Comparison study on photocatalytic oxidation of pharmaceuticals by TiO-Fe and TiO-reduced graphene oxide nanocomposites immobilized on optical fibers.

Incorporating reduced graphene oxide (rGO) or Fe ions in TiO photocatalyst could enhance photocatalytic degradation of organic contaminants in aqueous solutions. This study characterized the photocatalytic activities of TiO-Fe and TiO-rGO nanocomposites immobilized on optical fibers synthesized by polymer assisted hydrothermal deposition method. The photocatalysts presented a mixture phase of anatase and rutile in the TiO-rGO and TiO-Fe nanocomposites. Doping Fe into TiO particles (2.40eV) could reduce more band gap energy than incorporating rGO (2.85eV), thereby enhancing utilization efficiency of visible light. Incorporating Fe and rGO in TiO decreased significantly the intensity of TiO photoluminescence signals and enhanced the separation rate of photo-induced charge carriers. Photocatalytic performance of the synthesized nanocomposites was measured by the degradation of three pharmaceuticals under UV and visible light irradiation, including carbamazepine, ibuprofen, and sulfamethoxazole. TiO-rGO exhibited higher photocatalytic activity for the degradation of pharmaceuticals under UV irradiation, while TiO-Fe demonstrated more suitable for visible light oxidation. The results suggested that the enhanced photocatalytic performance of TiO-rGO could be attributed to reduced recombination rate of photoexcited electrons-hole pairs, but for TiO-Fe nanocomposite, narrower band gap would contribute to increased photocatalytic activity.