A breakthrough in chemical recycling

Close to 45% of plastic waste is recycled annually in the UK, and this number is increasing. However, the main issue with current plastic recycling methods is that you end product is a lower-quality plastic, with worse properties than the original. Because of this, the plastic drinks bottles cannot simply be recycled into new drink bottles over and over, but instead are used for other, lower-grade products, such as park benches, traffic cones, building materials and others.

Now, scientists from the Universities of Bath and Birmingham have developed a new way of chemical recycling—converting plastics back into constituent chemical molecules—so that they can be reused to make new plastics of the same quality as the original. The method also require lower temperatures and more environmentally-friendly catalysts than previously used methods.

“Most plastic is currently recycled using mechanical methods, where they are chipped into granules and melted down before being molded 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.”

Professor Matthew Jones, The Centre for Sustainable and Circular Technologies at the University of Bath.

The researchers recycled plant-based PLA, made from starch or crop waste instead of petrochemicals, and is used in “biodegradable” food packaging and disposable cutlery and cups. PLA isn’t currently being recycled, as it’s not yet widely used, but with growing awareness of plastic pollution, the demand from consumers for recyclable packaging is growing. A similar process was tested, for recycling PET, which is used for drink bottles.

“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 tons of waste in landfill and oceans. 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.”

Dr. Paul McKeown from the University of Bath, author of the paper

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

Reprinted from the University of Bath