Characterizing physicochemical properties of organic aerosol mixtures
Abstract/Contents
- Abstract
- The presence of anthropogenic organic compounds in atmospheric aerosols has the potential to contribute to global climate change by altering the hygroscopic behavior and surface tension of the aerosols. Since the hygroscopicity and surface tension of aerosols are related to their sizes, albedos, and tendencies to form clouds, characterizing these two key parameters is important in understanding the effect of atmospheric aerosols on global climate change. Although real atmospheric aerosols are composed of complex mixtures of inorganic and/or organic compounds, the hygroscopicity and surface tension of various aerosol mixtures are still poorly understood. Laboratory experiments were designed to provide a better understanding of the physicochemical properties of various dicarboxylic acid mixtures. Dicarboxylic acids are frequently measured water-soluble organic compounds in atmospheric aerosols. The major focus was on whether the water uptake or surface tension altering property of one organic solute was affected by the presence of another compound in solution. First, to understand the hygroscopicity of dicarboxylic acid aerosol mixtures, water vapor pressure was measured at 12 °C over aqueous bulk solutions containing dicarboxylic acids using both a quadrupole mass spectrometer and a Baratron pressure transducer. Our water vapor pressure measurements for mixtures were compared with predictions made using Zdanovskii-Stokes-Robinson (ZSR) method and the modified UNIQUAC Functional-group Activity Coefficients (UNIFAC) model. Second, to understand the surface tension of dicarboxylic acid aerosol mixtures, surface tension was measured at 20 °C over dicarboxylic acid solutions using a tensiometer. The surface tension of two-, three-, and four-dicarboxylic acid solutions was measured to see how the overall surface tension depends on the number of dicarboxylic acids added to the solution. Our surface tension measurements were then utilized in Kohler's equation to examine the atmospheric impact of the organic aerosol mixtures. Due to surface tension-lowering effects, aerosols containing organic compounds can be more easily activated into cloud droplets. Lastly, the surface tension of solutions containing dicarboxylic acids plus a second category of water-soluble compounds was measured at 20 °C. Ammonium sulfate, D-glucose, and humic acid sodium salts were chosen to represent other categories of water-soluble compounds. Taken together, our results suggest that the physicochemical properties of organic aerosol mixtures cannot be accurately predicted using a linear combination of single component properties. Instead, the interactions between various components must be included for better predictions of physicochemical properties. More studies are needed to accurately quantify and model aerosol effects on global climate changes.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2013 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Lee, Jae Young |
|---|---|
| Associated with | Stanford University, Department of Civil and Environmental Engineering. |
| Primary advisor | Hildemann, Lynn M. (Lynn Mary) |
| Thesis advisor | Hildemann, Lynn M. (Lynn Mary) |
| Thesis advisor | Jacobson, Mark Z. (Mark Zachary) |
| Thesis advisor | Reinhard, Martin |
| Advisor | Jacobson, Mark Z. (Mark Zachary) |
| Advisor | Reinhard, Martin |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Jae Young Lee. |
|---|---|
| Note | Submitted to the Department of Civil and Environmental Engineering. |
| Thesis | Ph.D. Stanford University 2013 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2013 by Jae young Lee
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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