Date of Award
Spring 6-13-2025
Document Type
Dissertation
Degree Name
Ph.D. in Chemistry and Biochemistry
Organizational Unit
College of Natural Science and Mathematics, Chemistry and Biochemistry
First Advisor
Brian J. Majestic
Second Advisor
John A. Huffman
Third Advisor
Brady T. Worrell
Fourth Advisor
Sandra S. Eaton
Copyright Statement / License for Reuse
All Rights Reserved.
Keywords
Quinones, Atmospheric aging, Environmentally persistent free radicals, Photooxidation, Photosensitizers, Polycyclic aromatic hydrocarbons, Reactive oxygen species
Abstract
Quinones are ubiquitous species that can be produced from the photochemical aging of combustion-derived particles (CDPs). Polycyclic aromatic hydrocarbons (PAHs) are a major component of CDPs and are precursors to quinones and other oxidized products (OPAHs). My work first expanded on the PAH and OPAH photochemistry research of Dr. John Haynes, who showed that anthracene (ANT) oxidizes into 1,4-naphthoquinone (1,4-NAPQ), 1,4-anthraquinone (1,4-ANTQ), and 9,10-anthraquinone (9,10-ANTQ), and of Dr. Heather Runberg, who demonstrated the ability of ANT and these quinones to generate reactive oxygen species (ROS). Then at the Pacific Northwest National Laboratory (PNNL), I was given the opportunity to investigate the molecular reasons behind the photochemistry as well as the ice nucleation (IN) of biomass burning particles (BBPs).
My work first showed that upon photochemical aging, environmentally persistent free radicals (EPFRs) are formed from PAHs and some OPAHs (e.g., 1,4-NAPQ). However, EPFRs were already present in 1,4-ANTQ and 9,10-ANTQ prior to aging and showed no changes in quantity or speciation after being photoaged. 9,10-ANTQ was particularly stable. In a separate photoaging experiment with 9,10-ANTQ, the quinone did not degrade into any other products, yet it was shown to generate ROS photocatalytically upon entering into its triplet state as an EPFR (39,10-ANTQ*). 1,4-NAPQ and 1,4-ANTQ, on the other hand, underwent photodegradation into other products. One of these products was identified as juglone, a hydroxyquinone, which was also found to generate ROS photocatalytically.
Finally, my work at PNNL showed that BBPs may contain ANT, 9,10-ANTQ, and likely other quinones and hydroxyquinones, which can undergo various aging pathways in the atmosphere, including those proposed in my dissertation. Combustion temperature and biomass source (e.g., tree bark and tree needles) can influence the molecular composition of BBPs, as shown by the differences in the molecular composition between raw pine and pine needle BBPs, which were studied during my time at PNNL. These molecular differences ultimately affect their photochemical behavior and their ability to act as ice nucleating particles in the atmosphere. Overall, my work has demonstrated the significance of quinones in the atmosphere and their role in the environmental fates of CDPs.
Copyright Date
6-2025
Publication Statement
Copyright is held by the author. User is responsible for all copyright compliance.
Rights Holder
Desiree J. Sarmiento
Provenance
Received from ProQuest
File Format
application/pdf
Language
English (eng)
Extent
202 pgs
File Size
3.6 MB
Recommended Citation
Sarmiento, Desiree J., "Photochemistry of Quinones and Combustion-derived Particles" (2025). Electronic Theses and Dissertations. 2595.
https://digitalcommons.du.edu/etd/2595