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Constructing a functional layer on the surface of commercial membrane (as a substrate) to inhibit the formation of biofilms is an efficient strategy to prepare an antibacterial anion exchange membrane (AEM). Herein, a rechargeable multifunctional anti‐biological system is reported by utilizing the mussel‐inspired L‐dopa connection function on commercial AEMs. Cobalt nanoparticles (Co NPs) and N‐chloramine compounds are deposited on the AEM surface by a two‐step modification procedure. The anti‐biofouling abilities of the membranes are qualitatively and quantitatively analyzed by adopting common Gram‐negative (E. coli) and Gram‐positive (S. aureus & Bacillus) bacteria as model biofouling organisms. The optimized membrane exhibits a high stability concerning the NaCl solution separation performance within 240 min. Meantime, the mechanism of the anti‐adhesion is un‐veiled at an atomic level and molecular dynamics (MD) simulation are conducted to measure the interaction, adsorption energy and average loading by using lipopolysaccharide (LPS) of E. coli. In view of the superior performance of antibacterial surfaces, it is believed that this work could provide a valuable guideline for the design of membrane materials with resistance to biological contamination. [ABSTRACT FROM AUTHOR]

Mono-valent selective ion-exchange membrane, as the core component of selective electrodialysis (SED), has received extensive attention. In this work, we report a mono-valent selective anion-exchange membrane (AEM), which was fabricated with distorted poly(aryl ether sulfone) and decorated with bifunctional side-chains providing anion exchange groups and hydrophobic segments. By tuning the length of the hydrophobic side-chains, the nanophase separation within AEMs was finely tuned, evidenced by an ionic cluster size of about 0.47 nm from SAXS analysis. The optimized AEM (PAES-TA-7 AEM) shows a very low water swelling ratio of 6.4 %, signaling good dimensional stability. The perm-selectivity (P S O 4 2 – C l – ) of PAES-TA-7 AEM during ED reached 107 at 2.5 mA∙cm−2 (ion flux: 2.69 × 10−8 mol cm−2 s−1 at 90 min) significantly exceeding that of the commercial Neosepta ACS (11; 2.08 × 10−8 mol cm−2 s−1). It is inferred that the ion channels, resulting from nanophase separation between the side-chains and the backbone, as well as the free volume cavity created by the distorted backbone, significantly contribute to the smooth transport of the Cl− ions through the AEM with less resistance. As a result, it is believed that this work offers a useful strategy to advance the monovalent anion-selective membranes. [Display omitted] • A monovalent selective AEM based on distorted PAES decorated by bifunctional side-chains has been prepared. • The optimized AEM shows low water absorption and swelling ratio with the values of 12.4 % and 6.4 %, respectively. • The P S O 4 2 – C l – of the PAES-TA-7 AEM reaches 107 at mA∙cm−2, significantly exceeding that of Neosepta ACS (11). • The bifunctional side-chains and the distorted backbone significantly contribute to the transport of Cl− through the AEM matrix. [ABSTRACT FROM AUTHOR]

Abstract Fabricating stable mono-/multi-valent anion-selective membranes with high perm-selectivity for electrodialysis (ED) applications is critical but challengeable. In this work, we have fabricated a series of novel homogeneous monovalent anion-selective amphoteric ion-exchange membranes (AIEMs, PAES-im-Xc) based on a long-side-chain type imidazolium-functionalized poly(arylene ether sulfone) cross-linked with 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt (DAS) for ED. By tuning the mass percent of DAS added, low swelling ratio but appreciably high anion perm-selectivity (in Cl–/SO 4 2– system) of optimized AIEM are achieved to values of 8.0% and 47.12 at current density of 2.5 mA cm–2, respectively. In particular, at an enhanced current density of 5.0 mA cm–2, its perm-selectivity reaches 12.5, significantly outperforming commercial monovalent anion-selective Neosepta ACS (5.27). The appreciably high perm-selectivity possibly arises from pore-size sieving effect from dense matrix structure with cross-linkings and strong electrostatic repulsion between negative fixed –SO 3 – groups and negative divalent ions of SO 4 2– in feeding solution. The superior performances might be particularly interesting findings that can facilitate the development of advanced mono-/bi-valent anion-selective membranes in applications of sea water desalination, resource recovery and water treatment/pretreatment etc.. Graphic abstract fx1 Highlights • A series of novel homogeneous monovalent anion-selective AIEMs has been fabricated for ED. • By tuning the content of cross-linker, low swelling ratio but high perm-selectivity are achieved. • The optimized AIEM shows the perm-selectivity (P S O 4 2 − C l − ) of 12.5, outperforming Neosepta ACS (5.27). • Pore-size sieving effect and electrostatic repulsion contribute to high perm-selectivity a lot. [ABSTRACT FROM AUTHOR]

