School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, China; State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
J Environ Sci (China). 2017 Aug;58:116-126. doi: 10.1016/j.jes.2017.05.028. Epub 2017 May 28.
N-nitrosodimethylamine (NDMA) is an emerging disinfection by-product which is formed during water disinfection in the presence of amine-based precursors. Ranitidine, as one kind of amine-based pharmaceuticals, has been identified as NDMA precursor with high NDMA molar conversion during chloramination. This study focused on the characterization of NDMA formation during ozonation of ranitidine. Influences of operational variables (ozone dose, pH value) and water matrix on NDMA generation as well as ranitidine degradation were evaluated. The results indicate high reactivity of ranitidine with ozone. Dimethylamine (DMA) and NDMA were generated due to ranitidine oxidation. High pH value caused more NDMA accumulation. NDMA formation was inhibited under acid conditions (pH≤5) mainly due to the protonation of amines. Water matrix such as HCO and humic acid impacted NDMA generation due to OH scavenging. Compared with OH, ozone molecules dominated the productions of DMA and NDMA. However, OH was a critical factor in NDMA degradation. Transformation products of ranitidine during ozonation were identified using gas chromatography-mass spectrometry. Among these products, just DMA and N,N-dimethylformamide could contribute to NDMA formation due to the DMA group in the molecular structures. The NDMA formation pathway from ranitidine ozonation was also proposed.
N-亚硝基二甲胺（NDMA）是一种新兴的消毒副产物，在存在胺基前体的情况下，在水中消毒过程中形成。雷尼替丁作为一种胺基药物，已被确定为氯胺化过程中具有高 NDMA 摩尔转化率的 NDMA 前体。本研究侧重于研究雷尼替丁臭氧化过程中 NDMA 的形成特性。评估了操作变量（臭氧剂量、pH 值）和水基质对 NDMA 生成和雷尼替丁降解的影响。结果表明，雷尼替丁与臭氧具有很高的反应性。由于雷尼替丁的氧化，生成了二甲胺（DMA）和 NDMA。高 pH 值导致更多的 NDMA 积累。在酸性条件下（pH≤5），由于胺的质子化，NDMA 的形成受到抑制。水基质如 HCO 和腐殖酸由于 OH 捕获而影响 NDMA 的生成。与 OH 相比，臭氧分子在 DMA 和 NDMA 的生成中占主导地位。然而，OH 是 NDMA 降解的关键因素。使用气相色谱-质谱法鉴定了臭氧化过程中雷尼替丁的转化产物。在这些产物中，只有 DMA 和 N，N-二甲基甲酰胺由于分子结构中的 DMA 基团而能够导致 NDMA 的形成。还提出了雷尼替丁臭氧化生成 NDMA 的途径。
