INFLUENCE OF CATIONS ON THE PROTON LEAKAGE THROUGH ANION-EXCHANGE MEMBRANES

In the recovery of acids from wastewaters or the regeneration of acids and bases from salts by electromembrane processes, the most important phenomenon which limits the current efficiency is the transport of pr otons through the anion-exchange membrane (AEM). In this work, the pro ton leakage through an AEM is studied with a system containing hydroch loric acid or sulfuric acid on the cathodic side and the mixture of ac id with one homoanionic salt (Li+, Na+, K+, Cr3+, NH4+, (CH3N+ and (C2 H5N+) on the anodic side. The proton leakage is quantified from the va lue of the proton transport number. The results are analyzed assuming that the rate determining step of proton leakage is the interfacial tr ansfer reaction of protons from the aqueous anodic solution to the mem brane. The proton leakage is enhanced by the polarizing power of the c ation. The transfer of protons into the membrane seems to be catalyzed by the presence of a layer of adsorbed cations on the surface of the membrane. The presence of salt decreases the proton leakage but it is always greater with H2SO4 solutions compared to HCl solutions.