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

Abstract

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. © 2020 Elsevier B.V.