Photoelectrochemical uranium extraction from uranium mine tailings seepage water

Extracting uranium (U) from mine tailings seepage water can compensate the depletion of conventional U resources. However, current photocatalytic methods have intrinsic obstacles, such as the recombination of charge carriers, and the deactivation of catalysts by extracted U. Here we show that, by applying a small bias potential on the photocatalyst to drive spatial charge-carriers separation, the photoelectrochemical (PEC) method enables much faster U extraction and exceptional stability. In synthetic U-bearing water, the PEC U extraction proceeds via single-step one-electron reduction. Hence stable U(V) is produced from aqueous media under ambient conditions for the first time, implying the potential to facilitate future studies on U(V) chemistry. In real seepage water, the PEC method achieves a capacity of 0.67 gU m-3∙h-1 without further optimization, which is 17 times faster than the photocatalytic method using identical photocatalyst. The PEC U extraction method is therefore of broad research interests.