Non-isothermal pyrolysis characteristics of giant reed (Arundo donax L.) using thermogravimetric analysis

A constructed wetland plant waste, Arundo donax L. (AD), was pyrolyzed from room temperature to 1000 °C under a dynamic high-purity nitrogen atmosphere at different heating rates. Results show that three stages occur during thermal degradation of AD. Mass loss rates associated with lignocellulose degradation were not affected by heating rates. Physical and chemical characterization of ADs pyrolyzed under different temperatures indicated that simultaneous pyrolysis occurred during the lignocellulose devolatilization process. The non-isothermal method indicated that the pyrolysis reaction should conform to a single-step reaction model with average E (activation energy) of 163 kJ mol−1, calculated by partial least squares linear regression. The most probable mechanism of thermal degradation of AD, determined by the Malek method with the calculated E as the initial value, is described with the random nucleation and later growth (Johnson–Mehl–Avrami (J–M–A) model). It can be written as f(α)=0.28(1−α)[−ln(1−α)]−2.57. Finally, E = 163.44 ± 3.50 kJ mol−1, the reaction order n = 0.28 ± 0.031, and the decimal logaritm of pre-exponential factor lg(A) = 13.13 ± 0.096 lg(s−1) were estimated.