How to destroy a ‘forever chemical’ PFAS

How to destroy a ‘forever chemical’ PFAS

Subject :Environment

Section: Pollution

Context Scientists discovering ways to eliminate perfluoroalkyl and polyfluoroalkyl substances, but this growing global health problem isn’t going away soon

What are PFAS chemicals?

• PFAS chemicals seemed like a good idea at first. As Teflon, they made pots easier to clean starting in the 1940s. They made jackets waterproof and carpets stain-resistant.
• Food wrappers, firefighting foam, even make-up seemed better with perfluoroalkyl and polyfluoroalkyl substances.

Bad Effects

• Then tests started detecting PFAS in people’s blood.
• Today, PFAS are pervasive in soil, dust and drinking water around the world. Studies suggest they’re in 98 per cent of Americans’ bodies, where they’ve been associated with health problems including thyroid disease, liver damage and kidney and testicular cancer. There are now over 9,000 types of PFAS.
• They’re often referred to as “forever chemicals” because the same properties that make them so useful also ensure they don’t break down in nature.

Solution

• The latest breakthrough, published August 18, 2022, in the journal Science, shows how one class of PFAS can be broken down into mostly harmless components using sodium hydroxide, or lye, an inexpensive compound used in soap. It isn’t an immediate solution to this vast problem, but it offers new insight.

How do PFAS get from everyday products into water, soil and eventually humans?

• There are two main exposure pathways for PFAS to get into humans — drinking water and food consumption.
• PFAS can get into soil through land application of biosolids, that is, sludge from wastewater treatment, and can they leach out from landfills. If contaminated biosolids are applied to farm fields as fertilizer, PFAS can get into water and into crops and vegetables.
• For example, livestock can consume PFAS through the crops they eat and water they drink.
• The problem is that these chemicals are everywhere, and there is no natural process in water or soil that breaks them down.Many consumer products are loaded with PFAS, including makeup, dental floss, guitar strings and ski wax.

How are remediation projects removing PFAS contamination now?

• Methods exist for filtering them out of water. The chemicals will stick to activated carbon, for example. But these methods are expensive for large-scale projects, and you still have to get rid of the chemicals.

What are the most promising methods scientists have found for breaking down PFAS?

• The most common method of destroying PFAS is incineration, but most PFAS are remarkably resistant to being burned. That’s why they’re in firefighting foams.
• PFAS have multiple fluorine atoms attached to a carbon atom, and the bond between carbon and fluorine is one of the strongest. Normally to burn something, you have to break the bond, but fluorine resists breaking off from carbon.
• Most PFAS will break down completely at incineration temperatures around 1,500 degrees Celsius (2,730 degrees Fahrenheit), but it’s energy intensive and suitable incinerators are scarce.
• A group at Battelle has developed supercritical water oxidation to destroy PFAS. High temperatures and pressures change the state of water, accelerating chemistry in a way that can destroy hazardous substances. However, scaling up remains a challenge.