Sample records for air cathode microbial

  1. Progress of air-breathing cathode in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Zejie; Mahadevan, Gurumurthy Dummi; Wu, Yicheng; Zhao, Feng

    2017-07-01

    Microbial fuel cell (MFC) is an emerging technology to produce green energy and vanquish the effects of environmental contaminants. Cathodic reactions are vital for high electrical power density generated from MFCs. Recently tremendous attentions were paid towards developing high performance air-breathing cathodes. A typical air-breathing cathode comprises of electrode substrate, catalyst layer, and air-diffusion layer. Prior researches demonstrated that each component influenced the performance of air-breathing cathode MFCs. This review summarized the progress in development of the individual component and elaborated main factors to the performance of air-breathing cathode.

  2. Durability and regeneration of activated carbon air-cathodes in long-term operated microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Enren; Wang, Feng; Yu, Qingling; Scott, Keith; Wang, Xu; Diao, Guowang

    2017-08-01

    The performance of activated carbon catalyst in air-cathodes in microbial fuel cells was investigated over one year. A maximum power of 1722 mW m-2 was produced within the initial one-month microbial fuel cell operation. The air-cathodes produced a maximum power >1200 mW m-2 within six months, but gradually became a limiting factor for the power output in prolonged microbial fuel cell operation. The maximum power decreased by 55% when microbial fuel cells were operated over one year due to deterioration in activated carbon air-cathodes. While salt/biofilm removal from cathodes experiencing one-year operation increased a limiting performance enhancement in cathodes, a washing-drying-pressing procedure could restore the cathode performance to its original levels, although the performance restoration was temporary. Durable cathodes could be regenerated by re-pressing activated carbon catalyst, recovered from one year deteriorated air-cathodes, with new gas diffusion layer, resulting in ∼1800 mW m-2 of maximum power production. The present study indicated that activated carbon was an effective catalyst in microbial fuel cell cathodes, and could be recovered for reuse in long-term operated microbial fuel cells by simple methods.

  3. Inhibition of microbial growth on air cathodes of single chamber microbial fuel cells by incorporating enrofloxacin into the catalyst layer.

    PubMed

    Liu, Weifeng; Cheng, Shaoan; Sun, Dan; Huang, Haobin; Chen, Jie; Cen, Kefa

    2015-10-15

    The inevitable growth of aerobic bacteria on the surface of air cathodes is an important factor reducing the performance stability of air cathode single-chamber membrane-free microbial fuel cells (MFCs). Thus searching for effective methods to inhibit the cathodic microbial growth is critical for the practical application of MFCs. In this study, enrofloxacin (ENR), a broad spectrum fluoroquinolone antibiotic, was incorporated into the catalyst layer of activated carbon air cathodes (ACACs) to inhibit the cathodic microbial growth. The biomass content on ACACs was substantially reduced by 60.2% with ENR treatment after 91 days of MFCs operation. As a result of the inhibited microbial growth, the oxygen reduction catalytic performance of the ENR treated ACACs was much stable compared to the fast performance decline of the untreated control. Consequently, a quite stable electricity production was obtained for the MFCs with the ENR treated ACACs, in contrast with a 22.5% decrease in maximum power density of the MFCs with the untreated cathode. ENR treatment of ACACs showed minimal effects on the anode performance. These results indicate that incorporating antibiotics into ACACs should be a simple and effective strategy to inhibit the microbial growth and improve the long-term stability of the performance of air cathode and the electricity production of MFCs. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Pressurized air cathodes for enhanced stability and power generation by microbial fuel cells

    NASA Astrophysics Data System (ADS)

    He, Weihua; Yang, Wulin; Tian, Yushi; Zhu, Xiuping; Liu, Jia; Feng, Yujie; Logan, Bruce E.

    2016-11-01

    Large differences between the water and air pressure in microbial fuel cells (MFCs) can deform and damage cathodes. To avoid deformation, the cathode air pressure was controlled to balance pressure differences between the air and water. Raising the air pressures from 0 to 10 kPa at a set cathode potential of -0.3 V (versus Ag/AgCl) enhanced cathode performance by 17%, but pressures ≥25 kPa decreased current and resulted in air leakage into the solution. Matching the air pressure with the water pressure avoided cathode deformation and improved performance. The maximum power density increased by 15%, from 1070 ± 20 to 1230 ± 70 mW m-2, with balanced air and water pressures of 10-25 kPa. Oxygen partial pressures ≥12.5 kPa in the cathode compartment maintained the oxygen reduction rate to be within 92 ± 1% of that in ambient air. The use of pressurized air flow through the cathode compartments can enable closer spacing of the cathodes compared to passive gas transfer systems, which could make the reactor design more compact. The energy cost of pressurizing the cathodes was estimated to be smaller than the increase in power that resulted from the use of pressurized cathodes.

  5. Air-cathode microbial fuel cell array: a device for identifying and characterizing electrochemically active microbes.

    PubMed

    Hou, Huijie; Li, Lei; de Figueiredo, Paul; Han, Arum

    2011-01-15

    Microbial fuel cells (MFCs) have generated excitement in environmental and bioenergy communities due to their potential for coupling wastewater treatment with energy generation and powering diverse devices. The pursuit of strategies such as improving microbial cultivation practices and optimizing MFC devices has increased power generating capacities of MFCs. However, surprisingly few microbial species with electrochemical activity in MFCs have been identified because current devices do not support parallel analyses or high throughput screening. We have recently demonstrated the feasibility of using advanced microfabrication methods to fabricate an MFC microarray. Here, we extend these studies by demonstrating a microfabricated air-cathode MFC array system. The system contains 24 individual air-cathode MFCs integrated onto a single chip. The device enables the direct and parallel comparison of different microbes loaded onto the array. Environmental samples were used to validate the utility of the air-cathode MFC array system and two previously identified isolates, 7Ca (Shewanella sp.) and 3C (Arthrobacter sp.), were shown to display enhanced electrochemical activities of 2.69 mW/m(2) and 1.86 mW/m(2), respectively. Experiments using a large scale conventional air-cathode MFC validated these findings. The parallel air-cathode MFC array system demonstrated here is expected to promote and accelerate the discovery and characterization of electrochemically active microbes. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. Performance and microbial ecology of air-cathode microbial fuel cells with layered electrode assemblies.

