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Mao Y, Zhang W, Qi S, Yang H, Xie YF. Kinetics and mechanism of haloacetaldehyde formation from the reaction of acetaldehyde and chlorine. CHEMOSPHERE 2021; 283:131253. [PMID: 34157622 DOI: 10.1016/j.chemosphere.2021.131253] [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: 03/19/2021] [Revised: 06/11/2021] [Accepted: 06/15/2021] [Indexed: 06/13/2023]
Abstract
Haloacetaldehydes (HALs) are the third prevalent group of disinfection by-products (DBPs) by weight in drinking water, and their cytotoxicity and genotoxicity are higher than regulated DBPs. In order to understand their formation mechanism during chlorination and ozonation-chlorination, this study examined the reaction kinetics of chloral hydrate (CH), dichloroacetaldehyde (DCA), chloroacetaldehyde (CA) and acetaldehyde by chlorine at different pH values and chlorine doses. The results showed that the reaction rate constants increased with pH and chlorine dose, except that the degradation of CH would not be affected by the presence of free chlorine. At the same pH and chlorine dose, the half-lives of CH, DCA, CA and acetaldehyde were in the order of CH > acetaldehyde ≫ DCA > CA. A kinetic model used to predict the formation of HALs and chloroform during chlorination of acetaldehyde was developed, and the predicted data fitted well with the measured data. As pre-ozonation could oxidize natural organic matter to acetaldehydes, the concentration of acetaldehyde formed after pre-ozonation was used to calculate the HAL yields during ozonation-chlorination by the kinetic model, which fitted the experimental results well. The kinetic model elucidated that the formation mechanism of HALs was a stepwise substitution process on the α-hydrogen of acetaldehyde during chlorination.
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Affiliation(s)
- Yuqin Mao
- College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou, 310015, China
| | - Wen Zhang
- College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou, 310015, China
| | - Shengqi Qi
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China.
| | - Hongwei Yang
- Research Institute for Environmental Innovation (Suzhou), Tsinghua, Suzhou, 215163, China
| | - Yuefeng F Xie
- School of Environment, Tsinghua University, Beijing, 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA17057, USA
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Cao X, Zhao J, Wang Z, Xing B. New insight into the photo-transformation mechanisms of graphene oxide under UV-A, UV-B and UV-C lights. JOURNAL OF HAZARDOUS MATERIALS 2021; 403:123683. [PMID: 32846254 DOI: 10.1016/j.jhazmat.2020.123683] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 07/17/2020] [Accepted: 08/07/2020] [Indexed: 06/11/2023]
Abstract
Photo-transformation dominates the fate of graphene oxide (GO) in the environment. However, the photo-transformation mechanisms of GO under different UV bands remain unclear. Our results showed that UV bands played a crucial role in sunlight-induced GO transformation. UVA and UVB induced significant photo-reduction of GO as indicated by decreasing surface O/C ratio, which could be explained by an O2-independent electron-hole pair-mediated mechanism (Mechanism I), and an O2-dependent reactive oxygen species (ROS)-mediated reduction mechanism (Mechanism II). Mechanism II accounted for 62.7 % and 33.3 % of total GO photo-transformation under UVA and UVB, respectively. Different from UVA and UVB, UVC led to GO reduction under anaerobic condition via Mechanism I and Mechanism III (direct decarboxylation). However, under aerobic condition, UVC caused significant oxidation of GO, which was the combined effect of Mechanisms I-III and the oxidation of graphitic structure on GO with the assistance of O2 (Mechanism IV). Moreover, it was demonstrated that the environmental factors (e.g., dissolved organic matter, phosphate) significantly enhanced the photo-transformation of GO in natural water. The information in the present work is useful for better understanding the fate of GO in aquatic environments.
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Affiliation(s)
- Xuesong Cao
- Institute of Environmental Processes and Pollution control, and School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Jian Zhao
- Institute of Coastal Environmental Pollution Control, Ministry of Education Key Laboratory of Marine Environment and Ecology, and Institute for Advanced Ocean Study, Ocean University of China, Qingdao 266100, China.
| | - Zhenyu Wang
- Institute of Environmental Processes and Pollution control, and School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.
