Liquid–Liquid Equilibrium and Interfacial Tension of Hexane Isomers–Methanol Systems

Liquid–liquid equilibrium (LLE) and therefore interfacial tension are highly dependent on molecular architecture. In processes, where branched molecules are involved, these properties often cannot be measured; therefore, there is a need for thermodynamic modeling to make these properties accessible. A methodology, which allows for the prediction of liquid–liquid equilibria of systems containing branched molecules, was developed recently, where the lattice cluster theory is combined with the chemical association lattice model. In this contribution, it was proved whether the methodology can consider small changes in molecular architecture. Therefore, binary LLE of methanol and four hexane isomers were estimated and predicted. All predicted LLE showed a very good agreement with the experimental data. Additionally, the interfacial tension and interfacial concentration profiles were estimated for the investigated systems and calculated by the density gradient theory. For that, its influence parameter was adjusted to a single data point.