The Experts below are selected from a list of 11223 Experts worldwide ranked by ideXlab platform
Bruce E Logan - One of the best experts on this subject based on the ideXlab platform.
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impact of external Resistance acclimation on charge transfer and diffusion Resistance in bench scale microbial fuel cells
Bioresource Technology, 2020Co-Authors: Ruggero Rossi, Bruce E LoganAbstract:Abstract Reducing the external Resistance (Rext) for microbial fuel cell (MFC) acclimation can substantially alter the Anode performance in terms of charge transfer (RCT), diffusion (Rd) and total Anode Resistance (RAn). Electrochemical impedance spectroscopy (EIS) was used to quantify Anode impedance at different set potentials. Reducing Rext from 50 Ω to 20 Ω during acclimation reduced RCT by 31% (from 6.12 ± 0.09 mΩ m2 to 4.21 ± 0.03 mΩ m2) and Rd by 18% (from 3.4 ± 0.2 mΩ m2 to 2.8 ± 0.1 mΩ m2) at a set Anode potential of −115 mV during EIS. Overall RAn decreased by 27%, to 5.13 ± 0.02 mΩ m2 for acclimation at 20 Ω, enabling the Anode to achieve 38% higher current densities of 29 ± 1 A m−2. The results show a clear dependence of acclimation procedures and external Resistance on kinetic and diffusion components of Anode impedance that can impact overall bioelectrochemical performance.
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unraveling the contributions of internal Resistance components in two chamber microbial fuel cells using the electrode potential slope analysis
Electrochimica Acta, 2020Co-Authors: Ruggero Rossi, Bruce E LoganAbstract:Abstract Two-chamber (H-cell) bioelectrochemical systems (BESs) are one of the most widely used devices in bioelectrochemistry studies, but comparisons of performance have been challenged by differences in reactor architecture. Here we showed that the reactor solution Resistance should be calculated using only the tube cross-sectional area and length rather than the electrode spacing (i.e. the solution Resistance in the chambers is negligible). This approach was demonstrated using two H-cells (tube cross sectional areas of 4.5 cm2 or 1.2 cm2) and variable electrode areas. The solution Resistance (RΩ) calculated from the tube diameter and length was consistent with that measured using electrochemical impedance spectroscopy (EIS), and was ∼80% of the total internal Resistance with electrode areas larger than the tube area. Anode Resistance and total power were similar (RAn = 26 ± 1 Ω to RAn = 34 ± 1 Ω, 0.37 ± 0.00 mW) when the Anode was larger than the tube area (4.5 cm2), but the Resistance increased (RAn = 431 ± 229 Ω) when the Anode size (0.8 cm2) was smaller than the tube. Power and cathode Resistance changed more with the size of the cathode (RCat = 61 ± 5 Ω at 9.6 cm2, to RCat = 73 ± 7 Ω at 4.9 cm2), with very high Resistance when the cathode was smaller than the tube diameter (RCat = 1246 ± 805 Ω for 0.8 cm2 cathode). These results demonstrated that internal Resistances are relatively insensitive to electrode sizes when the electrodes are larger than the tube area. While it has not been common to report tube geometry in H-cell studies, these dimensions will need to be reported in future studies in order to make practical comparisons of performance among these types of reactors.
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applying the electrode potential slope method as a tool to quantitatively evaluate the performance of individual microbial electrolysis cell components
Bioresource Technology, 2019Co-Authors: Benjamin P Cario, Ruggero Rossi, Kyoungyeol Kim, Bruce E LoganAbstract:Improving the design of microbial electrolysis cells (MECs) requires better identification of the specific factors that limit performance. The contributions of the electrodes, solution, and membrane to internal Resistance were quantified here using the newly-developed electrode potential slope (EPS) method. The largest portion of total internal Resistance (120 ± 0 mΩ m2) was associated with the carbon felt Anode (71 ± 5 mΩ m2, 59% of total), likely due to substrate and ion mass transfer limitations arising from stagnant fluid conditions and placement of the electrode against the anion exchange membrane. The Anode Resistance was followed by the solution (25 mΩ m2) and cathode (18 ± 2 mΩ m2) Resistances, and a negligible membrane Resistance. Wide adoption and application of the EPS method will enable direct comparison between the performance of the components of MECs with different solution characteristics, electrode size and spacing, reactor architecture, and operating conditions.
