SCIENCE OF THE TOTAL ENVIRONMENT
·
2024
·
IF 8.2
Rui Yu,Yunkun Qian,Yanan Chen,Yijun Shi,Jun Guo,Dong An
Dichloroacetonitrile (DCAN) is an emerging disinfection by-product (DBP) that is widespread in drinking water. However, the pathway for DCAN formation from aromatic amino acids remains unclear, leading to a lack of an understanding of its explicit fate during chloramination. In this study, we investigated the specific formation mechanism of DCAN during the chloramination of phenylalanine based on reaction kinetics and chemical thermodynamics. The reason for differences between aldehyde and decarboxylation pathways was explained, and kinetic parameters of the pathways were obtained through quantum chemistry calculations. The results showed that the reaction rate constant of the rate-limiting step of the aldehyde pathway with 1.9 × 10 −11 s −1 was significantly higher than that of decarboxylation (3.6 × 10 −16 s −1 M −1 ), suggesting that the aldehyde pathway is the main reaction pathway for DCAN formation during the chloramination of phenylalanine to produce DCAN. Subsequently, theoretical calculations were performed to elucidate the effect of pH on the formation mechanism, which aligned well with the experimental results. Dehydrohalogenation was found to be the rate-limiting step under acidic conditions with reaction rate constants higher than those of the rate-limiting step (expulsion of amines) under neutral conditions, increasing the rate of DCAN formation. This study highlights the differences in DCAN formation between the decarboxylation and aldehyde pathways during the chloramination of precursors at both molecular and kinetic levels, contributing to a comprehensive understanding of the reaction mechanisms by which aromatic free amino acids generate DCAN.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ANALYST
·
2023
·Vol. 148
·期 21
·5390-5394
·
IF 4.2
Jiaben Zhong,Hangyan Zhang,Yina Cai,Xiuping Chen,Zhiyuan Fang,Dun Deng
Dichloroacetonitrile (DCAN) is a common biotoxic disinfection by-product (DBP) of chlorine. The current methods used for detecting DCAN are tedious and heavily instrument-dependent, and are not suitable for on-site detection. In the present study, we developed a colorimetric assay for rapid detection of DCAN. DCAN in water acted as a complexing agent that formed a complex with cuprous species. The cuprous species was then extracted by chloroform and visualized using dithizone. The visual detection limit for DCAN was 20 ng mL−1, while fluorescence quantification could detect DCAN at a concentration as low as 8.75 ng mL−1. Moreover, haloacetonitriles (HANs) derived from chlorine disinfection and structurally similar to DCAN, including TCAN, BCAN, and DBAN, could also be detected using this method. Other DBPs at concentrations as high as 200 ng mL−1 did not affect the detection process. The low cost and instrument-independence characteristic of the present method enables its routine determination of the concentration of DCAN in water.
研究领域:
环境科学
·
分析化学
·
毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
WATER RESEARCH
·
2024
·
IF 11.4
Jinxiu Lou,Lu Yin,Feilong Dong,Zhanfei He,Huijie Lu,Shuangxi Fang,Xiangliang Pan
Nitrogenous disinfection byproducts (N-DBPs) are notorious for their serious health risks, yet nitrate (NO 3 - ) mediates N-DBPs generation during UV/chlorine treatment remains unexplored. This study investigated the interaction of chlorine and NO 3 - on N-DBPs formation and developed a specific fragment-based screening method using UPLC-QTOF-MS to explore the underlying mechanism. Results showed that the chlorine-to-nitrogen (Cl/NO 3 - -N) molar ratio significantly affects dichloroacetonitrile (DCAN) and dichloroacetamide (DCAM) generation, with peak concentrations at a Cl/NO 3 - -N molar ratio of around 15. NO 3 - promotes the production of HO • , which positively correlates with DCAN and DCAM concentrations, also peaking at this ratio. Utilizing our developed method, three key hydroxyl-substituted intermediates that circumvent the previously reported “limiting-steps” in DCAN formation were identified. This reaction proceeds via a stepwise mechanism involving hydroxylation and chlorine substitution to produce hydroxyl-phenylacetonitrile and hydroxyl-chlorine-phenylacetonitrile. The conversion rate of hydroxyl-chlorine-phenylacetonitrile to DCAN was 8.6 times higher at Cl/NO 3 - -N molar ratio of 15 compared to conditions without NO 3 - , attributed to the weakened bond strength of the side chain, as supported by density functional theory calculations. This study provides novel insights into the mechanistic pathways of DCAN and DCAM formation, critical for developing more effective drinking water disinfection technologies to control N-DBPs.
