The effect of structure on pervaporation of chitosan membrane

The impact of fabrication conditions on the chitosan (CS) membrane structur e and its pervaporation (PV) performance are studied in this paper. Chitosa n homogenous membranes were fabricated by casting a chitosan/acetic acid so lution, then heating it at various temperatures and for different periods o f post-hearing time, followed by chemically cross-linking with H2SO4. The P V separation tests using the resulting membranes demonstrate that the chito san membranes are capable of separating water-ethanol mixtures. The optimiz ed 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 f actor to PV performance of separating water-ethanol, It was observed in ort hogonal tests that the effect of membrane preparation temperature on the se paration factor was significant. Further studies show that the separation f actor is the highest when the heating temperature is 343 K. The results of differential scanning calorimetric (DSC) and X-ray diffraction analyses sug gest that the chitosan membranes contain two major different types of cryst als. It has been observed that the crystal degree of the chitosan membrane changes with varying heating membrane preparation temperature, i.e. the fra ctions of two types of crystal change as temperature changes. The present w ork clearly correlates the PV separation performance of water-ethanol by us ing the chitosan membrane with the crystal property resulting from the prep aration temperature. (C)2000 Elsevier Science B.V. All rights reserved.