Observations on an equation of state for water confined in narrow slit-pores

Water may be adsorbed in microporous or mesoporous materials from the liquid phase or from the gaseous, or vapor, phase. In either case, the fluid state of the adsorbed water molecules may be liquid or vapor as well, depending on several factors inherent to the adsorbate itself. This work sought to understand these factors using an equation of state reported in the literature recently. It was determined that the model’s predicted contribution of the hydrogen bonding to the Helmholtz free energy was less than expected. The estimation of the magnitude of hydrogen bonding appears to be more realistic if positive contributions of four neighbors is included rather than one. The model also appears to involve quite sensitive calculations, which may be prone to precision errors.