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1
Grover, A. K., A. P. Singh, P. K. Rangachari et P. Nicholls. « Ion movements in membrane vesicles : a new fluorescence method and application to smooth muscle ». American Journal of Physiology-Cell Physiology 248, no 3 (1 mars 1985) : C372—C378. http://dx.doi.org/10.1152/ajpcell.1985.248.3.c372.
Texte intégralRésumé :
A method is described for studying ion permeabilities of membrane vesicles based on the principle that when membrane permeability to H+ is very high, the H+ movement is determined by the membrane potential generated by the H+ movement. The rate of H+ movement under these conditions thus gives a measure of the rate of dissipation of this membrane potential by comovement of anions or countermovement of cations present. Thus, by studying the H+ efflux using an impermeant cation and different anions, the membrane permeability to the anions can be assessed. Similarly, the use of an impermeant anion allows the study of the permeation of various cations. H+ movement was followed across the membranes by monitoring a change in the fluorescence intensity of the pH-sensitive dye pyranine trapped inside the membranes. This method when tested using phosphatidylcholine liposomes yielded the expected results, i.e., permeability of the liposomal membrane was: Cl- greater than SO2-4 and K+ greater than Na+. A plasma membrane-enriched fraction loaded with pyranine was isolated from estrogen-dominant rat myometrium. The anion permeability characteristics of this membrane were studied using tetramethylammonium (TMA+) as the poorly permeant cation, and the cation permeability was studied using L-glutamate- as the poorly permeant anion. The anion permeabilities were D-glutamate- less than L-glutamate- less than glutarate2- less than Cl- less than or equal to SO2-4, and the cation permeabilities were TMA+ less than K+ less than Na+. It is hypothesized that the observed anomalously higher Na+ and SO2-4 movements may involve special mechanisms.
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Kotyńska, Joanna, et Monika Naumowicz. « Theoretical Considerations and the Microelectrophoresis Experiment on the Influence of Selected Chaotropic Anions on Phosphatidylcholine Membrane Surface Charge Density ». Molecules 25, no 1 (29 décembre 2019) : 132. http://dx.doi.org/10.3390/molecules25010132.
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Influence of sodium salts of selected chaotropic anions from the Hofmeister series (NaCl, NaBr, NaNO3, NaI) on the surface charge density of phosphatidylcholine membranes was studied. Small unilamellar lipid vesicles were used as a model system in the investigations. The theoretical and experimental approach to the interactions between inorganic anions and phosphatidylcholine membranes is presented. Experimental membrane surface charge densities data were determined as a function of pH of the aqueous electrolytes using microelectrophoresis method. The quantitative description of the interactions between zwitterionic phosphatidylcholine membrane and monovalent anions is presented. The equilibria constants of the binding of solution ions onto phospholipid surface were calculated. Knowledge of these parameters was essential to determine the theoretical membrane surface charge density values. The theoretical data were compared to the experimental ones in order to verify the mathematical model. Both approaches indicate that the anion-phosphatidylcholine membrane interaction increases with the size of the anion. The adsorption of chaotropic anions to membranes was found to follow the Hofmeister series I− > NO3− > Br− > Cl−.
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Oliveira, Alexandra M., Brian P. Setzler et Yushan Yan. « Anode-Fed Anion Exchange Membrane Electrolyzers for Hydrogen Generation Tolerant to Anion Contaminants ». ECS Meeting Abstracts MA2022-02, no 44 (9 octobre 2022) : 1679. http://dx.doi.org/10.1149/ma2022-02441679mtgabs.
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Anion exchange membrane water electrolysis has the ability to produce green hydrogen with high voltage efficiencies at low capital cost with zero CO2 emissions. The alkaline environment of these devices allows for the use of economical metal catalysts and anion exchange membranes (AEMs) that conduct hydroxide ions and are less expensive than their proton exchange membrane counterparts. However, research has shown that anion contamination of hydroxide exchange membranes can lead to significant performance losses in anion exchange membrane fuel cells (AEMFCs), particularly when air fed to the oxygen-reducing cathode contains CO2.1 A similar contamination effect occurs in anion exchange membrane electrolyzers (AEMELs), when dissolved CO2 in the electrolyte reacts to form carbonate (CO3 2-) and bicarbonate (HCO3 2-) anions which compete with the hydroxide (OH-) ions that must be conducted through the AEM and ionomer. The presence of these and other anion contaminants can lower the ionic conductivity of the cell. Under high current density operation, an AEMEL undergoes a self-purging process that uses an ionic potential gradient to push hydroxide and anion contaminants through the membrane to the anode. This creates a significant pH gradient between cathode and anode that can lead to concentration polarization which further lowers performance.2 In this work, we use 1-D CO2 transport modeling and experiments to show how altering the electrolyte feed method allows for CO2-tolerant AEMEL operation in several different electrolytes. The unique advantages of AEMELs over AEMFCs and proton exchange membrane electrolyzers (PEMELs) are that (1) this self-purge occurs during normal operation, and (2) they allow for flexibility in the location of the potentially contaminated water feed. In PEMELs, water is intuitively fed to the anode, and cation contaminants are purged through the entire MEA to the cathode. Although water in AEMELs is intuitively fed to the cathode, where it is consumed in the hydrogen evolution reaction, water can diffuse easily through the membrane, allowing for it to be fed as an anolyte to the oxygen-evolving side of the cell. This allows for better contaminant rejection because anions can be concentrated mostly on the anode side of the electrolyzer. The model described in this paper predicts that an anode-fed AEMEL can more easily purge CO2 without contaminating as much of the AEM or inducing as high of a pH gradient due to more rapid self-purging of anions. We find experimentally that AEMELs with DI water anolyte are more tolerant of forced CO2 contamination than those with DI water catholytes, which is likely one of the major reasons for superior anode-feed performance. Furthermore, electrolyzer operation at high current densities can lead to voltage recoveries greater than 200 mV due to self-purging of anions. Although supporting electrolytes such as potassium hydroxide can mitigate catholyte contamination, the anion self-purging shows that electrolyzer operation in DI water and even tap water (containing fluoride, chloride, and nitrates) can improve when employing an anode feed. 1. Y. Zheng et al., Energy Environ. Sci., 12, 2806–2819 (2019). 2. B. P. Setzler, L. Shi, T. Wang, and Y. Yan, in ECS Meeting Abstracts, vol. MA2019-01, p. 1824–1824, IOP Publishing (2019) https://iopscience.iop.org/article/10.1149/MA2019-01/34/1824.
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Lejarazu-Larrañaga, Amaia, Juan Manuel Ortiz, Serena Molina, Yan Zhao et Eloy García-Calvo. « Nitrate-Selective Anion Exchange Membranes Prepared using Discarded Reverse Osmosis Membranes as Support ». Membranes 10, no 12 (27 novembre 2020) : 377. http://dx.doi.org/10.3390/membranes10120377.
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The present work shows a methodology for the preparation of membranes with a high affinity for nitrates. For this purpose, a polymeric mixture containing an anion exchange resin was extended on a recycled pressure filtration membrane used as mechanical support. Different ion exchange resins were tested. The influence in ion fractionation of (i) the type of ion exchange resin, (ii) the use of a recycled membrane as support and (iii) the operating current density during the separation process were studied. Results revealed that the employed anion exchange resin could tune up the transport numbers of the anions in the membrane and enhance the transport of nitrates over sulfates. The use of the recycled filtration membrane as support further increased the transport of nitrates in detriment of sulfates in nitrate-selective membranes. Moreover, it considerably improved the mechanical stability of the membranes. Lowering the operational current density also boosted ion fractionation. In addition, the use of recycled membranes as support in membrane preparation is presented as an alternative management route of discarded reverse osmosis membranes, coupling with the challenging management of waste generated by the desalination industry. These membranes could be used for nitrate recovery from wastewater or for nitrate separation from groundwater.
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Willdorf-Cohen, Sapir, Songlin Li, Simcha Srebnik, Charles E. Diesendruck et Dario R. Dekel. « Effect of Carbonate Anions on the Stability of Quaternary Ammonium Groups for Aemfcs ». ECS Meeting Abstracts MA2022-02, no 43 (9 octobre 2022) : 1609. http://dx.doi.org/10.1149/ma2022-02431609mtgabs.
