Farewell to ‘forever’ – destruction of PFAS by milling with a new additive – ScienceDaily

Farewell to ‘forever’ – destruction of PFAS by milling with a new additive – ScienceDaily

Per- and polyfluoroalkyl substances (PFAS) are potentially harmful substances known as “forever chemicals” because they are so difficult to destroy. An emerging technique for breaking down PFAS is to forcibly grind them with metal balls in a moving container, but this technique may require corrosive additives. Well, researchers in ACS’ Letters on Environmental Science and Technology report a new type of “ball milling” additive that completely degrades PFAS at ambient temperature and pressure.

Solid PFAS contamination is a constant problem for soil near landfills, manufacturing plants and facilities that frequently use fire-fighting foam. Currently, the US Environmental Protection Agency recommends incineration to destroy these substances, but concerns remain as to whether this energy-intensive method is effective in preventing pollution.

Another option is ball milling, a process that mixes PFAS and additives with metal balls at high speeds. Collisions between the bullets and additives create solid state reactions that break the carbon-fluorine bonds on PFAS and convert them into less harmful products. A common additive for this process is potassium hydroxide (KOH), but it forms problematic clumps and is corrosive. To overcome these limitations, Yang Yang and colleagues turned to boron nitride, a piezoelectric material that generates partial electrical charges and can accept electrons when deformed by mechanical forces. They now report a ball milling process that uses boron nitride as a non-corrosive additive to react with and destroy PFAS.

As a proof of concept for the new additive, the team ball milled two legacy PFAS compounds with boron nitride and analyzed the products. By optimizing the ratio of boron nitride to PFAS, the team almost completely removed the fluorine atoms from PFAS in four hours at ambient temperature and pressure, effectively destroying it. The process also degraded 80% of known PFAS from soil contaminated with firefighting foam after six hours. In both experiments, boron nitride degraded PFAS more efficiently than using KOH. Further analysis suggests that boron nitride accepts electrons and fluorine atoms from PFAS, which then breaks down into fluoroalkyl radical species that react with oxygen or other radicals to eventually produce harmless minerals. This new method could open the door to future mechanical force-based PFAS remediation strategies, the researchers say.

Leave a Reply

Your email address will not be published. Required fields are marked *