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Zhou H, Duan X, Huang B, Zhong S, Cheng C, Sharma VK, Wang S, Lai B. Isotope Techniques in Chemical Wastewater Treatment: Opportunities and Uncertainties. Angew Chem Int Ed Engl 2025; 64:e202422892. [PMID: 40040468 PMCID: PMC12051784 DOI: 10.1002/anie.202422892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2024] [Revised: 03/03/2025] [Accepted: 03/04/2025] [Indexed: 03/06/2025]
Abstract
A comprehensive and in-depth analysis of reaction mechanisms is essential for advancing chemical water treatment technologies. However, due to the limitations of conventional experimental and analytical methods, the types of reactive species and their generation pathways are commonly debatable in many aqueous systems. As highly sensitive diagnostic tools, isotope techniques offer deeper insights with minimal interference from reaction conditions. Nevertheless, precise interpretations of isotope results remain a significant challenge. Herein, we first scrutinized the fundamentals of isotope chemistry and highlighted key changes induced by the isotope substitution. Next, we discussed the application of isotope techniques in kinetic isotope effects, presenting a roadmap for interpreting KIE in sophisticated systems. Furthermore, we summarized the applications of isotope techniques in elemental tracing to pinpoint reaction sites and identify dominant reactive species. Lastly, we propose future research directions, highlighting critical considerations for the rational design and interpretation of isotope experiments in environmental chemistry and related fields.
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Affiliation(s)
- Hongyu Zhou
- State Key Laboratory of Hydraulics and Mountain River EngineeringCollege of Architecture and Environment, Sichuan UniversityChengdu610065China
- School of Chemical EngineeringThe University of AdelaideAdelaideSA5005Australia
| | - Xiaoguang Duan
- School of Chemical EngineeringThe University of AdelaideAdelaideSA5005Australia
| | - Bingkun Huang
- State Key Laboratory of Hydraulics and Mountain River EngineeringCollege of Architecture and Environment, Sichuan UniversityChengdu610065China
| | - Shuang Zhong
- School of Chemical EngineeringThe University of AdelaideAdelaideSA5005Australia
| | - Cheng Cheng
- School of Chemical EngineeringThe University of AdelaideAdelaideSA5005Australia
| | - Virender K. Sharma
- Department of Chemical, Environmental and MaterialsUniversity of Miami1251 Memorial DriveCoral GablesFlorida33146USA
| | - Shaobin Wang
- School of Chemical EngineeringThe University of AdelaideAdelaideSA5005Australia
| | - Bo Lai
- State Key Laboratory of Hydraulics and Mountain River EngineeringCollege of Architecture and Environment, Sichuan UniversityChengdu610065China
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2
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Murata Y, Sakai H. Abating a micropollutant epinastine by UV-based advanced oxidation processes: Comparison for UV/hydrogen peroxide, UV/persulfate, and UV/chlorine, impacts of bromide contents, and formation of DBPs during post-chlorination. CHEMOSPHERE 2025; 374:144206. [PMID: 39946939 DOI: 10.1016/j.chemosphere.2025.144206] [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: 12/05/2024] [Revised: 01/13/2025] [Accepted: 02/07/2025] [Indexed: 03/03/2025]
Abstract
Anthropogenic organic compounds, such as pharmaceuticals and personal care products, contaminate water, posing toxicological risks caused by either their parent compounds or transformation products. This study compares ultraviolet (UV)-based advanced oxidation processes (UV/hydrogen peroxide, UV/persulfate, and UV/chlorine) for the abatement of an antihistamine drug epinastine. UV light at 254 nm was irradiated upon solutions containing 10 μM epinastine and 100 μM oxidant. UV/chlorine degraded epinastine most effectively at pH 6.0-8.0; considerable contributions by reactive chlorine species and hydroxyl radicals were quantified using probe compounds. Furthermore, the degradation efficiency of the UV/chlorine treatment persisted with a halved chlorine dosage. Additionally, the types and concentrations of disinfection byproducts (DBPs) produced during UV/chlorine treatment with or without post-chlorination varied depending on the concentrations of chlorine or bromide. By comparing estimated DBP formations at a constant degradation rate of epinastine, UV/chlorine formed smaller concentrations of DBPs. Consequently, this study experimentally revealed that UV/chlorine is superior to UV/hydrogen peroxide and UV/persulfate for degrading epinastine at the possible pH and bromide content in the environment and controlling toxicological risks caused by disinfection DBPs formation by optimising chlorine dosage and UV fluence.
