Impedance and Thermodynamic Analysis of Bioanode, Abiotic Anode, and Riboflavin-Amended Anode in Microbial Fuel Cells

Abstract

Department of Environmental Engineering, Sangmyung University, Cheonan 330-720, KoreaReceived June 28, 2012, Accepted July 17, 2012Understanding exoelectrogenic reactions of the bioanode is limited due to its complexity and the absence ofanalytics. Impedance and thermodynamics of bioanode, abiotic anode, and riboflavin-amended anode wereevaluated. Activation overpotential of the bioanode was negligible compared with that of the abiotic anode.Impedance spectroscopy shows that the bioanode had much lower charge transfer resistance and highercapacitance than the abiotic anode in low frequency reaction. In high frequency reaction, the impedanceparameters, however, were relatively similar between the bioanode and the abiotic anode. At open-circuitimpedance spectroscopy, a high frequency arc was not detected in the abiotic anode in Nyquist plot. Additionof riboflavin induced a phase angle shift and created curvature in high-frequency arc of the abiotic anode, andit also drastically changed impedance spectra of the bioanode.Key Words : Bioanode, Abiotic anode, Impedance, Anode biofilm, Microbial fuel cellIntroductionAnode biofilm is a crucial component in microbial fuelcells (MFCs) for electrogenesis. The main enzymatic com-ponents for electrogenesis of anode biofilm are exoelec-trogens, microorganisms that are capable of extracellularelectron transfer.