MODEL FOR PREDICTING THE EFFECT OF DISSOLVED SALT ON THE VAPOUR LIQUID EQUILIBRIUM OF SOLVENT MIXTURES.

Abstract

A model describing the vapor liquid equilibrium of a mixture of solvents containing a dissolved salt was derived along similar basis as that used for the derivation of the Wilson equation for salt-free systems. The proposed model contains two groups of parameters - one set is the same as that defined by Wilson for solvent-solvent interaction in salt-free systems and the other set describes the salt-solvent interaction which can be easily calculated from the bubble points of the individual solvent components containing the given salt at the system pressure. Using the appropriate documented Wilson's solvent-solvent parameters for the salt-free system and the computed values of salt-solvent parameters from bubble point data, the vapor liquid equilibrium predicted by the model was found to compare satisfactorily with the experimental data for 57 different binary alcohol-water systems containing different salts at different concentrations.