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Anion-exchange membrane fuel cells (AEMFCs) have been attracting significant attention as a promising green and effective technology for energy conversion, suitable for both automotive and stationary applications. AEMFCs operate in an alkaline environment and thus allow the use of non-precious metal electrocatalysts from a wide selection of materials, as well as lower cost anion-exchange membranes (AEMs). In spite of the significant progress recently achieved, the commercial development of AEMFCs is hampered by both AEM degradation and the carbonation processes. The chemical decomposition of the AEMs during fuel cell operation is still considered as the main challenge that needs to be addressed. The combination of high pH environment and high current densities in the AEMFCs results in hydroxide anions with limited solvation, becoming extremely reactive towards positively charged quaternary ammonium (QA) salts. This decomposition leads to detrimental reduction in anion conductivity and therefore in fuel cell performance. Understanding the carbonation process is also critical to allow AEMFCs to operate with ambient air. Hydroxide anions created in the oxygen reduction reaction react with CO2 even at low concentrations, to form bi/carbonates ions. The lower diffusion coefficients and ionic mobility of CO3 -2 and HCO3 - increases resistivity and reduces power output. In this study we experimentally show for the first time the effect of carbonation on the degradation processes of the AEM. The experimental results are compared to modeling by MD. This study provides insights into the carbonation effect on cation stability in alkaline systems, which has significant implications for the final stability of AEMs resulting in long term operation of AEMFCs under real ambient air conditions. References: (1) Ziv, N.; Mustain, W. E.; Dekel, D. R. The Effect of Ambient Carbon Dioxide on Anion-Exchange Membrane Fuel Cells. ChemSusChem 2018, 11 (7), 1136–1150. https://doi.org/10.1002/cssc.201702330. (2) Yassin, K.; Rasin, I. G.; Willdorf-Cohen, S.; Diesendruck, C. E.; Brandon, S.; Dekel, D. R. A Surprising Relation between Operating Temperature and Stability of Anion Exchange Membrane Fuel Cells. J. Power Sources Adv. 2021, 11, 100066. https://doi.org/10.1016/j.powera.2021.100066. (3) Dekel, D. R.; Amar, M.; Willdorf, S.; Kosa, M.; Dhara, S.; Diesendruck, C. E. Effect of Water on the Stability of Quaternary Ammonium Groups for Anion Exchange Membrane Fuel Cell Applications. Chem. Mater. 2017, 29 (10), 4425–4431. https://doi.org/10.1021/acs.chemmater.7b00958. (4) Ziv, N.; Mondal, A. N.; Weissbach, T.; Holdcroft, S.; Dekel, D. R. Effect of CO2 on the Properties of Anion Exchange Membranes for Fuel Cell Applications. J. Memb. Sci. 2019, 586 (March), 140–150. https://doi.org/10.1016/j.memsci.2019.05.053. (5) Srebnik, S.; Pusara, S.; Dekel, D. R. Effect of Carbonate Anions on Quaternary Ammonium-Hydroxide Interaction. J. Phys. Chem. C 2019, 123 (26), 15956–15962. https://doi.org/10.1021/acs.jpcc.9b03131. (6) Vega, J. A.; Mustain, W. E. Effect of CO2, HCO3- and CO3-2 on Oxygen Reduction in Anion Exchange Membrane Fuel Cells. Electrochim. Acta 2010, 55 (5), 1638–1644. https://doi.org/10.1016/j.electacta.2009.10.041. (7) Zelovich, T.; Simari, C.; Nicotera, I.; Dekel, D. R.; Tuckerman, M. E. The Impact of Carbonation on Hydroxide Diffusion in Nano-Confined Anion Exchange Membranes. submitted to J. Materials Chem. A, Jan 29, 2022.
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Schefe, C. R., M. Watt, W. J. Slattery et P. M. Mele. « Organic anions in the rhizosphere of Al-tolerant and Al-sensitive wheat lines grown in an acid soil in controlled and field environments ». Soil Research 46, no 3 (2008) : 257. http://dx.doi.org/10.1071/sr07139.
Texte intégralRésumé :
Several sampling methods were investigated for the quantification of organic anions in the rhizosphere of Al-tolerant (ET8) and Al-sensitive (ES8) wheat plants in soil systems. Controlled environment studies used anion exchange membranes to collect rhizosphere organic anions (from root tips and mature regions of nodal roots) from ET8 and ES8 plants at the 6-leaf stage in a glasshouse environment. Using the anion exchange membranes, a selection of organic anions were detected on the tips and mature regions of roots, with ET8 and ES8 having similar rhizosphere organic anion profiles. The field experiment used 2 established methods of organic anion collection: rhizosphere soil and root washings. The ET8 and ES8 wheat lines had similar levels of organic anions, including malate, in the rhizosphere (using soil shaken from roots and root washings) at 3 sampling times (4 and 6 leaves, and flowering). The rhizosphere organic anions differed significantly from the bulk soil, with the concentration and range of organic anions in the rhizosphere decreasing towards flowering, presumably due to physiological changes in plant and root growth. This study used several techniques to investigate organic anion exudation by roots, with organic anions detected using all techniques. However, technical limitations of these techniques were recognised: (i) the lack of simultaneous exposure of root tips to both the anion exchange membrane and the chemical stimulant, e.g. Al3+; and (ii) the inability to derive the origin of organic anions measured in rhizosphere soil and root washings. The challenge for future soil-based organic anion research is to identify the dominant stress that has triggered an exudation response (i.e. Al toxicity, P deficiency), and to clearly differentiate between plant- and microbial-derived contributions to exudation.
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Miller, D. S., P. M. Smith et J. B. Pritchard. « Organic anion and cation transport in crab urinary bladder ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 257, no 3 (1 septembre 1989) : R501—R505. http://dx.doi.org/10.1152/ajpregu.1989.257.3.r501.
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Crab urinary bladder, a simple, flat-sheet epithelium, is structurally and functionally analogous to vertebrate renal proximal tubule. Like proximal tubule, crab bladder plays an important role in the excretion of potentially toxic, charged metabolites and xenobiotics. Bladders from Cancer borealis secrete monovalent, organic anions and cations in vivo and in vitro. For organic cations, secretion is a two-step process, with mediated and energetically downhill uptake into cells at the serosal membrane and uphill exit at the luminal membrane. The uptake step may be driven by the electrical potential difference across the serosal membrane, the luminal step by organic cation-proton exchange. Monovalent organic anions are also secreted by a separate two-step process. Recent experiments with intact bladder tissue and isolated membrane vesicles show that (as in mammalian proximal tubule) uphill serosal uptake can be coupled indirectly to the Na+ gradient. Organic anion (p-aminohippurate; PAH) uptake is driven by exchange for certain divalent organic anions, e.g., glutarate and alpha-ketoglutarate. The divalent anion gradient (in greater than out) is in turn maintained by Na+-coupled divalent uptake. The PAH exist step at the luminal membrane is mediated and downhill; it may involve anion exchange.
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Wei, Fei, Aslan Kosakian, Jiafei Liu et Marc Secanell. « Water Transport Characterization of Anion and Proton Exchange Membranes ». ECS Meeting Abstracts MA2022-02, no 50 (9 octobre 2022) : 2620. http://dx.doi.org/10.1149/ma2022-02502620mtgabs.
