Curtin Water Quality Research Centre, Chemistry, School of Molecular and Life Sciences, Curtin University, GPO Box U1987, Perth, 6845, Australia.
Environ Sci Process Impacts. 2020 Mar 1;22(3):653-662. doi: 10.1039/c9em00603f. Epub 2020 Mar 9.
The use of monochloramine as an alternative disinfectant to chlorine in drinking water treatment can lead to increased formation of emerging nitrogenous halogenated disinfection by-products (DBPs), even when the formation of regulated halogenated DBPs has decreased. In this study, we investigated formation of the semivolatile haloacetonitriles (HANs) from model nitrogen-containing compounds (6 amines, 1 amide, 6 amino acids, and 2 nitrogen-containing aromatic chemicals) and natural organic matter (NOM) reference materials after chloramination. In agreement with previous studies, most amino acids formed dichloroacetonitrile (DCAN). Additionally, DCAN formed from two amines containing aromatic rings (N,N-dimethylaniline and 3-(dimethylamino-methyl)indole) and the two nitrogen-containing aromatic chemicals (cotinine and phenytoin). This is the first report of DCAN formation from these precursors. DCAN also formed after chloramination of NOM reference materials, with the highest formation from the NOM material with the highest aromaticity. The results provide new evidence of a DCAN formation pathway from cleavage of activated aromatic structures after electrophilic substitution of chlorine and addition of monochloramine to the ring system. In particular, the results suggest that the previously proposed aldehyde pathway from the amino acid group is not responsible for the majority of DCAN formation from amino acids with an activated aromatic ring system. This newly proposed formation pathway for DCAN from activated aromatic organic matter has significant implications for NOM removal during water treatment to minimise DBP formation. Studies using N-labelled monochloramine showed that there was significant incorporation of nitrogen from monochloramine into DCAN, demonstrating that monochloramine disinfection promotes the formation of HANs.
使用一氯胺作为饮用水处理中的替代消毒剂，可能会导致新兴含氮卤代消毒副产物（DBP）的形成增加，即使受管制的卤代 DBP 的形成减少了也是如此。在这项研究中，我们研究了氯胺化后从模型含氮化合物（6 种胺、1 种酰胺、6 种氨基酸和 2 种含氮芳香化学品）和天然有机物（NOM）参考材料中形成半挥发性卤乙腈（HANs）的情况。与先前的研究一致，大多数氨基酸形成了二氯乙腈（DCAN）。此外，两种含芳香环的胺（N，N-二甲基苯胺和 3-（二甲基氨基甲基）吲哚）和两种含氮芳香化学品（可替宁和苯妥英）也形成了 DCAN。这是首次报道这些前体形成 DCAN。在 NOM 参考材料的氯胺化后，也形成了 DCAN，其中具有最高芳香度的 NOM 材料的形成量最高。这些结果为氯的亲电取代和一氯胺加成到环系后，从活化的芳香结构裂解形成 DCAN 的途径提供了新的证据。特别是，这些结果表明，以前从含活化芳香环系的氨基酸提出的醛途径不是大多数 DCAN 形成的主要原因。这种从活化芳香有机物形成 DCAN 的新途径对水处理过程中去除 NOM 以最小化 DBP 形成具有重要意义。使用 N 标记的一氯胺的研究表明，一氯胺中有大量的氮掺入到 DCAN 中，这表明一氯胺消毒促进了 HANs 的形成。
