Pervaporation separation of isopropanol/water mixtures through crosslinked chitosan membranes

Chitosan membrane having 84% degree of deacetylation was crosslinked with toluene-2,4-diisocyanate and tested for the dehydration of isopropanol by the pervaporation method. Pure and crosslinked membranes were characterized by Fourier transform infrared spectroscopy and wide angle X-ray diffraction to study the intermolecular interactions and crystallinity, respectively. Dynamic mechanical thermal analyses were undertaken to assess the thermal and mechanical stabilities of the membranes. Sorption studies were performed in water, isopropanol as well as different composition feed mixtures to understand the polymer-liquid interactions and pervaporation separation mechanism. The membrane appears to have a good potential for breaking the aqueous azeotrope of 87.5 wt.% isopropanol with a high selectivity of 472 and a substantial water flux of 0.39 kg/m2 h 10 μm. The influence of operating parameters such as feed composition, membrane thickness and permeate pressure on membrane performance like flux and selectivity was investigated.