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Title: Ion Exchange Membrane Influence on Ohmic Resistance

item FORNERO, JEFFREY - Washington University
item ROSENBAUM, MIRIAM - Cornell University - New York
item Cotta, Michael
item ANGENENT, LARGUS - Cornell University - New York

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/12/2009
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Selection of the proper ion exchange membrane can have a significant influence on bioelectrochemical system (BES) power densities. Because ions move across the membrane to achieve electroneutrality, the ion transport resistance (ohmic loss) needs to be minimized to increase power densities. Ohmic losses are influenced by the: (1) ionic transport processes within the anolyte and catholyte (i.e., solution losses due to diffusion and electro-migration processes), and (2) ionic transport processes across the exchange membrane (i.e., membrane losses due to the specific material features of the membrane and characteristics of the electrolyte solutions). With stable anode conditions, we tested both a microbial fuel cell (MFC) with an anion exchange membrane (AEM) and a cation exchange membrane (CEM). Tests were conducted with a phosphate-buffered catholyte maintained at a constant pH. Anode conditions were maintained at steady state conditions with the continuous addition of a synthetic wastewater substrate based on sucrose. The MFC produced 65-108% more power with the AEMs in comparison to the CEMs under the same operating conditions. We believe that the increased power results from favorable ion gradients across the exchange membranes resulting in an internal resistance of 61.2 ohms and 93.6 ohms for the AEM and CEM, respectively. In a real-world situation, ion gradients between the anode and cathodes are dependent on the encountered wastewater solution (anolyte), selected catholyte, and the redox half reaction products for each cell. Based on this information, the engineer can decide between AEM and CEM to minimize the overall MFC resistance.