Co-Pyrolysis of Large-Scale Agricultural Waste as a Mixture of Digestate and Plant Residues: Thermogravimetric Decomposition, Kinetic and Thermodynamic Study, Characterization of Pyrolysis Products

Abstract

With the continuous increase in agricultural waste, its proper management has become a significant environmental and resource management challenge. This study analyzed the co-pyrolysis of digestate (D) from chicken manure biogas residues and sunflower husks (SH). The weight loss, kinetics during decomposition, and thermodynamic parameters of thermochemical conversion were characterized using a synchronous thermal analyzer. The experiments were conducted at heating rates of 5, 10, 20, and 30 °C/min. The average activation energies for the pyrolysis of D90&SH10, D50&SH50, and D10&SH90 mixtures were obtained using the Kissinger-Akahira-Sunose method and were 274.95 kJ/mol, 239.37 kJ/mol, and 245.09 kJ/mol, respectively. The average activation energies for the pyrolysis of D90&SH10, D50&SH50, and D10&SH90 mixtures were obtained using the Ozawa-Flynn-Wall method and were 367.32 kJ/mol, 321.23 kJ/mol, and 328.52 kJ/mol, respectively. The average activation energies for the pyrolysis of D90&SH10, D50&SH50, and D10&SH90 mixtures were obtained using the Friedman method and were 445.87 kJ/mol, 395.99 kJ/mol, and 358.29 kJ/mol, respectively. The results of thermodynamic analysis confirm favorable conditions for shifting co-pyrolysis reactions towards the formation of stable products; therefore, the process can be carried out in an energy-efficient method. The material balance of thermochemical conversion indicates the potential for producing solid and liquid materials. The results of this study provide valuable information on co-pyrolysis, which contributes to its implementation as an efficient and environmentally friendly waste management strategy.