Glycol Vapor-Assisted Swelling and Dye Stripping Coupled with Magnetic Adsorption: An Integrated Strategy for Recycling Waste Polyester Textiles and Dyes

Current polyester recycling faces persistent challenges in dye separation. Herein, an integrated, recyclable closed-loop strategy combining in situ dye removal with magnetic adsorptive separation was proposed. Ethylene glycol vapor swelling was exploited to strip disperse dyes from poly(ethylene terephthalate) (PET) fibers. A magnetic adsorbent (designated as MF-OTMS) with a core-shell-functional-layer structure was synthesized to selectively capture disperse dyes through the synergistic effects of hydrophobic interactions and van der Waals forces. Key influencing factors and cyclic regeneration were examined, and the adsorption mechanism was elucidated. The decolorization ratio of the PET fabric reached 95.9%. MF-OTMS removed 91.16% of Disperse Red 1, retaining an efficiency of 82.33% after five cycles. The adsorption conformed to the pseudo-first-order kinetic model and the Langmuir model, indicating a spontaneous, exothermic, and monolayer physisorption process. This integrated strategy enables the simultaneous recovery of polyester monomers and dyes, offering significant economic and practical value.