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Peroxyl radicals from diketones enhanced the indirect photochemical transformation of carbamazepine: Kinetics, mechanisms, and products.
- Source :
-
Water research [Water Res] 2022 Jun 15; Vol. 217, pp. 118424. Date of Electronic Publication: 2022 Apr 06. - Publication Year :
- 2022
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Abstract
- In surface waters, photogenerated transients (e.g., hydroxyl radicals, carbonate radicals, singlet oxygen and the triplet states of dissolved organic matter) are known to play a role in the transformation of biorecalcitrant carbamazepine (CBZ). Small diketones, such as acetylacetone (AcAc) and butanedione (BD), are naturally abundant and have been proven to be effective precursors of carbon and oxygen centered radicals. However, the photochemical kinetics and mechanisms of coexisting diketones and CBZ are barely known. Herein, the effects of AcAc and BD on the photochemical conversion of CBZ were investigated compared with H <subscript>2</subscript> O <subscript>2</subscript> which was the main ·OH precursor in the environment. An enhancing effect was observed for the degradation of CBZ by the addition of diketones. The enhancing effect of diketones was pH-dependent and much more significant than H <subscript>2</subscript> O <subscript>2</subscript> under simulated solar irradiation. On the basis of the identification of transient species and the competition kinetic model, organic peroxyl radicals were found to play a dominant role in CBZ photodegradation, and the second-order rate constants of the reaction between CBZ and peroxyl radicals were determined to be approximately 10 <superscript>7</superscript> -10 <superscript>8</superscript>  M <superscript>-1</superscript> s <superscript>-1</superscript> . Furthermore, mutagenic acridine was found to be the major cumulative intermediate with a yield of > 30% in the presence of diketones, which might be an environmental concern. This work indicates that the coexistence of diketones and persistent organic pollutants might lead to some detrimental effects on aquatic environments if the water is exposed to sunlight.<br /> (Copyright © 2022 Elsevier Ltd. All rights reserved.)
Details
- Language :
- English
- ISSN :
- 1879-2448
- Volume :
- 217
- Database :
- MEDLINE
- Journal :
- Water research
- Publication Type :
- Academic Journal
- Accession number :
- 35429883
- Full Text :
- https://doi.org/10.1016/j.watres.2022.118424