UK start-up Puraffinity has created a method of removing pollution from water using a material that selectively binds to PFAS chemicals.
Coated aluminium granules selectively target and extract harmful “forever chemicals” from water better than any other method.
Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals widely used in coatings and foams that resist oil, heat and water. There are thousands of types of PFAS, used in everything from dental floss to waterproof jackets and non-stick pans.
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| PFAS pollution in the Huron river in Michigan means anglers are warned not to eat fish they catch there Jim West/Alamy Stock Photo |
Several of these chemicals have been shown to cause harmful health effects, including thyroid issues, cancer and reproductive problems. They are also long-lasting environmental contaminants due to the tough carbon-fluorine bonds they contain.
Regulators in the US, UK and Europe are moving to restrict the use of PFAS chemicals in light of their public health risk. In March, the US Environmental Protection Agency (EPA) set legal drinking water limits for six of the most-studied PFAS compounds, limiting their concentration in water supplies to four parts per trillion.
Now, Puraffinity, a UK start-up spun out of Imperial College London, has developed aluminium granules coated with patented compounds with a high affinity for binding to PFAS chemicals.
The engineered coating can target and “lock up” PFAS chemicals from water. This selective adsorption is applied alongside the use of ion exchange, a more established method of PFAS removal in which negatively charged PFAS molecules bind to a positively charged resin.
The end product is fine, white granules that sit in a treatment chamber, which water is flushed through.
“We have both ion exchange and adsorption mechanism, so it’s a dual binding mechanism,” says Puraffinity co-founder Henrik Hagemann.
Third-party verification testing conducted by German research agency TZW and seen by New Scientist confirms that Puraffinity’s technology can remove PFAS to the standard required by the EPA, for a longer period of time than competitors. This means the technology lasts for longer before it has to be replaced or recharged, cutting energy demand and costs.
The PFAS can be discharged from the saturated granules by washing them through a “regeneration fluid”, before the concentrated PFAS chemicals are sent for destruction, says Hagemann. The granules can then be reused.
“We can now say… we have one material that can do both short-chain and long-chain [PFAS] to the 2023 EPA regulations,” says Hagemann.
Currently, Puraffinity can produce only 5 tonnes of its adsorbent material a year, but has funding to scale that up to 250 tonnes a year by the end of 2024, enabling commercial sales.
Hagemann says Puraffinity has been approached by airports, textile manufacturers and oil and gas companies all looking to reduce PFAS pollution from their sites.
Terrence Collins at Carnegie Mellon University in Pittsburgh, Pennsylvania, reviewed the third-party analysis and says Puraffinity’s technology looks “pretty impressive”. But he warns that more testing will be needed to ensure the solution is safe and non-toxic, and strict protocols will be necessary to ensure all captured PFAS substances are subsequently destroyed. Ultimately, the entire PFAS industry must be “shut down”, he stresses.
The European Union has set out plans to ban the use of all 10,000 PFAS chemicals during the 2030s, a move Hagemann supports. But he says exemptions for the semiconductor, solar and vaccine industries mean PFAS use will probably continue through the 2030s and beyond.
“We think that there’s going to be a replacement of PFAS for most uses,” says Hagemann. “You don’t need it in your roof tiles. You don’t need it in your spray for your bicycles. Frankly, those uses are promiscuous. But there are essential uses where you’re likely to continue using it, especially related to the net-zero journey.”
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