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 °C; CTSN–PVA (1:1) blend showed comparatively higher selectivity (22.0) but a poorer flux (1.7 kg μm m−2 h−1). The flux was significantly higher (42.8 kg μm m−2 h−1) in CTSN–BCM and selectivity (∼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 μm m−2 h−1 and low energy of activation of 10 kJ/mol is indicative of the potential of CTSN–BCM in the pervaporative separation of EtOH/H2O azeotrope.