Combustion of pistachio shell: physicochemical characterization and evaluation of kinetic parameters.

The study of different renewable energy sources has been intensifying due to the current climate changes; therefore, the present work had the objective to characterize physicochemically the pistachio shell waste and evaluate kinetic parameters of its combustion. The pistachio shell was characterized through proximate analysis, ultimate analysis, SEM, and FTIR. The thermal and kinetic behaviors were evaluated by a thermogravimetric analyzer under oxidant atmosphere between room temperature and 1000 °C, in which the process was performed in three different heating rates (20, 30, and 40 °C min-1). The combustion of the pistachio shell presented two regions in the derivative thermogravimetric curves, where the first represents the devolatilization of volatile matter compounds and the second one is associated to the biochar oxidation. These zones were considered for the evaluation of the kinetic parameters E a , A, and f(α) by the modified method of Coats-Redfern, compensation effect, and master plot, respectively. The kinetic parameters for zone 1 were E a1 = 84.11 kJ mol-1, A 1 = 6.39 × 106 min-1, and f(α)1 = 3(1 - α)2/3, while for zone 2, the kinetic parameters were E a2 = 37.47 kJ mol-1, A 2 = 57.14 min-1, and f(α)2 = 2(1 - α)1/2.