Abstract Developing highly ion conductive and desirable electrodialysis (ED) performance anion exchange membranes (AEMs) is of great significance. In this work, we report a strategy for fabricating novel AEMs based on a series of fluoro-methyl poly(arylene ether ketone)s having long-side-chain imidazolium groups for ED. Having hydrophilic conductive flexible side-chain imidazolium groups and rigid hydrophobic backbone within AEM matrix, the optimized AEM (PAEK-60-im) shows low water uptake of 24.9% at 80 °C and desirable ion conductivity of 22.01 mS cm–1 at 30 °C. In NaCl removal application of ED, PAEK-60-im shows the NaCl removal ratio of 69.66% within 120 min, outperforming commercial AEM-Type II (68.98%). Accordingly, it has a higher current efficiency of 83.7% but lower energy consumption of 5.9 kWh kg–1, compared with the commercial one (82.0%; 6.6 kWh kg–1). In particular, in selectrodialysis application, possibly owing to the synergistic effect of pore-size sieving effect resulting from macro-separation morphology and hydration energy difference of SO 4 2– ions (–1000 kJ mol–1) and Cl– ions (–317 kJ mol–1) in feeding solution, PAEK-60-im shows significantly superior monovalent anion perm-selectivity (Cl−/SO 4 2−) of 7.70 at 30 min, relative to commercial anion-selective Neosepta ACS (5.27) and many other reported mono-valent anion selective AEMs having elegant surface modified layers. The superior ED performance of the homogeneous PAEK-60-im is suggestive of its potential separation application. Highlights • Imidazolium-functionalized fluoro-methyl poly(arylene ether ketone) AEMs have been prepared. • The optimized AEM shows water uptake of 24.9% at 80 °C and ion conductivity of 22.01 mS cm–1 at 30 °C. • The NaCl removal ratio within 2 h of optimized AEM is 69.66%, outperforming that of AEM-Type II (68.98%). • The optimized AEM has a significantly high perm-selectivity (Cl-/SO 4 2-) of 7.70 at 30 min in selectrodialysis. [ABSTRACT FROM AUTHOR]

Surface modification is a critical method for fabricating novel anion exchange membranes (AEMs) with high monovalent anion selectivity and desired antifouling property. In this work, we have modified a commercial AEM with “sandwich”-like structure, composed of upper/bottom bilayers of polydopamine (PDA) and sandwich alternating bilayers of poly (sodium 4-styrene sulfonate) (PSS)/hydroxypropyltrimethyl ammonium chloride chitosan-nano silver particles (HACC-Ag Np), aiming to enhance the monovalent selectivity and fouling resistant for electrodialysis (ED) application. Our investigations suggest that the permselectivity ( P S O 4 2 − C l − ) of the modified AEM with 4.5 bilayers of PSS can reach 5.1, significantly outperforming that of commercial standard AEM (0.98). Due to the electrostatic repulsion resulted from the negatively charged top layer in sandwich structure and hydrophilia of PDA, the time elapsed until the occurrence of fouling (transition time) of the modified AEM (125 min) is much longer than that of the original one (60 min). In addition, anchored silver nanoparticles in sandwich alternating bilayers endow the modified AEMs with effective antibacterial activities of Escherichia coli. These results are indicative of the desired fouling resistant for ED process. The facile fabrication process and superior performances of modified AEM suggest that the as-prepared “sandwich”-like structure modified AEM is potentially applicable in ED for separation of monovalent and multivalent anions. [ABSTRACT FROM AUTHOR]

In this work, amphoteric ion-exchange membranes (AIEMs) prepared from fluoro-methyl sulfonated poly(arylene ether ketone- co -benzimidazole)s have been systematically evaluated for their potential usage in all vanadium redox battery (VRB). Our investigation has demonstrated that the compacted structure originated from the self-assembly ionic cross-linking and the positive charged benzimidazole moiety in AIEM matrix could synergistically reduce the vanadium species cross-contamination. The self-discharge time of a single cell assembled with AIEM of optimized chemical structure is over 3 times longer than that with Nafion117, and a desirable conductivity/permeability trade-off can be achieved by tuning the content of benzimidazole moiety. Single cell assembled with the optimized AIEM exhibit higher battery efficiencies and lower capacity loss than that with Nafion117 at current densities of 30, 50 or 70 mA cm −2 . Furthermore, the AIEMs are able to tolerate the strong oxidizing VO 2 + and remain intact for over 370 days, as revealed from ex -situ chemical stability tests. These findings strongly suggest that the as-prepared AIEM can be a good candidate for low-cost and high-performance separator in VRB application. [ABSTRACT FROM AUTHOR]

