In a potential game-changer for tackling the global plastic crisis, scientists have discovered a straightforward and eco-friendly method that uses moisture from the air to decompose plastic waste.
The technique begins with a low-cost catalyst that breaks the molecular structure of polyethylene terephthalate (PET)—a commonly used plastic in the polyester family. Once broken down, the plastic is exposed to ambient air, triggering a transformation into monomers, the fundamental units that make up plastics.
Researchers suggest these monomers can then be reused or converted into higher-value materials, offering a more sustainable route for plastic recycling. Unlike current recycling methods, which are often costly and environmentally damaging, this new approach is safer, more affordable, and cleaner—potentially paving the way for a circular plastic economy.
“What sets our study apart is that we used air moisture to break down plastic, making the process highly selective and efficient,” said Yosi Kratish, a co-author of the study.
A Cleaner, Greener Process
The team used a molybdenum-based catalyst along with activated carbon—both inexpensive and environmentally benign. The process starts by mixing PET with the catalyst and carbon, then heating the mixture. Polyester plastics are made of repeating chemical units, and the heat breaks the bonds linking them.
After the breakdown, the fragments are exposed to ambient air. Even minimal humidity in the air is enough to convert the plastic into terephthalic acid (TPA), a valuable component for making new polyesters. The only byproduct is acetaldehyde, an industrial chemical that is easy to extract and has commercial use.
“Even in dry climates, the atmosphere carries 10,000 to 15,000 cubic kilometers of water vapor,” noted lead author Naveen Malik. “Tapping into that moisture lets us avoid harsh solvents and high energy use, making the method both sustainable and practical.”
However, Kratish emphasized that balance is key. Adding extra water disrupted the process, while natural air moisture proved to be just right.
Addressing a Major Pollution Source
PET plastics—commonly found in beverage bottles and food packaging—make up around 12% of global plastic use. Because PET doesn’t break down easily in nature, it contributes heavily to environmental pollution, often ending up as microplastics in oceans and rivers.
Traditional recycling methods often depend on extreme heat, strong chemicals, and expensive metals like platinum and palladium, which create harmful byproducts and waste. Separating recycled material from solvents further complicates and slows the process.
“In our method, we use water vapor from the air instead of harmful solvents. It’s a much more refined and environmentally conscious approach,” Kratish said.
Promising Results and Industrial Potential
This new technique is both rapid and efficient—recovering up to 94% of usable TPA in just four hours. The catalyst is durable and reusable, making it suitable for long-term application. Even better, it can target polyester within mixed plastic waste without the need for sorting, a major cost-saver for recycling facilities.
When tested on actual plastic waste, including bottles, textiles, and colored plastics, the process consistently produced pure, colorless TPA, showcasing its reliability and adaptability.
The team now plans to scale the technology for industrial use to manage larger volumes of plastic waste efficiently. Their findings were recently published in Green Chemistry, a journal by the Royal Society of Chemistry.