When a salt is added to an azeotropic mixture, the azeotropic composition tends to shift or even disappear, due to salt-in and salt-out effects. Models from the literature are applied to calculate the vapor-liquid equilibrium of systems of isopropyl alcohol H2O-salt, and methanol H2O-salt. Schmitt and Vogelpohl's model (1982) gives the best results. With the concept of preferential association, an improvement can be accomplished through the modified distribution factor of the salt associating with components of the mixture for the systems mentioned above. Owing to the lack of solubility data of the salt in the individual components of the azeotropic mixture, the generality of this modification has not yet been demonstrated.
