Enhancing degradation of novel brominated flame retardants by sulfate modified C3N4: Synergistic effect of photocatalytic oxidation and reduction processes

Abstract

Novel brominated flame retardants (NBFRs) pose serious risks to aquatic organisms and human health due to their persistence and toxicity. Herein, sulfate ions (SO₄^2-) decorated C₃N₄ (SO₄^2-@CN) photocatalyst material was synthesized for the rapid degradation of NBFRs by a synergistic effect of photocatalytic oxidation and reduction reactions. Compared with bare C₃N₄, the SO₄^2-@CN exhibited efficient photocatalytic NBFRs removal performance. The degradation rates constant of hexabromobenzene and pentabromotoluene by SO₄^2-@CN were 0.177 and 0.0906 min^-1, respectively, which were 2.9 and 6.7 times higher than that by C₃N₄. It was confirmed that SO₄^2-@CN could generate more active substances (such as sulfate radicals, and hydroxyl radicals) and promote the oxidation of NBFRs. Meanwhile, SO₄^2- accelerated the separation of photogenerated electron-holes by promoting the formation of hydrogenated structures, allowing more photogenerated electrons to participate in the debromination reduction process. This work provides a new insight for the practical application of visible light driven photocatalytic technology in NBFRs residues degradation.