Shenzhen Key Laboratory of Ecological Remediation and Carbon Sequestration, Environmental Protection Key Laboratory of Microorganism Application and Risk Control, Institute of Environment and Ecology, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, PR China; Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, PR China; Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Kyoto, 6158540, Japan.
Shenzhen Key Laboratory of Ecological Remediation and Carbon Sequestration, Environmental Protection Key Laboratory of Microorganism Application and Risk Control, Institute of Environment and Ecology, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, PR China; Pingshan District Urban Management and Law Enforcement Bureau, Shenzhen, 518118, PR China.
Environ Pollut. 2023 Dec 15;339:122771. doi: 10.1016/j.envpol.2023.122771. Epub 2023 Oct 17.
The ammonia/chlorine oxidation process can greatly degrade PPCPs in water. However, its effect on molecular transformations of natural organic matter (NOM) and effluent organic matter (EfOM) are still poorly understood. In this study, molecular transformations of NOM and EfOM occurring during ammonia/chlorine were explored and compared with those occurred during chlorination, using spectroscopy and mass spectrometry. Phenolic and highly unsaturated aliphatic compounds together with aliphatic compounds were found to be predominant in both NOM and EfOM samples, all of which were significantly degraded after two processes. The ammonia/chlorine process led to greater decreases in the molecular weights of such components but lower reductions in aromaticity. Compared with chlorination, ammonia/chlorine was found to be more likely to degrade compounds while remaining fluorophores or chromophores. The CH(N)O(S) precursors were found to be similar for both processes but their products were quite different. The CH(N)O(S) precursors that only found in ammonia/chlorine had higher molecular weights and greater degrees of oxidation but lower degrees of saturation. In contrast, the unique CH(N)O(S) products that only found in ammonia/chlorine exhibited lower molecular weights and lower degrees of oxidation degrees together with higher degrees of saturation. Lower total abundance of chlorinated byproducts was found by ammonia/chlorine compared with chlorination, although the former process provided a richer diversity. In all water samples, chlorinated byproducts were mainly generated by substitution reactions during ammonia/chlorine and chlorination. Overall, the findings of this study could provide new insights into the transformations of NOM and EfOM induced by ammonia/chlorine and chlorination.
氨/氯氧化过程可以极大地降解水中的 PPCPs。然而，其对天然有机物（NOM）和出水中有机物（EfOM）分子转化的影响仍知之甚少。在这项研究中，使用光谱和质谱法探讨了氨/氯过程中 NOM 和 EfOM 的分子转化，并将其与氯化过程中的转化进行了比较。发现酚类和高度不饱和脂肪族化合物以及脂肪族化合物是 NOM 和 EfOM 样品中的主要成分，这两种成分在两种处理过程后都明显降解。氨/氯过程导致这些成分的分子量下降更大，但芳香度降低较小。与氯化相比，氨/氯更有可能在保留荧光团或发色团的情况下降解化合物。发现两种过程的 CH(N)O(S)前体相似，但产物却大不相同。两种过程都存在的 CH(N)O(S)前体具有较高的分子量和较大的氧化程度，但较低的饱和度。相比之下，氨/氯中仅发现的独特 CH(N)O(S)产物具有较低的分子量和较低的氧化程度，同时具有较高的饱和度。与氯化相比，氨/氯产生的氯化副产物总量较低，尽管前者提供了更丰富的多样性。在所有水样中，氯化副产物主要通过氨/氯和氯化过程中的取代反应生成。总的来说，本研究的结果可以为氨/氯和氯化引起的 NOM 和 EfOM 转化提供新的见解。
