| Gas transport properties in polyaniline membranes and separation of water/ethanol mixtures by pervaporation using polymer membranes were investigated.; In part A, the transport properties of He, H{dollar}sb2{dollar}, CO{dollar}sb2{dollar}, O{dollar}sb2{dollar}, N{dollar}sb2{dollar}, and CH{dollar}sb4{dollar} gases in solvent cast, HCl doped, and undoped polyaniline (PANi) membranes were determined from 19{dollar}spcirc{dollar}C to 60{dollar}spcirc{dollar}C. An excellent correlation was found between the diffusion coefficients and the molecular diameters of gases. The solubility coefficients of gases were found to correlate with their boiling points or critical temperatures. The high solubility CO{dollar}sb2{dollar} in the polymer dominated the separation factors for CO{dollar}sb2{dollar}/N{dollar}sb2{dollar} and CO{dollar}sb2{dollar}/CH{dollar}sb4{dollar} pairs. These correlations enable us to predict the permeability, diffusion, and solubility coefficients of other gases. After the doping-undoping process, the fluxes of gases with kinetic diameters smaller than 3.5 A increased but those of larger gases decreased. This results in a higher separation factor for a gas pair involving a small gas molecule and a larger one.; The solubilities of polymethoxyaniline (PMANi) and polyethoxyaniline (PEANi) in organic solvents are improved, with respect to PANi. Gas transport properties through the two membranes were studied in order to determine the effect of substitutents. When compared with polyaniline, the gas permeability increases with the size of substituent due to the increases in the diffusivities while the selectivities either remain the same or increase for some gas pairs.; In part B, the permeation rates and the separation of water/ethanol mixtures through membranes by pervaporation (PV) were studied. Since the structure characteristic of a membrane was the most important factor in the performance of the process, we investigated the PV separation of the above mixtures through three different membranes, polyaniline (PANi), an interpolymer complex of poly(acrylic acid) and poly(1-vinyl-2-pyrrolidone) (PAA-PVP), and chitosan. It was observed that the solubility selectivities ({dollar}alphasb{lcub}rm S{rcub}{dollar}) in chitosan dominated the separation efficiencies due to the preferential and larger water absorption in the membrane, but, the diffusion selectivities {dollar}(alphasb{lcub}rm D{rcub}){dollar} of the PAA-PVP complex membrane dominated the separation performance because of the higher permeation rate of water. |
