Date of Award
Union College Only
Bachelor of Science
Andrew J. Huisman
model, particles, ozone, aerosols, chemical
Aerosols are small particles of solid or liquid matter suspended in gas, and are ubiquitous in the atmosphere. They have been implicated in increased human mortality, as well as having a cooling climate effect of roughly half the total warming effects of CO2. Atmospheric aerosols are typically a complex mixture of thousands of different organic and inorganic-species, and as a result studying their physical and chemical processes is notoriously challenging. An ElectroDynamic Balance provides a versatile means of studying aerosols, allowing charged particles to be levitated for several days. Various spectroscopic techniques allow characterization of changes in particle radius and chemical composition in environments similar to the atmosphere. Ozone is a strong oxidant present in parts-per-billion by volume (ppbv) mixing ratios, and is a particularly relevant atmospheric constituent. To quantify ozone concentrations within the balance, an ozone monitor was constructed based on a UV LED and differential absorption measurements across a pair of meter-long absorption cells. This instrument is expected to have a 2 second limit-of-quantitation of roughly 1 ppbv. Since measurements of real particles can occur over many days, it is useful to be able to predict the properties of aerosol particles through computer simulations. The Multiple-component Activity-Dependent Aerosol Model is used to calculate expected changes in radius and chemical composition for up to three component species. This model interfaces with the well-established AIOMFAC model to determine activity coefficients for these components under different conditions to more accurately predict their physical behavior. Model predictions can be compared to experimental results to verify the validity of the model, and thereafter allow rapid screening of aerosol particles that may be interesting to investigate.
Ramphal, Isaac, "Development of an Ozone Monitor and Formulation of a Multiple-Component Activity Dependent Aerosol Model for use with the Union College ElectroDynamic Balance" (2014). Honors Theses and Student Projects. 587.