    PubMed

    Butler, Caitlyn S; Nerenberg, Robert

    2010-05-01

    Microbial fuel cells (MFCs) can be built with layered electrode assemblies, where the anode, proton exchange membrane (PEM), and cathode are pressed into a single unit. We studied the performance and microbial community structure of MFCs with layered assemblies, addressing the effect of materials and oxygen crossover on the community structure. Four MFCs with layered assemblies were constructed using Nafion or Ultrex PEMs and a plain carbon cloth electrode or a cathode with an oxygen-resistant polytetrafluoroethylene diffusion layer. The MFC with Nafion PEM and cathode diffusion layer achieved the highest power density, 381 mW/m(2) (20 W/m(3)). The rates of oxygen diffusion from cathode to anode were three times higher in the MFCs with plain cathodes compared to those with diffusion-layer cathodes. Microsensor studies revealed little accumulation of oxygen within the anode cloth. However, the abundance of bacteria known to use oxygen as an electron acceptor, but not known to have exoelectrogenic activity, was greater in MFCs with plain cathodes. The MFCs with diffusion-layer cathodes had high abundance of exoelectrogenic bacteria within the genus Geobacter. This work suggests that cathode materials can significantly influence oxygen crossover and the relative abundance of exoelectrogenic bacteria on the anode, while PEM materials have little influence on anode community structure. Our results show that oxygen crossover can significantly decrease the performance of air-cathode MFCs with layered assemblies, and therefore limiting crossover may be of particular importance for these types of MFCs.

  7. A solvent-free microbial-activated air cathode battery paper platform made with pencil-traced graphite electrodes.

    PubMed

    Lee, Seung Ho; Ban, Ju Yeon; Oh, Chung-Hun; Park, Hun-Kuk; Choi, Samjin

    2016-06-23

    We present the fabrication of an ultra-low cost, disposable, solvent-free air cathode all-paper microbial fuel cell (MFC) that does not utilize any chemical treatments. The anode and cathode were fabricated by depositing graphite particles by drawing them on paper with a pencil (four strokes). Hydrophobic parchment paper was used as a proton exchange membrane (PEM) to allow only H(+) to pass. Air cathode MFC technology, where O2 was used as an electron acceptor, was implemented on the paper platform. The bioelectric current was generated by an electrochemical process involving the redox couple of microbial-activated extracellular electron transferred electrons, PEM-passed H(+), and O2 in the cathode. A fully micro-integrated pencil-traced MFC showed a fast start-time, producing current within 10 s after injection of bacterial cells. A single miniaturized all-paper air cathode MFC generated a maximum potential of 300 mV and a maximum current of 11 μA during 100 min after a single injection of Shewanella oneidensis. The micro-fabricated solvent-free air cathode all-paper MFC generated a power of 2,270 nW (5.68 mW/m(2)). The proposed solvent-free air cathode paper-based MFC device could be used for environmentally-friendly energy storage as well as in single-use medical power supplies that use organic matter.

  8. A solvent-free microbial-activated air cathode battery paper platform made with pencil-traced graphite electrodes

    PubMed Central

    Lee, Seung Ho; Ban, Ju Yeon; Oh, Chung-Hun; Park, Hun-Kuk; Choi, Samjin

    2016-01-01

    We present the fabrication of an ultra-low cost, disposable, solvent-free air cathode all-paper microbial fuel cell (MFC) that does not utilize any chemical treatments. The anode and cathode were fabricated by depositing graphite particles by drawing them on paper with a pencil (four strokes). Hydrophobic parchment paper was used as a proton exchange membrane (PEM) to allow only H+ to pass. Air cathode MFC technology, where O2 was used as an electron acceptor, was implemented on the paper platform. The bioelectric current was generated by an electrochemical process involving the redox couple of microbial-activated extracellular electron transferred electrons, PEM-passed H+, and O2 in the cathode. A fully micro-integrated pencil-traced MFC showed a fast start-time, producing current within 10 s after injection of bacterial cells. A single miniaturized all-paper air cathode MFC generated a maximum potential of 300 mV and a maximum current of 11 μA during 100 min after a single injection of Shewanella oneidensis. The micro-fabricated solvent-free air cathode all-paper MFC generated a power of 2,270 nW (5.68 mW/m2). The proposed solvent-free air cathode paper-based MFC device could be used for environmentally-friendly energy storage as well as in single-use medical power supplies that use organic matter. PMID:27333815

  9. A solvent-free microbial-activated air cathode battery paper platform made with pencil-traced graphite electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Seung Ho; Ban, Ju Yeon; Oh, Chung-Hun; Park, Hun-Kuk; Choi, Samjin

