title: Cathodic and anodic biofilms in Single Chamber Microbial Fuel Cells.
abstract: The oxygen reduction due to microaerophilic biofilms grown on graphite cathodes (biocathodes) in Single Chamber Microbial Fuel Cells (SCMFCs) is proved and analysed in this paper. Pt-free cathode performances are compared with those of different platinum-loaded cathodes, before and after the biofilm growth. Membraneless SCMFCs were operating in batch-mode, filled with wastewater. A substrate (fuel) of sodium acetate (0.03 M) was periodically added and the experiment lasted more than six months. A maximum of power densities, up to 0.5 W m(-2), were reached when biofilms developed on the electrodes and the cathodic potential decreased (open circuit potential of 50-200 mV vs. SHE). The power output was almost constant with an acetate concentration of 0.01-0.05 M and it fell down when the pH of the media exceeded 9.5, independently of the Pt-free/Pt-loading at the cathodes. Current densities varied in the range of 1-5 Am(-2) (cathode area of 5 cm(2)). Quasi-stationary polarization curves performed with a three-electrode configuration on cathodic and anodic electrodes showed that the anodic overpotential, more than the cathodic one, may limit the current density in the SCMFCs for a long-term operation.
authors.affiliation: RSE - Ricerca sul Sistema Elettrico S.p.A., Environment and Sustainable Development Department, Via Rubattino 54, 20134 Milan, Italy. pierangela.cristiani@rse-web.it
authors.forename: P
authors.initials: P
authors.lastname: Cristiani
authors.forename: M L
authors.initials: ML
authors.lastname: Carvalho
authors.forename: E
authors.initials: E
authors.lastname: Guerrini
authors.forename: M
authors.initials: M
authors.lastname: Daghio
authors.forename: C
authors.initials: C
authors.lastname: Santoro
authors.forename: B
authors.initials: B
authors.lastname: Li
mesh_terms: D000332:Aerobiosis; D001674:Bioelectric Energy Sources; D018441:Biofilms / Q000254:growth & development*; D057919:Biological Oxygen Demand Analysis; D002119:Calcium Carbonate / Q000737:chemistry; D004553:Electric Conductivity; D055664:Electrochemical Techniques; D004566:Electrodes / Q000382:microbiology; D004867:Equipment Design; D006108:Graphite / Q000737:chemistry; D017404:In Situ Hybridization, Fluorescence; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D016999:Sulfur-Reducing Bacteria / Q000254:growth & development; D062065:Wastewater / Q000737:chemistry
chemical_list: D002119:Calcium Carbonate; D006108:Graphite; D010100:Oxygen; D010984:Platinum; D062065:Wastewater