In context: Forever chemicals are a group of synthetic compounds which don't gets easily broken down in the environment. They persist and accumulate in soil, wildlife, and water, causing some serious health issues for decades. The industry is trying to develop new methods to safely dispose of PFAS, but their chemical structure is an extremely hard issue to deal with.
A team at Rice University has developed a new material for filtering per- and polyfluoroalkyl substances (PFAS). Also known as "forever chemicals," these synthetic compounds have been widely used in many products since the invention of Teflon in 1938. PFAS coatings can resist heat, water, oil, and stains. Unfortunately, they have also been linked to several types of cancer and can have detrimental effects on pregnancy and child development.
The Rice team described their new technology in a recently published study. This layered double hydroxide (LDH) material – a mix of copper and aluminum – can apparently absorb long-chain PFAS 100 times faster than traditional filtration systems. Even better, it may help completely destroy most traces of these cancer-inducing chemicals.
Current filtration technology can capture PFAS in water, but the compounds must then be stored in specialized waste facilities before they can be destroyed. Total disposal involves an intensive thermal process, with temperatures high enough to break larger PFAS into smaller compounds. A system designed to completely destroy PFAS at an industrial scale does not yet exist.
LDH is a variation of existing anti-PFAS solutions, where some aluminum atoms are replaced by copper atoms. The compound is positively charged, allowing it to bind more easily with negatively charged PFAS chains. Thanks to its chemical configuration, LDH can "soak up" PFAS up to 100 times faster than competing filtration methods.
Researchers warn that PFAS are often considered "indestructible" because of the strong bond between carbon and fluorine atoms. However, these bonds can be broken when the material is heated at a relatively mild temperature of 400 – 500°C. Fluoride is then trapped in the LDH and bound to calcium. The resulting calcium fluoride compound should be safe to dispose of in a common landfill.
This "total destruction" process is effective against some of the most common long-chain PFAS pollutants, while LDH can only absorb some smaller, more widespread PFAS compounds.
According to Michael Wong, director of the PFAS Research Center at Rice University's Water Institute, the new material could potentially be engineered to capture a wider range of PFAS. PFAS researcher Laura Orlando explained: "We're going to need as many technologies as we can possibly find to deal with PFAS in drinking water, and if this works to scale on wastewater, then it would be really something to pay attention to."