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Developing highly stable electrocatalysts under industry-compatible current densities (>500 mA cm−2) in an anion-exchange membrane water electrolyzer (AEMWE) is an enormous challenge for water splitting. Herein, based on the results of density function theory calculations, a dual heterogeneous interfacial structured NiSe/Fe-Ni(OH)2 catalyst was subtly designed and successfully prepared by electrodepositing Fe-doped Ni(OH)2 on NiSe-loaded nickel foam (NF). Fe doping-driven heterogeneous structures in NiSe/Fe-Ni(OH)2 markedly boost catalytic activity and durability at industrially compatible current densities in single hydrogen and oxygen evolution reactions under alkaline conditions. In particular, NiSe/Fe-Ni(OH)2 shows a negligible performance loss at 600 mA cm−2 at least 1,000 h for overall water splitting, a distinguished long-term durability acting as AEMWE electrodes at 600 mA cm−2 and 1 A cm−2 at 85 °C for at least 95 h. Owing to Fe doping-induced strong synergetic effect between Ni and Fe, dual heterostructure-promoted charge transfer and redistribution, abundant catalytic active sites, and improvement of stability and durability, a mechanism of Fe doping-driven heterogeneous interfacial structure-promoted catalytic performance was proposed. This study provides a successful example of theory-directed catalyst preparation and pioneers a creative strategy for industry-compatible water splitting at high current density. [ABSTRACT FROM AUTHOR]

Using the method of polysulfone chloromethylation followed by quaternization, an anion-exchange membrane is synthesized for water electrolyzers with alkaline electrolyte. The characteristics of this membrane such as porosity, electrical conductivity, and gas-tightness are determined. A comparative analysis of characteristics of this membrane as compared with a porous diaphragm (analog of ZifronPerl) is carried out. The results of tests of the membrane within an alkaline electrolyzer battery are compared with the results for the porous diaphragm based on unmodified polysulfone with a hydrophilic filler (TiO2) and synthesized by phase inversion. The possible mechanism of the degradation of the main chain in quaternized polysulfone is presented. The ways are proposed for the further development of the technology of anion-exchange membranes based on polysulfone. [ABSTRACT FROM AUTHOR]

The widespread adoption of genetically modified (GM) crops has escalated concerns about their safety and ethical implications, underscoring the need for efficient GM crop detection methods. Conventional detection methods, such as polymerase chain reaction, can be costly, lab-bound, and time-consuming. To overcome these challenges, we have developed RapiSense, a cost-effective, portable, and sensitive biosensor platform. This sensor generates a measurable voltage shift (0.1–1 V) in the system's current-voltage characteristics, triggered by an increase in membrane's negative charge upon hybridization of DNA/RNA targets with a specific DNA probe. Probes designed to identify the herbicide resistance gene hygromycin phosphotransferase show a detection range from ∼1 nM to ∼10 μM and can discriminate between complementary, non-specific, and mismatched nucleotide targets. The incorporation of a small membrane sensor to detect fragmented RNA samples substantially improve the platform's sensitivity. In this study, RapiSense has been effectively used to detect specific DNA and fragmented RNA in transgenic variants of Arabidopsis, sweet potato, and rice, showcasing its potential for rapid, on-site GM crop screening. • Accelerated GM plant detection with anion exchange membrane-based nucleic acid sensor. • Improved sensitivity with small membrane sensor integration to detect fragmented RNA. • The RapiSense prototype device is easy-to-operate, portable, and time-efficient. [ABSTRACT FROM AUTHOR]

This research focused on the development of anion exchange membrane electrolytes suitable for direct methanol alkaline fuel cells (DMAFC) by employing a straightforward blending and solution casting process complemented by subsequent heat treatment. Tartaric acid (TA) was employed as a cross‐linking agent to enhance the heat resistance and structural integrity of the PVA matrix. The distinctive attributes of the PT (PVA and tartaric acid blend) samples, including water absorption and swelling capacity, were comprehensively investigated with respect to variations in both TA content (expressed as wt. % relative to the PVA matrix) and alterations in the duration of thermal treatment. Cross‐link formation between the polymer chains and TA was determined using FTIR analysis. The samples were subjected to comprehensive analysis, encompassing the determination of crystallinity via X‐ray diffraction (XRD), assessment of thermal stability using thermogravimetric analysis (TGA), investigation of morphology through scanning electron microscopy (SEM), and measurement of ionic conductivity using AC Impedance spectroscopy. The methanol permeability was measured to determine the selectivity values of the membranes. Subsequently, within the DMAFC system, the performances of the PT30‐3, PT40‐2, and PT40‐3 membranes, which exhibited the highest selectivities, were assessed. The contribution of the crosslinking process to the resistance of the membranes to oxidative conditions, as represented by the Fenton solution, was evaluated to assess the chemical stability of the membranes. The maximum power densities for PT30‐3 and PT40‐3 membranes reached 15.29 and 12.53 mW/cm2 at 30°C, respectively. These figures exhibited a notable increase, reaching 32.73 mW/cm2 for PT30‐3 and 31.72 mW/cm2 for PT40‐3 when the temperature was elevated to 60°C. This study confirmed that the crosslinking strategy using TA assisted by thermal treatment is very simple and competitive compared with other techniques reported in the literature. PT membranes are promising candidates for commercialization and utilization in DMAFC owing to their environment‐friendly nature, cost‐effectiveness, and high efficiency. Highlights: TA cross‐linking improved the thermal and dimensional stability of PVA.The PT membrane properties varied with TA content and thermal treatment time.Some electrolytes in this study outperformed those previously reported for DMAFC.PT membranes offer efficiency, cost‐effectiveness, and eco‐friendliness for DMAFCs. [ABSTRACT FROM AUTHOR]

The present study looked into a sustainable approach for synthesizing sodium ion conducting cation exchange membrane, in addition to addressing the methanol permeability, ionic conductivity, and cost of the direct methanol fuel cell (DMFC). The polyvinyl alcohol (PVA)-based sodium ion conducting membranes were synthesized by the sustainable modified phase inversion technique using a green nonsolvent coagulation bath composed of sodium hydroxide and sodium sulfate. Alkaline medium operating sulfonated polyvinyl alcohol (SPVA)-montmorillonite clay (MMT) was developed to overcome the drawbacks of a proton exchange membrane working in an acidic medium and an anion exchange membrane used in an alkaline medium. The SPVA-MMT membrane exhibited ionic conductivity of 0.0751 S cm−1 due to the presence of inorganic salts in the coagulation bath and the cation exchange capacity of the clays. Passive alkaline DMFC studies conducted using SPVA-MMT membrane showed a peak power density of 7.51 mW cm−2 at ambient conditions. • Green membrane synthesis technique to produce clean energy. • The green synthesis technique reduces the risk of human repro-toxicity. • A green non-solvent coagulation bath and clay enhance the Na+ ion conductivity. • Composite membrane shows ionic conductivity of 0.0751 S cm−1 at ambient conditions. • A 62.90% increase in power density as compared to Nafion 117/Na+ membrane. [ABSTRACT FROM AUTHOR]

