ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2020
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IF 7.864
Qian-Yuan Wu,Lu-Lin Yang,Xin-Yang Zhang,Wen-Long Wang,Yao Lu,Ye Du,Yun Lu,Hong-Ying Hu
Ammonia (NH4+) and hydrogen peroxide (H2O2) have been widely used to inhibit bromate formation during ozonation. However, organic byproducts can also pose a risk under these conditions. During bromate inhibition, the influence of NH4+ and H2O2 on organic byproducts and their toxicity should be elucidated. Our study found that NH4+ suppressed organic bromine, but might result in increased toxicity. Adding 0.5 mg/L of NH4+–N substantially increased both the formation of cytotoxicity and genotoxicity (DNA double-strand breaks) of organic byproducts from 0.6 to 1.6 mg-phenol/L, and from 0.3 to 0.8 μg-4-NQO/L (0.5 mg/L Br–, 5 mg/L O3). NH4+ decreased bromate, but increased the overall toxicity of the integrated byproducts (organic byproducts and bromate). Organic nitrogen measurements and 15N isotope analysis showed enhanced incorporation of nitrogen into organic matter when NH4+ and Br– coexisted during ozonation. NH4+ decreased the formation of brominated acetonitriles, but enhanced the formation of brominated nitromethanes and brominated acetamides. These brominated nitrogenous byproducts were partially responsible for this increase in toxicity. Different from ammonia, H2O2 could reduce both bromate and the toxicity of organic byproducts. In the presence of 0.5 mg/L Br– and 10 mg/L O3, adding H2O2 (0.5 mM) substantially suppressed bromate, cytotoxicity formation and genotoxicity formation by 88%, 63% and 67%. This study highlights that focusing on bromate control with NH4+ addition might result in higher toxicity. Efforts are needed to effectively control the toxicities of bromate and organic byproducts simultaneously.
研究领域:
环境科学
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毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2017
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IF 6.216
Jing Xu,Xiangyi Shen,Duanli Wang,Chuxuan Zhao,Zizheng Liu,Ivan P. Pozdnyakov,Feng Wu,Jun Xia
The usage of p -arsanilic acid (ASA) in livestock and poultry farms leads to its release into the environment. The phototransformation of ASA generates toxic inorganic arsenic species and organic by-products, which affects the water security of the peripheral river basin. In this work, we have investigated the pH-dependent kinetics and mechanisms of ASA photolysis under Ultraviolet-C (UV-C) light (254 nm) irradiation in the pH range 1–11 in the absence of oxygen. The degradation rate of ASA, the ratio of the generated inorganic arsenic species, and the amount of primary organic by-products were determined under the aforesaid conditions. Our results clearly showed the pH-dependent photochemistry of ASA. The photolysis rate was low under acidic conditions, and As(III) and p -aminophenol were the main products. With increasing pH, the photolysis rate increased significantly, and As(V) and aniline became the main products. A pH-based kinetic model has been established that allows prediction of the generation rates of As(III), As(V), p -aminophenol, and aniline according to the photolysis rate of ASA.
研究领域:
环境科学
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化学动力学
✓ 已验证
产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2021
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IF 7.963
Xiaoyu Liu,Yuntao Hong,Shunke Ding,Wei Jin,Shengkun Dong,Rong Xiao,Wenhai Chu
Due to the spread of coronavirus disease 2019 (COVID-19), large amounts of antivirals were consumed and released into wastewater, posing risks to the ecosystem and human health. Ozonation is commonly utilized as pre-oxidation process to enhance the disinfection of hospital wastewater during COVID-19 spread. In this study, the transformation of ribavirin, antiviral for COVID-19, during ozone/PMS‑chlorine intensified disinfection process was investigated. •OH followed by O 3 accounted for the dominant ribavirin degradation in most conditions due to higher reaction rate constant between ribavirin and •OH vs. SO 4 • − (1.9 × 10 9 vs. 7.9 × 10 7 M −1 s −1 , respectively). During the O 3 /PMS process, ribavirin was dehydrogenated at the hydroxyl groups first, then lost the amide or the methanol group. Chloride at low concentrations (e.g., 0.5– 2 mg/L) slightly accelerated ribavirin degradation, while bromide, iodide, bicarbonate, and dissolved organic matter all reduced the degradation efficiency. In the presence of bromide, O 3 /PMS process resulted in the formation of organic brominated oxidation by-products (OBPs), the concentration of which increased with increasing bromide dosage. However, the formation of halogenated OBPs was negligible when chloride or iodide existed. Compared to the O 3 /H 2 O 2 process, the concentration of brominated OBPs was significantly higher after ozonation or the O 3 /PMS process. This study suggests that the potential risks of the organic brominated OBPs should be taken into consideration when ozonation and ozone-based processes are used to enhance disinfection in the presence of bromide amid COVID-19 pandemic.
