Investigations On The Bioelectrochemical Characteristics Of Carbon Felt And Stainless Steel Felt Anodes Modified With The Different Methods

Microbial fuel cell（MFC）is a device that converts chemical energy into electrical energy by oxidizing and decomposing organic substances through electrochemical bacteria.However,the electricity production performance of microbial fuel cells is very low,which limits the practical application and development of MFC.There are many factors controlling the production performance of microbial fuel cells,and the key factor is electron transfer efficiency between the microorganism and the anode.Therefore,anode materials have become one of the most important factors.By modifying the electrode,selecting an inexpensive and excellent anode material to improve electrochemical activity and biocompatibility of the anode,and reduce the internal resistance of electron transfer,and then achieve the purpose of improving the power production performance of MFC.In this paper,graphene,manganese dioxide（MnO₂）,anthraquinone（AQS）,and conductive polymer polypyrrole（PPy）were used to modify different anode materials（carbon felt,stainless steel felt）,and further analyzed the effect of the performance of MFC with the above electrodes as anodes.The interaction between electrodes and microbes,explored the effect of anode modification on its electrochemical performance and biocompatibility by carried out the cyclic voltammetry（CV）,electrochemical impedance spectroscopy（EIS）,and scanning electron microscope（SEM）were studied.The main contents were summarized as follows:（1）Investigation on the performance in the Microbial Fuel Cell with the Stainless Steel Anode Modified by Mn O₂&Dioxide GrapheneGO was modified on the surface of the stainless steel felt（SS）by immersing the SS electrode in the GO suspension,and then got the SS-GO anode;SS-GO was reduced to SS-r GO through a constant voltage method;Mn O₂was modified on the surface of SS and SS-r GO by CV electrodeposition method with scanning 20 turns,SS-Mn O₂ anode and SS-r GO-Mn O₂anodes were prepared.Anodes perpared above and bare SS anode were used as comparasion by cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）.The results showed that the capacitance of the SS-r GO-Mn O₂anode before the MFC operation was the lagest,the value was 0.019μF,its internal resistance of transfer was the lowest,the value of R_ct was 66.07Ω,which was 99%and 96%lower than those of SS anode(R_ct=12410Ω)and SS-MnO₂ anode(R_ct=1908Ω),respectively.In MFC,the power density of MFC with SS,SS-MnO₂,SS-rGO,and SS-r GO-Mn O₂ as anodes were 227.6 m Wm^-2,98.9 m Wm^-2,353.4 m Wm^-2,and 517.5 m Wm^-2,respectively,the power density of MFC with SS-r GO-Mn O₂as the anode was the largest,and its power production voltage can be as high as 0.40 V（external 750Ωresistor）.After used the SEM,SS-r GO-Mn O₂ anode had the most microbial load.Mn O₂ and r GO modified on the surface of SS,the biocompatibility and electrochemical performance of the SS have been significantly improved,it proved that the SS-r GO-Mn O₂ anode was an excellent anode material for MFC.（2）Application of the Stainless Steel Anodes Modified by anthraquinone&polypyrrole in Microbial Fuel CellThe anthraquinone（AQS）and polypyrrole（PPy）were modified on the surface of stainless steel（SS）anodes by a constant voltage method,AQS-SS anode and AQS-PPy-SS anode were prepared,and bare SS anode were used as comparasion cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）.It found that the capacitance of the AQS-PPy-SS anode before the MFC operation was the lagest,the value was 0.08μF,and had the lagest scanning area,its internal resistance of transfer was the lowest,the value of R_ct was 2.85Ω,which was 99%and 99.9%lower than those of SS anode(R_ct=2593Ω)and AQS-SS anode(R_ct=1223Ω),respectively.In MFC,the power density of MFC with SS,AQS-SS and AQS-PPy-SS as anodes were 37.12m Wm^-2,80.5 m Wm^-2 and 648.2 m Wm^-2,respectively,the power density of MFC with AQS-PPy-SS as the anode was the largest,and its power production voltage can be as high as 0.45 V（external 750Ωresistor）.SEM showed AQS-PPy-SS had the most microbial load AQS and PPy modified on the surface of SS,biocompatibility and electrochemical performance of SS have been significantly improved,it proved that AQS-PPy-SS anode was an excellent anode material for MFC.（3）Application of the carbon felt Anodes Modified by anthraquinone&polypyrrole in Microbial Fuel CellAnthraquinone（AQS）and polypyrrole（PPy）were modified on the surface of carbon felt（CF）anodes by a constant voltage method,AQS-CF anode and AQS-PPy-CF anode were prepared,and bare CF anode were used as comparasion cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）.In this part,before the MFC operation,the AQS-PPy-CF had the maximum CV response current,the capacitance of AQS-PPy-CF was the lagest,the value was 0.023μF,its internal resistance of transfer was the lowest,the value of R_ct was 23.16Ω,which was79%and 81%lower than those of CF anode(R_ct=113Ω)and AQS-PPy-CF anode(R_ct=121.8Ω),respectively.In MFC,the power density was measured at 90^th hour,the power density of MFC with CF,AQS-CF and AQS-PPy-CF as anodes were 41.91m Wm^-2,356.65 mWm^-2 and 127.79 mWm^-2,respectively.The power production voltage of MFC with AQS-PPy-CF can be as high as 0.25 V（external 750Ωresistor）.SEM showed that AQS-PPy-CF anode had the most microbial load.Different modification strategies to modify different anodes were used,research on electron transfer ability of the modified anodes and electricity production performance of MFC showed that AQS-PPy-SS anode had a lower internal resistance of transfer than SS-r GO-Mn O₂ anode,the charge transfer quanity was also improved.Electricity generation performance of MFC with AQS-PPy-SS as the anode had also significantly improved.During the modification of different anodes by the same material,AQS and PPy modified the stainless steel felt（SS）and carbon felt（CF）,respectively.After characterized by cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）,power production performance of MFC was analyzed,it was found that performance of the electrode modified by stainless steel felt as the base material was better than that of carbon felt.