Closing the Loop on Polyester: A Green Approach to Chemical Recycling with Zn[L-Proline]2 Supported Kaolin Catalyst

Abstract

In present work, the depolymerization process utilizes kaolin-supported Zn[L-proline]2 (ZnP@K) as a recyclable Lewis acid catalyst, paving the way for the cost-effective production of recycled materials. The supported catalyst is characterized using FTIR, X-ray diffraction, SEM and BET analysis. The depolymerization of polyester textile waste, especially coloured threads, promoted by ZnP@K to yield more than 90% of monomers in pure form. In addition, irrespective of the colour of polyester threads, the process exhibited 100% conversion of polyester threads and obtained pure colourless monomers, bis(2-hydroxyethyl)terephthalate (BHET) and bis(2-hydroxyethyl)terephthalamide (BHETA). The monomers are assessed for their structure and purity using FTIR, mass and NMR spectral techniques. While comparing with ZnO nanoparticles, ZnP@K depolymerized the polyester wastes in terms of yield and purity and it proved efficient and sustainable for recycling textile polyester waste.