硝基苯酚化合物(NCs)在水环境中分布广泛,被认为是重要的消毒副产物(DBPs)前体。在这里,选择4-硝基苯酚和2-氨基-4-硝基苯酚作为代表性NC,以探索UV/后氯化过程中氯化DBPs(Cl-DBPs)的形成。二氯硝基甲烷(DCNM),三氯硝基苯甲烷(TCNM),二氯乙腈(DCAN),和三氯甲烷(TCM)由4-硝基苯酚和2-氨基-4-硝基苯酚在UV/后氯化过程中形成,2-氨基-4-硝基苯酚的单个Cl-DBPs的产率高于4-硝基苯酚的产率。同时,增加氯接触时间,UV注量,游离氯剂量可以增强Cl-DBPs的形成,而这三个因素中更高的值可能会降低Cl-DBPs的产率。此外,碱性pH可以降低卤代甲烷(HNMs)和DCAN的产量,但可以提高中药的产量。此外,较高浓度的4-硝基苯酚和2-氨基-4-硝基苯酚将诱导更多的Cl-DBPs形成。随后,DCNM可能的形成途径,TCNM,DCAN,根据转化产物(TP)和密度泛函理论(DFT)计算,提出了在UV/后氯化过程中TCM形成的4-硝基苯酚和2-氨基-4-硝基苯酚。值得注意的是,由2-氨基-4-硝基苯酚形成的Cl-DBPs比由4-硝基苯酚形成的Cl-DBPs具有更高的毒性。在这些生成的Cl-DBPs中,DCAN和TCNM具有较高的细胞毒性和遗传毒性,分别。此外,4-硝基苯酚,2-氨基-4-硝基苯酚,它们的TP表现出生态毒性。最后,4-硝基苯酚和2-氨基-4-硝基苯酚具有很高的生产DCNM的潜力,TCNM,DCAN,和TCM在紫外线/后氯化过程中的实际水域,但是Cl-DBPs的产量与模拟水域的明显不同。这项工作可以帮助更好地了解在UV/后氯化过程中不同NC的Cl-DBPs形成,并有助于控制Cl-DBPs的形成。
Nitrophenol compounds (NCs) are widely distributed in water environments and regarded as important precursors of disinfection byproducts (DBPs). Herein, 4-nitrophenol and 2-amino-4-nitrophenol were selected as representative NCs to explore chlorinated DBPs (Cl-DBPs) formation during UV/post-chlorination. Dichloronitromethane (DCNM), trichloronitromethane (TCNM), dichloroacetonitrile (DCAN), and trichloromethane (TCM) were formed from 4-nitrophenol and 2-amino-4-nitrophenol during UV/post-chlorination, and the yields of individual Cl-DBPs from 2-amino-4-nitrophenol were higher than those from 4-nitrophenol. Meantime, increasing chlorine contact time, UV fluence, and free chlorine dose could enhance Cl-DBPs formation, while much higher values of the three factors might decrease the yields of Cl-DBPs. Besides, alkaline pH could decrease the yields of halonitromethane (HNMs) and DCAN but increase the yields of TCM. Also, higher concentrations of 4-nitrophenol and 2-amino-4-nitrophenol would induce more Cl-DBPs formation. Subsequently, the possible formation pathways of DCNM, TCNM, DCAN, and TCM form 4-nitrophenol and 2-amino-4-nitrophenol during UV/post-chlorination were proposed according to transformation products (TPs) and density functional theory (DFT) calculation. Notably, Cl-DBPs formed from 2-amino-4-nitrophenol presented higher toxicity than those from 4-nitrophenol. Among these generated Cl-DBPs, DCAN and TCNM posed higher cytotoxicity and genotoxicity, respectively. Furthermore, 4-nitrophenol, 2-amino-4-nitrophenol, and their TPs exhibited ecotoxicity. Finally, 4-nitrophenol and 2-amino-4-nitrophenol presented a high potential to produce DCNM, TCNM, DCAN, and TCM in actual waters during UV/post-chlorination, but the Cl-DBPs yields were markedly different from those in simulated waters. This work can help better understand Cl-DBPs formation from different NCs during UV/post-chlorination and is conducive to controlling Cl-DBPs formation.