A newly developed gel can pull the forever chemicals, per- and polyfluoroalkyl substances (PFAS), out of water. Now, researchers want to understand the principle behind it – so that stopping PFAS from leaking into nature and, eventually, into people can become an easy and affordable solution for industry.
They are in your frying pan, in the rain – and in your body. PFAS are chemicals that do not break down easily and accumulate in nature, animals and humans. That is why they are called forever chemicals – and they pose a growing threat to our health.
PFAS have been used in many things, including non-stick pans and firefighting foam. The toxic effects became clear years later – and the fact that these chemicals are nearly impossible to remove from the environment.
Large quantities of PFAS still leak into nature – into lakes, groundwater and even drinking-water – posing risks to both ecosystems and human health. But now, researchers have developed a gel that can remove up to 96% of these harmful chemicals from water before it leaves the building.
The gel could become a key tool for stopping PFAS pollution before it reaches our taps, our rivers – or our bodies.
The research has been published in Advanced Materials Interfaces.
“You can place the gel inside pipes and tanks at factories, where it captures PFAS before the wastewater leaves the site. This could lead to cleaner water and less chemical pollution overall,” explains Giuseppe Di Palma from the National Centre for Nanofabrication and Characterization at the Technical University of Denmark in Kongens Lyngby.
A low-cost gel tackles a global pollution threat
Numerous efforts are underway worldwide to combat PFAS pollution. In this study, researchers developed a novel gel capable of removing PFAS directly from water – such as industrial wastewater.
The gel is based on a material called UiO-66, which contains tiny crystalline particles with pores that bind PFAS. UiO-66 becomes easier to handle and far more suited for water purification in gel form than in its usual powder form.
Powder is tricky to use in pipes and tanks because water does not flow through it easily, it can clump, settle, or block water flow, making it less practical. Gel, on the other hand, allows water to pass through – giving PFAS time to stick to the material. This is why the researchers developed a gel version of UiO-66.
The gel retains its three-dimensional, porous structure even after use and is not broken down by contact with the PFAS. That makes it suitable for repeated use inside things such as wastewater pipes.
As the water flows through, PFAS molecules chemically bind to the gel’s inner surfaces – they stick to specific areas of the gel – while the pure water passes through.
“The idea is to let the wastewater flow through the gel, which traps PFAS as the water moves through the structure. It is used in industrial products and often found in polluted groundwater. But the gel’s structure can be adjusted to target other types of PFAS as well,” says co-author Joerg R. Jinschek, Professor and Group Leader.
Removes nearly all “forever chemicals” in minutes
To test the gel’s potential, researchers evaluated how effectively UiO-66 can remove PFOA (perfluorooctanoic acid), a very persistent and harmful chemical in the PFAS group that has widely been used in products like non-stick cookware and firefighting foam due to its resistance to water, oil, and heat.
The experiments showed that the gel removed up to 96% of PFOA. The results were measured using a sensitive technique called Fluorine-19-NMR spectroscopy, which accurately detects how much fluorine compound (i.e. PFOA) remains in the water after filtration.
Giuseppe Di Palma, the lead author of the study, says the technology has the potential to reduce PFAS levels below the limits set by health authorities for safe drinking-water.
In the experiments, just a few grams of gel were enough to remove nearly all PFAS from the water. The gel can be produced for less than 20 EUR per kilogram and can absorb about 30 mg of PFAS per gram of gel – a strong starting-point that the researchers are now working to improve. They are tweaking the material’s structure and pore size to boost its capacity.
“This shows that the gel is both effective and affordable – and could become an important tool in tackling PFAS pollution in wastewater,” adds Giuseppe Di Palma. The researchers now are also investigating the gel’s selectivity towards other PFAS types.
From laboratory bench to water pipes
Encouraged by the results, the researchers now hope to commercialise their invention. They have tested the gel as a membrane by applying it to filter paper. In three successive rounds, it removed more than 95% of PFOA – using nothing but gravity, without added pressure.
That makes the method simple and scalable – able to trap PFAS before wastewater is released into the environment. The idea is to deploy the gel directly in water pipes carrying industrial wastewater away from factories, for example.
“Before it hits the market, the team wants to know how many rounds the gel can go – how long it can trap different types of PFAS before losing its punch.”
“We also want to more deeply understand why the gel works so well. PFOA clearly binds chemically to the zirconium in the gel, but we are now investigating exactly how that bonding happens – down to the single-molecule level – so we can fine-tune the material and make it even more efficient. That is the puzzle we are trying to solve now,” concludes Joerg R. Jinschek.