The article is devoted to the development of a new-generation elemental base for aqueous alkaline electrolyzers with anion-exchange membranes. Two new membranes and various types of electrodes are proposed, which significantly increase the purity of the generated electrolysis gases and the operating outlet pressure directly at the outlet of the electrolysis module, while maintaining low specific energy consumption. The electrolysis module consists entirely of membrane–electrode assemblies. Their composition includes components tested in the industrial alkaline electrolysis; they stand out from the known analogues in their chemical resistance. Various types of catalysts that can be used as part of membrane–electrode assemblies are considered. The results of express tests of the 12Kh18N10T-stainless-steel electrodes revealed the oxidation process of chromium, a part of the alloy, which is shown to lower its corrosion resistance. When testing electrodes based on a steel mesh coated with a protective nickel layer, an extensive anode pitting corrosion was detected during its operating at high current densities. As an alternative, nickel-mesh electrodes are proposed. They showed excellent corrosion resistance and high adhesion of the electrodeposited catalysts. Catalytic coatings consisting of nickel or nickel–cobalt powder with chemically deposited phosphorus are investigated as catalysts. [ABSTRACT FROM AUTHOR]

Anion-exchange membranes (AEMs) are involved in a wide range of applications, including fuel cells and water electrolysis. A straightforward method for the preparation of efficient AEMs consists of polymer functionalization with robust anion-exchange sites. In this work, an aliphatic polyketone was functionalized with 1-(3-aminopropyl)imidazole through the Paal–Knorr reaction, with a carbonyl (CCO %) conversion of 33%. The anion-exchange groups were generated by the imidazole quaternization by using two different types of alkyl halides, i.e., 1,4-iodobutane and 1-iodobutane, with the aim of modulating the degree of crosslinking of the derived membrane. All of the membranes were amorphous (Tg ∼ 30 °C), thermally resistant up to 130 °C, and had a minimum Young's modulus of 372 ± 30 MPa and a maximum of 86 ± 5 % for the elongation at break for the least-crosslinked system. The ionic conductivity of the AEMs was determined at 25 °C by electrochemical impedance spectroscopy (EIS), with a maximum of 9.69 mS/cm, i.e., comparable with that of 9.66 mS/cm measured using a commercially available AEM (Fumasep-PK-130). Future efforts will be directed toward increasing the robustness of these PK-based AEMs to meet all the requirements needed for their application in electrolytic cells. [ABSTRACT FROM AUTHOR]

This study presents the possibility of using diffusion dialysis for the separation of inorganic acids (hydrochloric, nitric, and hydrofluoric) and their ferric salts whose composition corresponds to that of real spent pickling solutions. At a steady state, the transport properties of three different anion-exchange membranes (Fumasep-FAD, Neosepta-AFN, and Neosepta-AHA) are compared using a continuous counter-current dialyzer. At a constant composition of the solutions (acid concentration 3 mol L−1 and iron concentration 30–40 g L−1), the effects of volumetric liquid flow rates on the transport rate of H+ and Fe3+ ions through the membrane are studied. The dialysis process is characterized by the recovery of acids and the rejection of salts. Furthermore, the values of the dialysis coefficients of acids, iron, and the acid/iron separation factors are calculated and compared. The volumetric flow rates of the inlet streams change in limits from 3 × 10−8 to 6 × 10−8 m3 s−1 (from 3 to 6 L h−1 m−2, relative to the membrane area). A comparison of the tested membranes shows slightly better results for acid recovery, iron rejection, and acid/iron separation factors for the Fumasep-FAD membrane than for the Neosepta-AFN membrane. However, the results obtained show that both of these anion-exchange membranes can be considered good separators for tested mixtures that simulate real spent pickling solutions, and there is a good precondition for using diffusion dialysis for processing these solutions in industrial practice. On the contrary, very low values of acid recovery and the overall dialysis coefficient of acid are found for the Neosepta-AHA membrane in the test range of the volumetric flow rate, and, thus, this membrane is insufficient for the adequate separation of these acids and iron salts.

The potential of application of an electrospun nanofiber sheet as new polymeric support for immobilizing the liquid membrane, instead of a common commercial polypropylene sheet, in on-chip electromembrane extraction (EME) of some acidic polar drugs followed by HPLC with ultraviolet detection is presented. The nanofiber sheet was prepared by electrospinning a mixture of polycaprolactone and polyaniline. The successful synthesis of the electrospun nanofiber sheet was confirmed by field emission-scanning electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, and atomic force microscopy. Several parameters affecting the efficiency of the microextraction method, including pHs of the donor and acceptor phases, applied voltage, sample flow rate, phosphate content of the acceptor phase, and sample volume, were investigated and optimized. After optimization, the linearity range of 0.5–250.0 µg L−1 and detection limits of 0.2–1.0 µg L−1 were obtained for the analytes. The extraction recovery values and preconcentration factors were 10.7–55.3% and 16–83, respectively. The presence of polyaniline in the composition of the nanofibers significantly improved the extraction efficiency of the polar acidic drugs due to providing the possibility of various interactions with the target analytes such as hydrogen bonding, π-stacking, and anion exchange. The obtained results demonstrate the excellent efficiency of the synthesized electrospun nanofibrous mat as a novel support membrane for immobilizing 1-octanol and as an interactive substrate for electromembrane extraction of acidic polar drugs. Eventually, the proposed on-chip EME method exhibits acceptable precision (relative standard deviations less than 9.7% (n = 3)) and good accuracy (86–112%) for determining the target analytes in the plasma samples. [ABSTRACT FROM AUTHOR]

An experimental laboratory set of samples of composite heterogeneous anion-exchange membranes was obtained by us for the development of our original method of polycondensation filling. Anion-exchange membranes were prepared on plasma-treated and non-plasma-treated polyester fiber fabrics. The fabric was treated with low-temperature argon plasma at a power of 400 W for 10 min at a pressure of 5 × 10−5 mbar. On the surface and bulk of the polyester fiber, a polyfunctional anionite of mixed basicity was synthesized and formed. The anion-exchange membrane contained secondary and tertiary amino groups and quaternary ammonium groups, which were obtained from polyethylene polyamines and epichlorohydrins. At the stage of the chemical synthesis of the anion matrix, oxidized nanoparticles (~1.5 wt.%) of silicon, nickel, and iron were added to the monomerization composition. The use of ion-plasma processing of fibers in combination with the introduction of oxidized nanoparticles at the synthesis stage makes it possible to influence the speed and depth of the synthesis and curing processes; this changes the formation of the surface morphology and the internal structure of the ion-exchange polymer matrix, as well as the hydrophobic/hydrophilic balance and—as a result—the different operational characteristics of anion-exchange membranes.

