Research On The Anode Of Microbial Fuel Cells Based On Nano-carbon Materials

As a new and challenging field,Microbial fuel cell(MFC)is a new environmental technology for wastewater treatment with simultaneous energy recovery in 21~stt century.In MFCs,chemical energy from organic pollutant can be directly converted into electrical energy by anodic exoelectrogenic bacteria,which aroused wide attention around the world.Although the MFCs electrode materials research has made a certain progress,scientists still have a lot of problems to discover and solve in microbial fuel cells,such as:low power output,high cost of production of MFC and the mechanism of MFC electricity production is not clear enough.In the whole process of using organic matter to generate electricity in MFCs,the dynamic activity of the anode limits the overall power current density.The transmission of electrons in the anode part plays a decisive role.The properties of the anode material directly influence whether the microorganism that generates electricity attaches to the anode quickly and transfer electrons to the anode smoothly.Therefore,the selection of excellent anode materials is of great significance for improving the power generation capacity of MFC.A necessary condition for anode material is high conductivity,non-corrosive,high specific surface area,high porosity,no dirt(i.e.,no bacteria filled),good biocompatibility,cheap and easy to manufacture and can be amplification.In this paper,we use two methods that two kinds of composite materials modify anode of microbial fuel cell to improve the electricity generation performance of microbial fuel cell.A method is that a non-metallic element nitrogen doped porous carbon materials modify carbon cloth as a microbial fuel cell anode,another method is that the metal elements doping carbon materials modify carbon cloth as a microbial fuel cell anode.To study the effect of modified anode material to electricity generation performance,and based on the isothermal adsorption method,scanning electron microscope and photoelectron spectroscopy analysis method to further explore reasons that the nonmetallic element and non-noble metal elements doping carbon materials modifiing anode respectively affect the electricity generation performance of MFCs.First,the research selected the two compounds(melamine and L-cysteine)as a nitrogen source,respectively,using one-step pyrolysis method to generate the two nitrogen-doped porous carbon materials used to modify carbon cloth as the anode electrode of MFC.The addition of nitrogen compounds makes the material form a porous structure with a large number of defect sites,and increasing the biocompatibility of anode electrodes of microbial fuel cell(MFCs).Under neutral conditions,two kinds of different compounds(melamine and L-cysteine)generated nitrogen doping porous carbon materials modified anode used in MFCs,obtain the maximum output power density of 2777.7 mW/m~2and 3523.1 mW/m~2.The second method:the research selected rice bran riching in metal atom(Ca,K,Mg and other elements)as the research object,by one-step pyrolysis to generate non-noble metal ions doped carbon materials,used to modify carbon cloth as the anode electrode of MFC.The experimental results show that:compared with general naked carbon cloth,the non-noble metal doped carbon materials modifiing carbon cloth used as anode in MFCs,obtain relatively high output power density,4485.9mW/m~2.After analysis,non-noble metal atom incorporation can improve the kinetic activity of anode materials.The slight differences in the content of non-precious metal elements have different effects on the electron transfer rate of the microbial anode,thus affecting the output power.