Thermogravimetric analysis of textile waste: kinetic parameters and pyrolytic decomposition mechanisms

Abstract

Thermogravimetric analysis (TGA) is a powerful technique to elucidate the thermal decomposition behavior of textile materials, a critical step in designing efficient pyrolysis processes. In this study, new insights into the kinetic behavior and activation energies of various textile fibers, pure cotton, pure polyester, and cotton/polyester blends, using model-free kinetic methods (Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Friedman (FR)) and the Coast-Redfern (CR) method were provided. Thermogravimetric analysis (TGA) was performed at multiple heating rates (5, 10, 15, and 20 °C/min) under an N2 atmosphere to simulate pyrolysis conditions. Results revealed a clear relationship between fiber composition and decomposition behavior. Therefore, while pure cotton decomposes at 371 °C and pure polyester at 431 °C, blended fibers exhibit two distinct decomposition steps, a feature not previously reported in detail. The model-free methods indicated that the activation energy (Ea) increases with conversion (α), highlighting the complex multi-step decomposition of these fibers. For example, in pure cotton, Ea increases from 96.9 kJ/mol (α = 0.1) to 195.6 kJ/mol (α = 0.9), indicating a close dependence on the stages of decomposition. Furthermore, the CR method revealed that the most appropriate reaction models differ by fiber type, identifying the nucleation (F1) model as one of the most suitable, offering a predictive tool for optimizing pyrolysis conditions in industrial textile waste management.