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.