Ion exchange equilibrium between ion exchange membrane and electrolyte solutions

The ion exchange equilibrium between an ion exchange membrane and solutions of different electrolytes was studied. The matrix of the ion exchange membrane used consists of a vinyl polychloride network reinforced by a polyester screen; with quaternary and tertiary ammonium as functional groups. The data, provided by manufacturer, were completed by the experimental determinations of humidity percentage and ion exchange capacity. This paper focuses on the study of exchange reaction between an anion exchange membrane and selected binary and ternary electrolyte solutions. Experimental data are reported for the ion exchange equilibrium of the binary system Cl-/ NO3-, Cl-/SO42-, NO3-/SO42- and the ternary system Cl- - NO3- - SO42-. The ion exchange isotherms were established and affinity order of ions was given. The prediction of the ternary system based only on the binary data was consistent with the experimental data obtained for this system. Selectivity coefficients K-Cl-(NO3-), K-2Cl-(SO42-), K-2NO3-(SO42-) were determined at ionic strength 0.1 M. Ion analyses were performed by ion chromatography, coupled to a conductimetric detector.