Uptake of Ozone to Deliquesced KI and Mixed KI/NaCl Aerosol Particles

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2010-07, Vol.114 (26), p.7085-7093
• Main Authors: Rouvière, Aurélie, Sosedova, Yulia, Ammann, Markus
• Format: Article
• Language: English
• Subjects: A: Atmospheric, Environmental and Green Chemistry
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp103257d

The kinetics of uptake of ozone to deliquesced potassium iodide (KI) aerosol particles has been investigated in an aerosol flow tube at 72−75% relative humidity, room temperature, and atmospheric pressure. The observed loss of ozone was further analyzed in terms of a numeric model to explicitly track the iodide concentration in the particles. This allowed retrieving a value αb = 0.6 ± 0.5 0.4 for the bulk accommodation coefficient (αb). The second order rate constant in the bulk phase agreed with available literature (k b = (1.0 ± 0.3) × 109 M−1 s−1) even for the high ionic strength conditions of the present experiments. As long as iodide remained in excess, the average uptake coefficient was γ = (1.10 ± 0.20) × 10−2. Different experiments were performed where the iodide to chloride ratio, the ozone concentration, and the surface to volume ratio of particles were varied. In combination, the results obtained indicate that uptake was driven by fast bulk accommodation and reaction in the bulk for all conditions investigated. The results further suggest that ozone uptake is not limited by the bulk accommodation coefficient αb under atmospheric conditions.