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Proton exchange membrane (PEM) and anion exchange membrane (AEM) fuel cells (FCs) are the two types of fuel cell devices that electrochemically convert the chemical energy of hydrogen into electricity and heat with water as the only by-product. Due to no requirement of precious and non-renewable platinum as the catalyst material, AEMFCs have attracted great attention in recent years [1,2]. However, water balance between anode and cathode in AEMFCs is more crucial than in PEMFCs, as water not only is produced in the anode, hindering hydrogen transport to the anode catalyst layer, but also functions as reactant in the cathode. Water transport properties of AEMs is one of the key factors affecting water balance between anode and cathode [1]. Accurate measurement of AEM water transport properties is paramount for AEM design and manufacturing to improve AEMFC water management and, in turn, performance and durability. AEMFCs with recently developed PiperION AEMs have been shown to achieve good AEMFC performance [3,4]; however, there is no available study in the literature measuring its water transport properties. To the best of the authors' knowledge, there are only a few studies reporting the measurement of AEMs water diffusivity, such as Fumapem FAA-3 [5,6], Aemion [5], Tokuyama A201 [7,8] and SnowPure Excellion I-200 [9]. Even in those limited studies, interfacial transport rates were either not considered in the data analysis [6,8,9] or not given as a function of water activity [5,7,8]. In this work, the interfacial desorption rate of AEMs is determined from a liquid-vapor permeation setup by measuring the water flux through the membrane at different relative humidity (RH). To quantify the interfacial exchange rate and determine which mode of transport is dominant (bulk or interfacial), a novel approach involving three different mathematical models was used: a diffusion-dominant model, a desorption-dominant model, and a combined diffusion-desorption model. By analyzing the sensitivity of the modeling results to the individual transport process, the dominant mode was identified. The model correctly identified the limiting transport mode in Nafion membranes, and suggested that interfacial transport was also limiting in AEMs of Aemion AH1-HNN8-50-X, Fumapem FAA-3-30/50 and PiperION-A40. With the developed model, semi-empirical relationships for the water desorption rate from AEMs and Nafion membranes as functions of the water content and temperature were obtained. These relationships can be readily used in AEMFCs and PEMFCs models. References [1] K. Yassin, et al., Quantifying the critical effect of water diffusivity in anion exchange membranes for fuel cell applications, Journal of Membrane Science 608 (2020) 118206. [2] X. Luo, et al., Structure-transport relationships of poly (aryl piperidinium) anion-exchange membranes: Eeffect of anions and hydration, Journal of Membrane Science 598 (2020) 117680. [3] J. Wang, et al., Poly (aryl piperidinium) membranes and ionomers for hydroxide exchange membrane fuel cells, Nature Energy 4(5) (2019) 392-398. [4] T. Wang, et al., High-performance hydroxide exchange membrane fuel cells through optimization of relative humidity, backpressure and catalyst selection, Journal of The Electrochemical Society 166(7) (2019) F3305. [5] X. Luo, et al., Water permeation through anion exchange membranes, Journal of Power Sources 375 (2018) 442-451. [6] M. Marino, et al., Hydroxide, halide and water transport in a model anion exchange membrane, Journal of Membrane Science 464 (2014) 61-71. [7] Y. Li, et al., Measurements of water uptake and transport properties in anion-exchange membranes, International Journal of Hydrogen Energy 35 (11) (2010) 5656-5665. [8] B. Eriksson, et al., Quantifying water transport in anion exchange membrane fuel cells, International Journal of Hydrogen Energy 44 (10) (2019) 4930–4939. [9] T.D. Myles, et al., Calculation of water diffusion coefficients in an anion exchange membrane using a water permeation technique, Journal of the Electrochemical Society 158(7) (2011) B790.
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Dong, X. W., J. B. Zhuang, N. B. Huang, C. H. Liang, L. S. Xu, W. Li, S. C. Zhang et M. Sun. « Development of anion-exchange membrane for anion-exchange membrane fuel cells ». Materials Research Innovations 19, sup6 (juin 2015) : S6–38—S6–41. http://dx.doi.org/10.1179/1432891715z.0000000001442.
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Zuo, Xingtao, Wenxin Shi, Shuili Yu et Jiajie He. « Fundamental characteristics study of anion-exchange PVDF–SiO2 membranes ». Water Science and Technology 66, no 11 (1 décembre 2012) : 2343–48. http://dx.doi.org/10.2166/wst.2012.464.
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A new type of poly(vinylidene fluoride)(PVDF)–SiO2 hybrid anion-exchange membrane was prepared by blending method. The anion-exchange groups were introduced by the reaction of epoxy groups with trimethylamine (TMA). Contact angle between water and the membrane surface was measured to characterize the hydrophilicity change of the membrane surface. The effects of nano-sized SiO2 particles in the membrane-forming materials on the membrane mechanical properties and conductivity were also investigated. The experimental results indicated that PVDF–SiO2 anion-exchange membranes exhibited better water content, ion-exchange capacity, conductivity and mechanic properties, and so may find potential applications in alkaline membrane fuel cells and water treatment processes.
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Smith, Stephen S., Erich D. Steinle, Mark E. Meyerhoff et David C. Dawson. « Cystic Fibrosis Transmembrane Conductance Regulator ». Journal of General Physiology 114, no 6 (29 novembre 1999) : 799–818. http://dx.doi.org/10.1085/jgp.114.6.799.
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The cystic fibrosis transmembrane conductance regulator (CFTR) Cl channel exhibits lyotropic anion selectivity. Anions that are more readily dehydrated than Cl exhibit permeability ratios (PS/PCl) greater than unity and also bind more tightly in the channel. We compared the selectivity of CFTR to that of a synthetic anion-selective membrane [poly(vinyl chloride)–tridodecylmethylammonium chloride; PVC-TDMAC] for which the nature of the physical process that governs the anion-selective response is more readily apparent. The permeability and binding selectivity patterns of CFTR differed only by a multiplicative constant from that of the PVC-TDMAC membrane; and a continuum electrostatic model suggested that both patterns could be understood in terms of the differences in the relative stabilization of anions by water and the polarizable interior of the channel or synthetic membrane. The calculated energies of anion–channel interaction, derived from measurements of either permeability or binding, varied as a linear function of inverse ionic radius (1/r), as expected from a Born-type model of ion charging in a medium characterized by an effective dielectric constant of 19. The model predicts that large anions, like SCN, although they experience weaker interactions (relative to Cl) with water and also with the channel, are more permeant than Cl because anion–water energy is a steeper function of 1/r than is the anion–channel energy. These large anions also bind more tightly for the same reason: the reduced energy of hydration allows the net transfer energy (the well depth) to be more negative. This simple selectivity mechanism that governs permeability and binding acts to optimize the function of CFTR as a Cl filter. Anions that are smaller (more difficult to dehydrate) than Cl are energetically retarded from entering the channel, while the larger (more readily dehydrated) anions are retarded in their passage by “sticking” within the channel.
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Karpenko, Tatyana, Nikita Kovalev, Vladislava Shramenko et Nikolay Sheldeshov. « Investigation of Transport Processes through Ion-Exchange Membranes Used in the Production of Amines from Their Salts Using Bipolar Electrodialysis ». Membranes 12, no 11 (10 novembre 2022) : 1126. http://dx.doi.org/10.3390/membranes12111126.
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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.
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Achoh, Aslan, Ilya Petriev et Stanislav Melnikov. « Removal of Excess Alkali from Sodium Naphthenate Solution by Electrodialysis Using Bilayer Membranes for Subsequent Conversion to Naphthenic Acids ». Membranes 11, no 12 (14 décembre 2021) : 980. http://dx.doi.org/10.3390/membranes11120980.
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The processing of solutions containing sodium salts of naphthenic acids (sodium naphthenate) is in high demand due to the high value of the latter. Such solutions usually include an excessive amount of alkali and a pH of around 13. Bipolar electrodialysis can convert sodium naphthenates into naphthenic acids; however, until pH 6.5, the naphthenic acids are not released from the solution. The primary process leading to a decrease in pH is the removal of excess alkali that implies that some part of electricity is wasted. In this work, we propose a technique for the surface modification of anion-exchange membranes with sulfonated polyetheretherketone, with the formation of bilayer membranes that are resistant to poisoning by the naphthenate anions. We investigated the electrochemical properties of the obtained membranes and their efficiency in a laboratory electrodialyzer. Modified membranes have better electrical conductivity, a high current efficiency for hydroxyl ions, and a low tendency to poisoning than the commercial membrane MA-41. We propose that the primary current carrier is the hydroxyl ion in both electromembrane systems with the MA-41 and MA-41M membranes. At the same time, for the modified MA-41M membrane, the concentration of hydroxyl ions in the anion-exchanger phase is higher than in the MA-41 membrane, which leads to almost five-fold higher values of the specific permeability coefficient. The MA-41M membranes are resistant to poisoning by naphthenic acids anions during at least six cycles of processing of the sodium naphthenate solution.
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Roelofsen, H., C. J. Soroka, D. Keppler et J. L. Boyer. « Cyclic AMP stimulates sorting of the canalicular organic anion transporter (Mrp2/cMoat) to the apical domain in hepatocyte couplets ». Journal of Cell Science 111, no 8 (15 avril 1998) : 1137–45. http://dx.doi.org/10.1242/jcs.111.8.1137.
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The canalicular membrane of rat hepatocytes contains an ATP-dependent multispecific organic anion transporter, also named multidrug resistance protein 2, that is responsible for the biliary secretion of several amphiphilic organic anions. This transport function is markedly diminished in mutant rats that lack the transport protein. To assess the role of vesicle traffic in the regulation of canalicular organic anion transport, we have examined the redistribution of the transporter to the canalicular membrane and the effect of cAMP on this process in isolated hepatocyte couplets, which retain secretory polarity. The partial disruption of cell-cell contact, due to the isolation procedure, leaves the couplet with both remnant apical membranes, as a source of apical proteins, and an intact apical domain and lumen, to which these proteins are targeted. The changes in distribution of the transporter were correlated to the apical excretion of a fluorescent substrate, glutathione-methylfluorescein. The data obtained in this study show that the transport protein, endocytosed from apical membrane remnants, first is redistributed along the basolateral plasma membrane. Then it is transcytosed to the remaining apical pole in a microtubule-dependent fashion, followed by the fusion of transporter-containing vesicles with the apical membrane. The cAMP analog dibutyrylcAMP stimulates all three steps, resulting in increased apically located transport protein, glutathione-methylfluorescein transport activity and apical membrane circumference. These findings indicate that the organic anion transport capacity of the apical membrane in hepatocyte couplets is regulated by cAMP-stimulated sorting of the multidrug resistance protein 2 to the apical membrane. The relevance of this phenomenon for the intact liver is discussed.