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Affiliation(s)
- Yuichiro Murata
- Department of Civil and Environmental Engineering, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji-city, Tokyo, 1920397, Japan.
| | - Hiroshi Sakai
- Department of Civil and Environmental Engineering, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji-city, Tokyo, 1920397, Japan.
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3
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Gao Z, Liu YL, Wang XS, Zhao XN, Zhu ZY, Ma CN, Cui CW, Ma J, Wang L. Phenols coupled during oxidation upstream of water treatment would generate higher toxic coupling phenolic disinfection by-products during chlorination disinfection. JOURNAL OF HAZARDOUS MATERIALS 2025; 483:136678. [PMID: 39616842 DOI: 10.1016/j.jhazmat.2024.136678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Revised: 11/16/2024] [Accepted: 11/25/2024] [Indexed: 01/28/2025]
Abstract
Phenolic compounds usually produce coupling phenols during the upstream oxidation treatment of water, but the disinfection by-products (DBPs) of coupling phenols in the subsequent disinfection process have been overlooked. Herein, we demonstrated the generation and higher toxicity of these DBPs. In Songhua River water, 0.355 ng/L 4-(4-bromophenoxy)phenol and 122.67 ng/L phenol were detected. Pre-oxidation with K2FeO4 and KMnO4 resulted in the formation of 0.68 ng/L and 0.506 ng/L 4-(4-iodophenoxy)phenol in subsequent disinfection, respectively, which were 2-3 times that without pre-oxidation. Coupling of phenolic compounds during pre-oxidation and then halogenated during chlorination was shown to be the main pathway for the generation of coupling phenolic DBPs. The maximum rate constants for the reactions of hypochlorous acid with phenol and its coupling products (4-phenoxyphenol, 2,2'-biphenol, and [1,1'-biphenyl]-2,4'-diol) were 115.61 M-1s-1, 65.85 M-1s-1, 143.13 M-1s-1, and 212.52 M-1s-1, respectively, with 2,2'-biphenol and [1,1'-biphenyl]-2,4'-diol breaking through lower energy barriers and releasing more energy than phenol. This indicated coupling phenols have a higher potential to form DBPs. Additionally, coupling phenolic DBPs (4-(4-chlorophenoxy)phenol, 4-(4-bromophenoxy)phenol, and 4-(4-iodophenoxy)phenol) was 1-3 orders of magnitude more toxic than their precursors (4-phenoxyphenol, 2,2'-biphenol, [1,1'-biphenyl]-2,4'-diol, and phenol) and uncoupled DBPs (4-iodophenol). Therefore, the formation and hazards of coupling phenolic DBPs require more attention.
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Affiliation(s)
- Zhi Gao
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Yu-Lei Liu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Xian-Shi Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Xiao-Na Zhao
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Zhi-Yu Zhu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Cai-Ni Ma
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Chong-Wei Cui
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Jun Ma
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Lu Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
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4
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Liu C, Liu H, Hu C, Chow AT, Karanfil T. Molecular Alterations of Algal Organic Matter in Oxidation Processes: Implications to the Formation of Disinfection Products. ACS ES&T WATER 2024; 4:5890-5901. [PMID: 39698554 PMCID: PMC11650642 DOI: 10.1021/acsestwater.4c00855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2024] [Revised: 11/14/2024] [Accepted: 11/15/2024] [Indexed: 12/20/2024]
Abstract
Seasonal algal blooms in surface waters can adversely impact drinking water quality. Oxidative treatment has been demonstrated as an effective measure for the removal of algal cells. However, this, in turn, leads to the release of algal organic matter (AOM). Effects of oxidative treatment using chlorine, bromine, chloramine, ozone, and permanganate on the molecular alterations of the AOM were studied using Fourier transform ion cyclotron resonance mass spectrometry. Increased chemodiversity, decreased aromaticity, and elevated average oxidation state of carbon () were observed after oxidation. Of the oxidants, ozone caused the most pronounced changes. There was a positive correlation between the increases in and reduction potentials of oxidants (i.e., ozone > chlorine ≈ bromine > permanganate > chloramine). Oxygen transfer and oxidative dehydrogenation were major pathways (42.3-52.8%) for AOM oxidation, while other pathways (e.g., deamination, dealkylation, decarboxylation, and halogen substitution/addition) existed. Moreover, the halogen substitution/addition pathway only accounted for 1.3-10.3%, even for chlorine or bromine treatment. Oxidative treatment could decrease the reactivity of AOM in postchlorination, thereby decreasing the trichloromethane formation. However, the formation of oxygen-rich disinfection byproducts (DBPs, e.g., trichloronitromethane) could be favored, especially for ozonation. This study provides molecular-level insights into the effects of oxidative treatment on AOM and derived DBP formation in water treatment.
