College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China; Zhejiang Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology, Hangzhou 310023, China.
College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China.
Sci Total Environ. 2023 Oct 10;894:164847. doi: 10.1016/j.scitotenv.2023.164847. Epub 2023 Jun 16.
This study systematically compared the degradation kinetics, conversion pathways, formation of disinfection by-products (DBPs), and changes in toxicity for sulfamethazine and carbamazepine in UV/nitrate system. Additionally, the study simulated the generation of DBPs in the post-chlorination process after the introduction of bromine ions (Br). The contributions of UV irradiation, hydroxyl radicals (OH), and reactive nitrogen species (RNS) to SMT degradation were determined to be 28.70 %, 11.70 %, and 59.60 %, respectively. The contributions of UV irradiation, OH, and RNS to CBZ degradation were found to be 0.00 %, 96.90 %, and 3.10 %, respectively. A higher dosage of NO facilitated the degradation of both SMT and CBZ. Solution pH posed almost no effect on SMT degradation, while acidic conditions favored CBZ removal. The degradation of SMT was found to be slightly promoted at low concentrations of Cl, while the presence of HCO significantly accelerated the degradation. Cl, as well as HCO, retarded the CBZ degradation. Natural organic matter (NOM) as a free radical scavenger and UV irradiation filter posed a substantial inhibitory effect on the degradation of SMT and CBZ. The degradation intermediates and transformation pathways of SMT and CBZ by UV/NO system were further elucidated. The results showed that the main reaction pathways were bond-breaking reaction, hydroxylation, and nitration/nitrosation reaction. The acute toxicity of most of the intermediates generated during SMT and CBZ degradation was reduced after UV/NO treatment. After treatment of SMT and CBZ in UV/nitrate system, the DBPs generated in subsequent chlorination were mainly trichloromethane and a small amount of nitrogen-containing DBPs. After bromine ions were introduced in UV/NO system, a large amount of the originally generated trichloromethane was converted to tribromomethane.
本研究系统比较了磺胺甲恶唑和卡马西平在 UV/硝酸盐体系中的降解动力学、转化途径、消毒副产物（DBPs）的形成以及毒性变化。此外，该研究还模拟了引入溴离子（Br）后在后氯化过程中 DBPs 的生成。确定 UV 辐射、羟基自由基（OH）和活性氮物种（RNS）对 SMT 降解的贡献分别为 28.70%、11.70%和 59.60%。UV 辐射、OH 和 RNS 对 CBZ 降解的贡献分别为 0.00%、96.90%和 3.10%。较高剂量的 NO 有利于 SMT 和 CBZ 的降解。溶液 pH 值对 SMT 降解几乎没有影响，而酸性条件有利于 CBZ 的去除。发现 SMT 的降解在 Cl 浓度较低时略有促进，而 HCO 的存在则显著加速了降解。Cl 和 HCO 均会延迟 CBZ 的降解。天然有机物（NOM）作为自由基清除剂和 UV 辐射过滤器，对 SMT 和 CBZ 的降解具有显著的抑制作用。进一步阐明了 UV/NO 体系中 SMT 和 CBZ 的降解中间产物和转化途径。结果表明，主要反应途径是键断裂反应、羟化反应和硝化/亚硝化反应。UV/NO 处理后，SMT 和 CBZ 降解过程中生成的大多数中间体的急性毒性降低。在 UV/硝酸盐体系中处理 SMT 和 CBZ 后，随后氯化生成的 DBPs 主要为三氯甲烷和少量含氮 DBPs。在 UV/NO 体系中引入溴离子后，大量原本生成的三氯甲烷转化为三溴甲烷。
