The Study On Anode Modification Method Based On Carbon Nanotubes And Its Application In Microbial Fuel Cells

Microbial fuel cells(MFCs)are an emerging green energy device that can convert chemical energy in a carbon source into electricity through a special mechanism of electroactive microorganisms.In addition to the power output of MFCs,it also has high application value in sewage treatment,seawater desalination,and heavy metal degradation.However,due to the unstable factors such as low output power,high application costs,and harsh starting conditions at the current stage,MFCs have limited their large-scale commercial applications.Among them,the anode performance of MFCs greatly affects the improvement of its output power,and the electron transfer efficiency between the electroactive microorganisms and the anode surface is the most critical factor.In order to promote anode electron transfer,the most feasible method is to optimize the surface structure and electrochemical performance of the anode,so that it is conducive to the adhesion of electroactive microorganisms and quickly conduct the generated electrons.Therefore,finding an innovative and efficient anode modification method is an important way to improve the power generation performance of MFCs.Generally,carbon-based materials are widely used as anode materials for traditional MFCs because of their stability and bioaffinity.However,its conductivity and surface area need to be further improved.This study uses carbon nanotubes(CNTs),a high aspect ratio and high conductivity carbon nanomaterial,to modify traditional carbon materials with its efficient electron receiving and conducting capabilities and easy modification.Based on the excellent properties of CNTs,enhanced contact between electroactive microorganisms and the anode and fast electron transfer are promoted through different modification methods.This study explores the feasibility of different modification methods and optimization schemes to maximize functional release,and uses Shewanella as an electricity-producing microorganism to apply CNTs-modified anodes to double-chamber MFCs to evaluate its electricity generation performance.The specific research content is as follows:First,a new type of carbon nanotube multilayer modified MFCs anode was constructed by using a layer-by-layer self-assembly method to alternately assemble positively charged polyethyleneimine and negatively charged CNTs through electrostatic interaction.The electrochemical catalytic activity of the assembled multilayer film,the morphology of the anode,and the anode performance in the MFC system were studied.Secondly,a new method for manufacturing high-efficiency CNTs modified electrodes by welding assembly was developed.CNTs and polyelectrolytes were assembled layer by layer on an electrode,and then a complete and electrically conductive 3D network structure was formed by welding.The excellent bacterial adhesion and electron transfer performance of the 3D network structure give MFC a higher power density.Finally,the performance of MFCs was verified by changing the operating parameters of MFCs,which stimulated the maximum output power of MFCs under the best conditions.At the same time,the successful application of the efficient anode prepared in MFCs was proved.Considering the p H of the anolyte and the operating cycle,it has been proven from an application perspective that the welded CNTs network can promote the transfer of electrons between the microorganism and the anode material interface,thereby enhancing the formation of the anode biofilm and the power density of the corresponding MFCs.This thesis provides a simple and controllable new method for preparing high-performance and low-cost MFCs anodes.Moreover,it studies the operating conditions suitable for welding CNTs network anodes and successfully applies them to MFCs.This study has guiding significance for the development and application of high-efficiency MFCs anodes.