Preparation of a needle coke-based gas diffusion electro-Fenton cathode for coking wastewater treatment

Abstract

A novel needle coke-based gas diffusion electro-Fenton cathode (GDEFC) was prepared by pressing a catalytic layer (CL) made from iron-loaded needle coke and a gas diffusion layer (GDL) prepared from hydrophobic needle coke on both sides of a well-conducting titanium mesh. The optimum preparation conditions of the electrode CL are the NaOH modified concentration of 1 mol·L−1, 2 % Fe2+ loading, catalyst calcination temperature at 200 °C and the catalyst and binder doping ratio of 3:1. The doping ratio of needle coke to PTFE is 1:2.5. The GDEFC calcination temperature is 300 °C. When the GDEFC fabricated under the optimal conditions was used to treat coking wastewater under the optimal treatment conditions of applied voltage = 11 V, plat spacing = 1 cm and initial pH = 2.8, the removal rates of COD, color, ammonia nitrogen, thiocyanide and sulfide of coking wastewater are 91 %, 100 %, 100 %, 98.6 % and 86 %, respectively, and the B/C increases from 0.181 to 0.418. Static and dynamic experiments both demonstrated that the GDEFC is a kind of environmentally-friendly electro-Fenton reaction cathode with excellent performance in coking wastewater treatment, which can provide a solid theoretical and experimental basis for the practical application of the electro-Fenton cathode.