Scientists have come up with a new way of recycling plastic, returning the material to its “virgin” state.
The U.S. recycles hundreds of thousands of tons of plastic each year, which is still just a tiny fraction of the sum chucked into the landfill, according to the U.S. Environmental Protection Agency.
One of the problems with traditional methods of recycling is that it lowers the quality of the substance, so that the recycled plastic is of a lower grade than that of the original.
In practical terms, this means a plastic water bottle cannot be recycled and turned into another plastic water bottle over and over again. Rather, the recycled plastic can be used for products like piping and traffic cones that can be made from a lesser quality material.
The method developed by scientists, writing in ChemSusChem, is a form of chemical recycling as opposed to mechanical recycling, which is frequently used in everyday recycling processes.
The latter involves chipping the plastic into parts and melting it so that it can then be molded into something new. The actual material (or resin) doesn’t change, except to degrade in quality.
Chemical recycling, on the other hand, alters the physical state of the plastic, returning the material to its constituent parts (or building blocks) and thus a more purified (or “virgin”) form, by dissolving it in chemicals or breaking it down it with heat. It can then be returned to the industry and made into brand-new, high-quality plastic objects.
“Essentially, we are taking a repeating chain and cutting it up at regular intervals to give molecules that we can use again and again,” lead author Professor Matthew Jones, from the Centre for Sustainable & Circular Technologies at the U.K.’s University of Bath, told Newsweek.
“We can use the material for its intended use and then more easily recycle it.”
“Our method of chemical recycling could allow carbon to be recycled indefinitely,” Paul McKeown from the University of Bath in the U.K. said in a statement.
This could help create a “circular economy,” removing the need to “dig up” more fossil fuel from the ground to create new plastic or release it into the air as greenhouse gas, he added.
So far, the method has been tested with plant-based polylactic acid (PLA), a more environmentally-friendly type of plastic made using starch and crop waste (as opposed to fossil fuels) found in food packaging and disposable cutlery.
“PLA is being increasingly used as a sustainable alternative for single-use plastics,” said McKeown. “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.”
Jones, McKeown and colleagues have begun tests on PET—a plastic used for bottles and containers—employing a similar process. They are also working with scientists at the University of Birmingham in the U.K. to scale up the process so that it can be used on a more industrial scale, as opposed to the much smaller scale discussed in the paper.
When it comes to scaling up, there are two main challenges, Jones told Newsweek.
“One is the stability of our catalysts, which do all the work,” he said. “The other is designing the reactor, defining reaction parameters and deciding how long the process needs to be to get the optimum results.”
“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 problem of plastic recycling is unlikely to be solved by one solution due to the diverse range of materials available,” Jones told Newsweek. “However, for PLA there is good reason for chemical recycling and we hope our work inspires further work into this recycling method.”
The article has been updated to include comments from Professor Matthew Jones.