Thermodynamic Insights into the Characteristics of Unary and Mixture Permeances in Microporous Membranes.

ABSTRACT: The primary objective of this article is to gain fundamental insights into the dependences of component permeances Π _i in microporous membranes on the operating conditions (upstream partial pressures, temperature, and feed composition). It is argued that the permeances Π _i for unary systems and mixtures need to be compared on the basis of the adsorption potential πA/RT, a convenient and practical proxy for the spreading pressure π that is calculable using the ideal adsorbed solution theory for mixture adsorption equilibrium. The use of πA/RT as a yardstick serves to elucidate and rationalize a wide variety of published experimental Π _i data on unary and mixture permeances in microporous membranes. For cage-type host structures such as SAPO-34, DDR, and ZIF-8, the Π _i values are uniquely dictated by the magnitude of πA/RT, irrespective of the partner species in the mixture. For MFI membranes, the tardier species slows down the more mobile partners due to correlated molecular motion within the channels; the degree of correlation is also a function of πA/RT.

SUBMITTER: Krishna R 

PROVIDER: S-EPMC6545543 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature