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Yu P, Guo Z, Wang T, Wang J, Guo Y, Zhang L. Elucidating the photodegradation mechanism of octylisothiazolinone and dichlorooctylisothiazolinone in surface water: An in-depth comprehensive analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 946:174185. [PMID: 38909814 DOI: 10.1016/j.scitotenv.2024.174185] [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: 04/19/2024] [Revised: 06/07/2024] [Accepted: 06/20/2024] [Indexed: 06/25/2024]
Abstract
Octylisothiazolinone (OIT) and Dichlorooctylisothiazolinone (DCOIT), widely used antibacterial agents in coatings, have seen a sharp increase in use in response to the Coronavirus disease 2019 (Covid-19) pandemic, ultimately leading to their increase in the aquatic environment. However, their photodegradation process in surface water is still unclear. The purpose of this study is to investigate the photodegradation kinetics and mechanisms of OIT and DCOIT in natural water environments. Under simulated solar irradiation, they undergo direct photolysis in both natural freshwater and seawater mainly via their excited singlet states, while no self-sensitization photolysis was observed. The direct photolysis rate constants of OIT and DCOIT were 1.19 ± 0.07 and 0.57 ± 0.03 h-1, respectively. In addition, dissolved organic matter (DOM), NO3- and Cl- in natural waters did not contribute significantly to the photodegradation, and the light screening effect of DOM was identified as the main inhibiting factor. The photodegradation half-life of OIT was estimated to be 0.66 to 1.69 days, while the half-life of DCOIT was as high as 20.9 days during winter in surface water at 30°N latitude. Ring opening of the N-S bond and covalent bond breaking between CN are the main pathways for the photodegradation of OIT and DCOIT, which is verified by density-functional theory calculations. Ecological Structure Activity Relationships (ECOSAR) results indicate that OIT and DCOIT have "Very Toxic" biological toxicity, and the acute toxicity of their products is significantly reduced. It is noteworthy that the toxicity of the products of DCOIT is generally higher than that of OIT, and the chronic toxicity of most of the products is still above the "Toxic" level. Therefore, an in-depth understanding of the photodegradation mechanisms of OIT and DCOIT in aqueous environments is crucial for accurately assessing their ecological risks in natural water environments.
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Affiliation(s)
- Pengfei Yu
- Key Laboratory of Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Zhongyu Guo
- Department of Civil and Environmental Engineering, Tokyo Institute of Technology, Meguro-Ku, Tokyo 152-8552, Japan
| | - Tingting Wang
- Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Jieqiong Wang
- College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China
| | - Yuchen Guo
- College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China
| | - Lilan Zhang
- Key Laboratory of Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
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Yu P, Guo Z, Wang J, Guo Y, Wang T, Zhang L. Insight into the photodegradation of methylisothiazolinone and benzoisothiazolinone in aquatic environments. WATER RESEARCH 2024; 265:122301. [PMID: 39173356 DOI: 10.1016/j.watres.2024.122301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 07/29/2024] [Accepted: 08/18/2024] [Indexed: 08/24/2024]
Abstract
Methylisothiazolinone (MIT) and Benzisothiazolinone (BIT) are two widely used non-oxidizing biocides of isothiazolinones. Their production and usage volume have sharply increased since the pandemic of COVID-19, inevitably leading to more release into water environment. However, their photochemical behaviors in water environment are still unclear. Therefore, this study investigated photodegradation properties of MIT and BIT in natural water under simulated sunlight. The results demonstrated that direct photolysis was mainly responsible for their photodegradation which occurred through their excited singlet states rather than triplet states. The quantum yields of MIT and BIT photodegradation were 11 - 13.6 × 10-4 and 2.43 - 5.79 × 10-4, respectively. pH had almost no effect on the photodegradation of MIT, while the photodegradation of BIT was significantly promoted under alkaline condition due to abundance of BIT in its deprotonated form (BIT-N-). Cl-, NO3- and dissolved organic matter (DOM) in natural water inhibited the photodegradation of both MIT and BIT, with the light screening effect of DOM being the most significantly inhibitory factor. The addition of other isothiazolinones, which possibly coexisted with MIT and BIT in actual condition, slightly inhibited the photodegradation of MIT and BIT. The estimated half-life under natural sunlight at a 30°N latitude was estimated to be approximately 1.1 days. The photodegradation pathways of MIT and BIT are similar, primarily initiated from the ring-opening at the N-S bond, with Frontier electron densities (FED) calculations suggesting the likelihood of oxidation and ·OH addition reactions at the O, N, and S sites. While the photodegradation products exhibited significantly reduced acute toxicity compared to their parent compounds, they nonetheless posed substantial chronic toxicity. These insights are vital for assessing the ecological impacts of MIT and BIT in aquatic environments.
