Permeation of carbon dioxide through homogeneous and asymmetric polysulfone membranes

To confirm the validity of the working assumption that a thin dense skin layer in an asymmetric membrane can be essentially replaced by a thick homogeneous dense membrane, both homogeneous and asymmetric polysulfone membranes were prepared by solvent casting, and the permeation behavior of carbon dioxide through these two types of membranes was investigated. The pressure dependence of the mean permeability coefficient through an asymmetric polysulfone membrane is apparently very similar to that through a homogeneous dense membrane, following the dual mode mobility model driven by gradients of chemical potential. The dense skin layer in the asymmetric membrane can be simulated approximately by a homogeneous dense membrane from the point of view of gas sorption and diffusion.