Reactive Uptake of N₂O₅ by Aerosols Containing Dicarboxylic Acids. Effect of Particle Phase, Composition, and Nitrate Content

Abstract

Reactive uptake coefficients for loss of N(2)O(5) to micron-size aerosols containing oxalic malonic, succinic, and glutaric acids, and mixtures with ammonium hydrogen sulfate and ammonium sulfate, are presented. The uptake measurements were made using two different systems: atmospheric pressure laminar flow tube reactor (Cambridge) and the Large Indoor Aerosol Chamber at Forschungszentrum Juelich. Generally good agreement is observed for the data recorded using the two techniques. Measured uptake coefficients lie in the range 5 x 10(-4)-3 x 10(-2), dependent on relative humidity, on particle phase, and on particle composition. Uptake to solid particles is generally slow, with observed uptake coefficients less than 1 x 10(-3), while uptake to liquid particles is around an order of magnitude more efficient. These results are rationalized using a numerical model employing explicit treatment of both transport and chemistry. Our results indicate a modest effect of the dicarboxylic acids on uptake and confirm the strong effect of particle phase, liquid water content, and particulate nitrate concentrations.

Amorphous and crystalline aerosol particles interacting with water vapor: conceptual framework and experimental evidence for restructuring, phase transitions and kinetic limitations

“…With regard to unraveling the molecular mechanisms and kinetics of water uptake/evaporation and deliquescence/efflorescence of both amorphous and crystalline particles, we suggest that a clear distinction between surface and bulk processes is important and that relevant information can be obtained by highprecision H-TDMA measurements (including h&d experiments). Besides water uptake, low molecular diffusivity in (semi-)solid amorphous phases may also retard the uptake of gaseous photo-oxidants and the chemical transformation of aerosol particles and components (Smith et al, 2003;Katrib et al, 2005;Pöschl, 2005;Ammann and Pöschl, 2007;Pöschl et al, 2007;McNeill et al, 2008;Griffiths et al, 2009;Hallquist et al, 2009;Pfrang et al, 2009;Shiraiwa et al, 2009). …”

Gas–particle partitioning of atmospheric aerosols: interplay of physical state, non-ideal mixing and morphology

“…48 The presence of organic coatings on aqueous aerosols can suppress heterogeneous N 2 O 5 hydrolysis by providing a barrier through which N 2 O 5 needs to diffuse in order to undergo hydrolysis. [49][50][51] Reactive uptake of O 3 and NH 3 to organic aerosols exhibits a pronounced decrease as RH decreases owing to the phase transformation from viscous liquid to semi-solid or amorphous solid. 16,52 Therefore, the presence of a semi-solid matrix may effectively shield reactive organic compounds from chemical degradation in long-range transport.…”

Heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with airborne TiO<sub>2</sub> particles and its implication for stratospheric particle injection

“…It is well known that the heterogeneous uptake of N 2 O 5 onto particles (including but not limited to minerals) is driven by the solvation of N 2 O 5 (after being accommodated onto the surface) into liquid or adsorbed water in the particles, followed by its hydrolysis to form HNO 3 (Bertram and Thornton, 2009;Griffiths et al, 2009;Tang et al, 2012). The formation of multilayers of adsorbed water on the TiO 2 surface can promote the solvation and hydrolysis of N 2 O 5 onto the surface, and thus increase the uptake coefficient of N 2 O 5 .…”