Commercial Ion Exchange Membranes Research Articles

Preparation and characterization of polyvinyl alcohol polyelectrolyte-based membrane-anode assembly for hybrid Fe3+/H2 redox flow microbial fuel cell

The redox Fe3+/H2 flow fuel cell electrolytes are based on thin polymeric membranes that conduct protons (H+ ions). This paper reports the study of polyvinyl alcohol (PVA) based polyelectrolyte membranes (PEM) for application in redox flow fuel cells. The PVA polyelectrolyte membranes (PVA-PEMs) were supported on a gas diffusion electrode (GDE), and cross-linked in situ using glutaraldehyde (GA) in the presence of acidic catalyst, forming a membrane-anode assembly. Multiple coating layers of PVA/GA were applied on the GDE for obtaining different membrane thicknesses. The swelling study indicated that the water uptake of the membranes decreased linearly with the increase in the GA content due to the increase in the cross-link density. The GA content of 11 wt.% showed a maximum gel content of 98.4% and optimum water uptake of 40%. The overall ionic (iron ions and acid) crossover flux through PVA-PEMs was lower than that in the Nafion® 112 ionomer membrane. The two-layer of PVA-PEMs on Nafion postcoated GDE exhibited the maximum power density of 170 mW cm−2 at current density of 472 mA cm−2. In the case of the commercial Selemion HSF ion exchange membrane, the maximum power density was found to be 166 mW cm−2 at current density of 472 mA cm−2. The continuous operation of the redox flow cells with PVA-PEMs exhibited stability with 92% retention in cell voltage after 480 h.

Enhanced desalination efficiency in modified membrane capacitive deionization by introducing ion-exchange polymers in carbon nanotubes electrodes

A modified membrane capacitive deionization (m-MCDI) device was proposed with high desalination efficiency. The m-MCDI electrodes were fabricated by introducing the anion exchange polymer (dimethyl diallyl ammonium chloride) and cation exchange (polyethyleneimine) polymer into carbon nanotubes (CNTs) electrodes and their desalination performance in NaCl solutions was investigated. The m-MCDI unit cell based on both anion and cation exchange polymers exhibits a high NaCl removal of 93%, much higher than that of conventional capacitive deionization cell with CNTs electrode (25%) or MCDI cell with commercial anion and cation exchange membranes (74%) in a certain experiment at 1.2V and for an initial conductivity of 50μS/cm. The large improvement in desalination performance is mainly due to the reduced co-ion expulsion effect by introducing ion exchange polymers and the better contact adhesion between ion exchange polymers and electrodes than between commercial ion exchange membranes and electrodes.

The Effects of Sulfonated Poly(ether ether ketone) Ion Exchange Preparation Conditions on Membrane Properties.

A low cost cation exchange membrane to be used in a specific bioelectrochemical system has been developed using poly(ether ether ketone) (PEEK). This material is presented as an alternative to current commercial ion exchange membranes that have been primarily designed for fuel cell applications. To increase the hydrophilicity and ion transport of the PEEK material, charged groups are introduced through sulfonation. The effect of sulfonation and casting conditions on membrane performance has been systematically determined by producing a series of membranes synthesized over an array of reaction and casting conditions. Optimal reaction and casting conditions for producing SPEEK ion exchange membranes with appropriate performance characteristics have been established by this uniquely systematic experimental series. Membrane materials were characterized by ion exchange capacity, water uptake, swelling, potential difference and NMR analysis. Testing this extensive membranes series established that the most appropriate sulfonation conditions were 60 °C for 6 h. For mechanical stability and ease of handling, SPEEK membranes cast from solvent casting concentrations of 15%–25% with a resulting thickness of 30–50 µm were also found to be most suitable from the series of tested casting conditions. Drying conditions did not have any apparent impact on the measured parameters in this study. The conductivity of SPEEK membranes was found to be in the range of 10−3 S cm−1, which is suitable for use as a low cost membrane in the intended bioelectrochemical systems.

