Preparation of organic–inorganic hybrid cation-exchange membranes via blending method and their electrochemical characterization

Organic–inorganic hybrid membranes based on poly(vinylidene fluoride)-SiO2 nanoparticles were prepared by blending method and cation-exchange groups in the membrane matrix were introduced by the reaction of epoxy groups with fuming sulfuric acid at 25 °C. Various membranes were prepared with different content of SiO2 nanoparticles. These membranes were extensively characterized for their surface morphology, thermal stability, water content and surface charge property using SEM, FTIR, TGA, water uptake and ion-exchange capacity measurements. Membrane potential measurements along with membrane surface fixed charge density have been carried out with different counter-ions to investigate the relationship between ionic migration and SiO2 content in the membrane forming material. Membrane conductance performed in NaCl solution was interpreted not only by the counter-ion diffusion coefficient in the membrane phase but also by phenomenology coefficients. It was found that physicochemical and electrochemical properties of these membranes were found to be highly dependent on the SiO2 nanoparticles content in the membrane matrix. Furthermore, membranes with SiO2 nanoparticles in 2.0% weight ratio of PVDF exhibited very good selectivity, water content, ion-exchange capacity and moderate membrane conductivity, which may be used for their application in electro-membrane processes.