Electrotransport of protons and chloride ions in anion exchange membranes for the recovery of acids. Part I. Equilibrium properties

Equilibrium properties of three anion exchange membranes were studied in aqueous solutions of HCl under symmetrical conditions. Measurements of exchange capacities, sorption, water content, electrical conductivity and self-diffusion flux of chloride ions showed that the classical gel-phase model does not account for the experimental data. So, we had to consider two simultaneous mechanisms of transport of Cl− ions: on the one hand, a hopping mechanism in the active region including the exchange fixed sites and the counter-ions, and, on the other hand, a dragging mechanism in the interstitial region. The mobility of the counter-ions balancing the exchanging sites increased with the HCl concentration in the external solution while that of the Cl− ions in the interstitial phase of the membrane remained practically constant.