Electrochemical degradation of azo dye methyl orange by anodic oxidation on Ti4O7 electrodes

Magnéli-phase Ti4O7 has been used in a diverse range of electrochemical applications due to its high electrical conductivity and great corrosion resistance. However, there are relatively few researches on the application of water treatment. In this paper, high density Ti4O7 ceramic electrode was successfully fabricated by the spark plasma sintering (SPS) and used as the anode for the electrochemical degradation of azo dye methyl orange. The phase, morphology and electrochemical properties of Ti4O7 electrode were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and cyclic voltammetry (CV), respectively. The experimental results revealed that the dye degradation was achieved by indirect electrochemical oxidation, mediated by electrogenerated ·OH radicals and active chlorine. Both of the slot voltage and supporting electrolyte concentration had positive effects on color removal of methyl orange whereas the decolorization rate decreased with the increasing initial concentration. The complete removal of color was achieved within a short period of electrolysis for almost all the experiments, and 98.1% of chemical oxygen demand (COD) was removed after 6 h electrolysis under the optimum conditions. This study would provide important significance for achieving efficient and sustainable electrochemical wastewater treatment using Ti4O7 electrode material.