2EU-ISMET, Alessandro Carmona
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2EU-ISMET, Alessandro Carmona
- 1. On the modeling of the surface area that actually contributes to the current density produced in microbial electrochemical systems Alessandro Carmona1, Rémy Lacroix2, Serge Da Silva2, Eric Trably1 and Nicolas Bernet1 1INRA, Laboratoire de Biotechnologie de l’Environnement, Narbonne, France, alessandro.carmona@supagro.inra.fr; 26T-MIC Ingénieries, Toulouse, France
- 2. Context
- 3. Overall view of bioelectrochemical systems Configuration of a BES: membrane specificity, type of catalysts at both electrodes, and the source of the reducing power Harnisch, F. et al., ChemSusChem. 2009; Franks, A.E. et al., Biofuels. 2010; Logan, B.E. et al., Environ. Sci. Technol. 2008 or or Anode Power supply Renewable energy Cathode C+ A-e- e- Catalysts at the Anode Microbially catalysed CO2 O2 H2O H+ Membrane specificity Rabaey, K. et al, Nat. Rev. Micro. 2010. 8(10): p. 706-716 Catalysts at the Cathode Product „electrochemical device that exploits living Product microbial cells for the bioelectrocatalysis of anodic-oxidation and/or cathodic-reduction reactions“ Harnisch F. et al. Chem. Asian J. 2012, 7, 466 – 475 e- Organics Chemially or catalysed H2 e- Electron acceptor Microbially catalysed Chemially catalysed or Electron acceptor C+ A-A-C+ C+ A-or or cation anion no membrane exchange membrane Power production Short circuit e- e-e-e- e-e- e- Reducing power
- 4. Experimental approach in METS Operational parameters Electrochemistry CA, CV, EIS… Reactor design Microscopy Fingerprinting SEM, CLSM.. 16S rRNA Harnisch and Rabaey, ChemSusChem. 2012 pH T° OLR CE% HRT
- 5. Electrodes in bioelectrochemical systems Carbon paper Graphite plate Carbon mesh Granular graphite Polycrystalline Carbon rod Carbon brush Carbon felt Reticulated vitrified carbon graphite Photographs taken from: Wei J. et al. Bioresour. Technol. 2011. 102: p. 9335–9344
- 6. Current density in microbial BESs Modified from: Schröder, U., J. Solid State Electrochem. 2011 Chen, S. et al., Energy Environ Sci. 2012 Chen, S. et al., Energy Environ Sci. 2011 Zhao, Y. et al., Chem. Eur. J. 2010,
- 7. What surface should be used to calculate current? in BESs!!! “Flat stainless steel has produced up to 20 A/m2…” “these data must be qualified because the 2 sides of the electrode were exposed to the (medium) solution while the current density was calculated with respect to 1 side only” Rimboud, M., Physical Chemistry Chemical Physics. 2014 e- e- e- e- “An example of poor design would be a cell with a plate working electrode with both sides active and a counter electrode facing only one surface” Drawn from: Pletcher, D., Royal society of chemistry. 2009 Potential distribution in mV at the surface of a ring-shaped WE using an 120 mV “The varying iR drops along the different current paths produce a nonuniform potential across the WE’s surface, and as a consequence there is a nonuniform current density on the WE’s surface. These effects can cause undesired side reactions or ineffective use of the total electrode area” Drawn from: Bard, A., Wiley. 2001 WE CE 125 33 25 75 45 85 63 95 113 unsymetrical CE Insulated Insulated mV mV Anode Cathode Reference electrode e.g., vs. Ag/AgCl
- 8. Experimental approach Cronoamperometry Cyclic voltammetry CLSM COMSOL* current production distribution, electron transfer and biofilm formation/structure “COMSOL Multiphysics is an engineering simulation software that facilitates all steps of a computational modeling process; such as defining the geometry, surface meshing, specifying the physics, solving, and then visualizing the results” Dalak, E., M.Sc. Thesis. 2012 Do both sides of a planar electrode material contribute to electron transfer?