    2016-06-01

    We present the fabrication of an ultra-low cost, disposable, solvent-free air cathode all-paper microbial fuel cell (MFC) that does not utilize any chemical treatments. The anode and cathode were fabricated by depositing graphite particles by drawing them on paper with a pencil (four strokes). Hydrophobic parchment paper was used as a proton exchange membrane (PEM) to allow only H+ to pass. Air cathode MFC technology, where O2 was used as an electron acceptor, was implemented on the paper platform. The bioelectric current was generated by an electrochemical process involving the redox couple of microbial-activated extracellular electron transferred electrons, PEM-passed H+, and O2 in the cathode. A fully micro-integrated pencil-traced MFC showed a fast start-time, producing current within 10 s after injection of bacterial cells. A single miniaturized all-paper air cathode MFC generated a maximum potential of 300 mV and a maximum current of 11 μA during 100 min after a single injection of Shewanella oneidensis. The micro-fabricated solvent-free air cathode all-paper MFC generated a power of 2,270 nW (5.68 mW/m2). The proposed solvent-free air cathode paper-based MFC device could be used for environmentally-friendly energy storage as well as in single-use medical power supplies that use organic matter.

  10. Multi-variable mathematical models for the air-cathode microbial fuel cell system

    DOE PAGES

    Ou, Shiqi; Kashima, Hiroyuki; Aaron, Douglas S.; ...

    2016-03-10

    This research adopted the version control system into the model construction for the single chamber air-cathode microbial fuel cell (MFC) system, to understand the interrelation of biological, chemical, and electrochemical reactions. The anodic steady state model was used to consider the chemical species diffusion and electric migration influence to the MFC performance. In the cathodic steady state model, the mass transport and reactions in a multi-layer, abiotic cathode and multi-bacteria cathode biofilm were simulated. Transport of hydroxide was assumed for cathodic pH change. This assumption is an alternative to the typical notion of proton consumption during oxygen reduction to explainmore » elevated cathode pH. The cathodic steady state model provided the power density and polarization curve performance results that can be compared to an experimental MFC system. Another aspect we considered was the relative contributions of platinum catalyst and microbes on the cathode to the oxygen reduction reaction (ORR). We found simulation results showed that the biocatalyst in a cathode that includes a Pt/C catalyst likely plays a minor role in ORR, contributing up to 8% of the total power calculated by the models.« less

  11. Multi-variable mathematical models for the air-cathode microbial fuel cell system

    NASA Astrophysics Data System (ADS)

    Ou, Shiqi; Kashima, Hiroyuki; Aaron, Douglas S.; Regan, John M.; Mench, Matthew M.

    2016-05-01

    This research adopted the version control system into the model construction for the single chamber air-cathode microbial fuel cell (MFC) system, to understand the interrelation of biological, chemical, and electrochemical reactions. The anodic steady state model was used to consider the chemical species diffusion and electric migration influence to the MFC performance. In the cathodic steady state model, the mass transport and reactions in a multi-layer, abiotic cathode and multi-bacteria cathode biofilm were simulated. Transport of hydroxide was assumed for cathodic pH change. This assumption is an alternative to the typical notion of proton consumption during oxygen reduction to explain elevated cathode pH. The cathodic steady state model provided the power density and polarization curve performance results that can be compared to an experimental MFC system. Another aspect considered was the relative contributions of platinum catalyst and microbes on the cathode to the oxygen reduction reaction (ORR). Simulation results showed that the biocatalyst in a cathode that includes a Pt/C catalyst likely plays a minor role in ORR, contributing up to 8% of the total power calculated by the models.

  12. External CO2 and water supplies for enhancing electrical power generation of air-cathode microbial fuel cells.

    PubMed

    Ishizaki, So; Fujiki, Itto; Sano, Daisuke; Okabe, Satoshi

    2014-10-07

    Alkalization on the cathode electrode limits the electrical power generation of air-cathode microbial fuel cells (MFCs), and thus external proton supply to the cathode electrode is essential to enhance the electrical power generation. In this study, the effects of external CO2 and water supplies to the cathode electrode on the electrical power generation were investigated, and then the relative contributions of CO2 and water supplies to the total proton consumption were experimentally evaluated. The CO2 supply decreased the cathode pH and consequently increased the power generation. Carbonate dissolution was the main proton source under ambient air conditions, which provides about 67% of total protons consumed for the cathode reaction. It is also critical to adequately control the water content on the cathode electrode of air-cathode MFCs because the carbonate dissolution was highly dependent on water content. On the basis of these experimental results, the power density was increased by 400% (143.0 ± 3.5 mW/m(2) to 575.0 ± 36.0 mW/m(2)) by supplying a humid gas containing 50% CO2 to the cathode chamber. This study demonstrates that the simultaneous CO2 and water supplies to the cathode electrode were effective to increase the electrical power generation of air-cathode MFCs for the first time.

  13. Separator electrode assembly (SEA) with 3-dimensional bioanode and removable air-cathode boosts microbial fuel cell performance

    NASA Astrophysics Data System (ADS)

    Oliot, M.; Etcheverry, L.; Mosdale, A.; Basseguy, R.; Délia, M.-L.; Bergel, A.

