Kinetics of the uptake of SO₂ on mineral oxides: Improved initial uptake coefficients at 298 K from pulsed Knudsen cell experiments

Abstract

Abstract The uptake of SO 2 on γ‐Fe 2 O 3 , γ‐Al 2 O 3 , and Saharan dust has been studied at T = 298 K using a Knudsen cell reactor operated in a steady‐state as well as in a pulsed mode. The initial uptake coefficients determined in the steady‐state mode have been found to be affected by surface saturation as well as bulk diffusion of SO 2 resulting in an apparent dependence of the initial uptake coefficients on the sample mass of the mineral oxides. However, by operating the Knudsen cell in the pulsed mode with shorter response time, these effects could be suppressed. Initial uptake coefficients of γ ini (Fe 2 O 3 ) = (8.8 ± 0.4) × 10 −2 , γ ini (Al 2 O 3 ) = (7.4 ± 0.9) × 10 −3 , and γ ini (Saharan dust) = (7.6 ± 0.5) × 10 −2 were derived. This suggests that Fe 2 O 3 is an important component in determining the reactivity of mineral dusts. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 242–249, 2006