In-situ synthesis of 3D GA on titanium wire as a binder-free electrode for electro-Fenton removing of EDTA-Ni

Ethylenediaminetetraacetic acid (EDTA) could form stable complexes with toxic metals such as nickel due to its strong chelation. The three-dimensional (3D) macroporous graphene aerogels (GA), which was in-situ assembled by reduced graphene oxide (rGO) sheets on titanium wire as binder-free electrode, was presented as cathode for the degradation of EDTA-Ni in Electro-Fenton process. The X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and Brunauer-Emmett-Teller (BET) results indicated 3D GA formed three dimensional architecture with large and homogenous macropore structure and surface area. Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV) and Rotating Ring-disk Electrode (RRDE) results showed that the 3D GA cathode at pH 3 displayed the highest current density and electrochemical active surface area (ECSA), and better two electron selectivity for ORR than other pH value, confirming the 3D-GA cathode at pH 3 has the highest electrocatalytic activity and generates more H2O2. The factors such as pH, applied current density, concentration of Fe2+, Na2SO4, and aeration rates of airwere also investigated. Under the optimum conditions, 73.5% of EDTA-Ni was degraded after reaction for 2 h. Mechanism analysis indicated that the production of H-center dot on the 3D GA cathode played an important role in the removal of EDTA-Ni in the 3D GA-EF process, where the direct regeneration of Fe2+ on the cathode would greatly reduce the consumption of H2O2. Therefore, it is of great promise for 3D-GA catalyst to be developed as highly efficient, cost-effective and durable cathode for the removal of EDTA-Ni. (C) 2017 Elsevier B.V. All rights reserved.