    2017-07-01

    Separator electrode assemblies (SEAs) were designed by associating a microbial anode with an air-cathode on each side of three different kinds of separator: plastic grid, J-cloth and baking paper. The SEA was designed to allow the air-cathode be removed and replaced without disturbing the bioanode. Power densities up to 6.4 W m-2 were produced by the Grid-SEAs (on average 5.9 ± 0.5 W m-2) while JCloth-SEAs and Paper-SEAs produced 4.8 ± 0.3 and 1.8 ± 0.1 W m-2, respectively. Power densities decreased with time mainly because of fast deterioration of the cathode kinetics. They always increased again when the air-cathodes were replaced by new ones; the Grid-SEAs were thus boosted above 4 W m-2 after 7 weeks of operation. The theoretical analysis of SEA functioning suggested that the high performance of the Grid-SEAs was due to the combination of several virtuous phenomena: the efficient pH balance thanks to free diffusion through the large-mesh grid, the likely mitigation of oxygen crossover thanks to the 3-dimensional structure of the bioanode and the possibility of overcoming cathode fouling by replacing it during MFC operation. Finally, the microbial community of all bioanodes showed stringent selection of Proteiniphilum acetatigenes in proportion with the performance.

  14. A Single-Chamber Microbial Fuel Cell without an Air Cathode

    PubMed Central

    Nimje, Vanita Roshan; Chen, Chien-Cheng; Chen, Hau-Ren; Chen, Chien-Yen; Tseng, Min-Jen; Cheng, Kai-Chien; Shih, Ruey-Chyuan; Chang, Young-Fo

    2012-01-01

    Microbial fuel cells (MFCs) represent a novel technology for wastewater treatment with electricity production. Electricity generation with simultaneous nitrate reduction in a single-chamber MFC without air cathode was studied, using glucose (1 mM) as the carbon source and nitrate (1 mM) as the final electron acceptor employed by Bacillus subtilis under anaerobic conditions. Increasing current as a function of decreased nitrate concentration and an increase in biomass were observed with a maximum current of 0.4 mA obtained at an external resistance (Rext) of 1 KΩ without a platinum catalyst of air cathode. A decreased current with complete nitrate reduction, with further recovery of the current immediately after nitrate addition, indicated the dependence of B. subtilis on nitrate as an electron acceptor to efficiently produce electricity. A power density of 0.0019 mW/cm2 was achieved at an Rext of 220 Ω. Cyclic voltammograms (CV) showed direct electron transfer with the involvement of mediators in the MFC. The low coulombic efficiency (CE) of 11% was mainly attributed to glucose fermentation. These results demonstrated that electricity generation is possible from wastewater containing nitrate, and this represents an alternative technology for the cost-effective and environmentally benign treatment of wastewater. PMID:22489190

  15. Performance and microbial diversity of microbial fuel cells coupled with different cathode types during simultaneous azo dye decolorization and electricity generation.

    PubMed

    Hou, Bin; Hu, Yongyou; Sun, Jian

    2012-05-01

    To study the effect of cathode type on performance and microbial diversity of the MFC, aerobic biocathode and air-cathode were incorporated into microbial fuel cells (MFCs) which were explored for simultaneous azo dye decolorization and electricity generation. The electrochemical impedance spectroscopy (EIS) results demonstrated that the catalytic activity of the microorganisms on the biocathode surface was comparable with that of the platinum coated on the air-cathode. The power density achieved by using biocathode was lower than air-cathode, but the biocathode could greatly improve the Congo red decolorization rate. By using the biocathode, 96.4% decolorization of Congo red was obtained within 29 h, whereas, about 107 h was required to achieve the same decolorization efficiency with the air-cathode. 16S rRNA sequencing analysis demonstrated a phylogenetic diversity in the communities of the anode biofilm and showed clear differences between the anode-attached populations in the MFCs with a different cathode type. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Electrode Modification and Optimization in Air-Cathode Single-Chamber Microbial Fuel Cells.

    PubMed

    Wang, Yanhua; Wu, Jiayan; Yang, Shengke; Li, Huihui; Li, Xiaoping

    2018-06-27

    Due to the known problems of microbial fuel cells (MFCs), such as low electricity generation performance and high cost of operation, we modified the electrode with graphene and polyaniline (PANI) is a single-chamber air-cathode MFC and then evaluated the effects of electrode modification on MFC electricity generation performance. Carbon cloth electrodes (unmodified, CC; graphene-modified, G/CC; and polyaniline-graphene-modified, PANI-G/CC) were prepared using the impregnation method. Sulfonated cobalt phthalocyanine (CoPcS) was then introduced as a cathode catalyst. The Co-PANI-G/CC cathode showed higher catalytic activity toward oxygen reduction compared with other electrodes. The maximum power density of the MFC with Co-PANI-G/CC cathode was 32.2 mW/m², which was 1.8 and 6.1 times higher than the value obtained with Co-G/CC and Co/CC cathodes, respectively. This indicates a significant improvement in the electricity generation of single-chamber MFCs and provides a simple, effective cathode modification method. Furthermore, we constructed single-chamber MFCs using the modified anode and cathode and analyzed electricity generation and oxytetracycline (OTC) degradation with different concentrations of OTC as the fuel. With increasing added OTC concentration, the MFC performance in both electricity generation and OTC degradation gradually decreased. However, when less than 50 mg/L OTC was added, the 5-day degradation rate of OTC reached more than 90%. It is thus feasible to process OTC-containing wastewater and produce electricity using single-chamber MFCs, which provides a new concept for wastewater treatment.

