Atmos. Chem. Phys. Discuss., 11, 3493-3527, 2011
www.atmos-chem-phys-discuss.net/11/3493/2011/
doi:10.5194/acpd-11-3493-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Effects of temperature on the heterogeneous oxidation of sulfur dioxide by ozone on calcium carbonate
L. Y. Wu, S. R. Tong, W. G. Wang, and M. F. Ge
Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, China

Abstract. The heterogeneous oxidations of sulfur dioxide by ozone on CaCO3 were studied as a function of temperature (230 to 298 K) at ambient pressure. Oxidation reactions were followed in real time using diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) to obtain kinetics and mechanistic data. From the analysis of the spectral features, the formation of sulfate was identified on the surface in the presence of O3 and SO2 at different temperatures from 230 to 298 K. The results showed that the heterogeneous oxidations and the rate of sulfate formation were sensitive to temperature. An interesting stage-transition state was observed at temperatures range from 230 to 257 K, but it became ambiguous gradually above 257 K. The reactive uptake coefficients at different temperatures from 230 to 298 K were acquired for the first time, which can be used directly in the model studies to predict the formation of secondary sulfate aerosol in the troposphere. Furthermore, the rate of sulfate formation had a turning point at about 250 K. The sulfate concentration at 250 K was about twice as large as that at 298 K. The rate of sulfate formation increased with decreasing temperature at temperatures above 250 K, while there is a contrary temperature effect at temperatures below 250 K. The activation energy for heterogeneous oxidations at temperatures from 245 K to 230 K was determined to be 14.63 ± 0.20 kJ mol−1. Mechanism of temperature dependence was proposed and the atmospheric implications were discussed.

Citation: Wu, L. Y., Tong, S. R., Wang, W. G., and Ge, M. F.: Effects of temperature on the heterogeneous oxidation of sulfur dioxide by ozone on calcium carbonate, Atmos. Chem. Phys. Discuss., 11, 3493-3527, doi:10.5194/acpd-11-3493-2011, 2011.
 
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