Closed-Loop Recycling of Waste Colored Polyester Fabrics via Zerovalent Iron-Mediated Decolorization of BHET

Closed-loop recycling of waste colored poly(ethylene terephthalate) (PET) fabrics remains challenging due to the lack of an efficient decolorization method for bis(2-hydroxyethyl) terephthalate (BHET), which serves as the key intermediate in chemical recycling. In this study, an efficient zerovalent iron (ZVI)-mediated decolorization strategy was developed, in which ZVI acted as both the reducing and decolorizing agent. The decolorized BHET exhibited chromaticity parameters and color differences comparable to those of commercial BHET, with a decolorization efficiency exceeding 97%. Furthermore, the decolorized BHET was successfully repolymerized into PET and subsequently processed into filaments via melt spinning. The recycled PET exhibited a number-average molecular molar mass (Mn) of approximately 24,000 g·mol–1, along with thermal and tensile properties similar to those of commercial PET. Although slight yellowing was observed, the overall tensile performance of the recycled PET filaments remained comparable to that of virgin PET filaments, confirming the technical feasibility and potential for high-quality closed-loop recycling of colored polyester waste via this ZVI-mediated approach.