Removal of triazole fungicides of 1H-1,2,4-triazole from pesticide tailwater by electrochemical oxidation using meso-flower PbO2 layer electrode

Abstract

In this work, a novel Ti/TiO2-NTA/meso-flower PbO2 electrode (TMF-PbO2) was developed by anodic oxidation and modified oxygen bubble-template electrodeposition. Characterization of the electrode confirmed that the meso-flower layer exhibited a unique 3D and hierarchical structure with a rough morphology. N2 adsorption-desorption isotherms and cyclic voltammetry suggested that TMF-PbO2 possessed a 2.18 times larger specific surface area and at least a 1.46 times larger electroactive area than the electrode with a porous PbO2 layer. The investigation of the effect of the operation parameters indicated that the optimal conditions were a pH value of 3, supporting electrolyte concentration of 10.0 g L−1 and current density of 25 mA cm−2. The electrochemical degradation of 1H-1,2,4-triazole (Tz) by TMF-PbO2 was studied by HPLC and LC‒MS with the assistance of quantum chemical calculations. The TMF-PbO2 achieved 100% removal of Tz and 70.4% removal of COD on the advanced treatment of actual pesticide tailwater with an energy consumption of 29.40 kWh kg−1 COD. The EC50,48 h value and BOD5/COD ratio of the treated wastewater were 70.6±5.9% and 0.64, respectively, indicating significantly low toxicity and high biodegradability. Cyclic testing also suggested that TMF-PbO2 was stable during application. The excellent performance of TMF-PbO2 in this study indicated that this kind of electrode is highly applicable for the treatment of pesticide tailwater.