Application of regular solution theory to calculation of liquid—liquid equilibria for water-containing systems

Abstract

In this paper, based on regular solution theory, a general equation for the calculation of different kinds of liquid—liquid equilibria (LLE) containing water is developed. A mixing entropy term and a long-range electrostatic term are introduced. A relationship between the interaction parameter and the absolute temperature is proposed. It can be used to correlate the LLE data for water—organic binary systems with upper and lower critical solution temperatures. The general equation has a wide application to LLE containing water—organic and water—electrolyte binary systems, as well as water—organic—organic and water—organic—electrolyte ternary systems. A simple equation for predicting the critical composition for binary LLE is deduced.