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Lee, Minyoung, Dahye Jeong, Mahamuda Akter et Jin Soo Park. « Development of Pore-Filling Anion Exchange Membranes for Anion Exchange Membrane Water Electrolysis : Enhancement of Alkaline Stability ». ECS Meeting Abstracts MA2022-02, no 41 (9 octobre 2022) : 1502. http://dx.doi.org/10.1149/ma2022-02411502mtgabs.
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Water electrolysis is a process that uses electricity to decompose water into oxygen and hydrogen. There are several types of ion exchange membrane can be used, anion exchange membrane, proton exchange membrane and bipolar membrane for water electrolysis. Alkaline based water electrolysis has several advantages to use non-precious electrocatalysts. However, the development of low resistance and durable anion-exchange membranes is of importance. In this study, several anion-exchange membranes were developed to enhance alkaline stability. Pore-filling anion exchange composite membranes with different contents of cross-linkers were prepared by mixing an electrolyte having good anion conducting ability. The mixture of monomers into a porous polyethylene (PE) substrate were polymerized by UV curing. The pore-filling reinforced composite membranes have been investigated in terms of good chemical stability properties, in particular, the variation of conductivity and mechanical strength in 1 M KOH at 60 oC. Characterization in terms of ion exchange capacity, water uptake, swelling ratio, and mechanical strength were also investigated. Acknowledgments This research was supported in part by "Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ016253)" Rural Development Administration, Republic of Korea, by the New and Renewable Energy of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20213030040520) and by 2022 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.
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Son, Tae Yang, Tae-Hyun Kim et Sang Yong Nam. « Crosslinked Pore-Filling Anion Exchange Membrane Using the Cylindrical Centrifugal Force for Anion Exchange Membrane Fuel Cell System ». Polymers 12, no 11 (23 novembre 2020) : 2758. http://dx.doi.org/10.3390/polym12112758.
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In this study, novel crosslinked pore-filling membranes were fabricated by using a centrifugal force from the cylindrical centrifugal machine. For preparing these crosslinked pore-filling membranes, the poly(phenylene oxide) containing long side chains to improve the water management (hydrophilic), porous polyethylene support (hydrophobic) and crosslinker based on the diamine were used. The resulting membranes showed a uniform thickness, flexible and transparent because it is well filled. Among them, PF-XAc-PPO70_25 showed good mechanical properties (56.1 MPa of tensile strength and 781.0 MPa of Young’s modulus) and dimensional stability due to the support. In addition, it has a high hydroxide conductivity (87.1 mS/cm at 80 °C) and low area specific resistance (0.040 Ω·cm2), at the same time showing stable alkaline stability. These data outperformed the commercial FAA-3-50 membrane sold by Fumatech in Germany. Based on the optimized properties, membrane electrode assembly using XAc-PPO70_25 revealed excellent cell performance (maximum power density: 239 mW/cm2 at 0.49 V) than those of commercial FAA-3-50 Fumatech anion exchange membrane (maximum power density: 212 mW/cm2 at 0.54 V) under the operating condition of 60 °C and 100% RH as well. It was expected that PF-XAc-PPO70_25 could be an excellent candidate based on the results superior to those of commercial membranes in these essential characteristics of fuel cells.
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Samsudin, Asep Muhamad, Merit Bodner et Viktor Hacker. « A Brief Review of Poly(Vinyl Alcohol)-Based Anion Exchange Membranes for Alkaline Fuel Cells ». Polymers 14, no 17 (29 août 2022) : 3565. http://dx.doi.org/10.3390/polym14173565.
Texte intégralRésumé :
Anion exchange membrane fuel cells have unique advantages and are thus gaining increasing attention. Poly(vinyl alcohol) (PVA) is one of the potential polymers for the development of anion exchange membranes. This review provides recent studies on PVA-based membranes as alternative anion exchange membranes for alkaline fuel cells. The development of anion exchange membranes in general, including the types, materials, and preparation of anion exchange membranes in the last years, are discussed. The performances and characteristics of recently reported PVA-based membranes are highlighted, including hydroxide conductivity, water uptake, swelling degree, tensile strength, and fuel permeabilities. Finally, some challenging issues and perspectives for the future study of anion exchange membranes are discussed.
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Karakoç, Ezgi, et Enver Güler. « Comparison of Physicochemical Properties of Two Types of Polyepichlorohydrin-Based Anion Exchange Membranes for Reverse Electrodialysis ». Membranes 12, no 3 (24 février 2022) : 257. http://dx.doi.org/10.3390/membranes12030257.
Texte intégralRésumé :
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.
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Ding, Jincheng, Shanshan Yang, Jiefeng Pan, Yu Zheng, Arcadio Sotto et Jiangnan Shen. « A novel nanofiltration membrane inspired by an asymmetric porous membrane for selective fractionation of monovalent anions in electrodialysis ». RSC Advances 8, no 53 (2018) : 30502–11. http://dx.doi.org/10.1039/c8ra05152f.
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Tosolini, Massimo, Paolo Pengo et Paolo Tecilla. « Biological Activity of Trans-Membrane Anion Carriers ». Current Medicinal Chemistry 25, no 30 (27 septembre 2018) : 3560–76. http://dx.doi.org/10.2174/0929867325666180309113222.
Texte intégralRésumé :
Natural and synthetic anionophores promote the trans-membrane transport of anions such as chloride and bicarbonate. This process may alter cellular homeostasis with possible effects on internal ions concentration and pH levels triggering several and diverse biological effects. In this article, an overview of the recent results on the study of aniontransporters, mainly acting with a carrier-type mechanism, is given with emphasis on the structure/activity relationship and on their biological activity as antibiotic and anticancer agents and in the development of new drugs for treating conditions derived from dysregulation of natural anion channels.
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Roch-Ramel, F., D. Werner et B. Guisan. « Urate transport in brush-border membrane of human kidney ». American Journal of Physiology-Renal Physiology 266, no 5 (1 mai 1994) : F797—F805. http://dx.doi.org/10.1152/ajprenal.1994.266.5.f797.
Texte intégralRésumé :
Mechanisms of urate transport were investigated in human renal brush-border membrane vesicles. The imposition of an outwardly directed Cl- gradient, in voltage-clamp and pH-clamp conditions, stimulated [14C]urate uptake. Organic anions, including pyrazinoate (PZA), probenecid, lactate, ketone bodies, succinate, and alpha-ketoglutarate in their monovalent forms, cis-inhibited [14C]urate uptake. The affinity order was PZA> urate > probenecid > other anions. Vesicle preloading with these anions trans-stimulated urate uptake. These observations demonstrate the presence of a urate/anion exchanger. p-Aminohippurate and OH- were not substrates for this exchanger. In the presence of an inwardly directed K+ gradient and valinomycin (intravesicular positive potential) [14C]urate uptake was stimulated. Voltage-sensitive [14C]urate uptake was cis-inhibited by organic anions in the following affinity order: urate > probenecid > PZA. The differences in affinity orders for the urate exchanger and the urate voltage-sensitive transport suggest different pathways for apical transport. The anion exchanger might be the main mechanism involved in urate tubular reabsorption in humans.
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Pritchard, J. B., et D. S. Miller. « Comparative insights into the mechanisms of renal organic anion and cation secretion ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 261, no 6 (1 décembre 1991) : R1329—R1340. http://dx.doi.org/10.1152/ajpregu.1991.261.6.r1329.
Texte intégralRésumé :
Comparative models have played a major role in defining the mechanisms that enable vertebrate proximal tubules to transport organic anions and cations from the peritubular interstitium to the urine. The unique advantages of these models and their contributions to our understanding of organic anion and cation transport mechanisms are summarized here. Recent studies of the organic anion transport system suggest that transport is coupled to metabolic energy via indirect coupling to the sodium gradient. Organic anions enter the cell across the basolateral membrane in exchange for alpha-ketoglutarate (alpha-KG), and the alpha-KG is returned to the interior via Na-alpha-KG cotransport. Indirect coupling to Na has been demonstrated in both isolated membranes and intact renal epithelial cells of species ranging from marine crustaceans to mammals. This mechanism was shown to drive not only cellular accumulation but also secretory transepithelial fluxes of organic anions. Luminal exit of secreted organic anions appears to be carrier mediated but is, at present, poorly understood, with mediated potential-driven efflux and anion exchange-driven efflux implicated in some species. As for organic anions, the renal clearance of some organic cations approaches the renal plasma flow. Although there is considerable variation in the handling of specific substrates between species, the basic properties of organic cation transport include carrier-mediated potential-driven uptake at the basolateral membrane, intracellular sequestration that reduces the free concentration of the cation, and luminal exit by organic cation-proton exchange. Reabsorptive transport is also observed for some organic cations, but its mechanisms and driving forces are not well understood.