The development of stable ion exchange membranes applied in organic solution systems can expand the scope of practical applications. In this work, to explore the organic solvent anion exchange membranes (AEMs), a series of pyridine salt side-chains grafted poly(2,6-dimethyl-1,4-phenyl oxide)-based AEMs have been prepared for electrodialysis (ED). It is interestingly found that the as-prepared AEMs bear 3D network structure. Investigation demonstrates that the optimized AEM (BPPO-APy-6C) has an acceptable surface area resistance of 5.93 Ω·cm2 and the low swelling ratio of 2.5 % in DMSO. As for BPPO-APy-6C AEM exposed to a mixture solvent of 60 % DMSO +40 % water for 90 d, no visible appearance change is observable, indicating the improved organic solvent resistance. This has also been verified by the high desalination ratio (98.0 %) of ED with AEM after being exposed to 20 % DMSO (aq.) for 20 d. In addition, the DMSO-treated BPPO-APy-6C AEM-based ED filled with DMSO-containing 0.5 M NaCl solution shows the similar desalination ratio to that of ED with 0.5 M NaCl solution (aq.), suggesting its superior capacity of tolerating polar organic solvent. It is reasoned that the cross-linked structure and hydrophobicity of alkyl segments within AEM significantly contribute to the enhanced organic solvent resistance. [Display omitted] • A series of pyridine salt-side chains grafted PPO AEMs has been prepared. • The optimized AEM shows the low swelling ratio of 2.5 % in DMSO at room temperature. • The as-prepared AEM exposed to 60 % DMSO (aq.) for 90 d still remains integrity. • The DMSO-treated AEM shows desalination ratio of 98.0 % and organic solvent resistance. [ABSTRACT FROM AUTHOR]

The development of organic solvent resistant ion exchange membranes (IEMs) with high ion conductivity is of significance for broader electrodialysis (ED) applications. In this work, a series of organic solvent resistant cation exchange membranes (CEMs) has been fabricated by splitting Kevlar fabrics into small and short nanofibers, followed by modifying with 4-amino-benzenesulfonic acid monosodium salt (ABS) and poly(4-styrenesulfonic acid- co -maleic acid) sodium salt (PSSMA) eater via amide condensation. By tuning the content of ABS, the as-prepared poly- p -phenylene terephthalamide sulfonated polymer (PAP) CEMs (PAP-CEMs) show high ion exchange capacities (up to 2.23 mmol⋅g−1), good electrochemical performance and desired capacity of cation/anion separation in ED. To evaluate the organic solvent resistance of as-prepared CEMs, PAP-CEMs were immersed in ethanol and acetone aqueous solutions for 48 h at room temperature, respectively. The investigation demonstrates that ED with the treated CEM (the optimized PAP-0.50 CEM) still exhibits high desalination efficiencies (81.2%, in 60% (V ethanol /V water) ethanol solution; 82.3%, in 60% (V acetone /V water) acetone solution) and concentration efficiencies (57.4%, in 60% ethanol solution; 50.9%, in 60% acetone solution). As a result, it is believed that the study here highlights a design of simple route for the preparation of CEMs, which can be potentially applied in ED for organic solvent solution systems. [Display omitted] • A series of Kevlar nanofiber-based CEMs has been prepared for ED applications. • The as-prepared CEM shows a high ion exchange capacity up to 2.23 mmol g−1. • The optimized CEM exhibits high desalination efficiencies in 60% ethanol solution. • The work provides a method for the preparation of organic solvent resistant CEMs. [ABSTRACT FROM AUTHOR]

Developing monovalent cation permselective membranes (MCPMs) with high-efficient permselectivity is the core concern in specific industrial applications. In this work, we have fabricated a series of novel cation exchange membranes (CEMs) based on sulfonated polysulfone (SPSF) surface modification by polyethyleneimine (PEI) and 4′-aminobenzo-12-crown-4 (12C4) codeposited with dopamine (DA) successively, which was followed by the cross-linking of glutaraldehyde (GA). The as-prepared membranes before and after modification were systematically characterized with regard to their structures as well as their physicochemical and electrochemical properties. Particularly, the codeposition sequence of modified ingredients was investigated on galvanostatic permselectivity to cations. The modified membrane (M-12C4-0.50-PEI) exhibits significantly prominent selectivity to Li+ ions ( P Mg 2 + Li + = 5.23) and K+ ions ( P Mg 2 + K + = 13.56) in Li+/Mg2+ and K+/Mg2+ systems in electrodialysis (ED), which is far superior to the pristine membrane (M-0, P Mg 2 + Li + = 0.46, P Mg 2 + K + = 1.23) at a constant current density of 5.0 mA·cm−2. It possibly arises from the synergistic effects of electrostatic repulsion (positively charged PEI), pore-size sieving (distribution of modified ingredients), and specific interaction effect (12C4 ~Li+). This facile strategy may provide new insights into developing selective CEMs in the separation of specific cations by ED. [ABSTRACT FROM AUTHOR]

