Scientists create hydrogen-based way to recycle plastic bottles

© Somnuek Saelim

Plastic bottles take up to 450 years to biodegrade naturally, so recycling them quickly is crucial for the environment – Northwestern University chemists may have a new strategy

Plastic pollution is one of the leading problems twenty-first century society is facing. Nearly 300 million tonnes of plastic waste continues to be produced every year, and around 91% of all plastic produced is not currently being recycled.

New techniques to recycle and reduce the environmental impact of plastic waste are continuously being discovered and explored, with Chemists from Northwestern University producing promising results.

The team at Northwester have demonstrated that a new material, referred to as a metal-organic framework (MOF), can function as a stable catalyst for breaking down polyester-based plastic into a chemical used in manufacturing – known as terephthalic acid.

According to the team this new method will require nothing more than the plastic debris, hydrogen and the MOF catalyst.

“We can do a lot better than starting from scratch when making plastic bottles,” said Omar Farha, corresponding author of the study. “Our process is much cleaner.”

“We can do a lot better than starting from scratch when making plastic bottles,” said Omar Farha, corresponding author of the study. “Our process is much cleaner.”

In addition to being easy to make, scalable and inexpensive, another advantage of UiO-66 is that the MOF’s organic linker, terephthalic acid (TA), is what you get when breaking down plastic.

“The MOF performed even better than we anticipated,” Farha said. “We found the catalyst to be very selective and robust. Neither the colour of the plastic bottle nor the different plastic the bottle caps were made from affected the efficiency of the catalyst. And the method doesn’t require organic solvents, which is a plus.”

Finding a new purpose for zirconium MOFs

Scientists have been using zirconium MOFs to degrade nerve agents for years. However, through this research the team began to wonder if these MOFs could also degrade plastic even though the reactions and mechanism are different.

That question led to the recent findings.

Farha further said: “The research helps address long-standing challenges associated with plastic waste and opens up new areas and applications for MOFs.”

Plastic pollution is an epidemic in climate terms

As of 2020 plastics consistently make up 80% of all marine debris studied, efforts into reducing it are at the forefront of climate activism.

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