Date of Award

December 2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Alena A. Kubatova

Second Advisor

Evguenii E. Kozliak

Abstract

Two projects are presented in this work:

First, Per- and polyfluoroalkyl substances (PFAS) are synthetic fluorinated organic chemicals, which have been widely used in many consumer products. While some PFAS, like perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), have been restricted due to their negative impacts on human health and the environment, the issue remains a global concern because there are thousands of other PFAS chemicals still in use. In this work, we report the detection of phthalates and volatile PFAS in building materials, identified through an optimized thermal extraction protocol; evolved gas analysis-mass spectrometry (EGA-MS) and thermal desorption-pyrolysis-gas chromatography with mass spectrometry (TD-Pyr-GC-MS). EGA-MS was used for thermal profiling of the materials, differentiating volatilization, i.e., thermal desorption, and thermal decomposition via pyrolysis. Several tested materials showed the occurrence of PFAS related ions at the TD step (150–300 °C) and Pyr step (300–400 °C), suggesting the presence of PFAS. Multi-step temperature programs for TD-Pyr-GC-MS were then developed based on EGA-MS screening. The TD-Pyr-GC-MS results showed detection of perfluoroheptene in all samples at the TD step except for the outer layer of fiberglass analyzed. One metal frame was found to contain PVDF (polyvinylidene fluoride), a fluoropolymer. All window screen samples were found to contain phthalates, a class of plasticizers known for adverse environmental and human health effects. EGA-MS and TD-Pyr-GC-MS proved effective for rapid screening and simultaneous determination of volatile, semi-volatile, and non-volatile chemicals of concern, including PFAS, in complex environmental matrices.

Second project: Due to increasingly strict regulations on exhaust emissions from road traffic, their contribution to the total emissions has decreased in urban areas. In contrast, non-exhaust emissions such as those from vehicle brake pads are less regulated yet make up a proportion of total road traffic emissions in urban areas. To characterize the thermal evolution and breakdown profiles of six representative vehicle brake pads, this research employed evolved gas analysis-mass spectrometry (EGA-MS) and thermal desorption–pyrolysis–gas chromatography with mass spectrometry (TD-Pyr-GC-MS). The EGA-MS results yielded thermal profiles of evolving species, revealing threshold temperature in these materials with thermal breakdown typically occurring between 200 and 750 °C. Furthermore, profiles of selected ions obtained with MS enable early prediction of evolving species. Applying the identified temperatures to TD-Pyr-GC-MS analysis, we identified aromatics, nitrogen-containing compounds, polycyclic aromatic hydrocarbons (PAHs), phthalate, sulfur-containing compounds, and oxygenates evolving within the TD step. The Pyr step revealed the presence of nitrogen-containing compounds, aromatics, alkenes, alkenes, alkanes and oxygenates. With braking temperatures usually between 100 and 500 °C, the results suggest that brake pad emissions contribute to global emissions through the release of VOCs and particulate matter (PM) into the atmosphere, formation of secondary organic aerosol (SOA) formation or the dispersal of contaminating brake dust into soil and water. Although some of these compounds may not be of immediate concern, they can further contribute to the formation of other chemicals, such as disinfectant by-products (DBPs) by serving as precursors. More strict non-exhaust emission controls and the development of high-performance brake pads that reduce environmental and health risks are therefore desirable.

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