Kinetic study of horse manure through thermogravimetric analysis

Abstract

Horse manure contains potential source of bioenergy that can be pyrolysed to obtain bio-oil and synthesis gas. In the present work, horse manure samples collected from the horse stable in Universiti Teknologi Malaysia were analysed through thermogravimetric analysis (TGA) to determine the Arrhenius parameters and thermodynamics properties. TGA was conducted on the horse manure at heating rates of 1, 2, 5, 10 °C/min in a nitrogen-filled reactor. The TGA data was analysed by using three different model-free, non-isothermal methods, namely Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Kissinger methods. Result shows the temperature for highest conversion of horse manure is within the range of 290.2-329.6 K. The Kissinger method shows the overall average activation energy of 148.47 kJ/mol, whereas FWO and KAS methods show the activation energy at different conversional fractions throughout the process with the range of 176.2-293.6 kJ/mol and 175.6-300.1 kJ/mol. Thermodynamic properties including the pre-exponential factor, enthalpy change, free Gibbs energy and entropy of horse manure during pyrolysis were also determined.