Uptake of NO2 to Deliquesced Dihydroxybenzoate Aerosol Particles

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2009-10, Vol.113 (41), p.10979-10987
• Main Authors: Sosedova, Yulia, Rouvière, Aurélie, Gäggeler, Heinz W, Ammann, Markus
• Format: Article
• Language: English
• Subjects: A: Atmospheric, Environmental and Green Chemistry
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp9050462

The uptake of nitrogen dioxide (NO2), a major trace gas in the atmosphere, to deliquesced particles containing the sodium salts of hydroquinone (1,4-dihydroxybenzene) or gentisic (2,5-dihydroxybenzoic) acid was investigated at 40% relative humidity and 23 °C in an aerosol flow tube. The experiments were performed using the short-lived radioactive tracer 13N and a denuder technique. The observed uptake coefficient for NO2 was up to ∼6 × 10−3 for the hydroquinone disodium salt aerosol, which exceeds previously reported data in the range 10−4 to 10−3. The measured time dependence of NO2 uptake was fitted using a kinetic model taking into account reactant consumption in the particle phase, and keeping the bulk accommodation coefficient, αb, and the rate constants for the reaction of dissolved NO2 with the deprotonated forms of the mentioned phenolic compounds as variables. We obtained αb = 0.024−0.003 +0.018 as a best estimate. For gentisic acid, the second-order rate constant was k 2 = (2.9 ± 0.1) × 108 L mol−1 s−1 and is reported for the first time. The data are consistent with bulk reaction limited uptake, without indications for a surface component in the kinetics.