Ion selective separations play crucial roles in the fields of energy storage, pollution management, and industrial processes, etc. Ion exchange membranes (IEMs) offer promise for these separations but often lacking the required selectivity. In this work, we have developed a kind of IEM based on metal-organic frameworks (MOFs) to enhance membrane separation performance for electrodialysis (ED). Specifically, for poly(arylene ether sulfone)-based anion exchange membranes (AEMs), we introduced the modified MOFs through doping to create a transport pathway for target ions, leveraging their precise size-based separation effects. This approach significantly improves ion selectivity. Remarkably, at a current density of 2.5 mA·cm−2, the monovalent ion selectivity (Cl−/SO 4 2−) of PAES-UIO-66-Pyr could reach 54.26, while the monovalent ion selectivity (NO 3 −/SO 4 2−) could reach 55.90. These enhancements may stem from the incorporation of MOF particles, which facilitate the formation of fixed-size channel structures within membrane matrix. These fixed-size channels, coupled with the hydrophobic differences between the original poly(arylene ether sulfone) polymer, created a composite channel system that significantly improved the separation performance for monovalent ions, including Cl−/SO 4 2− and NO 3 −/SO 4 2−. [Display omitted] • A kind of MOF-modified cross-linked poly(arylene ether sulfone) AEM has been prepared. • The introduced cross-linked structure increases the density of AIEM. • The perm-selectivities of Cl−/SO 4 2− and NO 3 −/SO 4 2− reached 54.26 and 55.90, respectively. • The incorporation of MOFs could facilitate the formation of fixed-size channel structures. [ABSTRACT FROM AUTHOR]

A facile membrane surface modification process for improving permselectivity and antimicrobial property was proposed. A polydopamine (PDA) coating was firstly fabricated on pristine anion exchange membrane (AEM), followed by in situ reduction of Ag without adding any extra reductant. Finally, 2,5-diaminobenzene sulfonic acid (DSA) was grafted onto PDA layer via Michael addition reaction. The as-prepared AEM exhibited improved permselectivity (from 0.60 to 1.43) and effective inhibition of bacterial growth. In addition, the result of the long-term (90-h continuous electrodialysis) test expressed the excellent durability of the modified layer on membrane surface, because the concentration of Cl− and SO42− in diluted chamber fluctuated ~0.024 and 0.030 mol·L−1 with no distinct decline. The method described in this work makes the full use of multifunctional PDA layer (polymer-like coating, in situ reduction and post-organic reaction), and a rational design of functional AEM was established for better practical application. [ABSTRACT FROM AUTHOR]

The fouling mitigation of anion exchange membrane (AEM) performance is a great challenge faced by many membrane applications (e.g., electrodialysis, ED). In this study, a novel AEM is modified with dual functional layers prepared by coating hydrophilic polydopamine (PDA) on quaternized poly(2,6‐dimethyl‐1,4‐phenylene oxide), and subsequently grafting with zwitterionic structure of sulfobetaine methacrylate via the aza‐Michael reaction, aiming to improve the membrane fouling resistant. In particular, the sodium dodecyl benzene sulfonate (SDBS) is used as model foulant. The hydrophilic layer (PDA) and hydrophilic/negatively charged zwitterionic surface of AEM, act as useful barriers via physical blocking and electrostatic repulsion, respectively. The proposed modification can restrict the deposition and/or chemical adsorption of SDBS. The time elapsed until the occurrence of fouling (transition time) is significantly enhanced as result of modification (around five times longer) as evidence of the reinforced antifouling property. The enhanced performance of modified membrane is also confirmed by desalting experiments in terms of NaCl rejection potential. The facile preparation and advanced performances of dual functional layers modified AEM suggest its potential ED application. In this study, a novel anion exchange membrane is modified with dual functional layers prepared by coating hydrophilic polydopamine (PDA) on quaternized poly(2,6‐dimethyl‐1,4‐phenylene oxide), and subsequently grafting with zwitterionic structure of sulfobetaine methacrylate via the aza‐Michael reaction, aiming to improve the membrane fouling resistant. [ABSTRACT FROM AUTHOR]

