New homogeneous and bilayer anion-exchange membranes based on N,N-diallyl-N,N-dimethylammonium chloride and ethyl methacrylate copolymer

Use of electrochemical impedance spectroscopy to assess the stability of the anion exchange membrane MA-41, modified by poly-N,N-diallylmorpholine bromide in overlimiting current modes

“…The significant discrepancy between the experimental and theoretical limiting current densities for the MA-41 membrane is attributed to the heterogeneity of the membrane's surface, where non-conductive areas of polyethylene reduce the active surface area [13,24,25]. The fact that the limiting current value for the modified membrane is also significantly lower than the theoretical value indicates that poly-N,N-diallylmorpholine does not form a continuous film on the membrane-substrate surface.…”

“…Additionally, the intensive water dissociation reaction reduces the space-charge density at the membrane/solution interface and suppresses the development of electroconvection [5,11,12]. Therefore, it is crucial to increase the electrochemical stability of ionexchange groups in anion-exchange membranes and reduce the intensity of water dissociation at the membrane/solution interface [13].…”

The Effect of Bulk Modification of the MF-4SK Membrane with Phosphorylated Hyper-Branched Dendrimer Bolthorn H20 on the Mechanisms of Electroconvection/Dissociation of Water and Specific Selectivity to Divalent Ions

“…In underlimiting current regimes, it is conventionally assumed that ion transport is purely electrodiffusive, and the ion flux through the membrane linearly depends on the current density. However, recent studies have noted that, in addition to electrodiffusion, underlimiting current regimes may exhibit effects of equilibrium electroconvection [44][45][46], characterized by an excess of the experimentally determined limiting current in an electromembrane system over the theoretically calculated value. This ion transport is associated with the electroosmosis of the first kind (as per the classification of Dukhin-Mishchuk [47]) and is not electrodiffusive.…”

“…Zabolotskiy et al [46] proposed a methodology to assess the contributions of different mechanisms to the overall mass transfer in an electromembrane system. Assuming that in the underlimiting current regime, ion transport occurs either solely through electrodiffusion or through both electrodiffusion and equilibrium electroconvection, the contribution of the latter to the limiting current can be found to be the difference between the experimental limiting current and the theoretical value calculated using the Pierce equation:…”

“…The high catalytic activity of membranes containing phosphorylated Boltorn H20 in the water-splitting reaction suggests that they could be effectively used as the cation-exchange layer of a bipolar membrane. The anion-exchange layer, in turn, could be made of a copolymer of DADMAC and ethyl methacrylate (this material is extensively described in [46]), as previously developed by the authors. The thickness of the anion-exchange layer and the thickness of the cation-exchange layer were 200 µm.…”