The U.S. Can Step Down as Top Plastic Polluter as Scientists Present a New Simpler Method to Break Down Plastic

Plastic pollution is a huge problem in the U.S. The biggest issue the authorities face regarding this material is its breakdown, stated Phys.org. The present processing procedure allows only a tiny amount of plastics to be recycled. A team of experts has come up with a new method to elevate the quantity as well as the quality of recycling. This method has been described in detail in a study published in Green Chemistry. 

The objective of researchers associated with the study was to develop a method that would reduce plastic waste into non-toxic byproducts. "The U.S. is the number one plastic polluter per capita, and we only recycle 5% of those plastics," said Northwestern's Yosi Kratish, the study's co-corresponding author. "There is a dire need for better technologies that can process different types of plastic waste. Most of the technologies that we have today melt down plastic bottles and downcycle them into lower-quality products."

Researchers associated with the study focused on polyethylene terephthalate (PET) because it is the most commonly used plastic in the polyester family. It does not break down easily and eventually becomes a huge contributor to worldwide plastic pollution.  The current methods in place to process these plastics involve extreme conditions like high temperatures, expensive catalysts, and solvents which result in harmful byproducts. Even after the complex processing is completed, the process of separating recycled materials from solvents is time-consuming and demands a lot of energy. 

The team decided to make a processing method that did not involve solvents at all. "Using solvents has many disadvantages," Kratish said. "They can be expensive, and you have to heat them up to high temperatures. Then, after the reaction, you are left with a soup of materials that you have to sort to recover the monomers. Instead of using solvents, we used water vapor from the air. It's a much more elegant way to tackle plastic recycling issues."

Firstly, a molybdenum catalyst was utilized to break the bonds of polyethylene terephthalate (PET). The catalyst is also an improvement on existing methods as it is cheaper than the past counterparts. The catalyst combined with activated carbon to facilitate the breakdown. Thereafter the resultant products were exposed to ambient air.

The moisture present in the air allows the broken-down PET to be changed into monomers. Monomers are the basic unit of plastics, and researchers think that these monomers can later be used to make other PET products. "Air contains a significant amount of moisture, making it a readily available and sustainable resource for chemical reactions," said Naveen Malik, the study's first author. "On average, even in relatively dry conditions, the atmosphere holds about 10,000 to 15,000 cubic kilometers of water. 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," said Malik, stated Phys.org. 

In just four hours, 94% of the possible terephthalic acid (TPA) from PET was extracted. TPA is the precursor of polyester. The only byproduct of the process was acetaldehyde, an easy-to-remove industrial chemical. Researchers were ecstatic to formulate a method that employed steps that were less toxic than the ones employed before. "What's particularly exciting about our research is that we harnessed moisture from the air to break down the plastics, achieving an exceptionally clean and selective process. By recovering the monomers, which are the basic building blocks of PET, we can recycle or even upcycle them into more valuable materials," Kratish shared. 

Experts further claimed that their processing not only did not lead to harmful products but also was practical in approach. "Our study offers a sustainable and efficient solution to one of the world's most pressing environmental challenges: plastic waste," Malik shared. "Unlike traditional recycling methods, which often produce harmful byproducts like waste salts and require significant energy or chemical inputs, our approach uses a solvent-free process that relies on trace moisture from ambient air. This makes it not only environmentally friendly but also highly practical for real-world applications," said the author, stated Phys.org.

The method was determined to be fast as well as efficient. The process gave fruitful results even with shirts, plastic bottles, and mixed plastic waste. "Our technology has the potential to significantly reduce plastic pollution, lower the environmental footprint of plastics, and contribute to a circular economy where materials are reused rather than discarded," Malik said. "It's a tangible step toward a cleaner, greener future, and it demonstrates how innovative chemistry can address global challenges in a way that aligns with nature." Researchers now aim to enlarge the scale of this process and use it in the industrial context.