Scientists have, for the first time, watched “forever chemicals” break apart step by step on an electrically charged metal surface, pointing to new ways to remove them from drinking water. Using U.S. National Science Foundation (NSF) ACCESS allocations on the Expanse supercomputer at the University of California San Diego School of Computing, Information and Data Sciences’ San Diego Supercomputer Center (SDSC), the team focused on better understanding per- and polyfluoroalkyl substances (PFAS), a large family of man-made chemicals used in products like nonstick pans and firefighting foams that linger for decades in the environment and are linked to health concerns.

In a new study in Environmental Science & Technology Letters, a team from the University of California, Riverside, led by postdoctoral associate Kamal Sharkas and professor Bryan Wong, ran detailed computer experiments of a common PFAS compound on a copper surface under an applied voltage. Instead of just taking static snapshots, they followed how the molecule’s atoms moved over time and how key bonds in the chemical backbone began to stretch and finally snap. Those bonds, between carbon and fluorine atoms, are what make PFAS so tough to destroy in the first place. 

​The significance of this study lies in showing, at the atomic level, exactly how and when PFAS bonds can be broken using electrochemical means; that is, by applying an electric charge to a metal surface submerged in water. The new findings translate fundamental chemistry into actionable engineering guidance, which is a crucial step toward affordable, effective PFAS remediation in the drinking water supplies that communities depend on.

This new way of using supercomputers provided by NSF ACCESS could be a powerful design tool for future PFAS cleanup technologies. By swapping in different electrode materials in the model and adjusting the voltage, we can quickly test which combinations are most likely to pull apart PFAS efficiently and with less energy, before building costly hardware.

-Bryan Wong, UC Riverside

“Our simulations showed that when the metal surface was made electrically negative enough, extra electrons rushed into the PFAS molecule, weakening specific carbon–fluorine bonds until they broke and released fluorine into the surrounding liquid, matching what lab experiments had hinted at before,” said Wong, a chemistry professor at UC Riverside. “At milder voltages, however, those ultra-strong bonds stayed mostly intact, helping explain why many treatment approaches struggle to fully eliminate PFAS.”

Running these kinds of “real-time” virtual experiments is enormously demanding, which is why the researchers turned to NSF allocations on SDSC’s Expanse. They used thousands of computing cores to follow the motion of atoms over more than a trillionth of a second, which is long enough in the microscopic world to see several of the toughest bonds in the PFAS chain stretch by more than half their normal length and then break. When the team tried a simpler approach using smaller calculations that didn’t realistically allow electrical charge to flow, they didn’t observe any bond breaking at all, underscoring the need for full-scale electrochemical simulations.

Resource Provider Institution(s): San Diego Supercomputer Center (SDSC)
Resources Used: Expanse
Affiliations: UC Riverside
Funding Agency: NSF 
Grant or Allocation Number(s): CHE240173

The science story featured here was enabled by the U.S. National Science Foundation’s ACCESS program, which is supported by National Science Foundation grants #2138259, #2138286, #2138307, #2137603, and #2138296.