Scientists use LED visible light to 100% decompose permanent chemicals

"Permanent chemicals" are widely used and have excellent stability, heat resistance and waterproofness. However, as the name suggests, they will not decompose naturally and will "forever" remain in the environment. They are also worrying toxic pollutants. But now Japanese scientists have found a solution to quickly decompose permanent chemicals at room temperature, and 100% of certain types of permanent chemicals can be decomposed overnight.

The so-called permanent chemicals are perfluoro/polyfluoroalkyl substances (PFAS). Thanks to the strong carbon-fluorine bond, their applications range from non-stick pans, firefighting foams and waterproof clothing. However, since these substances will only decompose at temperatures above 400°C, some will still flow into landfills and remain in the environment. When these substances accumulate in the human body, they are associated with diabetes, fertility problems, various cancers, immune system damage and many other health conditions. For

this reason, scientists are also working hard to solve the negative effects of convenient life. Scientists at Ritsumeikan University in Japan have proposed a new method. Through visible LED light and a temperature of 38°C, one of the PFAS: perfluorooctane sulfonate (PFOS) can be 100% decomposed in 8 hours, and 81% of the fluorinated polymer Nafion can be decomposed within 24 hours.

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The new method can recover fluorine from PFAS and reduce the demand for new fluorine production. Professor Yoichi Kobayashi, the main author of the study, said that the new method is expected to effectively decompose various perfluoroalkyl substances under mild conditions and establish a sustainable fluorine recycling society.

This technology is based on photocatalytic reactions. The researchers added 0.8 mg of cadmium sulfide (CdS) nanocrystals, 20 mg of the compound triethanolamine (TEOA), and 0.65 mg of PFOS to be treated to 1 ml of water. The

solution was then exposed to 405 nm LED light to trigger a photocatalytic reaction. The light excites the nanoparticles to produce electron-hole pairs, causing PFOS molecules to adsorb on the nanoparticles, remove fluoride ions from PFAS molecules, and destroy the strong carbon-fluorine bonds.

The team pointed out that this technology is similar to many catalysts that decompose PFAS molecules, but does not require ultraviolet rays and requires lower temperatures. The technology can also recover fluoride ions and reuse them for other industrial applications. Kobayashi said that this technology will also contribute to the development of fluorine recovery technology. (Source: Science and Technology News)