The application of membrane distillation for the concentration of oil-water emulsions

In this paper we compare the properties of anion-exchange membranes in contact with aqueous solutions containing zinc chloride complexes and with uncomplexed metal chloride solutions. Electric resistance measurements were performed as a function of the composition of the external solutions, which are mixtures of hydrochloric acid with sodium, zinc or nickel chloride. The transport numbers of proton and zinc through anion-exchange membranes were measured, and the obtained results showed the influence of the complexed species on the loss of permselectivity of the studied membranes. These results were analyzed on the basis of Raman spectra of the membranes equilibrated with the considered solutions.