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| Titel |
The effects of nitrate on the heterogeneous uptake of sulfur dioxide on hematite |
| VerfasserIn |
L. D. Kong, X. Zhao, Z. Y. Sun, Y. W. Yang, H. B. Fu, S. C. Zhang, T. T. Cheng, X. Yang, L. Wang, J. M. Chen |
| 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. 17 ; Nr. 14, no. 17 (2014-09-10), S.9451-9467 |
| Datensatznummer |
250119021
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| Publikation (Nr.) |
 copernicus.org/acp-14-9451-2014.pdf |
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| Zusammenfassung |
| Nitrate is often found to be associated with atmospheric
particles. Surface nitrate can change the hygroscopicity of these particles,
and thus impact their chemical reactivity. However, the influence of nitrate
on heterogeneous reactions of atmospheric trace gases is poorly understood.
In this work, the effects of nitrate on heterogeneous conversion of SO2
with hematite at 298 K are investigated using an in situ diffuse reflectance
infrared Fourier transform spectroscopy (DRIFTS) and a White cell coupled
with Fourier transform infrared spectroscopy (White cell-FTIR). It is found
that nitrate participates in heterogeneous reactions of SO2,
accelerates the formation rate of sulfate, and leads to the formation of
surface-adsorbed HNO3 and gas-phase N2O and HONO. The results
indicate that low to moderate amounts of nitrate significantly enhance the
reactivity of hematite–nitrate mixtures, the uptake of SO2, and the
formation of sulfate on hematite. For mixtures, the sample containing 24%
nitrate exhibits the highest sulfate formation rate, and its corresponding
uptake coefficient calculated by geometric surface area is about 5.5 times
higher than that of hematite alone. The sample containing 48% nitrate
presents the highest Brunauer–Emmett–Teller (BET) uptake coefficient, and the value is about 8 times
higher than that of pure hematite. No uptake of SO2 and formation of
sulfate are observed on pure nitrate. Evidence presented herein implies a
significant contribution of the unreleased HNO3 and HONO in the
particles for the conversion of SO2 and the enhanced formation of
sulfate in the atmosphere. A possible mechanism for the influence of nitrate
on the heterogeneous conversion of SO2 on hematite is proposed, and
atmospheric implications based on these results are discussed. |
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