PFAS are a range of chemicals with a bad reputation. Evidence is growing that they cause cancer and are harmful to unborn children. Yet more and more of these types of per- and poly-fluoroalkyl substances (PFAS) are dumped into the environment because they are used in everyday goods, such as non-stick pans, fire extinguisher foams, food packaging, and waterproof clothing.
One of the leading research universities in Belgium and Europe, KU Leuven, has now figured out a new way to filter these out of the water using a kind of mineral sponge made of zeolite. The university has just published this on its website.
Dutch construction sector
There is still a lot that is unknown about how serious the problems with PFAS actually are. The European Union’s policy is to slowly but surely reduce PFAS down to zero unless they are absolutely necessary.
There are about 6000 different types of PFAS, some of which are not toxic at all. The big breakthrough came in 1938 when the American company DuPont more or less accidentally came up with the chemical compound polytetrafluoroethylene (PTFE), a type of PFAS that would later form the basis of Teflon, well-known for e.g. pans and rainwear. PFAS has been notorious in the Netherlands for being the reason why numerous construction projects have been suspended over the past few years.
Nevertheless, the substances remain popular in industry because of their advantageous characteristics: they are resistant to high temperatures, caustic products, and electricity, and they are water- and dirt-repellent.
Non-biogradable
The downside is that they are not biodegradable or are difficult to break down. That’s why they are also called forever chemicals that spread through the air and water and end up in our food and drinking water.
“Production of some types of PFAS has been more strictly regulated in recent years, but has not yet been completely curtailed,” explains researcher Matthias Van den Bergh. “Because of the strict regulations, the industry is looking for other molecules which have similar properties, although this is obviously not a solution for the pollution that has been piling up in nature over the past decades.”
That is why Van den Bergh, together with professor Dirk De Vos, went looking for a way to filter PFAS out of water. The main challenge was that PFAS molecules only occur in very low concentrations in water. De Vos: “Even with high levels of pollution, we’re talking about no more than one microgram per liter. So, it’s like looking for a needle in a haystack.”
Cat litter
Van den Bergh: “Nevertheless, we have succeeded in developing an efficient filter material. We use a zeolite, a porous substance with tiny cavities. This material in powder form attracts PFAS molecules and traps them in its pores. The great thing about this technology is that it works very selectively. Harmful PFAS substances are filtered, but the other innocuous components in the water are not.”
Zeolites are minerals that exist in both natural and artificial forms. Natural zeolites are used as absorbent material in cat litter, amongst other things. Artificial zeolites are used in detergents and other products.
The researchers have patented the zeolite concept. Yet according to De Vos, there is still a long way to go before a functional application can be created. “We believe in the potential of this material. Nevertheless, the challenge is to produce it on a large scale at a reasonable price. We will also continue to research in what way and in what form the filters can best be used.”
Check out our dossier on environmental pollution as well.
