Electricity Generation from Mediator-Less MFC with Consortia of Carbon-Zinc Electrodes and CNT Doped PEM

Author Name: Anurag Vijay, *Tanu Kinra, Prof. Y. K. Vijay, Sarika Gupta
Author Email: tanuk.shona@gmail.com

Abstract

Microbial fuel cell is an applied aspect of microbes, i.e., using bacteria to generate electricity. It uses carbon source like sugars or any other organic waste. Bacteria like E. coli, Pseudomonas methanica, Pseudomonas fluorescence, Pseudomonas putida, Proteus vulgaris, Bacillus subtilis and many more that lives at anode are able to consume sugars under anaerobic conditions. They then release protons while depositing electrons externally on anode. Electrons and protons combine with an oxidant at cathode. In this process electricity is generated with carbon dioxide and other useful by products. Apparatus containing two electrodes viz. Carbon and Zinc electrodes, carbon nanotube doped proton exchange membrane and multi-meter for visualization of results by using E. coli culture was used. Microbial fuel cell was allowed to stand for three days, with the increase in incubation period the output voltage increases from nil to 1.23V. And on successive incubation the decline in the output was detected. Utmost voltage output recovered was 1.23V whereas the current being 8.04-8.08mA on the third day of incubation. With the increase in incubation it can be interpreted as some of the factor becoming limiting for further increment in the voltage was hindered. Recent research is based upon the increasing efficacy of microbes to produce electricity with enhancing production at commercial scale. Since it is a rechargeable approach it can be recharged by changing its culture media. Since it does not have any moving mechanical part, it can be used in remote areas as power supplement with no noise pollution as such.

Introduction

Some of the reduced fermentation products or microbially reduced artificial mediators can abiotically react with electrodes to yield a small electrical current. This type of metabolism does not typically result in an efficient conversion of organic compounds to electricity because only some metabolic end products will react with electrodes, and the microorganisms only incompletely oxidize their organic fuels. A new form of microbial respiration has recently been discovered in which microorganisms conserve energy to support growth by oxidizing organic compounds to carbon dioxide with direct quantitative electron transfer to electrodes. These organisms, termed electricigens, offer the possibility of efficiently converting organic compounds into electricity in self-sustaining systems with long-term stability [1]. Haacke and Klein have shown that electrical currents in plants are essentially a manifestation of vital phenomena, and that differences in electric potential are connected both with respiration and carbon assimilation[2].
The idea of using microbial cells in an attempt to produce electricity was first conceived at the turn of the nineteenth century. M.C. Potter (1911) was the first to perform work on the subject in 1911 [8]. Potter managed to generate electricity from E. coli, but the work was not to receive any major coverage. In 1931, however, Barnet Cohen drew more attention to the area when he created a number of microbial half fuel cells that, when connected in series, were capable of producing over 35 volts, though only with a current of 2 milliamps.
Carbon nanotubes (CNTs) have recently emerged as the wonder materials of the new century and are being considered for a whole host of applications ranging from large scale structures in automobiles to nanometer scale electronics. This includes significant features of electrical transport, which impact interpretation of measurements and suitability in advanced electronics.
The aim of this review is to study for the generation of good amount of electricity by the use of complete anaerbobic chamber and CNT-doped polycarbonate proton exchange membrane as this would allow more efficient electron transfer and better current yield.

Conclusion

Microbial fuel is different from that of better known conventional cells as conventional cells requires expensive catalyst to promote oxidation of electron donors. They also cannot be operated at room temperatures and are highly explosive and toxic. Also they have a complex and regulated distribution system whereas microbial fuel cells uses naturally occurring microbes to catalyze the oxidation of fuel, also can be operated at room temperature. As microbial fuel cells uses environment friendly microorganisms and there is no use of any toxic product and also no complex and regulated system exist, so microbial fuel cells are attractive power source in remote areas and besides only providing electricity also provides with other by-products like manure, biogas, etc. Also, there is no sound generation so no sound pollution as such. With Carbon Nanotubes an MFC works with better and much more efficiency with the same substrate and same micro-organism. So, with more development in the same, one can see the bright future especially with all villages getting lighted and kids studying under lamps.

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