Synthesis, characterization and pervaporation performance of chitosan-g-polyaniline membranes for the dehydration of isopropanol

Chitosan was grafted with polyaniline through oxidative-radical copolymerization using ammonium persulfate as an initiator. The graft material was used to prepare a series of membranes by the variation of aniline ratio. These membranes were characterized by Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The resulting membranes were tested for their ability to separate water-isopropanol mixtures by pervaporation in the temperature range of 30-50 degrees C. The membrane containing 1:3 grafting ratio exhibited the highest separation selectivity of 2092 with a flux of 1.19 x 10(-2) kg/m(2) h at 30 degrees C for 10 mass% of water in the feed. The total flux and the flux of water are close to each other particularly for the grafted membranes, signifying that these could be used to break the azeotropic point of water-isopropanol mixtures. From the temperature dependency of diffusion and permeation values, the Arrhenius activation parameters were estimated and discussed in terms of membranes efficiency. All the membranes exhibited positive heat of sorption (Delta H-s), giving endothermic contribution. (C) 2010 Elsevier B.V. All rights reserved.