Rice University researchers have unveiled a new method to eliminate harmful PFAS chemicals from water supplies and upcycle the waste into valuable graphene, providing an efficient, cost-effective solution to a global environmental challenge.
In a new study published in Nature Water, researchers at Rice University have unveiled a transformative approach to remove and destroy per- and polyfluoroalkyl substances (PFAS), commonly known as “forever chemicals,” which contaminate water supplies and pose serious health risks. The new method not only removes PFAS from water systems but also converts waste into high-value graphene.
PFAS are synthetic compounds prized for their durability and resistance to heat, water and oil. However, their stability renders them nearly non-degradable, leading to accumulation in the environment and significant health concerns, such as cancer and immune system disruptions.
Traditional methods for disposing of PFAS are often expensive, energy-intensive and produce secondary pollutants.
To tackle the problem, the Rice team — led by James Tour, the T.T. and W.F. Chao Professor of Chemistry and professor of materials science and nanoengineering, and graduate student Phelecia Scotland — developed a more sustainable and cost-efficient alternative using a technique called flash joule heating (FJH).
“Our method doesn’t just destroy these hazardous chemicals; it turns waste into something of value,” Tour said in a news release. “By upcycling the spent carbon into graphene, we’ve created a process that’s not only environmentally beneficial but also economically viable, helping to offset the costs of remediation.”
The FJH process involves mixing granular activated carbon (GAC) saturated with PFAS with mineralizing agents like sodium or calcium salts. A high voltage is then applied, generating temperatures exceeding 3,000 degrees Celsius in under a second. This extreme heat breaks the robust carbon-fluorine bonds in PFAS, turning them into harmless fluoride salts, while upcycling GAC into graphene — a material with extensive applications in electronics and construction.
The researchers reported a remarkable outcome: over 96% defluorination efficiency and a 99.98% removal rate for perfluorooctanoic acid (PFOA), one of the most common PFAS pollutants. Importantly, this method produces negligible amounts of harmful volatile organic fluorides, unlike other treatment methods, and entirely eliminates secondary waste from incineration or landfill disposal.
“This dual-purpose approach is a game changer,” added Scotland. “It transforms waste into a resource while providing a scalable, cost-effective solution to an urgent environmental issue.”
The potential applications of this innovative process extend beyond the commonly studied PFAS compounds, like PFOA and perfluorooctane sulfonic acid (PFOS). It is effective against even the most stubborn PFAS types, such as Teflon R. The high temperatures achieved suggest the method could degrade various PFAS compounds, setting the stage for broader applications in water treatment and waste management.
Moreover, the FJH technique can be adapted to produce other valuable carbon-based materials, including carbon nanotubes and nanodiamonds, broadening its economic and functional appeal.
“With its promise of zero net cost, scalability and environmental benefits, our method represents a step forward in the fight against forever chemicals,” Scotland added. “As concerns over PFAS contamination continue to grow, this breakthrough offers hope for safeguarding water quality and protecting public health worldwide.”
Source: Rice University