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reference and counter electrode positions affect electrochemical characterization of bioAnodes in different bioelectrochemical systems
Biotechnology and Bioengineering, 2014Co-Authors: Fang Zhang, Ivan Ivanov, Marta C Hatzell, Wulin Yang, Bruce E LoganAbstract:The placement of the reference electrode (RE) in various bioelectrochemical systems is often varied to accommodate different reactor configurations. While the effect of the RE placement is well understood from a strictly electrochemistry perspective, there are impacts on exoelec- trogenic biofilms in engineered systems that have not been adequately addressed. Varying distances between the working electrode (WE) and the RE, or the RE and the counter electrode (CE) in microbial fuel cells (MFCs) can alter bioAnode characteristics. With well-spaced Anode and cathodedistancesinanMFC,increasingthedistancebetween the RE and Anode (WE) altered bioAnode cyclic voltammo- grams (CVs) due to the uncompensated ohmic drop. Electrochemical impedance spectra (EIS) also changed with RE distances, resulting in a calculated increase in Anode Resistance that varied between 17 and 31V (� 0.2V). While WE potentials could be corrected with ohmic drop compensation during the CV tests, they could not be automatically corrected by the potentiostat in the EIS tests. The electrochemical characteristics of bioAnodes were altered by their acclimation to different Anode potentials that resulted from varying the distance between the RE and the CE (cathode). These differences were true changes in biofilm characteristics because the CVs were electrochemically independent of conditions resulting from changing CE to RE distances. Placing the RE outside of the current path enabled accurate bioAnode characterization using CVs and EIS due to negligible ohmic Resistances (0.4V). It is therefore concludedforbioelectrochemicalsystemsthatwhenpossible, theREshouldbeplacedoutside thecurrent pathandnear the WE, as this will result in more accurate representation of bioAnode characteristics. Biotechnol. Bioeng. 2014;111: 1931-1939.
Ruggero Rossi - One of the best experts on this subject based on the ideXlab platform.
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impact of external Resistance acclimation on charge transfer and diffusion Resistance in bench scale microbial fuel cells
Bioresource Technology, 2020Co-Authors: Ruggero Rossi, Bruce E LoganAbstract:Abstract Reducing the external Resistance (Rext) for microbial fuel cell (MFC) acclimation can substantially alter the Anode performance in terms of charge transfer (RCT), diffusion (Rd) and total Anode Resistance (RAn). Electrochemical impedance spectroscopy (EIS) was used to quantify Anode impedance at different set potentials. Reducing Rext from 50 Ω to 20 Ω during acclimation reduced RCT by 31% (from 6.12 ± 0.09 mΩ m2 to 4.21 ± 0.03 mΩ m2) and Rd by 18% (from 3.4 ± 0.2 mΩ m2 to 2.8 ± 0.1 mΩ m2) at a set Anode potential of −115 mV during EIS. Overall RAn decreased by 27%, to 5.13 ± 0.02 mΩ m2 for acclimation at 20 Ω, enabling the Anode to achieve 38% higher current densities of 29 ± 1 A m−2. The results show a clear dependence of acclimation procedures and external Resistance on kinetic and diffusion components of Anode impedance that can impact overall bioelectrochemical performance.
