Azeotropic separation of isopropanol-water mixtures by pervaporation using a locally-produced chitosan-based membraneud

摘要

Pervaporation, a membrane process for separation of liquid mixtures has been recognized as an energy efficient alternative to conventional separation methods especially when involves the separation beyond the azeotropic point. In this study, membranes were developed from chitosan. Chitosan were converted from chitin which was ectracted from shrimp shell. The membrane were prepared in the form of homogenous and composite. The performances of the pervaporation membranes were investigated in terms of the permeation flux and separation factor in the isopropanol-water system with emphasis on the breaking of azeotropic composition and the dehydration of high concentration of isopropanol. At ambient temperature, a total flux of 48.8 (g/m2.hr) and a separation factor of 261 were achieved for homogenous membrane at 95 wt% isopropanol in feed. Composite chitosan membrane consisting of a dense skin layer and casted on a porous polysulfone were also developed for dehydration of 95 wt% isopropanol solution. By comparison, composite chitosan showed higher Pervaporation Separation Index (PSI) than homogeneous chitosan at 95 wt% isopropanol in feed solution indicating that composite chitosan membrane has the potential to be commercialized and used as pervaporation membranes for the dehydration of organic mixtures especially for the separation beyond the azeotropic conditions.