Pervaporation Separation of Water-Ethanol Mixtures Using Organic-Inorganic Nanocomposite Membranes

Nanocomposite membranes (NCMs) of chitosan were prepared by incorporating Preyssler type heteropolyacid, namely, H(14)[NaP(5)W(30)O(110)], nanopartides by solution casting and the solvent evaporation method. The nanoparticles as well as the membranes were characterized by a variety of physicochemical techniques. The membranes were employed in pervaporation separation of water-ethanol mixtures at varying feedwater compositions and temperatures. The filler nanoparticles (58 nm size), also functioning as cross-linking agents, are responsible for increasing the thermal stability and mechanical strength of the NCMs over that of the nascent chitosan membrane. Furthermore, a dramatic increase of separation factor of 35 991 for NCMs from a base value of 96 for nascent chitosan membrane demonstrates the influence of filler nanopartides in the matrix due to their favorable interactions with chitosan. Pervaporation performance of the NCMs showed a decrease with increasing feedwater composition and temperature. Diffusion and permeability data of water and ethanol molecules were analyzed by Fick's equation, and temperature dependence was studied through the Arrhenius relationship. Pervaporation data were analyzed on the basis of sorption-diffusion model. The Flory-Huggins theory was used to understand sorption phenomenon and to estimate thermodynamic interaction parameters.