Study On The Construction And Mechanism Of Functional Polymeric Microbe/electrode Interfaces

With promising application prospects,bioelectrochemical systems(BESs)could not only recycle the energy while treating pollutant,but also transform environmental waste into resource products.However,the microbe/electrode interfacial functional mechanism is one of the key scientific problems in this field.In BESs,the electron transfer and physical adhesion are two main connections between microbe and electrode,while the inferior controllability of electron transfer process and bacterial adhesion behavior hinders the performance improvement.In this dissertation,functional polymeric layers between bacteria and electrodes were introduced to solve those above problems.The electron transfer was improved and adjusted,the specific bacteria were selectively enriched at bio-electrode interfaces,which provided the theoretical and technical support for effective and stable operation of BES applications.For the inferior biocompatibility and low electron transfer rate of non-noble metal electrode materials,the polypyrrole(PPY)/active carbon modified method was developed for fabricating the high performance composite anodic material.The sargassum based active carbon(SAC)with high nitrogen content could improve the biocompatibility,meanwhile the Ppy and stainless steel with high conductivity and abundant microstructure could accelerate the electron transfer.The maximum output power density of the MFC with PPY/SAC modified stainless steel anode could reach 45.2 W/m3.The microbe distribution on the anode was more even.The study on electrons transfer dynamics at the bio-electrode interface showed that the concentration of electron-donor in substrate had a major influence on interfacial electron transfer than the electrode potential.Through introducing the stimuli-responsive polymeric interface,the composite cathode was constructed for controling the electron transfer process of MFCs.The pH-responsive polymer,poly(4-vinylpyridine),was grafted onto a cathode of MFC,through coupling the pH variation of electrolyte caused by optical signal,the optical signal controlled switchable MFC output system was constructed.The control of the MFC on/off state by optical signal was achieved.The bacterial type and abundance on electrodes influenced the magnitude and stability of output electric current of BESs.Through developing the method of growing bacteria-imprinted polymers(BIPs)in situ on electrodes,the bacterial selective electrode was constructed for realizing the bacterial specific adhesion on electrodes.The surface-initiated atom transfer radical polymerization was employed,with Shewannella oneidensis MR-1?GFP-Escherichia coli?Staphylococcus aureus and Enterococcus faecalis as templates,two kinds of methacrylic ester monomers with different charge were used for fabricating bacteria-selective electrodes.The bacterial specific adhesion and electron transfer was achieved in S.oneidensis MR-1 inoculated BES reactor by using the BIP electrode.The mechanism study revealed that the charge exhibited on bacterial outer membrane could cause electrostatic interaction with the charge heterogeneously distributed on BIP electrode once the bacterial shape and the imprints on the BIP electrode matched.The higher the charge distribution match degree,the stronger the electrostatic interaction at microbe/electrode interface,and the bigger bacterial adhesion force on electrodes.Therefore,the charge amount and distribution on bacterial selective electrode would have major influence on its bacterial selective adhesion performance.