Chemists have created a sustainable method to remove “forever chemicals,” or PFAS, from water using a unique approach involving metal-containing polymers like ferrocene. These fluorine-rich organic compounds have diverse applications, such as making raindrops slide off outdoor jackets, serving as non-stick layers in food packaging, and being essential in fire-extinguishing materials. Introduced in the 1940s, PFAS’s range of use has grown, but this has led to concerns due to the stable nature of these chemicals.
Because PFAS lack natural degradation pathways, they accumulate persistently in the environment, leading to potential health risks and environmental problems. Traces of PFAS can be found globally in water, air, soil, plants, and animals, and they eventually make their way into human bodies. The full health risks of these chemicals remain uncertain, although some studies have suggested reproductive health impacts. What is known is that these synthetic compounds do not belong in the natural world, making the reduction of PFAS contamination crucial.
Traditional PFAS remediation is complicated, with the processes themselves possibly having negative effects on the environment and climate. Detection is also difficult, as small quantities of PFAS can create significant effects. Until now, PFAS have been typically removed from water by filtration through special membranes or activated carbon adsorbents, and their permanent destruction required harsh chemicals or incineration.
A research team led by Markus Gallei from Saarland University and Xiao Su from the University of Illinois, along with doctoral students Frank Hartmann and Paola Baldaguez, have discovered a novel electrochemical method. This approach can extract PFAS chemicals from water and then release them efficiently for destruction, without needing to incinerate the filter.
The researchers’ method relies on metal-containing polymers known as metallocenes, particularly ferrocene or cobaltocene. By applying voltage, these metallocenes can switch their electrical state, capturing and releasing PFAS molecules. Cobalt is found to be more effective than iron in this process. This technique allows PFAS to be removed and then released, regenerating the electrode for repeated use.
Unlike activated carbon filters that must be destroyed once saturated, the metallocenes can be switched a thousand times, as highlighted by Markus Gallei. The research team is now focusing on upscaling the development to enable the removal of these stubborn contaminants from rivers and oceans. The innovative work was published in ACS Applied Materials & Interfaces on April 28, 2023.
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Frequently Asked Questions (FAQs) about PFAS removal
What are PFAS, and why are they called “forever chemicals”?
PFAS (Per- and Polyfluoroalkyl Substances) are fluorine-rich organic compounds known for their diverse applications and stable nature. They are called “forever chemicals” due to their persistence in the environment, lacking natural degradation pathways, leading to accumulation in water, air, soil, plants, animals, and humans.
How have PFAS been traditionally removed from water?
Traditionally, PFAS have been removed from water using special membranes or lower-cost activated carbon adsorbents. Recovering and permanently destroying PFAS from these systems has required harsh chemical conditions or incineration.
What is the new method developed to remove PFAS from water?
A research team has developed a new electrochemical method using metal-containing polymers known as metallocenes, specifically ferrocene or cobaltocene. By applying voltage, these metallocenes can switch their electrical state and capture and release PFAS molecules, allowing them to be efficiently removed from water and destroyed without incineration.
How does the new method differ from traditional methods?
Unlike traditional methods that use filtration and may require incineration, the new method uses electrochemical processes with metallocenes that can be switched thousands of times, enabling the sustainable removal and destruction of PFAS. This method is also aimed at reducing the detrimental impact on the environment and climate.
What are some of the common uses of PFAS?
PFAS are used in a wide variety of applications, including making raindrops glide off outdoor jackets, serving as non-stick layers in food packaging, and being essential components in fire-extinguishing foams and safety equipment used by firefighters.
What are the potential health risks associated with PFAS?
The full health risks of PFAS are still not clear, but initial laboratory animal studies have shown that these chemicals may impair reproductive health. Their synthetic nature also means they do not belong in the natural environment or living organisms, which has raised concerns about their presence in humans and the ecosystem.
More about PFAS removal
- Saarland University
- University of Illinois Urbana-Champaign
- ACS Applied Materials & Interfaces
- Information on PFAS