[Display omitted] Ion exchange membranes (IEMs) with high monovalent-ion selectivity show promising application in ion resource recovery. In this work, we report a kind of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based on amphoteric ion exchange membranes (AIEMs) having cross-linked structure. Therein, four imidazolium-terminated aliphatic chains (2IM-nC, n = 3, 6, 9, and 12) with varied number of −CH 2 − were used as crosslinker for cross-linking membrane matrix. Small-angle X-ray scattering tests indicate that the ion cluster sizes of the four AIEMs are evaluated with values of 0.378, 0.384, 0.388 to 0.408 nm, which possibly render the enhanced mono-valent anion selectivity of as-prepared AIEMs. Tested in the electrodialysis (ED) filled with a mixture solution of 0.05 M NaCl + 0.05 M Na 2 SO 4 , at current densities of 2.5 mA·cm−2 and 5.0 mA·cm−2, the P SO 4 2 - Cl - values of cross-linked AIEM having longer alkyl chains are 20.41 and 22.51, respectively, which are higher than AIEM with shorter cross-linker alkyl chain under the same conditions (3.5). Due to the hydrophilic surface and hydrophilic/negatively charged zwitterionic surface of AIEM, act as useful barriers via physical blocking and electrostatic repulsion, respectively, the anti-fouling performance of IEMs is improved simultaneously. In view of the superior performance, it is believed that the structure–property relationship of AIEM developed here can serve as a guideline for advanced IEMs. [ABSTRACT FROM AUTHOR]

Amphoteric polyelectrolytes have been used as the materials for the high-performance ion-exchange membranes applied in redox flow battery and electrodialysis (ED) etc. In this work, four amphoteric ion-exchange membranes (AIEMs) based on sodium 1-propanesulfonate-3-methylimidazole (MIm-PS) and 1-butylimidazole (BIm) decorated poly(2,6-dimethyl-1,4-phenylene oxide) have been prepared for mono-/bi-valent anion separation by using the electrodialyzer. The optimized AIEM has a low surface area resistance of 5.79 Ω⋅cm2. During the ED testing, at 2.5 mA⋅cm−2, the perm-selectivity (P S O 4 2 − C l − ) tested in a binary mixture of 0.05 M NaCl and 0.05 M Na 2 SO 4 , achieves the value of 16.12 at 30th min, which is significantly higher than that of anion-exchange membrane (1.68) as the reference. This superior separation performance has been further verified by the perm-selectivity of 55.5, tested in a single solution of 0.05 M NaCl or 0.05 M Na 2 SO 4. The high perm-selectivity results from the electrostatic repulsion difference of mono-/bi-valent ions against the negatively-charged –SO 3 – groups, accompanying with pore-size sieving effect resulting from the smaller ion cluster space of 0.261 nm. It is interesting to find that AIEMs show the increased ion flux values of Cl−/SO 4 2−, though the presence of the negatively-charged –SO 3 − groups, which is possibly related to the convex particle-like surface that increasing the effective surface area for ions passing. This work may provide a reference to guide the architectural design of advanced monovalent anion-selective IEMs. [Display omitted] • A series of amphoteric IEMs based on decorated PPO has been prepared. • The optimized amphoteric IEMs has the low surface area resistance of 5.79 Ω cm2. • Introduction of amphoteric structures increases the surface roughness of IEMs. • The perm-selectivity (Cl−/SO 4 2−) of as-prepared AIEM outperforms the commercial AEM. • The perm-selectivity of the AIEM tested in binary mixture solution achieves 16.12. [ABSTRACT FROM AUTHOR]

In recent years, the electrodialysis (ED) technology has gained substantial attention for its role in recovering sulfuric acid from industrial wastewater. However, the typical anion exchange membranes (AEMs) have been known to exhibit notable proton leakage during ED, which can severely hinder the efficiency of acid concentration. To overcome this issue, we utilized a substrate made of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP). This choice capitalizes on the presence of fluorine-containing groups for enhanced acid stability and tertiary amine groups to minimize water content, resulting in a significant improvement in proton-blocking capabilities of the AEMs. It is worth noting that, through a combination of partial cross-linking and quaternization, these AEMs not only maintain their acid concentration performance but also substantially reduce energy consumption. Additionally, we conducted a thorough analysis of the delicate balance between current efficiency and energy consumption in acid recovery systems. In contrast to conventional AEMs and commercially available proton-blocking membranes such as ACM, we highlight the exceptional acid concentration capability (C H + = 1.28 M) and the low energy consumption (3.3 kWh/kg) of AEM-1.2. This research breakthrough marks a significant advancement in the development of acid-blocking AEMs and strongly advocates for more efficient sulfuric acid recovery from industrial wastewater. [Display omitted] • A series of acid-blocking AEMs based on PVDF-HFP has been prepared. • The as-prepared AEM was partially quaternized to reduce energy consumption. • The final concentration of AEM prepared is better than that of commercial AEM. • The problem of poor acid enrichment performance of traditional AEMs was solved. [ABSTRACT FROM AUTHOR]

