Kinetic analysis of the pyrolysis process of microbiologically modified sunflower husks

The article presents a kinetic analysis of the pyrolysis process of raw sunflower husks and those subjected to microbiological modifications (using fungal and fungal-bacterial suspensions). The study was conducted using thermogravimetric analysis (TGA), which monitored the sample's mass change as a function of temperature. Two kinetic analysis methods were employed: a model-free method (Kissinger–Akahira–Sunose, KAS) and a model-based approach, assuming three independent reactions corresponding to the decomposition of hemicellulose, cellulose, and lignin. The results demonstrated that microbiological modifications reduced the decomposition temperature and increased mass loss, indicating enhanced biomass degradability. A particularly notable effect was the reduction in activation energy for cellulose and lignin, suggesting a weakening of the lignocellulosic structure by microorganisms. The fungal suspension had a stronger impact on cellulose, while the fungal-bacterial suspension more significantly affected lignin. The model-based kinetic analysis confirmed that biomass decomposition occurs through three independent reactions, each characterized by distinct kinetic parameters. Microbiological modifications altered the contribution of individual reactions to the overall decomposition, increasing the share of hemicellulose at the expense of cellulose. These findings suggest that microorganisms may depolymerize cellulose into hemicellulose, thereby facilitating its breakdown. The study confirms the effectiveness of microbiological treatment in enhancing the pyrolysis efficiency of sunflower husks, which may have implications for their industrial application as a renewable energy source.