Electro-osmotic-based catholyte production by Microbial Fuel Cells for carbon capture.
In Microbial Fuel Cells (MFCs), the recovery of water can be achieved with the help of both active (electro-osmosis), and passive (osmosis) transport pathways of electrolyte through the semi-permeable selective separator. The electrical current-dependent transport, results in cations and electro-osmotically dragged water molecules reaching the cathode. The present study reports on the production of catholyte on the surface of the cathode, which was achieved as a direct result of electricity generation using MFCs fed with wastewater, and employing Pt-free carbon based cathode electrodes. The highest pH levels (>13) of produced liquid were achieved by the MFCs with the activated carbon cathodes producing the highest power (309 μW). Caustic catholyte formation is presented in the context of beneficial cathode flooding and transport mechanisms, in an attempt to understand the effects of active and passive diffusion. Active transport was dominant under closed circuit conditions and showed a linear correlation with power performance, whereas osmotic (passive) transport was governing the passive flux of liquid in open circuit conditions. Caustic catholyte was mineralised to a mixture of carbonate and bicarbonate salts (trona) thus demonstrating an active carbon capture mechanism as a result of the MFC energy-generating performance. Carbon capture would be valuable for establishing a carbon negative economy and environmental sustainability of the wastewater treatment process.
Bristol BioEnergy Centre, Bristol Robotics Laboratory, Block T, UWE, Coldharbour Lane, Bristol BS16 1QY, UK. Electronic address: iwona.gajda@brl.ac.uk.
Iwona
I
Gajda
Bristol BioEnergy Centre, Bristol Robotics Laboratory, Block T, UWE, Coldharbour Lane, Bristol BS16 1QY, UK; Biological, Biomedical and Analytical Sciences, UWE, Coldharbour Lane, Bristol BS16 1QY, UK.
John
J
Greenman
Bristol BioEnergy Centre, Bristol Robotics Laboratory, Block T, UWE, Coldharbour Lane, Bristol BS16 1QY, UK.
Chris
C
Melhuish
Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook rd, Storrs, CT 06269, USA; Center for Clean Energy Engineering, University of Connecticut, 44 Weaver rd, Storrs, CT 06269, USA; Center for Micro-Engineered Materials (CMEM), Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM, USA.
Carlo
C
Santoro
Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook rd, Storrs, CT 06269, USA; Center for Clean Energy Engineering, University of Connecticut, 44 Weaver rd, Storrs, CT 06269, USA.
Baikun
B
Li
RSE - Ricerca sul Sistema Energetico S.p.A., Environment and Sustainable Development Dept., Via Rubattino 54, 20134 Milan, Italy.
Pierangela
P
Cristiani
Bristol BioEnergy Centre, Bristol Robotics Laboratory, Block T, UWE, Coldharbour Lane, Bristol BS16 1QY, UK; Biological, Biomedical and Analytical Sciences, UWE, Coldharbour Lane, Bristol BS16 1QY, UK. Electronic address: ioannis.ieropoulos@brl.ac.uk.
Ioannis
I
Ieropoulos
D001639:Bicarbonates / Q000737:chemistry; D001674:Bioelectric Energy Sources; D002244:Carbon / Q000737:chemistry*; D004566:Electrodes; D004573:Electrolytes; D009995:Osmosis; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry; D014867:Water / Q000737:chemistry
D001639:Bicarbonates; D002244:Carbon; D004573:Electrolytes; D062065:Wastewater; D014867:Water; C029065:Magadi soda
Carbon capture; Carbon veil cathodes; Electro-osmotic drag; Microbial Fuel Cell (MFC); Oxygen reduction reaction