Thermogravimetric study on pyrolysis kinetics of Chlorella pyrenoidosa and bloom-forming cyanobacteria

• The decomposition zone of CP and CB could be divided into three stages.
• Pyrolysis kinetics of CP and CB in stage II are investigated by SSGM and DAEM.
• MKAS method is used to study the SSGM kinetic of CP and CB.
• DAEM is calculated by discrete reactions with inverting Gaussian distribution.

The pyrolysis process of two microalgae, Chlorella pyrenoidosa (CP) and bloom-forming cyanobacteria (CB) was examined by thermo-gravimetry to investigate their thermal decomposition behavior under non-isothermal conditions. It has found that the pyrolysis of both microalgae consists of three stages and stage II is the major mass reduction stage with mass loss of 70.69% for CP and 64.43% for CB, respectively. The pyrolysis kinetics of both microalgae was further studied using single-step global model (SSGM) and distributed activation energy model (DAEM). The mean apparent activation energy of CP and CB in SSGM was calculated as 143.71 and 173.46 kJ/mol, respectively. However, SSGM was not suitable for modeling pyrolysis kinetic of both microalgae due to the mechanism change during conversion. The DAEM with 200 first-order reactions showed an excellent fit between simulated data and experimental results.