  17. Effects of hydraulic pressure on the performance of single chamber air-cathode microbial fuel cells.

    PubMed

    Cheng, Shaoan; Liu, Weifeng; Guo, Jian; Sun, Dan; Pan, Bin; Ye, Yaoli; Ding, Weijun; Huang, Haobin; Li, Fujian

    2014-06-15

    Scaling up of microbial fuel cells (MFCs) without losing power density requires a thorough understanding of the effect of hydraulic pressure on MFC performance. In this work, the performance of an activated carbon air-cathode MFC was evaluated under different hydraulic pressures. The MFC under 100 mmH2O hydraulic pressure produced a maximum power density of 1260 ± 24 mW m(-2), while the power density decreased by 24.4% and 44.7% as the hydraulic pressure increased to 500 mmH2O and 2000 mmH2O, respectively. Notably, the performance of both the anode and the cathode had decreased under high hydraulic pressures. Electrochemical impedance spectroscopy tests of the cathode indicated that both charge transfer resistance and diffusion transfer resistance increased with the increase in hydraulic pressure. Denaturing gradient gel electrophoresis of PCR-amplified partial 16S rRNA genes demonstrated that the similarity among anodic biofilm communities under different hydraulic pressures was ≥ 90%, and the communities of all MFCs were dominated by Geobacter sp. These results suggested that the reduction in power output of the single chamber air-cathode MFC under high hydraulic pressures can be attributed to water flooding of the cathode and suppression the metabolism of anodic exoelectrogenic bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Continuous treatment of high strength wastewaters using air-cathode microbial fuel cells.

    PubMed

    Kim, Kyoung-Yeol; Yang, Wulin; Evans, Patrick J; Logan, Bruce E

    2016-12-01

    Treatment of low strength wastewaters using microbial fuel cells (MFCs) has been effective at hydraulic retention times (HRTs) similar to aerobic processes, but treatment of high strength wastewaters can require longer HRTs. The use of two air-cathode MFCs hydraulically connected in series was examined to continuously treat high strength swine wastewater (7-8g/L of chemical oxygen demand) at an HRT of 16.7h. The maximum power density of 750±70mW/m 2 was produced after 12daysof operation. However, power decreased by 85% after 185d of operation due to serious cathode fouling. COD removal was improved by using a lower external resistance, and COD removal rates were substantially higher than those previously reported for a low strength wastewater. However, removal rates were inconsistent with first order kinetics as the calculated rate constant was an order of magnitude lower than rate constant for the low strength wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Graphite fiber brush anodes for increased power production in air-cathode microbial fuel cells.

    PubMed

    Logan, Bruce; Cheng, Shaoan; Watson, Valerie; Estadt, Garett

    2007-05-01

    To efficiently generate electricity using bacteria in microbial fuel cells (MFCs), highly conductive noncorrosive materials are needed that have a high specific surface area (surface area per volume) and an open structure to avoid biofouling. Graphite brush anodes, consisting of graphite fibers wound around a conductive, but noncorrosive metal core, were examined for power production in cube (C-MFC) and bottle (B-MFC) air-cathode MFCs. Power production in C-MFCs containing brush electrodes at 9600 m2/m3 reactor volume reached a maximum power density of 2400 mW/m2 (normalized to the cathode projected surface area), or 73 W/m3 based on liquid volume, with a maximum Coulombic efficiency (CE) of 60%. This power density, normalized by cathode projected area, is the highest value yet achieved by an air-cathode system. The increased power resulted from a reduction in internal resistance from 31 to 8 Q. Brush electrodes (4200 m2/m3) were also tested in B-MFCs, consisting of a laboratory media bottle modified to have a single side arm with a cathode clamped to its end. B-MFCs inoculated with wastewater produced up to 1430 mW/m2 (2.3 W/m3, CE = 23%) with brush electrodes, versus 600 mW/m2 with a plain carbon paper electrode. These findings show that brush anodes that have high surface areas and a porous structure can produce high power densities, and therefore have qualities that make them ideal for scaling up MFC systems.

  20. Performance of air-cathode stacked microbial fuel cells systems for wastewater treatment and electricity production.

    PubMed

    Estrada-Arriaga, Edson Baltazar; Guillen-Alonso, Yvonne; Morales-Morales, Cornelio; García-Sánchez, Liliana; Bahena-Bahena, Erick Obed; Guadarrama-Pérez, Oscar; Loyola-Morales, Félix

    2017-07-01

    Two different air-cathode stacked microbial fuel cell (MFC) configurations were evaluated under continuous flow during the treatment of municipal wastewater and electricity production at a hydraulic retention time (HRT) of 3, 1, and 0.5 d. Stacked MFC 1 was formed by 20 individual air-cathode MFC units. The second stacked MFC (stacked MFC 2) consisted of 40 air-cathode MFC units placed in a shared reactor. The maximum voltages produced at closed circuit (1,000 Ω) were 170 mV for stacked MFC 1 and 94 mV for stacked MFC 2. Different power densities in each MFC unit were obtained due to a potential drop phenomenon and to a change in chemical oxygen demand (COD) concentrations inside reactors. The maximum power densities from individual MFC units were up to 1,107 mW/m 2 for stacked MFC 1 and up to 472 mW/m 2 for stacked MFC 2. The maximum power densities in stacked MFC 1 and MFC 2 connected in series were 79 mW/m 2 and 4 mW/m 2 , respectively. Electricity generation and COD removal efficiencies were reduced when the HRT was decreased. High removal efficiencies of 84% of COD, 47% of total nitrogen, and 30% of total phosphorus were obtained during municipal wastewater treatment.

  1. Effects of proton exchange membrane on the performance and microbial community composition of air-cathode microbial fuel cells.

