we have a double-chambered MFC that produced an OCV that reached 220 mV in 1 h, and was getting higher. after 24 hours the OCV dropped down, and I don't know why.
I want to measure the generated current first to plot the I-V curve, then the power density curve.
I'm using a digital Multimeter for recording Voltage across either fixed or varied resistors.
Dear Nada A. Z. Okily,
Microbial fuel cells (MFCs) are bio electro chemical devices able to convert chemical energy into electricity. The effect of the external resistance on the performance of a MFC. Firstly, the state of the art of this topic has been comprehensively revised, and the effect of external resistance on cell voltage, anode potential, current and power generated, microbial diversity, structure and morphology of the biofilm, microbial metabolism and organic matter removal, coulombic efficiency, and time of stability is reported. Also, different methods to the control of external resistance as a function of internal resistance changing are explained. After that, the effect of changes in the external resistance on power generated and COD removal in a microscale MFC, used to treat wastewater, was studied. The obtained results indicated that when external resistance was increased, the power decreased. However, hysteresis was observed due to change in microbial diversity in the anode. During the first phase of increment of external resistance, the maximum power exerted, 1.69 × 10−3 mW, was obtained with a 2,700 Ω load. However, when decreasing the external resistance, the maximum power, 1.27 × 10−3 mW, was obtained with a 2,200 Ω load. Regarding COD removal, the effluent COD decreased when external resistance was increased, that is, the wastewater treatment was enhanced when external resistance was higher.
Here is link for reference.
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How does internal resistance influence the microbial fuel cell (MFC ...
Thanks, hope you will satisfy with answer, if have any question more kindly tell me.
Thanks
Dear Nedan,
Voltage reduction during the OCV evolution is due to the fact that the substrate is depleting. The substrate, such as organic compounds, has been utilized by the microbes to generate electricity in MFCs. Hence, if you are using a bioelectrochemical system in a batch mode, I strongly recommend you to perform feed (substrate) injection until two sequential equal peaks in voltage are obtained. Depending on the experiment, It is impossible to say the exact time for achieving two consecutive equal peaks in voltage (It may take several days to several months).
Variable external resistances are suggested to obtain polarization and power density curves.
For more information, I suggest the following article.
https://www.researchgate.net/publication/228100653_Single_chamber_microbial_fuel_cell_with_spiral_anode_for_dairy_wastewater_treatment
Best Regards,
Dear Nada,
The OCV represents the difference between the equilibrium potentials of both electrodes and (by definition) does not depend on any resistance. Make sure that you use a high internal resistance multimeter.
You may also use reference electrodes in both half cells and measure the electrode potential against those in the respective chamber. This will tell you whether the OCV is consistent:
OCV = (Ecathode - Eref, c) - (Eanode- Eref, a)
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