The purification method removes PFA from water while converting waste into high value graphene

Researchers at Rice University have developed innovative solutions for environmental challenges. It is the removal and destruction of per capita and polyfluoroalkyl substances (PFAs), commonly referred to as “eternal chemicals.”

The research led by James Tour, Professor of Chemistry at TT and WF CHAO, Professor of Materials Science and Nanoengineering, and Graduate Student Felesia Scotland, will uncover how not only eliminate PFA from water systems, but also convert waste into high-value graphene, providing a cost-effective and sustainable approach to environmental detection. The study was published on March 31st in Nature Water.

PFA is a synthetic compound in a variety of consumer products and is associated with heat, water and oil resistance. However, the stability of those chemicals has sustained the environment, contaminating the water supply, and poses serious health risks, including cancer and destruction of the immune system. Traditional PFA disposal methods are expensive, energy-intensive, often generating secondary pollutants, spurring the need for innovative solutions that are more efficient and environmentally friendly.

“Our methods aren’t just destroying these dangerous chemicals, they turn waste into something valuable,” Tour said. “Upcycling spent carbon to graphene has helped create a process that is not only environmentally beneficial, but also economically viable, and offset the costs of repair.”

The research team’s process employs Flash Joule Heating (FJH) to tackle these challenges. By combining PFA with granular activated carbon (GAC) saturated with mineralizers such as sodium and calcium salts, the researchers applied high voltage to produce temperatures above 3,000 degrees Celsius in less than a second.

Strong heat disrupts the strong carbon fluorin bonds of PFA, converting them into inert and non-toxic fluoride salts. At the same time, the GAC is upcycled to graphene. Graphene is a valuable material used in industries ranging from electronics to construction.

The findings of this study produced one of the most common PFA contaminants, more than 96% dismantling efficiency and 99.98% removed Perfluorooctan acid (PFOA). Analytical tests confirmed that the response yielded undetectable amounts of harmful volatile organofluorides, a common by-product of other PFA treatments. This method also eliminates secondary waste related to traditional disposal methods such as incineration and the addition of spent carbon to landfills.

“This dual purpose approach is a game changer,” Scotland said. “We provide a scalable and cost-effective solution to urgent environmental issues while converting waste into resources.”

The implications of this study go beyond the two most studied PFAs, PFOA and Perfluorooctane sulfonic acid. This also works with the Teflon R, the most reversed PFAS type. The high temperature achieved during FJH suggests that this method can degrade a wide range of PFAS compounds and pave the way for a wider range of water treatment and waste management applications. The FJH process can also be tuned to produce other valuable carbon-based materials, including carbon nanotubes and nanodiamonds, further enhancing its versatility and economic appeal.

“With our promise of zero net cost, scalability and environmental benefits, our way represents a step forward in the fight against eternal chemicals,” Scotland said. “As concerns about PFA contamination continue to grow, this breakthrough provides hope for protecting water quality and public health around the world.”