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Download fileKinetics and Product Formation during the Photooxidation of Butanol on Atmospheric Mineral Dust
journal contribution
posted on 29.03.2018, 00:00 authored by Milena Ponczek, Christian GeorgeMineral
dust particles have photochemical properties that can promote
heterogeneous reactions on their surfaces and therefore alter atmospheric
composition. Even though dust photocatalytic nature has received significant
attention recently, most studies have focused on inorganic trace gases.
Here, we investigated how light changes the chemical interactions
between butanol and Arizona test dust, a proxy for mineral dust, under
atmospheric conditions. Butanol uptake kinetics were measured, exploring
the effects of UV light irradiation intensity (0–1.4 mW/cm2), relative humidity (0–10%), temperature (283–298
K), and butanol initial concentration (20–55 ppb). The composition
of the gas phase was monitored by a high-resolution proton-transfer-reaction
mass spectrometer (PTR-ToF-MS) operating in H3O+ mode. Water was observed to play a significant role, initially reducing
heterogeneous processing of butanol but enhancing reaction rates once
it evaporated. Gas phase products were identified, showing that surface
reactions of adsorbed butanol led to the emission of a variety of
carbonyl containing compounds. Under actinic light these compounds
will photolyze and produce hydroxyl radicals, changing dust processing
from a sink of VOC into a source of reactive compounds.
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Keywords
reactive compoundsButanol uptake kineticsreaction rateshydroxyl radicalsdust processingProduct Formationlight changesH 3 OVOCUVgas phaseAtmospheric Mineral Dust Mineral dust particlesArizona test dustchemical interactionsbutanolsurface reactionsproton-transfer-reaction mass spectrometergas phase productsactinic lightmineral dustdust photocatalytic naturetrace gases