Synthesis and electrochemical behavior of ceramic cation-exchange membranes based on zirconium phosphate

Abstract Cation-exchange membranes made exclusively from ceramic materials have been synthesized by means of the impregnation of microporous ceramic supports with zirconium phosphate. Changes in the pore size distribution and total pore volume of the supports were provoked by the addition of starch as pore former in the fabrication procedure. This allowed the production of supports with increased effective electrical conductivities and with larger pores available for the zirconium phosphate deposition. An improved functionality for the exchange of cations was given to the ceramic membranes by means of their impregnation with the active particles of zirconium phosphate. The ion-exchange properties of the membranes were increased with further impregnation cycles and the resulting current–voltage curves showed a similar shape to that typical of commercial polymeric ion-exchange membranes. The production of ion-exchange membranes with increased chemical and radiation stability will broaden their applicability for the treatment of specific industrial waste waters, which are very aggressive for the current commercial ion-exchange membranes.

Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

Effect of the ion-exchange-membrane/solution interfacial characteristics on the mass transfer at severe current regimes

In the electrodialysis of dilute solutions, performed at intense current regimes, the membrane electrical conductance and diffusion permeability are no more crucial. Of more importance become the membrane properties that control increase in the overlimiting mass transfer of salt ions, as well as H+ and OH− ions in membrane systems. In this work different methods of the improving of mass-exchange characteristics of commercial ion-exchange membranes intended for operation at intense current regimes are discussed. They are based on modern concepts of mechanisms of the electroconvection (which proceeds as electroosmosis of 2nd kind), as well as mechanisms of H+ and OH− ions generation at the membrane/solution interface. Influence on the membrane electrochemical and mass-exchange characteristics is possible via (a) control of chemical nature of fixed groups at membrane surfaces, in order to weaken their catalytic activity with respect to water dissociation reaction, (b) increase in the surface hydrophobicity, and (c) design of electrical inhomogeneity of the membrane/solution interface; the purpose is the facilitating of intense development of electrical convection.

Concentration of Sodium Hydroxide Solutions by Electrodialysis

Several commercial ion-exchange membranes (FumaTech, DuPont) were tested in the electrodialytic oncentration of NaOH solutions in the range 1–5 M. It was found that the FumaTech cation-exchange membrane showed better performance than the bilayer Nafion membranes (DuPont) because of lower diluting effect caused by the electro-osmotic flow. However, neither of the tested membranes showed high enough efficiency for a practical application. The experimental results were modeled using the extended Nernst-Planck and Donnan equations. It was found that the derived model with two fitted parameters (effective fixed-charge concentration, tortuosity-porosity factor) satisfactorily describes the investigated process in the concentration range 1–4 M.

The Electrochemical Characterization of Ion Exchange Membranes in Different Electrolytic Environments: Investigation of Concentration and pH Effects

In this research, the effect of electrolyte concentration and environmental pH variations on electrochemical properties of two commercial heterogeneous ion exchange membranes was studied. Membrane structure investigation was carried out using the SEM method. Obtained images showed that the anion-exchange membrane possesses a rough surface while the cation-exchange one has mainly a smooth surface with effect on ions transportation ability. Membrane potential, transport number, and permselectivity were initially improved in cation-exchange membrane with an increase of electrolyte concentration from 0.1 to 0.5 M and then began to decrease with higher concentration increase from 0.5 to 1.0 M. Also, membrane potential, transport number, and permselectivity were decreased in anion-exchange membrane with increase of electrolyte concentration. Results revealed that cation-exchange membrane had higher potential, transport number, and selectivity at pH 7 and the anion-exchange one showed better performance at pH 10 compared to other pH values. Membrane resistance was decreased in both membranes due to increase of electrolyte concentration. Resistance also increased initially with increase of pH value but then began to decrease with higher increase in pH value. Membranes exhibited higher selectivity for monovalent ions compared to bivalent one. The results demonstrate that the anion-exchange membrane has lower selectivity and electrical resistance compared to the cation-exchange membrane.

