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Title: Reactions of α,β-Unsaturated Carbonyls with Free Chlorine, Free Bromine, and Combined Chlorine.

Authors: Marron, Emily L; Van Buren, Jean; Cuthbertson, Amy A; Darby, Emily; von Gunten, Urs; Sedlak, David L

Published In Environ Sci Technol, (2021 03 02)

Abstract: Chemical disinfectants employed in water and wastewater treatment can produce a variety of transformation products, including carbonyl compounds (e.g., saturated and unsaturated aldehydes and ketones). Experiments conducted under conditions relevant to chlorination at drinking water treatment plants and residual chlorine application in distribution systems indicate that α,β-unsaturated carbonyl compounds readily react with free chlorine and free bromine over a wide pH range but react slowly with combined chlorine (i.e., NH2Cl). For nearly all of the 11 α,β-unsaturated carbonyl compounds studied, the apparent second-order rate constants for the reaction with free chlorine increased in a linear manner with hypochlorite (OCl-) concentrations, yielding species-specific second-order rate constants for the reaction with OCl- ranging from 0.21 to 12 M-1 s-1. Predictions based on the second-order rate constants indicate that a substantial fraction (i.e., >60%) of several of the more prominent α,β-unsaturated carbonyls (e.g., acrolein, crotonaldehyde) will be transformed to an appreciable extent in distribution systems by free chlorine. Products from the reaction of chlorine with acrolein, crotonaldehyde, and methyl vinyl ketone were tentatively identified using nuclear magnetic resonance (NMR) and gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-HRT-MS). These products lacked unsaturated carbons and, in some cases, contained multiple halogens.

PubMed ID: 33565865 Exiting the NIEHS site

MeSH Terms: Bromine; Chlorine; Disinfectants*; Kinetics; Water Pollutants, Chemical*; Water Purification*

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