Modification of the extended UNIQUAC model for ternary and quaternary liquid-liquid equilibrium calculations

Abstract

In predicting the liquid-liquid equilibria of ternary mixtures using common excess Gibbs free energy models with only binary parameters, the inaccuracy of prediction has been observed in many cases. A thermodynamic method to overcome this problem is presented here. It is shown that a good correlation of the ternary liquid-liquid equilibria of strongly nonideal mixtures is possible using the extended UNIQUAC model through the inclusion of ternary parameters attributed to unlike three-body interaction. The proposed method is straightforwardly extended to quaternary (or multicomponent) mixtures.