Poly(styrene-b-(ethylene-co-butylene)-b-styrene) copolymer (SEBS) has been widely used for anion exchange membranes (AEMs). However, it is still challenging to improve the dimensional stability of SEBS based AEMs because their main component poly(ethylene-co-butylene) phase (PEB) is rubbery. To this end, chemical crosslinking is widely built within the polystyrene phase (PS), but which still makes the PEB phase contribute nothing to the dimensional stability and ionic conductivity. Herein, we attempt to synthesize poly(styrene-b-butadiene-b-styrene) copolymers (SBS) owning adjustable content of 1,4-butadiene units via living anionic polymerization, following with hydrogenation. As more 1,4-butadiene units are copolymerized into SBS, the PEB phase becomes even harder, which significantly enhances the comprehensive performance of AEMs. The AEMs intentionally maximized by this approach not only have ultrahigh dimensional stability (i.e. 23.2 ± 0.1 of WU, 3.8 ± 0.1 of SR at 30 °C, nearly no change within 30 ~ 80 oC), but also exhibit a comparable hydroxide conductivity (~ 85 mS cm−1 at 80 °C with IEC as 1.06 ± 0.05 mmol/g). The membrane electrode assembly made from such AEM has a peak power density 370 mW cm−2 at a current density of 800 mA cm−2. This work provides a straightforward approach for fabricating long term alkaline durable and mechanically stable SEBS based AEMs, suitable for fuel cells application. [ABSTRACT FROM AUTHOR]

Redox flow batteries are the most promising large‐scale energy storage technologies for solving intermittency issues of renewable energy sources such as wind, solar, etc. They have favorable features over other battery technologies like high energy efficiency, intrinsic safety, independent scaling, and a long lifetime. Among various RFBs, all‐Iron redox flow batteries are an attractive choice because iron is the second most abundant metal in earth's crust, is cheap and ecofriendly. However, low charging efficiency, parasitic hydrogen evolution reaction (HER) at the negative Fe/FeII electrode, self‐discharge by electrolyte cross‐over, and poor cycle‐life (due to ferric hydroxide precipitation) are the major technical challenges to be overcome for the successful commercialization of all‐iron redox flow batteries. Herein, we report an all‐iron redox flow battery containing Fe/FeII and FeIII/FeII redox couples separated by a self‐made anion exchange membrane. We also examined the impact of adding ZnII ions on the electrochemical performance of the Fe/FeII redox couple. The coulombic efficiency, voltage efficiency and energy efficiency of the cell with 0.03 m ZnCl2 was found to be greater (90 %, 70.96 % and 63.86 %) than those of the cell without ZnCl2 (80 %, 62.06 % and 49.64 %). The results reveal that the addition of small amounts of ZnII ions to the Fe/FeII electrode suppresses the hydrogen evolution reaction and increase the cell performance. [ABSTRACT FROM AUTHOR]

The hydrogen economy relies on effective and environmentally friendly processes for energy conversion and storage. To this end, hydrogen is progressively holding the role of preferred energy vector. Within this frame, electrochemical science and technology is actively contributing in developing advanced fuel cells and water electrolyzers to be integrated in (i) energy parks to decouple production and consumption; (ii) exploit renewable sources; (iii) favour the progressive reduction of fossil fuels and reduce the greenhouse effect via decarbonization. The exploitation of the relevant processes and devices call for the sound control over the environmental impact from production to end-of-life steps. Here, life-cycle analyses were performed and discussed focusing on both acid and alkaline fuel cells, i.e., proton exchange membrane fuel cells (PEMFC) and anion-exchange membrane fuel cells (AEMFC), and assessing their contribution to key environmental impact categories such as, for example, global warming and ozone layer depletion. Within these premises, the study points to the benefits of replacing platinum by low load Pd/CeO2 bifunctional electrocatalyst on electrochemical hydrogen production and usage.

Developing an inexpensive green method for preparing membranes is crucial to reduce the cost of electrodialysis (ED). Introducing cationic functional groups into the main polymer chain of anion-exchange membranes (AEMs) is a common approach for modifying AEM materials, despite involving complex chemical processes. This study employs various cationic surfactants as functional materials, PVP as a hydrophilic agent, and polyether sulfone as the skeleton material to prepare AEMs using a simple procedure. The evaluated cationic surfactants have identical quaternary ammonium groups but different lengths of hydrophobic alkyl chains. The internal structures of the resulting AEMs are regulated by the compounding effects between the PVP and surfactants with distinct alkyl chains. The prepared AEMs were integrated into an ED system to evaluate their performance in the (i) desalination of brackish water, (ii) desalination of salt solutions containing organic matter, and (iii) removal of phenol from phenolic solutions. All AEMs exhibited good membrane-forming properties, although that prepared with hexadecyltrimethylammonium chloride as the functional material achieved the best overall performance. Overall, this report describes a simple and green method for preparing AEMs that can efficiently separate salts from organic solutions. [Display omitted] • A simple and green method for preparing AEMs was designed in this work. • The internal structure of AEMs can be well regulated. • AEMs were stably used in ED for the desalination of brackish water. • AEMs showed good feasibility in separating salts from organic solution efficiently. [ABSTRACT FROM AUTHOR]

Anion-exchange membranes (AEMs) are involved in a wide range of applications, including fuel cells and water electrolysis. A straightforward method for the preparation of efficient AEMs consists of polymer functionalization with robust anion-exchange sites. In this work, an aliphatic polyketone was functionalized with 1-(3-aminopropyl)imidazole through the Paal–Knorr reaction, with a carbonyl (CCO %) conversion of 33%. The anion-exchange groups were generated by the imidazole quaternization by using two different types of alkyl halides, i.e., 1,4-iodobutane and 1-iodobutane, with the aim of modulating the degree of crosslinking of the derived membrane. All of the membranes were amorphous (Tg ∼ 30 °C), thermally resistant up to 130 °C, and had a minimum Young’s modulus of 372 ± 30 MPa and a maximum of 86 ± 5 % for the elongation at break for the least-crosslinked system. The ionic conductivity of the AEMs was determined at 25 °C by electrochemical impedance spectroscopy (EIS), with a maximum of 9.69 mS/cm, i.e., comparable with that of 9.66 mS/cm measured using a commercially available AEM (Fumasep-PK-130). Future efforts will be directed toward increasing the robustness of these PK-based AEMs to meet all the requirements needed for their application in electrolytic cells.