    PubMed

    Lee, Yun-Yeong; Kim, Tae Gwan; Cho, Kyung-Suk

    2015-10-10

    This study investigated the effects of proton exchange membranes (PEMs) on performance and microbial community of air-cathode microbial fuel cells (MFCs). Air-cathode MFCs with reactor volume of 1L were constructed in duplicate with or without PEM (designated as ACM-MFC and AC-MFC, respectively) and fed with a mixture of glucose and acetate (1:1, w:w). The maximum power density and coulombic efficiency did not differ between MFCs in the absence or presence of a PEM. However, PEM use adversely affected maximum voltage production and the rate of organic compound removal (p<0.05). Quantitative droplet digital PCR indicated that AC-MFCs had a greater bacterial population than ACM-MFCs (p<0.05). Likewise, ribosomal tag pyrosequencing revealed that the diversity index of bacterial communities was greater for AC-MFCs (p<0.05). Network analysis revealed that the most abundant genus was Enterococcus, which comprised ≥62% of the community and was positively associated with PEM and negatively associated with the rate of chemical oxygen demand (COD) removal (Pearson correlation>0.9 and p<0.05). Geobacter, which is known as an exoelectrogen, was positively associated with maximum power density and negatively associated with PEM. Thus, these results suggest that the absence of PEM favored the growth of Geobacter, a key player for electricity generation in MFC systems. Taken together, these findings demonstrate that MFC systems without PEM are more efficient with respect to power production and COD removal as well as exoelectrogen growth. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Microbial stratification structure within cathodic biofilm of the microbial fuel cell using the freezing microtome method.

    PubMed

    Li, Xiao; Lu, Yaobin; Luo, Haiping; Liu, Guangli; Zhang, Renduo

    2017-10-01

    The aim of this study was to investigate the microbial stratification structure within cathodic biofilm of the microbial fuel cell (MFC) using the freezing microtome method. Experiments were conducted in a single-chamber air-cathode MFC with 0.8g/L maltodextrin as substrate for ∼30d operation. The maximum power density was 945±10mW/m 2 in the MFC. Maltodextrin resulted in the relative abundance of Candidatus Saccharibacteria of 37.0% in the anodic biofilm. Different bacterial communities were identified in different layers within the cathodic biofilm. The relative abundance of Enterococcus was 3.7%, 10.5%, and 1.6% in the top (100-150μm), middle (50-100μm), and bottom (0-50μm) layers, respectively. Higher bacterial viability was observed within the top and bottom layers of the cathodic biofilm. Understanding the stratification of bacterial community in cathodic biofilm should be important to control the cathodic biofilm in the MFC. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Microbial community structures differentiated in a single-chamber air-cathode microbial fuel cell fueled with rice straw hydrolysate.

    PubMed

    Wang, Zejie; Lee, Taekwon; Lim, Bongsu; Choi, Chansoo; Park, Joonhong

    2014-01-17

    The microbial fuel cell represents a novel technology to simultaneously generate electric power and treat wastewater. Both pure organic matter and real wastewater can be used as fuel to generate electric power and the substrate type can influence the microbial community structure. In the present study, rice straw, an important feedstock source in the world, was used as fuel after pretreatment with diluted acid method for a microbial fuel cell to obtain electric power. Moreover, the microbial community structures of anodic and cathodic biofilm and planktonic culturewere analyzed and compared to reveal the effect of niche on microbial community structure. The microbial fuel cell produced a maximum power density of 137.6 ± 15.5 mW/m2 at a COD concentration of 400 mg/L, which was further increased to 293.33 ± 7.89 mW/m2 through adjusting the electrolyte conductivity from 5.6 mS/cm to 17 mS/cm. Microbial community analysis showed reduction of the microbial diversities of the anodic biofilm and planktonic culture, whereas diversity of the cathodic biofilm was increased. Planktonic microbial communities were clustered closer to the anodic microbial communities compared to the cathodic biofilm. The differentiation in microbial community structure of the samples was caused by minor portion of the genus. The three samples shared the same predominant phylum of Proteobacteria. The abundance of exoelectrogenic genus was increased with Desulfobulbus as the shared most abundant genus; while the most abundant exoelectrogenic genus of Clostridium in the inoculum was reduced. Sulfate reducing bacteria accounted for large relative abundance in all the samples, whereas the relative abundance varied in different samples. The results demonstrated that rice straw hydrolysate can be used as fuel for microbial fuel cells; microbial community structure differentiated depending on niches after microbial fuel cell operation; exoelectrogens were enriched; sulfate from rice straw

  4. Microbial community structures differentiated in a single-chamber air-cathode microbial fuel cell fueled with rice straw hydrolysate

    PubMed Central

    2014-01-01

    Background The microbial fuel cell represents a novel technology to simultaneously generate electric power and treat wastewater. Both pure organic matter and real wastewater can be used as fuel to generate electric power and the substrate type can influence the microbial community structure. In the present study, rice straw, an important feedstock source in the world, was used as fuel after pretreatment with diluted acid method for a microbial fuel cell to obtain electric power. Moreover, the microbial community structures of anodic and cathodic biofilm and planktonic culturewere analyzed and compared to reveal the effect of niche on microbial community structure. Results The microbial fuel cell produced a maximum power density of 137.6 ± 15.5 mW/m2 at a COD concentration of 400 mg/L, which was further increased to 293.33 ± 7.89 mW/m2 through adjusting the electrolyte conductivity from 5.6 mS/cm to 17 mS/cm. Microbial community analysis showed reduction of the microbial diversities of the anodic biofilm and planktonic culture, whereas diversity of the cathodic biofilm was increased. Planktonic microbial communities were clustered closer to the anodic microbial communities compared to the cathodic biofilm. The differentiation in microbial community structure of the samples was caused by minor portion of the genus. The three samples shared the same predominant phylum of Proteobacteria. The abundance of exoelectrogenic genus was increased with Desulfobulbus as the shared most abundant genus; while the most abundant exoelectrogenic genus of Clostridium in the inoculum was reduced. Sulfate reducing bacteria accounted for large relative abundance in all the samples, whereas the relative abundance varied in different samples. Conclusion The results demonstrated that rice straw hydrolysate can be used as fuel for microbial fuel cells; microbial community structure differentiated depending on niches after microbial fuel cell operation; exoelectrogens were

