Department of Municipal Engineering, Southeast University, Nanjing, 211189, China.
Department of Municipal Engineering, Southeast University, Nanjing, 211189, China.
Chemosphere. 2022 Mar;291(Pt 1):132731. doi: 10.1016/j.chemosphere.2021.132731. Epub 2021 Oct 28.
Halonitromethanes (HNMs) is a typical class of nitrogenous disinfection byproducts with high toxicity. The effect of Br on the formation and transformation of HNMs from dimethylamine (DMA) during the ultraviolet (UV)/chlorine disinfection has been investigated in current study. Results reveal that only chloronitromethane, dichloronitromethane and trichloronitromethane (TCNM) could be found during the UV/chlorine disinfection. Whereas in the presence of Br, nine species of HNMs could be observed simultaneously. When Br concentration increased from 0 to 15.0 mg L, the predominant species of HNMs were gradually changed from TCNM to dibromonitromethane and tribromonitromethane, which contributed to 23.37% and 31.07% of total HNMs concentration at 15 mg L Br, respectively. The presence of Br not only shifted the chlorinated-HNMs (Cl-HNMs) towards brominated-HNMs (Br-HNMs) but also affected the dominant species and total concentration of HNMs. When Br concentration was 4.0 mg L, the formation of HNMs decreased with the increase of pH from 6.0 to 8.0 and increased with the increase of free chlorine and DMA. When free chlorine concentration rose from 0.25 to 1.1 mmol L, Br-HNMs were shifted to Br(Cl)-HNMs and then to Cl-HNMs. According to the findings, possible formation and transformation pathways of HNMs from DMA were proposed in the presence of Br during the UV/chlorine disinfection. Finally, it was proved that the effect of Br on the trend of HNMs in real water was similar to that in deionized water, but higher HNMs concentrations and delayed peak time were observed in real water. This study can provide the scientific evidence and fundamental data for the applications of UV/chlorine disinfection in the treatment of water containing Br.
卤代硝基甲烷（HNMs）是一类具有高毒性的典型含氮消毒副产物。本研究考察了溴对 UV/氯消毒过程中二甲胺（DMA）生成和转化为 HNMs 的影响。结果表明，只有氯硝基甲烷、二氯硝基甲烷和三氯硝基甲烷（TCNM）可在 UV/氯消毒过程中被检测到。而在溴存在的情况下，可同时观察到九种 HNMs。当 Br 浓度从 0 增加到 15.0 mg/L 时，HNMs 的主要物种逐渐从 TCNM 转变为二溴硝基甲烷和三溴硝基甲烷，在 15 mg/L Br 时，这两种物质分别占 HNMs 总浓度的 23.37%和 31.07%。Br 的存在不仅使氯化-HNMs（Cl-HNMs）向溴化-HNMs（Br-HNMs）转移，而且还影响 HNMs 的主要物种和总浓度。当 Br 浓度为 4.0 mg/L 时，随着 pH 值从 6.0 增加到 8.0，HNMs 的生成量减少，而随着自由氯和 DMA 的增加而增加。当自由氯浓度从 0.25 增加到 1.1 mmol/L 时，Br-HNMs 转变为 Br(Cl)-HNMs，然后转变为 Cl-HNMs。根据研究结果，提出了在 UV/氯消毒过程中 Br 存在下，DMA 生成和转化为 HNMs 的可能途径。最后，证明了 Br 对 UV/氯消毒过程中 HNMs 趋势的影响在去离子水中与实际水中相似，但在实际水中观察到更高的 HNMs 浓度和延迟的峰值时间。本研究可为 UV/氯消毒在含 Br 水处理中的应用提供科学依据和基础数据。
