Mercer Times

The class of chemicals known as PFAS — used in firefighting foams, some nonstick cookware, and many other products — can resist heat and repel water. Their chemical bonds are hard to break, and they persist in water sources for decades. Exposure to them has been associated with cancers, "impacts to the liver and heart, and immune and developmental damage to infants and children," according to the Environmental Protection Agency (EPA), which this month set national limits for PFAS in drinking water.

For her Princeton senior thesis research, Amélie Lemay crafted computer simulations that could one day help lead the way to removing PFAS pollution from the environment. Lemay, a civil and environmental engineering major, used simulations to investigate how seven types of molecules behave above bodies of water, where the water meets the air. She modeled their tendencies to mix with water or stick to the water-air boundary and probed how mixtures of PFAS molecules interact — mimicking the messy reality of contaminated water.

Detailed knowledge of this chemistry could be key to understanding how remediation methods will work in settings like water treatment plants. Over the next few years, utilities across the United States will need to find effective ways to remove PFAS (per- and polyfluoroalkyl substances) from drinking water to comply with EPA limits.

"Most of our drinking water treatment plants are not set up to deal with these compounds," said Lemay. "This type of research can eventually lead to better ways to be able to take PFAS out of water."

Lemay, of Wynnewood, Pennsylvania, came to Princeton with aspirations of using engineering to address environmental challenges. But using computer simulations to understand pollution was not part of her plan.

The summer after her first year, in 2021, Lemay secured internship support from Princeton’s High Meadows Environmental Institute to conduct fieldwork with associate professor Ian Bourg on how rocks weather in the Princeton area and in the French Alps — research with implications for soil nutrients and atmospheric CO2 forecasting.

But COVID-19 travel restrictions were still in place that summer, so Bourg worked remotely with Lemay and several other students to set up simulations exploring pollutants' behavior ranging from PFAS to anti-inflammatory drugs to insecticides.

"I actually ended up really liking this alternative project, and I think it’s even better suited for me than the original project would have been," said Lemay, who earned certificates in statistics and machine learning and sustainable energy.

The research was an excellent opportunity for Lemay to build her computer coding skills and learn molecular dynamics simulation software's intricacies. "When I first started with Professor Bourg, he had to walk me through step by step how to create a file" simulating a single chemical compound," Lemay said. Over time she learned more complexity variables like salinity and surface tension. Now the work is "like second nature."

In an internship with Ian Bourg (left), the summer after her first year at Princeton, Lemay learned how to set up simulations exploring pollutants' behavior. This work developed into her senior thesis with Bourg as her adviser. "She’s been thinking like a grad student since the very beginning," he says.

The summer project was a new direction in the lab’s research. Bourg quickly realized that he could rely on Lemay: "She’s been thinking like a grad student since the very beginning in terms of being super conscientious and questioning how we do things," said Bourg.

Lemay continued working as a research assistant alongside Ethan Sontarp for two years modeling over 80 organic pollutants at the water-air interface. They co-authored a 2023 paper reporting results published in Environmental Science & Technology; it has been downloaded more than 2,000 times making it Bourg's most-read paper last year—a testament its value researchers improving tracking remediation pollutants said Bourg.

In junior year conducted independent work Professor Barry Rand analyzing factors influencing rooftop solar energy adoption publishing analysis journal Energy Policy

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