Modeling the Time-Dependent O3 Uptake on a Methane Flame Soot Coating Under Conditions of Competitive O3/NO2 and O3/N2O5 Adsorption

• Published in: Russian journal of physical chemistry. B 2023-02, Vol.17 (1), p.234-243
• Main Authors: Zelenov, V. V., Aparina, E. V.
• Format: Article
• Language: English
• Subjects: Adsorption; Chemical Physics of Atmospheric Phenomena; Chemistry; Chemistry and Materials Science; Industrial areas; Mathematical models; Methane; Nitrogen dioxide; Ozone; Parameters; Physical Chemistry; Reaction products; Soot; Surface chemistry; Time dependence
• ISSN: 1990-7931; 1990-7923
• DOI: 10.1134/S1990793123010141

The uptake of O 3 (1 × 10 12 –5× 10 13 cm −3 ) on a methane soot coating preliminarily exposed to N 2 O 5 , is studied using a flow reactor with a movable insert. Based on the dependence of the ozone uptake coefficient on the exposure time and O 3 concentration, the uptake mechanism is established and a number of elementary parameters are obtained that describe the uptake process at arbitrary O 3 concentrations. Based on the Langmuir representation of adsorption, a model description of the uptake on soot under conditions of the competitive adsorption of O 3 /NO x , where NO x = NO 2 and N 2 O 5 , taking into account the multistage uptake process, is proposed. Based on the developed model and elementary parameters describing the uptake of O 3 , NO 2 , and N 2 O 5 on a fresh soot surface, as well as the uptake of ozone on a surface pretreated with NO 2 and N 2 O 5 , numerical estimates were made of the additional contributions to the ozone uptake for two real scenarios of the O 3 /NO x ratio. For an industrial region in winter, when the ozone concentration is minimal (10 ppb O 3 , 17 ppb NO 2 , and 4 ppb N 2 O 5 ), the additional integral contribution to the uptake of O 3 on the reaction products of NO 2 with soot is 68%, and in the case of N 2 O 5 , it is 3.6%. For the same region in summer, at the maximum ozone concentration (36 ppb O 3 , 17 ppb NO 2 , and 4 ppb N 2 O 5 ), the analogous contributions will be 20 and 1%, respectively. The reasons for this difference are discussed.