Degradation of 2,4-dichlorophenol by anodic oxidation using Ti-based oxide electrodes

Ti-based oxide electrodes coated with IrO2,RuO2 and TiO2 (Ti/IrO2/RuO2/TiO2) prepared by a thermal oxidation process were employed to investigate:① the cyclic voltammetry characteristics of 2,4 dichlorophenol (DCP) in water solution; ② the influences of pH,anodic potential and reaction time on DCP degradation by the anodic oxidation process; ③ the influence of anodic oxidation on the bio-degradability of DCP solution. The results showed that the loading of oxides had a significant effect on the cyclic voltammetry curves. A higher pH was beneficial to the electrochemical oxidation of DCP while a lower pH tended to cause more DCP to volatize. At lower anodic potentials,DCP degradation was ascribed to the direct electrochemical oxidation and in this case,degradation was poor because of the lower current density. At higher anodic potential,DCP degradation was ascribed to indirect electrochemical oxidation. A DCP removal of 100% and a COD removal of higher than 50% were achieved at an anodic potential of 1.8 V with a reaction time of 360 min,but the power consumption was high. The results of COD reduction and the UV-visible spectra indicated that some organic intermediates were produced during the course of DCP degradation. Anodic oxidation using the Ti/ IrO2/RuO2/TiO2 electrode was able to enhance the bio-degradability of DCP solution,which suggests it is a promising alternative for the pretreatment or detoxification of wastewaters containing chlorophenols.