The photocatalytic application of Gd(OH)3/Cd0.8Zn0.2S nanocomposites in U(VI) reduction

Photoreduction of soluble U(VI) to insoluble U(IV) is an effective method for removing uranium from radioactive wastewater, but the available catalysts are very limited. In this study, a novel photocatalyst Gd(OH)3/Cd0.8Zn0.2S was synthesized for the photocatalytic reduction of U(VI). The optimal reduction of U(VI) in Gd(OH)3/Cd0.8Zn0.2S was up to 95.2%, which was 4.1 and 1.7 times that of Gd(OH)3 and Cd0.8Zn0.2S, respectively. Various methods characterized the composite, and the analysis showed that the outstanding photocatalytic property was mainly ascribed to its good photo-adsorption capacity and narrow band gap. Meanwhile, the heterojunction between Gd(OH)3 and Cd0.8Zn0.2S promoted the separation and transfer of the photogenerated carriers. After five cycles, the removal efficiency remained above 90%, indicating that the composite had good structural stability and reusability. In addition, a possible mechanism for U(VI) photocatalytic reduction was proposed. This study is significant in designing potentially efficient photocatalysts to eliminate U(VI) contaminants.