Sunlight Assisted Photodecolorization of Methylene Blue Catalyzed by H3PW12O40 Grafting on APTMS-Graphene Oxide

Surface of graphene oxide was modified by grafting 3-aminopropyl- triethoxysilane to have the positive charge, and thus, to provide sites for the immobilization of H3PW12O40. This modified-nanosized material (PW12-APTMS@GO) was characterized by FTIR, XRD, BET, SEM and TEM. XRD shows that the structure of graphene remains intact after two steps of modifications, while spectral techniques show the successful grafting of PW12 on the graphene layers. PW12-APTMS@GO was used as a catalyst in the photodecolorization process of methylene blue dye in aqueous solution under sunlight radiation. The optimum values of the experimental parameters affecting the degradation efficiency were obtained as: 0.015 g L^−1 of the photocatalyst, 30 ppm dye concentration and pH 3.0. It was found that the catalyst exhibits a significantly high catalytic stability, and the activity loss is negligible after five methylene blue degradation cycles.