Researchers develop scalable, reusable filter that removes 75% of forever chemicals from water.

A team from the University of Bath in the United Kingdom has developed 3D-printed indium oxide lattice filters that remove up to 75% of one of the most common persistent chemical contaminants on the planet from water – PFAS.

Per- and polyfluoroalkyl substances (PFAS) are a group of manmade chemicals developed in the 1940s to make products that resist water, oil and grease, heat and stains. They can include household cleaners, personal care products, water-resistant fabrics and textiles, nonstick cookware and food packaging.

PFAS have earned the notorious nickname 'forever chemicals' because of their impervious nature. The strong carbon-fluorine bonds that make these substances useful for keeping products clean are also what make them nearly impossible to break down.

As a result, PFAS persist in our environment, spreading through waste streams, contaminating resources, and accumulating in our bodies. Long-term exposure to certain PFAS has been linked to serious health issues, including cancer, birth defects, liver damage, immune system disruption, high cholesterol, thyroid disease, asthma, and allergies.

"PFAS, or 'forever chemicals,' are a major focus in water treatment and public health. We have created an efficient way to remove these chemicals from water without using lots of energy," said study co-author Liana Zoumpouli, a research associate in Bath's Department of Chemical Engineering.

An elegant solution

University of Bath

These 3D-printed indium oxide lattice filters remove up to 75% PFAS from water.

Based on positive results in various scientific studies, the U.K. researchers decided to investigate the potential of indium oxide in water treatment. They settled on a self-supported structure to allow for easy transport and removal.

The team then used extrusion-based 3D printed lattices to maximize the surface area and create permeable blocks that water can pass around and through. The four-centimeter (one and a half inches) block prototype structures were printed using a special ceramic indium oxide fluid.

"Using 3D printing to create the monoliths is relatively simple, and it also means the process should be scalable. 3D printing allows us to create objects with a high surface area, which is key to the process," Zoumpouli said. "Once the monoliths are ready you simply drop them into the water and let them do their work. It's very exciting and something we are keen to develop further and see in use."

They tested the infused ceramic's adsorption capabilities using perfluorooctanoic acid (PFOA), one of the most prevalent PFAS chemicals. This contaminant bonded successfully with the indium oxide and was removed.

In the space of three hours, the structures filtered out 53% of the PFOA in the experiment using a recirculating flow system for the water.

The structures also got more efficient after undergoing high-temperature thermal 'regeneration' treatment following each use. By heating the monoliths at 500 degrees Celsius (932 degrees Fahrenheit) and reusing them three times, at least 75% of the PFOA was removed in subsequent tests.

Eager to gain a deeper understanding through further experimentation, the researchers aim to increase the efficiency of the process by refining it further.

This three-hour timetable is also compatible with existing water treatment systems.

Application promise

"Currently, these chemicals are not strongly regulated in the UK in drinking water, but there are guidelines, and we expect changes in policy quite soon. Water companies are likely to be looking at integrating systems to deal with them," co-author Professor Davide Mattia said

The U.S. Environmental Protection Agency (EPA) issued the first legally enforceable national drinking water standards for several common types of PFAS in April 2024.

"These are good efficiency rates," Hugo Carronnier, a project manager specializing in PFAS at pollution control company Valgo, told Euronews Next. "It's promising, we'll have to see how it develops in the future because it's currently on a laboratory scale."

(The elimination technique for wastewater treatment developed by Valgo reaches a 98 to 99% removal rate of PFAO.)

The research team will next study the removal of different PFAS and further increase the filters' yield and speed of absorption.

The team, which includes Alysson Martins, Liana Zoumpouli, Antonio Jose Exposito, Jannis Wenk, and Davide Mattia, recently published their findings in The Chemical Engineering Journal.