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Jeong, Dahye, Minyoung Lee, Mahamuda Akter et Jin Soo Park. « Development of Pore-Filling Anion Exchange Membranes for Anion Exchange Membrane Water Electrolysis : Enhancement of Resistance ». ECS Meeting Abstracts MA2022-02, no 41 (9 octobre 2022) : 1501. http://dx.doi.org/10.1149/ma2022-02411501mtgabs.
Texte intégralRésumé :
Water electrolysis is a process that uses electricity to decompose water into oxygen and hydrogen. There are several types of ion exchange membrane can be used, anion exchange membrane, proton exchange membrane and bipolar membrane for water electrolysis. Alkaline based water electrolysis has several advantages to use non-precious electrocatalysts. However, the development of low resistance and durable anion-exchange membranes is of importance. In this study, several anion-exchange membranes were developed to enhance areal resistance, in other words, to minimize areal resistance. Pore-filling anion exchange composite membranes with different contents of cross-linkers were prepared by mixing an electrolyte having good anion conducting ability. The mixture of monomers into a porous polyethylene (PE) substrate were polymerized by UV curing. The pore-filling reinforced composite membranes have been investigated in terms of good electrochemical properties, in particular, areal resistance. The conductivity and areal specific resistance were measured in both in-plane cell and through-plane cell at 80 ℃ and at room temperature, respectively. Characterization in terms of ion exchange capacity, water uptake, swelling ratio, and mechanical strength were also investigated. Acknowledgments This research was supported in part by "Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ016253)" Rural Development Administration, Republic of Korea, by the New and Renewable Energy of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20213030040520) and by 2022 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.
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Villafaña-López, Liliana, Daniel M. Reyes-Valadez, Oscar A. González-Vargas, Victor A. Suárez-Toriello et Jesús S. Jaime-Ferrer. « Custom-Made Ion Exchange Membranes at Laboratory Scale for Reverse Electrodialysis ». Membranes 9, no 11 (4 novembre 2019) : 145. http://dx.doi.org/10.3390/membranes9110145.
Texte intégralRésumé :
Salinity gradient power is a renewable, non-intermittent, and neutral carbon energy source. Reverse electrodialysis is one of the most efficient and mature techniques that can harvest this energy from natural estuaries produced by the mixture of seawater and river water. For this, the development of cheap and suitable ion-exchange membranes is crucial for a harvest profitability energy from salinity gradients. In this work, both anion-exchange membrane and cation-exchange membrane based on poly(epichlorohydrin) and polyvinyl chloride, respectively, were synthesized at a laboratory scale (255 c m 2) by way of a solvent evaporation technique. Anion-exchange membrane was surface modified with poly(ethylenimine) and glutaraldehyde, while cellulose acetate was used for the cation exchange membrane structural modification. Modified cation-exchange membrane showed an increase in surface hydrophilicity, ion transportation and permselectivity. Structural modification on the cation-exchange membrane was evidenced by scanning electron microscopy. For the modified anion exchange membrane, a decrease in swelling degree and an increase in both the ion exchange capacity and the fixed charge density suggests an improved performance over the unmodified membrane. Finally, the results obtained in both modified membranes suggest that an enhanced performance in blue energy generation can be expected from these membranes using the reverse electrodialysis technique.
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Salhany, James M. « Anion binding characteristics of the band 3 / 4,4'-dibenzamidostilbene-2,2'-disulfonate binary complex : Evidence for both steric and allosteric interactions ». Biochemistry and Cell Biology 77, no 6 (1 décembre 1999) : 543–49. http://dx.doi.org/10.1139/o99-061.
Texte intégralRésumé :
A novel kinetic approach was used to measure monovalent anion binding to better define the mechanistic basis for competition between stilbenedisulfonates and transportable anions on band 3. An anion-induced acceleration in the release of 4,4prime-dibenzamidostilbene-2,2prime-disulfonate (DBDS) from its complex with band 3 was measured using monovalent anions of various size and relative affinity for the transport site. The K1/2 values for anion binding were determined and correlated with transport site affinity constants obtained from the literature and the dehydrated radius of each anion. The results show that anions with ionic radii of 120-200 pm fall on a well-defined correlation line where the ranking of the K1/2 values matched the ranking of the transport site affinity constants (thiocyanate < nitrate equivalent to bromide < chloride < fluoride). The K1/2 values for the anions on this line were about 4-fold larger than expected for anion binding to inhibitor-free band 3. Such a lowered affinity can be explained in terms of allosteric site-site interactions, since the K1/2 values decreased with increasing anionic size. In contrast, iodide, with an ionic radius of about 212 pm, had a 10-fold lower affinity than predicted by the correlation line established by the smaller monovalent anions. These results indicate that smaller monovalent anions have unobstructed access to the transport site within the band 3 / DBDS binary complex, while iodide experiences significant steric hindrance when binding. The observation of steric hindrance in iodide binding to the band 3 / DBDS binary complex, but not in the binding of smaller monovalent anions, suggests that the stilbenedisulfonate binding site is located at the outer surface of an access channel leading to the transport site.Key words: band 3, anion transport, membrane protein structure, red cell membrane.
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Gerencser, G. A., M. A. Cattey et G. A. Ahearn. « Sulfate/oxalate exchange by lobster hepatopancreatic basolateral membrane vesicles ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 269, no 3 (1 septembre 1995) : R572—R577. http://dx.doi.org/10.1152/ajpregu.1995.269.3.r572.
Texte intégralRésumé :
Purified basolateral membrane vesicles (BLMV) were prepared from lobster hepatopancreas by osmotic disruption and discontinuous sucrose gradient centrifugation. Radiolabeled sulfate uptake was stimulated by 10 mM intravesicular oxalate compared with gluconate-loaded vesicles. Sulfate/oxalate exchange was not affected by transmembrane valinomycin-induced potassium diffusion potentials (inside negative or inside positive), suggesting electroneutral anion transport. Sulfate uptake was not stimulated by the similar carboxylic anions formate, succinate, oxaloacetate, or ketoglutarate. Sulfate influx occurred by at least one saturable Michaelis-Menten carrier system [apparent Km = 6.0 +/- 1.7 mM; maximum flux (Jmax) = 382.3 +/- 37.0 pmol.mg protein-1 x 7 s-1]. Sulfate/oxalate exchange was significantly reduced by the anion antiport inhibitors 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid but was not affected by bumetanide or furosemide. The possible physiological role of this exchange mechanism in anion/sulfate transport across the crustacean hepatopancreas is discussed.
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Fernández-Nieto, Andrea, Sagrario Muñoz et Vicenta María Barragán. « Alcohol Diffusion in Alkali-Metal-Doped Polymeric Membranes for Using in Alkaline Direct Alcohol Fuel Cells ». Membranes 12, no 7 (28 juin 2022) : 666. http://dx.doi.org/10.3390/membranes12070666.
Texte intégralRésumé :
The alcohol permeability of anion exchange membranes is a crucial property when they are used as a solid electrolyte in alkaline direct alcohol fuel cells and electrolyzers. The membrane is the core component to impede the fuel crossover and allows the ionic transport, and it strongly affects the fuel cell performance. The aim of this work is to compare different anion exchange membranes to be used as an electrolyte in alkaline direct alcohol fuels cells. The alcohol permeability of four commercial anion exchange membranes with different structure were analyzed in several hydro-organic media. The membranes were doped using different types of alkaline doping agents (LiOH, NaOH, and KOH) and different conditions to analyze the effect of the treatment on the membrane behavior. Methanol, ethanol, and 1-propanol were analyzed. The study was focused on the diffusive contribution to the alcohol crossover that affects the fuel cell performance. To this purpose, alcohol permeability was determined for various membrane systems. The results show that membrane alcohol permeability is affected by the doping conditions, depending on the effect on the type of membrane and alcohol nature. In general, heterogeneous membranes presented a positive correlation between alcohol permeability and doping capacity, with a lower effect for larger-size alcohols. A definite trend was not observed for homogeneous membranes.
