[Clearing the Air]
Professor Bert Holmes and his cohort of student researchers may reveal replacements for greenhouse gases and ozone-depleting compounds.
At 3 o’clock on a Friday afternoon in the Rhoades-Robinson Kinetics Lab, students gather casually around Chemistry professor Bert Holmes while he works over a small glass-blowing torch. They’ve scooted their stools near his bench, removed their protective goggles and are chatting idly and laughing over the noises coming from an array of interconnecting glass tubes, glass vessels and hundreds of thousands of dollars in hand-fabricated equipment.
“We’re trying to project our findings to say that if we want to stop a reaction that contributes to greenhouse gases, we should not use certain compounds. There’s a touch of gloom and doom, but it all helps the scientific community learn more about what’s happening in the atmosphere.”
They seem expectant, and no wonder. Professor Holmes isn’t conducting an experiment at the moment. He’s roasting marshmallows two at a time over the flame, placing them between graham crackers and chocolate bars, making s’mores as a TGIF treat for a job well done by his eight student researchers.
S’mores, he explains, can be consumed in this laboratory because the setup is a bit unusual—there are no beakers of liquids or watch glasses of solids that would contaminate the air, only gases contained in high vacuum lines. Thus the Kinetics Lab seems more like an office than a research laboratory.
Taking a break from their usual hefty workload—checking gauges, monitoring instruments, recording data, calculating rate constants of unimolecular reactions of hydrocholorofluorocarbons (HCFCs) in the atmosphere—the students convey a camaraderie gained by working closely for several months. They put in long hours over the summer, conducting basic research that just might help make the air a little cleaner and the products we use a little safer.
“Collaborating is so important in research, and we don’t necessarily come into the project knowing that,” says Mark Deaver ’09 (Chemistry).
Check your chemistry knowledge
What are freons?
Freon-11, trichlorofluoromethane, and Freon-12, dichlorodifluoromethane, were developed in the early 20th century as an alternative to the toxic gases that were used as refrigerants, such as ammonia, chloromethane and sulfur dioxide. In the 1990s, most uses of freon, also called chlorofluorocarbons (CFCs), were phased out due to the negative effects that CFCs have on the earth’s ozone layer. The interim replacements for CFCs are hydrochlorofluorocarbons (HCFCs), but these, too, must be phased out and replacements found.
What are HCFCs?
Hydrochlorofluorocarbons are compounds containing hydrogen, chlorine, fluorine and carbon, found on the second to the last column of the periodic table of the elements. They replaced chlorofluorocarbons (CFCs), which were banned by the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer and were long used to manufacture refrigeration equipment and polymer foams. But the protocol requires that HCFCs be replaced by substances with no ozone-depletion potential by 2030 in developed nations and 2040 in developing ones.
What are HCFCs used for?
Hair spray, bug spray and other substances in aerosol cans
Collaborative research is the forte of Holmes, the UNC Asheville Philip G. Carson Distinguished Professor in the Sciences since 1998 and recipient of the 2007 Distinguished Teacher Award. “While I’m teaching them how to be scientists—taking a question and applying the scientific method to find answers—the students learn to work together to advance the body of knowledge in this area of chemistry. They learn teamwork, responsibility, persistence, how to deal with failure, and other life lessons. You can see that in this lab.”
Holmes’ project also helps advance the university’s strategic goal of becoming the leading undergraduate research institution in the U.S. His current research on the gas-phase chemistry of compounds that contain carbon, hydrogen, halogen and oxygen, known as hydrochlorofluorocarbons, HCFCs, or hydrohaloethers, HHEs, is funded by a three-year $271,000 National Science Foundation grant—the latest in a series of $2.2 million in grants he has won over the last 18 years. About $1.5 million was awarded by the National Science Foundation to enhance the research experience for undergraduates. The study, ongoing for the last nine years, is co-led by Chemistry professor George Heard who directs students calculating rate constants and reaction mechanisms.
“As environmental scientists, we want to know what is going on in the atmosphere,” Heard says. “We’re trying to project our findings to say that if we want to stop a reaction that contributes to greenhouse gases, we should not use certain compounds. There’s a touch of gloom and doom, but it all helps the scientific community learn more about what’s happening in the atmosphere.”
The work has practical, relevant applications because of discoveries over the last 30 years showing that many freons—used in spray cans and fire retardants, for example—deplete the ozone layer. Scientists are looking for replacement compounds, such as the HCFCs or HHEs, and the UNC Asheville project contributes to that process.
“What’s the best fire-retardant to put in fire extinguishers? What might replace the freons or HCFCs in aerosol cans? What happens when halogen ethers used in anesthetics for hospital surgeries are released into the atmosphere? This is where our research might lead,” Holmes says.
Hand-picked by Holmes and Heard, student researchers are deeply concerned about environmental issues. Matthew von Holley ’09, who plans to attend dental school, is working toward finding environmentally friendly compounds to use in anesthetics by the medical community. Specifically, he’s learning how the byproducts of halogen-containing ethers break down in the atmosphere, where currently some 700–1,000 tons of halogen-containing ethers are released annually. “We’re wondering whether halo-ethers can be used in anesthetics for the medical community and whether they can serve as the next generation of HCFCs for spray cans, for example,” von Holley says.
A newcomer to the team, Caroline Parworth ’10 says, “This is interesting to me because I’ve always been concerned about pollution. Now I understand more about it and how it works at the molecular level.”
Much of the research is published in professional journals and presented at national conferences. In August, seniors Anthony Ranieri, Sara Solaka and Juliana Duncan presented their work at the American Chemical Society meeting in Philadelphia. A Laurels Scholar, student-athlete and three-year veteran of the HCFC project, Duncan juggles summer soccer workouts with the research.
A Mathematics and Chemistry major, she found her niche after taking Holmes’ General Chemistry class. “Since I have a close family member who has battled skin cancer, this research and its importance apply directly to my life. It’s allowed me to contribute to the fight against global warming and ozone depletion, learn applicable chemistry, and also learn a great deal about myself.”
That personal development is an important outcome of the research, whether it derives from collaborating on data collection and mathematical computations, or from cooking up an afternoon snack in the lab or sharing pizza at professor Holmes’ home.
“We learn to work together and appreciate the strengths and talents of each individual to make the team succeed,” Holmes says. “This research is teaching in a large sense—it’s not only imparting knowledge and experience in the lab, but also giving students preparation for life."