Reactive uptake of ozone on mineral oxides and mineral dusts

• Published in: Atmospheric environment (1994) 2003-07, Vol.37 (23), p.3201-3211
• Main Authors: Michel, A.E., Usher, C.R., Grassian, V.H.
• Format: Article
• Language: English
• Subjects: Applied sciences; Atmospheric pollution; Catalytic decomposition; Exact sciences and technology; Heterogeneous reactions; Kinetics; Knudsen cell; Mineral aerosol; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Tropospheric ozone
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/S1352-2310(03)00319-4

A Knudsen cell apparatus was used to measure the heterogeneous reactive uptake of ozone on mineral oxide powders at 296 K. Commercially available powders including α-Al 2O 3, α-Fe 2O 3, SiO 2 and kaolinite were investigated as well as two different authentic mineral dusts, China loess and Saharan sand. Initial reactive uptake coefficients, γ o,BET, for the purchased powders were measured as 1.2±0.4×10 −4 for α-Al 2O 3, 2.0±0.3×10 −4 for α-Fe 2O 3, 6.3±0.9×10 −5 for SiO 2 and 3±1×10 −5 for kaolinite. Authentic dust samples were found to have γ ο,BET values of 2.7±0.8×10 −5 for China loess and 6±2×10 −5 for ground Saharan sand. Pressure dependence studies of this reaction on α-Al 2O 3 and α-Fe 2O 3 suggest that the initial uptake of ozone on these mineral oxides is a first-order process. Furthermore, under conditions of this study, these powders exhibit catalytic behavior toward the decomposition of ozone, and have turnover rates greater than one. Additionally, the reactive uptake of ozone on α-Al 2O 3 showed a small temperature dependence over a range of temperatures from 250 to 330 K, consistent with reports of low energies of activation (∼5–10 kJ mol −1) for ozone destruction on oxide powders.