Effect of cation-exchange layer thickness on electrochemical and transport characteristics of bipolar membranes

Electrochemical Properties of Homogeneous and Heterogeneous Anion Exchange Membranes Coated with Cation Exchange Polyelectrolyte

“…In the case of IEM, for redox flow batteries, layered polyelectrolyte composite membranes showed good conductivity and low permeability to vanadium ions [6], and a thorough review of methods to achieve high monovalent selectivity of IEM in the separation processes (including several techniques for coating surfaces with charged and uncharged layers) was recently published [7]. Surface modification of ion exchange membranes with polyelectrolytes was used for pH correction [8], for suppression of fouling [9,10] or scaling [11], and for facilitation of the electro-osmotic slip of water near the surface [12]. It was shown that excellent monovalent selectivity can be achieved for IEM using layer-by-layer coating with polyelectrolytes carrying functional groups of alternating charges [13,14], or even for multilayers applied at uncharged porous supports [15].…”

Synthesis of New Hyperbranched Phosphorus-Containing Polyesters Starting from Boltorn H20

“…The main limitation of a more common use of ABM-based electrodialysis for pH adjustment processes in solutions is the high overvoltage across ABMs operating in the hydrogen and hydroxyl ion generation mode. To overcome these disadvantages and improve the electrochemical properties, a method of ABMs modification by introducing ionic polymers with catalytic activity in water dissociation into the bipolar region was proposed [1][2][3][4][5][6][7]. Hyperbranched polymers such as Boltorn H20 are promising precursors for these catalysts.…”

Modification of asymmetric bipolar membranes by functionalized hyperbranched polymers and their investigation during pH correction of diluted electrolytes solutions by electrodialysis

“…Research on the effect of modifying film thickness on the electrochemical and functional characteristics of the asymmetric bipolar membranes was carried out in works [14][15][16][17]. Xu and co-authors [14][15][16] analyzed the effect of the thickness of monopolar layers on molecular transport of water and water splitting reaction.…”

“…Bipolar membranes with asymmetric layers have higher osmotic permeability and effectiveness than the traditional bipolar membranes with monopolar layers of identical thickness. Using the voltamperometry and electrochemical impedance spectroscopy methods to study the asymmetric bipolar membranes with a different thickness of homogeneous cation-selective film authors [17] have shown that the functional properties of reaction of water dissociation can be comparable to each other. At the same time, the desalination process is accompanied by pH correction of the solution.…”

“…At the same time, the desalination process is accompanied by pH correction of the solution. Furthermore, authors in [17] studied the effect of the cation-exchange layer thickness on total and Ohmic electrical resistances of asymmetric bipolar membranes. It was established that the contribution of Ohmic resistance to the total resistance of all analyzed asymmetric bipolar membranes (taking into account the reaction of water dissociation on the bipolar border) did not exceed 5 %.…”