Prediction Method of Salt Effect on Vapor-liquid Equilibria by Solvation Model

Abstract

A prediction method is presented for salt effect on vapor-liquid equilibria by a solvation model. The solvation model assumes that the activity coefficient for vapor pressure depression has additivity with each activity coefficient of each solvent in pure solvent+salt system. In this work, to describe more accurately the behavior of the activity coefficient which contributes to the vapor pressure depression, the solvation model introduces a correction factor for estimation of the activity coefficient for vapor pressure depression. The introduced function with correction factor has the following characteristics; (1) peak activity coefficients can be expressed, (2) no correction is done for pure components, and (3) extension to a multi-component system is possible. As a result, the presented method improves the prediction accuracy of vapor pressure depression or boiling point raising of binary solvent mixture+salt systems and boiling point of ternary solvents+salt systems by using the correction factor determined from a binary solvents+salt system. © 2000, The Society of Chemical Engineers, Japan. All rights reserved.