Sulfonamides removed from simulated livestock and poultry breeding wastewater using an in-situ electro-Fenton process powered by photovoltaic energy

Abstract

An in-situ electro-Fenton system with double anodes and Pd/CeO2 catalyst, which is powered by photovoltaic energy, is constructed. As the process only needs to replace the catalyst and iron anode regularly, and H2O2 and Fe2+ are in-situ generated and continuously added, it not only greatly reduces labor intensity and safety risks but also saves reagents and run cost. In this paper, the process is used to remove sulfadiazine (SDZ), one of the sulfonamides, from the simulated livestock and poultry breeding wastewater containing antibiotics. The results show that the features of Pd/CeO2 catalyst are successfully characterized by XRD, TEM and XPS. Under the conditions of only catalyst, only power, power and catalyst and electro-Fenton (EF), sulfadiazine removal efficiency for EF is the highest and 96.5% in 150 min. In addition, sulfadiazine removal follows a pseudo-first-order kinetic model. Current density of 15 mA/cm2, pH of 3, catalyst dosage of 0.1 g and current ratio of 0.15:0.02 is determined as the optimal conditions. Whether irradiation intensity is very weak or fluctuates broadly, sulfadiazine removal efficiency is all very high and more than 95% in 150 min. TOC results indicate that the mineralization extent of sulfadiazine is very high and HPLC results show that the adopted process is highly effective. Based on the UHPLC/MS results, seven intermediate products are detected and the removal mechanisms of sulfadiazine are proposed. The in-situ electro-Fenton process powered by photovoltaic energy is feasible.