| |
| author | Zoe Laura CoatesFuentes |
| title | Heterogeneous Uptake of O3 and SO2 on Kaolinite as a Function of Atmospheric Processing |
| abstract |
Mineral dust aerosol, suspended particulates that exist within the atmosphere due primarily to dust storms in arid regions, serve as reactive surfaces for other
atmospheric species, including O3, SO2, and volatile organic compounds (VOCs). Studying the reactivity of these mineral surfaces under
atmospherically relevant conditions is instrumental in developing a comprehensive understanding of the destruction of tropospheric O3, which is closely
related to high levels of pollution. For this study, a laminar flow reactor, coupled with an ozone detector, was used to monitor the O3 uptake on
kaolinite, an aluminosilicate clay, as a function of relative humidity, VOC pre-coating, and simultaneous SO2 reactivity. Steady state reactive uptake
coefficient (𝛾BET,O3) calculations quantified the number of reactive collisions between ozone molecules and the mineral surface at
average dose points of 4,000-10,000 ppb-min. Data show a 75.8-90.2% decrease in 𝛾BET,O3 at higher relative humidity (RH) consistent
with competitive adsorption of water onto the surface. When holding RH constant at 25%, O3 uptake increased by two orders of magnitude for dusts that
have been pre-exposed to limonene and α-pinene, showing an introduction of further reactive sites due to the adsorbed products of these VOCs with the surface.
Furthermore, exposure to SO2 also showed increased uptake of O3 by two orders of magnitude, indicating possible sulfate formation on the
kaolinite surface. Reactivity with α-pinene -processed kaolinite showed that the VOC dominated uptake reactivity, though sustained uptake of SO2
indicated the possible formation of organosulfates. The introduction of greater complexity into the laboratory experiments of O3 on kaolinite provides
more accurate representations of atmospheric chemistry to be used for computational models and eventual policy recommendations. We recommend uptake values of
10-7 for VOC and SO2 processed kaolinite.
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| school | The College of Liberal Arts, Drew University |
| degree | B.A. (2018) |
| advisor | Ryan Hinrichs |
| committee | Maryanne Pearsall
Timothy Carter |
| full text | ZLCoatesFuentes.pdf |
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