Predicting adsorption of fluids confined to nanoporous media

Fluids confined to spaces of nanoscopic dimensions are found in zeolites, in stacks of clay platelets in soils and oil reservoir rock, between bilayered membranes, and between aggregating colloidal particles. Fluids adsorbed in nanopores have properties which differ dramatically from those of standard bulk phase systems. The aim of this thesis work is to carry out classical statistical mechanical theory and computer simulations on model nanoporous systems in order to advance our understanding of the equilibrium structure of adsorbed fluids confined to one, two and three-dimensionally periodic media. Xenon adsorbed in the zeolite mordenite is an example of a one-dimensional confined fluid. We can predict adsorption in such a system using the exact statistical mechanical theory of one-dimensional hard rods. Since all real systems have at least some multi-dimensional character, three-dimensional theories contribute added insights into confined fluid systems. We predict adsorption of xenon in zeolite A using the Tarazona model and the Generalized van der Waals model of free-energy molecular density functional theory. By using a trial function for the density distribution we can reduce the problem to one that is computationally tractable. We demonstrate the versatility of a model that is more general than the trial function model and use it to predict adsorption in zeolite NaA. We use grand canonical Monte Carlo simulations to predict adsorption of xenon in a set of two and three-dimensionally connected zeolitic pore structures. This work demonstrates the fundamental insights into adsorption that can be gained by using molecular theory in conjunction with experiments and computer simulations.