Journal
APPLIED SURFACE SCIENCE
Volume 467, Issue -, Pages 851-859Publisher
ELSEVIER
DOI: 10.1016/j.apsusc.2018.10.120
Keywords
Microbial fuel cell; Anode modification; Zeolite Y; Biofilm growth; Electrochemical characterization
Categories
Funding
- CONICYT (Chile) [CONICYT-PCHA/Doctorado Nacional/2015-211160606]
- FONDECYT [1140207]
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The performance of microbial fuel cells (MFCs) is highly dependent on the electrode materials. The electrode surface can be modified to provide a favorable environment for biofilms to enhance electron transfer from the bacteria to the anode. In this work, Faujasite zeolite-Y (ZY) was exchanged with iron (Fe) and was used to modify glassy carbon/graphite electrodes (GC/gr-ZY(Fe)) evaluating its effect in electroactive biofilm development for application in microbial fuel cells. The novel material was evaluated as an anode in MFCs by comparing its performance with GC/gr and GC/gr-ZY electrodes. The results show that when using a GC/gr-ZY(Fe) electrode, an electroactive biofilm with good electrochemical activity for acetate degradation can be generated on the electrode surface. The maximum current density obtained with a GC/gr-ZY(Fe)-BF electrode (where BF is biofilm) was 7.7 times higher than that of a GC/gr anode. The modification generates a less hydrophobic electrode surface that facilitates microbial cell attachment, thereby improving bioelectricity production. By using scanning electron microscopy, a homogeneous microbial community with bacteria that had a similar short rod-shaped morphology was observed. Furthermore, electrochemical impedance spectroscopy demonstrated that the charge transfer resistance (R-ct) decreased as the biofilm grew, revealing that the presence of the biofilm facilitated the electrochemical reaction. After 7 days of MFC operation, the GC/gr-ZY(Fe) bioanode showed a reduction in R-ct from 212.9 +/- 1.81 Omega to 151.5 +/- 1.46 Omega, which was 2.4 times lower than that achieved with GC/gr. The biofilm on GC/gr-ZY Fe was characterized using cyclic voltammetry, and the results showed a larger oxidation peak (169.8 mu A cm(-2)) than that of the GC/gr electrode (36.5 mu A cm(-2)), further supporting the better electron-transfer properties of the modified electrode. Additionally, this result confirms the capability of biofilms to act as bioelectrocatalysts under acetate-oxidizing conditions.
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