An efficient system for electro-Fenton oxidation of pesticide by a reduced graphene oxide-aminopyrazine@3DNi foam gas diffusion electrode

A stable rGO-AmPyraz@3DNiF gas diffusion electrode was prepared via modification of 3D nickel foam (3D-NiF) with aminopyrazine functionalized reduced graphene oxide (rGO-AmPyraz) for the electro Fenton (EF) process. The generation capacity of H₂O₂ and OH radicals by this electrode was assessed relative to 3DNiF and rGO-AmPyraz@indium tin oxide (ITO) electrodes and with/without a coated Fe₃O₄ plate. The rGO-AmPyraz@3DNiF electrode showed the maximum production of these radicals at 2.2 mmol h⁻¹ and 410 μmol h⁻¹, respectively (pH 3) with the least leaching of Ni²⁺ such as < 0.5 mg L⁻¹ even after 5 cycles (e.g., relative to 3DNiF (24 mg L⁻¹). Such control on Ni ion leaching was effective all across the tested pH from 3 to 8.5. Its H₂O₂ generation capacity was far higher than that of the nanocarbon supported on commercially available ITO conductive glass. The mineralization of dichlorvos (at initial concentration: 50 mg L⁻¹) was confirmed with its complete degradation as the concentrations of the end products (e.g., free Cl⁻¹ (5.36 mg L⁻¹) and phosphate (12.89 mg L⁻¹)) were in good agreement with their stoichiometric concentration in dichlorvos. As such, the proposed system can be recommended as an effective electrode to replace nanocarbon-based product commonly employed for EF processes.