研究领域:
环境科学
·
饮用水处理
·
化学动力学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Zhiwei Zhao,Yu Li,Fei Wang,Zhitao Xu,Sai Zhang,Li Li,Junyu Fan,Jie Liu
Monitoring and regulating the formation of toxic byproducts in advanced oxidation processes (AOPs) is of great significance for their practical application in water treatment. In this work, we found that dichloroacetonitrile (DCAN), a common N-containing byproduct in chloramination disinfection, can be formed with the co-presence of g-C 3 N 4 and chloride in a peroxymonosulfate (PMS) system. The measured value was 12.01 μM within 12 h under the given conditions. Structure analysis of raw and used g-C 3 N 4 demonstrated that g-C 3 N 4 decomposition indeed occurred, and C = N bonds acted as primary active sites, releasing N resources for subsequent DCAN formation. Additionally, multiple parameters, including the reactant (i.e., g-C 3 N 4 , PMS, Cl - , phenol) dose and solution pH, were observed to remarkably affect the yield of DCAN. Phenol was identified as the organic precursor of DCAN and may cooperate with inorganic chloramine to promote DCAN formation via the decarboxylation pathway. This study highlights the generation of DCAN in N-involved catalyst-based AOPs and improves understanding of the DCAN formation mechanism.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 59
·33681-33687
·
IF 2.936
Xing Zhang,Jilun Yao,Wei Peng,Wensi Xu,Zhongguo Li,Chong Zhou,Zhendong Fang
Response surface methodology (RSM) was utilized to model and optimize the dichloroacetonitrile (DCAN) degradation process by UV/PMS. A quadratic function between DCAN degradation efficiency and three factors including dosage of PMS, UV power and retention time was obtained. The model fitted very well according to high the value of R2 (0.9919) and Adj-R2 (0.9814). Additionally, the analysis of variance showed the influence of factors on degradation efficiency followed: retention time > UV power > dosage of PMS. Finally, the optimum conditions were suggested under this model. The degradation efficiency reached the maximum value of 96.2% with the optimum conditions: dosage of PMS = 0.2 mM, UV power = 7.95 W, retention time = 80 min.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2021
·
IF 7.963
Si-Yu Duan,Xue Chen,Huang Huang,Xin Yang,Xin Lu
The formation of nitrogenous disinfection byproducts (N-DBPs) occurs in chloraminated water in drinking water distribution systems and may be affected by metal pipe materials and their corrosion products. The effect of copper corrosion products, including Cu 2+ , CuO, and Cu 2 O, on the formation of dichloroacetonitrile (DCAN) and dichloroacetamide (DCAcAm) was investigated during chloramination of natural organic matter (NOM), model precursors (carboxylic acids and amino acids), and real water samples. Copper corrosion products enhanced DCAN and DCAcAm formation during chloramination of NOM by 33%–72% and 11%–80%, respectively. Addition of 15 N-labeled monochloramine showed that the copper corrosion products primarily enhanced the formation of DCAN using organic nitrogen and monochloramine as nitrogen sources, and the formation of DCAcAm using monochloramine as the nitrogen source, but had a limited impact on the formation of DCAcAm using organic nitrogen as the nitrogen source. A distinct N-DBP formation pathway in the presence of Cu 2+ and CuO was observed using tyrosine as a model compound, which included the formation of 1,4-benzoquinone as a dominant intermediate. On reaction with monochloramine, the 1,4-benzoquinone greatly contributed to enhancement of DCAN and DCAcAm formation using monochloramine as the nitrogen source. During chloramination of real water samples, Cu 2+ and CuO enhanced DCAN formation by 9–40% and DCAcAm formation by 16–33%. This study increases our knowledge of copper catalyzed DCAN and DCAcAm formation in copper pipes, which will be meaningful for water safety in distribution systems using chloramine disinfection.
