Ternary liquid—liquid equilibria: the van laar equation

Abstract

The capabilities of the three suffix van Laar equations in predicting the more complex types of ternary liquid—liquid phase diagrams have been examined. While the limitations enforced by thermodynamic consistency on the binary parameters seriously affect the quantitative accuracy with which correlations can be achieved, the van Laar equations are capable of describing qualitatively a variety of complex phenomena. In the system water, n-hexane, phenol, the eruption of a three liquid phase region inside a binodal curve as temperature is decreased is accounted for by the van Laar equation. The similar eruption of a three liquid phase region inside a band in the system glycol, lauryl alcohol, nitroethane is also described. A variety of other types of computed phase diagrams, all of which (save one) have experimental counterparts, are presented. It is also shown that the van Laar equation is capable of quantitatively correct correlation of data for some selected simple systems.