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unraveling the contributions of internal Resistance components in two chamber microbial fuel cells using the electrode potential slope analysis
Electrochimica Acta, 2020Co-Authors: Ruggero Rossi, Bruce E LoganAbstract:Abstract Two-chamber (H-cell) bioelectrochemical systems (BESs) are one of the most widely used devices in bioelectrochemistry studies, but comparisons of performance have been challenged by differences in reactor architecture. Here we showed that the reactor solution Resistance should be calculated using only the tube cross-sectional area and length rather than the electrode spacing (i.e. the solution Resistance in the chambers is negligible). This approach was demonstrated using two H-cells (tube cross sectional areas of 4.5 cm2 or 1.2 cm2) and variable electrode areas. The solution Resistance (RΩ) calculated from the tube diameter and length was consistent with that measured using electrochemical impedance spectroscopy (EIS), and was ∼80% of the total internal Resistance with electrode areas larger than the tube area. Anode Resistance and total power were similar (RAn = 26 ± 1 Ω to RAn = 34 ± 1 Ω, 0.37 ± 0.00 mW) when the Anode was larger than the tube area (4.5 cm2), but the Resistance increased (RAn = 431 ± 229 Ω) when the Anode size (0.8 cm2) was smaller than the tube. Power and cathode Resistance changed more with the size of the cathode (RCat = 61 ± 5 Ω at 9.6 cm2, to RCat = 73 ± 7 Ω at 4.9 cm2), with very high Resistance when the cathode was smaller than the tube diameter (RCat = 1246 ± 805 Ω for 0.8 cm2 cathode). These results demonstrated that internal Resistances are relatively insensitive to electrode sizes when the electrodes are larger than the tube area. While it has not been common to report tube geometry in H-cell studies, these dimensions will need to be reported in future studies in order to make practical comparisons of performance among these types of reactors.
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applying the electrode potential slope method as a tool to quantitatively evaluate the performance of individual microbial electrolysis cell components
Bioresource Technology, 2019Co-Authors: Benjamin P Cario, Ruggero Rossi, Kyoungyeol Kim, Bruce E LoganAbstract:Improving the design of microbial electrolysis cells (MECs) requires better identification of the specific factors that limit performance. The contributions of the electrodes, solution, and membrane to internal Resistance were quantified here using the newly-developed electrode potential slope (EPS) method. The largest portion of total internal Resistance (120 ± 0 mΩ m2) was associated with the carbon felt Anode (71 ± 5 mΩ m2, 59% of total), likely due to substrate and ion mass transfer limitations arising from stagnant fluid conditions and placement of the electrode against the anion exchange membrane. The Anode Resistance was followed by the solution (25 mΩ m2) and cathode (18 ± 2 mΩ m2) Resistances, and a negligible membrane Resistance. Wide adoption and application of the EPS method will enable direct comparison between the performance of the components of MECs with different solution characteristics, electrode size and spacing, reactor architecture, and operating conditions.
Cees J N Buisman - One of the best experts on this subject based on the ideXlab platform.
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performance of a scaled up microbial fuel cell with iron reduction as the cathode reaction
Journal of Power Sources, 2011Co-Authors: Annemiek Ter Heijne, Hubertus V M Hamelers, Fei Liu, Lucas S Van Rijnsoever, Michel Saakes, Cees J N BuismanAbstract:Scale-up studies of Microbial Fuel Cells are required before practical application comes into sight. We studied an MFC with a surface area of 0.5 m2 and a volume of 5 L. Ferric iron (Fe3+) was used as the electron acceptor to improve cathode performance. MFC performance increased in time as a combined result of microbial growth at the bio-Anode, increase in iron concentration from 1 g L-1 to 6 g L-1, and increased activity of the iron oxidizers to regenerate ferric iron. Finally, a power density of 2.0 W m-2 (200 W m-3) was obtained. Analysis of internal Resistances showed that Anode Resistance decreased from 109 to 7 mO m2, while cathode Resistance decreased from 939 to 85 mO m2. The cathode was the main limiting factor, contributing to 58% of the total internal Resistance. Maximum energy efficiency of the MFC was 41%.