Effect of Membrane Separators on the Performance of Direct Borohydride Fuel Cells

The effect of the separator type on the performance of laboratory direct borohydride fuel cells (DBFCs) using hydrogen peroxide as the oxidant, is studied at room temperature. Five commercial ion exchange membranes from Nafion (N117, 115CS, NRE-212) and IONAC (MC-3470, MA-3475) brands are considered as separators for the DBFC. The membranes are directly compared by the observation and analysis of the corresponding DBFC's performance. Cell polarization, power density, stability, and durability tests are used for the evaluation. Energy densities and specific capacities estimated for a 2-hour cell operation at 0.6 V are up to 45 Wh kg−1 and 76 Ah kg−1, respectively, when using a Nafion NRE-212 membrane separator. A peak power density of 96 mW cm−2, at 0.6 V and 160 mA cm−2, is reported for the DBFC using Nafion N117, but these values cannot be sustained for appreciable operation times. For long term cell operation the IONAC MC-3470 membrane seems to outperform the stability of the benchmark Nafion membranes. The IONAC membranes’ lower cost is a good motivation but further optimization is required to improve their instantaneous power load.

Salt splitting process application

The recovery of bases from solutions containing metallic salts were achieved in three compartment cells separated with commercial ion exchange membranes (IEMs) as anion exchange membrane (AEM) and cation exchange membrane (CEM). In the experiments, an equimolar quantity of acid, base and different salts of metal solutions were used as the anolyte and the catholyte solutions and the solution in the middle chamber of the cell, respectively. Effects of current, the type of ion-exchange membranes, the nature and the concentrations of the solutions on the recovery of bases were investigated. The results of the experiments were analyzed with the statistical package for social sciences (SPSS) program. The results obtained show that electrohydrolysis seems to be an applicable method for the recovery of bases from waste water at suitable conditions.

The Comparison of Two Different Electro‐Membrane Processes' Performance for Industrial Applications

AbstractThe recovery of bases from solutions containing salt forms of potassium was studied in cells separated by commercial ion exchange membranes. For this aim, two different types of techniques were applied. In the first technique, an equimolar quantity of acid solutions and different metallic salt solutions were used as an anolyte and a catholyte, respectively, in the cell separating with anion exchange membrane (AEM). In the second technique, an equimolar quantity of acid, base solutions, and different metallic salt solutions were used as an anolyte, a catholyte, and a solution in the middle chamber of the cell, respectively, in the cell separating with cation exchange membrane (CEM) and AEM. Effects of the current, the type of the membranes, the concentrations of the solutions, and the type of solutions on the recovery of bases were investigated and both of the techniques were compared. The results of the experiments were evaluated with the Statistical Package for Social Sciences program.

Fabrication and characterization of a carbon electrode coated with cation-exchange polymer for the membrane capacitive deionization applications

Abstract A carbon electrode coated with cation-exchange polymer was fabricated in a simple and inexpensive way for applications in membrane capacitive deionization (MCDI). A mixture of poly(vinyl alcohol) (PVA) and sulfosuccinic acid (SSA) was used as a coating solution to introduce negatively charged ion-exchange groups. The PVA/SSA-coated carbon electrodes were fabricated at different crosslinking temperatures and SSA contents. The prepared electrodes were characterized by SEM, FTIR analysis, cyclic voltammetry and electrical impedance spectroscopy. The PVA/SSA coating layer showed high adhesion to the carbon powders. The SSA was effectively introduced as a crosslinking agent and cation-exchange groups, as shown in the FTIR spectra. Cyclic voltammetry analysis indicated that the specific capacitance was increased by coating the carbon electrode with PVA/SSA polymer solution. The specific capacitances of the coated electrode were enhanced by 14.8–30.9% compared with the uncoated one, depending on the crosslinking temperature. The increased capacitance of the coated electrode is attributed to the fixed ion concentration in the PVA/SSA coating layer. The electric resistance and specific capacitance of the coated carbon electrodes were affected strongly by the crosslinking temperature due to the altered degree of crosslinking. The area resistances of the coating layer were in the range of 0.67–1.17 Ω cm 2 , depending on the crosslinking temperature and SSA content, which is relatively low when compared with commercial ion-exchange membranes.

