Ternary Ion-Exchange Equilibria

Abstract

The shape of parametric lines in both phases of ternary ion-exchange systems are discussed for both ideal and nonideal systems. It has been shown that deviations of the parametric lines from linearity correspond to nonideality of the system while the converse is not necessarily valid. Conditions of linearity for nonideal systems are derived. Equations for calculating activity coefficients of resinates in ternary mixtures are given. Triangular diagrams and three-dimensional diagrams of the dependence of activity coefficients on composition are illustrated by the systems NH₄ ⁺-Na⁺-H⁺ and Ba⁺-Cu²⁺-Co²⁺ on sulfostyrene-type exchangers. Methods for prediction of ternary ion-exchange equilibria are discussed. A comparison of these methods for the systems studied shows that consideration of the nonideality of the systems is required for accurate prediction.