Metronidazole Degradation by UV and UV/H 2 O 2 Advanced Oxidation Processes: Kinetics, Mechanisms, and Effects of Natural Water Matrices

Rongkui Su, Xiangrong Dai, Hanqing Wang, Zhixiang Wang, Zishi Li, Yonghua Chen, Yiting Luo () and Danxia Ouyang
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Rongkui Su: PowerChina Zhongnan Engineering Corporation Limited, Changsha 410004, China
Xiangrong Dai: PowerChina Zhongnan Engineering Corporation Limited, Changsha 410004, China
Hanqing Wang: College of Environmental Science and Engineering, Central South University of Forestry & Technology, Changsha 410004, China
Zhixiang Wang: College of Environmental Science and Engineering, Central South University of Forestry & Technology, Changsha 410004, China
Zishi Li: College of Environmental Science and Engineering, Central South University of Forestry & Technology, Changsha 410004, China
Yonghua Chen: College of Environmental Science and Engineering, Central South University of Forestry & Technology, Changsha 410004, China
Yiting Luo: Hunan First Normal University, Changsha 410114, China
Danxia Ouyang: College of Environmental Science and Engineering, Central South University of Forestry & Technology, Changsha 410004, China

IJERPH, 2022, vol. 19, issue 19, 1-19

Abstract: Advanced oxidation technology represented by hydroxyl radicals has great potential to remove residual antibiotics. In this study, we systematically compared the metronidazole (MTZ) degradation behavior and mechanism in the UV and UV/H 2 O 2 systems at pH 3.00 condition. The results show that the initial reaction rates were 0.147 and 1.47 µM min −1 in the UV and UV/H 2 O 2 systems, respectively. The main reason for the slow direct photolysis of MTZ is the relatively low molar absorption coefficient (2645.44 M −1 cm −1 ) and quantum yield (5.9 × 10 −3 mol Einstein −1 ). Then, we measured k MTZ , OH • as 2.79 (±0.12) × 10 9 M −1 s −1 by competitive kinetics, and calculated k MTZ , OH • and [ OH • ] SS as 2.43 (±0.11) × 10 9 M −1 s −1 and 2.36 × 10 −13 M by establishing a kinetic model based on the steady-state hypothesis in our UV/H 2 O 2 system. The contribution of direct photolysis and • OH to the MTZ degradation was 9.9% and 90.1%. • OH plays a major role in the MTZ degradation, and • OH was the main active material in the UV/H 2 O 2 system. This result was also confirmed by MTZ degradation and radicals’ identification experiments. MTZ degradation increases with H 2 O 2 dosage, but excessive H 2 O 2 had the opposite effect. A complex matrix has influence on MTZ degradation. Organic matter could inhibit the degradation of MTZ, and the quenching of the radical was the main reason. NO 3 − promoted the MTZ degradation, while SO 4 2 − and Cl − had no effect. These results are of fundamental and practical importance in understanding the MTZ degradation, and to help select preferred processes for the optimal removal of antibiotics in natural water bodies, such as rivers, lakes, and groundwater

Keywords: hydroxyl radical; metronidazole; antibiotic; steady-state kinetic model; complex matrix (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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