Evaluation for Biological Reduction of Nitrate and Perchlorate in Brine Water Using the Hydrogen-Based Membrane Biofilm Reactor

Whereas ion exchange is an attractive technology for treating perchlorate and nitrate in drinking water, a major disadvantage is that the resin must be regenerated using a brine, producing wastes with high concentrations of nitrate, perchlorate, and salt. This study investigates the potential for simultaneous nitrate and perchlorate reductions in high-salt conditions using the H2 -based membrane biofilm reactor (MBfR). The autotrophic biological reductions produce harmless N2 and Cl− , making the brine safe for reuse or disposal. A very high-strength brine ( ∼15% salt) from a commercial ion-exchange membrane, Purolite, supported biofilm accumulation and allowed slow reduction rates for nitrate and perchlorate. Reduction rates increased significantly when the Purolite brine was diluted by 50% or more. A synthetic high-strength salt medium containing nitrate, perchlorate, or both supported more rapid reduction rates for as high as 20 g∕L (∼2%) NaCl , while 40 g∕L NaCl slowed reduction by 40% or more, confir...

Ion transport behavior in diffusion layer of new designed ion exchange-mosaic composite polymer membrane

New designed ion exchange-mosaic composite polymer membrane (MM/AEM) was proposed in this study. The new membrane was made from anionic exchange polymer gel (AEM) that coated onto mosaic polymer membrane (MM) to form MM/AEM polymer composite membrane system. Also, AEM membrane without mosaic membrane layer was used as reference commercial ion exchange membrane. The electrochemical properties of new designed composite polymer membrane system (MM/AEM) and non-composite one (AEM) were investigated by chronopotentiometry measurements (CP) and current–voltage curves ( I– V). In the presence of KCl solution, the limiting current density of new designed composite MM/AEM was higher than that of commerical AEM. In other words, at the same current density, the transition time of composite MM/AEM was shorter than that of commercial AEM, and also diffusion layer thickness ( δ), of composite MM/AEM was smaller than that of commercial AEM. It can be concluded that the new designed composite anionic exchange polymer membrane provides relatively good ion transport and other good membrane properties. In addition, the production of this new designed composite polymer membrane can be used in industry, like electrodialysis, as an alternative membrane instead of the commercial ion exchange membrane, which suffers from low limiting current density.

Removal of inorganic charged micropollutants in an ion-exchange membrane bioreactor

The transport of anionic drinking water micropollutants—perchlorate, nitrate and arsenate as well as that of a cationic micropollutant ionic mercury—through selected commercial ion-exchange membranes was studied under Donnan dialysis conditions in order to evaluate the possibility of using these membranes for pollutant removal in an ion-exchange membrane bioreactor (IEMB). The anion-exchange membrane, Neosepta ACS, proved to be a good choice for perchlorate and nitrate but was not suitable for arsenate, for which the Ionac MA-3475 allowed more than a three-order magnitude increase in flux. The cation-exchange membrane, Nafion-112, showed promising results for the transport of mercuric ions, while the Neosepta CMX was almost impermeable to this micropollutant. Tap water from the Lisbon public distribution network was supplemented with 100 ppb of perchlorate and 60 ppm of nitrate and was continuously treated in the IEMB incorporating a Neosepta ACS membrane for a period of about 2 months. Highly selective simultaneous removal of both pollutants was observed, in spite of their very different concentrations in the contaminated water. Secondary pollution of the treated water by microbial cells and residual organics was not found. Since the nitrate concentration in the treated water stream (<1 ppm) was always much lower than the EU recommended one of 25 ppm, the amount of water that can be treated in the system was dependent of the desired degree of removal of perchlorate, for which the US EPA suggests an acceptable concentration range from 4 to 18 ppb. The water treatment rate was about 3 L/(m 2h) when the objective was to achieve 4 ppb in the treated effluent (96% removal) but increased to 18 L/(m 2h) when the treated water contained the upper suggested limit of 18 ppb of perchlorate (82% removal).

Electrochemical characterization of poly(vinyl alcohol)/formyl methyl pyridinium (PVA-FP) anion-exchange membranes

To explore electrodialysis for purification of negatively charged large organic molecules (e.g., amino acids and medicine), water-swollen formyl methyl pyridinium-immobilized polyvinyl alcohol (PVA-FP) anion-exchange membranes were prepared and characterized in terms of their electrochemical properties. The PVA-FP membranes exhibited low electrical resistance (1.0–3.0 Ω cm 2), high swelling properties (water content ratio, 0.62–0.73), and reasonable transport number ( t ¯ − > 0.96 for Cl −). For glutamic acid solutions, the electrical resistance of the PVA-FP membrane was low (1.0–3.0 Ω cm 2) in a wide pH range, with no membrane fouling. Since the resonance effect of quaternary aromatic ammonium contributed to the structural stability of the PVA-FP membrane, the water-splitting with the PVA-FP membrane was approximately one order of magnitude lower than that with a commercial ion-exchange membrane at a same current density.

