Mixtures of plastics, usually a headache to recycle, have been broken down into useful, smaller chemical ingredients in a two-step process, reported in Science on 13 October1.A team led by Gregg Beckham, a chemical engineer at the US National Renewable Energy Laboratory (NREL) in Golden, Colorado, have developed a two-step process that uses chemistry and then biology to break down a mix of the most common plastics that make it into recycling plants: high-density polyethylene (HDPE), a soft plastic often found in food packaging; polystyrene, which includes styrofoam; and polyethylene terephthalate (PET), a strong, lightweight plastic used to make drink bottles.“Only a few works have reported chemical recycling of plastic mixtures before,” says Ning Yan, a chemist at the National University of Singapore and one of the few researchers to have developed a system capable of that2.Two-step processThe team first used a catalysed oxygenation reaction, with a cobalt or manganese-based catalyst, to break down the tough polymer chains into oxygen-containing organic-acid molecules.“There’s a lot of in-house knowledge built in, and if one or more of these companies would choose to explore this, I think they could offer a lot of technical know-how,” Stahl says."