title: Graphite fiber brush anodes for increased power production in air-cathode microbial fuel cells.
abstract: To efficiently generate electricity using bacteria in microbial fuel cells (MFCs), highly conductive noncorrosive materials are needed that have a high specific surface area (surface area per volume) and an open structure to avoid biofouling. Graphite brush anodes, consisting of graphite fibers wound around a conductive, but noncorrosive metal core, were examined for power production in cube (C-MFC) and bottle (B-MFC) air-cathode MFCs. Power production in C-MFCs containing brush electrodes at 9600 m2/m3 reactor volume reached a maximum power density of 2400 mW/m2 (normalized to the cathode projected surface area), or 73 W/m3 based on liquid volume, with a maximum Coulombic efficiency (CE) of 60%. This power density, normalized by cathode projected area, is the highest value yet achieved by an air-cathode system. The increased power resulted from a reduction in internal resistance from 31 to 8 Q. Brush electrodes (4200 m2/m3) were also tested in B-MFCs, consisting of a laboratory media bottle modified to have a single side arm with a cathode clamped to its end. B-MFCs inoculated with wastewater produced up to 1430 mW/m2 (2.3 W/m3, CE = 23%) with brush electrodes, versus 600 mW/m2 with a plain carbon paper electrode. These findings show that brush anodes that have high surface areas and a porous structure can produce high power densities, and therefore have qualities that make them ideal for scaling up MFC systems.
authors.affiliation: Department of Civil and Environmental Engineering, The Penn State Hydrogen Energy (H2E) Center, Penn State University, University Park, Pennsylvania 16802, USA. blogan@psu.edu
authors.forename: Bruce
authors.initials: B
authors.lastname: Logan
authors.forename: Shaoan
authors.initials: S
authors.lastname: Cheng
authors.forename: Valerie
authors.initials: V
authors.lastname: Watson
authors.forename: Garett
authors.initials: G
authors.lastname: Estadt
mesh_terms: D000641:Ammonia / Q000737:chemistry; D001674:Bioelectric Energy Sources; D002244:Carbon / Q000737:chemistry; D000077482:Carbon Fiber; D004560:Electricity; D004566:Electrodes
chemical_list: D000077482:Carbon Fiber; D002244:Carbon; D000641:Ammonia