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Affiliation(s)
- Pengfei Yu
- Key Laboratory of Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing, 400045, China; State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China
| | - Zhongyu Guo
- Department of Civil and Environmental Engineering, Tokyo Institute of Technology, Meguro-Ku, Tokyo, 152-8552, Japan
| | - Jieqiong Wang
- College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, China
| | - Yuchen Guo
- College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, China
| | - Tingting Wang
- RIKEN-Center for Computational Science, Kobe, Hyogo, 650-0047, Japan
| | - Lilan Zhang
- Key Laboratory of Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing, 400045, China; State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China
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Pan J, Zhang S, Qiu X, Ding L, Liang X, Guo X. Molecular Weights of Dissolved Organic Matter Significantly Affect Photoaging of Microplastics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:13973-13985. [PMID: 39046080 DOI: 10.1021/acs.est.4c04608] [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: 07/25/2024]
Abstract
The fate of ubiquitous microplastics (MPs) is largely influenced by dissolved organic matter (DOM) in aquatic environments, which has garnered significant attention. The reactivity of DOM is reported to be greatly regulated by molecular weights (MWs), yet little is known about the effects of different MW DOM on MP aging. Here, the aging behavior of polystyrene MPs (PSMPs) in the presence of different MW fulvic acids (FAs) and humic acids (HAs) was systematically investigated. Under ultraviolet (UV) illumination, O/C of PSMPs aged for 96 h surged from 0.008 to 0.146 in the lower MW FA (FA<1kDa) treatment, suggesting significant PSMP aging. However, FA exhibited a stronger effect on facilitating PSMP photoaging than HA, which can be attributed to the fact that FA<1kDa contains more quinone and phenolic moieties, demonstrating a higher redox capacity. Meanwhile, compared to other fractions, FA<1kDa was more actively involved in the increase of different reactive species yields by 50-290%, including •OH, which plays a key role in PSMP photoaging, and contributed to a 25% increase in electron-donating capacity (EDC). This study lays a theoretical foundation for a better understanding of the environmental fate of MPs.
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Affiliation(s)
- Jianrui Pan
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Shilong Zhang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xinran Qiu
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Ling Ding
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xujun Liang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
- Key Laboratory of Plant Nutrition and the Agro-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China
| | - Xuetao Guo
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
- Key Laboratory of Plant Nutrition and the Agro-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China
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Xie WQ, Gong YX. Measurement of permanganate index in environmental water via indirect phase-conversion strategy. J Chromatogr A 2024; 1728:464987. [PMID: 38821034 DOI: 10.1016/j.chroma.2024.464987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 05/06/2024] [Accepted: 05/09/2024] [Indexed: 06/02/2024]
Abstract
In this work, we proposed an indirect phase-conversion strategy to construct a new approach for accurately and efficiently determining the permanganate index in water samples via headspace GC measurement. After the reducible substances in water reacted with excess potassium permanganate, the remaining potassium permanganate underwent a reaction with sodium oxalate under acidic conditions. The carbon dioxide generated from the gas-evolving reaction was then analyzed by headspace GC. Our findings showed that this new approach boasts high precision (relative standard deviation ≤ 2.18%) and accuracy for permanganate index analysis, thus validating the effectiveness of this new method in analyzing permanganate index. The introduction of the indirect phase-conversion strategy in this study is expected to set a precedent for further advancements in methodologies designed to indirectly evaluate substances capable of undergoing gas-producing reactions.