| | - Baoshan Xing
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
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Bibliometric review of research trends on disinfection by-products in drinking water during 1975–2018. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.116741] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Jia L, Liu W, Cao J, Wu Z, Yang C. Modified multi-walled carbon nanotubes assisted foam fractionation for effective removal of acid orange 7 from the dyestuff wastewater. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 262:110260. [PMID: 32090883 DOI: 10.1016/j.jenvman.2020.110260] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 02/09/2020] [Accepted: 02/10/2020] [Indexed: 06/10/2023]
Abstract
In this study, multi-walled carbon nanotubes (MWCNTs) had been used to strengthen the removal of acid orange 7 (AO7) from the dyestuff wastewater by using foam fractionation. First, the surface modification of MWCNTs was performed by introducing hypochlorite groups (-OCl). The modified MWCNTs were characterized by using SEM, XRD, FTIR and Raman spectroscopy. Subsequently, the potential of modified MWCNTs as a novel collector for AO7 adsorption was examined. The adsorption conditions of modified MWCNTs towards AO7 were optimized by using response surface methodology (RSM) with a central composite design (CCD). The adsorption capacity of modified MWCNTs towards AO7 could reach 47.72 ± 0.79 mg·g-1 under the optimum conditions. The kinetics and the equilibrium adsorption data were analyzed by using different kinetic and isotherm models. According to the regression results, adsorption kinetics data were well described by pseudo-second order model, whereas adsorption isotherm data were best represented by Langmuir isotherm model. Finally, foam fractionation was performed with a batch mode. Under the suitable conditions of loading liquid volume 300 mL, modified MWCNTs dosage 180 mg, cetyltrimethylammonium bromide (CTAB) concentration 50 mg·L-1, AO7 concentration 30 mg·L-1, pore diameter of gas distributor 0.125 mm and air flow rate 100 mL·min-1, the removal percentage and enrichment ratio of AO7 were 91.23% and 6.17, respectively. The decolourization ratio of solution after foam fractionation was found to be 98.66%.
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Affiliation(s)
- Lei Jia
- School of Chemical Engineering and Technology, Hebei University of Technology, No.8 Guangrong Road, Dingzi Gu, Hongqiao District, Tianjin, 300130, China
| | - Wei Liu
- School of Chemical Engineering and Technology, Hebei University of Technology, No.8 Guangrong Road, Dingzi Gu, Hongqiao District, Tianjin, 300130, China.
| | - Jilin Cao
- State Key Laboratory of Green Chemical Engineering and Efficient Energy Saving, School of Chemical Engineering, Hebei University of Technology, Tianjin, 300130, China.
| | - Zhaoliang Wu
- School of Chemical Engineering and Technology, Hebei University of Technology, No.8 Guangrong Road, Dingzi Gu, Hongqiao District, Tianjin, 300130, China
| | - Chunyan Yang
- School of Chemical Engineering and Technology, Hebei University of Technology, No.8 Guangrong Road, Dingzi Gu, Hongqiao District, Tianjin, 300130, China
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Effects of Pre-Oxidation on Haloacetonitrile and Trichloronitromethane Formation during Subsequent Chlorination of Nitrogenous Organic Compounds. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17031046. [PMID: 32045988 PMCID: PMC7038144 DOI: 10.3390/ijerph17031046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/20/2020] [Accepted: 02/01/2020] [Indexed: 11/17/2022]
Abstract
The reaction between organic matter and disinfectants leads to the formation of disinfection byproducts (DBPs) in drinking water. With the improvement of detection technology and in-depth research, more than 1000 kinds of DBPs have been detected in drinking water. Nitrogenous DBPs (N-DBPs) are more genotoxic and cytotoxic than the regulated DBPs. The main methods are enhanced coagulation, pretreatment, and depth technologies which based are on conventional technology. Amino acids (AAs) are widely found in surface waters and play an important role by providing precursors from which toxic nitrogenous disinfection by-products (N-DBPs) are generated in chlorinated drinking water. The formation of N-DBPs, including dichloroacetonitrile, trichloroacetonitrile, and trichloronitromethane (TCNM), was investigated by analyzing chlorinated water using ozone (OZ), permanganate (PM), and ferrate (Fe(VI)) pre-oxidation processes. This paper has considered the control of pre-oxidation over N-DBPs formation of AAs, OZ, PM, and Fe(VI) pre-oxidation reduced the haloacetonitrile formation in the downstream chlorination. PM pre-oxidation decreased the TCNM formation during the subsequent chlorination, while Fe(VI) pre-oxidation had no significant influence on the TCNM formation, and OZ pre-oxidation increased the formation. OZ pre-oxidation formed the lowest degree of bromine substitution during subsequent chlorination of aspartic acid in the presence of bromide. Among the three oxidants, PM pre-oxidation was expected to be the best choice for reducing the estimated genotoxicity and cytotoxicity of the sum of the measured haloacetonitriles (HANs) and TCNM without bromide. Fe(VI) pre-oxidation had the best performance in the presence of bromide.
