Modeling of Interfacial Tensions of Long-Chain Molecules and Related Mixtures Using Perturbed Chain-Statistical Associating Fluid Theory and the Density Gradient Theory

Long-chain compounds such as fatty-acid methyl esters and fatty alcohols are often based on renewable sources and are widely used in soaps and as surfactants. Hence, the knowledge of their pure-component surface tensions and interfacial tensions against water is indispensable. As experimental data of these systems are scarce, a simultaneous and preferentially predictive thermodynamic modeling of phase equilibria and interfacial properties is desirable. In our previous works (Haarmann et al., Ind. Eng. Chem. Res. 2019, 58 (7), 2551–2574 and Haarmann et al., Ind. Eng. Chem. Res. 2019, 58 (11), 4625–4643), the focus was on the description of the phase equilibria of pure long-chain compounds and their binary mixtures with water using a homosegmental as well as a newly introduced heterosegmental approach of the Perturbed Chain Statistical Associating Fluid Theory. Here, both approaches were combined with the Density Gradient Theory in order to obtain interfacial properties. When the combined models were applie...