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Yu R, Qian Y, Chen Y, Shi Y, Guo J, An D. Computational-aided analysis of the pathway and mechanism of dichloroacetonitrile formation from phenylalanine upon chloramination. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 926:171995. [PMID: 38547977 DOI: 10.1016/j.scitotenv.2024.171995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/24/2024] [Accepted: 03/24/2024] [Indexed: 04/05/2024]
Abstract
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.
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Affiliation(s)
- Rui Yu
- Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, PR China
| | - Yunkun Qian
- Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, PR China.
| | - Yanan Chen
- Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, PR China
| | - Yijun Shi
- Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, PR China
| | - Jun Guo
- Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, PR China
| | - Dong An
- Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
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Detection and Stability of Cyanogen Bromide and Cyanogen Iodide in Drinking Water. WATER 2022. [DOI: 10.3390/w14101662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study systematically summarized the factors affecting the stability of CNXs, providing a reference for better control and elimination of CNXs. A method for the detection of CNBr and CNI in solution was established using a liquid–liquid extraction/gas chromatography/electron capture detector. Specifically, the method was used to investigate the stability of CNBr and CNI in drinking water, especially in the presence of chlorine and sulfite, and it showed good reproducibility (relative standard deviation <3.05%), high sensitivity (method detection limit <100 ng/L), and good recovery (91.49–107.24%). Degradation kinetic studies of cyanogen halides were conducted, and their degradation rate constants were detected for their hydrolysis, chlorination, and sulfite reduction. For hydrolysis, upon increasing pH from 9.0 to 11.0, the rate constants of CNCl, CNBr, and CNI changed from 8 to 155 × 10−5 s−1, 1.1 to 34.2 × 10−5 s−1, and 1.5 to 6.2 × 10−5 s−1, respectively. In the presence of 1.0 mg/L chlorine, upon increasing pH from 7.0 to 10.0, the rate constants of CNCl, CNBr, and CNI changed from 36 to 105 × 10−5 s−1, 15.8 to 49.0 × 10−5 s−1, and 1.2 to 24.2 × 10−5 s−1, respectively. In the presence of 3 μmol/L sulfite, CNBr and CNI degraded in two phases. In the first phase, they degraded very quickly after the addition of sulfite, whereas, in the second phase, they degraded slowly with rate constants similar to those for hydrolysis. Owing to the electron-withdrawing ability of halogen atoms and the nucleophilic ability of reactive groups such as OH− and ClO−, the rate constants of cyanogen halides increased with increasing pH, and they decreased in the order of CNCl > CNBr > CNI during hydrolysis and chlorination. The hydrolysis and chlorination results could be used to assess the stability of cyanogen halides in water storage and distribution systems. The sulfite reduction results indicate that quenching residual oxidants with excess sulfite could underestimate the levels of cyanogen halides, especially for CNBr and CNI.
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Craven CB, Tang Y, Carroll K, An L, Chen B, Li XF. Closing the Gap of Known and Unknown Halogenated Nitrogenous Disinfection Byproducts in Water: Advanced Mass Spectrometry Techniques. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Cai L, Yu S, Li L. Formation of odorous aldehydes, nitriles and N-chloroaldimines from free and combined leucine during chloramination. WATER RESEARCH 2022; 210:117990. [PMID: 34974344 DOI: 10.1016/j.watres.2021.117990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 12/15/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Amino acids (AAs) are a major group of odorous disinfection by-product (O-DBP) precursors. O-DBPs formations during free chlorine disinfection has been previously investigated. However, knowledge regarding the O-DBP formation mechanism and kinetics under chloramination of AAs is very limited. In this study, the generation of odorous isovaleraldehyde, isovaleronitrile and N-chloroisovaleraldimine from leucine (Leu), a typical and abundant AA in many drinking water sources, in its free and combined forms during chloramination under several typical addition schemes of disinfectants was investigated. Free Leu and glycylleucine (Gly-Leu) were chosen as model compounds since they have been indicated to be O-DBP precursors during chlorination. Intermediate product analysis and kinetics studies were conducted to study the reaction mechanisms. Impacts of disinfectants dosages and pH were also investigated in experiments and simulations. The results indicated that comparing with chlorination, chloramination of Leu has its uniqueness by participating in reacting with isovaleraldehyde to form N-chloroisovaleraldimine. And all the three O-DBPs formations from free Leu and Gly-Leu during chloramination (with preformed NH2Cl) were less than those during chlorination, indicating that using NH2Cl for disinfection ensures control over the off-flavor problems to some degree. When chloramination was realized by adding chlorine and ammonia separately, a longer pre-chlorination time led to greater yields of the O-DBPs from both precursors, whereas adding ammonia before chlorine promoted more isovaleraldehyde formation from free Leu. Under alkaline conditions, more isovaleronitrile and N-chloroisovaleraldimine were produced, and acidic conditions led to more isovaleraldehyde formation during chloramination. Notably, O-DBPs yields from free Leu were approximately 1000 times greater than those from Gly-Leu during chloramination under all the schemes. In addition, chlor(am)ination experiments with real water from Taihu Lake (the third largest freshwater lake and water source for twenty million people in China) indicated the formation of N-chloroisovaleraldimine and isovaleraldehyde was highly likely to cause odorous problems in drinking water. This study facilitates further understanding of the causes of off-flavor issues in drinking water and can help control the odorous problems by optimizing the operating parameters of drinking water treatment plants.
