Vapor−Liquid Equilibria and Interfacial Tensions of Associating Fluids within a Density Functional Theory

A self-consistent density functional theory is applied to investigating the phase behavior and interfacial tensions of water and low-molecular-weight normal alkanols. For the bulk phases, the density functional theory is reduced to an equation of state that provides an accurate description of saturation pressures as well as vapor−liquid phase diagrams. Near the critical region, the long-range fluctuations are taken into account using a renormalization group theory. With the same set of molecular parameters, the theory yields satisfactory results for both bulk properties and surface tensions of the associating fluids investigated at all temperatures.