Northwestern University chemists have developed a new method to break down plastic waste using moisture from the air. This process targets polyethylene terephthalate (PET), a common plastic in the polyester family, and converts it into monomers, which are essential for creating new PET products or higher-value materials.
The research team uses an inexpensive catalyst to dismantle PET bonds, followed by exposure to ambient air. The moisture in the air facilitates the conversion of broken-down PET into monomers. "The U.S. is the number one plastic polluter per capita, and we only recycle 5% of those plastics," said Yosi Kratish, co-corresponding author of the study. Kratish emphasized the need for better technologies that can handle various types of plastic waste.
Naveen Malik, the study's first author, highlighted that their method avoids harmful byproducts associated with traditional recycling techniques: "Our approach uses a solvent-free process that relies on trace moisture from ambient air."
Kratish and Tobin J. Marks led this study at Northwestern University. Malik was a postdoctoral fellow during this research and is now affiliated with SRM Institute of Science and Technology in India.
The process effectively recovers 94% of monomers from PET within four hours without producing toxic byproducts. It utilizes molybdenum catalyst and activated carbon, both non-toxic materials. The method also works with mixed plastics without requiring prior sorting.
This innovation presents significant advantages over existing methods by eliminating expensive solvents and reducing energy input. When tested on real-world materials like plastic bottles and shirts, it proved effective even with colored plastics.
Researchers aim to scale up this process for industrial use to tackle vast quantities of plastic waste efficiently. "Our technology has the potential to significantly reduce plastic pollution," Malik stated.
This study was published in Green Chemistry journal and supported by the U.S. Department of Energy.