【Frontiers in HaiChuan Chemical Technology】Progress achieved in research on recycling waste polyester plastics at Jiangnan University

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Recently, Dr. Cao Jingjing from Jiangnan University, in collaboration with German researchers, successfully developed a low-cost and earth-abundant \"unsaturated coordination-defect zinc oxide nanosheet catalyst\" that provides a new solution for the efficient and environmentally friendly recycling of waste polyester plastics under mild conditions. The relevant research findings were published in Nature Communications. 　　Polyester plastics are produced in large quantities each year, but traditional chemical recycling methods suffer from issues such as high energy consumption, equipment corrosion, and difficulties in wastewater treatment. In this study, the team designed zinc oxide catalysts with a special defect structure on their surface. They vividly compare it to a \"molecular scalpel,\" with the surface defect sites acting as highly active \"graspers\" that can preferentially adsorb and activate water and oxygen molecules, thereby precisely breaking the chemical bonds of polyesters in a near-neutral aqueous environment, without the need for organic solvents or strong bases. 　　Experiments show that in an air environment at 190°C, this catalytic system can completely depolymerize polyethylene terephthalate (PET) in just 6 hours, with a selectivity for the target product terephthalic acid exceeding 99%. Furthermore, this catalyst exhibits excellent \"substrate versatility\"; it can efficiently process both ordinary mineral water bottles and used textiles containing impurities such as dyes, maintaining a terephthalic acid recovery rate of over 98%. This technology is also applicable to the highly selective monomer recovery from other polyester wastes. In terms of environmental friendliness, the catalyst maintained stable activity after 5 consecutive cycles of use, and no leaching of harmful zinc ions was detected during the reaction, thereby avoiding secondary pollution. To date, the research team has completed laboratory-scale scaling up to 40 grams, successfully converting waste plastic into high-purity raw materials and reproducing recycled PET.