Research On Modified Cathode Materials In The Treatment Of Refractory Industrial Wastewater By Electro-Fenton Process

In recent years,as one of the important advanced electrochemical oxidation technologies,the electro-Fenton technology has attracted more and more attention in the treatment of refractory organic pollutants.The basic reaction principle of electric Fenton is that dissolved oxygen produces hydrogen peroxide?H₂O₂?through the two-electron oxygen reduction reaction?ORR?on the surface of a suitable cathode material.This method can be used as a very promising environmental repair method.The degradation efficiency of electro-Fenton depends mainly on the electrogeneration capacity of H₂O₂,and the kinetics of oxygen reduction reaction?ORR?is largely dependent on the electrode materials.Based on the current development trend of electrode materials development,we believe that the development of low-cost,green and clean 2e^-oxygen reduction electrocatalytic materials for in-situ electrochemical synthesis of H₂O₂ and highly efficient treatment of refractory organic wastewater is of great significance.At present,carbon-based materials have established a leading position in environmental applications,especially in replacing electrocatalytic conversion of precious metals.Graphene is a two-dimensional carbon nanomaterial composed of carbon atoms and sp² hybrid orbitals.It has been proved to be a highly efficient metal-free ORR catalyst.Therefore,the application of graphene in the electro-Fenton process is considered gradually.Due to the slow kinetics of electrocatalytic oxygen reduction,electrocatalysts for the electro-Fenton process have yet to be developed.Therefore,enhancing the interaction between the target contaminant and the electrode,improving the mass transfer process,and increasing the defects of the electrocatalysts appropriately as active sites are applied for improve the selectivity of 2e^-reduction by the composition of the electrocatalytic material and the design of the surface functional groups.In order to achieve efficient H₂O₂ production performance,it is worth studying and developing.In this paper,we synthesized a nitrogen-doped graphene?N-graphene?metal-free electrocatalyst for this problem,and prepared N-graphene-GF cathode material.The synthesized materials were characterized by scanning electron microscopy?SEM?,Raman spectroscopy,X-ray electron spectroscopy?XPS?,and nitrogen desorption-adsorption?BET?.Moreover,the electron spin resonance?ESR?technique was used to capture free radicals,we found that N-graphene modified graphite felt was more conducive to the conversion of H₂O₂ to?OH than graphene in the process of in-situ H₂O₂ activation to?OH during the research.We applied N-graphene-GF to the electro-Fenton system to study the decomposition and mineralization of the pharmaceutical wastewater phenacetin,and investigated the yield of H₂O₂ and the amount of free radicals.The results showed that N-graphene-GF had good performance in selecting two-electron oxygen reduction reaction to produce H₂O₂.The degradation rate of pollutants in water could reach 98%in two hours,and the COD removal rate was close to 90%.TOC with a removal rate of 76.7%,the material had excellent performances in the degradation and mineralization of pollutants in the electro-Fenton system.