LED Light Breaks Down Forever Chemicals that Harm the Environment

The durability of per- and polyfluoroalkyl substances (PFAS) has led to their widespread use in medical, industrial, and commercial settings throughout the world. These “forever chemicals” are made of inorganic materials that break down very slowly. They are difficult to dispose of, and over time, have become part of the natural environment. According to the U.S. Environmental Protection Agency (EPA), exposure to PFAS in the water, air, and soil can lead to cancer, reproductive issues, and other health problems in humans.

A photocatalyst system based on LED light, developed by researchers at Colorado State University (CSU), shows promise in breaking down the carbon-fluorine (C-F) bonds that are especially challenging to dismantle in PFAS. The photoredox catalyst system reduces C-F bonds to generate carbon-centered radicals, which can then be intercepted for hydrodefluorination and cross-coupling reactions.

Photoredox catalysts are materials that can absorb light and generate electron transfer reactions in response to irradiation. A photoredox catalyst system uses light energy, which is more sustainable than traditional energy sources, to drive chemical reactions.

Chemistry researchers work in the Miyake Lab at Colorado State University. The researchers developed a photoredox catalyst system to break down PFAS, the forever chemicals that are everywhere in the environment. Courtesy of Colorado State University.

The LED-based photocatalytic system developed at CSU can be used at room temperature. Ambient temperatures allow chemical reactions to be generated under relatively mild conditions and make it possible to produce chemicals faster and in fewer steps. Traditional chemical manufacturing processes typically require high temperatures to achieve similar results.

The team’s approach to driving chemical transformations through light energy is inspired by natural processes like photosynthesis.

“Our approach is a fundamental advancement in organic synthesis that achieves activation of these challenging carbon-fluorine bonds across a variety of situations,” professor Garret Miyake said. “Our method is more sustainable and efficient and can be used to address stubborn compounds in plastics, for example, in addition to the obvious uses around PFAS.”

Miyake serves as director of the National Science Foundation-funded Center for Sustainable Photoredox Catalysis (SuPRCat) at CSU. SuPRCat was formed in 2023 with a goal of developing chemical manufacturing processes that harness light energy and use readily available materials as catalysts.

In addition to its work on a photocatalytic system to break down C-F bonds in forever chemicals, SuPRCat is exploring other ways to make the chemical manufacturing industry more ecological.

“Our approach in SuPRCat to using LED lights presents a host of possibilities towards achieving these reactions in a more sustainable and efficient way,” researcher Xin Liu said. “From dealing with plastics that don’t degrade quickly to improving the manufacturing process of needed fertilizers, this is a key area and something CSU is well positioned to lead on.”

The next challenge for the researchers will be to prepare the photoredox catalyst system for broad application in the field.

“We need to make this technology more practical so it can be used in water or soil — places where PFAS are found,” researcher Mihai Popescu said. “We need the chemistry we are showcasing here to be useful in those conditions, and that is where a lot of work remains.”

Most people in the world have been exposed to PFAS because these chemicals are ubiquitous in the materials that comprise everyday life, including clothing, food, water, and medicine. Forever chemicals affect every aspect of modern life and have a negative impact on the environment. The researchers hope that their work will contribute to a more efficient and sustainable approach to the manufacture and management of chemical materials at the industrial scale.

The research was published in Nature (www.doi.org/10.1038/s41586-024-08327-7).