• A series of AEMs based on imidazolium functionalized poly(vinyl chloride) has been prepared. • Micro-structure of PVC AEMs was tuned by the lengths of alkyl side-chains on imidazolium. • Acid blocking performance of as-prepared AEM outperforms the commercial Neosepta ACM. • The maximum concentration of H+ enriched by the optimized AEM is achieved to 1.81 M. Electrodialysis (ED) technology equipped with proton blocking anion exchange membranes (AEMs) has great potential applications in recovering acidic wastewater. To develop high performance proton-blocking AEMs, in this work, a series of imidazolium functionalized poly(vinyl chloride) (PVC) AEMs are designed. In particular, the length of alkyl side chains tethered on the imidazole compound is optimized to adjust the micro-structure of AEM. Our research demonstrates that the density of 1-butylimidazole functionalized PVC AEM matrix is enhanced, which has been proved by water uptake and thermogravimetric analysis. Hence, the acid blocking performance of optimized AEM (PVC-Im-4C) is strengthened. The maximum concentration of H+ in concentrate chamber of electrodialyser enriched by the PVC-Im-4C AEM is 1.81 M through the 24 h ED process at a current density of 20 mA·cm−2 (the initial concentration of hydrogen ions: 1.0 M). The result suggests that the optimized PVC-Im-4C AEM with long alkyl side chain on imidazole shows the excellent capacity in acid enrichment. This work should provide guidance for the follow-up design of the advanced proton blocking AEMs. [ABSTRACT FROM AUTHOR]

Recovery of sulfuric acid from industrial wastewater via electrodialysis (ED) has become a hot topic recently. Since the commercially used anion exchange membranes (AEM) generally lead to the severe proton leakage during ED process, the efficiency of the acid recovery was seriously affected. In this work, a series of proton blockage cross-linking AEM has been prepared by modifying poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF- co -HFP) with 1-vinylimidazole, followed by crosslinking with 1,4-dibromobutane. Our investigation demonstrates that the as-prepared PVDF- co -HFP-based AEM has the observable asymmetric structure on the two sides of the AEM with a smooth and dense surface and a rough and porous surface. The asymmetric structure and the hydrophobicity of the fluorinated backbone of AEM render the improved proton blocking performance, and the increased electrical efficiency and reduced energy consumption of acid recovery. For example, the optimized AEM (AEM-0.5) exhibits the acid concentration with the values of c H + = 2.04 M (initial proton concentration: 1.0 M) in concentrate cell during 12 h-ED process at current density of 20 mA cm−2 and low energy consumption of 1.75 kw·h·kg−1 relative to the commercial NEOSEPTA® AHA and proton blockage ACM AEM. It is believed that this study can provide a guideline for designing advanced proton blocking AEMs. [Display omitted] • A strategy for the preparation of crosslinked AEMs with asymmetric structure was reported. • The as-prepared AEMs show the good acid stability. • The as-prepared AEMs have potential applications in acid concentration. • The optimized AEM shows high acid concentration (2.04 M) and low energy consumption (1.75 kw·h·kg−1). [ABSTRACT FROM AUTHOR]

A kind of modified anion exchange membranes has been prepared by surface modification which enabled imparting antibacterial and anti-bacterial adhesion properties. [Display omitted] • Anion exchange membrane (L-PDA@ABS-Cl) with N-chloramine structure was synthesized by surface modification. • The L-PDA@ABS-Cl shows excellent antibacterial and anti-bacterial adhesion properties. • The difference between pristine AEM and L-PDA@ABS-Cl in desalination is slight. • The hydrophilicity was improved on the basis of little change in electrochemical performance. In this work, a series of modified anion exchange membranes (AEMs) has been prepared via self-polymerization of L-dopa on the surface of commercial AEM (Fuji I type), followed by grafting the 4-amino-benzenesulfonic acid monosodium salt (ABS) on L-polydopamine thin layer. The chemical structures of modified AEMs were confirmed by the FTIR and XPS spectra. Our investigation demonstrates that the surface resistance of the modified AEM (L-PDA@ABS-Cl) increases slightly from 1.90 Ω cm2 to 2.37 Ω cm2 and the hydrophilicity of L-PDA@ABS-Cl significantly improves, verifying by the decreased water contact angles from 86.42° to 67.25°. The difference between pristine AEM and L-PDA@ABS-Cl in desalination rates only remained less than 4% throughout the test of 240 min. The modified AEMs have the negatively charged functional layers which produce an electrostatic repulsion effect and negatively charged bacteria cannot attach to the membrane surface. As a result, L-PDA@ABS-Cl shows good performance on fouling resistance, good inhibition effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Low surface resistance and superior foul inhibition performance indicate the potential application of modified AEMs in electrodialysis (ED). [ABSTRACT FROM AUTHOR]

