Separation of H2SO4+ZnSO4 mixture by diffusion dialysis

Dialysis of an aqueous solution of H2SO4 + ZnSO4 was investigated in a two-compartment cell with an anion-exchange membrane, Neosepta-AFN. The experiments proved that sulfuric acid permeates well through the membrane while zinc sulfate was efficiently rejected. This operation is very effective at high acid concentrations and low concentrations of zinc sulfate. The flux of ZnSO4 calculated from the time dependencies of the ZnSO4 concentration was negatively influenced by increasing acid concentration. It was demonstrated that (1) the ZnS4 concentration in the membrane decreased with increasing acid concentration and (2) at the same time, the concentrations of zinc complexes bearing negative charges also decreased.