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Pang SY, Duan JB, Zhou Y, Gao Y, Jiang J. Oxidation kinetics of anilines by aqueous permanganate and effects of manganese products: Comparison to phenols. CHEMOSPHERE 2019; 235:104-112. [PMID: 31255750 DOI: 10.1016/j.chemosphere.2019.06.156] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 06/20/2019] [Accepted: 06/21/2019] [Indexed: 06/09/2023]
Abstract
In this study, the potential applicability of potassium permanganate (Mn(VII)) for anilines elimination was systematically investigated firstly, with a focus on the effect of manganese intermediates on the kinetics of anilines versus phenols. It was found that Mn(VII) could fairly oxidize anilines, where the second-order rate constants (kMn(VII)) values for anilines always decreased as pH increased from 5 to 9. This interesting pH-dependency was successfully described by the kinetic models proposed in literature to account for the unusual pH-rate profiles for phenols, where the formation of intermediates between Mn(VII) and phenols or anilines was likely involved. The effect of manganese products such as MnO2 and Mn(III) on the oxidation of anilines by Mn(VII) was demonstrated. Under slightly acidic conditions, the reactions of Mn(VII) with anilines displayed autocatalysis, suggesting a similar catalytic role of MnO2 formed in situ as compared to phenols. Several ligands (e.g., pyrophosphate) inhibited the formation of MnO2 colloids and lowered the oxidation rates of anilines by Mn(VII) at acidic pH, while these ligands greatly accelerated the kinetics of phenols under similar conditions. The contrasting effects of ligands might be mainly attributed to the different reactivity of ligand-stabilized Mn(III) formed in situ toward anilines vs phenols. The complex effect of humic acid was highly dependent on solution pH, possible due to the dual role of humic acid that it could act as a reductant (competitively consuming Mn(VII) and phenoxy or aniline radical) as well as a ligand (stabilizing manganese intermediates such as Mn(III) species) to affect Mn(VII) reactions.
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Affiliation(s)
- Su-Yan Pang
- Key Laboratory of Songliao Aquatic Environment, Ministry of Education, School of Municipal and Environmental Engineering, Jilin Jianzhu University, Changchun, 130118, China; College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin, 150040, China
| | - Jie-Bin Duan
- Key Laboratory of Songliao Aquatic Environment, Ministry of Education, School of Municipal and Environmental Engineering, Jilin Jianzhu University, Changchun, 130118, China; College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin, 150040, China
| | - Yang Zhou
- Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou, 510006, China
| | - Yuan Gao
- Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou, 510006, China.
| | - Jin Jiang
- Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou, 510006, China
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Zhou X, Zhang K, Zhang T, Yang Y, Ye M, Pan R. Formation of odorant haloanisoles and variation of microorganisms during microbial O-methylation in annular reactors equipped with different coupon materials. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 679:1-11. [PMID: 31078770 DOI: 10.1016/j.scitotenv.2019.04.329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 04/03/2019] [Accepted: 04/22/2019] [Indexed: 06/09/2023]
Abstract
Taste and odor (T & O) issues in drinking water have become serious problems which cannot be ignored by customers. Several studies have confirmed that microbes in water can biotransform halophenols (HPs) to haloanisoles (HAs) with earthy and musty flavors via microbial O-methylation. In this paper, the formation of 2-chloroanisole (2-CA), 2,4-dichloroanisole (2,4-DCA), 2,4,6-trichloroanisole (2,4,6-TCA), 2,3,6-trichloroanisole (2,3,6-TCA) and 2,4,6-tribromoanisole (2,4,6-TBA), and the microbial variation during the microbial O-methylation were investigated in annular reactors (ARs) with three coupon materials. For precursors, 42.5% of 2-CP and 68.9% of 2,4-DCP decayed during the reaction. Among the five HAs, the formation rate constant followed an order of 2,4,6-TCA > 2-CA > 2,4,6-TBA > 2,4-DCA ~ 2,3,6-TCA, while [HA]max followed a totally opposite one. The simulated flow velocity had no significant effect (p > 0.05) on HA formation. Ductile iron (DI) AR could produce more HAs than stainless steel (SS) and polyvinyl chloride (PVC) ARs. The final HA molar concentration followed an order of 2,3,6-TCA > 2,4-DCA > 2,4,6-TBA ~ 2,4,6-TCA > 2-CA, which might be explained by multiple factors including HP's dissociation degree, halogen atom's steric hindrance and specificity of HP O-methyltransferases. During the reaction, the microbial biomass dramatically increased 6.8-9.0 times in bulk water but dropped significantly on coupon biofilms. The effect of HPs significantly changed the bacterial communities on coupon in terms of composition and diversity, and declined the relative abundance of HA-producing bacteria, while fungi and their HA-producing genus showed better resistance ability towards HPs. By using Pearson correlation analysis, a significant correlation (p = 0.0003) was found between [HA]max and initial coupon biofilm biomass. Finally, a linear relationship was established between initial total biomass and HA formation potential.
