Enhanced photodegradation of acid orange 61 by the novel hetero-junction CoFe2O4/AgCl

Abstract The objective of this study is to enhance the elimination of the textile dye Acid Orange (AO61) using the novel hetero-junction (CoFe2O4/AgCl), which was synthesized by the nitrate route at a different mass ratio. Before starting the photodegradation study, it is important to characterize the semiconductor. For that, the phase of the nanoparticles was identified by X-ray diffraction (XRD), and the morphology was investigated by scanning electron micrograph (SEM-EDS). The optical proprieties were analyzed using UV-VIS diffusion reflectance spectroscopy (DRS), an optical bandgap of 1.46 eV was found. For the electrochemical characterization, it was applied to determine the type of semiconductor as well as establish the energy diagram, a flat band of 0.3 VSCE corresponded to an p-type semiconductor has been determined. For the photodegradation of the orange acid dye, some operating parameters such as the mass ratio of CoFe2O4/AgCl, the catalyst dose, the pH of the solution and initial AO61 concentration were optimized. 25%/75% mass ratio of CoFe2O4/AgCl, catalyst dose of 1.25 g/L, pH ∼6 and 10 mg/L initial concentration were found as optimal conditions for the degradation performance under visible light with an efficiency of 98% within only 90 min. Different models were used to model the AO61 photodegradation, the kinetics were found in compliance with Hinshelwood Langmuir. Also, the photodegradation was tested under different sources of irradiation, a complete photodegradation was obtained for high concentration OA61 solution (50 mg/L) under solar irradiation within 90 min, which is much faster compared to other irradiation sources. In the final step, the mechanism of the AO61 photodegradation was studied and O2•- was found to be the main active radicals in the photocatalytic process.