Characterization of protonated and sulfonated vermiculite nanofillers for hybrid polymer membranes

Protonated and sulfonated clay minerals are promising nanofillers for hybrid nanocomposite membranes in order to increase their conductivity. The natural clay mineral vermiculite (VER) was protonated using sulfuric acid at varying concentrations of 0.1 M, 0.5 M, and 2 M. Based on XRD and FTIR analyses, the sample treated with 0.5M concentrated acid was selected as suitable material for further sulfonation, which was grafted by a two-step method performed by (3-mercaptopropyl)trimethoxysilane (3-MPTMS) followed by oxidation with H 2 O 2 . Structure and morphology of prepared samples was investigated by XRD, FTIR and SEM with EDAX analysis confirming successful attachment of sulfonic acid (–SO 3 H) groups to the vermiculite structure.