Degradation Of Rhodamine B By Modified Carbon-graphite Felt Cathode Electro-fenton Method

With the acceleration of world industrialization and the research and development of various new energy technologies,the efficiency and application of electric energy in industrial production have been greatly improved.Electric Fenton technology is developed on the basis of Fenton technology.As a green,clean and environmentally friendly new technology for wastewater treatment,it has great prospects for development.Printing and dyeing wastewater is one of the refractory industrial wastewater.Its various toxic effects have caused serious threat to the ecological environment and human health.Therefore,the research and development of an efficient and thorough treatment method for the removal of refractory biodegradable components in polluted water has become a hot spot of current research.In this study,graphite felt was used as matrix material,and a cathode material with high efficiency of producing hydrogen peroxide was prepared by chemical modification.The degradation of Rhodamine B?RhB?by electroFenton method with modified graphite felt as cathode was investigated.Graphite felt was modified by ethanol-hydrazine hydrate system and mixed solution containing iron and manganese ions in turn.Scanning electron microscope characterization and contact angle measurement showed that a large number of carbon nanoparticles were attached to the surface of the modified material,which improved the hydrophilicity and hydrogen dioxide production efficiency of graphite felt.X-ray Diffraction and X-ray Photoelectron Spectroscopy analysis showed that the oxygen-containing groups on the surface of the modified carbon fibers increased,and the main forms of introducing nitrogen elements were pyrrole-type nitrogen structure,pyridine-type nitrogen group and nitrogen oxide group.The specific states of iron and manganese oxides on carbon fibers are Fe₂O₃?Fe₃O₄ and Mn₃O₄ respectively,which improves the cyclic regeneration ability of Fe²⁺on the cathode surface and the catalytic reduction ability of O₂ to a certain extent.The results of comparative experiments show that the most amount of hydrogen peroxide is produced by CF-3 modified material,up to 180.3 mg/L.The modified electrode can improve the degradation effect of RhB by Fenton reaction.The highest removal rate is 97.9%,which is 12.3%higher than that of the unmodified electrode.The degradation mechanism of RhB by modified graphite felt cathode electroFenton method was investigated.Two oxidation mechanisms were found in the reaction process.One is the direct oxidation of RhB by the anode through the loss of electrons on the surface of the anode,and the other is the indirect oxidation,which is based on the continuous oxidation reaction of the active substances produced in the system with RhB and its intermediate by-products.The effects of electrolyte concentration,current density,Fe²⁺concentration,initial RhB concentration,initial pH value,aeration rate and temperature on the degradation of RhB by electroFenton cathode were investigated.The results show that the electrolyte Na₂SO₄ concentration is 0.1 mol/L,current density is 24 mA/cm²,ferrous ion concentration is 0.5 mol/L,initial concentration of RhB is 15.5 mg/L,aeration is120 mL/min,and temperature is between 14³4?.The modified cathode electroFenton method can degrade RhB effectively.The highest degradation rate of RhB can reach97.9%after 120 min of reaction.