Scientists reveal new way of recycling plant-based plastics

A group of scientists from the Universities of Bath and Birmingham have developed a new chemical method of recycling plant-based plastics.

Current recycling methods result in lower quality plastic that must be used for lower grade products such as water pipes and traffic cones instead of drink bottles.

The new method, published in ChemSusChem, converts plastics back into their constituent chemical molecules potentially allowing them to be recycled repeatedly into new plastics without losing quality.  

One of the authors, Professor Matthew Jones from the University of Bath, said: “Most plastic is currently recycled using mechanical methods, where they are chipped into granules and melted down before being moulded into something new.

“The problem is, melting plastic changes its properties, and reduces the quality, which limits the range of products in which it can be used.

“Our method of chemical recycling overcomes this problem by breaking down plastic polymers into their chemical building blocks, so they can be used all over again to make virgin plastic without losing any properties.”

The team’s method uses lower temperatures and more environmentally friendly catalysts than previous methods.

It has been trialled on plant-based PLA, which is made from starch or crop waste instead of petrochemicals and is used in biodegradable food packaging.

“PLA is being increasingly used as a sustainable alternative for single-use plastics. Whilst it’s biodegradable under industrial conditions, it doesn’t biodegrade with home composting, and isn’t currently recycled, so at the moment it commonly ends up contributing to the tonnes of plastic waste in landfill and oceans,” said Dr Paul McKeown from the University of Bath.

McKeown added: “There is no single solution to the problem of plastic waste – the approach has to be a combination of reducing, reusing and recycling. Our method of chemical recycling could allow carbon to be recycled indefinitely – creating a circular economy rather than digging more up from the ground in the form of fossil fuels or releasing it into the atmosphere as a greenhouse gas.”

The technology has only been demonstrated on a small scale, however collaborators at the University of Birmingham are now working to scale up the system to produce larger quantities of starting chemicals.

The team has also started trialling a similar process for recycling PET.