Photocatalytic reduction of selenium ions using different TiO2 photocatalysts

Comparative performance studies between different photocatalysts for reduction reactions are scarce. Here, Millennium PC500 and PC50 photoreactivities were investigated for selenite (Se(IV)) and selenate (Se(VI)) reduction to their elemental form (Se(0)) and compared with that of Degussa P25 TiO2. Millennium PC500, with the highest surface area demonstrated the fastest photoreduction of Se(IV) and Se(VI), compared to P25 and Millennium PC50. Millennium PC50 and P25, which have comparable surface areas, showed similar photoreactivities. UV–Vis reflectance measurements and XRD characterisation revealed that the Se(0) deposits underwent phase transformation from amorphous to stable crystalline Se(0) during the drying and ageing process. Overall, the Millennium PCs appear to be promising photocatalysts for the photoreduction process.