Photocatalytic degradation of oily wastewater over ZnO‐CuO/rGO photocatalyst under visible light

Abstract Metal oxide composites integrating with carbon materials have attracted a great deal of attention as the potential photocatalysts for environmental treatment. The ZnO‐CuO composites intergrated with reduced graphene oxide (rGO) were successfully prepared via co‐precipitation method. The crystalline structure of the ZnO‐CuO/rGO ternary composites was examined by the X‐ray diffraction analysis. Field emission scanning electron microscopy analysis shows the distribution of metal oxides onto the plate‐like graphene. The calculated band gap values of the ZnO nanoparticles (3.16 eV) were decreased to 2.62 eV in the prepared (ZnO/CuO)/rGO ternary composites. In this work, the photocatalytic activity of the ZnO‐CuO/rGO with 15 % rGO photocatalyst was evaluated for the chemical oxygen demand (COD) of oily wastewater treatment process, which showed COD removal reaching 95 % after 6 h exposure to visible light irradiation. Moreover, the recycle and recovery test revealed the relatively good stability and repetitive use of ZnO‐CuO/rGO for high COD removal of oily wastewater.