Experts estimate that the global production and disposal of plastics emits nearly 2 billion tons of greenhouse gases per year. The vast majority of these materials end up in landfills, but what if we could repurpose some of that waste to remove planet-warming emissions from the atmosphere?
A team of researchers in Denmark has discovered a way to do just that. In a new study, published September 5 in the journal Science Advances, they transformed decomposed #1 plastic—also known as PET (polyethylene-terephthalate) plastic—into an efficient carbon capture material.
“The beauty of this method is that we solve a problem without creating a new one,” lead author Margarita Poderyte, a chemistry PhD candidate at the University of Copenhagen, said in a release. “By turning waste into a raw material that can actively reduce greenhouse gases, we make an environmental issue part of the solution to the climate crisis.”
Two big problems, one innovative solution
As global temperatures rise, the need to mitigate planet-warming pollutants—such as carbon dioxide—is increasingly urgent. This has led scientists to develop ways to actively remove CO2 from the atmosphere in addition to cutting emissions. At the same time, the growing amount of plastic waste in landfills, oceans, and pretty much everywhere else on Earth has led to a global microplastics crisis that threatens human and ecosystem health.
Poderyte and her colleagues hope their new approach to carbon capture can kill two birds with one stone. Through a chemical reaction known as aminolysis, they upcycled PET plastic—mainly used in plastic bottles and food packaging—into a CO2 sorbent called BAETA.
This material has a powdery structure that can be made into pellets that are very effective at grabbing CO2 molecules. One pound of BAETA can absorb up to 0.15 pounds of CO2, which is quite efficient compared to most current commercial systems.
BAETA is also more heat-resistant than other amine sorbents, remaining stable at temperatures up to 482 degrees Fahrenheit (250 degrees Celsius). However, it requires a greater thermal energy input to reach maximum CO2 absorption and to release the captured carbon for storage or conversion to other resources. This may lead to greater energy costs, but the researchers believe BAETA can provide a scalable, cost-effective carbon capture system.
Tapping a perniciously abundant resource
Humans produce immense amounts of PET plastic waste, much of which accumulates in oceans. Researchers recently discovered 27 million tons of plastic particles floating in the North Atlantic, the ecosystem impacts of which are still largely unknown.
“If we can get our hands on the highly decomposed PET plastic floating in the world’s oceans, it will be a valuable resource for us as it’s so well suited for upcycling with our method,” Poderyte said. She and her colleagues hope BAETA can help eliminate marine plastic pollution while also tackling the climate crisis.
“We’re not talking about stand-alone issues, nor will the solutions be,” co-author Jiwoong Lee, an associate professor of chemistry at the University of Copenhagen, said in the release. “Our material can create a very concrete economic incentive to cleanse the oceans of plastic.”