Enhanced photocatalytic reduction activity of uranium(vi) from aqueous solution using the FeO-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, FeO-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 FeO nanoparticles exist in the layered structure of graphene oxide. The photocatalytic activity of the FeO-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 FeO-graphene oxide composite was always faster than that of the FeO nanoparticles. Moreover, the experimental kinetic data for the catalytic process followed a pseudo-first-order model. The stability of the FeO-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 FeO-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.