Early-stage performance evaluation of flowing microbial fuel cells using chemically treated carbon felt and yeast biocatalyst

The performance of closed-loop flowing-type microbial fuel cells using differently pretreated carbon felts is measured. Yeast cultivated from S. cerevisiae is used as biocatalyst, while glucose is the substrate. For the pretreatment of felt, acetone, nitric acid, and polyethyleneimine are employed. First the optimal conditions for yeast cultivation are quantitatively determined. As a result, a high yeast growth rate (1.083 h⁻¹) and the optimal yeast growing time (48 h) for cell tests are obtained. The differently pretreated felts are analyzed by X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy and optical microscopy. Conductivity, charge transfer resistance, and CdbndO and CsbndN groups dangled on the felt are crucial parameters determining the performance of the microbial fuel cell. Particularly, the conjugation effects of pi-pi bonds and lone pairs facilitating the attachment of yeast to the CdbndO and CsbndN groups on the carbon felt promote (i) mutual adhesion between them and (ii) growth of yeast on CF-PEI. This correlation is confirmed by optical analysis of the felts after the cell tests. To evaluate the early-stage performance of the microbial fuel cells using the different felts, polarization curves are measured. In the measurements, the maximum power density of the cells depends on the superficial state of felts, while the performance of the cell using the PEI-treated felt is best, at 256.3 ± 11.5 mW·m⁻². These data match other results attained by pretreatments.