This review delves into the comparative analysis of nanofiltration (NF) and selective electrodialysis (S-ED) in the separation of Li+ and Mg2+ ions during lithium extraction from salt lakes. The examination is comprehensive, focusing on strategies to enhance selectivity in both methods. The paper outlines the selectivity mechanisms and then synthesizes approaches to improve the intrinsic selectivity of membranes (internal factors) and optimize process conditions (external factors). Moreover, it conducts a comparative analysis, evaluating the strengths, weaknesses, and separation efficiencies of both techniques. Comparative analyses were carried out to conclude that NF shows the higher selectivity relative to S-ED, while S-ED having a higher Li+ recovery than NF. Additionally, NF technology is more mature, due to that a variety of materials for NF membrane in the preparation process can be choosed. In contrast, the materials used for mono-/multi-valent separation cation exchange membranes (CEMs) are relatively limited, and their fabrication process requires higher precision. In conclusion, the review performs a thorough analysis and considers preparation techniques, operational conditions, and other factors on this basis. It proposes a developmental approach tailored to achieve high-selectivity Li+ recovery. [Display omitted] • Review explores selective membranes for Li extraction from salt lakes. • Review starts with selectivity principles, explores NF and S-ED improvements. • A techno-economic analysis was conducted for NF and ED. • Review clarifies membrane preparation and performance variations. [ABSTRACT FROM AUTHOR]

• A novel TiO 2 @Ag coating with photocatalysis activity on the AEM has been designed. • TiO 2 @Ag and electrochromic AEM achieve synergistic visible light photocatalysis. • The optimized AEM shows effective photocatalytic degradation and anti-biofouling activity. • Optimized AEM offers potential for sustainable water purification and desalination. Membrane-contamination during electrodialysis (ED) process is still a non-negligible challenge, while irreversible consumption and unsustainability have become the main bottlenecks limiting the improvement of anion exchange membranes (AEMs) anti-contamination activity. Here, we introduce a novel approach to design AEMs by chemically assembling 4-pyndinepropanol with bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) in an electrochromic-inspired process. Subsequently, the co-mingled TiO 2 @Ag nanosheet with the casting-solution were sprayed onto the surface of the substrate membrane to create a micrometer-thick interfacial layer. The addition of Ag nanoparticles (NPs) enhances the active sites of TiO 2 , resulting in stronger local surface plasmon resonance (LSPR) effects and reducing its energy band gap limitation (From 3.11 to 2.63 eV). Post-electrodialysis electrochromic AEMs incorporating TiO 2 @Ag exhibit synergistic enhancement of sunlight absorption, effectively suppressing photogenerated carrier binding and promoting migration. These resultant-membranes demonstrate significantly improved bacterial inhibition properties (42.0-fold increase for E. coli) and degradation activity (7.59-fold increase for rhodamine B) compared to pure TiO 2 membranes. Importantly, they maintain photocatalytic activity without compromising salt-separation performance or stability, as the spraying process utilizes the same substrate materials. This approach to rational design and regulation of anti-contamination AEMs offers new insights into the collaborative synergy of color-changing and photocatalytic materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Proton blocking anion exchange membranes (AEMs), which are employed in electrodialysis technology, show promise in acid recovery from industrial waste. A series of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) membranes were prepared using (3-aminopropyl)trimethoxysilane (APTMS) and weakly functionalized bases including N-butylimidazole (N-BuIm). Were networked to create AEMs with low leak rates. It was discovered that the appropriate concentration of siloxane crosslinker raised the membrane matrix's density and lowered the AEM matrix's hydrophilicity. Thermogravimetric measurements and water absorption have confirmed this, and the membranes in this series even swell up to 8.61 %. The maximum H+ concentration concentrated by the cross-linked AEM (BPPO/5Si) during the ED with a current density of 10 mA ∙ cm−2 was 2.35 M, which was higher than the concentration concentrated by the uncross-linked AEM (BPPO/OSi), which was 1.90 M (beginning concentration: 1.00 M). The current efficiency was 44.8 % and the energy consumption was only 1.81 kW ∙h∙kg−1. A balance between proton blocking and SO 4 2− ions transport was achieved by the optimized AEM, which exhibited increased hydrophobicity and smaller ion clusters. The improved AEM was found to have fewer ionic clusters and greater hydrophobicity. For cross-linked AEMs, a trade-off between SO 4 2− ions transport and proton blocking was thus accomplished. This work is thought to offer direction for developing sophisticated proton blocking AEMs. [Display omitted] • Imidazole-functionalized siloxane cross-linked AEMs for acid enrichment has been prepared. • (3-Aminopropyl)trimethoxysilane lowers water absorption and enables cross-linking. • The as-prepared AEM exhibits superior acid blocking performance relative to the commercial AEM. • The as-prepared AEM showcases the relatively excellent acid stability in the ED process. [ABSTRACT FROM AUTHOR]

