Gas and vapor permeation through polymer membranes.

Abstract

The permeation data of CO$\sb2$/CH$\sb4$ mixtures through cellulose acetate membranes were analyzed. The pore flow model initially used for pure gas permeation was extended to the permeation process of gas mixtures. The permselectivity calculated using the model was compared with the experimental data, and the results showed the applicability of the model to the description of gas mixture permeation process. The effects of feed composition, operating pressure and the pore size of the membrane on the permeability and selectivity of the membrane were determined and interpreted on the basis of the pore flow model. The separation of organic vapors from air was attempted by means of polyimide membranes at ambient temperature. The membranes were prepared by a phase inversion technique and then dried using a solvent exchange method. The experimental results show that the permselectivity depended on the porous structure of the membrane which can be controlled by the membrane making conditions. The effects of several parameters involved in the procedure for membrane preparation on membrane performance were determined.