance. The PA-doped double proton conductor b-PTAZ-DP has sufficient H+ conductivity (154 mS cm(-1)) under the condition of low PA uptake (184 %), and the maximum output power of single-cell reaches 970.9 mW cm(-2) at 200 degrees C without humidification and backpressure, showing excellent cell performance. This research presents innovative and significant perspectives on the molecular structure design and synthetic preparation of HT-PEMs with highperformance ether-bond-free branched structures that achieve good balance between PA uptake and dimensional stability.

In response to the impending freshwater crisis, this study aims to enhance the efficiency of electrodialysis (ED) desalination membranes and address critical challenges in practical applications of ion exchange membranes, such as insufficient stability and environmental sensitivity. Specifically, we focused on mitigating structural degradation and performance deterioration in anion exchange membranes (AEMs) caused by alkaline conditions during ED. A series of AEMs with tunable grafting ratios of fluorinated side chains were synthesized using poly (aryl piperidine) (PBP) as the polymer backbone and ionic liquid QF as the quaternary ammonium-functionalized fluorinated side chain. The effects of side-chain grafting ratios on ED performance were systematically investigated, complemented by long-term stability tests under alkaline conditions. Results demonstrate that the QPBP-20 %QF-C membrane exhibits optimal water uptake, dimensional stability, low electrical resistance, and superior electrochemical properties. In ED desalination, this membrane achieved a salt removal rate of 90.9 %, current efficiency of 86.4 %, and energy consumption of 3.53 kW & sdot;h & sdot;kg-1, outperforming conventional commercial AEMs. Critically, it retained stability throughout a 720-h alkaline endurance test. Specifically, the IEC retention ratio of QPBP-30QF-C after alkali exposure is 80.5, and the membrane with the best desalination performance still maintains a desalination efficiency of 88.65 %. This work provides a viable strategy for fabricating alkali-resistant AEMs and advances the application of ether-free polymers in sustainable desalination technologies.

In electrodialysis technology applications, anion-exchange membranes (AEMs) have great potential in recovering alkali from industrial wastes and are expected to recover alkali from industrial wastes. In this study, a series of AEMs based on polyarylpiperidines crosslinked with varying ratios of siloxanes were synthesized. Compared to the uncrosslinked PBP AEM and commercial Neosepta AHA, biphenylpiperidine-based AEMs (PBP-CPMTS40 and PBP-CPMTS60) demonstrated superior ion flux, alkali separation performance, and economic efficiency due to their optimized water uptake (WU) and ion exchange capacity (IEC). Notably, PBP-CPMTS60 AEM exhibited optimal water swelling, low membrane resistance (1.98 Omega & sdot;cm2), and the highest OH-conductivity (14.1 mS & sdot;cm-1) at room temperature. It also demonstrated excellent alkali stability, retaining 89.71 % of its IEC and 85.07 % of its OH-conductivity after 1200 h of exposure to 2 M NaOH at 80 degrees C. During Cl-and OH-ion separation via electrodialysis, the dilution compartment concentration decreased from 0.40 M to 0.12 M within 180 min, achieving a high current efficiency of 87.21 % and an energy consumption of 2.32 kW & sdot;h & sdot;kg-1. This study presents a rational siloxane crosslinking strategy to mitigate AEM degradation in alkaline environments, offering significant potential for electrodialysis-based alkali concentration application.