Removal and recovery of aqueous U(VI) by heterogeneous photocatalysis: Progress and challenges

With the rapidly expanding implementations of nuclear power technology, the contamination of the aquatic environment by uranium is a rising environmental problem. Photocatalytic reduction of hexavalent uranium (U(VI)) is a plausible solution to the aqueous uranium contamination, which has generated increasing research interest in the recent decade. Therefore, a systematic assessment highlighting the important direction for future studies is in need. We herein present a critical review to address the following two aspects: (1) the progress and current understandings of photocatalytic U(VI) removal technology, including various applied catalysts, current understanding of the kinetics and mechanisms, the effects of key operation parameters, and the effects of co-existing water constituents; (2) key knowledge gaps that need future research efforts in this field.