Copper-doped nano-cubic SrTiO₃ photocatalyst efficiently removes U(VI) from uranium mine pit water

The Cu-doped SrTiO₃ photocatalysts were prepared by hydrothermal and calcination methods for photocatalytic reduction of U(VI) in mine pit water. Specifically, Cu doping decreases the bandgap of the catalyst, broadening the light absorption spectrum and accelerating photo-induced charge carrier separation. Consequently, these modifications significantly enhance the performance of photocatalytic uranium reduction. With methanol as a hole scavenger, the removal rate of U(VI) in 100 mg/L simulated pit water was 89.4%. When there is no hole scavenger, the photocatalyst still achieves a 71.3% uranium removal rate in actual mine pit water (25 mg/L). In addition, the photocatalyst has a certain degradation effect on the natural organic matter (NOM) in the actual mine water. XPS analysis reveals that uranium reduction involves Ti(III)/Ti(IV) and Cu(I)/Cu(II) redox processes. The redox processes of these metals may enhance the reducing properties of photocatalysts. This study presents a new method for large-scale mine pit water treatment via Cu-doped SrTiO₃ photocatalysts.