Preparation and characterisation of polyaniline based membranes for gas separation

Transport rates (permeability) and ideal separation factors for several gas pairs through dense polyaniline membranes are reported. The ideal separati on factors for all gas pairs tested were found to be independent of the pol yaniline membrane thickness whereas the permeability of the single gases sh owed significant variations. Both dedoped and redoped films (film thickness between 9 and 67 mum) were studied. The highest selectivities alpha ((A/B) ) found were 7.6 for the gas pair H-2/CO2 in the case of the dedoped membra ne and 10 for the gas pair H-2/CO2, 6 for O-2/N-2 and 200 for H-2/N-2 in th e case of the redoped membrane. Statistical analysis of a large number of m embranes allowed the critical comparison with results obtained by other gro ups. Comparison with other membrane materials shows that an approximately sixfol d enhancement of the respective separation factors is possible for gas pair s containing hydrogen. Similar separation factors are observed for the gas pairs CO2/O-2, CO2/N-2 and N-2/O-2. Membranes for which Knudsen diffusion was observed exhibited regularly dist ributed micropores (400 nm diameter). (C) 2001 Elsevier Science B.V. All ri ghts reserved.