Volatility-Driven Bimodal Particle Size Distributions in Succinic Acid and Ammonium Sulfate Aerosols
Date of Thesis
Spring 2026
Description
Due to their abundance in atmospheric aerosols, ammonium sulfate (AS) and succinic acid (SA) are commonly studied in the field of atmospheric chemistry and physics as they are representative of organic compounds and inorganic salts in the atmosphere, respectively. To study these aerosols in laboratory settings, they are often generated via a technique known as atomization. Aerosols produced in this way are expected to have a lognormal size distribution, often measured with a scanning mobility particle sizer (SMPS). However, in specific mixtures of AS and SA, bimodal size distributions have been observed; this deviates greatly from expected behavior. Understanding the size distribution of aerosols, particularly of two compounds commonly found in the atmosphere, is critical for characterizing their interactions in the atmosphere and has important implications in areas such as climate and human health. This thesis focuses on better characterizing AS/SA aerosols and working towards developing an explanation of their bimodal particle size distribution. One proposed hypothesis that the bimodal particle size distribution is due to polymorphism of SA was investigated with powder X-ray diffraction (PXRD), but ultimately rejected. Another proposed hypothesis was that the bimodal particle size distribution is due to enhanced volatility of SA in the presence of AS, primarily through interactions with the charged groups of AS. Thermogravimetric analysis (TGA) showed that aqueous solutions of mixed AS/SA have higher volatility than either compound alone. TGA data, as well as a population balance model simulation, show enhanced volatility of SA is a plausible explanation for the unusual behavior of AS/SA aerosols.
Keywords
atmospheric, aerosols, chemistry, volatility, model, population balance equation
Access Type
Honors Thesis
Degree Type
Bachelor of Science in Chemical Engineering
Major
Chemical Engineering
Minor, Emphasis, or Concentration
Chemistry
First Advisor
Ryan Snyder
Second Advisor
Dabrina Dutcher
Third Advisor
Tim Raymond
Recommended Citation
Feldscher, Will, "Volatility-Driven Bimodal Particle Size Distributions in Succinic Acid and Ammonium Sulfate Aerosols" (2026). Honors Theses. 779.
https://digitalcommons.bucknell.edu/honors_theses/779