Efficient Chemical Upcycling of Waste Poly(ethylene terephthalate) Bottles through Hydrolysis Catalyzed by Terephthalic Acid

Polyethylene terephthalate (PET) depolymerization supports the sustainable use of resources by recovering the monomer pertaining to the circular economy. The recycling rate of PET waste is quite low; consequently, there is a need to create accessible and low-carbon-footprint depolymerization technologies to rely on this plastic waste in value-added applications. This study uses terephthalic acid (TPA) as a catalyst to hydrolyze waste PET into its monomer, TPA. During hydrolysis, TPA facilitates the selective cleavage of PET’s ester bonds, allowing for efficient breakdown and recycling of PET flakes. Optimized reaction conditions for the TPA-assisted hydrolysis achieve up to 99.9% PET conversion, a maximum TPA yield of 95.3%, and over 98% purity, matching commercial TPA standards. This work primarily focuses on conversion and the role of workup in improving product recovery and purity. The end quality of the TPA obtained was further confirmed by HPLC, and 1H NMR and 13C NMR for purity assessment found high-purity TPA. Additionally, this study emphasizes the importance of workup in enhancing both the recovery and purity of the final product.