Synthesis and characterization of GTMAC grafted chitosan membranes for the dehydration of low water content isopropanol by pervaporation

Abstract

Glycidyltrimethylammonium chloride (GTMAC) grafted chitosan (CS) membranes were prepared by the solution casting technique. The chemical composition and morphological characteristics of the prepared GTMAC/CS membranes were investigated by various techniques such as Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The effects of grafting and feed composition on pervaporation performance of the membranes were systematically studied. The membrane containing 40 mass% of GTMAC exhibited the highest separation selectivity of 2133 with a flux of 6.91×10−2kg/m2h at 30°C for 10 mass% of water in the feed. The total flux and flux of water are almost overlapping each other, manifesting that these membranes could be used effectively to break the azeotropic point of water–isopropanol mixture. From the temperature dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The activation energy values obtained for water permeation (Epw) are significantly lower than those of isopropanol permeation (EpIPA), suggesting that the grafted membranes developed here have higher separation ability for water-isopropanol system. The positive heat of sorption (ΔHs) values was obtained for all the grafted membranes, suggesting that the Henry's mode of sorption is predominant.