Influence of the model for describing the Debye-Hückel term in phase equilibria involving electrolytic systems

Abstract

The aim of this article is to evaluate the influence of the model used to describe the Debye-Hückel term in predicting phase equilibria involving electrolytic systems. To this end, the bubble point for the system (sulfur dioxide – water) was evaluated using the Debye-Hückel models proposed by Sander et al. (1986) and Pitzer (1980). Thermodynamic models describing electrolytic systems have different characteristics to models for traditional solutions, because these solutions have an electrical charge in the liquid phase. Therefore, in order to model phase equilibrium, the non-idealities of the liquid phase will be described by the Pitzer equation of state and the non-idealities of the vapor phase will be described by the virial equation of state. The thermodynamic model for predicting phase equilibrium was implemented in Fortran 90. The results show that the two models are capable of describing the system studied, since the average deviations between the simulated and experimental data are 8.48% for Sander et al. (1986) and 3.90% for Pitzer (1980).