Modified W, Ti-doped IrO2 anode for efficient organic contaminant oxidation in livestock wastewater

The treatment of livestock wastewater is a major environmental challenge due to the presence of antibiotics from animal excreta, which may pass through conventional biological oxidation treatment and pose a threat to public health. Electro-oxidation method presents an opportunity to remove antibiotics in the livestock wastewater at the source of generation, and titanium-based IrO2 anode has been shown to have excellent electro-catalytic activity and stability. However, the soaring price of iridium limits the practical application. In this work, we showed that W, Ti-doped IrO2 anodes largely preserved the electro-catalytic activity while reducing the cost of electrode fabrication. The prepared Ti/Sb-SnO2/(Ir0.6W0.2Ti0.2)Ox anode was shown to achieve 94 % conversion of sulfadiazine in 1 min and 100 % conversion in 15 min. Additionally, complete removal of chemical oxygen demand (COD0 = 700–800 mg/L) was achieved in 1–3 h of electrolysis at 40 mA/cm2. Chlorine-mediated oxidation was demonstrated to be the main mechanism for organic contaminant degradation. The COD removal during galvanostatic electrolysis exhibited zero-order kinetics, indicating that the reaction rate was controlled by the heterogeneous reaction at the anode surface. In the stability test, >95 % COD removal was maintained after 5 cycles of electro-oxidation experiments. The accelerated life of the anode was tested to be 352 h (1000 mA/cm2, 1 M H2SO4 electrolyte, 60 °C).