Enhanced Photocatalytic Removal of Uranium(VI) from Aqueous Solution by Magnetic TiO/FeO and Its Graphene Composite.

The separation and recovery of uranium from radioactive wastewater is important from the standpoints of environmental protection and uranium reuse. In the present work, magnetically collectable TiO/FeO and its graphene composites were fabricated and utilized for the photocatalytical removal of U(VI) from aqueous solutions. It was found that, under ultraviolet (UV) irradiation, the photoreactivity of TiO/FeO for the reduction of U(VI) was 19.3 times higher than that of pure TiO, which is strongly correlated with the Fe and additional Fe(II) generated from the reduction of FeO by TiO photoelectrons. The effects of initial uranium concentration, solution pH, ionic strength, the composition of wastewater, and organic pollutants on the U(VI) removal by TiO/FeO were systematically investigated. The results demonstrated its excellent performance in the cleanup of uranium contamination. As graphene can efficiently attract the TiO photoelectrons and thus decrease their transfer to FeO, the photodissolution of FeO in the TiO/graphene/FeO composite can be largely alleviated compared to that of the TiO/FeO, rendering this ternary composite a much higher stability. In addition, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), and X-ray photoelectron spectroscopy (XPS) were used to explore the reaction mechanisms.