Fabrication of a novel gas diffusion electrode (g-C3N4/CB/PTFE-GF) for electro-Fenton treatment of amaranth dye

It is of great importance to find suitable electrode materials to degrade dyes wastewater in electro-Fenton system. In this work, a novel gas diffusion electrode (g-C3N4/CB/PTFE-GF) was prepared by modified with graphitic carbon nitride (g-C3N4), carbon black (CB) and polytetrafluoroethylene (PTFE) on the surface of graphite felt (GF). According to the production of H2O2, the performance of g-C3N4/CB/PTFE-GF is significantly higher than GF electrode and CB/PTFE gas diffusion electrode, while optimum preparation parameters were determined, i.e. the mass ratio of g-C3N4 to CB = 1:1, PTFE = 2 mL, calcination temperature = 350 °C. Physicochemical analysis indicated the introduction of g-C3N4 and the presence of CC increase current efficiency and the activity of 2e− ORR process and electrocatalysis, thereby promoting H2O2 generation. The single and combined effects of the current density, pH, Fe2+ concentration, initial amaranth concentration, and reaction time on amaranth degradation were further investigated. Based on the optimization of response surface methodology, amaranth removal efficiency of 96.98 % was achieved with the following condition: 200 mg/L initial amaranth concentration, 4 mA/cm2 current density, 3.0 pH, 0.1 mM Fe2+ concentration, and 70 min reaction time. The g-C3N4/CB/PTFE-GF electrode possessed excellent stability and recyclability, as revealed by amaranth removal efficiency of >89 % after ten consecutive cycles. A potential amaranth degradation pathway was proposed based on the quenching test, UV–vis spectra, and HPLS-MS. In this study, a novel gas diffusion electrode with high performance and stability is provided for the treatment of refractory dye wastewater by electro-Fenton oxidation.