Abatement of Nitrophenol in Aqueous Solution by HOCl and UV/HOCl Processes: Kinetics, Mechanisms, and Formation of Chlorinated Nitrogenous Byproducts
HOCl and UV activated HOCl (UV/HOCl) have been applied for water disinfection and abatement of organic contaminants. However, the production of toxic byproducts in the HOCl and UV/HOCl treatment should be scrutinized. This contribution comparatively investigated the elimination of 4-nitrophenol and...
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MDPI AG
2023-11-01
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| author | Xiaoci Li Yan Cai Junhe Lu Jean-Marc Chovelon Jing Chen Canlan Jiang Yuefei Ji |
| author_facet | Xiaoci Li Yan Cai Junhe Lu Jean-Marc Chovelon Jing Chen Canlan Jiang Yuefei Ji |
| author_sort | Xiaoci Li |
| collection | DOAJ |
| description | HOCl and UV activated HOCl (UV/HOCl) have been applied for water disinfection and abatement of organic contaminants. However, the production of toxic byproducts in the HOCl and UV/HOCl treatment should be scrutinized. This contribution comparatively investigated the elimination of 4-nitrophenol and the generation of chlorinated byproducts in HOCl and UV/HOCl treatment processes. 61.4% of 4-nitrophenol was removed by UV/HOCl in 5 min with HOCl dose of 60 μM, significantly higher than that by UV (3.3%) or HOCl alone (32.0%). Radical quenching test showed that HO<sup>•</sup> and Cl<sup>•</sup> played important roles in UV/HOCl process. 2-Chloro-4-nitrophenol and 2,6-dichloro-4-nitrophenol were generated consecutively in HOCl process; but their formation was less in the UV/HOCl process. Trichloronitromethane (TCNM) was only found in the UV/HOCl process, and its production increased with increasing HOCl dosage. Besides chlorinated products hydroxylated and dinitrated products were also identified in the UV/HOCl process. Transformation pathways involving electrophilic substitution, hydroxylation, and nitration were proposed for 4-nitrophenol transformation in the UV/HOCl process. Wastewater matrix could significantly promote the transformation of 4-nitrophenol to 2-chloro-4-nitrophenol in UV/HOCl process. Results of this study are helpful to advance the understanding of the transformation of nitrophenolic compounds and assess the formation potential of chlorinated byproducts in HOCl and UV/HOCl disinfection processes. |
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| language | English |
| last_indexed | 2024-03-09T01:40:52Z |
| publishDate | 2023-11-01 |
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| spelling | doaj.art-36b0483069184ecdacca2fde37411a0a2023-12-08T15:28:11ZengMDPI AGWater2073-44412023-11-011523403810.3390/w15234038Abatement of Nitrophenol in Aqueous Solution by HOCl and UV/HOCl Processes: Kinetics, Mechanisms, and Formation of Chlorinated Nitrogenous ByproductsXiaoci Li0Yan Cai1Junhe Lu2Jean-Marc Chovelon3Jing Chen4Canlan Jiang5Yuefei Ji6College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, ChinaCollege of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, ChinaCollege of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, ChinaUniv Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626 Villeurbanne, FranceCollege of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, ChinaCollege of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, ChinaCollege of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, ChinaHOCl and UV activated HOCl (UV/HOCl) have been applied for water disinfection and abatement of organic contaminants. However, the production of toxic byproducts in the HOCl and UV/HOCl treatment should be scrutinized. This contribution comparatively investigated the elimination of 4-nitrophenol and the generation of chlorinated byproducts in HOCl and UV/HOCl treatment processes. 61.4% of 4-nitrophenol was removed by UV/HOCl in 5 min with HOCl dose of 60 μM, significantly higher than that by UV (3.3%) or HOCl alone (32.0%). Radical quenching test showed that HO<sup>•</sup> and Cl<sup>•</sup> played important roles in UV/HOCl process. 2-Chloro-4-nitrophenol and 2,6-dichloro-4-nitrophenol were generated consecutively in HOCl process; but their formation was less in the UV/HOCl process. Trichloronitromethane (TCNM) was only found in the UV/HOCl process, and its production increased with increasing HOCl dosage. Besides chlorinated products hydroxylated and dinitrated products were also identified in the UV/HOCl process. Transformation pathways involving electrophilic substitution, hydroxylation, and nitration were proposed for 4-nitrophenol transformation in the UV/HOCl process. Wastewater matrix could significantly promote the transformation of 4-nitrophenol to 2-chloro-4-nitrophenol in UV/HOCl process. Results of this study are helpful to advance the understanding of the transformation of nitrophenolic compounds and assess the formation potential of chlorinated byproducts in HOCl and UV/HOCl disinfection processes.https://www.mdpi.com/2073-4441/15/23/4038UV/HOClreactive chlorine speciesnitrogenous disinfection byproductsnitrogen dioxide radicaltrichloronitromethane |
| spellingShingle | Xiaoci Li Yan Cai Junhe Lu Jean-Marc Chovelon Jing Chen Canlan Jiang Yuefei Ji Abatement of Nitrophenol in Aqueous Solution by HOCl and UV/HOCl Processes: Kinetics, Mechanisms, and Formation of Chlorinated Nitrogenous Byproducts Water UV/HOCl reactive chlorine species nitrogenous disinfection byproducts nitrogen dioxide radical trichloronitromethane |
| title | Abatement of Nitrophenol in Aqueous Solution by HOCl and UV/HOCl Processes: Kinetics, Mechanisms, and Formation of Chlorinated Nitrogenous Byproducts |
| title_full | Abatement of Nitrophenol in Aqueous Solution by HOCl and UV/HOCl Processes: Kinetics, Mechanisms, and Formation of Chlorinated Nitrogenous Byproducts |
| title_fullStr | Abatement of Nitrophenol in Aqueous Solution by HOCl and UV/HOCl Processes: Kinetics, Mechanisms, and Formation of Chlorinated Nitrogenous Byproducts |
| title_full_unstemmed | Abatement of Nitrophenol in Aqueous Solution by HOCl and UV/HOCl Processes: Kinetics, Mechanisms, and Formation of Chlorinated Nitrogenous Byproducts |
| title_short | Abatement of Nitrophenol in Aqueous Solution by HOCl and UV/HOCl Processes: Kinetics, Mechanisms, and Formation of Chlorinated Nitrogenous Byproducts |
| title_sort | abatement of nitrophenol in aqueous solution by hocl and uv hocl processes kinetics mechanisms and formation of chlorinated nitrogenous byproducts |
| topic | UV/HOCl reactive chlorine species nitrogenous disinfection byproducts nitrogen dioxide radical trichloronitromethane |
| url | https://www.mdpi.com/2073-4441/15/23/4038 |
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