Date of Thesis
Fall 2025
Description
The COVID-19 pandemic led to an increase in use of disinfectants such as chlorine bleach in indoor environments, which releases hypochlorous acid (HOCl) and chlorine (Cl2) gases when applied to a surface. HOCl and Cl2 can undergo multiphase oxidation and chlorination reactions with olefinic compounds like fatty acids (FAs) that are found on indoor surfaces and human skin. However, the additional components on skin surfaces and in the air could influence the identities of products formed and their formation rates. Due to wildfires and fossil fuel combustion, many people are exposed to combustion-sourced compounds like polycyclic aromatic hydrocarbons (PAHs) and phenolics, which may influence how FAs react with reactive gases. To investigate multicomponent reactions between bleach vapor and FAs, films of oleic acid (OA) with and without PAHs were prepared on glass circle slides that were then placed in a glass flow tube reactor under bleach vapor exposure. Oxidation and chlorination products were characterized using liquid chromatography – mass spectrometry (LC-MS) and relative quantification was performed to compare experimental cases. The effectiveness of the PAH as a photosensitizer in the mixture affected the OA decay rate. At low levels of HOCl/Cl2 exposure, the addition of benzo[a]pyrene to OA films enhanced the formation of dimeric OA esters compared to pure OA films, while the addition of phenanthrene did not. Literature indicates that oxidized PAHs tend to increase the inherent oxidative potential of solutions and surfaces via quinone formation, which we hypothesized would influence OA oxidation to a greater effect than the parent PAHs. Heightened oxidative potential represents a larger volume of reactive oxygen species, yielding additional oxidants in the surface films. Thus, the addition of phenanthrenequinone to the sample was investigated. PhenQuin increased the rate constant of OA decay by roughly 3x more than Phen and pure OA but showed an OA decay rate constant similar to when BaP was added to the surface film. These findings demonstrate that the presence and identity of combustion-sourced compounds modulate the chemical reactivity of a monounsaturated fatty acid under bleach vapor exposure. Oxidized PAHs, like phenanthrenequinone, can enhance secondary oxidant generation within the film and thus fatty acid degradation. PAH influence over OA reactivity highlights the importance of considering complex surface and gas-phase mixtures when evaluating multiphase indoor chemistry because the interaction between certain cleaning agents and pollutants could lead to the formation of unexpected and potentially harmful by-products.
Keywords
Multiphase chemistry, oleic acid, oxidation, bleach vapor, PAHs, mass spectrometry
Access Type
Masters Thesis (Bucknell Access Only)
Degree Type
Master of Science
Major
Chemistry
First Advisor
Dr. Douglas B. Collins
Recommended Citation
Stettler, Lauren, "The Influence of Polycyclic Aromatic Hydrocarbons on the Reactivity of Fatty Acids when Exposed to Chlorine Bleach Vapor" (2025). Master’s Theses. 304.
https://digitalcommons.bucknell.edu/masters_theses/304