Enhanced photocatalytic reduction activity of uranium(VI) from aqueous solution using the Fe2O3-graphene oxide nanocomposite

Photocatalytic technologies are a potential solution for remediation of radioactive wastewater, including the reduction of radioactive hexavalent uranium, which is commonly found in wastewater from the nuclear industry. In this study, Fe2O3-graphene oxide composites were synthesized by an easy and scalable impregnation method as a catalyst for the reduction of U(VI). X-ray photoelectron spectroscopy analysis and high-resolution transmission electron microscopy images of this composite clearly showed that the Fe2O3 nanoparticles exist in the layered structure of graphene oxide. The photocatalytic activity of the Fe2O3-graphene oxide composite was evaluated by the reduction of U(VI) to U(IV) in aqueous solution under visible light. The results showed that the photocatalytic process of the Fe2O3-graphene oxide composite was always faster than that of the Fe2O3 nanoparticles. Moreover, the experimental kinetic data for the catalytic process followed a pseudo-first-order model. The stability of the Fe2O3-graphene oxide composites was studied over successive experiments, with the photocatalytic reduction efficiency of U(VI) decreasing to 76.0% after four cycles. Based on these experimental results, the enhanced photocatalytic activity and stability of Fe2O3-graphene oxide composites can be attributed to the improved adsorption properties of U(VI) at GO and the electron transfer from iron oxide to GO.