Marron Emily L, Van Buren Jean, Cuthbertson Amy A, Darby Emily, von Gunten Urs, Sedlak David L
Department of Civil & Environmental Engineering, University of California, Berkeley, California 94720, United States.
NSF Engineering Research Center for Reinventing the Nation's Urban Water Infrastructure (ReNUWIt), Berkeley, California 94720, United States.
Environ Sci Technol. 2021 Mar 2;55(5):3305-3312. doi: 10.1021/acs.est.0c07660. Epub 2021 Feb 10.
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., NHCl). 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 s. 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.
用于水和废水处理的化学消毒剂会产生多种转化产物，包括羰基化合物（如饱和与不饱和醛类和酮类）。在与饮用水处理厂氯化以及配水系统中余氯应用相关的条件下进行的实验表明，α,β-不饱和羰基化合物在较宽的pH范围内能与游离氯和游离溴迅速反应，但与化合氯（即NHCl）反应缓慢。对于所研究的几乎所有11种α,β-不饱和羰基化合物，与游离氯反应的表观二级速率常数随次氯酸盐（OCl）浓度呈线性增加，得到与OCl反应的物种特异性二级速率常数，范围为0.21至12 M⁻¹s⁻¹。基于二级速率常数的预测表明，几种较为突出的α,β-不饱和羰基化合物（如丙烯醛、巴豆醛）中的很大一部分（即>60%）在配水系统中会被游离氯显著转化。利用核磁共振（NMR）以及气相色谱与高分辨率飞行时间质谱联用（GC-HRT-MS）对氯与丙烯醛、巴豆醛和甲基乙烯基酮反应的产物进行了初步鉴定。这些产物不含不饱和碳，在某些情况下还含有多个卤素。
