Modeling of interfacial properties of multicomponent systems using density gradient theory and PCP-SAFT

The perturbed-chain polar statistical associating fluid theory (PCP-SAFT) and density gradient theory are used to calculate interfacial properties of multicomponent systems. The constant influence parameters are adjusted to experimental surface tension data of pure fluids and the cross-influence parameters are determined from a geometric combining rule. The influence parameters of simple branched alkanes, in the absence of experimental surface tension data, can be estimated from a correlation for n-alkanes. Results for surface tension of hydrocarbon mixtures of up to twenty components as well as systems including polar and supercritical species are in good agreement with experiments as long as bulk densities are reproduced accurately and molecular interactions between the components are symmetric or only weakly asymmetric.