Scale-up upcycling of waste polyethylene terephthalate plastics to biodegradable polyglycolic acid plastics
Yuxiang Wang, Fulai Liu, Jiu Chen, Edmund C. M. Tse, Rui Shi, Yong Chen
Abstract
Electrochemical upcycling of waste polyethylene terephthalate (PET) into biodegradable polyglycolic acid (PGA) is a promising solution to relieve plastic pollution. However, both the low current density and tedious separation process for target glycolic acid (GA) products in a flow electrolysis have hindered industrial-scale applications. Here, we show an interfacial acid-base microenvironment regulation strategy for the efficient oxidation of PET-derived ethylene glycol (EG) into GA using Pd-CoCr2O4 catalysts. Specifically, only a cell voltage of 1.25 V is needed to deliver a current density of ca. 290 mA cm–2. Moreover, a green separation method is developed to obtain high-purity GA (99%). 20 kg of waste PET is employed for the pilot plant test (stack electrolyzer: 324 cm2 × 5), which exhibits 93.0% GA selectivity at 280 mA cm–2 (current: 90.72 A) with a yield rate of 0.32 kg h–1. After polymerization, PGA yield can reach up to 87%, demonstrating the potential of this technique for large-scale PGA production from waste PET. Electrochemical upcycling of waste polyethylene terephthalate (PET) is hindered by low current density and challenging glycolic acid separation. By constructing a Lewis acid substrate and employing a cost-effective purification strategy, the authors achieve a scale-up upcycling of waste PET.