Abstract
Simultaneous photoassisted oxidation of organic dyes (methylene blue (MB), crystal violet (CV)) and reduction of metal ions (Ag(I), Cu(II)) were studied using new synthesized hierarchical structures of anatase/rutile TiO2 microspheres-reduced graphene oxide (TiO2-rGO) nanocomposites. Interestingly, rutile/anatase phase transformation was observed upon changing the graphene oxide content. An increasing of the anatase/rutile ratio upon increasing the graphene oxide content was observed. Additionally, the synthesized nanocomposites show enhanced photocatalytic activity either for the reduction of heavy metal ions or for the degradation of the dyes compared to pristine TiO2 nanoparticles. A highest activity has been achieved using the nanocomposite containing 62% anatase and 38% rutile. This enhancement in the photocatalytic activity can be attributed to the synergetic effect between anatase and rutile in the synthesized TiO2 microspheres composites. Furthermore, The study of the effect of various concentrations of metal ions shows that increasing the metal ions concentration highly promoted the photocatalytic degradation of the organic dyes. A complete decoloration of both dyes has been observed within very short time. Furthermore, enhancement of the photocatalytic reduction of the metal ions was achieved by increasing the dye concentration. Therefore, an obvious synergistic effect was observed leading to the enhancement of both the photocatalytic and reduction. The results show a cost effective method for a simultaneous removal of organic and inorganic pollutants from wastewater.