Microalgae decomposition in CO2 atmospheres by thermogravimetric analysis

Abstract

In this study, the effect of highly purified CO2 atmospheres on the thermal degradation processes of Chlorella vulgaris (a genus of unicellular green microalgae) was investigated by a thermogravimetric analysis (TGA) at the heating rate of 10 °C·min-1 from room temperature to 1000°C. The results indicated that the decomposition process of C. vulgaris in CO2 atmosphere could be divided into four stages and two main discrete decomposition stages were observed. In addition, the kinetics of C. vulgaris in CO2 atmosphere could be described by the pseudo multi-component overall model (PMOM). With the PMOM, the C. vulgaris considered as three pseudo components could be individually decomposed over a specify temperature range. The kinetic parameters, which calculated by Coats–Redfern method, showed that in CO2 atmosphere, the apparent activation energy (E) of C. vulgaris was in the between 9.863 and 309.381 kJmol-1 and the reaction order (n) was varied from 1.1 to 7, while the pre-exponential factor (A) was from 2.361 to 6.520×1017min-1.