Cathode Assessment for Maximizing Current Generation in Microbial Fuel Cells Utilizing Bioethanol Effluent as Substrate

Abstract

Implementation of microbial fuel cells (MFCs) for electricity production requires effective current generation from waste products via robust cathode reduction. Three cathode types using dissolved oxygen cathodes (DOCs), ferricyanide cathodes (FeCs) and air cathodes (AiCs) were therefore assessed using bioethanol effluent, containing 20.5 g/L xylose, 1.8 g/L arabinose and 2.5 g/L propionic acid. In each set-up the anode and cathode had an electrode surface area of 88 cm 2 , which was used for calculation of the current density. Electricity generation was evaluated by quantifying current responses to substrate loading rates and external resistance. At the lowest external resistance of 27 Ω and highest substrate loading rate of 2 g chemical oxygen demand (COD) per L¨day, FeC-MFC generated highest average current density (1630 mA/m 2 ) followed by AiC-MFC (802 mA/m 2 ) and DOC-MFC (184 mA/m 2 ). Electrochemical impedance spectroscopy (EIS) was used to determine the impedance of the cathodes. It was thereby confirmed that the FeC-MFC produced the highest current density with the lowest internal resistance for the cathode. However, in a setup using bioethanol effluent, the AiC-MFC was concluded to be the most sustainable option since it does not require ferricyanide. The data offer a new add-on option to the straw biorefinery by using bioethanol effluent for microbial electricity production.

Novel Gas Diffusion Cloth Bioanodes for High-Performance Methane-Powered Microbial Fuel Cells

“…However, the cathodic polarization potential decreased slowly from +186 to +14 mV in this process. As suggested previously, the limiting electrode reaction could lead to a steep slope versus current in the polarization curve . Therefore, the steeper slope observed in the GDC anode polarization revealed that the electrogenic performance was mainly limited by anodic reactions rather than cathodic reactions.…”

“…As suggested previously, the limiting electrode reaction could lead to a steep slope versus current in the polarization curve. 34 Therefore, the steeper slope observed in the GDC anode polarization revealed that the electrogenic performance was mainly limited by anodic reactions rather than cathodic reactions. Linear regression analysis of the polarization curve for the entire cell gave a slope of −0.22 Ω• m 2 (i.e., −163.0 Ω) in the ohmic loss region.…”

Microbial fuel cell review: thermodynamic and infuencing factors, exoelectrogenic bacteria, anode and cathode configuration

“…It is possible to speed up the rate of oxygen reduction and hence greatly raise the current density produced by the MFC by coating the electrodes with a catalyst. 42 The most often used catalyst is platinum (Pt). Prathiba demonstrated that the current density may be increased by three times when Pt is added to the surface of the graphite cathode, as opposed to the straight graphite electrode.…”

“…According to a study by Chae et al, the type of simple compounds used resulted in very different faradaic yields (72.3% for acetate, 43.0% for butyrate, 36.0% for propionate and 15.0% for glucose), and these findings are related to the substrates' degree of fermentability. 121 Complex substrates Several natural effluents have been identified as suitable MFC substrates (domestic wastewater, 86 industrial effluents from food processing, 42 effluents from paper recycling plants, 122 animal manure 105 ). When complicated substrates are fed to MFCs, the faradaic efficiency and power produced are often substantially lower than those that can be attained with simple substrates.…”

Recent progress in microbial fuel cells using substrates from diverse sources

“…In terms of bioelectricity generation, acetate MFC gave the best performance with CD max of 20 A m −2 , PD max of 2 W m −2 , OCV max of 0.376 V, and CE of 12.6% [ 271 ]. Variations of the substrate concentrations and three different cathode conditions (dissolved oxygen, ferricyanide, and air cathodes) were used to evaluate the efficacy of current generation by waste products using a bioethanol effluent [ 272 ]. The results reported the highest substrate load of 2 g COD L −2 .…”