title: A bipolar membrane combined with ferric iron reduction as an efficient cathode system in microbial fuel cells.
abstract: There is a need for alternative catalysts for oxygen reduction in the cathodic compartment of a microbial fuel cell (MFC). In this study, we show that a bipolar membrane combined with ferric iron reduction on a graphite electrode is an efficient cathode system in MFCs. A flat plate MFC with graphite felt electrodes, a volume of 1.2 L and a projected surface area of 290 cm2 was operated in continuous mode. Ferric iron was reduced to ferrous iron in the cathodic compartment according to Fe(3+) + e(-) --> Fe2+ (E0 = +0.77 V vs NHE, normal hydrogen electrode). This reversible electron transfer reaction considerably reduced the cathode overpotential. The low catholyte pH required to keep ferric iron soluble was maintained by using a bipolar membrane instead of the commonly used cation exchange membrane. For the MFC with cathodic ferric iron reduction, the maximum power density was 0.86 W/m2 at a current density of 4.5 A/m2. The Coulombic efficiency and energy recovery were 80-95% and 18-29% respectively.
authors.affiliation: Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
authors.forename: Annemiek
authors.initials: A
authors.lastname: Ter Heijne
authors.forename: Hubertus V M
authors.initials: HV
authors.lastname: Hamelers
authors.forename: Vinnie
authors.initials: V
authors.lastname: De Wilde
authors.forename: René A
authors.initials: RA
authors.lastname: Rozendal
authors.forename: Cees J N
authors.initials: CJ
authors.lastname: Buisman
mesh_terms: D001674:Bioelectric Energy Sources; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D010084:Oxidation-Reduction
chemical_list: D005290:Ferric Compounds; D008567:Membranes, Artificial