Efficient Recovery and Fast Hydrolysis of Polyethylene Terephthalate by Dihydrolevoglucosenone (Cyrene).

Abstract

Polyethylene terephthalate (PET) is a versatile, relatively low-cost thermoplastic polymer, but its nonbiodegradability and extensive use lead to significant accumulation and environmental risks. The main roadblocks of current plastic recycling technologies include low-quality recycled plastics and inefficient degradation under harsh conditions, which highlights the urgent need to develop efficient and sustainable recycling processes. Herein, for the first time, a strategy is developed using bio-based solvent dihydrolevoglucosenone (Cyrene) for efficient recycling of waste PET-to-polymer or monomer. In this study, Cyrene effectively dissolves PET at 165 °C within 20 min. Furthermore, PET dissolved in Cyrene and regenerated by ethanol as an antisolvent, exhibiting excellent chemical and thermal stability with minimal degradation. Cyrene also functions as a cosolvent for the alkaline hydrolysis of PET, resulting in ≈100% PET degradation to terephthalic acid (TPA) with a yield of 98.2% within 18 min at 80 °C. The presence of Cyrene enhances the interface compatibility between PET and solvent, while the hydroxyl groups in EG form hydrogen bonds with Cyrene, facilitating the interaction between PET and NaOH. Overall, this study contributes to the advancement of solvent-based recycling strategies for the cost-effective recovery of PET waste.