(715c) Using Dynamic Mean Field Theory to Study Non-Equilibrium Steady States in Mesoporous Membranes

Mesoporous membranes contain pore sizes technologically relevant to separation of mixtures such as CO₂ from effluents and volatile organic compounds from air. Design of these materials requires understanding of the underlying transport of gases and condensable vapors in pure as well as mixture form through mesopores. Processes associated with these membranes, whether it is measurement of pore size distribution or separation of gases, are inherently non-equilibrium as a result of presence of partial pressure gradients. Continuum modeling for such a process requires predetermined models for confinement effects while atomistic simulations are computationally intensive. We study these systems with dynamic mean field theory (DMFT), a coarse grained lattice based theory, which has been successfully applied in the past to study relaxation dynamics of systems in approach to equilibrium steady state. We recently published a computational study of permporometry, an experimental technique used for determination of pore size distribution, where a light gas permeates in presence of condensable vapor. This system is akin to transport under conditions with slight deviation from equilibrium. We have further applied DMFT to the separation of condensable vapor from its mixture with light gas under significant pressure gradient which represents a large deviation from equilibrium. Both these studies reveal interesting phenomena such as higher flux of the light gas in the layer adjacent to the strongly adsorbed surface layer in the first case while latter system shows capillary condensation confined to high pressure side of the system.