A reductive strategy with ultrahigh selectivity for sequential recovery of uranium from radioactive wastewater

Uranium is valuable metal, and it is of great significance to develop a simultaneous separation process of uranium and cesium from radioactive wastewater. Herein, a process was designed to separate sequentially uranium and cesium from wastewater. By comparing the limiting ability of OH- and CO32- to Co2+, Cd2+, and Sr2+ ions, it was found that CO32- could effectively limit the above ions to the solid phase. The result of X-ray photoelectron spectroscopy (XPS) and species analysis revealed that the restriction was achieved through complexation. Through this property, more than 99.9 % of cobalt and cadmium were limited in the solid phase, and U-Cs co-separation was realized. Furthermore, the results of cyclic voltammetry and XPS indicated that U(VI) could be reduced in the liquid phase, but Cs(I) could not, which was the basis for uranium and cesium separation. And more than 99.5 % of uranium was separated from cesium by the electrochemical separation process. Simultaneously, effective separation of uranium and cesium under different pHs has been achieved via selective uranium leaching using carbonate. The co-separation combined with electrochemical separation realized the recovery of pure uranium products, indicating a large potential for realizing uranium resources in wastewater.