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Heo, Pilwon, Mijeong Kim, Hansol Ko, Sang Yong Nam et Kihyun Kim. « Self-Humidifying Membrane for High-Performance Fuel Cells Operating at Harsh Conditions : Heterojunction of Proton and Anion Exchange Membranes Composed of Acceptor-Doped SnP2O7 Composites ». Membranes 11, no 10 (11 octobre 2021) : 776. http://dx.doi.org/10.3390/membranes11100776.
Texte intégralRésumé :
Here we suggest a simple and novel method for the preparation of a high-performance self-humidifying fuel cell membrane operating at high temperature (>100 °C) and low humidity conditions (<30% RH). A self-humidifying membrane was effectively prepared by laminating together proton and anion exchange membranes composed of acceptor-doped SnP2O7 composites, Sn0.9In0.1H0.1P2O7/Sn0.92Sb0.08(OH)0.08P2O7. At the operating temperature of 100 °C, the electrochemical performances of the membrane electrode assembly (MEA) with this heterojunction membrane at 3.5% RH were better than or comparable to those of each MEA with only the proton or anion exchange membranes at 50% RH or higher.
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Vijayakumar, Vijayalekshmi, et Sang Yong Nam. « A Review of Recent Chitosan Anion Exchange Membranes for Polymer Electrolyte Membrane Fuel Cells ». Membranes 12, no 12 (14 décembre 2022) : 1265. http://dx.doi.org/10.3390/membranes12121265.
Texte intégralRésumé :
Considering the critical energy challenges and the generation of zero-emission anion exchange membrane (AEM) sources, chitosan-based anion exchange membranes have garnered considerable interest in fuel cell applications owing to their various advantages, including their eco-friendly nature, flexibility for structural modification, and improved mechanical, thermal, and chemical stability. The present mini-review highlights the advancements of chitosan-based biodegradable anion exchange membranes for fuel cell applications published between 2015 and 2022. Key points from the rigorous literature evaluation are: grafting with various counterions in addition to crosslinking contributed good conductivity and chemical as well as mechanical stability to the membranes; use of the interpenetrating network as well as layered structures, blending, and modified nanomaterials facilitated a significant reduction in membrane swelling and long-term alkaline stability. The study gives insightful guidance to the industry about replacing Nafion with a low-cost, environmentally friendly membrane source. It is suggested that more attention be given to exploring chitosan-based anion exchange membranes in consideration of effective strategies that focus on durability, as well as optimization of the operational conditions of fuel cells for large-scale applications.
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Alam, Md Mofasserul, Yaoming Wang, Chenxiao Jiang, Tingting Xu, Yahua Liu et Tongwen Xu. « A Novel Anion Exchange Membrane for Bisulfite Anion Separation by Grafting a Quaternized Moiety through BPPO via Thermal-Induced Phase Separation ». International Journal of Molecular Sciences 21, no 16 (12 août 2020) : 5782. http://dx.doi.org/10.3390/ijms21165782.
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Ion-exchange membranes are the core elements for an electrodialysis (ED) separation process. Phase inversion is an effective method, particularly for commercial membrane production. It introduces two different mechanisms, i.e., thermal induced phase separation (TIPS) and diffusion induced phase separation (DIPS). In this study, anion exchange membranes (AEMs) were prepared by grafting a quaternized moiety (QM,2-[dimethylaminomethyl]naphthalen-1-ol) through brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO) via the TIPS method. Those membranes were applied for selective bisulfite (HSO3−) anion separation using ED. The membrane surface morphology was characterized by SEM, and the compositions were magnified using a high-resolution transmission electron microscope (HRTEM). Notably, the membranes showed excellent substance stability in an alkali medium and in grafting tests performed in a QM-soluble solvent. The ED experiment indicated that the as-prepared membrane exhibited better HSO3− separation performance than the state-of-the-art commercial Neosepta AMX (ASTOM, Japan) membrane.
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Zhao, Di, Jinyun Xu, Yu Sun, Minjing Li, Guoqiang Zhong, Xudong Hu, Jiefang Sun et al. « Composition and Structure Progress of the Catalytic Interface Layer for Bipolar Membrane ». Nanomaterials 12, no 16 (21 août 2022) : 2874. http://dx.doi.org/10.3390/nano12162874.
Texte intégralRésumé :
Bipolar membranes, a new type of composite ion exchange membrane, contain an anion exchange layer, a cation exchange layer and an interface layer. The interface layer or junction is the connection between the anion and cation exchange layers. Water is dissociated into protons and hydroxide ions at the junction, which provides solutions to many challenges in the chemical, environmental and energy fields. By combining bipolar membranes with electrodialysis technology, acids and bases could be produced with low cost and high efficiency. The interface layer or junction of bipolar membranes (BPMs) is the connection between the anion and cation exchange layers, which the membrane and interface layer modification are vital for improving the performance of BPMs. This paper reviews the effect of modification of a bipolar membrane interface layer on water dissociation efficiency and voltage across the membrane, which divides into three aspects: organic materials, inorganic materials and newly designed materials with multiple components. The structure of the interface layer is also introduced on the performance of bipolar membranes. In addition, the remainder of this review discusses the challenges and opportunities for the development of more efficient, sustainable and practical bipolar membranes.
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Marin, B. P., et X. Gidrol. « Chloride-ion stimulation of the tonoplast H+-translocating ATPase from Hevea brasiliensis (rubber tree) latex. A dual mechanism ». Biochemical Journal 226, no 1 (15 février 1985) : 85–94. http://dx.doi.org/10.1042/bj2260085.
Texte intégralRésumé :
The effect of Cl- and other anions on the tonoplast H+-translocating ATPase (H+-ATPase) from Hevea brasiliensis (rubber tree) latex was investigated. Cl- and other anions stimulated the ATPase activity of tightly sealed vesicles prepared from Hevea tonoplast, with the following decreasing order of effectiveness: Cl- greater than Br- greater than SO4(2-) greater than NO3-. As indicated by the changes of the protonmotive potential difference, anion stimulation of tonoplast H+-ATPase was caused in part by the ability of these anions to dissipate the electrical potential. This interpretation assumes not a channelling of these anions against a membrane potential, negative-inside, but a modification of the permeability of these ions through the tonoplast membrane. In addition, Cl- and the other anions stimulated the ATPase activity solubilized from the tonoplast membrane. Consequently, the tonoplast H+-pumping ATPase can be considered as an anion-stimulated enzyme. These results are discussed in relation to various models described in the literature for the microsomal H+-ATPase systems claimed as tonoplast entities.
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Williams, A. J. K., et R. E. Barry. « Superoxide anion production and degranulation of rat neutrophils in response to acetaldehyde-altered liver cell membranes ». Clinical Science 71, no 3 (1 septembre 1986) : 313–18. http://dx.doi.org/10.1042/cs0710313.
Texte intégralRésumé :
1. Rat liver membrane vesicles were exposed to acetaldehyde, with or without reduction of the resultant adducts formed. 2. Superoxide anion production and degranulation of rat neutrophils, upon stimulation with the liver membrane vesicles, were measured by cytochrome c reduction before and after the addition of superoxide dismutase, and β-glucuronidase release respectively. 3. Preincubation with acetaldehyde significantly enhanced superoxide anion production by both the reduced and non-reduced membrane samples (1.7-fold and 4.4-fold, respectively). 4. Preincubation with acetaldehyde significantly enhanced degranulation (1.5-fold) of neutrophils in response to the non-reduced membranes only. The reductive process itself caused a marked increase (2.4-fold) in the ability of the membrane vesicles to stimulate degranulation. 5. Cytochalasin B, an inhibitor of phagocytosis, did not reduce degranulation, implying that it occurred as a consequence of cell surface stimulation. 6. Neutrophil superoxide anion production and lysosomal enzyme release in response to acetaldehyde-altered liver cell membranes could be an important mechanism of hepatocyte injury in alcoholic liver disease.
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Zhang, Shou Hai, Ben Gui Zhang et Xi Gao Jian. « Preparation and Properties of Poly (phthalazinone Ether Ketone) Based Anion Exchange Membranes for Vanadium Redox Flow Battery ». Advanced Materials Research 773 (septembre 2013) : 171–74. http://dx.doi.org/10.4028/www.scientific.net/amr.773.171.