研究领域:
环境科学
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公共卫生
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药学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2020
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IF 9.038
Na Li,Jie Cheng,Xin Xing,Yonggang Sun,Zhengping Hao
Clarifying the oxidative products and their formation mechanisms in the catalytic oxidation of chlorinated volatile organic compounds is important to provide detailed understanding of the degradation of pollutants with the simultaneous removal of secondary pollutants. In this study, catalytic oxidation of 1,2-dichlorobenzene (1,2-DCB) using commonly commercial catalysts (Pd/γ-Al 2 O 3 , Pd/ZSM-5, and Pd/SiO 2 ) was investigated. During the oxidation processes, substantial amounts of polychlorinated organic by-products, such as trichlorobenzene, tetrachlorobenzene and pentachlorobenzene, were detected. The reaction temperature and types of supports played a vital role in the formation of chlorinated organic by-products. With an increase of the reaction temperature, the degree of chlorination of the organic by-products increased gradually, and the concentration of polychlorinated organic by-products was increased sharply at low temperatures and then decreased when the reaction temperature was above 450 °C. Meanwhile, the amounts of polychlorinated organic by-products increased with an increasing silicate-to-aluminium ratio. Furthermore, based on the distribution of chlorinated organic by-products and characterization results of pyridine from FTIR, XPS, UV–vis-DRs, and in situ FTIR, the formation mechanisms of the polychlorinated organic compounds were proposed.
研究领域:
环境科学
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化学工程
✓ 已验证
DOI
高影响因子
LANGMUIR
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2021
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IF 3.882
Binyao Liu,Xiaoqin Nie,Yi Tang,Shan Yang,Liang Bian,Faqin Dong,Huichao He,Yong Zhou,Kun Liu
The thermal-condensation method is widely used for the synthesis of K-doped g-C3N4 photocatalysts, but the presence of organic byproducts in the resultant products is often overlooked in previous reports. Here, we demonstrated the universal presence of organic byproducts in K-doped g-C3N4 synthesized by typical thermal condensation of KOH/melamine, KOH/dicyandiamide, or KOH/urea. Taking the K-doped g-C3N4 photocatalysis for the degradation of dimethyl phthalate as an example, the negative influence of the organic byproducts on K-doped g-C3N4 photocatalysis was confirmed. Specifically, the organic byproducts can be gradually dissolved into the photocatalytic system of K-doped g-C3N4 as new and stable pollutants. Based on the solubility investigations on the byproducts in several solvents, hot-water washing was demonstrated to be a relatively effective approach to remove the organic byproducts from K-doped g-C3N4. The formation of organic byproducts during the synthesis of K-doped g-C3N4 could be ascribed to the fact that the presence of K salts in melamine, dicyandiamide, or urea molecules results in their insufficient thermal condensation into expected g-C3N4. The present work provides objective information about the K-doped g-C3N4 photocatalysts and reminds researchers about the influence of the organic byproducts on the applications of the other impurity-doped g-C3N4 photocatalysts.
研究领域:
材料化学
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环境催化
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光催化
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纳米材料
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污染物降解
✓ 已验证
DOI
高影响因子
ENVIRONMENTAL POLLUTION
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2020
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IF 6.793
Yi Liu,Majda Mekic,Luca Carena,Davide Vione,Sasho Gligorovski,Gan Zhang,Biao Jin
Triclosan (TCS) is an antimicrobial compound ubiquitously found in surface waters throughout the world. Although several studies have focused on the photochemical degradation of TCS, there is still limited knowledge about its environmental fate . In this study, we got molecular-level insights into the photochemical degradation of TCS. Significant stable carbon isotope fractionation was observed during photodegradation ; different bond-cleavage reaction pathways under different photolytic conditions were characterized, using compound specific isotope analysis (CSIA). Photochemical modeling of TCS photodegradation showed that direct photolysis would be the main transformation pathway if pH > 7, even in presence of dissolved organic matter . Moreover, by use of ultrahigh resolution mass spectrometry, FT-ICR-MS, a broad and complex spectrum of organic by-products (some of which potentially toxic, as assessed by a quantitative structure-activity relationship approach) were identified. A detailed reaction mechanism was developed on the basis of the detected compounds. A possible sequence of steps leading to some of the detected product compounds in aqueous solution is suggested.
研究领域:
环境科学
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分析化学
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质谱学
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同位素分析
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光化学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）