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| Titel |
Ozone decomposition kinetics on alumina: effects of ozone partial pressure, relative humidity and repeated oxidation cycles |
| VerfasserIn |
R. C. Sullivan, T. Thornberry, J. P. D. Abbatt |
| 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 ; 4, no. 5 ; Nr. 4, no. 5 (2004-08-23), S.1301-1310 |
| Datensatznummer |
250001941
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| Publikation (Nr.) |
 copernicus.org/acp-4-1301-2004.pdf |
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| Zusammenfassung |
| The room temperature kinetics of gas-phase ozone loss via heterogeneous
interactions with thin alumina films has been studied in real-time using 254nm
absorption spectroscopy to monitor ozone concentrations. The films were
prepared from dispersions of fine alumina powder in methanol and their
surface areas were determined by an in situ procedure using adsorption of krypton at
77K. The alumina was found to lose reactivity with increasing ozone
exposure. However, some of the lost reactivity could be recovered over
timescales of days in an environment free of water, ozone and carbon
dioxide. From multiple exposures of ozone to the same film, it was found
that the number of active sites is large, greater than 1.4x1014
active sites per cm2 of surface area or comparable to the total number
of surface sites. The films maintain some reactivity at this point, which is
consistent with there being some degree of active site regeneration during
the experiment and with ozone loss being catalytic to some degree. The
initial uptake coefficients on fresh films were found to be inversely
dependent on the ozone concentration, varying from roughly 10-6 for
ozone concentrations of 1014 molecules/cm3 to 10-5 at
1013 molecules/cm3. The initial uptake coefficients were not
dependent on the relative humidity, up to 75%, within the precision of
the experiment. The reaction mechanism is discussed, as well as the
implications these results have for assessing the effect of mineral dust on
atmospheric oxidant levels. |
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