The Dual-system Coupling Mechanism Enhances The Efficiency Strategy Of Electro-fenton

With the application of plastic products,the endocrine disruptors in the waste are more and more concerned with the potential adverse effect of the public health.In recent years,due to the low cost and high efficiency advantageof the EF technology in the field of waste water treatment research,it has become an important research object in the AOPs technology.During the EF process,the content of the H₂O₂ produced by the electrocatalysis of the cathode generally determines the amount of the oxide species,·OH,required to degrade the organic contaminants,thus determining the efficiency of the EF operation,Therefore,setting the 2e-ORR favorable potential for EF degradation has become a recognized method of operation.However,since（1）the concentration of dissolved oxygen in the electrolyte is low（2）2e-ORR isthe electrode process of the multi-electron participation,the potential for 2e-ORR in thegeneral case is much higher than the optimum FeRR potential.A single higher potentialis used to control the degradation process of EF,although a considerable H₂O₂electrocatalytic yield may be available,but this means of operation does not seem togive full play to the maximum degradation potential of EF since the FeRR is suppressedat higher potential.However,if a lower constant potential operation EF is apply,while that cathode has a more suitable Fe²⁺condition,the EF efficiency will eventually bereduced due to an insufficient output of H₂O₂.Therefore,it is of great significance tosolve the contradiction between 2e-ORR and FeRR electrode process,so as to releasethe potential of degradation efficiency.And finally,the purpose of improving the EFefficiency and reducing the energy consumption is achieved.Strategy 1.Homogeneous Electro-Fenton Degradation of Organic Pollutants by Dual Cathode Dual SystemThe FeRR system is introduced on the basis of the traditional electro-Fenton to form a dual-system electro-Fenton.In this system,the optimum electrode potential of graphite felt as oxygen reduction cathode is-0.9 V vs.SCE,and the optimum potential of graphite felt as iron reduction electrode is 0 V vs.SCE.In 100 m L system p H=3,0.1m M Na₂SO₄ electrolyte,DMP initial concentration 0.25 m M·L^-1,adding 0.4 m M Fe³⁺,can remove DMP up to 97.82%.Under this system,the degradation was repeated 5times,and 98.28%of the pollutants could still be degraded in 30 minutes.For plasticizers and derivatives of plasticizers,it has a good degradation effect.At the same time,69.3%of the pollutants can be mineralized in 120 min,and the energy consumption is 2.355×106 k J·kg^-1TOC^-1,which is lower than that of the traditional electro-Fenton system.The introduction of FeRR system can improve the reduction of Fe²⁺in the system,increase the generation of hydroxyl radicals and improve the degradation efficiency.Strategy 2.Heterogeneous Electro-Fenton Degradation of Organic Pollutants by Dual Cathode Dual SystemElectro-Fenton focused on how to efficiently produce hydrogen peroxide and neglected the iron reduction process.This article proposes a new method,on the basis of the traditional single-electrode system,an Fe₃O₄ supported graphite felt（Fe₃O₄@GF）electrode is introduced to form a double-cathode electro-Fenton.And at the same time,a flow-through reactor is used to explore and test the optimal potential and the performance of the system through the degradation experiment of dimethyl phthalate.Experimental results show that the best oxygen reduction cathode potential is-0.6 V vs.SCE and the best Fe₃O₄@GF cathode potential is 0.1 V vs.SCE in the double cathode electro-Fenton system.Under the above conditions,in 150ml of concentration of Na₂SO₄ 0.1 mol L^-1,concentration of DMP 0.25 mmol·L^-1 solution,flow rate of O₂ 0.3L·min^-1,p H=3,DMP removal rate reach 93.7%after 60 minutes,which is 5 times the degradation effect of traditional heterogeneous electro-Fenton.Strategy 1.Single-cathode dual-system multiphase electro-Fenton degradation of pollutantsThe graphite felt was simply pickled and soaked in 4m MFeCl3,and then heated in a muffle furnace at 220°C for 1 h to synthesize Fe OCl electrodes.0.1 m M DMP can be degraded within 45 min by switching the dual system through potential oscillation between the oxygen reduction potential of-0.9 V and the iron reduction potential of-0.1 V.After 5 cycles after activation by HCl,the dual-system electro-Fenton can still degrade 89.70%of DMP.Through the quenching and trapping of free radicals,it is found that the main effect of electro-Fenton in the single-cathode system is to increase the yield of OH and improve the ability of pollutant degradation.