Study On Properties Of Metal Oxide Modified Carbon Felt Cathode In Electro-fenton System To Degrade Ciprofloxacin Wastewater

With the development of the pharmaceutical industry and drug consumption in China,a large number of residual drugs are entering the environmental water.Research shows that ciprofloxacin（CIP）is much difficult to be degraded by microorganisms and cannot be effectively removed by conventional water treatment process.However,the electrocatalytic advanced oxidation process（EAOP）which is based on hydroxyl radicals（OH）produced by the reaction of H₂O₂ generated by the reduction of O₂ and Fe²⁺can reduce the residual concentration of CIP in the environment.Therefore,the high yield of H₂O₂ generation is the main concern with the electro-Fenton system.In this paper,we take the three-dimensional carbon felt（CF）which has porous structure as conductive material,Ce_xA_1-xO₂/CF（A=Zr,Cu,or Ni）cathode composites and RGO/Ce-WO₃/CF（RCW/CF）cathode composites were successfully prepared by the impregnation method and the hydrothermal synthesis method,respectively.The morphology and structure of the composite electrodes were analyzed by SEM,TEM,XRD,BET and XPS.The electrochemical properties of the composites were analyzed by CV and EIS.The effects of CF,Ce_xA_1-xO₂/CF（A=Zr,Cu or Ni）and RCW/CF cathode composites on the degradation of ciprofloxacin were investigated by HPLC and TOC.We studied the influence of the current intensity,the amount of catalyst Fe²⁺,the load capacity,the ratio of Ce with A and W,and the ratio of RGO and Ce-WO₃（CW）on the effect of the efficiency of electro-catalytic oxidation degradation of ciprofloxacin.Getting the following main results:1.The degradation efficiency of CIP in electro-Fenton process was studied by metal oxide/carbon felt cathode materials.The cathode had the highest efficiency for electrocatalytic degradation of ciprofloxacin under the experiment condition of pH=3,0.1 mmol·L^-11 Fe²⁺and 400 mA.2.For Ce_xA_1-xO₂/CF cathode composites,when their respective load capacity was constant,the optimum mass ratios of Ce with Zr,Cu and Ni were 0.75:0.25, 0.90:0.10 and 0.85:0.15,respectively;when their respective ratios remain constant,the optimum load capacity of Ce_0.75Zr_0.25O₂,Ce_0.90Cu_0.10O₂ andCe_0.85Ni_0.15O₂ on CF were 2.0 wt%,2.5 wt% and 0.45 wt%,respectively.For RCW/CF cathode composites,the optimum mass ratio of R/CW was 1:3,the optimum molar ratio of Ce/W was 0.05,and the optimum loading of RCW was 4.5 wt%.3.The electrocatalytic properties of five kinds of cathode composites were studied and the electrocatalytic activity was found to be RCW/CF（?）Ce_0.75Zr_0.25O₂/CF> Ce_0.90Cu_0.10O₂/CF>Ce_0.85Ni_0.15O₂/CF>CF.4.Five kinds of cathode composites electrochemical H₂O₂ process was studied.The yield of H₂O₂ was found to be CF>Ce_0.85Ni_0.15O₂/CF>Ce_0.90Cu_0.10O₂/CF> Ce_0.75Zr_0.25O₂/CF>RCW/CF.This was because Ce³⁺and H₂O₂ underwent Fenton-like reactions to produce·OH,and the electrocatalytic activity was RCW/CF（?）Ce_0.75Zr_0.25O₂/CF>Ce_0.90Cu_0.10O₂/CF>Ce_0.85Ni_0.15O₂/CF>CF.5.Degradation efficiency of CIP in descending order is RCW/CF= Ce_0.75Zr_0.25O₂/CF>Ce_0.90Cu_0.10O₂/CF>Ce_0.85Ni_0.15O₂/CF>CF;TOC removal rate in descending order is RCW/CF>Ce_0.75Zr_0.25O₂/CF>Ce_0.90Cu_0.10O₂/CF> Ce_0.85Ni_0.15O₂/CF>CF.6.With the electro-Fenton process,CIP gradually became mineralized and broke down into small molecules.The process relied mainly on·OH generated by the system.