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Assessing the N-Nitrosamine Formation Potential of Selected Ionic Liquids, 1-Ethyl-3-Methylimidazolium Bromide and 1-Ethyl-1-Methylpyrrolidinium Bromide, Treated With the Drinking Water Disinfectant Monochloramine
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- Author / Creator
- Vander Meulen, Ian J
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Ionic liquids (ILs) are increasingly used in industrial processes as “green chemicals” because of unique properties of low volatility and customizability. ILs can be used to enable novel processes and/or replace conventional organic solvents in a wide variety of applications. Widespread use may increase the risk of accidental release of IL-containing industrial wastes into environmental waters. Most ILs are highly water soluble, and have estimated environmental half-lives of several days to a month. IL cations often consist of aromatic or alkyl quaternary amines that resemble previously confirmed N-nitrosamine (NAs) precursors. NAs are confirmed animal carcinogens and classified as probable human carcinogens. NAs are also potent, estimated to have negative health effects at ng/L concentrations. Therefore, this study sought to evaluate two representative ILs, 1-ethyl-1-methylpyrroldinium bromide (EMPyrBr) and 1-ethyl-3-methylimidazolium bromide (EMImBr), for their nitrosamine formation potential. Each IL species was reacted with pre-formed monochloramine under varied reaction conditions. After 24h, samples were extracted from water by liquid-liquid extraction using dichloromethane. The extracts were analyzed to determine the produced nitrosamines using HPLC-MS/MS with multiple reaction monitoring mode. Quantification of NAs was achieved using a deuterated surrogate standard, and deuterated internal standard. Both EMImBr and EMPyrBr produced NAs during reactions with monochloramine: EMImBr acted as a precursor to N-nitrosomethylethylamine (NMEA), and EMPyrBr acted as a precursor to NMEA and N-nitrosopyrrolidine. EMPyrBr was a more productive precursor under all conditions evaluated, with a yield on the same order of magnitude as polydiallydimethylammonium chloride, a confirmed N-nitrosodimethylamine precursor. This study emphasizes the importance of prevention of environmental discharge of ILs to water bodies, but also highlights a need for further evaluation of potential lifecycle impacts of ILs prior to their wide ranging applications.Attempts were made to quantify EMImBr by LC-UV before and after treatment with NH2Cl to measure degradation during reactions. Results of LC-UV were indicative of alternate product formation. This initial study suggests future studies on identification of major product(s) of this reaction and to elucidate reaction mechanism(s).These results suggest that disposal of ILs should be carefully considered so as to prevent contamination of drinking water sources. IL-based drinking water treatment technologies should also attempt to minimize IL contamination of finished drinking water.
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- Graduation date
- Spring 2019
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.