Effect of Zeolite-Fe on graphite anode in electroactive biofilm development for application in microbial fuel cells.

Highlights • Glassy carbon electrode is modified with a dispersion of Y zeolite and graphite. • Zeolite changes the electrode surface hydrophobicity favoring the growth of a biofilm. • The modified anodes have an electroactive biofilm with electrochemical activity for acetate oxidation. • The presence of Fe species promotes electron transfer properties of anode. Abstract 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 Ω to 151.5 ± 1.46 Ω, 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 μA cm−2) than that of the GC/gr electrode (36.5μA 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. [ABSTRACT FROM AUTHOR]