Kinetic study of regional agro-industrial wastes pyrolysis using non-isothermal TGA analysis

Abstract

Pyrolysis characteristics and kinetic study of six regional lignocellulosic wastes (sawdust, marcs, stalks, peach plum and olive pits) at different heating rates was investigated using thermogravimetric analysis. The pyrolysis could be divided into three stages, drying, active and passive pyrolysis. The specific location where the thermal degradation reaction are occurring is called active pyrolysis zone. The samples have the highest residual weight equal to 35-40% at 603 K, approximately during this stage. To describe the active pyrolysis behavior, the Coats Redfern and Sharp methods were used. The contraction geometry´s model describe this phenomenon, indicating that the degradation rate is controlled by the resulting reaction interface progress toward the center of the solid. The activation energy values for the active pyrolysis stage are between 38.96 and 68.99 kJ/mol for all studied agro-industrial wastes. This parameter increases with the heating rate. This variation can be due to the kinetic rate of active pyrolysis is controlled by the occurrence of physical transformation the temperature-dependent which is not mass dependent. The calculated values of pre-exponential factor were about 2.01 ∗ 107 and 2.51 ∗ 1010 s-1. These parameters indicate that the pyrolysis of the studied wastes similar to other lignocellulosic materials, proving the feasibility of their valorization by pyrolysis.