Natural Organic Matter Exposed to Sulfate Radicals Increases Its Potential to Form Halogenated Disinfection Byproducts

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• 作者：Junhe Lu ; Wei Dong ; Yuefei Ji ; Deyang Kong ; Qingguo Huang
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：May 17, 2016
• 年：2016
• 卷：50
• 期：10
• 页码：5060-5067
• 全文大小：516K
• 年卷期：0
• ISSN：1520-5851

文摘

Sulfate radical-based advanced oxidation processes (SR-AOPs) are considered as viable technologies to degrade a variety of recalcitrant organic pollutants. This study demonstrates that o-phthalic acid (PA) could lead to the formation of brominated disinfection byproducts (DBPs) in SR-AOPs in the presence of bromide. However, PA does not generate DBPs in conventional halogenation processes. We found that this was attributed to the formation of phenolic intermediates susceptible to halogenation, such as salicylic acid through the oxidation of PA by SO₄^•–. In addition, reactive bromine species could be generated from Br^– oxidation by SO₄^•–. Similar in situ generation of phenolic functionalities likely occurred by converting carboxylic substituents on aromatics to hydroxyl when natural organic matter (NOM) was exposed to trace level SO₄^•–. It was found that such structural reconfiguration led to a great increase in the reactivity of NOM toward free halogen and, thus, its DBP formation potential. After a surface water sample was treated with 0.1 μM persulfate for 48 h, its potential to form chloroform, trichloroacetic acid, and dichloroacetic acid increased from 197.8, 54.3, and 27.6 to 236.2, 86.6, and 57.6 μg/L, respectively. This is the first report on possible NOM reconfiguration upon exposure to low-level SO₄^•– that has an implication in DBP formation. The findings highlight potential risks associated with SO₄^•–-based oxidation processes and help to avoid such risks in design and operation.