Monochloramination of Oxytetracycline: Kinetics,Mechanisms, Pathways,and Disinfection By‐Products Formation |
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| Authors: | Xiangyu Bi Bin Xu Yi‐Li Lin Chen‐Yan Hu Tao Ye Cao Qin |
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| Institution: | 1. State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze Aquatic Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, P. R. China;2. Department of Safety, Health and Environmental Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung, Taiwan, ROC;3. College of Energy and Environment Engineering, Shanghai University of Electric Power, Shanghai, P. R. China |
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| Abstract: | This study investigated the degradation kinetics, formation of disinfection by‐products (DBPs), and degradation pathways during monochloramination of oxytetracycline (OTC). The degradation kinetics can be well described by a second‐order kinetic model, first‐order in monochloramine (NH2Cl), and first‐order in OTC. Reaction of OTC with NH2Cl shows a high reactivity, with the apparent rate constant of 17.64/M/s at pH 7. The apparent rate constant declined as pH increased from 5 to 10. Six DBPs were detected during monochloramination of OTC, including chloroform (CF), 1,1‐dichloro‐2‐propanone (1,1‐DCP), 1,1,1‐trichloro‐2‐propanone (1,1,1‐TCP), dichloroacetonitrile (DCAN), trichloronitromethane (TCNM), and N‐nitrosodimethlyamine (NDMA). CF, DCAN and NDMA had the maximum yields at neutral pH, while 1,1‐DCP and 1,1,1‐TCP had the maximum yields at pH 4. However, TCNM concentration increased as pH increased. Degradation pathways of OTC monochloramination were then proposed. Hydroxylation and Cl‐substitution are found to be the dominant mechanisms in monochloramination of OTC. |
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| Keywords: | Aquatic environment N‐Nitrosodimethlyamine Rate constant Tetracyclines |
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