As highlighted by the recent roadmaps from the European Union and the United States, water electrolysis is the most valuable high‐intensity technology for producing green hydrogen. Currently, two commercial low‐temperature water electrolyzer technologies exist: alkaline water electrolyzer (A‐WE) and proton‐exchange membrane water electrolyzer (PEM‐WE). However, both have major drawbacks. A‐WE shows low productivity and efficiency, while PEM‐WE uses a significant amount of critical raw materials. Lately, the use of anion‐exchange membrane water electrolyzers (AEM‐WE) has been proposed to overcome the limitations of the current commercial systems. AEM‐WE could become the cornerstone to achieve an intense, safe, and resilient green hydrogen production to fulfill the hydrogen targets to achieve the 2050 decarbonization goals. Here, the status of AEM‐WE development is discussed, with a focus on the most critical aspects for research and highlighting the potential routes for overcoming the remaining issues. The Review closes with the future perspective on the AEM‐WE research indicating the targets to be achieved. [ABSTRACT FROM AUTHOR]

Summary: Anion‐exchange membrane direct formate fuel cells (AEM DFFCs) were fabricated and tested at various fuel and electrolyte concentrations ranging from 1 to 5 M, flow rates ranging from 1 to 5 mL/min, and cell temperatures ranging from room temperature to 60°C with varying Nafion ionomer contents in the anode. A mixture of potassium formate (HCOOK) and potassium hydroxide (KOH) was fed into the serpentine anolyte flow field, while the air was forced into the serpentine air flow field at 100 sccm. The results revealed that feeding DFFCs with an anolyte solution containing 3‐M HCOOK in 3‐M KOH yielded the best cell output, compared to using an anolyte solution containing higher fuel and electrolyte concentrations. According to an empirical model investigation of the AEM DFFCs performance, reducing the Nafion ionomer content induced a rise in the exchange current density and the fuel crossover equivalent current density but resulted in a drop in the DFFCs' area‐specific resistance. In this investigation, the optimum Nafion ionomer content in the anode was 1.87 mg/cm2. The maximum power density of the DFFCs tested at ambient temperature and 60°C were 94.78 mW/cm2 and 115.3 mW/cm2, respectively, as the AEM DFFCs were fed with anolyte containing 3‐M HCOOK in 3‐M KOH at 5 mL/min with anode Nafion ionomer content of 1.87 mg/cm2. [ABSTRACT FROM AUTHOR]

About two thirds of global greenhouse emissions is caused by burning of fossil fuels for energy purposes and this has spurred great research interest to develop renewable energy technologies based on wind, solar power, and so on. Redox flow batteries (RFB) are receiving wide attention as scalable energy‐storage systems to address the intermittency issues of renewable energy sources. However, for widespread commercialization, the redox flow batteries should be economically viable and environmentally friendly. Zinc based batteries are good choice for energy storage devices because zinc is earth abundant and zinc metal has a moderate specific capacity of 820 mA hg−1 and high volumetric capacity of 5851 mA h cm−3. We herein report a zinc‐iron (Zn‐Fe) hybrid RFB employing Zn/Zn(II) and Fe(II)/Fe(III) redox couples as positive and negative redox systems, respectively, separated by a self‐made anion exchange membrane (AEM). The battery delivers a good discharge voltage of approximately 1.34 V at 25 mA cm−2, with a coulombic efficiency (CE) of 92%, voltage efficiency (VE) of 85% and energy efficiency (EE) of ~78% for 30 charge‐discharge cycles. Repeated galvanostatic charge/discharge cycles show no degradation in performance, confirming the excellent stability of the system. A key advancement in the present Zn‐Fe hybrid redox flow battery with AEM separator is that no dendrite growth was observed on zinc electrode on repeated charge‐discharge cycles, which was the serious drawback of many previously reported zinc based redox flow batteries. [ABSTRACT FROM AUTHOR]

Oxidation of primary alcohol to the corresponding aldehyde remains a significant challenge, even with the state‐of‐the‐art chemistry. Here, a novel electrochemical system was developed for the exclusive production of aldehyde from primary alcohol using an anion‐exchange membrane (AEM) reactor. Oxidation proceeded on a gold catalyst under basic conditions, which largely enhanced the reaction rate. Despite the basic nature around the reaction sites, the oxidation of primary alcohols exclusively yielded the corresponding aldehyde, which was attributed to the unique three‐phase interfacial reaction sites in the AEM reactor. In addition to benzyl alcohol, the oxidation of allylic and aliphatic alcohols was also demonstrated. Comparison of constant potential electrolysis with the AEM reactor or a conventional batch‐type cell revealed the crucial role of the triple‐phase boundary for the selectivity of the oxidation of alcohol. [ABSTRACT FROM AUTHOR]

Recycling spent lithium-ion batteries (LIBs) to efficient water-splitting electrocatalysts is a promising and sustainable technology route for green hydrogen production by renewables. In this work, a fluorinated ternary metal oxide (F-TMO) derived from spent LIBs was successfully converted to a robust water oxidation catalyst for pure water electrolysis by utilizing an anion-exchange membrane. The optimized catalyst delivered a high current density of 3.0 A cm -2 at only 2.56 V and a durability of >300 h at 0.5 A cm -2 , surpassing the noble-metal IrO 2 catalyst. Such excellent performance benefits from an artificially endowed interface layer on the F-TMO, which renders the exposure of active metal (oxy)hydroxide sites with a stabilized configuration during pure water operation. Compared to other metal oxides (i.e., NiO, Co 3 O 4 , MnO 2 ), F-TMO possesses a higher stability number of 2.4 × 10 6 , indicating its strong potential for industrial applications. This work provides a feasible way of recycling waste LIBs to valuable electrocatalysts.

