Photocatalytic degradation of tetrabromobisphenol A by mesoporous BiOBr: Efficacy, products and pathway

Abstract

Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant around the world. In the present study, for the first time we explored the photocatalytic oxidation of TBBPA by nanoarchitectural BiOBr microspheres. BiOBr photocatalysts were synthesized via solvothermal method with various preparation conditions, and the optimal synthesis condition was determined according to their characterization results and rhodamine B (RhB) removal efficiencies. The prepared optimal BiOBr was mesoporous material of pure tetragonal phase, which removed nearly 100% of RhB from solution after 60min simulated solar light irradiation. The BiOBr was adopted to decompose TBBPA, which was almost totally eliminated after 15min in the UV–vis/BiOBr system. The kinetic analysis indicated that the reaction rate constants were 0.388 and 0.101min−1 for BiOBr and P25 TiO2, respectively, suggesting that BiOBr effectively and kinetically enhanced the decomposition of TBBPA. Eight major reaction products or intermediates were identified by HPLC–MS and HPLC–SIR–MS, and a tentative degradation pathway of TBBPA was proposed. The mechanism originally illustrated that both hydroxylation and debromination played important roles in TBBPA transformation. The exceptional efficiency of mesoporous BiOBr in removing TBBPA represents a promising technique for treatment of TBBPA-containing wastewater or remediation of TBBPA-contaminated environmental matrices.