Comprehensive investigation of activator influence on pyrolysis kinetics, thermodynamics, and product characteristics in one-step activated carbon preparation from spirulina

Abstract

The thermodynamics and kinetics effects of activators on the simultaneous activation pyrolysis of microalgae remain unclear. This study addresses this gap by investigating the effects of activators (KOH, KHCO₃, CH₃COOK, K₂CO₃) on Spirulina platensis (SP) pyrolysis using thermogravimetric-Fourier transform infrared spectrometer (TG-FTIR) and isoconversion methods. The results showed that all activators reduced the initial decomposition temperature of SP, leading to the earlier release of volatile pyrolysis products. Kinetics analysis further revealed that the addition of activators lowered the apparent activation energy (E_α) in the initial pyrolysis stage of SP. However, as the devolatilization process transitioned to the charring stage, the E_α gradually increased, surpassing that of SP pyrolyzed alone. Thermodynamic analysis indicated that the carbonization process of microalgae in the presence of activators required higher energy absorption. These findings reveal the mechanisms of activators in microalgae pyrolysis and provide insights into biochar production.