Binary associating fluid mixtures against a hard wall: density functional theory and simulation

We present an extension of our perturbation density functional (DF) theory [SEGURA, C. J., CHAPMAN,W.G. and SHUKLA, K.P., 1997, Molec. Phys., 90, 759], which applies the weighting from Tarazona's hard sphere density functional theory to Wertheim's bulk first-order perturbation theory, to form a perturbation density functional theory for binary associating hard sphere fluid mixtures. Monte Carlo simulation results of a binary mixture of equal-sized hard spheres with one component having four associating sites placed in the Bol [1982, Molec. Phys., 45, 605] fashion are presented to compare with the theory. Comparison of theory and molecular simulation for the separation factor, component density profiles and fraction of monomers (associating component) show good agreement. Good to excellent accuracy are obtained for the densities and temperatures studied.