Scientists discover new technique that can destroy dangerous ‘forever chemicals’

The toxic chemicals are thought to be contaminating the drinking water of over 200 million Americans.
Baba Tamim
Filling glass of water from the tap.
Filling glass of water from the tap.

fcafotodigital/iStock 

In a major breakthrough, researchers have discovered a novel method to break down the dangerous "forever chemicals."

A new method for decomposing some PFAS (forever chemicals) compounds could represent a major breakthrough in addressing widespread environmental contamination around the world, according to a news report published by The Guardian on Thursday.

PFAS, or per and polyfluoroalkyl substances, are dubbed "forever chemicals" because they do not degrade naturally, and man-made processes to destroy them are costly, energy-intensive, and yield questionable results.

"The fundamental knowledge of how PFAS degrades is the single most important thing coming out of this study," said Will Dichtel, a Northwestern University researcher and co-author of the new study.

About 12,000 compounds comprise the PFAS class, and the method developed by researchers from the Northwestern University of California at Los Angeles and Tianjin University is effective on one subclass, perfluoro carboxylic acids.

Every PFAS compound has one thing in common that has made them virtually indestructible thus far: they all have at least one fluorinated carbon atom.

The new method "defluorinates" the compounds with a solution of water and the dipolar aprotic solvent dimethyl sulfoxide (DMSO), resulting in carbon and inorganic fluoride, both of which are relatively harmless.

The non-degradable PFAS

The non-degradable PFAS continues to circulate and accumulate in the environment, and the toxic chemicals are now thought to be contaminating the drinking water of over 200 million Americans.

They've been found in the Arctic, in rain all over the world, and are thought to be in 98% of Americans' blood. New research has discovered them in alarmingly high concentrations in some foods and the air.

Earlier, Interesting Engineering documented how rainwater is not safe to drink anymore due to 'forever chemicals.'

Despite the fact that technology to remove PFAS from the environment existed, researchers weren't able to figure out how to completely decompose the chemicals after removal until now.

The effectiveness of a new low-temperature technique for breaking down PFAS was described in a study published in the Science journal on Thursday.

Public health advocates have long been concerned about the widespread disposal of chemicals through practices such as deep injection well and landfilling. Evidence suggests that the frequently incinerated chemicals only break down the compounds, releasing potentially hazardous PFAS fragments into the air.

"There is no way to dispose of PFAS that is benign, so there is a need for a method to get rid of PFAS in a way that does not still pollute," said Brittany Trang, a Northwestern researcher and one of the study's lead authors.

Numerous industries and thousands of consumer goods use PFAS to make them resistant to heat, water, and stains. However, the compounds have been linked to severe diseases like cancer, congenital disabilities, liver disease, kidney problems, lowered immunity, and high cholesterol.

'Meaningful' findings

According to the researchers, their method could be expanded to address PFAS in other subclasses, requiring less energy than other methods used to try to destroy PFAS.

"This method operates under mild conditions and makes benign products, and that makes it immediately promising for further study," said William Dichtel, a chemistry professor at Northwestern University.

Researchers stressed that the findings are preliminary and that the method is far from being ready to be scaled up and applied commercially. Reverse osmosis, granular activated carbon, or other forms of filtration would need to be used to first filter the chemicals out of the contaminated water because they are present in it in toxic amounts at very low concentrations.

The new method could be used to treat chemicals that have been concentrated in wastewater.

"We have never had a satisfactory answer to 'What we are going to do with these and how can we clean our water'?" Dichtel said.

Dichtel, who has been working on developing PFAS decomposition methods for about seven years, called the findings "meaningful."

Abstract:

Per- and polyfluoroalkyl substances (PFAS) are persistent, bioaccumulative pollutants found in water resources at concentrations harmful to human health. Whereas current PFAS destruction strategies use nonselective destruction mechanisms, we found that perfluoroalkyl carboxylic acids (PFCAs) could be mineralized through a sodium hydroxide–mediated defluorination pathway. PFCA decarboxylation in polar aprotic solvents produced reactive perfluoroalkyl ion intermediates that degraded to fluoride ions (78 to ~100%) within 24 hours. The carbon-containing intermediates and products were inconsistent with oft-proposed one-carbon-chain shortening mechanisms, and we instead computationally identified pathways consistent with many experiments. Degradation was also observed for branched perfluoroalkyl ether carboxylic acids and might be extended to degrade other PFAS classes as methods to activate their polar headgroups are identified.

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