Scientists have discovered a new way to break apart ‘forever chemicals’, the notoriously stubborn pollutants that contaminate our waterways and threaten public health. It contributes to a growing list of potential methods of dealing with long-lived compounds.
News of a simple, low-energy way to degrade some, but not all, forever chemicals came in August from researchers at Northwestern University. They described how these tightly bonded, long-chain synthetic chemicals ‘fell apart’ under unexpectedly mild conditions. They were once thought impossible to degrade without a great deal of energy.
A team of scientists at the University of California (UC) Riverside have reported an alternative method for supercharging the destruction of PFAS chemicals in the water.
It uses UV light and hydrogen gas to break down these harmful substances found in drinking supplies.
Long-lasting PFAS (per- and polyfluoroalkyl substances) have been used as non-stick and waterproofing agents for decades. They’ve found their way into everything from fire-fighting foam to cosmetics. They were later nicknamed ‘forever chemicals’ for the way they persist in the environment. PFAS have been found in concerningly high drinking water levels worldwide. They’ve been linked to health problems, such as liver cancer.
If this research progress continues, they might finally be unstuck.
“The advantage of this technology is that it is very sustainable,” said Haizhou Liu, a chemical and environmental engineer at UC Riverside and senior researcher on the team who developed the new patent-pending process, which doesn’t generate any undesirable byproducts.
Putting aside regulatory levers that limit the risks of environmental contamination, there are two parts to solving the PFAS problem. The first involves removing the material from environmental resources by filtering drinking water supplies (often using carbon). It is an easier task than cleaning up contaminated soils or groundwater.
The next and more difficult step is disposing of the concentrated PFAS chemicals or destroying them without creating harmful substances. PFAS can be burned off at high temperatures, but this is expensive. Incinerating products containing PFAS risks spreading them further.
Where this stands in the battle against forever chemicals
It’s not the first time researchers have tried zapping PFAS chemicals to break them. Another team at Clarkson University in New York has been working with the US Air Force to treat PFAS-contaminated water, using plasma reactors and argon gas to split PFAS molecules.
Plasma gas is ionised gas made of free-roaming electrons and positive ions. In pilot tests of contaminated water purged from monitoring wells on air force sites, treatment in plasma reactors for up to 50 minutes degraded between 36 and 99 per cent of PFAS chemicals, some faster than others.
With a problem this large, we need to consider all options. “The general consensus is that there’s not a one-size-fits-all solution” to degrading forever chemicals, chemical engineer Selma Mededovic Thagard of Clarkson University told the American Geophysical Union’s Eos magazine.
Liu and his UC Riverside colleagues think they can make their process more energy-efficient. They want to test other low-energy light sources and tinker with their setup. The hope is to enhance the diffusion of hydrogen gas through the water.
This will be important if the technology can scale up from lab experiments with test tubes to real-world industrial applications, as it has been the major hurdle for other methods.
“We are optimising it by trying to make this technology versatile for a wide range of PFAS-contaminated source waters,” Liu says. “The technology has shown very promising results in destroying PFAS in drinking water and different industrial wastewater.”
The research was published in the Journal of Hazardous Materials Letters.
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