Prediction of ion-exchange equilibria in binary aqueous systems

An iterative model for prediction of ion-exchange equilibria over a wide ra nge of total concentrations from one experimental isotherm has been propose d. Using thermodynamic parameters derived from the 0.2 N concentration of t he system Sr2+/Na+/ chabazite, the model was applied to predict isotherm va lues at 0.05 and 0.5 N. These predicted isotherms, together with experiment al points measured at 0.05 N in order to check the prediction, showed excel lent agreement and indicated that the theory applied to the prediction of b inary equilibrium data is sound and that the iteration procedures work well . Also, the applied model has been tested by using two different ion-exchan ge systems namely; clinoptilolite and Sr2+/Na+ mordinite. Because the thermodynamic model in this study can be easily extended to ter nary and more complicated mixtures, it may be useful for modeling ion-excha nge equilibria in multicomponent geochemical systems.