Formation of Multiple Nitrosamines from the Ozonation of Corresponding Precursor Secondary Amines: Influencing Factors and Transformation Mechanisms
Since nitrosamine disinfection by products is highly carcinogenic, they have attracted considerable attention due to their increased presence in ambient waterways and potable water supplies. For the present study, the potential formation of nitrosamines from corresponding precursor secondary amines during ozonation was investigated. The results revealed that five nitrosamines were observed during the ozonation of their corresponding secondary amines. The molar yields initially increased and then decreased with longer contact times and higher ozone doses. These phenomena indicated that ozone not only promoted nitrosamine formation but also degraded the formed nitrosamines. High pH had a positive influence on nitrosamine formation at room temperature. Further, coexisting substances including nitrate, nitrite, humic acid, and tert-butanol inhibited the generation of nitrosamines due to hydroxyl radical (·OH) competition and scavengers, whereas in the presence of hydroxylamine, nitrosamine formation increased considerably without ozone due to its capacity for independent formation between secondary amines and hydroxylamine. Further, the generation of nitrosamines from secondary amines was primarily attributed to O3 and ·OH oxidation, which was produced through the decomposition of ozone. The transformation pathways were mainly comprised of the indirect routes between the O3/·OH intermediates. The findings of this study were helpful toward expanding the knowledge of nitrosamine formation during the corresponding precursor secondary amine ozonation process.
KeywordsSecondary amines Nitrosamines Ozonation Influencing factors Transformation pathways
We thank Mr. Frank Boehm from Lakehead University in Canada, for reviewing the paper and correcting the English.
This work was supported by the National Special Funding Project for Water Pollution Control and Management of China (2014ZX07405001); the National Natural Science Foundation of China (No. 51208184); the special fund of Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (Project No. 18K04KLDWST); and the Technology Department of the Henan Science and Technology Fund Project (No. 172102310590).
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
- U.S. Environmental Protection Agency. (2009). Contaminant Candidate List3 (CCL3). https://www.epa.gov/ccl/contaminant-candidate-list-3-ccl-3. Accessed 31 Aug 2018.
- U.S. Environmental Protection Agency. (2012). Integrated Risk Information System: N-nitrosodimethylamine (CASRN 62-75-9). https://cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=45. . Accessed 31 Aug 2018.
- Wang, W. F., Yu, J. W., An,W., Yang, M. (2016). Occurrence and profiling of multiple nitrosamines in source water and drinking water of China. Science of the Total Environment, 551–552, 489–495.Google Scholar
- Zhao, Y., Boyd, J. M.,Woodbeck, M., Andrews, R. C., Qin, F., Hrudey, S. E., Li, X. (2008). Formation of N-nitrosamines from eleven disinfection treatments of seven different surface waters. Environmental Science Technology 42(13), 4857–4862.Google Scholar