RESISTANCE MODEL APPROACH TO ASYMMETRIC POLYETHERIMIDE MEMBRANES FOR PERVAPORATION OF ISOPROPANOL/WATER MIXTURES

The resistance model approach to asymmetric membranes for pervaporation was attempted. It was shown that the selectivity achievable in an asymmetric membrane is influenced not only by the relative resistance of the skin layer and the substrate but also by the relative resistance of the polymer matrix and the pores in the substrate. Based on this approach, the pervaporation data of the asymmetric polyetherimide membranes for the separation of isopropanol/water mixtures were analyzed, and the resistances lying in the path of mass transport through the membranes were quantified on a relative basis. The intrinsic permeability data involved in the resistance model were determined by conducting pervaporation experiments with a dense membrane. The asymmetric membranes used here were not prepared under optimum conditions, but membranes of better performance can be obtained by appropriate control of the preparation parameters.