Effect of Congo Red on Electrochemical Characteristics of the Bioanode of Microbial Fuel Cell Explored for Simultaneous Azo Dye-containing Wastewater Treatment and Electricity Generation

To exploit the outstanding ability of microbial fuel cell (MFC) for simultaneous treatment of azo dye - polluted wastewater and bioelectricity generation, the effect of a representative azo dye - Congo red on the electrochemical characteristics of the bioanode of an air-cathode single chambered MFC was investigated in detail. The electrochemical impedance spectroscopy (EIS) showed that decolorization of different concentration of the Congo red had a negligible effect on the Ohmic resistance (Rohm) of the anode, but the charge-transfer resistance (Rc) and the diffusion resistance (Rd) were significantly influenced. The Rc and Rd firstly decreased then increased with increasing Congo red concentration, possibly due to the fact that Congo red can be served as electron shuttle for conveniently electrons transfer from bacteria to the anode at low concentration, but results in accelerated consumption of electrons at high concentration. The cathode impedance was totally not affected by the Congo red addition. cyclic voltammetry (CV) indicated that long-term decolorization of Congo red resulted in the change in the catalytic active site of the anode biofilm.