Preparation Of High Performance Bioanodes And Adhesion Property Of Its Surface Microorganisms

The Bioelectrochemical system(BES)could use electrochemically active bacteria as catalysts to transform chemical energy in wastewater into electrical energy for further recycling and utilization,which has potential applications in various fields.Bioanodes are core components that affect the performance and cost of BES.This dissertation focused on the preparation of high performance bioanode materials to improve the performance of BES,and discussed the adhesion behavior at the interface of bioelectrode/microorganism from the micro-level.Those strategies provide new options for anode materials of BES and offer an opportunity to understand the interaction at the bioelectrode/microorganism interface.Initially,in order to promote the biological electrochemical performance,mechanical strength of the traditional carbon materials and reduce the cost,select the carbon black as raw material.Carbon nanoparticles in carbon black are modified onto the stainless steel mesh with electro polymerization of pyrrole,which form a conductive polypyrrole layer as the binder.The characterization results show that the modified electrode combined with the advantages of carbon nanoparticles,stainless steel mesh and polypyrrole has good biocompatibility,excellent conductivity and large surface area,which could effectively promote the adhesion of bacteria and the interfacial electron transfer process.In the three-electrode system and the Microbial fuel cell(MFC),the Carbon Nanoparticles/Polypyrrole/Stainless Steel electrodes(CN/PPY/SS)show good performance and stability.Compared with the electrode without carbon nanoparticles,the maximum power density of the MFC with CN/PPY/SS is increased by 1.26 times.What's more,a three-dimensional thermal treated expanded graphite foam(TEGF)was prepared with rapid gasification of liquid nitrogen and thermal treatment,so as to construct three-dimensional porous bioelectrode with large specific surface area.The characterization results indicate that no doping or oxidation occurs during the preparation,which retains a good conductivity and biocompatibility.Cyclic voltammetry and electrochemical impedance spectroscopy are further conducted to investigate the electrochemical performance of different anode materials.Results confirm that the bioelectrochemical activities are enhanced on the fabricated electrodes.Furthermore,MFC equipped with the TEGF exhibit significantly higher power density(228 mW/m2)than graphite foil(24 mW/m2).Electrochemical active surface area measurement reveals that,other than surface area increase,the graphene-like electrode morphology promotes electron transfer processes.At last,the adhesion force between Shewannella oneidensis MR-1 and gold substrate is measured by single-cell force spectrometry in order to better understand the interaction of bioelectrode/microorganism interface and promote the development of bioanode.In this part,the surface charge of the anode is selected as the investigation factor,and the adhesion curve between a single bacterium and the electrode is measured quantitatively from the micro-level.The results reveal that the higher complementary degree between the surface charge of the electrode and bacteria,the higher the adhesion force.The positive charge on the surface of electrode is conducive to the formation of biofilm.