Iron precipitation kinetics during microbial ferrous-ion oxidation

This study investigates the kinetics of ferric-ion precipitates, particularly potassium jarosite (K-jarosite), formed during microbial ferrous-ion oxidation in bioleaching. Experiments using a mesophilic bacterial culture at temperatures of 30, 35, and 40°C over 14 days revealed that ferric-ion precipitation began after 24 hours, with a maximum of 2.48 grams forming at 40°C. Characterization through XRD, SEM, FTIR, and TGA confirmed the presence and properties of K-jarosite. Kinetic analysis showed that precipitation follows first-order kinetics, with an activation energy of 117.2 kJ/mol, indicating an endothermic and non-spontaneous process. These findings offer insights into controlling jarosite accumulation to enhance bioleaching efficiency.