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Affiliation(s)
- Chao Liu
- Key
Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of
Sciences, Beijing 100085, China
- Department
of Environmental Engineering and Earth Sciences, Clemson University, Anderson, South Carolina 29625, United States
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Hang Liu
- Key
Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of
Sciences, Beijing 100085, China
| | - Chengzhi Hu
- Key
Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of
Sciences, Beijing 100085, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Alex T. Chow
- Department
of Earth and Environmental Sciences, Faculty
of Science, The Chinese University of Hong Kong, Hong Kong SAR 999077, China
| | - Tanju Karanfil
- Department
of Environmental Engineering and Earth Sciences, Clemson University, Anderson, South Carolina 29625, United States
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Qin W, Zheng S, Guo K, Yang M, Fang J. Predicting reaction kinetics of reactive bromine species with organic compounds by machine learning: Feature combination and knowledge transfer with reactive chlorine species. JOURNAL OF HAZARDOUS MATERIALS 2024; 480:136410. [PMID: 39509874 DOI: 10.1016/j.jhazmat.2024.136410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2024] [Revised: 10/19/2024] [Accepted: 11/04/2024] [Indexed: 11/15/2024]
Abstract
Reactive bromine species (RBS) such as bromine atom (Br•) and dibromine radical (Br2•-) are important oxidative species accounting for the transformation of organic compounds in bromide-containing water. This study developed quantitative structure-activity relationship (QSAR) models to predict second order rate constants (k) of RBS by machine learning (ML) and conducted knowledge transfer between RBS and reactive chlorine species (RCS, e.g., Cl• and Cl2•-) to improve model performance. The ML-based models (RMSEtest = 0.476 -0.712) outperformed the multiple linear regression-based models (RMSEtest = 0.572 -3.68) for predicting k of RBS. In addition, the combination of molecular fingerprints (MFs) and quantum descriptors (QDs) as input features improved the performance of ML-based models (RMSEtest = 0.476 -0.712) compared to those developed by MFs (RMSEtest = 0.524 -0.834) or QDs (RMSEtest = 0.572 -0.806) alone. EHOMO and Egap were identified to be the most important features affecting k of RBS based on SHAP analysis. A unified model integrating the datasets of four reactive halogen species (RHS, e.g., Br•, Br2•-, Cl• and Cl2•-) was further developed (R2test = 0.802), which showed better predictive performance than the individual models (R2test = 0.521 -0.776). Meanwhile, the model performance changed differently by employing knowledge transfer among RHS, which was improved for Br•/Cl•, mixed for Br•/Br2•- and Cl•/Cl2•-, but worse for Br2•-/Cl2•-. This study provides useful tools for predicting k of RHS in aqueous environments.
