Investigation of Non-Isothermal Kinetics and Thermodynamic Parameters for the Pyrolysis of Different Date Palm Parts

Using the thermalgravimetric technique, we investigated the non-isothermal combustion kinetics of abundant and low-cost date palm wastes (leaflet, rachis, fibers, and their composite) as potential biomass energy sources. The kinetic and thermodynamic parameters were determined by Flynn-Wall-Ozawa (FWO), Kissinger-Akahila-Sunose (KAS), and Starink methods. Thermogravimetric analysis results showed a major peak for the degradation of volatiles between 127-138 degrees C with average percentage mass loss of 68.04 +/- 1.5, 65.57 +/- 0.6, 62.97 +/- 5.5, and 59.26 +/- 3.2, for rachis, composite, leaflet, and fibers, respectively. The FWO model showed the lowest activation energy, E-alpha, of 157 +/- 25.6, 158 +/- 25.7, 164 +/- 40.1, and 169 +/- 51.8 kJ mol(-1) for the composite, rachis, leaflet, and fibers, respectively. The positive enthalpy values confirmed an endothermic pyrolysis reaction. For all models, a minimal difference of 4.40, 5.57, 6.55, and 7.51 kJ mol(-1) between activation energy and enthalpy for rachis, fibers, composite, and leaflet ensued, respectively. The KAS model was best suited to describe chemical equilibrium with average Delta G values of 90.3 +/- 28.8, 99.3 +/- 34.9, 178.9 +/- 27.3, and 186.5 +/- 38.2 kJ mol(-1) for rachis, fibers, composite, and leaflet, respectively. The reaction mechanism by the Malek and Popescu methods was ((g(alpha)=[-ln(1-alpha)]14) across the conversion range of 0.1-0.9 for all heating rates. The high energy content and volatile matter combined with low energy barriers make date palm waste a potential candidate in a biorefinery.