Highly Efficient and Complete Degradation Strategy of Polyethylene Terephthalate Fibers Using a Synergistic Deep Eutectic Solvent/Alkali System Under Mild Conditions

Polyethylene terephthalate (PET) textile waste, which is resistant to degradation, contributes significantly to environmental pollution. Currently, traditional methods, such as high-temperature and high-pressure treatments, microwave heating, etc. exhibit low initial degradation rates for polyester fibers while also facing challenges such as high energy consumption, complex degradation products, and difficulties in subsequent reuse. Thus, research on efficient recycling and sustainable development of PET waste has become imperative. Here, we report a novel method to degrade PET fibers completely at low temperatures within 1 h. A synergistic hydrolysis system consisting of a deep eutectic solvent (ChCl–EG DES) composed of choline chloride and ethylene glycol, along with sodium hydroxide (NaOH) was used to facilitate the highly efficient and complete degradation of polyester fibers under mild conditions. The degradation process can be conducted at temperature below 100 °C, achieving a degradation rate of up to 100%, with the degradation product being sodium terephthalate, which exhibits a high purity of 99.85% and can be directly reused as a raw material without complex treatments and purification steps. The degradation kinetic of polyester fibers fits first-order reaction, with an activation energy of 108.59 kJ/mol. Overall, this study provides a green, low-cost, and energy-saving strategy with practical application value for efficient degradation and recycling of polyester fibers.