MEMBRANE-TRANSPORT PROPERTIES OF PERVAPORATION AND VAPOR PERMEATION IN ETHANOL-WATER SYSTEM USING POLYACRYLONITRILE AND CELLULOSE-ACETATE MEMBRANES

Although permeation flux in PV and that in VP at saturated vapor pressure in feed should theoretically be equal, results obtained so far are contradictory. In the present work, theoretically predicted behavior of transport properties in PV and VP were first examined, based on the permeation equations developed in the previous paper, in particular for ethanol-water system. Next, experiments in PV and VP were performed in this system to check the conclusions obtained above using PAN and CA membranes. Results with PAN membranes showed good agreement between PV and VP, but the results with CA membranes showed larger permeation flux and a lower separation factor for water in PV than in VP. From observation from outside the cell, wrinkles on membrane surfaces were seen in PV experiments, but were not observed in VP experiments. Since the amount of sorption of solution in CA membranes is large, small difference in swelling conditions during experiments between PV and VP can have a large effect on the permeation fluxes.