Visible-Light-Driven AO7 Photocatalytic Degradation and Toxicity Removal at Bi-Doped SrTiO(3)

In this study, Bi-doped SrTiO(3) perovskites (Sr(1−x)Bi(x)TiO(3), x = 0, 0.03, 0.05, 0.07 and 0.1) were synthesized using the solid-state method, characterized, and tested as photocatalysts in the degradation of the azo dye acid orange 7 (AO7) under visible light. The perovskites were successfully synthesized, and XRD data showed a predominant, well-crystallized phase, belonging to the cubic perovskite symmetry. For the doped samples, a minority phase, identified as bismuth titanate, was detected. All doped samples exhibited improved photocatalytic activity under visible light, on the degradation of AO7 (10 mg L(−1)), when compared with the undoped SrTiO(3), with an increase in relative Abs(484 nm) decay from 3.7% to ≥67.8% after 1 h, for a powder suspension of 0.2 g L(−1). The best photocatalytic activity was exhibited by the Sr(0.95)Bi(0.05)TiO(3) perovskite. Reusability studies showed no significant loss in photocatalytic activity under visible light. The final solutions showed no toxicity towards D. magna, proving the efficiency of Sr(0.95)Bi(0.05)TiO(3) as a visible-light-driven photocatalyst to degrade both the AO7 dye as well as its toxic by-products. A degradation mechanism is proposed.