The role of per- and polyfluoroalkyl substances (PFAS) in the energy transition
Is it possible to transform eternal pollutants into a resource for the energy transition? Apparently yes, and new research led by Rice University in Texas has shown this. Scientists have successfully used PFAS in lithium extraction from high-salinity brine, doing so with less water and energy than traditional methods.
What are per- and polyfluoroalkyl substances (PFAS)?
PFAS – an acronym for per- and polyfluoroalkyl substances – are a group of over 10,000 synthetic compounds, still used globally today in the synthesis of pharmaceuticals, pesticides, packaging, firefighting foams, paints, and a long list of other products.
They were specifically created to offer high stability and resistance to extreme conditions, but these very characteristics have made them an extremely dangerous environmental pollutant, capable of resisting natural degradation processes and bioaccumulating. In other words, they have all the requirements to represent a gigantic problem for both ecosystems and human health. Classified as carcinogenic to humans, PFAS can suppress immune system activity, impair endocrine and metabolic function, and promote infertility, osteoporosis, and diabetes.
A decidedly grim picture that is being addressed – albeit with some slowness – particularly at the level of water treatment plants and activated carbon filters.
Lithium extraction from brine with spent activated carbon
The Rice University study fits into this context by offering a means to valorize PFAS waste and transform it from a problem into a resource. Specifically, the group focused on field-collected firefighting foam samples treated with granular activated carbon (GAC).
GAC offers an effective method for removing eternal pollutants but in turn generates an additional waste stream. The team used PFAS-contaminated GAC as a fluorinating agent, adding it to high-salinity brine and rapidly heating it to over 1,000 degrees Celsius (before cooling it just as quickly).
The heat breaks the carbon-fluorine bonds typical of PFAS. The carbon becomes graphene, while the fluorine binds to metals present in the brine, causing them to precipitate as metal fluorides:
- LiF (lithium fluoride),
- NaF (sodium fluoride)
- KF (potassium fluoride)
- MgF2 and CaF2 (magnesium and calcium fluorides)
Lithium fluoride has very low water solubility compared to other lithium salts, and the developed process utilizes washing and distillation steps to isolate it from the other fluorides formed.
Advantages of lithium fluoride recovery
The researchers then collected the volatile stream containing lithium fluoride, recovering 82% of the available lithium fluoride with 99% purity. The next phase of the study was to test the practical efficacy of the new method for lithium extraction from brine. How? By incorporating the lithium fluoride into battery electrolytes and testing it for stability and impact on cell performance.
“Electrolytes containing the recovered lithium fluoride showed greater stability and superior performance, confirming that the process produced a quality lithium source suitable for use in batteries,” writes Stephanie Baum on the Texas university’s website.
“By considering waste as potentially useful compounds, we were able to convert problematic PFAS adsorbed on activated carbon into a valuable metal usable, for example, in batteries,” stated James Tour, the T.T. and W.F. Chao Professor of Chemistry and corresponding author of the study. “This promises significant environmental, economic, and efficiency benefits.”
The research Waste per- and polyfluoroalkyl substance-assisted flash fluorination for lithium recovery from brine was published in Nature Water (2026).