Co-N-doped MoO 2 modified carbon felt cathode for removal of EDTA-Ni in electro-Fenton process

摘要

Metal ions removal is inhibited in aqueous solution containing ethylenediaminetetraacetic acid (EDTA). In this study, the non-noble metals-based Co-N-doped MoO~(2)nanowires (Co-N-MoO~(2)) were successfully synthesized using cyanamide and Co(Ac)~(2)as precursors by pyrolysis, then immobilized on carbon felt (CF), and firstly used as cathode to remove EDTA-Ni complex through oxygen reduction reaction (ORR) in electro-Fenton (EF) process. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results indicated that a synergetic coupling effect of doping of N and Co induced structural modifications of MoO~(2)lattice, and produced more lattice defects. The electrochemical analysis results showed that the superior ORR electrochemical catalysis activities were obtained at pH?=?3 with the lowest cathodic peak potentials (??0.157?V vs. Ag/AgCl), the highest electrochemical active surface area (EASA: 3.971?mC?cm_(?2)), the extraordinarily high of the ring current (35.5?μA) and high H~(2)O~(2)yield (>?20%). Under the optimum conditions, about 68% of EDTA-Ni was removed with the Co-N-MoO~(2)/CF as cathode after 120?min with lower specific energy consumption (0.0226?kW?h?mg_(?1)(DOC)) in EF system. Mechanism analysis indicated that the production of strong oxidizing property of hydroxyl radical (?OH) on the cathode played an important role in the removal of EDTA-Ni in the EF process, synergetic effect of cobalt and nitrogen co-doped could facilitate the high generation of H~(2)O~(2), which greatly promote the formation of ?OH. The EF system with Co-N-MoO~(2)/CF cathode has a potential for breaking metal-complex with good stability, showing that this cathode is a candidate for application for applications in EAPOs.