Uptake of electrolytes by cellulose acetate membranes

• Published in: Desalination Vol. 46; no. 1-3; pp. 417 - 423
• Main Authors: Mossa, G., Passino, R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.1983
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/0011-9164(83)87184-7

The distribution in cellulose acetate (CA) membranes of a solution of two electrolytes with a common anion has been studied. The system composed of a generic acid HxAn and a generic symmetric salt MeAn has been studied and a theoretical model based on Donnan and dielectric exclusion Phenomena has been developed. This model can be used to obtain the patterns of Me+x counterion and An−x coion distribution coefficients as a function of external salt concentration. Satisfactory agreement has been found between theoretical and experimental patterns for both HCl + NaCl and H2SO4 + + NISO4 systems. The most significant fact is the strong effect of external solution pH on the distribution coefficients. The system composed of the two salts ABx + DBx has also been studied. Also in this case a quantitative model has been developed to predict the patterns of the distribution coefficients of the two cations A+x and D+x as a function of the ratio between the concentrations of the two salts. Particular attention has been focussed on the effects of salt distribution coefficients and cations valency on cation distribution coefficients in the case of ZnCl2 + CuCl2 and CrCl3 + FeCl3 systems. Metal separation efficiency in the distribution process increases as the metalls valency increases.