This article presents the possibility of using diffusion dialysis for processing spent pickling solution from pickling stainless steels with a mixture of nitric acid and hydrofluoric acid. A counter-current two-compartment dialyzer equipped with an anion-exchange membrane Neosepta-AFN was used to study and compare the diffusion dialysis of model mixture of hydrofluoric acid and ferric nitrate and a real spent pickling solution. The separation efficiency was characterized by the acid recovery yield, the rejection coefficient of the metals, the permeability coefficient of the membrane, and the separation factor. These characteristics were calculated from the data obtained at steady state. For the real spent pickling solution tested, the permeability values of nitrates 1.7 × 10−6 m s−1, fluorides 0.4 × 10−6 m s−1, and ferric ions 1.1 × 10−7 m s−1 were achieved. The separation factor for nitrates/ferric ions was 15.7 and 3.6 for fluorides/ferric ions. Furthermore, the dependencies of recovery yield and rejection for different concentrations of hydrofluoric acid and ferric nitrate were determined.

The hydrogen economy relies on effective and environmentally friendly processes for energy conversion and storage. To this end, hydrogen is progressively holding the role of preferred energy vector. Within this frame, electrochemical science and technology is actively contributing in developing advanced fuel cells and water electrolyzers to be integrated in (i) energy parks to decouple production and consumption; (ii) exploit renewable sources; (iii) favour the progressive reduction of fossil fuels and reduce the greenhouse effect via decarbonization. The exploitation of the relevant processes and devices call for the sound control over the environmental impact from production to end-of-life steps. Here, life-cycle analyses were performed and discussed focusing on both acid and alkaline fuel cells, i.e., proton exchange membrane fuel cells (PEMFC) and anionexchange membrane fuel cells (AEMFC), and assessing their contribution to key environmental impact categories such as, for example, global warming and ozone layer depletion. Within these premises, the study points to the benefits of replacing platinum by low load Pd/CeO2 bifunctional electrocatalyst on electrochemical hydrogen production and usage. [ABSTRACT FROM AUTHOR]

A comparative analysis of mass transfer characteristics and energy consumption was carried out for the electrodialysis recovery of PV from of NaH2PO4 solutions and multicomponent (0.045 M NaxH(3−x)PO4, 0.02 M KCl, 0.045 M KOH, 0.028 M CaCl2, and 0.012 M MgCl2, pH 6.0 ± 0.1) solution in conventional continuous current (CC) and pulsed electric field (PEF) modes. The advantages of using PEF in comparison with CC mode are shown to increase the current efficiency and reduce energy consumption, as well as reduce scaling on heterogeneous anion-exchange membranes. It has been shown that PEF contributes to the suppression of the “acid dissociation” phenomenon, which is specific for anion-exchange membranes in phosphate-containing solutions. Pulse and pause lapse 0.1 s–0.1 s and duty cycle 1/2 were found to be optimal among the studied PEF parameters.

The influence of the nature of amine solutions on the frequency spectrum of the electrochemical impedance of the bipolar membrane aMB-2m is investigated. Moreover, the effect of the circulation rate of solutions in the electrodialyzer chambers on the volt-ampere characteristics of the Ralex AMH and MA-40L anion-exchange membranes and the aMB-2m bipolar membrane has been investigated. The diffusion characteristics of various types of anion-exchange membranes in a system containing dimethylammonium sulfate ((DEA)2H2SO4), as well as the diffusion characteristics of the Ralex AMH membrane in systems with methylammonium sulfate, dimethylammonium sulfate, diethylammonium sulfate, and ethylenediammonium sulfate ((MA)2H2SO4, (DMA)2H2SO4, (DEA)2H2SO4, EDAH2SO4) have been studied. It is shown that diffusion permeability depends on the structure and composition of anion-exchange membranes, as well as on the nature of amines. The technical and economic characteristics of the electromembrane processes for the production of amines and sulfuric acid from amine salts are determined. It is shown that when using Ralex AMH anion-exchange membranes in an electrodialyzer together with bipolar aMB-2m membranes, higher concentrations of diethylamine and sulfuric acid are achieved, compared with the use of MA-40L anion-exchange membranes.

Anion-exchange membranes modified with a polyquaternium-22 (PQ-22) polymer were studied for their use in electrodialysis. The use of PQ-22 for modification makes it possible to “replace” weakly basic amino groups on the membrane surface with quaternary amino groups. It was found that the content of quaternary amino groups in PQ-22 is higher than the content of carboxyl groups, which is the reason for the effectiveness of this polymer even when modifying Ralex AHM-PES membranes that initially contain only quaternary amino groups. In the case of membranes containing weakly basic amino groups, the PQ-22 polymer modification efficiency is even higher. The surface charge of the modified MA-41P membrane increased, while the limiting current density on the current-voltage curves increased by more than 1.5 times and the plateau length decreased by 2.5 times. These and other characteristics indicate that the rate of water splitting decreased and the electroconvective mixing at the membrane surface intensified, which was confirmed by direct visualization of vortex structures. Increasing the surface charge of the commercial MA-41P anion-exchange membrane, reducing the rate of water splitting, and enhancing electroconvection leads to mitigated scaling on its surface during electrodialysis.

[Display omitted] • Dense PSS and PDADMA saloplastics are prepared via a simple hot-press approach. • These saloplastics function as anion-exchange membranes. • Water uptake, resistance ion exchange capacity comparable to commercial membranes. • Long term stability (up to 60 days) observed in extreme alkaline and acidic conditions. • The membranes show relevant monovalent selectivity for chloride over sulphate ions. Polymeric ion-exchange membranes have come a long way since their invention, benefiting a wide range of processes, ranging from desalination to fuel cells. However, challenges such as alkaline stability, monovalent ion selectivity, cost-effectivity, and process sustainability largely persist. This work showcases alkaline stable anion-exchange membranes made by hot-pressing of a polyelectrolyte complex of poly(styrenesulfonate) (PSS) and poly(diallyldimethylammonium) (PDADMA). This completely aqueous production approach leads to especially dense (non-porous) saloplastic films with an excess of cationic groups, demonstrating good stability even at high salinities (up to 2 M NaCl). On key performance indicators for anion exchange membranes, such as water uptake (~40%), permselectivity (up to 97%), ion exchange capacity (1.01 mmol g−1), and resistance (2.3 O·cm2) the membranes show comparable values to commercial membranes. A drop in permselectivity at high salinities, however, indicates that the charge density of the membranes could be further improved. Still, what really sets these membranes apart is their natural long term (up to 60 days) stability at extreme acidic (pH 0) and alkaline conditions (pH 14) and a relevant monovalent selectivity of up to 6.3 for Cl− over SO 4 2−. Overall this work showcases PDADMA/PSS based saloplastics as highly promising and stable anion-exchange membranes, that can be produced by a simple, scalable, and sustainable approach. [ABSTRACT FROM AUTHOR]

