Date of Award

2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Abstract

Optimization of microbial fuel cells is investigated by utilizing Shewanella oneidensis as a model microorganism. the microbe's ability to grow and use glucose as a carbon source is explored under varying oxygen environments through an offline PMP derivatization method and HPLC analysis. Shewanella growth and glucose utilization is enhanced under aerobic environments; however, under microaerobic environments the addition of ferric iron results in a faster exponential growth initialization. a flavin mononucleotide modified indium tin oxide electrode is prepared and characterized for its usefulness in microbial fuel cells by controlled potential electrolysis, cyclic voltammetry, and electrochemical impedance spectroscopy studies. the electrode is shown to decrease impedance and charge transfer resistance when compared to a bare electrode. Additionally, the electron transfer mechanism is shown to be scan rate dependent. the addition of the monolayer decreased the contact angle resulting in a more hydrophilic surface for microbial attachment. the enhancement of electron transfer is explored through the poising of Shewanella on the modified electrode in the potential range of +0.6 to -0.6 V. Cyclic voltammetry studies performed immediately after poising results suggest catalytic election transfer occurs when Shewanella utilizes the FMN monolayer. Outer membrane protein reduction is absent in cyclic voltammetry following poising indicating direct electron transfer is blocked when the FMN monolayer is present. Current density is shown to increase as the poising potential becomes more negative with a maximum current achieved at -0.2 V. This increase in current density correlates to a decrease in impedance and charge transfer resistance with -0.2 V having the lowest overall initial impedance.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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