Oxidation of N-nitrosodimethylamine (NDMA) precursors with ozone and chlorine dioxide:: Kinetics and effect on NDMA formation potential
Oxidation of N-nitrosodimethylamine (NDMA) precursors with ozone and chlorine dioxide:: Kinetics and effect on NDMA formation potential
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DOI：
10.1021/es062484q
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发表时间：
2007-03-15
影响因子：
11.4
通讯作者：
von Gunten, Urs
中科院分区：
文献类型：
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作者：
Lee, Changha;Schmidt, Carsten;von Gunten, Urs
使用臭氧和二氧化氯 (ClO2) 研究水处理过程中 N-亚硝基二甲胺 (NDMA) 前体的氧化。模型 NDMA 前体（二甲胺 (DMA) 和 7 种叔胺）与臭氧反应的二阶速率常数（k(app)，pH 7 = 2.4 x 10(-1) 至 2.3 x 10(9) M-1 s(-1)），ClO2 (k(app)，pH 7 = 6.7 x 10(-3) 至 3.0 x 10(7) M-1 s(-1))和羟基 测定了自由基（(OH)-O-中心点）（pH 7 = 6.2 x 10(7) 至 1.4 x 10(10) M-1 s(-1) 时的 k(app)），这表明除二甲基甲酰胺 (DMFA) 外，所选的 NDMA 前体可以通过与臭氧直接反应而完全转化。在臭氧化过程中，DMFA 可能会通过二级氧化剂 (OH)-O-中心点的氧化而部分转化。 ClO2 还被证明可以有效地转化大多数前体，但 DMA 和 DMFA 除外。在该研究的第二部分中，测量了使用和不使用臭氧和 ClO2 预氧化的情况下合成水和天然水中的 NDMA 形成电位 (NDMA-FP)。在模型 NDMA 前体完全转化后，观察到 NDMA-FP 显着减少。臭氧化通常比 ClO2 更有效地减少 NDMA-FP。对于大多数前体，DMA 的形成可以解释模型 NDMA 前体完全转化后剩余的 NDMA-FP。相比之下，二甲基乙醇胺和二甲基二硫代氨基甲酸酯产生其他 NDMA 前体（不是 DMA）作为其氧化产物。臭氧和 ClO2 对几种天然水的预氧化表现出与模型 NDMA 前体的氧化相似的行为，对于各种天然水源，NDMA-FP 减少了 32-94%。
The oxidation of N-nitrosodimethylamine (NDMA) precursors during water treatment was investigated using ozone and chlorine dioxide (ClO2). Second-order rate constants for the reactions of model NDMA precursors (dimethylamine (DMA) and 7 tertiary amines) with ozone (k(app) at pH 7 = 2.4 x 10(-1) to 2.3 x 10(9) M-1 s(-1)), ClO2 (k(app) at pH 7 = 6.7 x 10(-3) to 3.0 x 10(7) M-1 s(-1)), and hydroxyl radical ((OH)-O-center dot) (k(app) at pH 7 = 6.2 x 10(7) to 1.4 x 10(10) M-1 s(-1)) were determined, which showed that the selected NDMA precursors, with the exception of dimethylformamide (DMFA) can be completely transformed via their direct reaction with ozone. During ozonation, DMFA may be partially transformed through oxidation by the secondary oxidant (OH)-O-center dot. ClO2 was also shown to effectively transform most of the precursors, with the exceptions of DMA and DMFA. In the second part of the study, the NDMA formation potentials (NDMA-FP) in synthetic and natural waters were measured with and without pre-oxidation with ozone and ClO2. A significant reduction in the NDMA-FPs was observed after complete transformation of the model NDMA precursors. Ozonation generally led to more effective reduction of the NDMA-FP than ClO2. For most of the precursors, the formation of DMA could account for the NDMA-FPs remaining after complete transformation of the model NDMA precursors. In contrast, dimethylethanolamine and dimethyldithiocarbamate yielded other NDMA precursors (not DMA) as their oxidation products. Pre-oxidation by ozone and ClO2 of several natural waters showed behavior similar to that of the oxidation of model NDMA precursors with a reduction of the NDMA-FP by 32-94% for various natural water sources.