Chemical Recycling of PET Polyester Textile Wastes Using Ag-Doped ZnO Nanoparticles: An Economical Solution for Circular Economy

Abstract

Polyethylene terephthalate (PET) is a nonbiodegradable and multi-functional plastic commodity that produces a significant amount of polyester (PES) textile waste. The management of PET solid waste is a global concern in many developing countries. Chemical recycling and material recovery from PES wastes can rebuild a circular economy in the textile sectors. The main objective of the present research is to enhance the chemical depolymerization of PES's textile wastes through microwave-induced catalytic aminolysis and glycolysis catalysed by Ag-doped ZnO nanoparticles. Catalysts are synthesised by the sol-gel method and characterised using X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), ultraviolet spectroscopy (UV-Vis), field emission scanning microscope (SEM-EDX), and transmission electron microscope (TEM). These parameters included the PET to catalyst ratio, microwave power, time, temperature, and catalyst recycling studies. The catalyst was discovered to be more stable and could be recycled up to six times without losing its activity. Microwave heating is typically faster than conventional heating techniques in terms of reaction time, PET conversion, product yield, and purity. In the aminolysis of PET, the effects of several factors on the conversion of PET and the yield of bis (2-hydroxy ethylene) terephthalamide (BHETA) and the glycolysis process to produce bis (2-hydroxy ethylene) terephthalate (BHET) were examined. The study's findings show that higher temperatures (180 °C) are beneficial for PES textile waste conversion and BHETA yield, which can reach nearly 95% and 94%, respectively. Finally, FT-IR, 1H NMR, and mass spectroscopy (MS) were used to characterise the depolymerized products. The study showed that 2 mol% Ag-doped ZnO showed better catalytic activity.