The simultaneous removal of nitrate and nitrite from water was investigated in this study using the Donnan dialysis. First, as a preliminary study, the removal of one component in the feed compartment was performed considering different parameters such as the concentration of counter-ion in the receiver compartment, concentration of nitrate and concentration of nitrite separately in the feed compartment. Then, the removal of nitrate and nitrite simultaneously in the feed compartment was conducted through three membranes, namely AFN, AMX and ACS. The membrane that displayed the most advantageous properties in the exchange is the one that provided the highest rate of counter-ion transport from the receiver to the feed; that has been afterwards used in the optimization according to the Response Surface Methodology. [ABSTRACT FROM AUTHOR]

Electrodialysis is widely used to separate and concentrate sulfuric acid from industrial wastewater. Nevertheless, owing to the proton leakage of anion‐exchange membrane (AEM), the concentration of recycled sulfuric acid is typically less than 20 wt.%. What is more, the restraining of proton leakage would sacrifice the conductivity of membrane, leading to the increasing of energy consumption (EC). In this work, a proton block and highly conductive polyaniline (PANI)/polyvinylidene fluoride (PVDF) membrane were prepared by creating PANI dominated and hydrophobicity ion channels through etching. The variations of solubility, structure, and electrical performance of membrane during etching process were investigated. As a result, the electrical performance of membrane, especially for the conductivity, was significantly improved owning to the formation of PANI dominated ion channels and spaces. Meanwhile, even the porosity and water content of etched membrane were improved, the anions were mainly migrated through molecular chains of PANI; the protons were still blocked by the hydrophobic pores. Further, the etched membranes with different porosities were used to enrich sulfuric acid (1 wt.%) through electrodialysis. As a result, the proton leakage was proved to be the major limitative factor of acid solution enrichment. By using the optimal etched membrane, concentrated acid (41 wt.%) was obtained with a less energy consume (EC), compared with commercial AEM. [ABSTRACT FROM AUTHOR]

The availability of durable, high-performance electrocatalysts for the hydrogen oxidation reaction (HOR) is currently a constraint for anion-exchange membrane fuel cells (AEMFCs). Herein, a rapid microwave-assisted synthesis method is used to develop a core-shell catalyst support based on a hydrogenated TiO 2 /carbon for PtRu nanoparticles (NPs). The hydrogenated TiO 2 provides a strong metal-support interaction with the PtRu NPs, which improves the catalyst's oxophilicity and HOR activity compared to commercial PtRu/C and enables greater size control of the catalyst NPs. The as-synthesized PtRu/TiO 2 /C-400 electrocatalyst exhibits respectable performance in an AEMFC operated at 80 °C, yielding the highest current density (up to 3× higher) within the catalytic region (compared at 0.80-0.90 V) and voltage efficiency (68%@ 0.5 A cm -2 ) values in the compared literature. In addition, the cell demonstrates promising short-term voltage stability with a minor voltage decay of 1.5 mV h -1 . This "first-of-its-kind in alkaline" work may open further research avenues to develop rapid synthesis methods to prepare advanced core-shell metal-oxide/carbon supports for electrocatalysts for use in the next-generation of AEMFCs with potential applicability to the broader electrochemical systems research community., (© 2023 The Authors. Small published by Wiley‐VCH GmbH.)

The development of the most effective, suitable and economic ion-exchange membranes is crucial for reverse electrodialysis (RED)—the most widely studied process to harvest salinity gradient energy from mixing seawater and river water. RED utilizes two types of membranes as core elements, namely cation exchange membranes (CEM) and anion exchange membranes (AEM). Since the preparation of AEMs is more complex compared to CEMs, the design and development of anion exchange membranes have been the focus in this study. Homogeneous AEMs based on two types of polyepichlorohydrin (PECH) with different chlorine amounts (PECH-H, 37 wt% and PECH-C, 25 wt%) were synthesized, and first-time benchmarking of the membrane properties was conducted. In addition to physicochemical membrane properties, some instrumental analyses such as SEM, FTIR and DSC were investigated to characterize these anion-exchange membranes. Based on the results, although the PECH-H-type membrane had enhanced ion-exchange properties, PECH-C-based anion-exchange membranes exhibited a higher power density of 0.316 W/m2 in a lab-scale RED system. Evidently, there is room for the development of new types of PECH-C-based AEMs with great potential for energy generation in the RED process.

Visualization of electroconvective (EC) vortices at the undulated surface of an AMX anion-exchange membrane (Astom, Osaka, Japan) was carried out in parallel with the measurement of chronopotentiograms. Weak polybasic acid salts, including 0.02 M solutions of tartaric (NaHT), phosphoric (NaH2PO4), and citric (NaH2Cit) acids salts, and NaCl were investigated. It was shown that, for a given current density normalized to the theoretical limiting current calculated by the Leveque equation (i/ilimtheor), EC vortex zone thickness, dEC, decreases in the order NaCl > NaHT > NaH2PO4 > NaH2Cit. This order is inverse to the increase in the intensity of proton generation in the membrane systems under study. The higher the intensity of proton generation, the lower the electroconvection. This is due to the fact that protons released into the depleted solution reduce the space charge density, which is the driver of EC. In all studied systems, a region in chronopotentiograms between the rapid growth of the potential drop and the attainment of its stationary values corresponds to the appearance of EC vortex clusters. The amplitude of the potential drop oscillations in the chronopotentiograms is proportional to the size of the observed vortex clusters.

