DRIFTS and Knudsen cell study of the heterogeneous reactivity of SO2 and NO2 on mineral dust M. Ullerstam1, M. S. Johnson2, R. Vogt3, and E. Ljungström1 1Gothenburg University, Department of Chemistry, SE-41296 Gothenburg, Sweden 2Copenhagen University, Department of Chemistry, Universitetsparken 5, DK-2100 Copenhagen, Denmark 3Ford Forschungszentrum GmbH Aachen, Süsterfeldstrasse 200, D-52072 Aachen, Germanyhagen
Abstract. The heterogeneous oxidation of
SO2 by NO2 on mineral dust was studied using Diffuse
Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and a Knudsen cell. This
made it possible to characterise, kinetically, both the formation of sulfate and nitrate as
surface products and the gas phase loss of the reactive species. The gas phase loss rate was
determined to be first order in both SO2 and
NO2. From the DRIFTS experiment the uptake
coefficient, g, for the formation of sulfate was determined to be of the order of
10-10 using the BET area as the reactive surface area. No significant formation of sulfate was seen in the
absence of NO2. The Knudsen cell study gave uptake coefficients of the order of
10-6 and 10-7 for SO2 and
NO2 respectively. There was no significant difference in uptake when
NO2 were introduced individually compared to experiments in which
present at the same time.
Citation: Ullerstam, M., Johnson, M. S., Vogt, R., and Ljungström, E.: DRIFTS and Knudsen cell study of the heterogeneous reactivity of SO2 and NO2 on mineral dust, Atmos. Chem. Phys., 3, 2043-2051, doi:10.5194/acp-3-2043-2003, 2003.