- 10. Anode-respiring bacterium model Nanowire? NADH NAD+ NAD+ 2CO2 Geoalkalibacter subterraneus Electrons 8H+ Electrode Cytochrome pool? e- 8 e- 2H2O CH3COOH turnover Ef -365 mV Geoalkalibacter cell (5-6 μm) 0.0 -0.5 -1.0 Potential vs. SCE (V) at pH 7 non turnover Ef -428 mV CLSM confirmed a thick biofilm composed of several layers of metabolically active bacteria all over the electrode Electrons e- Conductive filaments? Electrode Single bacterial cells Biofilm thickness :76 μm Cyclic voltammetry indicates an direct electron transfer mechanism via a conduit with a defined formal potential window Geoalkalibacter subterraneus Biofilm on both sides
- 11. SCE as RE Temperature controlled system at 37°C Continuos stirring at 200 rpm Experimental conditions Data based on at least 2 independent biofilm replicates B. E. Logan, ChemSusChem, 2012, 5, 988-994 RE CE WE1 WE2 Insulator Insulator Active→│←Inactive Active→│←Inactive DSMZ culture 48 h 3000 Liquid culture rpm Half cell Graphite plate as Working electrode Pt grid as Counter electrode WE1 WE2 Top view Non conductive Non conductive Biofilm Biofilm Potentiostatic controlled half-cell: -Similar biological-environmental conditions for both electrodes -High reproducibility by maintaining one of the electrodes at a constant potential vs. reference electrode LaBelle,E. et al. Bioelectrochemical Systems. 2010
- 13. Chronoamperometric formation of Geoalkalibacter biofilms WE1 WE2 Biofilm on both electrodes RE CE WE1 WE2 Insulator Insulator Non conductive Non conductive Biofilm Biofilm Active→│←Inactive Active→│←Inactive
- 14. Turnover cyclic voltammetry Independent replicate Exp. at 5.00 S/m Exp. at 1.00 S/m jmax decreases jmax Ef: -470 mv
- 15. Biofilm imaging using CLSM, PHLIP analysis… Franks, A. et al. ChemSusChem (2012) …and COMSOL WE2 Thickness: 75 μm (± 7) Current: 2.60 A/m2 (± 0.01) WE1 Thickness: 71 μm (± 12) Current: 2.57 A/m2 (± 0.07) 3 2 1 0 3 2 1 0 j/ A m-2 j/ A m-2 Active→│←Inactive CE Active→│←Inactive WE1 WE2 current distribution by COMSOL
- 16. Conclusion Cronoamperometry Cyclic voltammetry CLSM COMSOL current production distribution, electron transfer and biofilm formation/structure WE j / A m-2 Ef/ mV Thickness/ μm j distribution 1 2.6 -475 71 uniform 2 2.5 -476 75 uniform Both sides of a planar electrode material do contribute to current production regardless the electrode side orientation
- 17. Pitch sessions S2-6, Poster PP-13, Today from 16 h, Room 1.7
- 18. Rémy Serge Eric Nicolas
Editor's Notes
- In BESs, a plenitude of possible applications can be found (Fig. 1-6), from the original and promising production of electricity (Logan, et al., 2006), to hydrogen as a clean fuel (Logan, et al., 2008) and the production of useful chemicals (Rabaey and Rozendal, 2010) such as hydrogen peroxide, extraordinarily from wastewater (Fu, et al., 2010, You , et al., 2010). Nonetheless, the cited applications in this section would not be possible without the basic research on the microbe-electrode interactions which inexorably turn out to contribute to the betterment of the overall performance of this kind of systems by eliminating (or at least diminishing) electrochemical losses of BESs (Schröder and Harnisch, 2010). Therefore, the analysis of the microbe-electrode interactions would lead not only to a higher comprehension on improving the overall performance of BESs (see section 1.5) from the power production point of view but also on improving a more precise electron uptake by microorganisms for the production of useful and industrial demanded biochemicals (Nevin, et al., 2010, Ross, et al., 2011). As shown in Fig. 1-6, microbial-electrode interactions can take place in both electrode chambers depending on the application for which the BES has been designed. A simplified version of a BES system as shown in the insert of Fig. 1-6 is a potentiostatic controlled electrochemical half-cell in which an anode and a cathode are hosted within one vessel (LaBelle, et al., 2010). This experimental approach assures similar biological and environmental conditions for both electrodes and increases the reproducibility of the experiment by maintaining one of the electrodes at a constant potential permanently controlled against a reference electrode (e.g., vs. Ag/AgCl) (Bard, et al., 2008). This type of BES (with multiple modifications) is the one that has been extensively used in this Thesis.
