Degradation of sulfadiazine by UV/Oxone: roles of reactive oxidative species and the formation of disinfection byproducts
2022
Chen, Juxiang | Dai, Caiqiong | Zhu, Yanping | Gao, Yuqiong | Chu, Wenhai | Gao, Naiyun | Wang, Qiongfang
Sulfadiazine (SDZ) is a typical persistent sulfonamide antibiotic, which has been widely detected in natural drinking water sources. The degradation of SDZ by UV/Oxone (potassium monopersulfate compound) was explored in this study. The results showed that Cl⁻ can effectively activate PMS to promote rapid degradation of SDZ in the Oxone process by forming chlorine in the system. Radical quenching tests suggested that radical oxidation, including HO•, SO₄•⁻, and reactive chlorine species (RCS), played an important role by UV/Oxone. It further verified that concentration and distribution of HO•, SO₄•⁻, and RCS were pH-dependent; RCS act as a major contributor at pH 6.0 and pH 7.0 to degrade SDZ in this process. The SDZ degradation rate was firstly increased and then decreased by Cl⁻ and HCO₃⁻ (0–10 mM); HA (0–10 mg L⁻¹) exhibited insignificant influence on SDZ degradation. The degradation pathways of SDZ during UV/Oxone and formation pathways of five disinfection byproducts during subsequent chlorination were proposed. The possible DBP precursors formed by SO₂ extrusion, hydroxylation, and chlorination of SDZ during UV/Oxone pre-oxidation.
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