  5. Mixed cellulose ester filter as a separator for air-diffusion cathode microbial fuel cells.

    PubMed

    Wang, Zejie; Lim, Bongsu

    2017-04-01

    Separator is important to prevent bio-contamination of the catalyst layer of air-diffusion cathode microbial fuel cells (MFCs). Mixed cellulose ester filter (MCEF) was examined as a separator for an air-cathode MFC in the present study. The MCEF-MFC produced a maximum power density of 780.7 ± 18.7 mW/m 2 , which was comparable to 770.9 ± 35.9 mW/m 2 of MFC with Nafion membrane (NFM) as a separator. Long-term examination demonstrated a more stable performance of the MCEF-MFC than NFM-MFC. After 25 cycles, the maximum voltage of the MCEF-MFC decreased by only 1.3% from 425.1 ± 4.3 mV (initial 5 cycles) to 419.5 ± 2.3 mV (last 5 cycles). However, it was decreased by 9.1% from 424.8 ± 5.7 to 386 ± 2.5 mV for the NFM-MFC. The coulombic efficiency (CE) of the MCEF-MFC did not change (from 3.11 ± 0.09% to 3.13 ± 0.02%), while it decreased by 9.12% from 3.18 ± 0.04% to 2.89 ± 0.02% for the NFM-MFC. The MCEF separator was with less biofouling than the NFM separator over 60 days' operation, which might be the reason for the more table long-term performance of the MCEF-MFC. The results demonstrated that MCEF was feasible as a separator to set up good-performing and cost-effective air-diffusion cathode MFC.

  6. N-type Cu2O doped activated carbon as catalyst for improving power generation of air cathode microbial fuel cells.

    PubMed

    Zhang, Xi; Li, Kexun; Yan, Pengyu; Liu, Ziqi; Pu, Liangtao

    2015-01-01

    A novel n-type Cu2O doped activated carbon (AC) air cathode (Cu/AC) was developed as an alternative to Pt electrode for oxygen reduction in microbial fuel cells (MFCs). The maximum power density of MFCs using this novel air cathode was as high as 1390±76mWm(-2), almost 59% higher than the bare AC air cathode. Specifically, the resistance including total resistance and charge transfer resistance significantly decreased comparing to the control. Tafel curve also showed the faster electro-transfer kinetics of Cu/AC with exchange current density of 1.03×10(-3)Acm(-2), which was 69% higher than the control. Ribbon-like Cu2O was deposited on the surface of AC with the mesopore surface area increasing. Cubic Cu2O crystals exclusively expose (111) planes with the interplanar crystal spacing of 2.48Å, which was the dominate active sites for oxygen reduction reaction (ORR). N-type Cu2O with oxygen vacancies played crucial roles in electrochemical catalytic activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Long-term performance of activated carbon air cathodes with different diffusion layer porosities in microbial fuel cells.

    PubMed

    Zhang, Fang; Pant, Deepak; Logan, Bruce E

    2011-12-15

    Activated carbon (AC) air-cathodes are inexpensive and useful alternatives to Pt-catalyzed electrodes in microbial fuel cells (MFCs), but information is needed on their long-term stability for oxygen reduction. AC cathodes were constructed with diffusion layers (DLs) with two different porosities (30% and 70%) to evaluate the effects of increased oxygen transfer on power. The 70% DL cathode initially produced a maximum power density of 1214±123 mW/m(2) (cathode projected surface area; 35±4 W/m(3) based on liquid volume), but it decreased by 40% after 1 year to 734±18 mW/m(2). The 30% DL cathode initially produced less power than the 70% DL cathode, but it only decreased by 22% after 1 year (from 1014±2 mW/m(2) to 789±68 mW/m(2)). Electrochemical tests were used to examine the reasons for the degraded performance. Diffusion resistance in the cathode was found to be the primary component of the internal resistance, and it increased over time. Replacing the cathode after 1 year completely restored the original power densities. These results suggest that the degradation in cathode performance was due to clogging of the AC micropores. These findings show that AC is a cost-effective material for oxygen reduction that can still produce ~750 mW/m(2) after 1 year. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. The performance of spinel bulk-like oxygen-deficient CoGa2O4 as an air-cathode catalyst in microbial fuel cell

    NASA Astrophysics Data System (ADS)

    Liu, Di; Mo, Xiaoping; Li, Kexun; Liu, Yi; Wang, Junjie; Yang, Tingting

    2017-08-01

    Nano spinel bulk-like CoGa2O4 prepared via a facile hydrothermal method is used as a high efficient electrochemical catalyst in activated carbon (AC) air-cathode microbial fuel cell (MFC). The maximum power density of the modified MFC is 1911 ± 49 mW m-2, 147% higher than the MFC of untreated AC cathode. Transmission electron microscope (TEM) and X-ray diffraction (XRD) exhibit the morphology and crystal structure of CoGa2O4. Rotating disk electrode (RDE) confirms the four-electron pathway at the cathode during the oxygen reduction reaction (ORR). Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) illustrate that the high rate oxygen vacancy exist in the CoGa2O4. The oxygen vacancy of CoGa2O4 plays an important role in catalytic activity. In a word, the prepared nano spinel bulk-like CoGa2O4 provides an alternative to the costly Pt in air-cathode for power output.

