| Title | ELECTRON TRANSFER FROM A SOLID-STATE ELECTRODE ASSISTED BY METHYL VIOLOGEN SUSTAINS EFFICIENT MICROBIAL REDUCTIV DECHLORINATION OF TCE |
| Abstract | The ability to transfer electrons, via an extracellular path, to solid surfaces is typically exploited by microorganisms which use insoluble electron acceptors, such as iron or manganese-oxides or inert electrodes in microbial fuel cells. The reverse process, i.e., the use of solid surfaces or electrodes as electron donors in microbial respirations, although largely unexplored, could potentially have important environmental applications, particularly for the removal of oxidized pollutants from contaminated groundwater or waste streams. Here we show, for the first time, that an electrochemical cell with a solid-state electrode polarized at -500 mV (vs standard hydrogen electrode), in combination with a low-potential redox mediator (methyl viologen), can efficiently transfer electrochemical reducing equivalents to microorganisms which respire using chlorinated solvents. By this approach, the reductive transformation of trichloroethene, a toxic yet common groundwater contaminant, to harmless end-products such as ethene and ethane could be performed. Furthermore, using a methyl-viologen-modified electrode we could even demonstrate that dechlorinating bacteria were able to accept reducing equivalents directly from the modified electrode surface. The innovative concept, based on the stimulation of dechlorination reactions through the use of solid state electrodes (we propose for this process the acronym BEARD: Bio-Electrochemically Assisted Reductive Dechlorination), holds promise for in situ bioremediation of chlorinated-solvent-contaminated groundwater, and has several potential advantages over traditional approaches based on the subsurface injection of organic compounds. The results of this study raise the possibility that immobilization of selected redox mediators may be a general strategy for stimulating and controlling a range of microbial reactions using insoluble electrodes as electron donors. |
| Source | Environmental science & technology 41 (7), pp. 2554–2559 |
| Journal | Environmental science & technology |
| Editor | American Chemical Society,, Easton, Pa., Stati Uniti d'America |
| Year | 2007 |
| Type | Articolo in rivista |
| DOI | 10.1021/es0624321 |
| Authors | AULENTA F. (1); CATERVI A. (1); MAJONE M. (1); PANERO S. (1); REALE P. (1); ROSSETTI S. (2) |
| Text | 42143 2007 10.1021/es0624321 ISI Web of Science WOS 000245258900079 ELECTRON TRANSFER FROM A SOLID STATE ELECTRODE ASSISTED BY METHYL VIOLOGEN SUSTAINS EFFICIENT MICROBIAL REDUCTIV DECHLORINATION OF TCE AULENTA F. 1 ; CATERVI A. 1 ; MAJONE M. 1 ; PANERO S. 1 ; REALE P. 1 ; ROSSETTI S. 2 1 Department of Chemistry Stanislao Cannizzaro , University of Rome La Sapienza , Piazzale Aldo Moro 5, 00185, Rome, Italy, 2 Water Research Institute, National Research Council IRSA CNR , Via Reno 1, 00198, Rome, Italy The ability to transfer electrons, via an extracellular path, to solid surfaces is typically exploited by microorganisms which use insoluble electron acceptors, such as iron or manganese oxides or inert electrodes in microbial fuel cells. The reverse process, i.e., the use of solid surfaces or electrodes as electron donors in microbial respirations, although largely unexplored, could potentially have important environmental applications, particularly for the removal of oxidized pollutants from contaminated groundwater or waste streams. Here we show, for the first time, that an electrochemical cell with a solid state electrode polarized at 500 mV vs standard hydrogen electrode , in combination with a low potential redox mediator methyl viologen , can efficiently transfer electrochemical reducing equivalents to microorganisms which respire using chlorinated solvents. By this approach, the reductive transformation of trichloroethene, a toxic yet common groundwater contaminant, to harmless end products such as ethene and ethane could be performed. Furthermore, using a methyl viologen modified electrode we could even demonstrate that dechlorinating bacteria were able to accept reducing equivalents directly from the modified electrode surface. The innovative concept, based on the stimulation of dechlorination reactions through the use of solid state electrodes we propose for this process the acronym BEARD Bio Electrochemically Assisted Reductive Dechlorination , holds promise for in situ bioremediation of chlorinated solvent contaminated groundwater, and has several potential advantages over traditional approaches based on the subsurface injection of organic compounds. The results of this study raise the possibility that immobilization of selected redox mediators may be a general strategy for stimulating and controlling a range of microbial reactions using insoluble electrodes as electron donors. 41 Electron Transfer from a Solid State Electrode Assisted by Methyl Viologen Sustains Efficient Microbial Reductive Dechlorination of TCE EST2007.pdf Articolo in rivista American Chemical Society, 0013 936X Environmental science technology Environmental science technology Environ. sci. technol. Environmental science technology. ES T Environmental science and technology simona.rossetti ROSSETTI SIMONA TA.P07.014.005 Risanamento di acque di falda |
