The effect of structure on pervaporation of chitosan membrane

The impact of fabrication conditions on the chitosan (CS) membrane structure and its pervaporation (PV) performance are studied in this paper. Chitosan homogenous membranes were fabricated by casting a chitosan/acetic acid solution, then heating it at various temperatures and for different periods of post-hearing time, followed by chemically cross-linking with H2SO4. The PV separation tests using the resulting membranes demonstrate that the chitosan membranes are capable of separating water-ethanol mixtures. The optimized conditions for chemical cross-linking of membranes were found to be 0.5 M of the cross-linking reagent (H2SO4) and 10 min reaction time at ambient temperature. The preparation temperature of chitosan membranes is the key factor to PV performance of separating water-ethanol, It was observed in orthogonal tests that the effect of membrane preparation temperature on the separation factor was significant. Further studies show that the separation factor is the highest when the heating temperature is 343 K. The results of differential scanning calorimetric (DSC) and X-ray diffraction analyses suggest that the chitosan membranes contain two major different types of crystals. It has been observed that the crystal degree of the chitosan membrane changes with varying heating membrane preparation temperature, i.e. the fractions of two types of crystal change as temperature changes. The present work clearly correlates the PV separation performance of water-ethanol by using the chitosan membrane with the crystal property resulting from the preparation temperature. (C)2000 Elsevier Science B.V. All rights reserved.