- Sad bacteria: http://www.clipartof.com/gallery/clipart/germ.html
- As one can see from the literature (Schröder, 2011), one of the motivations for the development of the BES technology has been a competitive “race” to increase the current production and trying to make this technology an affordable option for the treatment of wastewater with the concomitant consequence production of sustainable electricity and biochemicals (Rabaey and Rozendal, 2010). Here, the understanding of microbial-electrode interactions has been part of the global effort to accomplish BESs with an enhanced performance. Current density based on available anode surface area has made a noticeable development (Fig 1-7). Since 1999, the experimental biotransformation of substrate (fuel) to electric energy (Schröder, 2007) has been performed with the utilization of dissimilatory metal reducing bacteria (e.g., from the Shewanellaceae family (Kim, et al., 1999b, Kim, et al., 1999d)). The performance of the current density production has seen a considerable increment from only 0.013 μA cm-2 (Kim, et al., 1999d) to more than 30 A m-2 (see Chapter 5 and 6). The betterment of performance of BESs based on the current density is (among other factors) due to: i. the fabrication of porous three dimensional materials that allow bacteria to take advantage of higher electrode surface areas to release electrons (Katuri, et al., 2011, Šefčovičová, et al., 2011, Xie, et al., 2011, Yu, et al., 2011) (see Chapter 5 and 6); ii. the comprehension of how electrochemically active bacteria associate with some electrode materials through improved anode enrichment processes (Kim, et al., 2004, Liu, et al., 2008, Rabaey, et al., 2004); and iii. through the study of the process of biofilm formation influenced by environmental factors (see Chapter 7 and 8).
- As one can see from the literature (Schröder, 2011), one of the motivations for the development of the BES technology has been a competitive “race” to increase the current production and trying to make this technology an affordable option for the treatment of wastewater with the concomitant consequence production of sustainable electricity and biochemicals (Rabaey and Rozendal, 2010). Here, the understanding of microbial-electrode interactions has been part of the global effort to accomplish BESs with an enhanced performance. Current density based on available anode surface area has made a noticeable development (Fig 1-7). Since 1999, the experimental biotransformation of substrate (fuel) to electric energy (Schröder, 2007) has been performed with the utilization of dissimilatory metal reducing bacteria (e.g., from the Shewanellaceae family (Kim, et al., 1999b, Kim, et al., 1999d)). The performance of the current density production has seen a considerable increment from only 0.013 μA cm-2 (Kim, et al., 1999d) to more than 30 A m-2 (see Chapter 5 and 6). The betterment of performance of BESs based on the current density is (among other factors) due to: i. the fabrication of porous three dimensional materials that allow bacteria to take advantage of higher electrode surface areas to release electrons (Katuri, et al., 2011, Šefčovičová, et al., 2011, Xie, et al., 2011, Yu, et al., 2011) (see Chapter 5 and 6); ii. the comprehension of how electrochemically active bacteria associate with some electrode materials through improved anode enrichment processes (Kim, et al., 2004, Liu, et al., 2008, Rabaey, et al., 2004); and iii. through the study of the process of biofilm formation influenced by environmental factors (see Chapter 7 and 8).
- Sad bacteria: http://www.clipartof.com/gallery/clipart/germ.html
- How can we go from the concept of a normal microorganism to a so called Electrochemically active bacteria? -In the environment electrochemically active bacteria (EAB) can transfer electrons to solid terminal electron acceptors such as Fe(III), Mn(III) or Cr(VI). -In a Bioelectrochemical system such as microbial fuel cells (MFCs) these bacteria transfer the electrons to carbon materials for example. These bacteria not only play a key role in nature’s oxidation-reduction cycles but also are the key component of microbial bioelectrochemical systems (BES). Thus, the elucidation of the different microbial electron transfer pathways is of fundamental interest as well as technological relevance. For the family of Shewanellaceae – all being considered to be facultative anaerobes - several members have been studied on their extra-cellular electron transfer behavior. Most prominently S. oneidensis MR-1 was widely studied, e.g.: [28-31], but also S. putrefaciens [32-37], S. loihica [32, 38-41], S. decolorationis [42, 43], S. japonica [44], S. frigidimarina [45, 46] and S. marisflavi [47]. Commonly, it is assumed that the two decaheme c-type cytochromes MtrC and OmcA, both facing the extracellular environment, play a key role in the direct electron transfer mechanism (DET) [28, 48-52]. Thereby, MtrC and OmcA, are part of a complex transmembrane cytochrome pool involving more than 40 proteins [53]. The MET of Shewanellaceae usually exploits flavins, like riboflavin [54] and flavinmononucleotide (FMN) [44, 55] and their derivatives, and is considered to depend on intracellular electron transfer to the redox-shuttle as well as extracellular electron transfer by MtrC or OmcA, e.g. [44, 56, 57]. Thereby it has been shown that some strains of Shewanella family (e.g. S. oneidenis (Marsili et al., 2008; Jiao et al., 2011), S. loihica (Newton et al., 2009), S. baltica (von Canstein et al., 2007), S. frigidimarina (von Canstein et al., 2007) and S. decoloratioans (Li et al., 2010)) can biosynthesize the mediators required for MET for aerobic as well as anaerobic conditions. However, the ability to synthesize suitable amounts of these electron shuttles (especially for anaerobic conditions, where energy for biosynthesis is limited) is not univocal for all Shewanella species (e.g. [54]).
- Sad bacteria: http://www.clipartof.com/gallery/clipart/germ.html