Texte intégralRésumé :
Poly (phthalazinone ether ketone) anion exchange membranes with pyridinium groups (PyPPEK) for vanadium redox flow battery were prepared from chloromethylated poly (phthalazinone ether ketone) and pyridine. The chemical structure of PyPPEK was characterized by using FT-IR spectrum. Compared with quaternary ammonium group containing poly (phthalazinone ether ketone), PyPPEK membrane showed low ion exchange capacity, low swelling ratio and comparable tensile strength. Columbic efficiencies of VRB with anion exchange membranes were higher than that of VRB with Nafion117 membrane. When the ion exchange capacity of PyPPEK membrane was 1.40 mmol·g-1, energy efficiency of VRB with the membrane was higher than that of VRB with Nafion117 membrane at charge-discharge current densities ranging from 20 mA·cm-2 to 50 mA·cm-2.
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Brown, C. D., C. R. Dunk et L. A. Turnberg. « Cl-HCO3 exchange and anion conductance in rat duodenal apical membrane vesicles ». American Journal of Physiology-Gastrointestinal and Liver Physiology 257, no 4 (1 octobre 1989) : G661—G667. http://dx.doi.org/10.1152/ajpgi.1989.257.4.g661.
Texte intégralRésumé :
Transport mechanisms for Cl and HCO3 anions in the apical membrane of rat duodenal enterocytes have been characterized using brush-border membrane vesicles. 36Cl uptake was stimulated by outwardly directed gradients of OH, HCO3, and Cl anions. The anion exchanger was sensitive to inhibition by 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) (Ki, 1.3 mmol/l), 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), and furosemide. The process was electroneutral, since voltage clamping the membrane potential to 0 mV or applying a large inside-positive potential had no effect on the magnitude of uptake. The kinetic properties of the exchanger were measured and an apparent Km of 9.8 mM Cl and a Vmax of 134 nmol.mg protein-1.4 s-1 were found. In addition, an electrogenic conductive component of 36Cl uptake was found. This component was dependent on an inside-positive membrane potential and was inhibited by the Cl channel blocker diphenylamine-2-carboxylate. SITS, DIDS, and furosemide had no effect on the electrogenic component of 36Cl uptake. An apparent anion selectivity of SCN greater than I greater than Br greater than Cl greater than HCO3 greater than SO4 greater than Glu greater than PO4 was found. These results support the presence of both Cl-HCO3 exchange and a conductive anion channel in the apical membrane of rat duodenal enterocytes.
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Inaba, Mutsumi. « Molecular Pathology of Anion Exchanger 1 (AE1) ». membrane 35, no 6 (2010) : 262–67. http://dx.doi.org/10.5360/membrane.35.262.
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Zarybnicka, Lucie, Eliska Stranska, Jana Machotova et Gabriela Lencova. « Preparation of Two-Layer Anion-Exchange Poly(ethersulfone) Based Membrane : Effect of Surface Modification ». International Journal of Polymer Science 2016 (2016) : 1–8. http://dx.doi.org/10.1155/2016/8213694.
Texte intégralRésumé :
The present work deals with the surface modification of a commercial microfiltration poly(ethersulfone) membrane by graft polymerization technique. Poly(styrene-co-divinylbenzene-co-4-vinylbenzylchloride) surface layer was covalently attached onto the poly(ethersulfone) support layer to improve the membrane electrochemical properties. Followed by amination, a two-layer anion-exchange membrane was prepared. The effect of surface layer treatment using the extraction in various solvents on membrane morphological and electrochemical characteristics was studied. The membranes were tested from the point of view of water content, ion-exchange capacity, specific resistance, permselectivity, FT-IR spectroscopy, and SEM analysis. It was found that the two-layer anion-exchange membranes after the extraction using tetrahydrofuran or toluene exhibited smooth and porous surface layer, which resulted in improved ion-exchange capacity, electrical resistance, and permselectivity of the membranes.
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Yang, Jin, Qian Chen, Noor Ul Afsar, Liang Ge et Tongwen Xu. « Poly(alkyl-biphenyl pyridinium)-Based Anion Exchange Membranes with Alkyl Side Chains Enable High Anion Permselectivity and Monovalent Ion Flux ». Membranes 13, no 2 (3 février 2023) : 188. http://dx.doi.org/10.3390/membranes13020188.
Texte intégralRésumé :
Poly(alkyl-biphenyl pyridinium)-based anion exchange membranes with alkyl side chains were synthesized for permselective anion separation. By altering the length of the grafted side chain, the hydrophilicity and other attributes of the membranes could be controlled. The QDPAB-C5 membrane with the best comprehensive performance exhibited a Cl− ion flux of 3.72 mol m−2 h−1 and a Cl−/SO42− permselectivity of 15, which are significantly better than the commercial Neosepta ACS membrane. The QDPAB-C5 membranes with distinct microscopic phase separation structures formed interconnected hydrophilic/hydrophobic ion channels and exhibited excellent ion flux and permselectivity for other anionic systems (NO3−/SO42−, Br−/SO42−, F−/SO42−, NO3−/Cl−, Br−/Cl−, and F−/Cl−) as well. Furthermore, the influence of alkyl side chain length on the membranes’ ion flux and permselectivity in electrodialysis was investigated, which may be attributed to the alterations in ion channels and hydrophobic regions of the membranes. This work provides an effective strategy for the development of monovalent anion permselective membranes.
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Zhao, Yan, Congjie Gao et Bart Van der Bruggen. « Technology-driven layer-by-layer assembly of a membrane for selective separation of monovalent anions and antifouling ». Nanoscale 11, no 5 (2019) : 2264–74. http://dx.doi.org/10.1039/c8nr09086f.
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Shirataki, Hironobu. « Protein Purification Using Anion–Exchange Hollow–Fiber Membrane ». MEMBRANE 39, no 4 (2014) : 264–67. http://dx.doi.org/10.5360/membrane.39.264.
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Jawad, Noor H., Ali Amer Yahya, Ali R. Al-Shathr, Hussein G. Salih, Khalid T. Rashid, Saad Al-Saadi, Adnan A. AbdulRazak, Issam K. Salih, Adel Zrelli et Qusay F. Alsalhy. « Fuel Cell Types, Properties of Membrane, and Operating Conditions : A Review ». Sustainability 14, no 21 (7 novembre 2022) : 14653. http://dx.doi.org/10.3390/su142114653.
Texte intégralRésumé :
Fuel cells have lately received growing attention since they allow the use of non-precious metals as catalysts, which reduce the cost per kilowatt of power in fuel cell devices to some extent. Until recent years, the major barrier in the development of fuel cells was the obtainability of highly conductive anion exchange membranes (AEMs). On the other hand, improvements show that newly enhanced anion exchange membranes have already reached high conductivity levels, leading to the suitable presentation of the cell. Currently, an increasing number of studies have described the performance results of fuel cells. Much of the literature reporting cell performance is founded on hydrogen‒anion exchange membrane fuel cells (AEMFCs), though a growing number of studies have also reported utilizing fuels other than hydrogen—such as alcohols, non-alcohol C-based fuels, and N-based fuels. This article reviews the types, performance, utilized membranes, and operational conditions of anion exchange membranes for fuel cells.
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Premakshi, H. G., M. Y. Kariduraganavar et G. R. Mitchell. « Development of composite anion-exchange membranes using poly(vinyl alcohol) and silica precursor for pervaporation separation of water–isopropanol mixtures ». RSC Advances 6, no 14 (2016) : 11802–14. http://dx.doi.org/10.1039/c5ra19858e.
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Composite anion-exchange membranes (AEMs) were prepared using sol–gel techniques with poly(vinyl alcohol) and anion-exchange silica precursor (AESP). Among the composite AEMs, the membrane containing 4 mass% of AESP (M-4) exhibited the excellent pervaporation performance.
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Cho, Hyeongrae, Henning Krieg et Jochen Kerres. « Performances of Anion-Exchange Blend Membranes on Vanadium Redox Flow Batteries ». Membranes 9, no 2 (17 février 2019) : 31. http://dx.doi.org/10.3390/membranes9020031.
Texte intégralRésumé :
Anion exchange blend membranes (AEBMs) were prepared for use in Vanadium Redox Flow Batteries (VRFBs). These AEBMs consisted of 3 polymer components. Firstly, PBI-OO (nonfluorinated PBI) or F6-PBI (partially fluorinated PBI) were used as a matrix polymer. The second polymer, a bromomethylated PPO, was quaternized with 1,2,4,5-tetramethylimidazole (TMIm) which provided the anion exchange sites. Thirdly, a partially fluorinated polyether or a non-fluorinated poly (ether sulfone) was used as an ionical cross-linker. While the AEBMs were prepared with different combinations of the blend polymers, the same weight ratios of the three components were used. The AEBMs showed similar membrane properties such as ion exchange capacity, dimensional stability and thermal stability. For the VRFB application, comparable or better energy efficiencies were obtained when using the AEBMs compared to the commercial membranes included in this study, that is, Nafion (cation exchange membrane) and FAP 450 (anion exchange membrane). One of the blend membranes showed no capacity decay during a charge-discharge cycles test for 550 cycles run at 40 mA/cm2 indicating superior performance compared to the commercial membranes tested.
