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.

Reference and counter electrode positions affect electrochemical characterization of bioanodes in different bioelectrochemical systems

“…For example, in the SEA configuration, the RE cannot fit in between the two electrodes due to a lack of sufficient space. The use of electrodes with different shapes such as rods, brushes, tubular, and flat plates (Logan et al, 2007;Rabaey et al, 2005) also affects the current distribution and thus the IR drop in the electrochemical tests. This IR drop may not only introduce errors in the measurements electrochemically, but also can result in biological changes in the bioanodes.…”

Optimizing the electrode size and arrangement in a microbial electrolysis cell

“…However, the application of the MEC technology to wastewater treatment requires further research to improve the design and develop inexpensive electrode materials with a high specific surface area, good conductivity, and a high stability. Several anode materials have been recently tested in MECs, including graphite granules, reticulate vitreous carbon, carbon foam, and graphite brush electrodes (Aelterman et al, 2006;Chaudhuri and Lovley, 2003;He et al, 2005;Logan et al, 2007;Zuo et al, 2007). The benefits of three dimensional (3D) anodes, which provide increased surface area for microbial attachment (Aelterman et al, 2008;Logan et al, 2007;Zhang et al, 2011), have been demonstrated by comparing a packed bed of irregular graphite granules with three different thicknesses to a one-dimensional configuration (Di Lorenzo et al, 2010).…”

“…Several anode materials have been recently tested in MECs, including graphite granules, reticulate vitreous carbon, carbon foam, and graphite brush electrodes (Aelterman et al, 2006;Chaudhuri and Lovley, 2003;He et al, 2005;Logan et al, 2007;Zuo et al, 2007). The benefits of three dimensional (3D) anodes, which provide increased surface area for microbial attachment (Aelterman et al, 2008;Logan et al, 2007;Zhang et al, 2011), have been demonstrated by comparing a packed bed of irregular graphite granules with three different thicknesses to a one-dimensional configuration (Di Lorenzo et al, 2010). Also, higher power outputs were observed in microbial fuel cells (MFCs) that have a 3D anode architecture (Chen et al, in press;Kim et al, 2011;Logan et al, 2007).…”

“…The benefits of three dimensional (3D) anodes, which provide increased surface area for microbial attachment (Aelterman et al, 2008;Logan et al, 2007;Zhang et al, 2011), have been demonstrated by comparing a packed bed of irregular graphite granules with three different thicknesses to a one-dimensional configuration (Di Lorenzo et al, 2010). Also, higher power outputs were observed in microbial fuel cells (MFCs) that have a 3D anode architecture (Chen et al, in press;Kim et al, 2011;Logan et al, 2007). However, the carbon source and proton transport limitations might limit the acceptable anode thickness (Sleutels et al, 2009;Torres et al, 2008), thus necessitating a more detailed study.…”

Application of 3D Printed Porous Copper Anode in Microbial Fuel Cells

“…Various materials and strategies have been utilized to improve MFC anode properties, including metal and non-metal materials with/without modification. (Rosenbaum et al, 2007;Rinaldi et al, 2008;Ghasemi et al, 2013) Carbon anodes [especially materials with high porosity and large surface area, such as carbon cloth (Yuan et al, 2010), carbon fiber brush (Logan et al, 2007;Wang et al, 2011;Wei et al, 2011), PPyCNTs (Zou et al, 2008), CNT/PANI (Nourbakhsh et al, 2017), graphene (Xie et al, 2012;Wang H. et al, 2013)] are widely used in MFCs due to their excellent stability and biocompatibility. However, 3D porous electrodes recently reported had either large (>500 µm) (Xie et al, 2011;Yong et al, 2012) or small (<10 µm) (He et al, 2012) pore sizes that could hardly be tuned.…”