Synergistic adsorption and photocatalysis reduction of uranium by UiO-66 (Ce)-CdS/PEI-modified chitosan composite sponge

Uranium is a critical element of the nuclear industry, and while extracting it from seawater is considered the most promising way to meet the growing demand for uranium, there are still some problems that still need to be solved. This work designed a UiO-66(Ce)-CdS/PEI-modified chitosan composite sponge (USPS) with an adsorption-photocatalytic synergistic effect to extract uranium efficiently. On the one hand, the drawback that the powder material is difficult to be recycled is solved. On the other hand, the uranium extraction capacity of the substrate sponge is improved. Compared with the unmodified PCS sponge, the uranium extraction capacity of the USPS-4 composite sponge is 1.63 fold higher than that of the PCS sponge. In addition, the USPS-4 composite sponge exhibits excellent selectivity and regenerability. The mechanism of uranium extraction can be summarized as the coordination chelation of uranium with active functional groups in the adsorption process and the reduction of hexavalent uranium by photogenerated electrons in the photocatalytic process. This study provides a new strategy for designing and preparing a novel material with high uranium extraction performance, easy separation, and recovery.