Blended chitosan and poly (vinyl alcohol) membranes for the prevaporation of methanol and methyl tert-butyl ether

摘要

In this research project, blended chitosan/poly(vinyl alcohol) (PVA) membranesudwere produced by mixing PVA and chitosan solutions. Chitosan (CS) was firstuddissolved in acetic acid aqueous solution before PVA solution was added. The mixtureudwas then cured at room temperature. The modified composite membrane was preparedudby coating the mixture of chitosan and PVA solution onto the porous polysulfoneudmembrane by the solution casting technique. The porous polysulfone substrate wasudprepared via phase inversion process from a casting solution containing 12 wt%udpolysulfone, 11 wt% polyethylene glycol and 77 wt% N,N- dimethylacetamide. Theudweight percent of chitosan in the membrane was varied from 20 wt. % to 100 wt. %udwhile the membrane thickness was in the range of 15-30 μm. The unmodified andudmodified composite membranes with PVA were used in pervaporation separation ofudmethanol/methyl-tert-butyl ether (MTBE) mixture. The swelling degree and the totaludflux increased with increasing chitosan content in the membranes. 30 wt. % of methanolud(MeOH) in feed was chose since it gave the optimal overall pervaporation characteristicsudin terms of flux and separation factor. The membrane containing chitosan 20 wt. % toud40 wt. % performed the best. At operating temperature of 50 oC for 20 wt % to 40 wt %udof chitosan, the fluxes obtained are at 52.28 g/m2.hr and 66.92 g/m2.hr with theudseparation factors of 81.00 and 53.22 respectively. The effect of temperature on fluxudfollowed the Arrhenius relationship. The membrane showed excellent performance forudseparation of MeOH/MTBE mixture when the quantity of MeOH in feed is small. It is audvery suitable process for the recovery purpose in order to remove excess MeOH in theudMTBE system.