Nonlocal Density Functional Theory and Grand Canonical Monte Carlo Molecular Simulations of Water Adsorption in Confined Media

We present a study of water adsorption behavior in confined media by using on the one hand a nonlocal density functional theory (NLDFT) coupled with the statistical associative fluid theory for potential of variable range (SAFT-VR) equation of state and, on the other hand, grand canonical Monte Carlo (GCMC) molecular simulations. The present work is a second step in an ongoing NLDFT/SAFT-VR coupling. The first step has focused on the monomer contribution and especially on the way to extend the dispersive terms of the monomer contribution of SAFT-VR in the NLDFT formalism. In the present work, the theory has been extended by introducing the associating contribution due to hydrogen bonding and is applied to water, which is modeled as one sphere with four identical associating sites placed in a tetrahedral geometry with the same interaction parameters for both theory and simulations. NLDFT/SAFT-VR and GCMC results for density distributions of water in graphitic slit-like micropores and mesopores are shown to be in good agreement. Moreover, the capillary condensation and evaporation were investigated with the theoretical model in micro- and mesopores and also in the case of activated surfaces.