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Measurement report: Rapid oxidation of phenolic compounds by O3 and HO•: effects of air-water interface and mineral dust in tropospheric chemical processes.
- Source :
- EGUsphere; 2/6/2024, p1-48, 48p
- Publication Year :
- 2024
-
Abstract
- Environmental media affect the atmospheric oxidation processes of phenolic compounds (PhCs) released from biomass burning in the troposphere. Phenol (Ph), 4-hydroxybenzaldehyde (4-HBA), and vanillin (VL) are chosen as model compounds to investigate their reaction mechanism and kinetics at the air-water (A-W) interface, on TiO<subscript>2</subscript> clusters, in the gas phase, and in bulk water using a combination of molecular dynamics simulation and quantum chemical calculations. Of them, Ph was the most reactive one. The occurrence percentages of Ph, 4-HBA, and VL staying at the A-W interface are ~72 %, ~68 %, and ~73 %, respectively. As the size of (TiO<subscript>2</subscript>)<subscript>n</subscript> clusters increases, the adsorption capacity decreases until n > 4, and beyond this, the capacity remains stable. A-W interface and TiO<subscript>2</subscript> clusters facilitate Ph and VL reactions initiated by the O<subscript>3</subscript> and HO<superscript>•</superscript>, respectively. However, oxidation reactions of 4-HBA are little affected by environmental media because of its electron-withdrawing group. The O<subscript>3</subscript>- and HO•-initiated reaction rate constant (k) values follow the order of Ph<subscript>A-W</subscript> > VL<subscript>TiO<subscript>2</subscript></subscript> > VL<subscript>A-W</subscript> > 4-HBA<subscript>A-W</subscript> > 4-HBA<subscript>TiO<subscript>2</subscript></subscript> > Ph<subscript>TiO<subscript>2</subscript></subscript> and VL<subscript>TiO<subscript>2</subscript></subscript> > Ph<subscript>A-W</subscript> > VL<subscript>A-W</subscript> > 4-HBA<subscript>TiO<subscript>2</subscript></subscript> > Ph<subscript>TiO<subscript>2</subscript></subscript> > 4-HBA<subscript>A-W</subscript>, respectively. Some byproducts are more harmful than their parent compounds, so should be given special attention. This work provides key evidence for the rapid oxidation observed in the O<subscript>3</subscript>/HO<superscript>•</superscript> + PhCs experiments at the A-W interface. More importantly, differences in oxidation of PhCs by different environmental media due to the impact of substituent groups were also identified. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- Database :
- Complementary Index
- Journal :
- EGUsphere
- Publication Type :
- Academic Journal
- Accession number :
- 175280627
- Full Text :
- https://doi.org/10.5194/egusphere-2023-2856