By Deborah Kotob 

Once again, the impressive power of light is in science news. Recent research has uncovered the ability of the absorption of visible light by a catalyst, to break down PFAS (forever chemicals) and render them harmless. Perfluorinated polymers (PFs) chemicals came on the scene when Dr. Roy J. Plunkett invented Teflon in 1938. The stability, water resistance and heat resistance made PFASs and PFs ideal for cookware, firefighting foam and clothing, their stability, and resistance to water and heat. But these same properties mean they do not decompose unless exposed to extreme temperatures of 400 degrees centigrade.

Consequently, PFAS have been found in the water, soil and the bodies of humans where they cause hormonal disruptions and have carcinogenic effects. According to The Endocrine Society at endocrine.org, PFAS chemicals can affect our biology by mimicking fatty acids—the building blocks of fat in our bodies as well as the foods we eat. They also act as endocrine-disrupting chemicals (EDCs) due to their ability to interfere with hormone systems. Exposure to PFAS chemicals can cause adverse health effects. Studies conducted near Parkersburg, W. Va., found a probable link between perfluorooctanoic acid (PFOA) exposure and six disease categories: diagnosed high cholesterol, thyroid disease, ulcerative colitis, testicular cancer, kidney cancer and pregnancy-induced hypertension.

PFASs and PFs wind up in landfills where they pose future contamination risks. Currently, these chemicals have been found in drinking water supplies, food and even in the soil of Antarctica. While there are plans to phase out PFAS production, the problem remains how to break them down to a benign substance. Researchers at Ritsumeikan University employed a photocatalytic method using visible light to break down PFAS and PFs, but also to recover and recycle fluorine in the process. Fluorine is a critical component in many industries, from pharmaceuticals to clean energy technologies. By recovering fluorine from waste PFAS, they reduce reliance on fluorine production and create a sustainable recycling process. 

Their study, published in the journal Angewandte Chemie International Edition on 19 June 2024, details a photocatalytic method that uses visible light to break down PFAS and other fluorinated polymers (FPs) at room temperature into fluorine ions. Using this method, the researchers achieved 100 percent defluorination of perfluorooctanesulfonate (PFOS) within just eight hours of light exposure.

Photocatalyst is a combination of two words: photo related to photon and catalyst, a substance that alters the reaction rate in its presence. Photocatalysts are materials that absorb light and act as a semi-conductor, changing the rate of a chemical reaction when exposed to light. Photocatalytic technology has a low cost, excellent sustainability, high efficiency and low environmental impact. Photocatalytic technology can efficiently degrade and eventually convert to non harmful minerals. Photocatalysts are materials which decompose detrimental substances under sunlight containing UV rays. 

Currently the predominant photocatalyst used in environmental cleanup is hybrid titanium dioxide TiO2, a non-toxic environmentally friendly and reusable photocatalyst. Photocatalysis includes reactions that take place by utilizing light and a semiconductor, a substrate that absorbs light and acts as a catalyst for chemical reactions. Photocatalysis is promising for many types of environmental remediation, particularly water purification and destroying wastewater contaminants. It has successfully degraded microorganisms and non-organic substances like dyes and chemicals in water.

Originally published in 20/20 Magazine.