User:Anand Gupta/Notebook/Microbial Fuel Cell/2009/04/30

Microbial Fuel Cell

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Prototype 1: MFC from PEMFC Currently available Proton Exchange Membrane-based hydrogen fuel cells(PEMFCs) have a large number of similarities to two-chamber MFC designs proposed for this project. In developing an efficient and cost-effective MFC, we piloted the use of such a conventional fuel cell's components and design, slightly altered, in the hopes that it could not only confirm the correct function of our microbe setup culture (viability and metabolic yield), but also potentially allow us to exploit its design optimizations. In essence, the PEMFC used in this prototype consists of Pt-based Anode and Cathode, separated by a hydrated Nafion proton-exchange membrane. In hydrogen operation, H2(g) is fed into the Anode chamber, and O2(g)[possibly from air] is fed into the cathode. In this prototype, the PEMFC[modified], is supplied bacteria in liquid medium at the anode instead of H2. This bacteria performs the metabolic reactions that produce electrons and protons through the oxidation of glucose and use of an electron transport chain (see proposal). Electrons are transferred to the unreactive Pt-anode, whereas H+ is allowed to move through the PEM to the cathode where Pt catalyzes the reduction of O2 to H2O. Preflight Checklist Protocol 3 Materials 10ml E Coli k-12 in LB Broth Prepped through Protocol 2--Overnight Culture 20ml Syringe 1/8" diameter surgical tubing Alcohol/Chlorox [disinfectant] Proton Exchange Membrane Hydrogen Fuel Cell dH20 Fuel Cell Preparation 1) Load dH2O into syringe, eliminating air bubbles 2) Attach tubing to all input and output ports. Leave cathode ports open or attached to O2 supply 3) Attach syringe to anode input port 4) Gently pump ~5ml dH2O through anode input port, allowing FC to hydrate and water to exit through chamber output for anode. 5) Plug Anode output port. PEMFC is now clean and ready for use. Fuel Cell Operation 1) Load syringe with bacteria in medium, eliminating ALL air bubbles. Note that air bubbles severely compromise bacterial metabolic processes in the MFC 2) Unplug Anode output port. 3) Gently pump 1-2ml of bacteria and medium through anode input port, filling anode chamber and water to exit through output for anode. 4) Plug anode output and record voltage across electrodes. Voltage may take time to reach maximum. 5) From time to time, unplug anode output and pump additional bacteria + medium into anode input, collecting medium leaking from anode output.