Dehydration of THF-water mixtures using zeolite-incorporated polymeric membranes

Using a solution technique, polymeric composite membranes were prepared by the incorporation of NaY zeolite into chitosan. The resulting membranes were tested for pervaporation separation of water-tetrahydrofuran mixtures in a temperature range of 30-50°C. The effect of membrane swelling on the separation performance was studied by varying the water composition in the feed from 5 to 30 mass %. Pervaporation data demonstrated that both flux and selectivity increased simultaneously with increasing zeolite content in the membrane. This was explained on the basis of enhancement of hydrophilicity, selective adsorption, and establishment of molecular sieving action. It was found that both total flux and flux of water are close to each other, suggesting that the developed membranes are highly selective toward water. The membrane containing the highest loading of zeolite exhibited the highest separation selectivity of 2140 with a substantial water flux of 16.88 x 10⁻² kg/(m² h) at 30°C for 5 mass % of water in the feed. From the temperature dependency of diffusion and permeation data, the Arrhenius activation parameters were estimated. A significant difference was noticed between Epw and EpTHF, EDw and EDTHF values, signifying that membranes developed with higher loading of zeolite exhibited remarkable separation selectivity toward water. The Ep and ED values ranged between 11.69 and 21.23, and 11.21 and 20.72 kJ/mol, respectively. All the membranes exhibited positive ΔHs values, suggesting that the heat of sorption is still dominated by Henry's mode of sorption.