Nonisothermal drying kinetics of biomass fuels by thermogravimetric analysis under oxidative and inert atmosphere

Abstract

In depth investigation of nonisothermal drying kinetic, the first stage of thermal decomposition was conducted using thermogravimetric analysis, to deepen the thermal processes’ knowledge. The studied biomass wastes were peach pits, marc, and stalk from the canning, jam, and wine industries, respectively. The experimental data have been obtained under oxidative and inert atmospheres at different heating rate (5, 10, and 15 K/min), to fit to different isoconversional models to describe drying behavior of agro-industrial wastes. These models were evaluated based on different statistical parameters. The best fitting for all experiments were showed by Jander’s model. It is assumed that the three-dimensional diffusion is the drying rate controlling step. The calculated activation energy values are between 20.31 and 48.41 kJ/mol for all agro-industrial wastes at different experimental conditions. Calculated kinetic parameters for the nonisothermal drying under nitrogen atmosphere are generally higher than those for this phenomenon under air atmosphere. Different physicochemical phenomena are produced, which cause this variation during the drying under different atmospheres. Heating rates have a slight effect on the activation energy since the kinetic rate of drying phenomenon is controlled by the physical transformation occurrence, which is dependent on temperature and it is not on mass dependent.