Enhanced photocatalytic reduction activity of uranium(<scp>vi</scp>) 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.