Application of central composite design for electrochemical oxidation of reactive dye on Ti/MWCNT electrode

In the present study, degradation of Reactive Orange 7 dye was investigated using a new designed titanium electrode, in which a plate of Ti was coated with multi-walled carbon nanotubes (Ti/MWCNT) via electrophoretic deposition technique. A series of characterizations including field scanning electron microscopy, X-ray diffraction, cyclic voltammetry, scanning electrochemical impedance spectroscopy and chronoamperometric analysis were performed to investigate MWCNT impact on the microstructure and electrochemical properties of Ti electrode. Furthermore, the effect of main operating parameters as independent variables (current density, electrolyte concentration, initial pH, and electrolysis time) on color removal efficiency as response variable were investigated and optimized by central composite design under response surface methodology. The maximum color removal efficiency of 89.1% and chemical oxygen demand removal efficiency of 55% were obtained, under the optimum condition. These results indicate that the presence of MWCNT on the Ti substrate noticeably promoted the electrochemical activity and the electrodes’ property for treatment of dye in aqueous solution.