Electric-pulse layer-by-layer assembled of anion exchange membrane with enhanced monovalent selectivity

The present study investigates the electric-pulse layer-by-layer assembled of anion exchange membrane (AEM) by N-O-sulfonic acid benzyl chitosan (NSBC) and hydroxypropyl trimethyl ammonium chloride chitosan (HACC). The constructed NSBC/HACC layers by electric-pulse deposition method with 7.5 bialyers exhibit substantial influence on monovalent anions selectivity. The monovalent anion selectivity stems from an increased electrostatic repulsion effect for divalent anions and hydrophilic property of the membrane surface. Remarkably, the separation efficiency of Cl-/SO42- is increased from - 8.93% (unmodified AEM) to 94.43% (constructed 7.5 bilayers on the surface of AEM by electric-pulse deposition method) during 20 min and the permselectivity value is increased from 0.81 to 47.04. Compare to the traditional electrostatic deposition modification and the electro-deposition modification methods, the multilayer constructed by electric-pulse deposition technology with significantly homogeneous and stable monovalent selective separation multilayer. Besides, the modified AEM shows the higher selectivity than the commercial monovalent ion-selective AEMs.