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Recycling polyesters, polycarbonates and more — at room temperature

| By Mary Page Bailey

A new catalytic recycling method that avoids harsh processing conditions could widely expand the recyclability of a broad range of plastics, including polycarbonates, polyesters and mixed-waste feeds. Researchers from the Center for Sustainable and Circular Technologies (CSCT; at the University of Bath ( reported that the process, which employs a zinc-based catalyst and methanol, could fully break down poly-bisphenol A carbonate (BPA-PC) beads into bisphenol A (BPA) and dimethyl carbonate (DMC) in just 20 min at room temperature. By efficiently breaking down BPA-PC, the catalyst not only handles a difficult-to-recycle waste stream, but it also prevents BPA, a harmful pollutant, from leaching into the environment.

This is said to be the first instance of metal-mediated BPC-PC methanolysis showing high activity at room temperature. In addition to methanolysis, the team investigated several chemical strategies, such as alcoholysis, glycolysis and aminolysis, to maximize the range of attainable products from different waste streams using the new catalyst. The catalyst can also break down other plastic materials, including polylactic acid (PLA), polyester amides (PEAs) and polyethylene terephthalate (PET). Traditional recycling technologies for these materials include energy-intensive processes like pyrolysis or hydrosilylation, so the ability to rapidly recycle them into their chemical constituents at ambient conditions brings many economic and sustainability benefits. The team has demonstrated the technology at laboratory scale, and work is ongoing to scale up the reaction volume.