Laboratoire de Chimie et Microbiologie de l'Eau (CNRS UMR 6008), Université de Poitiers - ENSIP, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France.
Water Res. 2011 May;45(10):3164-74. doi: 10.1016/j.watres.2011.03.035. Epub 2011 Mar 26.
Disinfection with chloramines is often used to reduce the production of regulated disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). However, chloramination can lead to the formation of N-nitrosamines, including N-nitrosodimethylamine (NDMA), a probable human carcinogen. Previous research used dimethylamine (DMA) as a model precursor of NDMA, but certain widely used tertiary dimethylamines (e.g. the pharmaceutical ranitidine) show much higher conversion rates to NDMA than DMA. This study investigates the NDMA formation potential of several tertiary amines including pharmaceuticals and herbicides. The reactivity of these molecules with monochloramine (NH(2)Cl) is studied through the formation of NDMA, and other halogenated DBPs such as haloacetonitriles (HANs) and AOX (Adsorbable Organic Halides). Several compounds investigated formed NDMA in greater amounts than DMA, revealing the importance of structural characteristics of tertiary amines for NDMA formation. Among these compounds, the pharmaceutical ranitidine showed the highest molar conversion to NDMA. The pH and dissolved oxygen content of the solution were found to play a major role for the formation of NDMA from ranitidine. NDMA was formed in higher amounts at pH around pH 8 and a lower concentration of dissolved oxygen dramatically decreased NDMA yields. These findings seem to indicate that dichloramine (NHCl(2)) is not the major oxidant involved in the formation of NDMA from ranitidine, results in contradiction with the reaction mechanisms proposed in the literature. Dissolved oxygen was also found to influence the formation of other oxygen-containing DBPs (i.e. trichloronitromethane and haloketones). The results of this study identify several anthropogenic precursors of NDMA, indicating that chloramination of waters impacted by these tertiary amines could lead to the formation of significant amounts of NDMA and other non-regulated DBPs of potential health concern (e.g. dichloroacetonitrile or trichloronitromethane). This could be of particular importance for the chloramination of wastewater effluents, especially during water reuse processes.
氯胺消毒常用于减少三卤甲烷 (THMs) 和卤乙酸 (HAAs) 等受管制消毒副产物 (DBPs) 的生成。然而，氯胺消毒会导致亚硝胺的形成，包括亚硝二甲胺 (NDMA)，这是一种可能的人类致癌物。先前的研究使用二甲胺 (DMA) 作为 NDMA 的模型前体，但某些广泛使用的叔胺（例如药物雷尼替丁）转化为 NDMA 的转化率远高于 DMA。本研究调查了几种包括药物和除草剂在内的叔胺的 NDMA 生成潜力。通过 NDMA 的形成以及卤代 DBPs（如卤乙腈 (HANs) 和 AOX（可吸附有机卤化物））的形成，研究了这些分子与一氯胺 (NH2Cl) 的反应活性。研究中发现，几种化合物形成的 NDMA 多于 DMA，这表明叔胺的结构特征对 NDMA 生成的重要性。在这些化合物中，药物雷尼替丁显示出向 NDMA 转化的最高摩尔转化率。发现溶液的 pH 值和溶解氧含量对雷尼替丁生成 NDMA 起着重要作用。在 pH 值约为 8 且溶解氧浓度较低的情况下，NDMA 的生成量较高，而溶解氧浓度的急剧降低会显著降低 NDMA 的产率。这些发现似乎表明，二氯胺 (NHCl2) 不是形成雷尼替丁 NDMA 的主要氧化剂，这与文献中提出的反应机制相矛盾。溶解氧也被发现会影响含氧 DBPs（即三氯硝基甲烷和卤代酮）的形成。本研究的结果确定了几种 NDMA 的人为前体，表明受这些叔胺影响的水的氯胺消毒可能会导致形成大量 NDMA 和其他非受管制的潜在健康关注的 DBPs（例如二氯乙腈或三氯硝基甲烷）。这对于废水处理厂的氯胺消毒尤其重要，尤其是在水再利用过程中。
