HONO is the main source of hydroxyl radical (OH) in the atmosphere, and is formed by the reaction of NO₂ on the surface of black carbon. Therefore, the heterogeneous reactions of NO₂ on the surface of black carbon have been attracted scientists in the past years. The uptake coefficients varied 7 orders of magnitude in different research groups. For assessing the importance of the heterogeneous reaction, the results are different when selecting different uptake coefficients. On the basis of a deep analysis of the reaction mechanism of NO₂ with black carbon, the reasons of the discrepancy in uptake coefficients were analyzed according to reaction system, surface properties of black carbon and reaction condition. The results will provide a basis for the selection of uptake coefficients in the model. Contents
1 Introduction
2 Heterogeneous reaction mechanism of NO₂ on the surface of black carbon
2.1 Reactions of NO₂ on the surface of black carbon
2.2 Oxidation-reduction reactions of NO₂ on the surface of black carbon
3 Uptake coefficients of NO₂ on the surface of black carbon
3.1 Effects of the reaction system on uptake coefficients
3.2 Effects of the surface properties of black carbon on uptake coefficients
3.3 Effects of the reaction conditions on uptake coefficients
4 Conclusions and outlook