A Modification of UNIQUAC Model for Electrolyte Solutions Based on the Local Composition Concept

Abstract

In the present study, a thermodynamic model is developed to predict the phase equilibrium of electrolyte solutions. In this model the Pitzer–Debye–Huckel equation was used to calculate the long-range contribution of the activity coefficient. To take into account the short-rang part of activity coefficient a new modified UNIQUAC-based model was developed. The model was applied for 18 binary electrolyte solutions. Results show that the model presented reproduces the osmotic coefficients of electrolyte solutions accurately to high concentration levels of salt. Comparison of standard deviation of the model and E-NRTL and E-UNIQUAC-NRF models was performed in the manuscript.