Preparation of ceramic-supported poly(vinyl alcohol)-chitosan composite membranes and their applications in pervaporation dehydration of organic/water mixtures

Ceramic-supported poly(vinyl alcohol)-chitosan composite membranes were prepared for pervaporation dehydration purpose. The microstructure, physicochemical properties and surface hydrophilicity of the composite membranes were systematically investigated. The composite membranes have been cross-linked successfully and the surface hydrophilicity decreased with the increase of chitosan content. Pervaporation dehydration of four organic/water mixtures was carried out to study the membrane performance. The pore size of ceramic support influenced the performance of the composite membrane greatly, and the ceramic membrane with the pore size of 0.2 μm is proper for the use as the support. It was found that chitosan played an important role in increasing the membrane permeation flux. When the chitosan content is 60 wt%, the composite membrane exhibited high performance. In the dehydration of alcohol/water mixtures, the permeation flux increased without a decrease in separation factor. This abnormal trend between flux and separation factor suggested that the non-deformable ceramic support had a restricted swelling effect on the composite membrane. In the dehydration of ester/water mixtures, the membrane exhibited excellent pervaporation performance, especially in the dehydration of ethyl acetate/water mixture at 3.5 wt% water in feed with a flux of 1250 gm^-2 h^-1 and a separation factor larger than 10,000.