Degradation of 1,4-dioxane by reactive species generated during breakpoint chlorination: Proposed mechanisms and implications for water treatment and reuse
Degradation of 1,4-dioxane by reactive species generated during breakpoint chlorination: Proposed mechanisms and implications for water treatment and reuse
复制标题
断点氯化过程中产生的活性物质降解 1,4-二恶烷：拟议的机制以及对水处理和再利用的影响
DOI：
10.1016/j.hazl.2022.100054
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发表时间：
2022
影响因子：
--
通讯作者：
Liu, Haizhou
中科院分区：
文献类型：
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作者：
Patton, Samuel D.;Dodd, Michael C.;Liu, Haizhou
折点氯化是一种重要的化学过程，与饮用水回用的氯基高级氧化工艺和传统的水处理相关，研究了其氧化能力，反应物种的产生，以及对有机污染物降解的潜在影响。本工作描述了一种新认识的HO·自由基生成途径，在断点氯化过程中，可能在水处理中发挥重要作用，并检查HO·自由基和其他相关活性物种的行为及其潜在的形成途径。实验数据表明，1，4-二氧六环（1，4-D）的去除率与氯氨摩尔比呈正相关，当氯氨摩尔比达到1.5-2.0时，去除率迅速下降。过氧亚硝酸根（ONOO-）和过氧亚硝酸（ONOOH）被认为是导致断裂点过程中HO·形成的重要自由基来源。实验结果表明，加入碳酸盐的反应液对HO·的抑制作用比单纯用H2 CO 3 * /CO2和HCO 3-清除HO·的作用（显然是由于溶解CO2选择性地清除ONOOH/ONOO-）更强。这些实验也提供了证据，反应物种以外的HO·有助于1，4-D氧化。本研究的结果表明，断点氯化可以导致显着降解的有机污染物通过ONOOH/ONOO-介导的HO·和其他活性物种的形成，并可能被优化，以提高去除柠檬酸盐有机污染物的背景下，水的再利用，但由于谨慎的潜在增强含氮和其他消毒副产物的形成在这种条件下。
Breakpoint chlorination, an important chemical process relevant to chlorine-based advanced oxidation processes for potable reuse and to traditional water treatment, was investigated for its oxidative capacity, generation of reactive species, and potential impacts on organic contaminant degradation. This work describes a newly recognized HO•radical generation pathway during breakpoint chlorination that may play an important role in water treatment and examines the behavior of the HO•radical and other related reactive species and their potential formation pathways. Experimental data showed that the removal of 1,4-dioxane (1,4-D) positively correlated with chlorine-to-ammonia molar ratio until a molar ratio of ~1.5–2.0 was reached, above which removal efficiency rapidly decreased. Peroxynitrite (ONOO–) and peroxynitrous acid (ONOOH) are proposed as important radical sources that lead to the formation of HO•in the breakpoint process. This is supported by application oftert-butanol as a selective HO•scavenger and the observation that the amendment of reaction solutions with carbonate species suppressed oxidative capacity to a much greater extent than expected based solely on scavenging of HO•by H2CO3* /CO2and HCO3–(apparently due to selective scavenging of ONOOH/ONOO–by dissolved CO2). These experiments also provided evidence that reactive species other than HO•contributed to 1,4-D oxidation. The results of this study suggest that breakpoint chlorination can lead to significant degradation of organic contaminants via ONOOH/ONOO–-mediated formation of HO•and other reactive species and may potentially be optimized for enhanced removal of recalcitrant organic contaminants in the context of water reuse, though with due caution to the potential for enhancement of nitrogenous and other disinfection byproduct formation under such conditions.