Carbon felt/ CoFe ₂ O ₄ cathode synthesis and use in the heterogeneous electro‐Fenton process for vanillin oxidation

Synthetic vanillin is widely used in industries such as food and cosmetics, and it is also produced as a by‐product in various processes. This study was conducted to compare the degradation of vanillin using homogeneous and heterogeneous electro‐Fenton (EF) processes. Initially, electrocatalytic characterization was performed on a cathode material synthesized by solvothermal deposition of cobalt ferrite (CoFe 2 O 4 ) nanostructures onto a carbon felt (CF) substrate and compared with bare CF. Subsequently, the effectiveness of the CF@CoFe 2 O 4 cathode material in vanillin oxidation was compared at different pH values and currents with the heterogeneous electro‐Fenton process. The highest vanillin degradation and total organic carbon (TOC) removal were achieved at pH 3. Following a 3 h heterogeneous EF process at 50 mA, 100% degradation, and 74% TOC removal were achieved, while the electrode's performance remained unchanged after 5 reuses. This study reports the first‐time use of a CF@CoFe 2 O 4 cathode in the electro‐Fenton degradation of vanillin, achieving faster and more efficient removal than a conventional CF cathode while ensuring stability, low metal ion leaching, and environmental compatibility for sustainable treatment of persistent organic pollutants. Vanillin degradation was further accelerated at pH 3 due to reduced mass transfer limitations, enhanced hydroxyl radical generation from controlled metal ion leaching, and a more efficient redox cycling of metal ions.