Thermal decomposition kinetics of guarana seed residue through thermogravimetric analysis under inert and oxidizing atmospheres.

This work aims to analyze the thermal decomposition kinetics of guarana seed residue applying inert and oxidizing atmospheres. Thermal decomposition experiments were carried out in a thermogravimetric analyser using heating rates of 5, 10 and 15 °C/min. Three thermal decomposition stages were identified: dehydration; pyrolysis/oxidative pyrolysis, and carbonization/combustion, respectively.

Combustion reaction kinetics of guarana seed residue applying isoconversional methods and consecutive reaction scheme.

This work aims the study of decomposition kinetics of guarana seed residue using thermogravimetric analyzer under synthetic air atmosphere applying heating rates of 5, 10, and 15°C/min, from room temperature to 900°C. Three thermal decomposition stages were identified: dehydration (25.1-160°C), oxidative pyrolysis (240-370°C), and combustion (350-650°C).

Immobilization of Paecilomyces variotii tannase and properties of the immobilized enzyme.

Tannase produced by Paecilomyces variotii was encapsulated in sodium alginate beads and used for the effective hydrolysis of tannic acid; the efficiency of hydrolysis was comparable to that of the free enzyme. The alginate beads retained 100% of their efficiency in the first three rounds of successive use and 60% in rounds 4 and 5. The response surface methodology showed that the best conditions to hydrolysis of tannic acid by immobilized tannase were: sodium alginate 5.