Electroconvection is the principal mechanism that allows markedly increasing the rate of ion transfer through ion-exchange membranes in intensive current regimes. In this work, we investigated the possibility of intensifying electroconvection in solution near heterogeneous MA-41 anion-exchange membrane (Shchekinoazot production) by the modifying of its surface. The use of weakly crosslinked ion-exchange resin (MA-41P) in the course of the membrane manufacturing, with subsequent chemical modification of its surface (MA-41PM), is shown to make it possible to increase the limiting current density almost twice. The value of the reduced potential drop (after subtracting the ohmic contribution), at which significant generation of H+ and OH– ions begins, is shifted from 0.8 V in the case of MA-41 to 1.7 V in the case of MA-41PM. The current density related to the onset of water splitting is equal to 0.9 in the case of MA-41; 2 in the case of MA-41PM (where is the theoretical value of the limiting current density). The special feature of the modified membrane behavior is the presence of a range of potential drop (between 50 and 80 mV in the reduced scale), in which the system with the MA-41PM has negative differential resistance: in this range, the potential drop decreases when the current density increases. This behavior occurs when measuring quasi-stationary I–V curves; correspondingly, in the chronopotentiogram there is a time interval, where the potential drop decreases with time. The electroconvection is intensified near a modified membrane due to a higher fraction of conductive areas on the surface of the modified membrane and the redistribution of these areas via formation of their agglomerates in the centers of the cells formed by the reinforcing mesh. Mathematical modeling shows the concentration polarization of the modified membrane being less than that of the pristine one. Meanwhile, the structure of electroconvective vortices is optimized: the vortices near the modified membrane are larger; they do not extinguish each other, unlike the case of MA-41. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cl was doped into the lattice of LiCoO 2-x Cl x ultrathin nanosheet by alkaline molten salt method. • The electron distribution is optimized to enhance the covalence of Co-O by Cl doping. • The deep delithiation of LiCoO 2-x Cl x to produce O 2 2 intermediates is inclined to be LOM. • Lattice doping of Cl- increases the efficiency of LiCoO 2 in AEM water electrolyzers. LiCoO 2 is a kind of promising electrocatalyst for oxygen evolution reaction (OER), while it is difficult to successfully achieve the nanosheets morphology of LiCoO 2 with regulated electronic configuration and optimal reaction pathway. Here, we demonstrate that doping Cl ion into the lattice of LiCoO 2-x Cl x ultrathin nanosheets by alkaline molten salt method can bring out dual roles, which not only adjust the covalency of Co-O bond to improve OER activity, but also promote the leaching of Li to activate lattice oxygen. The deep delithiation of LiCoO 2-x Cl x to produce O 2 2– intermediates is inclined to be lattice oxygen mediated mechanism (LOM). The more oxygen vacancies due to the accurate lattice doping of optimized Cl- regulate the coordination environment and electron distribution of Co sites. The electrochemical measurements show that the overpotential of LiCoO 2-x Cl x at 10 mA cm−2 for OER is reduced by 130 mV compared to LiCoO 2 by solid phase synthesized. Additionally, the lattice doping of Cl- can make the current density increase from 7.55 to 26.88 A g−1 at 2.0 V in Anion-exchange membrane water electrolyzer (AEMWE). The dual regulation strategy based on lattice doping of halogen ions provides a new viewpoint by adjusting coordination environment and optimizing reaction path for OER. [ABSTRACT FROM AUTHOR]

Designing a strategy to make the intrinsic activity of NiMo-based catalysts while being able to achieve long-term stable hydrogen production at ampere-level current densities is important for their development in AEM electrolyzers. Herein, interstitial boron atom-doped Ni 4 Mo is designed to obtain the catalyst with excellent alkaline HER properties. B 4.7 -Ni 4 Mo/NF exhibits a small overpotential of 135.2 mV at 1000 mA cm−2 and a high turnover frequency (TOF) value of 6.14 s−1 at 100 mV in alkaline HER, which very close to that of Pt/C (6.86 s−1). The catalyst requires only 1.73 V to achieve a current density of 1.0 A cm−2 in AEM electrolyzer at 60 °C and is stable for 800 h. Experimental and theoretical calculations reveal that interstitial boron doping not only optimizes the electronic structure to optimize H* adsorption and promote the water dissociation but also inhibits the dissolution of Mo by forming boron-metal bond. [Display omitted] • Interstitial-boron doping improves the Ni4Mo/NF activity by optimizing the adsorption of different intermediates. • The formation of boron-metal bond weakens the oxygenphilicity of Mo and inhibits the dissolution of Mo. • The AEM electrolyzer using this catalyst achieved long-term stability of 800 h at ampere-level current density. • DFT calculations reveal the role of boron atoms in promoting the catalytic activity and stability of Ni 4 Mo/NF. [ABSTRACT FROM AUTHOR]

A fuel cell is an electrochemical device that converts the chemical energy of a fuel and oxidant into electricity. Cation-exchange and anion-exchange membranes play an important role in hydrogen fed proton-exchange membrane (PEM) and anion-exchange membrane (AEM) fuel cells, respectively. Over the past 10 years, there has been growing interest in using nanofiber electrospinning to fabricate fuel cell PEMs and AEMs with improved properties, e.g., a high ion conductivity with low in-plane water swelling and good mechanical strength under wet and dry conditions. Electrospinning is used to create either reinforcing scaffolds that can be pore-filled with an ionomer or precursor mats of interwoven ionomer and reinforcing polymers, which after suitable processing (densification) form a functional membrane. In this review paper, methods of nanofiber composite PEMs and AEMs fabrication are reviewed and the properties of these membranes are discussed and contrasted with the properties of fuel cell membranes prepared using conventional methods. The information and discussions contained herein are intended to provide inspiration for the design of high-performance next-generation fuel cell ion-exchange membranes.

Electrolysis is seen as a promising route for the production of hydrogen from water, as part of a move to a wider “hydrogen economy”. The electro-oxidation of renewable feedstocks offers an alternative anode couple to the (high-overpotential) electrochemical oxygen evolution reaction for developing low-voltage electrolysers. Meanwhile, the exploration of new membrane materials is also important in order to try and reduce the capital costs of electrolysers. In this work, we synthesise and characterise a previously unreported anion-exchange membrane consisting of a fluorinated polymer backbone grafted with imidazole and trimethylammonium units as the ion-conducting moieties. We then investigate the use of this membrane in a lignin-oxidising electrolyser. The new membrane performs comparably to a commercially-available anion-exchange membrane (Fumapem) for this purpose over short timescales (delivering current densities of 4.4 mA cm−2 for lignin oxidation at a cell potential of 1.2 V at 70 °C during linear sweep voltammetry), but membrane durability was found to be a significant issue over extended testing durations. This work therefore suggests that membranes of the sort described herein might be usefully employed for lignin electrolysis applications if their robustness can be improved.

