A new and simple method for upcycling plastic waste at room temperature has been developed by a team of British researchers.
The researchers at the University of Bath hope the new process will help recycling become less energy intensive, and thus more economically viable.
While recycling rates are growing across Europe, traditional methods remain limited because the harsh remelting conditions reduce the quality of the material each time they’re recycled.
But this new rapid chemical recycling process for polycarbonates can be completed in 20 minutes at room temperature.
Using a zinc-based catalyst and methanol, they were able to completely break down commercial poly(bisphenol A carbonate) (BPA-PC) beads that make up a widely-used class of thermoplastics commonly utilized in construction and engineering.
The waste can then be converted into its chemical constituents, namely bisphenol A (BPA) and dimethyl carbonate (DMC), helping to preserve its quality for reuse over an infinite number of cycles.
Also important, BPA recovery prevents leakage of a potentially damaging environmental pollutant, whilst DMC is a valuable green solvent and building block for other industrial chemicals.
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Promisingly, the zinc catalyst is also tolerant to other commercial sources of BPA-PC (e.g. CD) and mixed plastic sources, increasing industrial relevance, whilst being amenable to other plastics, like poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET), at higher temperatures.
The team has also demonstrated a completely circular approach to producing several renewable plastic derived from waste PET bottles—poly(ester-amide)s (PEAs) and their terephthalamide monomers. These materials have excellent thermal properties and could potentially be used in biomedical applications, for example drug delivery and tissue engineering.
Lead researcher Professor Matthew Jones, at the University of Bath’s CSCT, said, “It’s really exciting to see the versatility of our catalysts in producing a wide range of value-added products from plastic waste.
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“It’s crucial we target such products, where possible, to help promote and accelerate the implementation of emerging sustainable technologies through economic incentives.”
First author of the paper, Jack Payne from the CSCT, said, “Whilst plastics will play a key role in achieving a low-carbon future, moving forward, it’s imperative we source plastics from renewable feedstocks, embed biodegradability/recyclability at the design phase and diversify existing waste management strategies.”
“Such future innovation should not be limited to emerging materials but encompass established products too.
“Our method creates new opportunities for polycarbonate recycling under mild conditions, helping to promote a circular economy approach and keep carbon in the loop indefinitely.”
Presently, the technology has only been demonstrated on a small scale, however, the team is now working on catalyst optimization and scaling up the process (300 mL) with collaborators at the University of Bath.
This research has been published in ChemSusChem.
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