Effects of temperature on the heterogeneous oxidation of sulfur dioxide by ozone on calcium carbonate 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
12 Jul 2011
Received: 17 Jan 2011 – Published in Atmos. Chem. Phys. Discuss.: 31 Jan 2011 Abstract. The heterogeneous oxidation of sulfur dioxide by ozone on CaCO3 was
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
kinetic 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 oxidation and the rate of sulfate
formation were sensitive to temperature. An interesting stage-transition
region was observed at temperatures ranging 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 atmospheric chemistry modeling 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 oxidation
at temperatures from 245 K to 230 K was determined to be 14.63 ± 0.20 kJ mol−1.
A mechanism for the temperature dependence was proposed and the
atmospheric implications were discussed.
Revised: 05 Jul 2011 – Accepted: 07 Jul 2011 – Published: 12 Jul 2011
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., 11, 6593-6605, doi:10.5194/acp-11-6593-2011, 2011.