The mechanism of Co-based carbon felt flow-through cathode non-homogeneous electro-Fenton system for organic pollutants degradation

Abstract

In this study, a Co-containing modified cathode carbon felt (Co-CF) was prepared for organic pollutants degradation by non-homogeneous electro-Fenton in a novel flow-through reactor. SEM, XRD, XPS, FTIR, RAMAN, LSV and EIS characterization of Co-CF electrodes were carried out to observe the electrode preparation and electro catalytic performance. Co was successfully doped onto CF in a valence of Co⁺² and Co⁺³ and the optimal Co content was obtained at 0.0547 mmol·cm⁻², with a degradation efficiency of 97 % for Acid orange 7 (AO7) at 30 min (k = 0.0801 min⁻¹). It was found that increasing the current density and liquid flow rate as well as decreasing the pH could enhance AO7 degradation rate. The AO7 degradation mechanism in flow-through system was the combination of ^•OH, ¹O₂ and ^•O₂⁻. Co-CF electrode had an excellent performance for five circles degradation (k > 0.0653 min⁻¹) and the Co leaching was lower than the emission standard (<0.2 mg·L⁻¹). The presence of HCO₃⁻, H₂PO₄⁻ and Cl⁻ had no significant effect on AO7 degradation. The possible AO7 degradation pathway was proposed. The technique has a good application for azo dye wastewater treatment with an average rate constant of 0.0925 min⁻¹.