Electro-fenton Oxidation Of P-nitrophenol With Fe/CHI-MWCNTs Modified Graphite Cathode

In recent years, Fenton technology, as an environment-friendly technology, has become a hot topic in the field of refractory organic wastewater treatment. In acidic medium, electric-Fenton using electrochemical method to reduce O2to H2O2on the surface of the cathode, and the H2O2reacts with Fe2+to generate·OH, thus the organic pollutants was oxidatively degraded. In comparasion with the traditional Fenton method, electric-Fenton method has the following advantages:(1) avoiding the potential risks during the transportation and storage of H2O2, and cost savings;(2) in the system, H2O2and Fe2+are produced at a stable rate, and less iron sludge;(3) organic pollutants can be efficiently removed through collaborative hydroxyl radical oxidation, anodic oxidation with electric-adsorption. Although electric-Fenton technology has many advantages, the low efficiency of the electrode current limited its large-scale application, and the development of new efficient cathode material is still necessary.The usual cathode material include graphite electrode, activated carbon fiber, reticulated porous carbon and the gas diffusion type. Carbon nanotube has showed many characteristics, such as large surface area, good electrical conductivity, high strength and hardness. However, the carbon nanotubes composite material should be modified to remedy its poor dispersibility in water.In this research, biocompatibility natural polymer chitosan is used to change the surface structure of multi-walled carbon nanotubes(MWCNTs), in order to disperse MWCNTs can be uniformly dispersed in the solution; while Fe2+fixed on CHI-MWCNTs by impregnation; and the gas diffusion electrode was prepared by mixing this Fe/CHI-MWCNTs, graphite powder and PTFE with the mass ratio2:8:5. In the electrical-Fenton experiments, this new gas diffusion electrode combined with PbO2electrode was regarded as a system, and the4-nitrophenol as a model contaminant. The effect of the FeSO4solution concention, pH value and current density on degradation rate of p-nitrophenol were studied, and the stability of electrode was also investigated in order to provide a reference for further electric Fenton technology practice.The experiental results indicated that the p-nitrophenol removal rate was up to89.98%at60min under the following experiental conditions:graphite cathode modified by Fe/CHI-MWCNTs (the FeSO4concentration is10.0g/L), original p-nitrophenol concentration of100mg/L, initial pH of3.0, current density of3.0mA/cm, Na2SO4concentration of0.05mol/L, air aeration rate of0.1m3/h. In addition, the H2O2generated on the cathode reached148μmol/L, and the concentration of Fe3+was1.52mg/L within90min under this conditions. The prepared electrode has good stability and the retainable activity can be retained when the electrode was used repeatedly for810minutes.