Optimization of Ti/Ta2O5–SnO2 electrodes and reaction parameters for electrocatalytic oxidation of methylene blue

Among existing water treatment methods for organic-containing wastewaters, advanced oxidation process, particularly electrocatalytic oxidation, is a technique allowing to reach high degradation and mineralization efficiencies. Electrodes tested for use in electrocatalytic oxidation processes contain either expensive or platinum/group metals such as Pt-, Ru-, Ir-, Pd-, or boron-doped diamond and Sb and Pb compounds which are toxic for the environment. Thereby, there is a need for environmentally friendly and less expensive electrodes. The objectives of this research were to optimize annealing temperature of Ti/Ta2O5–SnO2 electrodes, establish the working media for organic compound oxidation processes as well as check degradation, mineralization and current efficiencies for methylene blue dye oxidation. Decolorisation efficiency of 95 % was achieved in 2 h at pH = 6.5. Neutral media showed also higher efficiency towards COD decrease which was equal to 85 % after 2 h of electrolysis. The lowest energy consumption of 7.7 kWh m−3 required for 100 % decolorisation was observed for the electrodes annealed at 550 °C at pH = 2. The highest current efficiency of 10.1 % attributed to 80 % of COD reduction was obtained for the electrode annealed at 550 °C at pH = 6.5. The optimization data allow further extrapolating of electrocatalytic oxidation process on Ti/Ta2O5–SnO2 electrodes to pilot scale.