Combustion behavior and kinetics of low-lipid microalgae via thermogravimetric analysis

• Combustion of low-lipid microalgae C. pyrenoidosa and S. platensis were studied.
• Chemical functional groups present in two microalgae were investigated via FTIR.
• Apparent activation energies for combustion of the two microalgae were calculated.
• C. pyrenoidosa has a higher reactivity compared to S. platensis during combustion.

Thermogravimetric analysis and differential thermal analysis were employed to investigate combustion characteristics of two low-lipid microalgae, Chlorella pyrenoidosa (CP) and Spirulina platensis (SP) and iso-conversional Starink approach was used to calculate the kinetic parameters in the present study. The results showed that three stages of mass loss, including dehydration, devolatilization and char oxidation, were observed during combustion of both of two low-lipid microalgae. The whole weight loss of combustion of two microalgae was both shifted to higher temperature zones with increased heating rates from 10 to 40 K/min. In the 0.1–0.9 conversion range, the apparent activation energy of CP increased first from 51.96 to 79.53 kJ/mol, then decreased to 55.59 kJ/mol. Finally, it slightly increased to 67.27 kJ/mol. In the case of SP, the apparent activation energy gradually increased from 68.51 to 91.06 kJ/mol.