Microscopic Structure of the Membrane

The membranes of practical usefulness arc, on the other hand, prepared by the phase-inversion technique. We have learned that the top selective layer of the asymmetric membrane prepared by the phase-inversion technique has a microscopic structure that depends on the conditions under which the membranes are prepared. Obviously, Che numerical parameters associated with the membrane transport equations should depend on the microscopic structure of the membrane and also on the conditions under which membranes are prepared. 

The differences between the surface force-pore flow model and the solution-diffusion model are (1) the microscopic structure of the membrane is incorporated explicitly into the transport equations as the pore radius in the surface force-pore flow model (2) the interaction force working between the permeant and the membrane is also incorporated into the transport equations as an interaction force parameter in the surface force-pore flow model (3) as mentioned in Chapter 5, the solution-diffusion model describes the transport of permeants through the membrane, as an uncoupled diffusive flow. Mass transfer by the diffusive flow is expressed by a set of transport parameters that are intrinsic to the polymeric material. Any flow other than the above intrinsic diffusive flow is... 

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