Fabrication and characterization of Fe₂O₃, Bi₂O₃and BiFeO₃and evaluation of their photo catalytic performances on degradation of methylene blue dye

This study reports the fabrication of Fe2O3, Bi2O3, and BiFeO3, characterization and evaluation of the photocatalytic performances for methylene blue dye degradation. The materials were synthesized by precipitation method and characterized by scanning electron microscopy, X-ray diffraction, energy dispersive X-rays analyses, and Fourier transform infrared analyses. The photocatalytic activities of Fe2O3, Bi2O3, and BiFeO3 were compared by performing degradation experiments with 50 mL of 100 mg/L methylene blue solution. The as-prepared BiFeO3 was found as 2.4 times and 1.7 times more effective than Fe2O3 and Bi2O3, with a 79, 47, and 57% catalytic activity, respectively. The degradation of methylene blue over the BiFeO3 catalyst was optimized in terms of pH, catalyst dosage, temperature, and methylene blue concentration. The Eley-Rideal mechanism was proposed to describe the reaction kinetics in terms of the first order and second order kinetics model. Activation energy E (kJ/mol), enthalpy ΔH (kJ/mol), entropy ΔS (J/mol) and free energy ΔG (kJ/mol) were calculated as 20.8, 18.2, 197.5 and -45.3 respectively. The negative value of free energy shows that photodegradation is favored in present conditions.