Synthesis and characterization of PVDF supported silica immobilized phosphotungstic acid (Si-PWA/PVDF) ion exchange membrane

• Phosphotungstic acid based ion exchange membrane was synthesized.
• XRD patterns indicated crystalline phase in membrane.
• Transport number for cation was 0.91.
• Ion exchange capacity of membrane was 0.82 meq/g.

An ion exchange membrane was synthesized by impregnating sub-micron sized silica-immobilized phosphotungstic acid (Si-PWA) particles on a porous (poly vinylidene fluoride) (PVDF) film. Surface morphology, crystalline nature and thermal stability of the membrane were studied. The membrane was found to have a defect free surface, which contained both crystalline and amorphous phases and was stable up to 350 °C. Electrochemical properties (transport number) of membranes of two different PWA/TEOS (tetraethoxyorthosilicate) ratios were compared and the one with a higher ratio gave better properties. Ion exchange capacity (IEC) of 0.82 meq/g and counter-ion transport number of 0.91 indicated good electrochemical properties of the membrane synthesized with sol of PWA/TEOS ratio of 1.5.