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Affiliation(s)
- Wenlei Qin
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Shanshan Zheng
- School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen 518060, China
| | - Kaiheng Guo
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Ming Yang
- HFI Huafu International, Guangzhou 510641, China
| | - Jingyun Fang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
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Yang S, Sun S, Xie Z, Dong Y, Zhou P, Zhang J, Xiong Z, He CS, Mu Y, Lai B. Comprehensive Insight into the Common Organic Radicals in Advanced Oxidation Processes for Water Decontamination. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:19571-19583. [PMID: 39442087 DOI: 10.1021/acs.est.4c06676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2024]
Abstract
Radical-based advanced oxidation processes (AOPs) are among the most effective technologies employed to destroy organic pollutants. Compared to common inorganic radicals, such as •OH, O2•-, and SO4•-, organic radicals are widespread, and more selective, but are easily overlooked. Furthermore, a systematic understanding of the generation and contributions of organic radicals remains lacking. In this review, we systematically summarize the properties, possible generation pathways, detection methods, and contributions of organic radicals in AOPs. Notably, exploring organic radicals in AOPs is challenging due to (1) limited detection methods for generated organic radicals; (2) controversial organic radical-mediated reaction mechanisms; and (3) rapid transformation of organic radicals as reaction intermediates. In addition to their characteristics and reactivity, we examine potential scenarios of organic radical generation in AOPs, including during the peroxide activation process, in water matrices or with coexisting organic pollutants, and due to the addition of quenching agents. Subsequently, we summarize various methods for organic radical detection as reported previously, such as electron paramagnetic resonance spectroscopy (EPR), 31P nuclear magnetic resonance spectroscopy (31P NMR), liquid/gas chromatography-mass spectroscopy (GC/LC-MS), and fluorescence probes. Finally, we review the contributions of organic radicals to decontamination processes and provide recommendations for future research.
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Affiliation(s)
- Shurun Yang
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
- Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
| | - Si Sun
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
- Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
| | - Zhihui Xie
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
- Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
| | - Yudan Dong
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
- Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
| | - Peng Zhou
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
- Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
| | - Jing Zhang
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
- Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
| | - Zhaokun Xiong
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
- Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
| | - Chuan-Shu He
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
- Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
| | - Yang Mu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Bo Lai
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
- Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
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Chi L, Shen H, Jiang K, Cao X, Song X, Yu Z. BTXs removals by modified clay during mitigation of Karenia brevis bloom: Insights from adsorption and transformation. CHEMOSPHERE 2024; 362:142668. [PMID: 38906188 DOI: 10.1016/j.chemosphere.2024.142668] [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: 03/05/2024] [Revised: 06/16/2024] [Accepted: 06/18/2024] [Indexed: 06/23/2024]
Abstract
Harmful algal blooms (HABs), especially those caused by toxic dinoflagellates, are spreading in marine ecosystems worldwide. Notably, the prevalence of Karenia brevis blooms and potent brevetoxins (BTXs) pose a serious risk to public health and marine ecosystems. Therefore, developing an environmentally friendly method to effectively control HABs and associated BTXs has been the focus of increasing attention. As a promising method, modified clay (MC) application could effectively control HABs. However, the environmental fate of BTXs during MC treatment has not been fully investigated. For the first time, this study revealed the effect and mechanism of BTX removal by MC from the perspective of adsorption and transformation. The results indicated that polyaluminium chloride-modified clay (PAC-MC, a typical kind of MC) performed well in the adsorption of BTX2 due to the elevated surface potential and more binding sites. The adsorption process was a spontaneous endothermic process that conformed to pseudo-second-order adsorption kinetics (k2 = 6.8 × 10-4, PAC-MC = 0.20 g L-1) and the Freundlich isotherm (Kf = 55.30, 20 °C). In addition, detailed product analysis using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) indicated that PAC-MC treatment effectively removed the BTX2 and BTX3, especially those in the particulate forms. Surprisingly, PAC-MC could promote the transformation of BTX2 to derivatives, including OR-BTX2, OR-BTX3, and OR-BTX-B5, which were proven to have lower cytotoxicity.
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Affiliation(s)
- Lianbao Chi
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, Qingdao, 266200, China
| | - Huihui Shen
- Qingdao Technical College, Qingdao, 266555, China
| | - Kaiqin Jiang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, Qingdao, 266200, China
| | - Xihua Cao
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, Qingdao, 266200, China
| | - Xiuxian Song
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, Qingdao, 266200, China.
| | - Zhiming Yu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, Qingdao, 266200, China.
