Degradation of sulfonamide antibiotic via UV/MgO₂ system: kinetic, application, and mechanism

In response to antibiotic residues in the water, a novel advanced oxidation technology based on MgO₂ was used to remediate sulfamethazine (SMTZ) pollution in aquatic environments. Upon appropriate regulation, the remarkable removal efficiency of SMTZ was observed in a UV/MgO₂ system, and the pseudo-first-order reaction constant reached 0.4074 min^-1. In addition, the better performance of the UV/MgO₂ system in a weak acid environment was discovered. During the removal of SMTZ, the pathways of SMTZ degradation were deduced, including nitration, ring opening, and group loss. In the mineralization exploration, the further removal of residual products of SMTZ by the UV/MgO₂ system was visually demonstrated. The qualitative and quantitative researches as well as the roles of reactive species were valuated, which revealed the important role of ·O₂^-. Common co-existing substances in actual wastewater such as NO₃^- HA, Cl^-, Fe²⁺, Co²⁺, and Mn²⁺ can slightly inhibit the degradation of SMTZ in the UV/MgO₂ system. Finally, the capacity of efficient degradation of SMTZ in actual wastewater by the UV/MgO₂ system was proved. The results indicated that the innovative UV/MgO₂ system was of great practical application prospect in antibiotic residue wastewater remediation.