Per- and poly-fluoroalkyl substances (PFAS) are extremely stable chemical compounds. This stability gives them very useful properties for multiple industrial uses, including in firefighting foams, nonstick cookware, food packaging, insecticides, and waterproof and fire-resistant fabric. But this same property also means that they don’t break down easily and therefore accumulate in the environment. They are now so widespread that almost every person on Earth has been exposed to PFAS and has them in their blood.
Researchers at the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) have used electricity to generate substances – including free radicals – that are extremely strong oxidising agents. These substances strip the PFAS molecules of electrons and thus break them down into smaller – and safe – components.
Furthermore, this approach – named pfasCARE™ – is not limited to PFAS and can potentially be used to treat almost all organic contaminants. The oxidising agents themselves are unstable and rapidly break down into harmless compounds.
“Previous iterations of this technology, which is subject to a patent application, have required expensive materials, such as diamonds, to be effective”, explained lead researcher Dr Cheng Fang, Senior Research Fellow at the University of Newcastle’s Global Centre for Environmental Remediation, CRC CARE’s partner on the project. “With pfasCARE, we have been able use lead peroxide – a common, inexpensive industrial material to dramatically cut the cost of production.”
Australian authorities are recognising a growing number of sites where PFAS have contaminated groundwater, surface water and soil, in some cases spreading to residential areas. Current remediation approaches involve either removal or breakdown.
“While removal can be effective,” said Dr Fang, “it does not solve the problem of what to do with the hazardous chemicals, which require subsequent treatment to ensure they are not gradually released again.”
Breakdown or mineralisation ensures that PFAS are broken down to safer substances such as carbon dioxide and fluoride. However, the innate stability of PFAS means that an enormous amount of energy (e.g. temperatures greater than 1100 °C) is required, and this is very costly. Cheaper breakdown approaches, using chemicals, ozone or ultraviolet light to oxidise PFAS, have been largely unsuccessful or have left behind by-products that are as hazardous as the PFAS themselves.
“CRC CARE plans to offer pfasCARE in combination with its proprietary matCARE™ technology, a modified clay substance that irreversibly locks up PFAS,” said CRC CARE Managing Director Professor Ravi Naidu. “At this stage, pfasCARE can be used to treat contaminated wastewater or groundwater, with research under way to target contaminated soil as well. This is a world-first approach that will offer a complete clean-up solution for PFAS-contaminated sites, something that until now has not been available.”
PFASs have been used in the past to improve the ability of fire-fighting foam to smother fire. In such ‘aqueous film-forming foams’, or AFFFs, these chemicals have been used on fires at many thousands of emergency and training sites worldwide over the past half-century.
A growing body of research has shown that PFAS can be dangerous to human health. PFOS (perfluorooctanesulfonate) and PFOA (perfluorooctanoic acid) in particular are two commonly used PFAS that are known to enter ecosystems and move up food chains, accumulating in animal and human tissue, including the liver and blood. PFAS have been linked to bladder and liver cancer, endocrine disruption, and developmental and reproductive toxicity, including neonatal mortality, and are potentially lethal to animals.
CRC CARE is an Australian and world leader in research, technology development and policy guidance for assessing, cleaning up and preventing contamination of soil, water and air. The centre was launched in 2005 as part of the Australian Government’s Cooperative Research Centres Programme, which supports industry-led collaborations between industry, researchers and the community.