Student-faculty Team Studying the Impact of New Refrigerants on the Atmosphere
Funded in part by a 2019 Edgren Scholarship, Professor Stacey Stoffregen and Jesse Mojeske ’20 use computational chemistry to model the degradation of substances that have been largely unstudied since they were introduced to the market.
By Monique Kleinhuizen '08, GS'16, new media strategist
July 13, 2020 | 3 p.m.
Professor Stacey Stoffregen and Jesse Mojeske ’20, who've spent two years researching the impact of refrigerants on the environment
“There was a river in Ohio that started on fire in 1952 because it was so polluted.”
That’s the way Professor of Chemistry Stacey Stoffregen captures the state of the environment before the Environmental Protection Agency (EPA) was formed or there was much thought put into the impact of chemicals on the environment. The 1970s brought on an entirely new field of study, green chemistry, focused on finding a way forward in industry in a more environmentally-friendly way.
“For instance, the coils in refrigeration systems used to use chlorofluorocarbons (CFCs). The goal has been to replace freon in refrigeration systems and air-conditioning units with other substances,” Stoffregen explains. A 1974 landmark study linked CFCs to depletion of the ozone layer, and alternative refrigerants have come on the market that are believed to have little or no ozone depletion potential (ODP).
“Hydrofluoroolefins (HFOs), for instance, are promising non-chlorine-containing CFC replacements. They are believed to have relatively short atmospheric lifetimes—on the order of days to weeks—near-zero to zero ODP, limited transport to the stratosphere, and they’re believed to be a sink for HO radical,” she adds. “People are starting to use HFOs, but not a lot of work has been done yet to understand whether they’re entirely safe for the environment. We’re interested in learning what they break down into.”
Over the past two years, Stoffregen and chemistry major Jesse Mojeske ’20 have looked at HFOs, using computational chemistry methods to model how this class of compounds breaks down over time, and their potential impacts on the environment.
“At Bethel, we emphasize the care of creation, being good stewards of God’s creation. How we, as chemists, can do that is by better understanding the materials we’re using before they become globally employed. Before they’ve had a detrimental impact on the environment.”
— Professor of Chemistry Stacey Stoffregen“Aerosols that we used to use were going into the atmosphere and degrading and releasing radicals that would interact with and deplete the ozone,” says Mojeske. “Now for industry, and construction, we’re looking at hydrofluoroolefins. A lot of wet chemistry studies have shown that these have zero ozone depletion potential and low global warming potential.”
“Wet chemistry,” in this case, means simulating atmospheric conditions in a smog chamber. Stoffregen and Mojeske submit quantum mechanical calculations through a virtual private network (VPN) to supercomputers at Hope College in Michigan to model the reactivity of HFOs used in smog chamber studies. Through a grant from the National Science Foundation, schools in the Midwest Undergraduate Computational Chemistry Consortium—including Bethel—have access to processing capabilities that they wouldn’t otherwise have. This is one type of research that’s always done from afar, so COVID-19 hasn’t had as great of an impact as on other areas. Along the way, Mojeske has modeled the molecules in a simulated digital interface to optimize what they would look like and how they would behave. Preliminary results suggest that HFOs have the potential to produce perfluoroalkyl substances (PFAs), a persistent pollutant in groundwater.
“All of that is done through quantum mechanics,” he explains. “In the past, people were just using compounds and not understanding completely how they broke down...now we’re beginning to understand fully what the molecule will do before we claim it to be safe.”
Mojeske’s portion of the research was funded through a summer Edgren Scholarship, and he also earned two credits for it through his junior research project requirement. He presented the work last summer at the Midwest Undergraduate Computational Chemistry Consortium (MU3C) at Ohio State University. The team’s goal is to publish the work in an American Chemical Society journal and use the results to seek additional research funding through a Research in Undergraduate Institutions (RUI) grant from the National Science Foundation. But beyond that, there’s a deeper purpose.
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