研究领域:
环境科学
·
公共卫生
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Baoqiang Hao,Yang Guo,Xueling Bai,Renyuan Zhang,Xiaoqing Li,Jing Li
The combined application of chlorination and UV irradiation has the potential to yield important benefits in water treatment. However, much of the fundamental chemistry that governs the behavior of UV/chlorine systems have not been well defined. Cyano-containing pesticides (CNPs) are widely used in agriculture and inevitably enter surface waters and other aquatic environments. In this study, twenty CNPs and their intermediates were investigated to evaluate the formation of disinfection byproducts under chlorination and UV/chlorine systems. It was found that UV/chlorine can significantly enhance the generation of cyanogen chloride (CNCl) and dichloroacetonitrile (DCAN) compared to chlorination alone. The CNCl and DCAN concentrations increased from an average of 0.13 and 0.12 μM during the chlorination alone to 0.85 and 0.41 μM, respectively, when UV 254 light was introduced. The maximum yields of CNCl and DCAN could reach 31.8 % and 7.7 %, respectively. Both the photo-induced • OH and • Cl played a key role in the generation of CNCl and DCAN. Additionally, higher yields of total CNX were observed in the UV/chlorine system in the presence of bromide. Similar results were obtained in the treatment of actual water samples, in which the concentrations of CNCl and DCAN increased by orders of magnitude under UV/chlorine treatment compared to the chlorination alone. The results showed that the cyano group of organic pollutants has a higher potential to be directly converted to toxic CNCl and DCAN under UV/chlorine treatment. The inclusion of this basic chemistry will deepen our understanding of UV/chorine water treatment technologies.
研究领域:
环境科学
·
水处理化学
·
毒理学
✓ 已验证
产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2024
·
IF 8.2
Jinfeng He,Hongyan Liu,Zemeng Li,Minhua Xu,Yong Zhang,Tiemin Jiang,Lingyun Mo
Dichloroacetonitrile (DCAN), an emerged nitrogenous disinfection by-product (N-DBP) in drinking water, has garnered attention owing to its strong cytotoxicity, genotoxicity, and carcinogenicity. However, there are limited studies on its potential hepatotoxicity mechanisms. Understanding hepatotoxicity is essential in order to identify and assess the potential risks posed by environmental pollutants on liver health and to safeguard public health. Here, we investigated the viability, reactive oxygen species (ROS) levels, and cell cycle profile of DCAN-exposed HepG2 cells and analyzed the mechanism of DCAN-induced hepatotoxicity using both transcriptomic and metabolomic techniques. The study revealed that there was a decrease in cell viability, increase in ROS production, and increase in the number of cells in the G2/M phase with an increase in the concentration of DCAN. Omics analyses showed that DCAN exposure increased cellular ROS levels, leading to oxidative damage in hepatocytes, which further induced DNA damage, cell cycle arrest, and cell growth impairment. Thus, DCAN has significant toxic effects on hepatocytes. Integrated analysis of transcriptomics and metabolomics offers new insights into the mechanisms of DCAN-induced hepatoxicity.
