MESOPOROUS MEMBRANES - THERMO-OSMOTIC AND ISOTHERMAL FLOWS WITH AND WITHOUT CAPILLARY CONDENSATION

Flow equations in differential and integral forms have been developed via the thermodynamics of irreversible processes for steady-state tran sport of a sorbable single chemical species through mesoporous membran es under conditions where capillary condensate and inhomogeneous fluid , which includes the Gibbs excess, co-exist in gradients of temperatur e and pressure. Criteria for the thermo-osmotic steady state of zero f low are considered and relationships are given between heats of transp ort of gas phase, inhomogeneous fluid and capillary condensate. Numeri cal values are tabulated for heats of transport of the inert gases, al kanes and other gases using carbon compacts of two different kinds. Th e heats are given and considered as functions of temperature (both dif ferential and integral values), and as functions of the initial pressu re prior to establishing the thermoosmotic steady state of zero flow ( the integral heats). Also considered is the determination of phenomeno logical coefficients, factors determining steady-state concentration p rofiles of inhomogeneous fluid and co-existing capillary condensate wi thin the membrane, and the role of capillary pressure in augmenting fl ow, especially for pervaporation.