title: Gas permeation through nanoporous membranes in the transitional flow region.
abstract: An experimental study on the permeability of anodic alumina (20-120 nm) and track-etched (30 nm) nanoporous membranes for different gases in the transitional flow regime is reported in the range of Knudsen numbers from 0.1 to 10. A significant variation (up to 30%) of the membrane permeance for different gases at the same Knudsen numbers is reported with certainty. It is established that this discrepancy relates to a molecule's effective collision area, which is poorly described in the frameworks of conventional gas permeation models. Two models are proposed for the description of the effect: self-diffusion of penetrate gases due to intermolecular collisions and enhancement of the slip flow contribution due to tangential momentum accommodation growth with the decrease of a molecule's effective collision area. The best fit parameters for the simultaneous fit of the experimental data with different models for 30 membrane-gas pairs are given.
authors.affiliation: Department of Chemistry, Moscow State University, Leninskie Hills 1-3, Moscow 119991, Russia. Physical-Technical Institute UB RAS, 132 Kirov Street, Izhevsk 426000, Russia.
authors.forename: D I
authors.initials: DI
authors.lastname: Petukhov
authors.forename: A A
authors.initials: AA
authors.lastname: Eliseev