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Affiliation(s)
- Wei-Qi Xie
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
| | - Yi-Xian Gong
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
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Wang H, Wang S, Jia Z, Li H, Wang J, Zhang T, Dong J, Yang P, Chen J, Ji Y, Lu J. Photo-transformation of isoproturon under UV-A irradiation: The synergy of nitrite and natural organic matter. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 353:124153. [PMID: 38750808 DOI: 10.1016/j.envpol.2024.124153] [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: 03/11/2024] [Revised: 04/23/2024] [Accepted: 05/12/2024] [Indexed: 05/21/2024]
Abstract
Isoproturon (IPU), a widely utilized phenylurea herbicide, is recognized as an emerging contaminant. Previous studies have predominantly attributed the degradation of IPU in natural waters to indirect photolysis by natural organic matter (NOM). Here, we demonstrate that nitrite (NO2-) also serves as an important photosensitizer that induces the photo-degradation of IPU. Through radical quenching tests, we identify hydroxyl radicals (•OH) and nitrogen dioxide radicals (NO2•) originating from NO2- photolysis as key players in IPU degradation, resulting in the generation of a series of hydroxylated and nitrated byproducts. Moreover, we demonstrate a synergistic effect on the photo-transformation of IPU when both NOM and NO2- are present in the reaction mixture. The observed rate constant (kobs) for IPU removal increases to 0.0179 ± 0.0002 min-1 in the co-presence of NO2- (50 μM) and NOM (2.5 mgC/L), surpassing the sum of those in the presence of each alone (0.0135 ± 0.0004 min-1). NOM exhibits multifaceted roles in the indirect photolysis of IPU. It can be excited by UV and transformed to excited triplet states (3NOM*) which oxidize IPU to IPU•+ that undergoes further degradation. Simultaneously, NOM can mitigate the reaction by reducing the IPU•+ intermediate back to the parent IPU. However, the presence of NO2- alters this dynamic, as IPU•+ rapidly couples with NO2•, accelerating IPU degradation and augmenting the formation of mono-nitrated IPU. These findings provide in-depth understandings on the photochemical transformation of environmental contaminants, especially phenylurea herbicides, in natural waters where NOM and NO2- coexist.
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Affiliation(s)
- Haiyan Wang
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Sunxinyi Wang
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Zixuan Jia
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Hao Li
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiayu Wang
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Teng Zhang
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiayue Dong
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Peizeng Yang
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
| | - Jing Chen
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yuefei Ji
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Junhe Lu
- Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
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Wang Z, Lin X, Yang K, Lin D. Differential photodegradation processes of adsorbed polychlorinated biphenyls on biochar colloids with various pyrolysis temperatures. WATER RESEARCH 2024; 251:121174. [PMID: 38277821 DOI: 10.1016/j.watres.2024.121174] [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: 08/15/2023] [Revised: 12/31/2023] [Accepted: 01/19/2024] [Indexed: 01/28/2024]
Abstract
Despite the crucial role of photodegradation in the environmental transformation of organic pollutants, the photodegradation process of organic pollutants irreversibly absorbed on biochar colloids (BCCs) remains poorly understood. This study investigated the photodegradation processes and mechanisms of 2,4,4'-trichlorobiphenyl (PCB28) adsorbed on BCCs released from bulk biochars derived from bamboo chips at pyrolysis temperatures of 300, 500, and 700 °C. Results show that BCCs-adsorbed PCB28 could be degraded under simulated solar illumination (95-105 mW·cm-2) but at decreased photodegradation rates compared to the dissolved PCB28. The inhibition effect of BCCs on the PCB28 photodegradation increased with increasing pyrolysis temperature. After adsorptive binding to BCCs, the half-life of PCB28 (0.1 mg/L) was prolonged from 2.65 h for the dissolved PCB28 alone in deionized water to 7.48, 40.67, and 81.82 h in the presence of BCC300, BCC500, and BCC700 (5.0 mg/L), respectively. Mechanistically, the photodegradation of adsorbed pollutants was regulated by the photogenerated free radicals and surface functional groups of the low-temperature BCCs, as well as the defects and direct electron transfer capabilities of the high-temperature BCCs; PCB28 adsorbed on the low-temperature BCCs accepted electrons from persistent free radicals under light illumination, which led to PCB28 dechlorination, followed by ring-opening oxidation through hydroxyl radical attack, ultimately resulting in progressive mineralization; singlet oxygen caused preferential ring opening of adsorbed PCB28 on the high-temperature BCCs, preceding dechlorination. The photodegradation of BCCs-adsorbed PCB28 remained significant though more or less being inhibited under the effects of water pH, ionic strength, dissolved organic matters (humic acid and fulvic acid), and in natural water samples. These findings contribute to a better understanding of the structural properties of BCCs that impact phototransformation processes of adsorbed pollutants and facilitate an accurate assessment of the environmental risk associated with biochar application.
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Affiliation(s)
- Zhongmiao Wang
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
| | - Xintong Lin
- School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Kun Yang
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
| | - Daohui Lin
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; Zhejiang Ecological Civilization Academy, Anji 313300, China.
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