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Affiliation(s)
- Xinyan Zhou
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Kejia Zhang
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, Zhejiang, China.
| | - Tuqiao Zhang
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Yulong Yang
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Miaomiao Ye
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Renjie Pan
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, Zhejiang, China
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Han C, Zhao H, Dong M, Liu YD, Zhong R. The formation mechanism of chloropicrin from methylamine during chlorination: a DFT study. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2019; 21:761-770. [PMID: 30916670 DOI: 10.1039/c8em00581h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Chloropicrin (TCNM) as one of the most frequently detected nitrogenous disinfection byproducts (N-DBPs) has attracted extensive attention due to its high toxicity. Although much research work on TCNM has been done, its formation mechanism during chlorination has not been known clearly yet. In this study, TCNM formation mechanisms from methylamine (MA) during chlorination, including N-chlorination of MA by hypochlorous acid to generate dichloromethylamine (DCMA) first and then oxidation of DCMA to form nitromethane (NM) and chloronitromethane (CNM), and finally TCNM formation from C-chlorination of NM and CNM, were investigated by using the DFT method. The calculated results show that in N-chlorination of MA, 2-3 water molecules involved in the reaction facilitate Cl+ and proton transfer with the activation free energies (ΔG≠) for the first and second chlorination in the range of 4-7 and 14-17 kcal mol-1, respectively, which are in good agreement with the experimental results. Formation of NM and CNM proceeds through a series of elimination, addition, and oxidation reactions with ΔG≠ of the rate-limiting steps being around 34-37 kcal mol-1, and the subsequent C-chlorination of methyl in NM and CNM by hypochlorous acid is a rapid process with ΔG≠ below 7 kcal mol-1. This infers that the TCNM formation mechanism from DCMA is more likely to undergo first N-oxidation and then C-chlorination. These results can explain the experimental findings that the molar yield of TCNM from MA during chlorination is low (<0.1%) whereas that from NM is rather high (∼45%). This work will be helpful to elucidate formation mechanisms of all the halonitromethanes during chlorination.
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Affiliation(s)
- Chunxiu Han
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, China.
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A photochromic waterborne polyurethane-based dye with chemically fixed azobenzene groups. Polym Bull (Berl) 2018. [DOI: 10.1007/s00289-018-2552-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Alexandrou L, Meehan BJ, Jones OAH. Regulated and emerging disinfection by-products in recycled waters. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 637-638:1607-1616. [PMID: 29925195 DOI: 10.1016/j.scitotenv.2018.04.391] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/13/2018] [Accepted: 04/29/2018] [Indexed: 06/08/2023]
Abstract
Disinfection is an integral component of water treatment performed daily on large volumes of water worldwide. Chemical disinfection may result in the unintended production of disinfectant by-products (DBPs) due to reactions between disinfectants and natural organic matter present in the source water. Due to their potential toxicity, levels of DBPs have been strictly regulated in drinking waters for many years. With water reuse now becoming more common around the world DBPs are increasingly becoming a concern in recycled waters, where a much larger amount and variety of compounds may be formed due to a higher abundance and diversity of organic material in the source waters. Regulation of DBPs in recycled waters is limited; generally, drinking water regulations are applied in place of specific guidelines for recycled waters. Such regulations are set for only 11, commonly observed, compounds of the 600+ that may, potentially, be found. In this review an overview of current research in this area is provided, the types of compounds that have been observed, methods for their analysis and possible regulation are also discussed. Through this review it is evident that there is a knowledge gap for the occurrence of DBPs in recycled waters, especially when comparing this information to that available for drinking waters. The concentrations of DBPs observed in recycled waters are seen to be higher than those in drinking water, though still within potable threshold limits. It is clear that there is a need for the analysis and understanding of a larger suite of compounds in recycled waters, as these will most likely be the source of future, global renewable water.
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Affiliation(s)
- Lydon Alexandrou
- Australian Centre for Research on Separation Science (ACROSS), School of Science, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia
| | - Barry J Meehan
- School of Science, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia
| | - Oliver A H Jones
- Australian Centre for Research on Separation Science (ACROSS), School of Science, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia.
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