Gas Separation through Conductive Polymer Membranes. 2. Polyaniline Membranes with High Oxygen Selectivity

Gas permeation experiments of O2 and N2 were performed with conducting polyaniline (PANi) composite membranes prepared by using a porous nylon membrane as a support. PANi composite membranes were easily obtained by a novel solvent welding process. Doping, dedoping, and redoping kinetics of PANi composite membranes were studied by calculating the [Cl]/[N] content using elemental analysis. After doping and dedoping processes, the permeability of a dedoped PANi membrane decreased while selectivity slightly increased, probably because of the changes in morphology of PANi. d spacing of the PANi film decreased from 4.89 to 3.67 Å after doping, dedoping, and redoping. As redoping continued, the degree of doping increased while the d spacing decreased, resulting in a dramatic increase in selectivity of a PANi membrane. The highest O2/N2 selectivity and permeability we obtained from PANi redoped for 2 h were 28 and 0.13 barrer, respectively. O2/N2 permeation experiments with different upstream pressure and temperature were carried out to study the permeation behavior of a PANi membrane.