Correlation and prediction of interface tension for fluid mixtures: An approach based on cubic equations of state with the wong-sandler mixing rule

Abstract

Concentration profiles, interface thickness, and interface tensions have been calculated for mixtures applying the gradient theory to the Peng-Robinson equation of state. The approach is based on an accurate local fit of vapor-liquid equilibrium (VLE) data, and, for this purpose, the flexibility of the original Wong-Sandler mixing rule has been taken into account. Correlation and prediction capabilities of experimental interfacial tension data are analyzed for the quadratic mixing rule and the present approach. The method, which is discussed in detail in this work, provides an improved scheme for calculating interfacial properties, both for polar and nonpolar mixtures. According to results, a better correlation and prediction of the interfacial tensions can be obtained from an adequate interpolation of the VLE, using simple cubic equations of state. Examples are presented for binary and ternary mixtures.