Vapour-liquid equilibrium for mixed-solvent - strong electrolytes mixtures with EoS/GE models

Abstract

In this work, the ϕ-ϕ approach is used to describe the behaviour of vapour-liquid equilibrium of mixed-solvent electrolyte solutions by means of EoS/GE type models. The approach in this article consists in the inclusion of activity coefficient information in the Peng-Robinson equation of state through three different mixing rules: Heidemann-Kokal (HK), LCVM (Linear Combination of Vidal and Michelsen) and Wong-Sandler (WS). The significance of the inclusion of an electrostatic term, from the Debye-Hückel Theory, is also evaluated. An extensive database, containing 57 mixed-solvent-strong electrolyte solutions, is revisited and a parameter estimation strategy proper to be applied in large data sets is proposed. As result, it is shown that this type of model is very successful in the vapour-liquid equilibrium calculations for salt concentrations up to 13 molal, and that the electrostatic term has little significance in this application when the UNIQUAC parameters are re-adjusted.