Pervaporation dehydration of isopropanol using blend membranes of chitosan and hydroxypropyl cellulose

摘要

Chitosan and hydroxypropyl cellulose (CS-HPC) blend membranes prepared by solution casting method, followed by crosslinking with urea-formaldehyde-sulfuric acid mixture, were tested for the pervaporation (PV) dehydration of isopropanol. Membranes were characterized by FTIR and XRD to assess intermolecular interactions and observe the effects of blending on crystallinity. Pervaporation dehydration using crosslinked CS-HPC blend membranes were studied at varying feed water compositions, membrane thickness and temperature. It was found that blend membrane containing 20 wt.% HPC (CS-HPC-20) gave a high selectivity of 11,241 for 10 wt.% water containing feed mixture. Comparatively, a low selectivity of 488 was observed for plain crosslinked CS membrane for the same feed mixture; this value further decreased with increasing water composition of the feed mixture. Flux of the plain CS membrane increased from 0.074 to 0.246 kg/m~2 h over the studied feed water compositions of 10-30 wt.%. For CS-HPC-20 membrane, fluxes increased from 0.132 to 0.316 kg/m~2 h. The observed flux was higher for CS-HPC blend membranes, but lower for the plain crosslinked CS membrane; nevertheless, selectivity was higher for CS-HPC-10 (i.e., membrane containing 10 wt.% HPC) and CS-HPC-20 blend membranes. At 40 wt.% of HPC, i.e., for CS-HPC-40 membrane, flux was increased from 0.226 to 0.391 kg/m~2 h, but selectivity decreased from 453 to 80 over the composition range of 10-30 wt.% water in the feed. With increasing temperature, flux increased considerably, but selectivity decreased. Permeation flux followed the Arrhenius trends over the investigated range of temperature.