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Affiliation(s)
- Luyang Cai
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Shuili Yu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Lei Li
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
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Affiliation(s)
- Susan D Richardson
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29205, United States
| | - Thomas A Ternes
- Federal Institute of Hydrology, Am Mainzer Tor 1, Koblenz 56068, Germany
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Soh YNA, Kunacheva C, Menon S, Webster RD, Stuckey DC. Comparison of soluble microbial product (SMP) production in full-scale anaerobic/aerobic industrial wastewater treatment and a laboratory based synthetic feed anaerobic membrane system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 754:142173. [PMID: 32920408 DOI: 10.1016/j.scitotenv.2020.142173] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 08/15/2020] [Accepted: 09/01/2020] [Indexed: 06/11/2023]
Abstract
This study focused on the characterisation of soluble microbial products (SMPs) produced from a full-scale multi-stage (anaerobic/aerobic) industrial wastewater treatment plant, and contrasted them to the SMPs detected in the effluent of a lab-scale AnMBR treating synthetic wastewater to determine if there were any common solutes detected irrespective of the feed organics. Recently developed analytical methods using gas chromatography coupled mass spectrometry (GC-MS) and liquid chromatography coupled quadrupole-time-of-flight (LC-Q-ToF) for SMP characterisation in a wide molecular weight (MW) range of 30-2000 Da (Da) were applied. Samples collected from the Industrial Wastewater plant were the upflow anaerobic sludge blanket (UASB) influent and effluent, and aerobic membrane bioreactor (MBR) effluent before discharge. The GC-MS detected a spike in cyclooctasulphur in the UASB effluent, an indicator of shock-loading, which disappeared after the MBR process. Alkanes, acids and nitrogenous compounds were found to be the end-products from the GC-MS results, while LC-Q-ToF analysis revealed that eicosanoids, a group of cell-signalling molecules, were produced in the aerobic MBR, and made up 71% of its effluent. A comparison of the submerged anaerobic membrane bioreactor (SAMBR) and aerobic MBR effluents using GC-MS showed that there was only a small degree of similarity between the SMPs, comprising mainly long chain alkanes and phthalate. On the other hand, LC-Q-ToF showed a large contrast in compound composition, mostly having cell-signalling functions, which deepened our understanding of the different metabolic processes occurring in aerobic and anaerobic systems. These data could be useful for future work in various areas such as controlling quorum-sensing and biofilm formation, process optimisation and control, and microbial ecology.
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Affiliation(s)
- Yan Ni Annie Soh
- Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; Interdisciplinary Graduate Programme, Graduate College, Nanyang Technological University, 61 Nanyang Drive, Academic Block North, ABN-01b-11, Singapore 637335, Singapore.
| | - Chinagarn Kunacheva
- Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore
| | - Suren Menon
- Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore
| | - Richard D Webster
- Division of Chemistry and Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - David C Stuckey
- Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK.
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Shao KL, Ye ZX, Huang H, Yang X. ClO 2 pre-oxidation impacts the formation and nitrogen origins of dichloroacetonitrile and dichloroacetamide during subsequent chloramination. WATER RESEARCH 2020; 186:116313. [PMID: 32841932 DOI: 10.1016/j.watres.2020.116313] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 07/11/2020] [Accepted: 08/17/2020] [Indexed: 05/23/2023]
Abstract
Chlorine dioxide (ClO2) can be used as a pre-oxidant when chloramination is performed in water treatment plants. However, the effects of ClO2 pre-oxidation on the formation of nitrogenous disinfection by-products, such as dichloroacetonitrile (DCAN) and dichloroacetamide (DCAcAm), during chloramination are not well understood. In this study, the effects of ClO2 pre-oxidation on the formation of DCAN and DCAcAm during chloramination of 28 model compounds and seven real water samples were investigated. The sources of nitrogen for DCAN and DCAcAm formation were investigated using 15N-labeled monochloramine. ClO2 pre-oxidation affected DCAN and DCAcAm formation during chloramination of model compounds in different ways. ClO2 pre-oxidation increased unlabeled and 15N-labeled DCAN and DCAcAm formation during chloramination of six amino acids and peptides and five indoles and tertiary amines. ClO2 pre-oxidation decreased DCAN formation but increased DCAcAm formation during chloramination of three hydroxybenzamide compounds, but had the opposite effects for four tetracyclines. ClO2 pre-oxidation generally decreased DCAN and DCAcAm formation during chloramination of the phenolic compounds that are precursors not containing nitrogen. 2-Aminoacetophenone, formamid-trans-muconic acid, and unsaturated ketones were found to be transformation products of ClO2 oxidation of 3-methylindole, salicylamide, and resorcinol, respectively. Possible DCAN and DCAcAm formation pathways during chloramination after ClO2 oxidation were identified. For most of the water samples, ClO2 pre-oxidation decreased the amounts of DCAN and DCAcAm formed during chloramination by 36%-70% and 11%-59%, respectively. This may have been caused by ClO2 oxidation destroying phenolic precursors and macromolecular proteins rather than amino acids in the water samples.
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Affiliation(s)
- Kai-Li Shao
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, P.R. China
| | - Zhao-Xi Ye
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, P.R. China
| | - Huang Huang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, P.R. China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, Guangdong, P.R. China.
| | - Xin Yang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, P.R. China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, Guangdong, P.R. China
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