Removing per- and polyfluoralkyl substances (PFAS) from surface and groundwater has become an environmental and public health imperative, but methods for doing so are often complicated and costly, and may not destroy the molecules. Researchers at the University of British Columbia (UBC; Vancouver, B.C.; www.ubc.ca) have developed a hybrid iron-oxide and graphenic-carbon photocatalyst that can degrade PFAS efficiently in the presence of ultraviolet (UV) light.
The UBC system combines an activated carbon filter, which adsorbs the PFAS species, with its patented photocatalyst, which destroys the PFAS molecules. “We can put huge volumes of water through this catalyst, and it will adsorb the PFAS and destroy it in a quick two-step process,” says Johan Foster, UBC professor of chemical and biological engineering. “Many existing solutions can only adsorb [PFAS], while others are designed to destroy the chemicals. Our catalyst system can do both.”
The UBC work involves immobilizing a photoactive iron oxide on solid surfaces of mesoporous carbon. The researchers developed a “frugal” approach for preparing the photocatalyst that takes advantage of iron oxide, which is known for its photoactivity and ability to drive charge separation.
In tests, the UBC system demonstrated the ability to capture and destroy up to 90% of perfluorooctanoic acid, a common PFAS pollutant, in 3 hours under UV light. “The catalyst is not limited by ideal conditions,” explains Raphaell Moreira, a professor at the Universität Bremen who conducted the research while working at UBC. “Its effectiveness under varying UV light intensities ensures its applicability in diverse settings, including regions with limited sunlight exposure.” The catalyst also maintains high degradation rates over extended periods, demonstrating its stability and potential for long-term use, the researchers say.
The UBC team believes their catalyst could be a low-cost solution for municipal water systems, as well as specialized industrial projects, like cleaning up PFAS-containing waste streams. The researchers have set up a company, known as ReAct Materials, to explore commercial opportunities for the technology. Details of the work were published recently in the Nature journal Communications Engineering.