Thermal degradation of food waste by TG-FTIR and Py-GC/MS: Pyrolysis behaviors, products, kinetic and thermodynamic analysis

Abstract

Abstract Thermal degradation of food waste has attracted widespread interest in recent years. The presented investigation focused on the thermal decomposition behavior, volatile release characteristics, and the pyrolytic product composition and distribution of two typical food waste components (pork and rice) via Thermogravimetric analyser coupled with Fourier Transform Infrared spectrometer and Pyrolyzer combined with a Gas Chromatograph and Mass Spectrometry. According to the pyrolysis experiments, two different pyrolysis stages occurred both in pork and rice, which were the volatilization of moisture and the main pyrolysis reaction. The gaseous products and typical functional groups of the released volatiles were detected by Infrared spectroscopy and mainly contained CO2, CO, small-molecule hydrocarbons, and oxygen-containing and nitrogen-containing functional groups. With the specific information from Pyrolyzer combined with a Gas Chromatograph and Mass Spectrometry, the pyrolytic products were classified into small-molecule gases, hydrocarbons, oxygenated compounds and nitrogen-containing compounds. Additionally, the methods of Friedman, Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose were applied to calculate kinetic parameters, which indicated that the activation energy values of pork were lower than those of rice. The values of enthalpy, Gibbs free energy, and entropy also revealed that the pyrolysis process of rice was more complicated than that of pork. The kinetic and thermodynamic results provided an important reference for future reactor design and the thermochemical treatment of mixed food waste.