Heterogeneous electro-Fenton oxidation of Congo red using carboxylic group activated carbon felt cathode: Electrokinetic mechanism and performance

In this study, the carboxyl functional group (–COOH) saturated-carbon-felt (ACF) as functional cathode was prepared and used in heterogenous (Fe²⁺) electro-Fenton (EF) catalytic degradation of Congo red (CR) in waster. As a heterogeneous catalyst, size-controlled magnetite (Fe₃O₄) nanoparticles (MNPs) were applied to the surface of the ACF cathode. The selectivity of ACF toward the two-electron oxygen-reduction reaction was estimated based on the proportion of H₂O₂ production; it was determined as >89 %. The removal efficiency of ACF for CR dye was 94 ± 2 % over 40 min reaction time, almost double that of a pristine CF cathode (48 ± 3 %). The kinetics data fitted to a pseudo-second order (PSO) model with K₂ of 8.8 × 10⁻⁴ ± 1.72 × 10⁻⁵ mol⁻¹ cm³ min⁻¹ (0.88 ± 0.02 M⁻¹ min⁻¹). The mineralization current efficiency and TOC for CR were observed as 58 ± 2 %, and 83 ± 3 %, respectively. Overall, the results insight that the system could be a viable alternative method for treating dye-contaminated water.