Oxygen Vacancy-Dominated\nActivation of Chlorite and\nOxidative Degradation of Sulfamethoxazole

Abstract

Oxygen vacancy-rich bismuth oxyhalides (BiOX, where X\n= Cl, Br,\nI) were successfully synthesized as heterogeneous catalysts for efficiently\nactivating chlorite to produce chlorine dioxide (ClO₂)\nas the prevailing reactive oxidized species (ROS) for sulfamethoxazole\n(SMX) degradation. Material characterization and density functional\ntheory (DFT) calculations show that BiOI possesses the highest oxygen\nvacancies, which act as highly active sites. Oxygen vacancies (OVs)\nnot only absorb chlorite but also improve the internal electron conduction\nefficiency between chlorite and metal ions. The best removal of SMX\n(84.3%) was achieved under neutral conditions using 70 mg of BiOI\nand 0.1 mM chlorite. It was discovered that ClO₂ is the\nprimary ROS, which was generated via two reactions that involved the\nformation of HOCl and Bi(IV). The minimal change in acute toxicity\nand the well-maintained performance in degrading pollutants indicated\nthe potential practical applications of the BiOI/chlorite system.\nThis work reveals a unique mechanism for the OV-mediated activation\nof chlorite, which highlights the potential advantages of activation\nvia heterogeneous metal oxides BiOX and supplies a new viewpoint for\nthe activation of chlorite for contaminant degradation.