scientists recycle plastic bags into glowing sensors that detect toxic metals in drinking water

"The process starts with polyethylene, which is the main plastic used in shopping bags. The researchers convert it into very small particles called carbon quantum dots, or CQDs. These particles are smaller than a virus, and to produce them, the team uses a combination of two methods: pyrolysis and hydrothermal treatment. Pyrolysis involves heating the plastic without oxygen, while hydrothermal treatment involves heating the material in water under pressure."

"The researchers then add less than seven percent hydrogen peroxide to help break down the polyethylene, and the full process takes about ten hours. The result is a solution containing the carbon quantum dots (CQDs), which light up under UV light and become fluorescent. The light emission happens because of the structure of the carbon atoms and the chemical groups attached to the surface of the CQDs, so when the UV light hits the"

"The glow from the recycled plastic bags can help find toxic metals in drinking water as sensors. Weaker light means more toxic metals in the water, and if the glow is strong, it means that there are fewer or no metals in the water. The scientists from Universitas Gadjah Mada and Hokkaido University explain that the carbon quantum dots (CQDs) have oxygen groups on their surface that can attach to certain metals."

Polyethylene from shopping bags is converted into carbon quantum dots (CQDs) using pyrolysis and hydrothermal treatment. Less than seven percent hydrogen peroxide is added to assist polyethylene breakdown, and the full process takes about ten hours. The resulting CQD solution fluoresces under UV light because carbon atom structure and surface chemical groups allow electrons to be excited and then release visible light as they return to lower energy states. Surface oxygen groups bind certain metal ions, producing a quenching effect. The CQDs reacted selectively with ferric ions, so weaker fluorescence indicates higher iron concentration in drinking water.

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