Look around you. How many PET bottles have you used today? One, two, maybe none? I hope not for bottled water. Well, you've certainly accumulated some over the course of the week. If you're wondering where they'll end up (you responsibly throw them in the recycling bin, right?), there are those who are racking their brains to find a way to actually make them disappear. Not "disappear" in the sense of "sweep under the rug," as we've been doing for decades, but transform them into something useful. And now researchers at Northwestern University have pulled an idea out of a hat that makes traditional recycled PET chemistry seem like a medieval procedure: using humidity in the air. Yes, you read that right. The air you breathe.
The PET Problem and Its “Elegant” Solution
Let's start with two facts. Do you know who is the world's leading producer of plastic pollution per capita? The United States. Do you know how much recycled PET our friends overseas produce? Only 5%.
PET (polyethylene terephthalate) represents 12% of the plastic used globally, mainly in bottles and food packaging. And this is where the research published on Green chemistry, Led by Yosi Kratish e Tobin J. Marks of Northwestern University.
Instead of using extreme temperatures, toxic solvents and energy-intensive processes, these scientists came up with something much simpler: a molybdenum catalyst (economical and non-toxic) and Activated carbon. They heat the mix with the PET and, after the chemical bonds break, they expose it to air. The atmospheric humidity does the rest, transforming the plastic into terephthalic acid (TPA), a valuable monomer that can be reused for new products.
Extraordinary results and future prospects
“What’s particularly exciting about our research is that we’ve used humidity in the air to break down plastics, resulting in an exceptionally clean and selective process. By recovering the monomers, which are the basic building blocks of PET, we can recycle them or even transform them into higher-value materials.”
The numbers are staggering: in just 4 hours, The process recovers 94% of the possible TPA. The catalyst is reusable without losing its effectiveness. And it even works with mixed plastics, dyes and real products like bottles and fabrics, converting them into pure, colorless TPA.
Naveen Malik, first author of the study and now a researcher at the SRM Institute of Science and Technology in India, points out how the atmosphere contains on average 10.000-15.000 cubic kilometers of water, a perfect amount for this reaction. “Too much water would stop the process,” he explains. Kratish.
“It’s a delicate balance, but it turns out that the amount of water in the air is exactly what is needed to produce recycled PET.”
Recycled PET, towards a new idea of circular economy?
I like to think that this discovery could represent a paradigm shift towards a true circular economy. The team is now working to scale the process to an industrial level. No more microplastics in our oceans? It may be premature to say, but the direction is the right one.
In a world where complex solutions often generate new problems, this simplicity is disarming: air, a cheap catalyst and an elegant chemical reaction. Three elements that could change the fate of millions of plastic bottles.
