Made from a common type of plastic, scientists have designed a carbon capture material which aims to solve two environmental crises at once: plastic pollution and global warming.
Polyethylene Terephthalate (PET) is one of the most widely produced plastics in the world, commonly used for food and drinks packaging. It is recyclable, but 85-90% of it ends up being incinerated or in landfill.
A team from the University of Copenhagen have designed a new miracle material using PET which can pull greenhouse gas out of the atmosphere. It’s called BAETA, and has been shown to be chemically simple to produce, markedly efficient at carbon dioxide removal, and extremely durable.
Transforming plastic waste into BAETA is surprisingly straightforward. The process, called PET aminolysis, requires no catalysts or solvents. Reporting the group's findings, published in Science Advances, Margarita Poderyte describes a "one step reaction that work[s] even at room temperature (but is faster if we heat it up)."
BAETA captures CO2 as a solid and does not require water usage or other solvents. The fact it works in solid state is a key advantage over other systems, making it effective in a range of real world contexts, from flue gas (typical exhaust fumes emitted from a power station consisting of 5-20% CO2 at a temperature of 120-170 °C), to ambient air (~0.04% CO2), and across a range of humidity levels.
Furthermore, BAETA is thermally stable up to ~220-250°C and maintains performance after hot-air exposure (100 °C) and after boiling in water for 48 hours. The highly resilient material demonstrates no loss in performance after 40-150 high-temperature cycles, critical for long term use.
These unique properties give it a significant edge over existing carbon capture materials, such as monoethanolamine (MEA). A liquid at room temperature, MEA is thermally and oxidatively unstable. It loses water through evaporation and needs to be constantly recharged. BAETA, on the other hand, is a solid that maintains its stability and does not require water usage, giving it a major advantage.
Furthermore, MEA works best for high-concentration CO2 streams like flue gas, whereas BAETA has been shown to be effective for direct air capture as well.
Another key benefit is that BAETA can absorb CO2 at around 150°C and desorb it at the same temperature, a much more efficient process than with MEA, which requires different temperatures for each step.
Despite its promising results, BEATA has a few challenges to overcome. Poderytė noted that while they see immense potential, there are "a lot of things to do and optimise" before it can be scaled up for industrial implementation and widespread use.
Another scientific challenge is that BAETA can react with itself and form oligomers, a process that can be avoided by ensuring a small amount of CO2 remains to stabilise the material.
Nevertheless, the research paper is a significant first step, and the team is confident in BAETA's potential for real-world application. As Poderytė said, "we for sure see the potential for it to be scaled up and implemented on a larger scale [...] As a team, we are constantly working on this and will try to bring this technology to the real world."