Modification and evaluation of membranes for vanadium redox battery applications

Several commercial ion exchange membranes were evaluated for application in the vanadium redox battery. The polyether membrane, DF120 cationic exchange membrane, showed the highest permeability to vanadium ions and the worst chemical stability in V(V) solution, while the divinylbenzene membrane, JAM anionic exchange membrane, showed the lowest permeability to vanadium ions and the best chemical stability in V(V) solution. In order to impart some cationic exchange capacity to the JAM anionic exchange membrane, sodium 4-styrenesulfonate was used to modify the anionic membrane by in situ polymerization. Measurements by infrared spectroscopy (IR) and cationic ion exchange capacity (IEC) verified that the modification procedure imparts cationic exchange capability to the membrane. Incorporation of cationic exchange groups to the anionic exchange membrane further results in a reduction in permeability to vanadium ions. The current and energy efficiencies averaged over 8 charge/discharge cycles of the cell with the treated JAM membrane were higher than that with the untreated JAM membrane. The current and energy efficiencies of the cell with the treated JAM membrane did not change over several charge/discharge cycles, which indicates good chemical stability of the treated membrane in the vanadium redox cell. The average efficiencies of the cell with the treated JAM membrane are higher than that with Nafion 117 over 8 charge/discharge cycles.

Characterization of charged film of fluorocarbon polymer (Nafion) and blended fluorocarbon polymer (Nafion)/Collodion composite membranes by electrochemical methods in the presence of redox substances. V

In order to get a better understanding regarding the structure of charged film of membranes, two kinds of the composite Collodion membrane (C), and Nafion one (N) were prepared and characterized by systematic and comparative studies. The Nafion (fluorocarbon polymer) and Collodion blended with Nafion in the ratio of (CN5:5) composite solutions were used to produce thin membrane films on Au electrodes. The present study indicated that better diffusion coefficient of redox substances can be achieved by blending the Nafion solution with ionic group to Collodion solution compared Nafion only. Diffusion coefficient of MV 2+ and FcDM in the blended Nafion/Collodion showed higher values compared to that Nafion. The uptake of neutral species of ferrocenedimethanol (FcDM), positively charged species of methyl viologen (MV 2+) and negatively charged of potassiumferrocyanide, [Fe(CN) 6] 4− ions were studied by cyclic voltammetry (CV), chronopotentiometry (CP) and chronocoulometry (CC). The diffusion coefficient values of MV 2+ of the blended composite, CN5:5 membranes are about twice (0.43 × 10 −6 cm 2/s) that of Nafion based membrane (0.27 × 10 −6 cm 2/s). While the diffusion coefficients of FcDM of the blended, CN5:5 and Nafion based membranes are in the order of 2.4 and 1.8 × 10 −6 cm 2/s, respectively. This means that the diffusion of positively charged species, MV 2+ was decreased in the membrane matrix compared to neutral species, FcDM. It also indicates that the concentrations of the MV 2+ are higher than that of the neutral species, FcDM, in both blended (CN5:5) and Nafion membranes. This may attributed to the existence of interaction between SO 3 − functional groups of fluorocarbon polymer and MV 2+ that led to mobility restriction of MV 2+compared to neutral FcDM one, i.e. diffusion of MV 2+ was decreased. It was found that the negatively species, [Fe(CN) 6] 4− exist in surface of the blended membrane (CN5:5) slightly, but not in Nafion one due to the electrostatic repulsion effect between SO 3 − functional groups of flourocarbon polymer and negatively species, [Fe(CN) 6] 4−. This means that diffusion of [Fe(CN) 6] 4− species was not clearly observed. As a whole, the blended membranes indicated membrane performance comparable to the commercial ion-exchange membranes.

