The exploration of pyrolysis characteristics, kinetics and products of cotton via TG, FTIR, GC/MS and shuffled complex evolution

Cotton is one of the most important crops in the world and widely applied in many aspects. However, the fire safety of cotton should be paid attention to for its characteristics of porosity, low ignition point and fast combustion speed. Thermogravimetry-Fourier transform infrared spectroscopy-gas chromatography-mass spectrometry (TG-FTIR-GC/MS) is selected to explore pyrolysis characteristics of cotton. The DTG curves at different heating rates show a single peak with high and narrow shape, indicating that pyrolysis process mainly occurs in a narrow temperature range. The mean value of activation energy is 190.22 kJ mol⁻¹, 190.37 kJ mol⁻¹, 196.96 kJ mol⁻¹ by Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO) and Vyazovkin methods, respectively. The F2 reaction model is responsible for the pyrolysis process, and the mechanism function expression is G(α) = − 1[1 − (1 − α)⁻¹] by Coats-Redfern (CR) method. The optimized DTG curve by the shuffled complex evolution (SCE) method is consistent with experimental data. The main intermediate function groups detected by FTIR are C=O at 1750 cm⁻¹ and 2303 cm⁻¹, C–O at 2183 cm⁻¹, O–H at 3574 cm⁻¹, C–H at 2919 cm⁻¹, and the corresponding products are ketones, aldehydes and acids, CO₂, acids, gas H₂O and ketones, aldehydes and hydrocarbon. Seven kinds of gas products including 1H-imidazole-2-methanol, 1-acetoxy-p-menth-3-one, Z-11-pentadecena, 1,6-anhydro-β-D-glucopyranose, Nê-nitro-L-arginine, 7-hexadecyn-1-ol, 3-cyclopentene-1-acetaldehyde were detected in the GC/MS experiment.