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Minakata D. Development of an Elementary Reaction-Based Kinetic Model to Predict the Aqueous-Phase Fate of Organic Compounds Induced by Reactive Free Radicals. Acc Chem Res 2024; 57:1658-1669. [PMID: 38804206 DOI: 10.1021/acs.accounts.4c00021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
ConspectusAqueous-phase free radicals such as reactive oxygen, halogen, and nitrogen species play important roles in the fate of organic compounds in the aqueous-phase advanced water treatment processes and natural aquatic environments under sunlight irradiation. Predicting the fate of organic compounds in aqueous-phase advanced water treatment processes and natural aquatic environments necessitates understanding the kinetics and reaction mechanisms of initial reactions of free radicals with structurally diverse organic compounds and other reactions. Researchers developed conventional predictive models based on experimentally measured transformation products and determined reaction rate constants by fitting with the time-dependent concentration profiles of species due to difficulties in their measurements of unstable intermediates. However, the empirical treatment of lumped reaction mechanisms had a model prediction limitation with respect to the specific parent compound's fate. We use ab initio and density functional theory quantum chemical computations, numerical solutions of ordinary differential equations, and validation of the outcomes of the model with experiments. Sensitivity analysis of reaction rate constants and concentration profiles enables us to identify an important elementary reaction in formating the transformation product. Such predictive elementary reaction-based kinetics models can be used to screen organic compounds in water and predict their potentially toxic transformation products for a specific experimental investigation.Over the past decade, we determined linear free energy relationships (LFERs) that bridge the kinetic and thermochemical properties of reactive oxygen species such as hydroxyl radicals (HO•), peroxyl radicals (ROO•), and singlet oxygen (1O2); reactive halogen species such as chlorine radicals (Cl•) and bromine radicals (Br•); reactive nitrogen species (NO2•); and carbonate radicals (CO3•-). We used literature-reported experimental rate constants as kinetic information. We considered the theoretically calculated aqueous-phase free energy of activation or reaction to be a kinetic or a thermochemical property, and obtained via validated ab initio or density functional theory-based quantum chemical computations using explicit and implicit solvation models. We determined rate-determining reaction mechanisms involved in reactions by observing robust LFERs. The general accuracy of LFERs to predict aqueous-phase rate constants was within a difference of a factor of 2-5 from experimental values.We developed elementary reaction-based kinetic models and predicted the fate of acetone induced by HO• in an advanced water treatment process and methionine by photochemically produced reactive intermediates in sunlit fresh waters. We provided mechanistic insight into peroxyl radical reaction mechanisms and critical roles in the degradation of acetone and the formation of transformation products. We highlighted different roles of triplet excited states of two surrogate CDOMs, 1O2, and HO•, in methionine degradation. Predicted transformation products were compared to those obtained via benchtop experiments to validate our elementary reaction-based kinetic models. Predicting the reactivities of reactive halogen and nitrogen species implicates our understanding of the formation of potentially toxic halogen- and nitrogen-containing transformation products during water treatment processes and in natural aquatic environments.
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Affiliation(s)
- Daisuke Minakata
- Department of Civil, Environmental, and Geospatial Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, United States
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Schmiemann D, Bicks F, Bartels I, Cordes A, Jäger M, Gutmann JS, Hoffmann-Jacobsen K. Enzymatic degradability of diclofenac ozonation products: A mechanistic analysis. CHEMOSPHERE 2024; 358:142112. [PMID: 38677613 DOI: 10.1016/j.chemosphere.2024.142112] [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: 11/23/2023] [Revised: 02/21/2024] [Accepted: 04/21/2024] [Indexed: 04/29/2024]
Abstract
The treatment of waterborne micropollutants, such as diclofenac, presents a significant challenge to wastewater treatment plants due to their incomplete removal by conventional methods. Ozonation is an effective technique for the degradation of micropollutants. However, incomplete oxidation can lead to the formation of ecotoxic by-products that require a subsequent post-treatment step. In this study, we analyze the susceptibility of micropollutant ozonation products to enzymatic digestion with laccase from Trametes versicolor to evaluate the potential of enzymatic treatment as a post-ozonation step. The omnipresent micropollutant diclofenac is used as an example, and the enzymatic degradation kinetics of all 14 detected ozonation products are analyzed by high-performance liquid chromatography coupled with high-resolution mass spectrometry (HPLC-HRMS) and tandem mass spectrometry (MS2). The analysis shows that most of the ozonation products are responsive to chemo-enzymatic treatment but show considerable variation in enzymatic degradation kinetics and efficiencies. Mechanistic investigation of representative transformation products reveals that the hydroxylated aromatic nature of the ozonation products matches the substrate spectrum, facilitating their rapid recognition as substrates by laccase. However, after initiation by laccase, the subsequent chemical pathway of the enzymatically formed radicals determines the global degradability observed in the enzymatic process. Substrates capable of forming stable molecular oxidation products inhibit complete detoxification by oligomerization. This emphasizes that it is not the enzymatic uptake of the substrates but the channelling of the reaction of the substrate radicals towards the oligomerization of the substrate radicals that is the key step in the further development of an enzymatic treatment step for wastewater applications.