ON THE KINETICS OF Cu, As AND Sb TRANSPORT THROUGH CATION AND ANION EXCHANGE MEMBRANES IN ACIDIC ELECTROLYTES

Experiments were conducted in a batch electrodialysis cell containing aqueous acidic solutions of copper, arsenic and antimony in order to evaluate their transport kinetics through commercial ion exchange membranes. A relatively high unwanted transport of bisulfate through the cation exchange membrane was observed with the transport rate being 0.39 mol/h/m2 at 225 A/m2. The bisulfate transport rate through the anion exchange membrane was found to be 1.05 mol/h/m2 at the same current density. The transport rate for the unwanted transfer of copper ions through the anion exchange membrane varied linearly with time and current density; the transport rates were 0.07 and 0.10 mol/h/m2 at 150 and 225 A/m2, respectively. These values were found to be lower than 1/7 of the transport rate of copper for both current densities, through the cation exchange membrane. Arsenic transport was found to be highly dependent on speciation. In a 1.5 mol/L H2SO4 solution, As(III) was transported as AsO+ with a rate of 0.02 mol/h/m2 at 225 A/m2 and As(V) was transported as H2AsO4 – with a rate of 0.01 mol/h/m2 in 0.5 mol/L of acid. At pH 2.8, the transport of As(V) increased tenfold to about 0.1 mol/h/m2. Antimony was transported through both anion and cation membranes at 2.7 and 3.4 mmol/h/m2, respectively. The transported cation is likely to be Sb(OH)2 + or SbO+ while the transported anions could be Sb(HSO4)m n− -type species.On a effectué des expériences dans une cellule à électrodialyse en lots contenant des solutions aqueuses acides de cuivre, d’arsenic et d’antimoine afin d’évaluer leur cinétique de transport au travers de membranes commerciales conductrices d’ions. On a observé un transport indésirable relativement élevé de bisulfate à travers la membrane conductrice de cations, à un taux de 0.39 mol/h/m2 à 225 A/m2. On a trouvé que le taux de transport du bisulfate à travers la membrane conductrice d’anions était de 1.05 mol/h/m2 pour la même densité de courant. Le taux de transport pour le transfert indésirable d’ions de cuivre à travers la membrane conductrice d’anions variait linéairement en fonction du temps et de la densité de courant; les taux de transport étaient de 0.07 et 0.10 mol/h/m2 à 150 et 225 A/m2, respectivement. On a trouvé que ces valeurs étaient 7 fois plus faibles que celles du taux de transport du cuivre pour les deux valeurs de densité de courant à travers la membrane conductrice de cations. On a trouvé que le transport d’arsenic était hautement dépendant de la spéciation. Dans une solution de 1.5 mol/L H2SO4, As(III) était transporté sous forme de AsO+ à un taux de 0.02 mol/h/m2 à 225 A/m2 et As(V) était transporté sous forme de H2AsO4 – à un taux de 0.01 mol/h/m2 dans 0.5 mol/L d’acide. À un pH de 2.8, le transport d’As(V) était décuplé à environ 0.1 mol/h/m2. L’antimoine était transporté à travers les deux membranes d’anions et de cations à 2.7 et 3.4 mmol/h/m2, respectivement. Le cation transporté sera probablement Sb(OH)2 + ou SbO+, alors que les anions transportés pourraient être des espèces du type Sb(HSO4)m n−.

Experimental and theoretical investigations of steady and transient states in systems of ion exchange bipolar membranes

The electrochemical characteristics of one commercial bipolar ion exchange membrane and of two home-made bipolar membranes are investigated over a range of current densities up to 2 kA m −2. Studies are performed using galvano-potentiometry ( i/ V) and impedance spectrometry methods. The temperature dependence of i/ V curves enables the determination of the activation energies related to the overall electrochemical process of H + and OH − production by water dissociation at the membrane junction. The physical analysis of the experimental data is made on the basis of a neutral layer model for the membrane junction. The theoretical treatment leads first to establish a thermodynamic framework insuring the validity of the criteria used in the interpretation of the results in terms of the model. Application of current electrochemical kinetic concepts at steady state involves the idea that, in the presence of an efficient catalyst, a quasi-reversible state of the water dissociation reaction may be achieved at the junction. A theoretical approach is developed for treating the data obtained with transient measurements in absence of co-ion transport. This study reveals the intrinsic roles played in the overall process of respectively: (a) the H + and OH − ion transport; (b) the electrical double layers at the membrane junction boundaries; and (c) the chemical mechanism of water dissociation.