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Li, Man-Song, Ryan G. Holstead, Wuyang Wang et Paul Linsdell. « Regulation of CFTR chloride channel macroscopic conductance by extracellular bicarbonate ». American Journal of Physiology-Cell Physiology 300, no 1 (janvier 2011) : C65—C74. http://dx.doi.org/10.1152/ajpcell.00290.2010.
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The CFTR contributes to Cl− and HCO3− transport across epithelial cell apical membranes. The extracellular face of CFTR is exposed to varying concentrations of Cl− and HCO3− in epithelial tissues, and there is evidence that CFTR is sensitive to changes in extracellular anion concentrations. Here we present functional evidence that extracellular Cl− and HCO3− regulate anion conduction in open CFTR channels. Using cell-attached and inside-out patch-clamp recordings from constitutively active mutant E1371Q-CFTR channels, we show that voltage-dependent inhibition of CFTR currents in intact cells is significantly stronger when the extracellular solution contains HCO3− than when it contains Cl−. This difference appears to reflect differences in the ability of extracellular HCO3− and Cl− to interact with and repel intracellular blocking anions from the pore. Strong block by endogenous cytosolic anions leading to reduced CFTR channel currents in intact cells occurs at physiologically relevant HCO3− concentrations and membrane potentials and can result in up to ∼50% inhibition of current amplitude. We propose that channel block by cytosolic anions is a previously unrecognized, physiologically relevant mechanism of channel regulation that confers on CFTR channels sensitivity to different anions in the extracellular fluid. We further suggest that this anion sensitivity represents a feedback mechanism by which CFTR-dependent anion secretion could be regulated by the composition of the secretions themselves. Implications for the mechanism and regulation of CFTR-dependent secretion in epithelial tissues are discussed.
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Kuppusamy, Hari Gopi, Prabhakaran Dhanasekaran, Niluroutu Nagaraju, Maniprakundil Neeshma, Baskaran Mohan Dass, Vishal M. Dhavale, Sreekuttan M. Unni et Santoshkumar D. Bhat. « Anion Exchange Membranes for Alkaline Polymer Electrolyte Fuel Cells—A Concise Review ». Materials 15, no 16 (15 août 2022) : 5601. http://dx.doi.org/10.3390/ma15165601.
Texte intégralRésumé :
Solid anion exchange membrane (AEM) electrolytes are an essential commodity considering their importance as separators in alkaline polymer electrolyte fuel cells (APEFC). Mechanical and thermal stability are distinguished by polymer matrix characteristics, whereas anion exchange capacity, transport number, and conductivities are governed by the anionic group. The physico-chemical stability is regulated mostly by the polymer matrix and, to a lesser extent, the cationic head framework. The quaternary ammonium (QA), phosphonium, guanidinium, benzimidazolium, pyrrolidinium, and spirocyclic cation-based AEMs are widely studied in the literature. In addition, ion solvating blends, hybrids, and interpenetrating networks still hold prominence in terms of membrane stability. To realize and enhance the performance of an alkaline polymer electrolyte fuel cell (APEFC), it is also necessary to understand the transport processes for the hydroxyl (OH−) ion in anion exchange membranes. In the present review, the radiation grafting of the monomer and chemical modification to introduce cationic charges/moiety are emphasized. In follow-up, the recent advances in the synthesis of anion exchange membranes from poly(phenylene oxide) via chloromethylation and quaternization, and from aliphatic polymers such as poly(vinyl alcohol) and chitosan via direct quaternization are highlighted. Overall, this review concisely provides an in-depth analysis of recent advances in anion exchange membrane (AEM) and its viability in APEFC.
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Harig, J. M., K. H. Soergel, J. A. Barry et K. Ramaswamy. « Transport of propionate by human ileal brush-border membrane vesicles ». American Journal of Physiology-Gastrointestinal and Liver Physiology 260, no 5 (1 mai 1991) : G776—G782. http://dx.doi.org/10.1152/ajpgi.1991.260.5.g776.
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Human ileal brush-border membrane vesicles were employed to study the mechanisms of short-chain fatty acid (propionate) absorption especially to determine the effects of intravesicular HCO3- and the component of nonionic diffusion. Preloading the vesicles with HCO3- resulted in up to 20-fold "overshoots" of transport, and this effect was not seen with other intravesicular anions. This transport process was very fast (peak uptake 6 s) and was not due to intravesicular buffering by HCO3-. Radiolabeled propionate transport demonstrated transstimulation when the vesicles were preloaded with unlabeled propionate. An inward H+ gradient led to stimulation of propionate transport much smaller than in the presence of trans-HCO3-, whereas an inward Na+ gradient had no effect. Propionate transport was attenuated by the anion exchange inhibitors SITS and DIDS. Under HCO3- gradient conditions, propionate transport exhibited saturation kinetics with an apparent Km of 21 +/- 3 mM and a Vmax of 50 +/- 3 nmol.mg protein-1.3 s-1. Propionate transport was inhibited up to 40% by 2-5 carbon short-chain fatty acids (10 mM) but not by other organic anions. Short-chain fatty acid transport in the human ileum is Na+ independent and occurs mostly via a specific anion exchange mechanism with HCO3-. Our results also demonstrate a small component of nonionic diffusion of the protonated fatty acid (or anion exchange for OH-).
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Son, Tae Yang, Kwang Seop Im, Ha Neul Jung et Sang Yong Nam. « Blended Anion Exchange Membranes for Vanadium Redox Flow Batteries ». Polymers 13, no 16 (23 août 2021) : 2827. http://dx.doi.org/10.3390/polym13162827.
Texte intégralRésumé :
In this study, blended anion exchange membranes were prepared using polyphenylene oxide containing quaternary ammonium groups and polyvinylidene fluoride. A polyvinylidene fluoride with high hydrophobicity was blended in to lower the vanadium ion permeability, which increased when the hydrophilicity increased. At the same time, the dimensional stability also improved due to the excellent physical properties of polyvinylidene fluoride. Subsequently, permeation of the vanadium ions was prevented due to the positive charge of the anion exchange membrane, and thus the permeability was relatively lower than that of a commercial proton exchange membrane. Due to the above properties, the self-discharge of the blended anion exchange membrane (30.1 h for QA–PPO/PVDF(2/8)) was also lower than that of the commercial proton exchange membrane (27.9 h for Nafion), and it was confirmed that it was an applicable candidate for vanadium redox flow batteries.
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Zhang, Yiming, Wei Zhang et Luis F. Cházaro-Ruiz. « Porous PVDF/PANI ion-exchange membrane (IEM) modified by polyvinylpyrrolidone (PVP) and lithium chloride in the application of membrane capacitive deionisation (MCDI) ». Water Science and Technology 77, no 9 (5 avril 2018) : 2311–19. http://dx.doi.org/10.2166/wst.2018.152.
Texte intégralRésumé :
Abstract In this work, polyvinylidene fluoride (PVDF)/polyaniline (PANI) heterogeneous anion-exchange membranes filled with pore-forming agents polyvinylpyrrolidone (PVP) and lithium chloride were prepared by the solution-casting technique using the solvent 1-methyl-2-pyrrolidone (NMP) and a two-step phase inversion procedure. Key properties of the as-prepared membranes, such as hydrophilicity, water content, ion exchange capacity, fixed ion concentration, conductivity and transport number were examined and compared between membranes in different conditions. The pore-forming hydrophilic additives PVP and lithium chloride to the casting solution appeared to improve the ion-exchange membranes (IEMs) by increasing the conductivity, transport number and hydrophilicity. The effects of increasing membrane drying time on the porosity of the as-prepared membranes were found to lower membrane porosity by reducing membrane water content. However, pore-forming agents were found to be able to stabilise membrane transport number with different drying times. As-prepared PVDF/PANI anion-exchange membrane with pore-forming agent is demonstrated to be a more efficient candidate for water purification (e.g. desalination) and other industrial applications.
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ITO, Hiroshi. « Anion Exchange Membrane Water Electrolysis ». Denki Kagaku 89, no 3 (5 septembre 2021) : 247–51. http://dx.doi.org/10.5796/denkikagaku.21-fe0021.
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Berezin, Sofya Kostina, et Jeffery T. Davis. « Catechols as Membrane Anion Transporters ». Journal of the American Chemical Society 131, no 7 (25 février 2009) : 2458–59. http://dx.doi.org/10.1021/ja809733c.
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