Scientists Develop New Method to Recycle Plastics Using Air Moisture

The catalyst is not only durable but also recyclable, maintaining its effectiveness through repeated use.

SEATTLE (Scrap Monster): In what could be a fix to the world’s plastic problem, researchers have developed a simple new method of harnessing moisture from air to breaking down the waste.

The process begins with an inexpensive catalyst that breaks down the bonds in polyethylene terephthalate (PET), the most widely used plastic in the polyester family. Once broken, the material is simply exposed to ambient air to transfer PET into monomers—the essential building blocks of plastics.
Researchers believe these monomers could then be recycled or upcycled into more valuable materials.

The new technique, which is safer, cheaper, and more sustainable than current plastic recycling methods, offers a promising path toward creating a circular economy for plastics.

“What’s particularly exciting about our research is that we harnessed moisture from air to break down the plastics, achieving an exceptionally clean and selective process,” Yosi Kratish, who is also the co-corresponding author of the study, said in a press release.

Sustainable solution

The researchers utilized a molybdenum catalyst and activated carbon—both of which inexpensive, abundant, and non-toxic.

To begin the process, they combined PET with the catalyst and activated carbon and then heated up the mixture. Polyester plastics consist of large molecules with repeating units linked by chemical bonds. Within a short time, these bonds broke apart.

Next, the researchers exposed the fragmented material to air. With just a trace of moisture, it transformed into terephthalic acid (TPA), a highly valuable precursor for polyesters. The only byproduct was acetaldehyde, an easily removable industrial chemical with commercial value.

“On average, even in relatively dry conditions, the atmosphere holds about 10,000 to 15,000 cubic kilometers of water,”  Naveen Malik, the study’s first author, said.

“Leveraging air moisture allows us to eliminate bulk solvents, reduce energy input and avoid the use of aggressive chemicals, making the process cleaner and more environmentally friendly.”

Kratish stated that the system worked flawlessly but failed when extra water was added, as the excess disrupted its function. Maintaining the right balance was crucial, and ultimately, the natural moisture in the air provided the perfect amount.
The plastic problem

PET plastics —widely used in food packaging and beverage bottles — account for 12% of global plastic consumption. It is a major contributor to plastic pollution due to its resistance to natural degradation. After use, it either ends up in landfills or degrades into tiny microplastics or nanoplastics, polluting wastewater and waterways.

Recycling plastic remains a key focus in research, but existing methods often rely on extreme conditions—such as high temperatures, intensive energy use, and harsh solvents—that produce toxic byproducts.

Moreover, catalysts like platinum and palladium are expensive and contribute to the waste problem. Once the reaction is complete, researchers must separate the recycled materials from the solvents—a process that is both time-consuming and energy-intensive

“Instead of using solvents, we used water vapor from air. It’s a much more elegant way to tackle plastic recycling issues,” Kratish said.
Fast and efficient
The process is both fast and efficient, recovering 94% of the possible TPA within just four hours.

The catalyst is not only durable but also recyclable, maintaining its effectiveness through repeated use. Moreover, the method is designed to work with mixed plastics, selectively targeting polyesters for recycling. This selectivity eliminates the need for pre-sorting, offering a significant economic advantage to the recycling industry.

When tested on real-world materials such as plastic bottles, clothing, and mixed plastic waste, the process remained highly effective, even breaking down colored plastics into pure, colorless TPA.

Moving forward, the researchers aim to scale up the process for industrial applications, ensuring it can efficiently manage large volumes of plastic waste.

The study was recently published in Green Chemistry, a journal published by the Royal Society of Chemistry.

 Courtesy: www.obrag.org

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