Effect of Aerosol Acidity and Relative Humidity on Fine Particulate Matter (PM2.5) Formation from the Atmospheric Oxidation of 2-Methyl-3-Buten-2-ol (MBO) (2016)
Undergraduates: Vineet Gopinathan, Tianqu Cui
Faculty Advisor: Jason Surratt
Department: Health Environmental Sciences & Engineering
PM2.5 (aerosol with aerodynamic diameters less than or equal to 2.5 micrometers) has been classified by the Environmental Protection Agency (EPA) as an important air pollutant to regulate due to its links to human illness and climate change. Current research shows that the atmospheric oxidation of 2-methyl-3-buten-2-ol (232-MBO), a volatile organic compound (VOC) emitted from trees, leads to the formation of PM2.5 in the presence of anthropogenic pollutants. The goal of the work was to resolve the exact chemical formation mechanism of secondary organic aerosol (SOA), which is a type of PM2.5, derived from MBO ozonolysis in the presence of acidic sulfate aerosol. Experiments were conducted using a 10-m3 Teflon smog chamber. SOA products were characterized at the molecular level by using gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry equipped with electrospray ionization (LC/ESI-MS). Furthermore, total organic peroxide content of these SOA were determined using an iodometeric spectroscopic method. Preliminary results indicate that the presence of acidic sulfate aerosol doubled the SOA mass loadings compared to neutral sulfate aerosol. Characterization of the SOA at the molecular level revealed the formation 2-methylerythritol and 2-dihydroxyisopentanol, which might serve as potential tracer (marker) compounds for this type of SOA in PM2.5 collected from field studies.