Enhanced photocatalytic degradation of metronidazole by TiO2 decorated on magnetic reduced graphene oxide: Characterization, optimization and reaction mechanism studies

In this work, the TiO2 decorated magnetic reduced graphene oxide was fabricated by the hydrothermal method. The characterization of prepared composite was studied by XRD, FT-IR, SEM, EDX, BET, and TGA techniques. Both the magnetization of TiO2 by Fe3O4 nanoparticles and then its decorating on rGO surface were confirmed using characterization tests. The photocatalytic efficacy of the provided samples was defined via the degradation of metronidazole (MNZ) under visible light irradiation. The operational parameters' effect, including pH, catalyst dosage, initial MNZ concentration, rGO, and TiO2, was evaluated. The results indicated that the maximum degradation rate of MNZ (0.0092 min−1) was obtained for 0.75 g composite containing 4% rGO and 5% TiO2 at pH = 5 and MNZ concentration of 20 mg/L. MNZ and TOC were eliminated completely at optimum operational conditions within 120 and 250 min reaction times, respectively. The quenching test revealed that O2•- acted as dominant radical in the degradation process. [Display omitted] •TiO2 nanoparticles are decorated on magnetic reduced graphene oxide.•rGO improved the photocatalytic efficiency of TiO2 by hindering the electron/hole recombination.•O2•- acted as dominant radical in the degradation process.•4% rGO and 5% TiO2 content provide maximum MNZ degradation.