Why in news?

Chemists in the United States and China said they had finally found a breakthrough method to degrade the polluting compounds, referred to as PFAS, using relatively low temperatures and common reagents.

Highlights:

• “Forever chemicals” used in daily items like non-stick pans have long been linked to serious health issues — a result of their toxicity and extreme resistance to being broken down as waste products.
• Their results were published in the journal Science, potentially offering a solution to a longstanding source of harm to the environment, livestock and humans.

What are PFAS?

• PFAS, or per- and poly fluoro alkyl substances, were first developed in the 1940s . According to the US Centre for Disease Control and Prevention (CDC), PFAs are man-made chemicals used to make nonstick cookware, water-repellent clothing, stain-resistant fabrics, cosmetics, firefighting forms and many other products that resist grease, water and oil.
• PFAs can migrate to the soil, water and air during their production and use. Since most PFAs do not break down, they remain in the environment for long periods of time. Some of these PFAs can build up in people and animals if they are repeatedly exposed to the chemicals.
• Over time, the pollutants have accumulated in the environment, entering the air, soil, groundwater and lakes and rivers as a result of industrial processes and from leaching through landfills.

Impact of PFAS

• A study published last week by Stockholm University scientists found rainwater everywhere on the planet is unsafe to drink because of PFAS contamination.
• Chronic exposure to even low levels has been linked to liver damage, high cholesterol, reduced immune responses, low birth weights and several kinds of cancer.
• Recent research has also revealed that long-term low-level exposure to certain PFAs can make it difficult for humans to build antibodies after being vaccinated against various diseases.

Destroying PFAS

• Current methods to destroy PFAS require harsh treatments, such as incineration at extremely high temperatures or irradiating them with ultrasonic waves.
• PFAS’ indestructability comes from their carbon-flouride bonds, one of the strongest types of bonds in organic chemistry. Fluorine is the most electronegative element and wants to gain electrons, while carbon is keen to share them.
• PFAS molecules contain long chains of these bonds, but the research team was able to identify a glaring weakness common to a certain class of PFAS.
• At one end of the molecule, there is a group of charged oxygen atoms which can be targeted using a common solvent and reagent at mild temperatures of 80-120 degrees Celsius, decapitating the head group and leaving behind a reactive tail.
• A second part of the study involved using powerful computational methods to map out the quantum mechanics behind the chemical reactions the team performed to destroy the molecules.

More than 12,000 PFAS chemicals

• The current study focused on 10 PFAS chemicals including a major pollutant called GenX, which for example has contaminated the Cape Fear River in North Carolina, a water source for 350,000 people.the US Environmental Protection Agency has identified more than 12,000 PFAS chemicals.