Photocatalytic Activation of Peroxymonosulfate by Bi₄O₅Br₂ for Highly Efficient Atrazine Degradation

Using bismuth oxyhalides (BiOX) for the peroxymonosulfate (PMS)-assisted visible-light photocatalytic degradation of organic pollutants is a promising and environmentally friendly approach. However, pristine BiOBr suffers from limited visible-light absorption and low charge carrier mobility. In this study, Bi₄O₅Br₂ microspheres were successfully synthesized and employed as a photocatalyst to activate PMS under visible light for the degradation of the herbicide atrazine (ATZ). Experimental results demonstrated that Bi₄O₅Br₂ displayed markedly enhanced photocatalytic activation performance relative to pristine BiOBr, exhibiting a 9.15-fold increase in the apparent reaction rate constant for ATZ degradation. In addition, radical quenching experiments confirmed that singlet oxygen (¹O₂) and sulfate radicals (•SO₄^-) served as the primary reactive species. Furthermore, assessment using the Toxicity Estimation Software Tool (T.E.S.T) confirmed a significant reduction in the ecological toxicity of the degraded ATZ solution. This work not only presents an efficient photocatalytic-PMS synergistic degradation system but also offers a promising solution for the efficient removal of recalcitrant organic pollutants.