Chitosan/TiO2 nanocomposite pervaporation membranes for ethanol dehydration

Novel chitosan/titanium dioxide (CS/TiO2) nanocomposite membranes were prepared using tetrabutyl titanate (TBT) as precursor and acetyl acetone as chelating agent by in situ sol–gel process, and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetry (TG). The characterization results demonstrated that nano-sized TiO2 particles dispersed homogeneously within the CS matrix, which could be assigned to the hydrogen and titanoxane bonds formed between CS and TiO2. Moreover, the pervaporation performance of these membranes was investigated using the separation of ethanol–water mixture as model system. Compared with CS/TiO2 hybrid membranes prepared by blending method, most of CS/TiO2 nanocomposite membranes prepared by in situ sol–gel process exhibited higher permeation flux and separation factor under the identical conditions. Among all the prepared membranes, CS/TiO2 nanocomposite membrane containing 6 wt% TiO2 exhibited the best pervaporation performance, whose averaged permeation flux and separation factor were 0.340 kg m−2 h−1 and 196 for 90 wt% aqueous solution of ethanol at 80 °C, respectively.