CONCENTRATION POLARIZATION IN GAS PERMEATION

The aim of this article is to show the importance of concentration pol arization effects in the separation of gas-vapor mixtures using membra nes. In the experimental part of this work, gas mixture measurements a re conducted with a specially designed test cell. The experimental dat a are analyzed using a two-resistance model for the transport through the membrane, which is derived in the theoretical part of this work. T he two resistances considered are the transport through the boundary l ayer on the feed side of the membrane and through the separation layer . For the transport through the separation layer an extended free volu me model is derived. This model considers not only the feed side but a lso the influence of the permeate side on the separation properties of the membrane. The results of the measurements show the influence of c oncentration polarization effects and their dependencies on feed press ure, membrane thickness, and feed flow rate. (C) 1998 Elsevier Science B.V. All rights reserved.