Date of Thesis

Spring 2020

Description

Researchers within the aerosol community are currently having a difficult time comparing results and conclusions between groups about the effects of precursor gas concentration on the hygroscopicity of resulting aerosol particles due to varying testing methods. Differences in experimental methods and equipment used can lead to difficulty determining the sources of variation. To resolve this, I tested a range of concentration combinations of α-pinene and ozone to measure the newly formed secondary organic aerosol particle’s affinity towards water. α -pinene is commonly used in similar studies due to its non-toxic properties and its structural similarities to other compounds in the monoterpene class. Concentrations of each varied from 25-200 ppb, and were reacted and allowed to nucleate in a 1 m3 Teflon chamber. Software created within Bucknell University efficiently calculated kappa values for each data set using kappa-Köhler theory and recorded data from a Scanning Mobility Particle Sizer (SMPS) and Cloud Condensation Nuclei Counter (CCNC). We found that high concentrations of semi-volatile organic compounds (SVOCs) and relatively low concentrations of ozone resulted in particles that exhibited greater hygroscopic activity. This behavior is likely due to the excess of α-pinene, leading to a higher probability of becoming oxidized and a larger hygroscopicity. Results from statistical analysis (primarily ANOVA testing) generated confidence in the data produced and conclusions reached by the method used. Further testing should be done with concentrations of each extending beyond the bounds of this study. Using this data, researchers can use the team’s results as a benchmark for comparison between research groups.

Keywords

kappa, CCN, dp50

Access Type

Honors Thesis (Bucknell Access Only)

Degree Type

Bachelor of Science in Chemical Engineering

Major

Chemical Engineering

Minor, Emphasis, or Concentration

Philosophy

First Advisor

Dabrina Dutcher

Second Advisor

Tim Raymond

Third Advisor

Margot Vigeant

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