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| Titel |
Laboratory studies of the aqueous-phase oxidation of polyols: submicron particles vs. bulk aqueous solution |
| VerfasserIn |
K. E. Daumit, A. J. Carrasquillo, J. F. Hunter, J. H. Kroll |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 19 ; Nr. 14, no. 19 (2014-10-14), S.10773-10784 |
| Datensatznummer |
250119097
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| Publikation (Nr.) |
 copernicus.org/acp-14-10773-2014.pdf |
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| Zusammenfassung |
| Oxidation in the atmospheric aqueous phase (cloud droplets and deliquesced
particles) has received recent attention as a potential pathway for the
formation of highly oxidized organic aerosol. Most laboratory studies of
aqueous-phase oxidation, however, are carried out in bulk solutions rather
than aqueous droplets. Here we describe experiments in which aqueous
oxidation of polyols (water-soluble species with chemical formula
CnH2n+2On) is carried out within submicron particles in an
environmental chamber, allowing for significant gas–particle partitioning of
reactants, intermediates, and products. Dark Fenton chemistry is used as a
source of hydroxyl radicals, and oxidation is monitored using a
high-resolution aerosol mass spectrometer (AMS). Aqueous oxidation is rapid,
and results in the formation of particulate oxalate; this is accompanied by
substantial loss of carbon to the gas phase, indicating the formation of
volatile products. Results are compared to those from analogous oxidation
reactions carried out in bulk solution. The bulk-phase chemistry is similar
to that in the particles, but with substantially less carbon loss. This is
likely due to differences in partitioning of early-generation products,
which evaporate out of the aqueous phase under chamber conditions (in which
liquid water content is low), but remain in solution for further aqueous
processing in the bulk phase. This work suggests that the product
distributions from oxidation in aqueous aerosol may be substantially
different from those in bulk oxidation experiments. This highlights the need
for aqueous oxidation studies to be carried out under atmospherically
relevant partitioning conditions, with liquid water contents mimicking those
of cloud droplets or aqueous aerosol. |
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