ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2021
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IF 9.028
Chengxue Ma,Haijun Cheng,Ruixing Huang,Yijie Zou,Qiang He,Xiaoliu Huangfu,Jun Ma
The oxidation of thallium [Tl(I)] to Tl(III) by chlorine (HOCl) is an important process changing its removal performance in water treatment. However, the role of bromide (Br–), a common constituent in natural water, in the oxidation behavior of Tl(I) during chlorination remains unknown. Our results demonstrated that Br– was cycled and acted as a catalyst to enhance the kinetics of Tl(I) oxidation by HOCl over the pH range of 5.0–9.5. Different Tl(I) species (i.e., Tl+ and TlOH(aq)) and reactive bromine species (i.e., HOBr/BrO–, BrCl, Br2O, and BrOCl) were kinetically relevant to the enhanced oxidation of Tl(I). The oxidation by free bromine species became the dominant pathway even at a low Br– level of 50 μg/L for a chlorine dose of 2 mg of Cl2/L. It was found that the reactions of Tl+/BrCl, Tl+/BrOCl, and TlOH(aq)/HOBr dominated the kinetics of Tl(I) oxidation at pH < 6.0, pH 6.0–8.0, and pH > 8.0, respectively. The species-specific rate constants for Tl+ reacting with individual bromine species were determined and decreased in the order: BrCl > Br2 > BrOCl > Br2O > HOBr. Overall, the presented results refine our knowledge regarding the species-specific reactivity of TI(I) with bromine species and will be useful for further prediction of thallium mobility in chlorinated waters containing bromide.
研究领域:
环境科学
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水处理化学
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DOI
高影响因子
Journal of Environmental Chemical Engineering
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2023
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IF 7.7
Jingxuan Yang,Dongxu Qu,Jue Wang,Yangtao Wu,Lingjun Bu,Yuanxi Huang,Shiqing Zhou
The N-Br bond in monobromoamine (NH 2 Br) can be cleaved by UV irradiation to generate Br • and subsequently HO • , resulting in an advanced oxidation condition (i.e., UV/NH 2 Br). This study investigated the degradation of six contaminants of emerging concern (CECs) in the UV/NH 2 Br process, including the phenolic hydrocarbons phenol and bisphenol A (BPA), the amines aniline and sulfadiazine (SDZ), and the persistent organic pollutants ibuprofen (IBP) and carbamazepine (CBZ). The results showed that UV/NH 2 Br process significantly improved the degradation of CECs following pseudo-first order kinetics, and the degradation of CECs was enhanced with the increase of NH 2 Br dosage. UV/NH 2 Br was more efficient in degrading CECs containing phenolic hydroxyl groups (100 %), followed by those containing amine groups (> 95 %). The degradation efficiency was influenced by the pH value and was highest at pH 7. It was found that low concentrations of Cl − (< 0.5 mM ) and HCO 3 − (< 0.5 mM) promoted the degradation of SDZ and IBP, but further increases in Cl − and HCO 3 − (0.5 ∼ 5.0 mM) resulted in inhibition. SDZ and IBP degradation was inhibited by photo absorption competition and free radical depletion in natural organic matter and actual water. Probe experiments showed that reactive bromine species (RBS), reactive nitrogen species (RNS), and hydroxyl radical (HO • ) played a dominant role in CEC degradation. During the degradation of IBP by UV/NH 2 Br, hydroxylation, bromination , and quinylation were proposed as the primary reaction mechanisms. As compared to HOCl disinfection, NH 2 Cl disinfection after the UV/NH 2 Br process produced lower concentrations of disinfection by-products (DBPs).
研究领域:
环境科学
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化学工程
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产品关联
DOI
高影响因子
FUEL
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2022
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IF 8.035
Defu Yin,Renjie Ji,Jingyun Zhang,Shitao Yu,Lu Li,Shiwei Liu,Long Jiang,Ying Liu,Zhanqian Song,Yue Liu
A core–shell catalyst composed of mCeO 2 shell and Pd metal core was prepared by one-pot wet chemical method and used for the hydrogenation of phenol to cyclohexanone. The phenol conversion and cyclohexanone selectivity were 96.3 % and 95.3 % at reaction conditions of 50 min, 80 °C and 1 MPa H 2 . The effects of Ce species and Br species in the preparation of catalysts was studied, and the synthesis mechanism of core–shell Pd@mCeO 2 catalysts was preliminarily revealed. By discussing the phenol adsorption mechanism and the redox properties of the catalyst, the activation of H 2 by Pd sites and phenol by cerium oxide (CeO 2 ) sites of the surface were studied. H 2 -TPR and XPS characterization were used to explain the effect of Ce species and Br species for the catalytic performance. These results indicated that the electronic structure of Pd was regulated by the interaction between Pd and Ce, and different O sites were generated around the Pd sites. In situ IR spectra indicated that phenol was adsorbed and dissociated on cerium to form phenoxy species and water, this synergistic catalytic pattern of carrier activated substrate and hydrogenation site promoted the hydrogenation of phenol and improved the catalytic efficiency.
研究领域:
催化
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化学工程
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材料科学
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物理化学
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产品关联
DOI
高影响因子
WATER RESEARCH
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2023
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IF 12.8
Meng Zhang,Kunde Lin
Although polyhalogenated carbazoles (PHCZs) have been widely detected in the marine environment, their origin is far from clear. In this study, the formation of PHCZs in the chlorination of seawater containing carbazole and its derivatives was investigated. A total of 14 PHCZs including six commonly found and eight unknown congeners were identified in the chlorination of seawater with carbazole. In addition, this study for the first time demonstrated the production of common PHCZs from the chlorination of seawater with 3-methyl carbazole and 3-formyl carbazole, especially 1,8-dibromo-3,6-dichlorocarbazole from 3-methyl carbazole. The formation of PHCZs in the reaction resulted from the halogenation of carbazole by reactive chlorine species (RCS) and mainly reactive bromine species (RBS), forming from the oxidation of bromide by RCS. Results also indicated that the reaction followed a successive halogenation pattern. A higher content of free chlorine and bromide facilitated the generation of RBS, while a higher concentration of DOC exhibited an inhibitory effect. The effects of free chlorine, bromide, DOC, and temperature on the formation of PHCZs were congener-specific. Given the widespread use of chlorination in seawater disinfection, seawater chlorination might be a potential source of PHCZs in the marine environment.
研究领域:
环境化学
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海洋科学
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水处理
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产品关联
DOI
PubMed
高影响因子
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