研究领域:
毒理学
·
分子生物学
·
环境科学
·
公共卫生
✓ 已验证
DOI
PubMed
高影响因子
ENVIRONMENTAL POLLUTION
·
2024
·
IF 7.6
Fangyuan Peng,Yingyang Wang,Yi Lu,Zhaoguang Yang,Haipu Li
The increasing demand for trichloroisocyanuric acid (TCCA) in swimming pool disinfection highlights the need to evaluate its applicability in terms of disinfection by-product (DBP) formation. Nevertheless, there is limited understanding of DBP formation and control during TCCA disinfection, particularly concerning the effects of various management parameters. This study aimed to fill this knowledge gap by comprehensively investigating DBP formation during TCCA chlorination, with a particular focus on assessing the contribution and interaction of influencing factors using Box-Behnken Design and response surface methodology. Results indicated that the concentrations of trichloroacetaldehyde, chloroform, dichloroacetic acid, trichloroacetic acid, and dichloroacetonitrile produced by TCCA disinfectant were 42.5%, 74.0%, 48.1%, 94.7% and 42.6% of those by the conventional sodium hypochlorite disinfectant, respectively. Temperature exhibited the most significant impact on chloroform formation (49%), while pH played a major role in trichloroacetaldehyde formation (44%). pH 2 emerged as the primary contributor to dichloroacetic acid (90%) and trichloroacetic acid (93%) formation. The optimum water quality conditions were determined based on the minimum total DBPs (pH = 7.32, Temperature = 23.7 °C, [Cl − ] = 437 mg/L). Chlorine dosage and contact time exhibited greater influence than precursor concentration on chloroform, dichloroacetonitrile, trichloroacetaldehyde, trichloroacetic acid, and total DBPs. Although the interaction between water quality parameters was weak, the interaction between disinfection operating parameters demonstrated substantial effects on DBP formation (8.56–19.06%). Furthermore, the DBP predictive models during TCCA disinfection were provided for the first time, which provides valuable insights for DBP control and early warning programs.
研究领域:
环境科学
·
水处理
·
化学工程
·
公共卫生
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2023
·
IF 11.4
Yingying Zhou,Jia-jia Jiao,Huang Huang,Yong Dong Liu,Rugang Zhong,Xin Yang
Dichloroacetonitrile (DCAN) as one of the potentially prioritized regulated DBPs has drawn great attention; however, understanding its formation, especially the C–C bond cleavage mechanisms, is limited. In this study, DCAN formation mechanisms from long-chain primary amines, amino acids, and dipeptides during chlorination were investigated by a combined computational and experimental approach. The results indicate that nitriles initially generate for all of the above precursors, then they undergo β-C-hydroxylation or/and α-C-chlorination processes, and finally, DCAN is produced through the Cα–Cβ bond cleavage. For the first time, the underlying mechanism of the C–C bond cleavage was unraveled to be electron transfer from the O– anion into its attached C atom in the chlorinated nitriles, leading to the strongly polarized Cα–Cβ bond heterocleavage and DCAN– formation. Moreover, DCAN molar yields of precursors studied in the present work were found to be determined by their groups at the γ-site of the amino group, where the carbonyl group including −CO2–, −COR, and −CONHR, the aromatic group, and the −OH group can all dramatically facilitate DCAN formation by skipping over or promoting the time-consuming β-C-hydroxylation process and featuring relatively lower activation free energies in the C–C bond cleavage. Importantly, 4-amino-2-hydroxybutyric acid was revealed to possess the highest DCAN yield among all the known aliphatic long-chain precursors to date during chlorination. Additionally, enonitriles, (chloro-)isocyanates, and nitriles can be generated during DCAN formation and should be of concern due to their high toxicities.
