Dip coating deposition of manganese oxide nanoparticles on graphite by sol gel technique for the indirect electrochemical oxidation of methyl orange dye: Parameter’s optimization using box-behnken design

Abstract

Textile industries produce large quantity of toxic effluents, very loaded and hardly biodegradable. In this work, MnO2 was synthetized by sol-gel method and coated on graphite rods which were obtained from used batteries and tested as electrodes for the degradation of anionic dye. Physical and chemicals characteristics of the material were determined by Fourier transform infrared and X-ray diffraction spectroscopies. The electrochemical properties of the elaborated material were carried out using linear sweep voltammetry and electrochemical impedance spectroscopy. During this study, experiments were carried out an electrochemical cell where C/MnO2 electrode was employed as cathode and anode. Box-Behnken design was used to design the experiments and find the optimal conditions for the degradation of Methyl Orange (MO) synthetic solution. The results also show that indirect anodic oxidation of MO using sodium chloride as supporting electrolyte was effective for MO degradation. However, the optimum conditions were 25 ​mg/L of initial dye concentration, 5 ​g/L of NaCl concentration, 5.6 ​h of electrolysis time, and 108 ​mA/cm2 of current density, where 77.0% degradation would be achieved from proposed model. According to these results, indirect anodic oxidation using manganese dioxide electrode in an electrochemical cell is efficient in the degradation of MO synthetic solutions.