The Flow-through Heterogeneous Electro-fenton System Based On The Biomass Derived Bulk Carbon Fiber Electrode For The Research Of Refractory Organic Pollutants Treatment

The electro-Fenton reaction is traditionally carried out in a batch or flow-by reactor.However,the electro-Fenton performance is restricted by low utilization efficiency of catalysts,limited contact time of reactants,and the slow mass transfer.In this work,a flow-through heterogeneous electro-Fenton reactor was designed by using absorbent cotton derived three-dimensional carbon fiber network with iron oxide nanoparticles loaded as cathode.This flow-through electro-Fenton system can electrochemically catalyze O₂ molecule to produce·OH.The results obtained are as follows:The absorbent cotton was immersed in FeCl₃ solution and carbonized under Ar to prepare an integrated absorbent cotton-derived carbon fiber electrode inlaid with iron oxide nanoparticles.The iron oxide nanoparticles are embedded in the carbon fiber substrate.The porous structure and high specific surface area(579 m² g^-1)provide plenty of reactive sites,which are conducive to the mass transfer process.Sufficient contact with the carbon fiber base effectively prevents the iron particles from falling off,dissolving and agglomerating,improving the stability of the electrode.The iron element is evenly distributed throughout the electrode,which greatly improves the utilization efficiency of the electrode.The electrode has plenty of defects and sp³-C,which can be used as active sites for the promotion of the two-electron reduction of O₂ to H₂O₂.A flow-through type electro-Fenton reactor was designed,where the bulk cathode,cheap titanium mesh anode and non-woven membrane layer were used to fabricate the reactor.The effects of electrode assembly pattern and flow direction on the pollutant degradation efficiency were investigated.CA mode（cathode above）achieved much higher phenol removal efficiency,and TB mode（from top to bottom）is favorable to obtain low electricity consumption.Phenol(20 mg L^-1)was used as the target pollutant to investigate the flow-through hetero-EF performance of Fe-ACE,and the preparation conditions such as iron content and carbonization temperature in the electrode preparation process were optimized（The iron content was 0.8%,and the electrode carbonization temperature was 700℃）.The operating parameters（applied voltage,solution flow rate,and initial p H value）of the system were investigated,and the optimum condition was be determined to:applied voltage 3.0 V,flow rate 0.15 m L min^-1,initial p H 5.0.During the continuous test,the phenol degradation and mineralization efficiency achieved 92.7%and 65.1%,respectively,demonstrating the efficient and stable performance toward pollutant elimination of flow-through electro-Fenton system.Moreover,the flow-through system was demonstrated to be effective in the p H range of 5～9,and powerful for various refractory organic pollutants degradation including sulfamethoxazole,atrazine and benzoic acid.The removal efficiency of the three pollutants were 77.1%,84.4%and 66.3%,and the TOC removal efficiency were 35.6%,47.3%and28.4%,respectively.The high heterogeneous electro-Fenton activity was mainly attributed to the continuous in-situ·OH generation.This study offers a facile method to construct flow-through heterogeneous electro-Fenton device,which provides a promising technology for wastewater treatment with low cost,high performance and good stability.