[Display omitted] • A interfacial layer with anti-biofouling property on the AEM has been designed. • The interface layer is strengthened by bio-safety and eco-friendly agents. • The optimized AEM shows effective anti-biofilm and antibacterial activity. • High stability of the as-modified layer in electrodialysis desalination process. Strengthened surface modification via bio-safety and eco-friendly agent requirements, and the development of the antibacterial anion exchange membrane (AEM) has become crucial for resource recovery with water-sustainable management to effectively mitigate bacteria-related fouling control. A synergistic antibacterial system of lysozyme and tetrakis(hydroxymethyl)phosphonium sulfate (THPS) is explored here that is immobilized onto the surface of commercial AEM with L-dopa. Compared to the single biomacromolecule lysozyme, THPS performs a vital role in this functional layer by compensating for the insensitivity of the lysozyme to typical Gram-negative bacteria (Such as E. coli). This system demonstrated excellent antibacterial performance (E. coli and S. aureus were selected as test strains) according to the "contact-sterilization", and the change with contact time was systematically investigated. Based on confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) examination of live and dead bacteria, it was showed that the as-modified membranes by synergistic antibacterial mechanism revealed effective inhibition of biofilm growth. Moreover, these modified layers demonstrated high stability in electrodialysis (ED) desalination systems. The bio-friendly and robust anti-biofouling characteristics of this approach offer valuable insights for constructing antibacterial surfaces in similar applications. [ABSTRACT FROM AUTHOR]

Abstract Anion exchange membrane (AEMs) fouling is a serious problem influencing membrane performance during electrodialysis process(ED), which would increase power consumption and reduce water recovery. In this paper, an aliphatic anion-exchange membrane was prepared from quaternized polyvinyl alcohol (QPVA) via dual cross-linking through annealing treatment and condensation reaction to restrain the membrane water swelling. The Wu% of QPVA membrane could be reduced to 22.87 ± 0.81%. Due to the hydrophilia (59.86 ± 0.21°), negative ζ-potential surface and aliphatic matrix of QPVA, no transition time appeared under our experiment condition, indicating the QPVA membrane was scarcely fouled by SDBS. And the existence of SDBS in dilute solution generated slightly effect on the QPVA membrane resistance and only 7.47 ± 0.21% reduction of the desalination rate in ED process. Furthermore, only distilled water was used as solution or reaction media, without any harmful organic solvents, presenting an environmentally friendly route for the preparation of water-based anion-exchange membrane. So, the excellent anti-fouling performance along with green preparation of QPVA showed its remarkable prospect for desalination purpose in ED process. Graphical abstract fx1 Highlights • An aliphatic AEM (QPVA) was prepared with hydrophilia and negative ζ-potential surface. • Developed a green preparation of AEMs, using only distilled water as solution or reaction media. • The Wu% of QPVA membrane was only 22.87 ± 0.81%, far below the reported (176%). • Antifouling properties of the QPVA membrane are superior to reported membranes. [ABSTRACT FROM AUTHOR]

Biofouling is one of significant obstacles decaying the high separation performance and long-term stability of polymer membranes during the application. To explore the desirable anti-biofouling anion exchange membrane (AEM), in this work, a series of modified AEMs having surface antibacterial functional layers on surface has been prepared by using gentamicin and N-chloramine for electrodialysis (ED). The antibacterial functional layer on surface was constructed via chemical assembly. By using CuSO 4 and H 2 O 2 as the trigger, l -dopa was oxidized on surface of commercial AEM (Fuji type II) to form a carboxyl layer. Thereafter, gentamicin was chemically assembled via the amide condensation reaction. It was chlorinated with diluted NaClO solution to endow it with synergistic antibacterial activity by using gentamicin. Investigation demonstrates that the optimized membrane of P(l -Dopa)@GM-Cl has high antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Among them, flow cytometry shows that the antibacterial rate of P(l -Dopa)@GM-Cl against E. coli is more than 99%, which is much higher than original membrane (28.4%). P(l -Dopa)@GM-Cl exhibits the enhanced performance in inhibiting biofilm observed by scanning electron microscopy analysis. This work may provide a reference for the construction of anti-biofouling ion exchange membrane. [Display omitted] • An AEM with synergistic antibacterial performance was prepared via chemical assembly. • The optimized AEM shows a good resistance to chemical contamination. • The as-prepared AEM has high antibacterial rate of 99% against both E. coli and S. aureus. • Chemically assembled AEM has inhibition effect of biofilm formation. [ABSTRACT FROM AUTHOR]