Institute of Environmental Engineering, National Sun Yat-sen University, Kaohsiung, 804, Taiwan; Aerosol Science and Research Center, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
Institute of Environmental Engineering, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
Chemosphere. 2021 Mar;267:128922. doi: 10.1016/j.chemosphere.2020.128922. Epub 2020 Nov 10.
Amine-containing pharmaceuticals formed nitrosamines that are nitrogenous disinfection byproducts of public concerns due to their carcinogenicity. The objective of this study was to investigate the co-effect of additional inorganic nitrogen in different forms (ammonium, nitrite, and nitrate) and different disinfection approaches (chlorination, monochloramination, dichloramination, and two-step chlorination) on eight nitrosamine formation from four widely used pharmaceuticals. N-nitrosodimethylamine (NDMA) was the main species formed. The presence of N-nitrosomethylethylamine (NMEA), nitrosomorpholine (NMor), and N-nitrosopiperidine (NPip) was found in certain experiments. For one-step chlorination, the influential factors, in decreasing order of importance, were the molecular structural characteristics of the pharmaceutical, oxidation method, and presence and form of additional nitrogen. In four pharmaceuticals with comparative structures, the availability of amine intermediates during degradation was the key to higher nitrosamine yields. Monochloramine significantly enhanced nitrosamine formation from four pharmaceuticals. NDMA formation by adding hypochlorous acid and ammonium separately were lower than those during monochloramination. During two-step chlorination, NDMA formation was enhanced at certain pre-chlorine doses (e.g., a Cl/N molar ratio of 20 or 4). The pre-chlorine dose changed the Cl/N ratio. As the ratio was increased, the combined chlorine residual was formed and decreased. When the ratio was high, breakpoint chlorination possibly occurred enhancing NDMA formation. While NDMA formation was successfully inhibited by two-step chlorination, ammonium brought the NDMA yields of these pharmaceuticals back to the range observed in chloramination, suggesting the importance of ammonium control for limiting NDMA formation from pharmaceuticals during two-step chlorination.
含胺药物会形成亚硝胺，由于其致癌性，这些亚硝胺是备受公众关注的氮类消毒副产物。本研究的目的是考察不同形态（铵、亚硝酸盐和硝酸盐）的外加无机氮和不同消毒方法（氯化、单氯胺化、二氯胺化和两步氯化）对 4 种常用药物中 8 种亚硝胺形成的协同作用。结果表明，N-亚硝基二甲胺（NDMA）是主要生成产物，某些实验中还发现了 N-亚硝基甲乙胺（NMEA）、亚硝吗啉（NMor）和 N-亚硝基哌啶（NPip）。对于一步氯化，影响因素的重要性依次为药物的分子结构特征、氧化方法以及外加氮的存在和形态。在具有相似结构的 4 种药物中，胺中间体在降解过程中的可得性是产生更高亚硝胺收率的关键。一氯胺显著增强了 4 种药物中亚硝胺的生成。单独添加次氯酸和铵所产生的 NDMA 低于单氯胺化过程中的 NDMA 生成量。在两步氯化过程中，在某些预加氯剂量（例如 Cl/N 摩尔比为 20 或 4）下，NDMA 的生成得到增强。预加氯剂量改变了 Cl/N 比，随着比的增加，总余氯得以形成并减少。当该比值较高时，可能发生了折点氯化，从而增强了 NDMA 的生成。尽管两步氯化成功地抑制了 NDMA 的生成，但铵使这些药物的 NDMA 生成量恢复到在氯胺化过程中观察到的范围，这表明在两步氯化过程中控制铵对于限制药物中亚硝胺的形成非常重要。
