Kinetics and mechanism of the uptake of N2O5 on mineral dust at 298 K

[摘要] The heterogeneous reaction of N₂O₅ with mineral (Saharan) dust hasbeen studied at T=298 K using a combination of Knudsen and DRIFTS cells forkinetic and product investigations, respectively. The initial uptakecoefficient has been determined to be γ=(8.0±0.3)·10⁻². This uptake slowly saturates into a steady state uptake ofγ=(1.3±0.3)·10⁻² suggesting that reaction ofN₂O₅ with the mineral dust surface and hydrolysis ofN₂O₅ on the surface take place simultaneously. Both uptakecoefficients have been calculated on the basis of the geometric (projected)surface area of the sample and must therefore be regarded as upper limits.In addition, the product investigations show that N₂O₅ isirreversibly taken up to form nitrate on the surface. Recent modelcalculations suggest that the uptake rates of N₂O₅ on Saharan dustwhich we measured may be large enough to influence the photo-oxidant budget of theatmosphere.

[学科分类] 大气科学