研究领域:
环境化学
·
水处理
·
毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2021
·
IF 7.963
Han Chen,Tao Lin,Xiaoshu Yan,Hang Xu
The formation of haloacetonitriles (HANs) during chlorination after sulfite/ultraviolet (UV) treatment of bromate (BrO 3 − ) in the presence of amino acids (AAs) was investigated. During sulfite/UV treatment, the primary species hydrated electrons (e aq − ) and hydrogen atom radicals (H ) dominated the reduction of BrO 3 − to bromide (Br − ), whereas the sulfite anion radicals (SO 3 − ) and H degraded AAs to produce the intermediates HN=C(CH 3 )–COOH, CH 3 –CH=NH, and CH 3 –C≡N via α‑hydrogen abstraction and NH 2 –hydrogen abstraction mechanisms. During post-chlorination, Br − was converted to HBrO/BrO-, and the HN=C(CH 3 )–COOH, CH 3 –CH=NH, and CH 3 –C≡N groups featured higher bromine utilization factor (BUF) and chlorine utilization factor (CUF) values than AAs, enhancing the formation of dibromoacetonitrile (DBAN) and dichloroacetonitrile (DCAN). The energetic feasibility of the transformation pathway, that is, HN=C(CH 3 )–COOH, CH 3 –CH=NH, and CH 3 –C ≡ N formation via hydrogen abstraction by SO 3 − and H and their further conversion to HANs, was proved by density functional theory calculations, which showed stepwise negative Gibbs free energy changes (ΔG < 0). The effects of pH and water matrices (e.g., HCO 3 − , Cl − , Fe 3+ , and natural organic matter) were comprehensively evaluated. Although 72% of BrO 3 − was removed by sulfite/UV treatment in the presence of AAs, the cytotoxicity index (CTI) and genotoxicity index (GTI) during post-chlorination increased by 213% and 125%, respectively, due to the formation of 24 CX 3 R-type disinfection by-products (DBPs), especially brominated DBPs. Accordingly, more attention should be given to the formation of brominated DBPs during post-chlorination when using sulfite/UV processes to remove BrO 3 − in the presence of AAs. As a solution, using monochloramine instead of chlorine as a disinfectant after the sulfite/UV process could significantly lower the CTI and GTI values by alleviating the formation of brominated DBPs.
研究领域:
环境科学
·
水处理
·
化学工程
·
毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Guangcai Ma,Yifan Jin,Yujie Yu,Jiangmin Liu,Hui Shen,Xiaoxuan Wei,Haiying Yu
Understanding the molecular mechanisms behind the formation of unregulated nitrogenous disinfection by-products (N-DBPs), such as dichloroacetonitrile (DCAN) and dichloroacetamide (DCAcAm), during chloramination of various dissolved organic nitrogen compounds—particularly free amino acids (AAs)—is critical for elucidating their formation fate and mitigating their occurrence in treated water. This study offers computational and experimental insights into the formation potential and mechanisms of DCAN/DCAcAm from distinct precursors. The experiments reveal a clear trend in DCAN formation potential: Asparagine (Asn) > aspartic acid (Asp) > β -alanine ( β -Ala) ≈ 4 - amino-2-hydroxybutyric acid (AHBA) > > alanine (Ala), aligning well with computed reaction energetics. The computations highlight a novel “one-step chlorination + decarboxylation” mechanism that may kinetically dominate the formation of DCAN and its hydrolysate DCAcAm from Asp and Asn at low NH 2 Cl levels, while higher concentrations of NH 2 Cl promote DCAN formation via the “aldehyde” pathway. Notably, Asn chloramination preferentially generates DCAcAm via multistep transformation from an aldehyde-based intermediate, enhancing its overall yield. By contrast, both β -Ala and AHBA form DCAN via a two-step N -chlorination pathway, owing to the absence of C α −COO - . The application of 15 NH 2 Cl to Asp and Asn further confirms NH 2 Cl as the primary nitrogen donor for DCAN formation at high [NH 2 Cl]/[org-N] ratios, whereas β -CONH 2 in Asn predominantly contributes to DCAcAm nitrogen. Mechanistically, electron-withdrawing groups at the C α and C β sites of precursors synergistically activate the C α −C β bond, facilitating DCAN/DCAcAm formation. Accordingly, removing the precursors with R , R' -CH-NH 2 groups effectively reduces DCAN/DCAcAm levels during water chloramination disinfection.
研究领域:
环境化学
·
水处理
·
消毒副产物
·
计算化学
·
反应机理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）