Incorporation of particulate fillers in a membrane matrix has been proven effective in improving the separation performance of the membrane. This study explored the possibility of casting fillers embedded membranes with the assistance of alternating electric field to further improve the membrane performance in gas separation. Composite membranes with varying contents of multi-walled carbon nanotubes (MWCNTs) dispersed in polystyrene (PS) were prepared. In order to align the MWCNTs in the membrane

an alternating electric field of 2000 V·cm-1

1 Hz was vertically applied on the pre-membrane solution until the solvent was evaporated completely. Electro-casting achieved not only vertical alignment but also more uniform dispersion of MWCNTs in the membrane matrix. The electro-cast composite membranes showed higher permeability of both carbon dioxide and methane

but the increment of the former was higher than the latter

resulting in improved selectivity of the membrane.