Decomposition Characteristics and Kinetics of Microalgae in N2 and CO2 Atmospheres by a Thermogravimetry

The thermal degradation characteristics of microalgae were investigated in highly purified N2 and CO2 atmospheres by a thermogravimetric analysis (TGA) under different heating rates (10, 20, and 40°C/min). The results indicated that the total residual mass in CO2 atmosphere (16.86%) was less than in N2 atmosphere (23.12%); in addition, the kinetics of microalgae in N2 and CO2 atmospheres could be described by the pseudo bicomponent separated state model (PBSM) and pseudo-multi-component overall model (PMOM), respectively. The kinetic parameters calculated by Coats-Redfern method showed that, in CO2 atmosphere, the apparent activation energy ( ) of microalgae was between 9.863 and 309.381 kJ mol−1 and the reaction order ( ) was varied from 1.1 to 7. The kinetic parameters of the second stage in CO2 atmosphere were quite similar to those in N2 atmosphere.