Researchers at Ritsumeikan University in Japan as well as Colorado State University have developed a groundbreaking method that achieves complete breakdown of perfluoroalkyl substances (PFAS), commonly known as “forever chemicals,” using visible LED light at room temperature. This innovation represents an important advance in environmental remediation and sustainable fluorine recycling, addressing one of the most persistent challenges in chemical pollution.
PFAS are synthetic chemicals prized for their exceptional stability, resistance to heat, and water-repellent properties. Since their introduction in products like Teflon in 1938, PFAS have become ubiquitous in consumer goods, industrial applications, and firefighting foams. However, their resilience means they do not degrade naturally, leading to accumulation in water, soil, and living organisms—including humans—where they are linked to carcinogenic and hormonal effects. PFAS contamination is now a global concern, with traces found even in remote regions like Antarctica. Traditional disposal methods require temperatures above 400°C, making PFAS destruction energy-intensive and costly. As a result, PFAS-containing waste often ends up in landfills, posing long-term environmental risks.
The LED Light-Based Solution
The new method leverages photocatalysis, a process in which light energy drives chemical reactions. The researchers used cadmium sulfide (CdS) nanocrystals and copper-doped CdS (Cu-CdS) nanocrystals, both coated with mercaptopropionic acid (MPA) ligands, suspended in a solution with PFAS and triethanolamine (TEOA). When exposed to 405-nanometer visible LED light, the nanocrystals absorb photons, generating electron-hole pairs. The MPA ligands detach, allowing PFAS molecules to adsorb onto the nanocrystal surface.
To enhance the reaction, TEOA is added to capture the holes, preventing recombination and extending the lifetime of the reactive electrons. These electrons undergo Auger recombination, creating highly energetic electrons capable of breaking the notoriously strong carbon-fluorine (C-F) bonds in PFAS. Laser flash photolysis confirmed the presence of hydrated electrons, which are crucial for the defluorination process.
Results
The method achieved remarkable results:
- 100% breakdown of perfluorooctanesulfonate (PFOS), a common PFAS, in just eight hours.
- 81% breakdown of Nafion, a widely used fluoropolymer, in 24 hours.
Defluorination efficiency was found to depend on the concentrations of nanocrystals and TEOA, as well as the duration of light exposure. For PFOS, defluorination rates increased from 55% after one hour to 100% after eight hours.
Implications for Fluorine Recycling
Fluorine is a vital element in pharmaceuticals, clean energy, and advanced materials. By recovering fluorine from decomposed PFAS, this technique could reduce the need for new fluorine production and support a circular economy. The method has potential to enable sustainable fluorine recycling and mitigate the environmental impact of PFAS.
This LED light-driven technique offers a promising, energy-efficient, and scalable solution for breaking down PFAS and recovering valuable fluorine. It addresses both the environmental persistence of “forever chemicals” and the need for sustainable resource management, paving the way for future advances in pollution control and recycling technologies.
More information is available here
Image: A researcher working in the Miyake Lab at Colorado State University. Credit: Colorado State University College of Natural Sciences/John Cline
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