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| Titel |
Heterogeneous chemistry of monocarboxylic acids on α-Al2O3 at different relative humidities |
| VerfasserIn |
S. R. Tong, L. Y. Wu, M. F. Ge, W. G. Wang, Z. F. Pu |
| 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 ; 10, no. 16 ; Nr. 10, no. 16 (2010-08-16), S.7561-7574 |
| Datensatznummer |
250008705
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| Publikation (Nr.) |
 copernicus.org/acp-10-7561-2010.pdf |
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| Zusammenfassung |
| A study of the atmospheric heterogeneous reactions of formic acid, acetic
acid, and propionic acid on α-Al2O3 was performed at ambient
condition by using a diffuse reflectance infrared Fourier transform
spectroscopy (DRIFTS) reactor. From the analysis of the spectral features,
observations of carboxylates formation provide strong evidence for an
efficient reactive uptake process. Comparison of the calculated and
experimental vibrational frequencies of adsorbed carboxylates establishes
the bridging coordinated structures on the surface. The uptake coefficients
of formic acid, acetic acid, and propionic acid on α-Al2O3
particles are (2.07±0.26)×10−3 or (2.37±0.30)
×10−7, (5.00±0.69)×10−3
or (5.99±0.78)×10−7, and (3.04±0.63)×10−3 or
(3.03±0.52)×10−7, respectively (using geometric or BET
surface area). Furthermore, the effect of varying relative humidity (RH) on
these heterogeneous reactions was studied. The uptake coefficients of
monocarboxylic acids on α-Al2O3 particles increase initially (RH<20%)
and then decrease with the increased RH (RH>20%) which was
due to the effect of water on carboxylic acid solvation, particle surface
hydroxylation, and competition for reactive sites. On the basis of the
results of experimental simulation, the mechanism of heterogeneous reaction
of α-Al2O3 with carboxylic acids at ambient RH was discussed. The
loss of atmospheric monocarboxylic acids due to reactive uptake on available
mineral dust particles may be competitive with homogeneous loss pathways,
especially in dusty urban and desertified environments. |
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