Influence of Membrane Properties on System Performances in Pervaporation under Concentration Polarization Regime

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Abstract
The concentration polarization phenomenon was studied in the case of the dehydration by pervaporation of octanol in relatively concentrated solutions (up to 47000 ppm of water in n-octanol). The dependence of the observed performances on the mass transfer properties of the membrane and the boundary layer is analyzed theoretically. Experiments performed with cellulose acetate membranes of different thicknesses at a variable stirring speed in an agitated cell allowed us to determine the parameters of the theoretical model. It appears that the selectivity in pervaporation may depend in a complex way on the mass transfer in the boundary layer due to the possible concentration-dependent coupling of fluxes in the membrane. Results of the simulations of situations in which the membrane characteristics as well as the mass transfer in the liquid phase were changed are given to illustrate the influence of different parameters on the observed performances.