Pervaporative separation of ethanol/water azeotrope using a novel chitosan-impregnated bacterial cellulose membrane and chitosan-poly(vinyl alcohol) blends

The pervaporative (PV) performance with respect to the separation of ethanol/water (EtOH/H2O) azeotrope was assessed for a bacterial cellulose membrane (BCM) impregnated with chitosan (CTSN), designated as CTSN-BCM. The PV potential of CTSN-BCM was compared with that of parent polymers and also with the blends of CTSN with poly(vinyl alcohol) (PVA). The blends and CTSN-BCM were characterized using spectroscopic and thermoanalytical techniques, and also tested for their mechanical strength and sorption of EtOH/H2O mixtures. While PVA and the blends tend to dissolve at higher concentration of water, CTSN-BCM was found to be intact over the entire composition range. When evaluated against pervaporation of 95:5 w/w EtOH/H2O azeotrope at 24 +/- 1 degrees C; CTSN-PVA (1:1) blend showed comparatively higher selectivity (22.0) but a poorer flux ( 1.7 kg mu m m(-2) h(-1)). The flux was significantly higher (42.8 kg mu m m(-2) h(-1)) in CTSN-BCM and selectivity (similar to 10) was at par with PVA. The temperature dependence of selectivity and flux through CTSN-BCM was also investigated. Substantially high pervaporative separation index (PSI) of the order of 350 kg mu m m(-2) c h(-1) and low energy of activation of 10kJ/mol is indicative of the potential of CTSN-BCM in the pervaporative separation of EtOH/H2O azeotrope. (c) 2004 Published by Elsevier B.V.