Researchers at Bernal Institute and University of Limerick have developed a new material that can eliminate so-called ‘forever chemicals’ from water.
The research team are working with colleagues from the Technical University of Munich (TUM) in Germany, have discovered a solution to filter harmful chemicals from drinking water.
Per- and Polyfluoroalkyl Substances (PFAS) are a group of man-made chemicals that have been in use since the 1940s. Due to their ability to resist heat, oil, stains, grease, and water, PFAS have been widely used across a range of industrial and consumer applications, from non-stick cookware and water-repellent fabrics to firefighting foams and industrial processes.
However, their chemical stability — key to their effectiveness in these uses — also means they persist in the environment and the human body. Known as ‘forever chemicals’, the substances can accumulate in the body via food and drinking water and cause serious illnesses.
Prolonged exposure can cause liver damage, tumours and hormonal disorders and they are considered a severe threat to human health.
The researchers at Bernal, UL and TUM have now developed a new, efficient method of filtering these substances out of drinking water. They rely on so-called metal-organic framework compounds, which work much better than the materials commonly used to date. Even extremely low concentrations of PFAS in the water can still be captured.
Dr Soumya Mukherjee, member of the Bernal Institute and an Assistant Professor of Materials Chemistry at UL’s Department of Chemical Sciences, working with researchers in TUM, developed the porous, sponge-like metal-organic frameworks (MOFs) that can filter these PFAS chemicals out of drinking water.
The new discovery has just been published in the journal Advanced Materials.
“The filters delivered removal performance even when they were present in extremely low concentrations of a few parts per billion, that is, only a handful of PFAS molecules among billions of water molecules,” explained Dr Mukherjee.
“With fast and record-high removal properties realised for at least two of the legacy PFAS chemicals, this new class of PFAS filters introduces an as-yet-unknown design principle for future adsorbent design.
“In fact, this marks the first instance of trace PFAS removal from freshwater containing two parts per billion of PFAS using porous adsorbent materials that demonstrate both rapid removal kinetics and excellent recyclability.”
The research team identified identified water-stable metal-organic framework compounds made of zirconium carboxylate as particularly effective PFAS filters.
The bespoke class of materials is characterised by the adaptable pore sizes and surface chemistry. The materials are water-resistant and highly electrostatically charged. By specifically designing the structures and combining them with polymers, the filter capacity has been significantly improved compared to materials already in use, such as activated carbon and special resins.
Dr Mukherjee highlighted the profound societal impact of removing PFAS from water.
“During the Second World War, fluorocarbons became the silent enablers of the 20th Century’s greatest technological achievements – the bomb and also Teflon, the stuff of convenience cookware, spaceflight and implantable medical devices.
“Today, these fluorocarbons, PFAS, persist as legacy chemicals prevalent in water systems serving hundreds of millions of people around the world. So extreme is their persistence that science is yet to determine an environmental half-life – the point at which the environmental load would otherwise become half.
“From soil to sea, the PFAS cycle spins a web of contamination across ecosystems far and wide. To mitigate the disquieting effects of PFAS, we have just innovated a new approach to adsorbent design.
“Our team approach was key to this success. The chemistry among our team was just as important as the chemistry of the porous materials.”
According to the researchers, the large-scale translation of the newly identified filter material class in water treatment facilities now requires iterative process design across higher technological readiness levels.
“Scaling this innovation from the laboratory to pilot-scale operations arguably presents additional challenges in process engineering,” said Dr Mukherjee.
“However, it will be some time before this new filter material is adopted on a large scale in waterworks. The newly discovered principle would have to be implemented with sustainably available, inexpensive materials that are safe in every respect. This will require considerable further research and engineering solutions.”
