A “free volume” model of permeation of gas and liquid mixtures through polymeric membranes

✍ Scribed by S.-M. Fang; S.A. Stern; H.L. Frisch

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 801 KB
• Volume: 30
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(75)80041-8

✦ Synopsis

A recent "free volume" model of gas permeation (3) has been extended to the transport of gas mixtures through nonporous polymeric membranes. The present model assumes that the rates of transport of the components of a mixture depend on the free volume of the gas-polymer system, and that the effect of these components on the free volume is additive. The latter assumption limits the model to relatively dilute systems, with total penetrant concentrations of perhaps less than 0.2 volume-fraction. The prediction of permeation fluxes and permeability coefficients requires the knowledge of specified free-volame parameters which can be determined from measurements of diffusion coefficients and viscosities of the pure penetrant-polymer systems. When the systems are sufficiently dilute to obey Henry's law, the permeability coefficients for fhe components of a gas mixture can be predicted using only permeability measurements with the pure components. The extended free-volume model can be applied also to the permeation of liquid mixtures. The theoretical predictions are compared with the results of several experimental studies, and the potential usefulness and limitations of the model are discussed.