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Affiliation(s)
- Dorothee Schmiemann
- Department of Chemistry and Institute for Coatings and Surface Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798, Krefeld, Germany; Institute of Physical Chemistry and CENIDE (Center for Nanointegration), University Duisburg-Essen, Universitätsstraße 5, 45141, Essen, Germany
| | - Florian Bicks
- Department of Chemistry and Institute for Coatings and Surface Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798, Krefeld, Germany
| | - Indra Bartels
- Department of Chemistry and Institute for Coatings and Surface Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798, Krefeld, Germany; Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstraße 5, 45141, Essen, Germany
| | - Arno Cordes
- ASA Spezialenzyme GmbH, Am Exer 19c, 38302, Wolfenbüttel, Germany
| | - Martin Jäger
- Department of Chemistry and Institute for Coatings and Surface Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798, Krefeld, Germany
| | - Jochen Stefan Gutmann
- Institute of Physical Chemistry and CENIDE (Center for Nanointegration), University Duisburg-Essen, Universitätsstraße 5, 45141, Essen, Germany; Deutsches Textilforschungszentrum Nord-West gGmbH, Adlerstr. 1, 47798, Krefeld, Germany
| | - Kerstin Hoffmann-Jacobsen
- Department of Chemistry and Institute for Coatings and Surface Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798, Krefeld, Germany.
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10
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von Gunten U. Oxidation processes and me. WATER RESEARCH 2024; 253:121148. [PMID: 38387263 DOI: 10.1016/j.watres.2024.121148] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/12/2024] [Accepted: 01/14/2024] [Indexed: 02/24/2024]
Abstract
This publication summarizes my journey in the field of chemical oxidation processes for water treatment over the last 30+ years. Initially, the efficiency of the application of chemical oxidants for micropollutant abatement was assessed by the abatement of the target compounds only. This is controlled by reaction kinetics and therefore, second-order rate constant for these reactions are the pre-requisite to assess the efficiency and feasibility of such processes. Due to the tremendous efforts in this area, we currently have a good experimental data base for second-order rate constants for many chemical oxidants, including radicals. Based on this, predictions can be made for compounds without experimental data with Quantitative Structure Activity Relationships with Hammet/Taft constants or energies of highest occupied molecular orbitals from quantum chemical computations. Chemical oxidation in water treatment has to be economically feasible and therefore, the extent of transformation of micropollutants is often limited and mineralization of target compounds cannot be achieved under realistic conditions. The formation of transformation products from the reactions of the target compounds with chemical oxidants is inherent to oxidation processes and the following questions have evolved over the years: Are the formed transformation products biologically less active than the target compounds? Is there a new toxicity associated with transformation products? Are transformation products more biodegradable than the corresponding target compounds? In addition to the positive effects on water quality related to abatement of micropollutants, chemical oxidants react mainly with water matrix components such as the dissolved organic matter (DOM), bromide and iodide. As a matter of fact, the fraction of oxidants consumed by the DOM is typically > 99%, which makes such processes inherently inefficient. The consequences are loss of oxidation capacity and the formation of organic and inorganic disinfection byproducts also involving bromide and iodide, which can be oxidized to reactive bromine and iodine with their ensuing reactions with DOM. Overall, it has turned out in the last three decades, that chemical oxidation processes are complex to understand and to manage. However, the tremendous research efforts have led to a good understanding of the underlying processes and allow a widespread and optimized application of such processes in water treatment practice such as drinking water, municipal and industrial wastewater and water reuse systems.
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Affiliation(s)
- Urs von Gunten
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Duebendorf, Switzerland; ENAC, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale, CH-1000, Lausanne, Switzerland.
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