Role of Reactive Halogen Species in Disinfection Byproduct Formation during Chlorine Photolysis
Role of Reactive Halogen Species in Disinfection Byproduct Formation during Chlorine Photolysis
复制标题
DOI：
10.1021/acs.est.0c02039
复制
发表时间：
2020-08-04
影响因子：
11.4
通讯作者：
Remucal, Christina K.
中科院分区：
文献类型：
--
作者：
Bulman, Devon Manley;Remucal, Christina K.
氯光解过程中产生的多种活性氧化剂可有效降解水处理过程中的有机污染物，但它们在消毒副产物（DBP）形成中的作用尚不清楚。氯的光解溶解有机物（DOM）的组成和DBP的形成的影响进行了研究，使用后收集的湖水混凝，絮凝，过滤，在pH 6.5和pH 8.5的照射在三个波长（254，311，和365 nm）。与超纯水相比，饮用水中羟基自由基和氯自由基的稳态浓度降低了38-100%，这主要归因于天然水成分的自由基清除。氯光解通过多种机制转化DOM，产生更多脂肪族性质的DOM，并含有通过高分辨率质谱检测到的新型高分子量氯化消毒副产物。淬灭实验表明，活性氯物种是部分负责卤代DOM，卤代乙酸，卤代乙腈的形成，而三卤甲烷的形成减少氯光解。此外，DOM的转化主要是由于直接光解改变DOM，使其与氯的反应性更强，这也有助于在氯光解过程中增强新型DBP的形成。
The multiple reactive oxidants produced during chlorine photolysis effectively degrade organic contaminants during water treatment, but their role in disinfection byproduct (DBP) formation is unclear. The impact of chlorine photolysis on dissolved organic matter (DOM) composition and DBP formation is investigated using lake water collected after coagulation, flocculation, and filtration at pH 6.5 and pH 8.5 with irradiation at three wavelengths (254, 311, and 365 nm). The steady-state concentrations of hydroxyl radical and chlorine radical decrease by 38-100% in drinking water compared to ultrapure water, which is primarily attributed to radical scavenging by natural water constituents. Chlorine photolysis transforms DOM through multiple mechanisms to produce DOM that is more aliphatic in nature and contains novel high molecular weight chlorinated DBPs that are detected via high-resolution mass spectrometry. Quenching experiments demonstrate that reactive chlorine species are partially responsible for the formation of halogenated DOM, haloacetic acids, and haloacetonitriles, whereas trihalomethane formation decreases during chlorine photolysis. Furthermore, DOM transformation primarily due to direct photolysis alters DOM such that it is more reactive with chlorine, which also contributes to enhanced formation of novel DBPs during chlorine photolysis.