Study on preparation of a novel needle coke heterogeneous electro-Fenton cathode for coking wastewater treatment

Abstract

Coking wastewater is a major challenge in wastewater treatment because of its complex composition, high pollutant concentrations, and poor biodegradability. In this study, a novel electro-Fenton cathode was prepared from needle coke loaded with ferrous ions (Fe/NC/Ti) for use in a heterogeneous electro-Fenton system for coking wastewater treatment. The optimum preparation conditions of the electrode and the main factors affecting the treatment of coking wastewater were investigated. An effective method to reduce the energy consumption of the electro-Fenton system was sought by constructing variable current systems, and scale-up experiments were performed. When the catalyst-to-binder ratio was 3:1, Fe2+ loading was 2.5 %, and the calcination temperature was 400 °C, the Fe/NC/Ti cathode had the best catalytic effect. The chemical oxygen demand (COD) removal rate of the coking wastewater reached 97.7 %, and UV254 decreased from 0.163 to 0.037 under optimal conditions. The water was clarified and made transparent after the reaction. A series of characterizations confirmed that the Fe/NC/Ti cathode had good stability and electrochemical performance, and the electro-Fenton system constructed using the cathode degraded aromatic compounds in coking wastewater, such as phenols and cyclic macromolecular organic compounds, to small molecules and even caused full mineralization. The results of the scale-up experiment showed that the system had low energy consumption while maintaining high COD removal efficiency. Therefore, the Fe/NC/Ti cathode could be used as a potential solution to address the limitations of the traditional electro-Fenton process for coking wastewater degradation.