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High rate membrane-less microbial electrolysis cell for continuous hydrogen production. Int J Hydrogen Energ

Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, QC H2P 2R2, Canada
International Journal of Hydrogen Energy (Impact Factor: 2.93). 01/2009; 34(2):672-677. DOI: 10.1016/j.ijhydene.2008.11.003

ABSTRACT This study demonstrates hydrogen production in a membrane-less continuous flow microbial electrolysis cell (MEC) with a gas-phase cathode. The MEC used a carbon felt anode and a gas diffusion cathode with a Pt loading of 0.5 mg cm−2. No proton exchange membrane (PEM) was used in the setup. Instead, the electrodes were separated by a J-cloth. The absence of a PEM as well as a short distance maintained between the electrodes (0.3 mm) resulted in a low internal resistance of 19 Ω. Due to an improved design, the volumetric hydrogen production rate reached 6.3 LSTP d−1. In spite of the PEM absence, methane concentration in the gas collection chamber was below 2.1% and the presence of hydrogen in the anodic chamber was never observed.

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    • "The electrons flow to the cathode through an external wire and combine with protons to form H 2 . The additional energy needed is supplied by an external power supply (Tartakovsky et al. 2009). Although the performance of MECs has improved significantly in recent years, their tests have been limited to the laboratory. "
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    ABSTRACT: The use of commercial electrodes as cathodes in a single-chamber microbial electrolysis cell has been investigated. The cell was operated in sequencing batch mode and the performance of the electrodes was compared with carbon cloth containing 0.5 mg Pt cm(-2). Overall H2 recovery [Formula: see text] was 66.7 ± 1.4, 58.7 ± 1.1 and 55.5 ± 1.5 % for Pt/CC, Ni and Ti mesh electrodes, respectively. Columbic efficiencies of the three cathodes were in the same range (74.8 ± 1.5, 77.6 ± 1.7 and 75.7 ± 1.2 % for Pt/CC, Ni and Ti mesh electrodes, respectively). A similar performance for the three cathodes under near-neutral pH and ambient temperature was obtained. The commercial electrodes are much cheaper than carbon cloth containing Pt. Low cost and good performance of these electrodes suggest they are suitable cathode materials for large scale application.
    Biotechnology Letters 06/2014; 36(10). DOI:10.1007/s10529-014-1565-7 · 1.74 Impact Factor
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    • "Oxygen is considered to be the most useful electron acceptor for practical applications of MFCs due to its abundance and high redox potential (Freguia et al. 2008). Two-chamber MFCs contain a membrane which result in pH gradients that can affect performance, and the catholyte needs to be aerated, which requires a high energy input (Clauwaert and Verstraete 2009; Tartakovsky et al. 2009). The use of single chamber, air-cathode designs avoids the need for a membrane or catholyte aeration, and avoids development of large pH changes. "
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    ABSTRACT: A large percentage of organic fuel consumed in a microbial fuel cell (MFC) is lost as a result of oxygen transfer through the cathode. In order to understand how this oxygen transfer affects the microbial community structure, reactors were operated in duplicate using three configurations: closed circuit (CC; with current generation), open circuit (OC; no current generation), and sealed off cathodes (SO; no current, with a solid plate placed across the cathode). Most (98 %) of the chemical oxygen demand (COD) was removed during power production in the CC reactor (maximum of 640 ± 10 mW/m(2)), with a low percent of substrate converted to current (coulombic efficiency of 26.5 ± 2.1 %). Sealing the cathode reduced COD removal to 7 %, but with an open cathode, there was nearly as much COD removal by the OC reactor (94.5 %) as the CC reactor. Oxygen transfer into the reactor substantially affected the composition of the microbial communities. Based on analysis of the biofilms using 16S rRNA gene pyrosequencing, microbes most similar to Geobacter were predominant on the anodes in the CC MFC (72 % of sequences), but the most abundant bacteria were Azoarcus (42 to 47 %) in the OC reactor, and Dechloromonas (17 %) in the SO reactor. Hydrogenotrophic methanogens were most predominant, with sequences most similar to Methanobacterium in the CC and SO reactor, and Methanocorpusculum in the OC reactors. These results show that oxygen leakage through the cathode substantially alters the bacterial anode communities, and that hydrogenotrophic methanogens predominate despite high concentrations of acetate. The predominant methanogens in the CC reactor most closely resembled those in the SO reactor, demonstrating that oxygen leakage alters methanogenic as well as general bacterial communities.
    Applied Microbiology and Biotechnology 06/2013; 97(22). DOI:10.1007/s00253-013-5025-4 · 3.81 Impact Factor
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    • "Applying additional voltage to the in situ potential generated by the bacterial cell, allows bioenergy generation like hydrogen and methane or various products like hydrogen peroxide at cathode (Liu et al. 2005b; Venkata Mohan and Lenin Babu 2011). Previously, this bioelectrolytic process has been referred to as a biocatalyzed electrolysis cell (BEC) or a bioelectrochemically assisted microbial reactor (BEAMR) (Logan et al. 2005; Ditzig et al. 2007; Tartakovsky et al. 2009) and for the past few years it has been termed as electrohydrogenesis or microbial electrolysis. The performance of MEC has significantly improved within few years after its discovery (Liu et al. 2005b; Logan et al. 2005). "
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    ABSTRACT: The energy gain in microbes is driven by oxidizing an electron donor and reducing an electron acceptor. Variation in the electron acceptor conditions creates a feasibility to harness energy. In order to support the microbial respiration, electrons will transfer to the exocellular medium toward the available electron acceptor, especially in the absence of oxygen. The microbes can use a wide range of electron acceptors such as metals, nutrients, minerals, etc., including solid electrodes. When the microbes use the solid electrode as electron acceptors, the setup is called microbial fuel cell (MFC) and the electrons can be harvested and used for different applications.MFC can be defined as a microbially catalyzed electrochemical system which can facilitate the direct conversion of substrate to electricity through a cascade of redox reactions, especially in the absence of oxygen. Linking the microbial metabolism to anode and then transmitting the electrons to cathode generates a net electrical power from the degradation of available electron donor. This concept of MFC operation has expanded considerable interest in the recent research due to its application in the energy recovery from wastewater. Microbes in MFC can also use variety of organic or inorganic electron donors as well as acceptors to produce a surfeit of desirable biofuels or biochemicals which is termed as microbial electro- synthesis. Apart from the electrogensis, the applications of MFC are widespread in different fields including waste/wastewater remediation, toxic pollutants/xenobiot ics removal, recovery of commercially viable products, sequestration of CO2, harvesting the energy stored in marine sediments, desalination, etc. In this chapter, an attempt was made to bring out all the existing applications of MFC into one platform to make a comprehensive understanding on the inherent potential of microbial metabolism, when the designated electron acceptor is present.
    Biofuel Technologies: Recent Developments, Edited by VK Gupta, MG Tuohy, 01/2013: chapter Microbial Fuel Cells for Sustainable Bioenergy Generation: Principles and Perspective Applications (Chap 11): pages p335-368; Spinger-Verlag Berlin., ISBN: 978-3-642-34518-0
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