Mineral aerosol represents one of the largest mass fractions of the global aerosols. Iron oxide is a component of mineral dust in the atmosphere that exists in different forms. In addition, these minerals are found in bacteria, insects, weathered soils, clays, rocks, and urban surfaces. We investigated the uptake of nitrogen dioxide onto several different iron oxides as there are both high concentrations of nitrogen dioxide and iron-containing surfaces present in polluted areas. Our data shows that the uptake of nitrogen dioxide on iron oxide surfaces generates nitrous acid, which is an important precursor for hydroxyl radicals in polluted environment. The kinetics of nitrogen dioxide uptake on iron oxide surface was studied using a coated-wall flow tube coupled to a chemical ionization mass spectrometer. Our results show that the uptake kinetics exhibit an inverse dependence on nitrogen dioxide concentration and follows the Langmuir-Hinshelwood mechanism, where reactivity depends on several variables, including the relative humidity of the carrier gas and the type of iron oxide mineral acting as the substrate. The mechanism of HONO formation on these surfaces are discussed along with their implications for atmospheric chemistry.

Investigation of the conversion of nitrogen dioxide to nitrous acid on iron oxide surfaces

248th National Meeting (2014)

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