Plasma-grafted PVDF polymers as anion exchange membranes for the electrotransport of Cr(Ⅵ)

摘要

Grafting of aminosiloxane groups on PVDF supports was performed in a low-frequency plasma deposition process using a tetramethylsilane/ammoniac mixture. The morphology and thickness of plasma-grafted PVDF membranes were characterized by SEM observations; their chemical structure was determined by FTIR analysis, XPS analysis, and contact angle measurements. The membranes anion-exchange capacity for the transport of Cr(Ⅵ) was investigated by electro-electrodialysis using a three compartments Kel'F cell. We are able to correlate the plasma grafting parameters with the structure and the electrotransport performances of the synthesized membranes. Starting from 0.10 for the virgin PVDF films, the best Cr(Ⅵ) transport number (0.155) is obtained for membranes both rich in substituted amine functions and hydrophobic enough synthesized from an equimolar tetramethylsilane/ammoniac plasma monomers mixture.