Pervaporation Properties and Characterization of Poly (vinyl alcohol)/Cellulose Nanocrystal Composite Membranes

Poly(vinyl alcohol) (PVA)/cellulose nanocrystal (NCC) composite membranes were used in the pervaporation separation of water-ethanol feed mixtures, and characterized by Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), differential scanning calorimetric(DSC) and thermogravimetry(TG). Atomic force microscope (AFM) was used to characterize the cellulose nanocrystal. The characterization results demonstrated that NCC displayed slender rods and dispersed homogeneously within the PVA matrix, which could be assigned to the hydrogen bonds formed between PVA and NCC. The DSC and TG analysis demonstrated that the nanocomposite membranes exhibited an increase in melting temperature and higher thermal resistance. With the addition of NCC, the mechanical properties of the nanocomposite membranes were improved. Moreover, the nanocomposite membranes had good pervaporation properties. Among all the prepared membranes, PVA/NCC nanocomposite membrane containing 2% NCC exhibited the best separation factor, whose averaged separation factor was 347 for aqueous solution of ethanol(90%) at 80 degrees C and 24% higher than that of crosslinked PVA membrane, but its permeation flux was 288 g/(m(2).h), 11% lower than crosslinked PVA membrane.