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effect of mass and charge transport speed and direction in porous Anodes on microbial electrolysis cell performance
Bioresource Technology, 2011Co-Authors: Tom H J A Sleutels, Hubertus V M Hamelers, Cees J N BuismanAbstract:The use of porous electrodes like graphite felt as Anode material has the potential of achieving high volumetric current densities. High volumetric current densities, however, may also lead to mass transport limitations within these porous materials. Therefore, in this study we investigated the mass and charge transport limitations by increasing the speed of the forced flow and changing the flow direction through the porous Anode. Increase of the flow speed led to a decrease in current density when the flow was directed towards the membrane caused by an increase in Anode Resistance. Current density increased at higher flow speed when the flow was directed away from the membrane. This was caused by a decrease in transport Resistance of ions through the membrane which increased the buffering effect of the system. Furthermore, the increase in flow speed led to an increase of the coulombic efficiency by 306%.
Hubertus V M Hamelers - One of the best experts on this subject based on the ideXlab platform.
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performance of a scaled up microbial fuel cell with iron reduction as the cathode reaction
Journal of Power Sources, 2011Co-Authors: Annemiek Ter Heijne, Hubertus V M Hamelers, Fei Liu, Lucas S Van Rijnsoever, Michel Saakes, Cees J N BuismanAbstract:Scale-up studies of Microbial Fuel Cells are required before practical application comes into sight. We studied an MFC with a surface area of 0.5 m2 and a volume of 5 L. Ferric iron (Fe3+) was used as the electron acceptor to improve cathode performance. MFC performance increased in time as a combined result of microbial growth at the bio-Anode, increase in iron concentration from 1 g L-1 to 6 g L-1, and increased activity of the iron oxidizers to regenerate ferric iron. Finally, a power density of 2.0 W m-2 (200 W m-3) was obtained. Analysis of internal Resistances showed that Anode Resistance decreased from 109 to 7 mO m2, while cathode Resistance decreased from 939 to 85 mO m2. The cathode was the main limiting factor, contributing to 58% of the total internal Resistance. Maximum energy efficiency of the MFC was 41%.
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effect of mass and charge transport speed and direction in porous Anodes on microbial electrolysis cell performance
Bioresource Technology, 2011Co-Authors: Tom H J A Sleutels, Hubertus V M Hamelers, Cees J N BuismanAbstract:The use of porous electrodes like graphite felt as Anode material has the potential of achieving high volumetric current densities. High volumetric current densities, however, may also lead to mass transport limitations within these porous materials. Therefore, in this study we investigated the mass and charge transport limitations by increasing the speed of the forced flow and changing the flow direction through the porous Anode. Increase of the flow speed led to a decrease in current density when the flow was directed towards the membrane caused by an increase in Anode Resistance. Current density increased at higher flow speed when the flow was directed away from the membrane. This was caused by a decrease in transport Resistance of ions through the membrane which increased the buffering effect of the system. Furthermore, the increase in flow speed led to an increase of the coulombic efficiency by 306%.
Benjamin P Cario - One of the best experts on this subject based on the ideXlab platform.
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applying the electrode potential slope method as a tool to quantitatively evaluate the performance of individual microbial electrolysis cell components
Bioresource Technology, 2019Co-Authors: Benjamin P Cario, Ruggero Rossi, Kyoungyeol Kim, Bruce E LoganAbstract:Improving the design of microbial electrolysis cells (MECs) requires better identification of the specific factors that limit performance. The contributions of the electrodes, solution, and membrane to internal Resistance were quantified here using the newly-developed electrode potential slope (EPS) method. The largest portion of total internal Resistance (120 ± 0 mΩ m2) was associated with the carbon felt Anode (71 ± 5 mΩ m2, 59% of total), likely due to substrate and ion mass transfer limitations arising from stagnant fluid conditions and placement of the electrode against the anion exchange membrane. The Anode Resistance was followed by the solution (25 mΩ m2) and cathode (18 ± 2 mΩ m2) Resistances, and a negligible membrane Resistance. Wide adoption and application of the EPS method will enable direct comparison between the performance of the components of MECs with different solution characteristics, electrode size and spacing, reactor architecture, and operating conditions.