Modification Of Cathode Materials In Electro-fenton And Its Performance In Degradation Of Dimethyl Phthalate

As a kind of advanced electrochemical oxidation technology,Electro-Fenton technology（EF）is clean and efficient,which has attracted a great deal of attention in recent years.However,the traditional（EF）system has the problems of low H₂O₂ yield,low current efficiency and poor operating efficiency.Since the production of H₂O₂ is significantly dependent on the cathodes used,so developing new efficient cathodic materials becomes one of the research focues..In this study,in order to improve the catalytic activity of the oxygen reduction reaction on the cathode surface,the graphite felts with three-dimensional structure were used as supporter,the catalytic layer is made by nonmetallic doping,a new modified cathode material was prepared by loading the catalytic layer to the pretreated carbon felt.The material was modified by the non-metal doping method.The effect of the modification process on the yield of H₂O₂ was systematically investigated by the electrochemical performance test and the material characterization In addition,selecting the efficent modified materials as cathode in EF to remove dimethyl phthalate（DMP）,impacts of the operational parameters were studied,and the reaction mechanism of the DMP degradation process was preliminarily explored.The cheap and readily available melamine and boric acid are used as nitrogen source and boron source.Investigating the effects of modification process on the material properties.The results showed tha the mass ratio of carbon to melamine in catalytic layer was 1:0.1,the efficiency was the highest 149.6 mg/L.When the mass ratio of carbon,melamine and boric acid was 1:0.1:0.05,the highest yield of H₂O₂ is 160 mg/L,the effect is slightly better than that of nitrogen doping.The membrane solution（Nafion）was 0.15 g/m L,The optional temperature was 150℃.The electrochemical properties of the materials were tested by cyclic voltammetry curves.It was found that the nitrogen doping and nitrogen and boron doped materials could improve the current response value and promote the electron transfer process.The modified materials were characterized by scanning electron microscope,X ray photoelectron spectroscopy,X ray diffraction analysis and specific surface area measurement.Those showed that material surface and internal structure have changed.The operating conditions of EF are optimized by single factor experiment on the initial pH value,voltage,oxygen supply mode and plate spacing of the influence factors of electric Fenton process.The results show that the DMP needs 60 min to be completely degraded in the nitrogen doped system while the voltage 2.1 V（pH is about 5）,the voltage 2.1 V（cathode potential-0.69 V）,uninterrupted aeration and the spacing of 1 cm,and the nitrogen and boron doping system only needs 30 min;and the DMP removal process in the system can be described by a quasi first order kinetics.The fitting of the kinetic constants are consistent with experimental results.Modified materials after used for 15 times,still has good stability.The prepared materials are used to treat the actual wastewater（landfill leachate and domestic sewage）.After 2h,the removal rate of DMP is 49.97% and 61.04% respectively,which is far below the actual removal rate of water distribution.The degradation process of DMP was explored.The UV full scanning spectrum showed that DMP appeared two characteristic absorption peaks at 229 nm and 276 nm,and the peak value gradually decreased with time.By changing the anodic and quenching experiments,the inhibition degree of DMP removal in the system was measured,and the existence of hydroxyl radical（.OH）in the system was verified,and Fe2+ was generated.OH an indispensable condition.This study showed that the modified cathode materials with nitrogen and boron doping can improve the oxygen reduction performance（ORR）and the operation efficiency of EF.