Preparation of polyvinyl alcohol-silica hybrid heterogeneous anion-exchange membranes by sol-gel method and their characterization

Polyvinyl alcohol-silica hybrid heterogeneous anion-exchange membranes were prepared by sol-gel method by dispersing the anion-exchange resin in the gel formed by acid/base hydrolysis of tetraethylorthosilicate in polyvinyl alcohol solution. The effect of acid and base-catalyzed hydrolysis on membrane preparation and extent of resin loading was studied. Various membranes were prepared with 60% (w/w) anion-exchange resin (Indoin FFIP) loaded with different extents of silica. Membrane potential and membrane resistance measurements have been carried out with different counter-ion to investigate the relationship between ionic migration and silica content in the membrane forming material. Counter-ion transport number and permselectivity, of these membranes were found to very due to the silica content and nature of counter-ion. Data indicates that, with increase in compactness of the membranes, its ability to discriminate between counter-ions also increases. Decrease in relative transport of bulkier ions are useful, especially, desirable for selective removal of these type of ions or membrane based electrochemical sensors. (C) 2004 Published by Elsevier B.V.