| In order to realize in-situ utilization of weak current generated in microbial fuel cell?MFC?,an MFC-EF coupling system was constructed by combining the advantages of electro-Fenton?EF?technology.To further improve the performance of the coupling system,a composite cathode of iron and manganese?FeMnOx/CF composite electrode,CF refers to carbon fiber brush?was prepared,which introduced Fenton-like catalyst manganese on the basis of Fenton catalyst iron.The electrochemical performance of MFC-EF coupling system and its degradation effect on Rhodamine B?RhB?were investigated by comparing it with the CF unloaded electrode and Fe&Fe2O3/CF composite electrode.The electrode materials were characterized and analyzed by SEM,EDS and XPS.The electrochemical performance of the MFC-EF was analyzed according to the parameters of voltage,electrode potential,polarization curve and power density curve.The degradation ability of the coupling system to pollutants was evaluated by the production and current efficiency of hydrogen peroxide,removal rate of RhB and TOC.The results showed that FeMnOx/CF composite electrode was successfully loaded with the binary metal oxides of Fe and Mn.The surface roughness and contact area of the electrode increased,which improved the mass transfer efficiency of the electrode.As a cathode material for MFC-EF coupling system,FeMnOx/CF composite electrodes could simultaneously realize the in-situ production and utilization of electric energy,hydrogen peroxide and Fenton-like catalysts?iron and manganese ions?,and achieve the purpose of degradation and mineralization of pollutants.Compared with the CF unloaded electrode and Fe&Fe2O3/CF composite electrode,the maximum output power of the coupling system was improved(5.47 W·m-3),the internal resistance of the MFC was reduced?109.00??,and both the removal?91.60%?and mineralization rate?30.84%?of RhB were increased with the FeMnOx/CF composite electrode.FeMnOx/CF composite electrode has good stability and can still maintain a high removal rate of RhB after repeated use.The optimum conditions for power generation and RhB degradation of MFC-EF coupling system were determined by optimization experiments.That was,when the initial pH of cathode solution was 3,the external resistance was 10?,the aeration volume of cathode chamber was 400 mL·min-1,and the initial concentration of RhB was 10 mg·L-1,the degradation effect of RhB in MFC-EF coupling system achieved the best.At this time,the RhB removal rates in the coupling system of Fe&Fe2O3/CF composite electrode and FeMnOx/CF composite electrode were 87.05%and 96.66%respectively.At the same time,it was proved that the FeMnOx/CF composite electrodes was free from the strict restriction of catholyte pH in conventional Fenton system,and the pH range of catholyte in MFC-EF coupling system was expanded.The cathode EIS analysis of the MFC-EF coupling system showed that the increase of the power generation of the MFC-EF coupling system with FeMnOx/CF composite cathode was related to the decrease of the internal resistance.Through the analysis of removal pathway and radical inhibition experiments,it was known that the adsorption of carbon brush,the oxidation of hydrogen peroxide and the oxidation of reactive oxygen species generated by electro-Fenton-like reaction all contributed to the removal of RhB in MFC-EF coupling system.however,the mineralization of RhB mainly depended on the process of electro-Fenton and electro-Fenton-like.Three-dimensional fluorescence and ultraviolet-visible full scanning were used to analyze the changes of RhB molecule in the degradation process.The results showed that RhB molecule was degraded step by step,the original group was destroyed,decolorization was achieved,and RhB concentration decreased significantly.However,RhB could not be completely mineralized due to the incomplete destruction.The study can realize the regeneration and utilization of resources in the process of pollutant removal,which is expected to provide a new idea for practical dye wastewater treatment. |
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