1. Fate of quaternary ammonium compounds upon the UV/monochloramine process: Kinetics, transformation pathways and the formation of N-nitroso-N-methyl-N-alkylamines.
- Author
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Kong, Angel Wing-Yin, Law, Japhet Cheuk-Fung, and Leung, Kelvin Sze-Yin
- Subjects
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TRIMETHYL ammonium compounds , *QUATERNARY ammonium compounds , *AMMONIUM compounds , *MASS spectrometers , *WATER sampling - Abstract
Quaternary ammonium compounds (QACs) are widely detected in the aquatic environment due to their extensive use in a wide array of antibacterial products during the pandemic. In the current study, UV/monochloramine (UV/NH 2 Cl) was used to degrade three typical QACs, namely benzalkonium compounds (BACs), dialkyl dimethyl ammonium compounds (DADMACs), and alkyl trimethyl ammonium compounds (ATMACs). This process achieved high efficiency in removing BACs from water samples. The transformation products of QACs treated with UV/NH 2 Cl were identified and characterized using a high-resolution mass spectrometer, and transformation pathways were proposed. The formation of N-nitroso-N-methyl-N-alkylamines (NMAs) and N-nitrosodimethylamine (NDMA) were observed during QAC degradation. The molar formation yield of NDMA from C 12 -BAC was 0.04 %, while yields of NMAs reached 1.05 %. The ecotoxicity of NMAs derived from QACs was predicted using ECOSAR software. The increased toxicity could be attributed to the formation of NMAs with longer alkyl chains; these NMAs, exhibited a one order of magnitude increase in toxicity compared to their parent QACs. This study provides evidence that QACs are the specific and significant precursors of NMAs. Greater attention should be given to NMA formation and its potential threat to the ecosystem, including humans. [Display omitted] • Transformation pathways for QACs in UV/NH 2 Cl process are proposed for the first time. • Aliphatic QACs were poorly removed by UV/NH 2 Cl process. • QACs are specific and significant precursors of NMAs. • Molar formation yield of C 12 -NMA from C 12 -BAC was 26 times higher than of NDMA. • NMAs derived from QACs were more toxic than NDMA. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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