Elecrtochemical Investigation of Heterogeneous Cation-Exchange Membranes Modified by Polyanilin in Solutions of Monovalent and Divalent Cations

Abstract

A series of composite ion-exchange membranes based on a heterogeneous cation-exchange MK-40 membrane and polyaniline was obtained under the conditions of electrodiffusion of a monomer and an oxidizing agent. The process of polyaniline synthesis on the membrane surface was accompanied by the registration of chronopotentiograms and the pH of the solution leaving the desalination compartment. The initial MK-40 cation-exchange membrane and the composites based on it were studied by voltammetry and chronopotentiometry in NaCl, CaCl2, and MgCl2 solutions in the same electrodialysis flow cell in which the composites were obtained. To calculate the transport numbers of counterions in membranes in CaCl2 and MgCl2 solutions by the chronopotentiometric method, the apparent fraction of the conducting membrane surface in the NaCl solution was calculated based on experimental data on the potentiometric transport numbers of counterions in the membrane. The conditions for the synthesis of polyaniline on the surface of a heterogeneous MK-40 membrane, leading to the preparation of samples with selectivity to singly charged ions, are revealed.