Fabrication Of Phenolic Resin-based Three-dimensional Porous Carbon Material And Their Electricity Generation Performance Study As Microbial Anode

Microbial fuel cells（MFCs）can convert organic matter into electrical energy in wastewater,have the advantages of environmental,efficient and mild operating conditions.MFCs can be combined with a variety of traditional water treatment methods and has a potential application prospect in wastewater treatment.However,compared with traditional fuel cells,MFCs still suffer from low productivity and poor stability,which limits their practical application.Anode as accommodation of the microorganisms,affects the biofilm formation and electron transfer process from electrogenerative microorganisms to anode,thus in a large part determining the electricity generation performance of MFCs.Traditional anode materials with small surface area and high resistance limiting the electron transport.Phenolic resin based porous carbon material is an ideal anode material for MFCs,because of its low cost,high stabilization and modifiability.Therefore,in this paper,phenolic resin is used as carbon source to prepare three-dimensional carbon-based anode materials.By using high temperature carbonization method,and adding PVP（polyvinylpyrrolidone）or polymethyl methacrylate microspheres as pore structure-guiding agent.Then their performance as MFCs anodes was studied.The research content of this paper is as follows:The nitrogen doped three-dimensional porous carbon anode material（NPVP-RFC）was prepared using phenolic resin as carbon source,Dicyandiamide as nitrogen source and PVP as pore-forming agent.Compared with N-RFC without pore-forming agent and commercial carbon cloth,the introduction of PVP significantly reduced the electrical impedance of NPVP-RFC and significantly enhanced the specific surface.The structure of the material with rough and porous surface was confirmed by scanning electron microscope.NPVP-RFC-equipped MFC exhibited higher voltage and power density,and its start-up time was significantly shortened.The advantages of NPVP-RFC about enrichment of electrogenerative microorganisms further verified by scanning electron microscopy,laser confocal and gene sequencing.The materials with different pore size were synthesized by using polymethyl methacrylate microspheres of 5.75μm and 4.38μm as template,which were denoted as 3D-OMC-5.75,3D-OMC-4.38.A series of characterization analysis confirmed that these anodes have interconnected,ordered porous structures.The electrochemical impedance and cyclic voltammogram curves show that the resistance of the three-dimensional ordered porous anode is smaller and the electrochemical activity is higher.The three-dimensional ordered porous carbon materials with different pore size are use as anode of microbial fuel cell.The MFCs exhibited faster start-up speed,higher output voltage and power density,higher COD removal rate and coulombic efficiency.The 3D-OMC-5.75 anode demonstrated the better performance of electricity generation and COD removal rate,which can be explained from the growth and distribution of anode biofilms,the abundance and electroactivity of electrogenerative microorganisms.The operation time of 3D-OMC-5.75 anode is nearly 800 days and shows excellent long-term operating stability.Dicyandiamide as nitrogen source was added into phenolic resin to prepare three-dimensional ordered porous carbon materials with different nitrogen content.The inputs of nitrogen source are 0.2 g/10 m L,0.4 g/10 m L,0.6 g/10 m L respectively for3D-NOMC-0.2,3D-NOMC-0.4,3D-NOMC-0.6.The hydrophilic properties and electrical conductivity of the three-dimensional ordered porous carbon materials were improved.The MFCs equipped with 3D-NOMCs achieved faster startup,higher voltage output,higher power density,higher COD removal rate and coulombic efficiency.The 3D-NOMC-0.4 anode shows highest performance in terms of electricity generation performance and COD removal rate.The growth and distribution of anode biofilm,the abundance and electroactivity of electrogenerative microorganisms,combined with theoretical calculation were further studied to explain the higher performance of 3D-NOMC-0.4 anode.3D-NOMC-0.4 anode show the higher artificial wastewater removal performance.And its size was expanded from 1 cm to 2.15 cm,obtained the expanded nitrogen-doped phenolic resin based three-dimensional ordered porous carbon（sc-3DNOMC-0.4）.The sc-3DNOMC-0.4 as an MFC anode for the treatment of high concentration organic wastewater,it shows high performance.sc-3DNOMC-0.4 anode showed faster start-up speed and higher power output in artificial wastewater.When the substrate was changed to high concentration organic wastewater,sc-3DNOMC-0.4 anode also showed high performance,achieve a maximum voltage of 0.72 V and a power density of 2.87 W·m^-2,and the possible reason for its high electrical performance was explained from a biological perspective.