Chemical recycling of polyester fabrics by alkaline hydrolysis using alcohols as cosolvents

This research reports a route for chemical recycling of polyester textile fibres as a promising solution to the accumulation of these textile wastes. The aim of the study was to investigate the effect of using alcoholic cosolvents (methanol, ethanol and isopropanol) on the alkaline hydrolysis of polyester textile fibres. Through this cosolvent assisted process, polyester chains break down under mild conditions into their monomers, terephthalic acid and ethylene glycol. Key parameters, including temperature, sodium hydroxide concentration, cosolvent/water ratio and reaction time, were evaluated to assess their influence on polyester conversion and terephthalic acid yield. Results were analysed using a kinetic model based on the shrinking core theory, providing insights into the mechanisms of cosolvent assisted hydrolysis. This model effectively described the kinetics for fractional conversion below 0.5. At high conversion, however, some deviations were observed due to the non-uniform degradation of the polyester fibres. The degraded polyester fibres were characterized by Scanning Electron Microscopy (SEM) and viscometry, while the TPA product was analysed by Nuclear Magnetic Resonance (NMR)