Mineral fouling of ion exchange membranes is one of the major problems during electrodialysis operation. The purpose of this work is the detection of the relationship between the structural and transport properties of the MA-40 anion exchange membrane after prolonged use desalinating and concentrating natural waters. Structural changes of the MA-40 anion exchange membrane after continuous operation in electrodialysis stacks of various types are evaluated by scanning electron microscopy. The physicochemical characteristics of membranes were identifi ed by the standard procedures. The conductivity was measured by the contact–difference method. The diffusion properties of the membranes were determined by estimating the amount of electrolyte, which was transported through the membrane to the water. The infl uence of structural changes in the MA-40 anion-exchange membrane after the electrodialysis of natural waters on the physical-chemical and electrochemical characteristics were estimated. The possible mechanisms of decreasing the operational characteristics of MA-40 membranes, which arise due to the demineralization and concentrating of natural waters, were revealed via the electrodialysis method. The main cause of reduction of the transport properties of membranes from near-electrode sections from the reverse electrodialysis stack during demineralization of natural waters from the Aral region is precipitation occurring both on the membrane surface and in its bulk. If on the membrane surface Mg insoluble compounds are preferably formed, then in the membrane phase on both sides of the surface the formation of CaCO3 is established. The main reason for the deterioration of the operational characteristics of the MA-40 anion-exchange membrane after electrodialysis concentration of natural waters is the destruction of ionogenic groups of the membranes, which causes a decrease in the total exchange capacity. The increase in surface macroporosity was accompanied by a slight mineral scaling of a carbonate nature.

N -Spirocyclic cations have excellent alkali resistance stability, and precise design of the structure of N -spirocyclic anion-exchange membranes (AEMs) improves their comprehensive performance. Here, we design and synthesize high-performance poly(triphenylene piperidine) membranes based on the "fishbone" design of amino/ N -spirocyclic cations. The "fishbone" design does not disrupt the overall stabilized conformation but promotes a microphase separation structure, while exerting the synergistic effect of piperidine cations and spirocyclic cations, resulting in a membrane with good conductivity and alkali resistance stability. The hydroxide conductivity of the QPTPip-ASU-X membrane reached up to 133.5 mS cm -1 at 80 °C. The QPTPip-ASU-15 membrane was immersed in a 2 M NaOH solution at 80 °C for 1200 h, and the conductivity was maintained at 91.02%. In addition, the QPTPip-ASU-5 membrane had the highest peak power density of 255 mW cm -2 .

This study presents the possibility of using diffusion dialysis for the separation of inorganic acids (hydrochloric, nitric, and hydrofluoric) and their ferric salts whose composition corresponds to that of real spent pickling solutions. At a steady state, the transport properties of three different anion-exchange membranes (Fumasep-FAD, Neosepta-AFN, and Neosepta-AHA) are compared using a continuous counter-current dialyzer. At a constant composition of the solutions (acid concentration 3 mol L -1 and iron concentration 30-40 g L -1 ), the effects of volumetric liquid flow rates on the transport rate of H + and Fe 3+ ions through the membrane are studied. The dialysis process is characterized by the recovery of acids and the rejection of salts. Furthermore, the values of the dialysis coefficients of acids, iron, and the acid/iron separation factors are calculated and compared. The volumetric flow rates of the inlet streams change in limits from 3 × 10 -8 to 6 × 10 -8 m 3 s -1 (from 3 to 6 L h -1 m -2 , relative to the membrane area). A comparison of the tested membranes shows slightly better results for acid recovery, iron rejection, and acid/iron separation factors for the Fumasep-FAD membrane than for the Neosepta-AFN membrane. However, the results obtained show that both of these anion-exchange membranes can be considered good separators for tested mixtures that simulate real spent pickling solutions, and there is a good precondition for using diffusion dialysis for processing these solutions in industrial practice. On the contrary, very low values of acid recovery and the overall dialysis coefficient of acid are found for the Neosepta-AHA membrane in the test range of the volumetric flow rate, and, thus, this membrane is insufficient for the adequate separation of these acids and iron salts.

Fuel cell-based anion-exchange membranes (AEMs) and proton exchange membranes (PEMs) are considered to have great potential as cost-effective, clean energy conversion devices. However, a fundamental atomistic understanding of the hydroxide and hydronium diffusion mechanisms in the AEM and PEM environment is an ongoing challenge. In this work, we aim to identify the fundamental atomistic steps governing hydroxide and hydronium transport phenomena. The motivation of this work lies in the fact that elucidating the key design differences between the hydroxide and hydronium diffusion mechanisms will play an important role in the discovery and determination of key design principles for the synthesis of new membrane materials with high ion conductivity for use in emerging fuel cell technologies. To this end, ab initio molecular dynamics simulations are presented to explore hydroxide and hydronium ion solvation complexes and diffusion mechanisms in the model AEM and PEM systems at low hydration in confined environments. We find that hydroxide diffusion in AEMs is mostly vehicular, while hydronium diffusion in model PEMs is structural. Furthermore, we find that the region between each pair of cations in AEMs creates a bottleneck for hydroxide diffusion, leading to a suppression of diffusivity, while the anions in PEMs become active participants in the hydronium diffusion, suggesting that the presence of the anions in model PEMs could potentially promote hydronium diffusion.

A polyketone-b-poly[N-(4 methyl-methylpyridium)-ethylenepyrrole+][X−], with X− = I− or OH−, is investigated as an example of anion-exchange membrane with potential applications in fuel cells. The polyketone starting material PK and the functionalized polyketones Pyr-FPKmI and Pyr-FPKmOH are investigated via Broadband Electrical Spectroscopy (BES) to understand the conductivity mechanism. BES signals are collected in the frequency range of 10−2 – 107 Hz and from −100° to 120 °C. BES measurements reveal the presence of up to three interdomain polarizations phenomena, one electrode polarization event and two β dielectric relaxation modes for both wet Pyr-FPKmI and Pyr-FPKmOH. Ion conductivity for Pyr-FPKmI and Pyr-FPKmOH is found to be 0.0086 and 0.0105 S cm−1 at 80 °C, respectively. The overall conductivity mechanism is attributed to the superposition of two conduction pathways, via delocalization bodies and via interdomain percolation pathways, which are associated with two different physical phenomena. [ABSTRACT FROM AUTHOR]

Moisture content in a strongly hydrophilic ion-exchange resin is one of the key parameters in commercial production of ion-exchange membranes. This work tried to clarify the effect of moisture content in an anion-exchange resin (AER) on the structure and final properties of anion-exchange membranes (AEMs). The AER was modified to 2, 4, 6, and 8% of moisture and then ground. The modified AER was blended with polyethylene and extruded to prepare AEMs, some of which were hot pressed. The microstructure and electrochemical properties of the AEMs were then determined. Variations in electrochemical properties showed no definite moisture effect except ion-exchange capacity, which decreased as AER moisture increased. The differences in changes in electrochemical properties were most apparent between pressed and non-pressed AEMs. Permselectivity and ionic resistance behaved similarly with AEM fixed ion concentration. The ionic resistance decreased with increasing fixed ion concentration. The same was true for permselectivity which is, however, in contradiction to Donnan theory. [ABSTRACT FROM AUTHOR]