Electrochemical Modification Research Of Anode Carbon Cloth For Single-chamber Microbial Fuel Cells

Microbial fuel cell (MFC) is a clean and renewable technology, which generateselectricity from degrading renewable biomass (sewage or other waste). The thesis is targetedfor treating domestic sewage in single-chamber air cathode microbial fuel cells (SCMFCs)with Pt/C cathode (Pt loading:0.5mg/cm2). Carbon cloth anodes were modified byelectrochemical oxidation in three electrolytes: nitric acid+sulfuric acid (CC-NS),ammonium nitrate (CC-AN), and ammonium sulfate (CC-AS). The surface biofilm andfunctional group on the modified anode were analyzed by scanning electron microscopy(SEM) and X-ray photoelectron spectrum (XPS). The basic mechanism of the electrochemicaloxidation method to improve the performance of SCMFCs was explored. Besides, the effectsof the anode modified methods (electrochemically and chemically-modified), acetateconcentration, ionic strength of solution and pH parameters on the SCMFC’s performancewere systematically studied.First, three kinds of electrolyte solutions (HNO3+H2SO4, NH4NO3,(NH4)2SO4,) havebeen utilized to modify anode carbon cloth. All the electricity production performances ofSCMFCs with modified anodes have been increased, the highest one is the anode modified bynitric acid and sulfuric acid.Second, the surface biofilm and functional group on the anode were characterized byscanning electron microscopy and X-ray photoelectron spectrum, which revealed the directreason of the electrochemical oxidation treatment to improve the performance of SCMFCs.The result underlined the positive effect of the surface modification on the SCMFCsperformance due to the increase in the amounts of unsaturated and oxidized carbon,Electrochemical Accessible Surface Area (ECSA) and bacterial attachment.Third, the impact of different treatment (electrochemically and chemically modified) onsurface morphology and elemental composition were analyzed. The SEM result shows thatcompared to chemically treated anode materials, electrochemical oxidation can enhance thesurface roughness, increase surface area and improve the surface etching with more grooves,thus facilitating the bacterium to accumulate on the anode surface. The XPS characterization showed that electrolysis process could produce more hydrophilic functional groups on theanode surface, and increase surface wettability. These changes could be the direct reason thatelectrolysis process improves SCMFC’s performance.Finally, based on the above research results, the CC-NS (HNO3+H2SO4) and CC-AN(NH4NO3) were applied as electrolyte to modify SCMFC’s anode carbon cloth in order todetermine the independent variable. The effects of substrate sodium acetate concentration,ionic strength, pH value and different concentration of mixed acid (nitric acid and sulfuricacid) were investigated. SCMFCs obtained the maximum output capacity with3g/L ofsodium acetate concentration,100mM of the sodium chloride concentration,8(CC-NS)/7.5(CC-AN) the pH value and1/6times as the concentrated acid for the mixed acid electrolyte.