Efficient Microwave‐Assisted Glycolysis of PET Fiber Waste: Optimization, Products Analysis, and BHET Recovery for Sustainable Recycling

Abstract In this study, the glycolysis of poly(ethylene terephthalate) (PET) fiber waste was conducted using excess ethylene glycol (EG) as the glycolysis agent and manganese acetate (Mn(Ac) 2 ) as the catalyst under microwave irradiation. Various parameters, such as reaction time, reaction temperature, PET:EG molar ratio, and the weight ratio of Mn(Ac) 2 to PET, were studied to enhance the degree of PET conversion. The experimental results showed that the reaction time was significantly decreased under microwave irradiation as compared with conventional heating. The purpose of this study was to identify the oligomers of PET as glycolysis products and to separate them, with the main goal being the isolation of monomer bis(hydroxyethyl terephthalate) (BHET). For this reason, the glycolysis products were analyzed and identified by Fourier transform infrared spectroscopy (FTIR) and Differential scanning calorimetry (DSC). Finally, at the optimal glycolysis temperature, the yield of BHET was calculated as a function of time. BHET isolation is particularly important for industries reliant on PET, such as packaging, textiles, and beverage containers, where recycled PET can be reintroduced as a sustainable alternative, promoting the principles of a circular economy and mitigating the environmental impact.