Advanced reduction of bromate by UV/TiO2-Bi process without external sacrificial agents: Mechanism and applications

Recently, the heterogeneous advanced reduction processes (ARPs) for bromate (BrO 3 - ) degradation have attracted considerable attention due to its stable performance and easy combination with UV disinfection. In this study, a UV/TiO 2 -Bi advanced reduction process (ARP) was established for BrO 3 - removal without adding external sacrificial agents. In the UV/TiO 2 -Bi ARP, Bi nanoparticles (NPs) doped on the TiO 2 acted as hole trapping centers, while TiO 2 NPs were used as reduction centers for the reduction of BrO 3 - , which enhanced the charge carrier separation. The UV/TiO 2 -Bi-1% ARP exhibited the highest BrO 3 - removal rate without the addition of sacrificial agents in the reaction solution compared to UV/TiO 2 ARP and the UV/TiO 2 -Bi ARP at other Bi/Ti ratios. The result of 72% removal of 200 µg/L BrO 3 - at 60 min by 0.2 g/L TiO 2 -Bi-1% in tap water at pH 6.8 and 7.71 mg/L dissolved oxygen (DO) demonstrates the promising potential of the UV/TiO 2 -Bi ARP for the removal of BrO 3 - in practical applications. Compared to the 99.5% removal in deionized (DI) water at 60 min, lower BrO 3 - reduction in tap water was likely attributed to the consumption of photo-generated electrons by NO 3 – and the adsorption of natural organic matter on the surface of TiO 2 -Bi-1% nanocomposites. The study provides not only a novel BrO 3 - removal system with good photo-reduction performance, but also some guidance for the influence of constituents in raw water on the treatment of BrO 3 - .