  9. Electricity generation of microbial fuel cell with waterproof breathable membrane cathode

    NASA Astrophysics Data System (ADS)

    Xing, Defeng; Tang, Yu; Mei, Xiaoxue; Liu, Bingfeng

    2015-12-01

    Simplification of fabrication and reduction of capital cost are important for scale-up and application of microbial electrochemical systems (MES). A fast and inexpensive method of making cathode was developed via assembling stainless steel mesh (SSM) with waterproof breathable membrane (WBM). Three assemble types of cathodes were fabricated; Pt@SSM/WBM (SSM as cathode skeleton, WBM as diffusion layer, platinum (Pt) catalyst applied on SSM), SSM/Pt@WBM and Pt@WBM. SSM/Pt@WBM cathode showed relatively preferable with long-term stability and favorable power output (24.7 W/m3). Compared to conventional cathode fabrication, air-cathode was made for 0.5 h. The results indicated that the novel fabrication method could remarkably reduce capital cost and simplify fabrication procedures with a comparable power output, making MFC more prospective for future application.

  10. Hollow-spherical Co/N-C nanoparticle as an efficient electrocatalyst used in air cathode microbial fuel cell.

    PubMed

    Yang, Tingting; Li, Kexun; Pu, Liangtao; Liu, Ziqi; Ge, Baochao; Pan, Yajun; Liu, Ying

    2016-12-15

    The hollow-spherical Co/N-C nanoparticle, which is synthesized via a simple hydrothermal reaction followed by heat treatment, is firstly used as electrocatalyst for oxygen reduction reaction (ORR) in air-cathode microbial fuel cell (MFC). The maximum power density of MFC with 10% Co/N-C air-cathode is as high as 2514±59mWm(-2), which is almost 174% higher than the control. The exchange current density (i0) of cathode equipped with 10% Co/N-C is 238% higher than that of untreated AC. While the total resistance of treated samples decreases from 13.017 to 10.255Ω. The intensity ratio of Raman D to G band (ID/IG) decreases from 0.93 (N-C) to 0.73 (Co/N-C), indicating the catalyst forms graphite structure. Both XRD and XPS testify that Co is bonded to N within graphitic sheets and serves as the active sites in ORR. The four-electron pathway of the Co/N-C also plays a crucial role in electrochemical catalytic activity. As a result, it can be expected that the as-synthesized Co/N-C, with extraordinary electro-catalytic performance towards ORR, will be a promising alternative to the state-of-the-art non-precious metal ORR electro-catalysts for electrochemical energy applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Self-Driven Desalination and Advanced Treatment of Wastewater in a Modularized Filtration Air Cathode Microbial Desalination Cell.

    PubMed

    Zuo, Kuichang; Wang, Zhen; Chen, Xi; Zhang, Xiaoyuan; Zuo, Jiaolan; Liang, Peng; Huang, Xia

    2016-07-05

    Microbial desalination cells (MDCs) extract organic energy from wastewater for in situ desalination of saline water. However, to desalinate salt water, traditional MDCs often require an anolyte (wastewater) and a catholyte (other synthetic water) to produce electricity. Correspondingly, the traditional MDCs also produced anode effluent and cathode effluent, and may produce a concentrate solution, resulting in a low production of diluate. In this study, nitrogen-doped carbon nanotube membranes and Pt carbon cloths were utilized as filtration material and cathode to fabricate a modularized filtration air cathode MDC (F-MDC). With real wastewater flowing from anode to cathode, and finally to the middle membrane stack, the diluate volume production reached 82.4%, with the removal efficiency of salinity and chemical oxygen demand (COD) reached 93.6% and 97.3% respectively. The final diluate conductivity was 68 ± 12 μS/cm, and the turbidity was 0.41 NTU, which were sufficient for boiler supplementary or industrial cooling. The concentrate production was only 17.6%, and almost all the phosphorus and salt, and most of the nitrogen were recovered, potentially allowing the recovery of nutrients and other chemicals. These results show the potential utility of the modularized F-MDC in the application of municipal wastewater advanced treatment and self-driven desalination.

  12. The addition of ortho-hexagon nano spinel Co3O4 to improve the performance of activated carbon air cathode microbial fuel cell.

    PubMed

    Ge, Baochao; Li, Kexun; Fu, Zhou; Pu, Liangtao; Zhang, Xi

    2015-11-01

    Commercial Co3O4 and ortho-hexagon spinel nano-Co3O4 (OHSNC) were doped in the AC at a different percentage (5%, 10% and 15%) to enhance the performance of microbial fuel cell (MFC). The maximum power density of MFC with 10% OHSNC doped cathode was 1500±14 mW m(-2), which was 97.36% and 41.24% higher than that with the bare AC air cathode and commercial Co3O4 respectively. The electrocatalytic behavior for their better performance was discussed in detail with the help of various structural and electrochemical techniques. The OHSNC was characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM). The results showed that the improved performance owed to the enhancement of both kinetics activity and the number of electron transfer in the ORR, and the internal resistance was largely reduced. Therefore, OHSNC was proved to be an excellent cathodic catalyst in AC air cathode MFC. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Electricity generation and nutrients removal from high-strength liquid manure by air-cathode microbial fuel cells.

    PubMed

    Lin, Hongjian; Wu, Xiao; Nelson, Chad; Miller, Curtis; Zhu, Jun

    2016-01-01

    Air-cathode microbial fuel cells (MFCs) are widely tested to recover electrical energy from waste streams containing organic matter. When high-strength wastewater, such as liquid animal manure, is used as a medium, inhibition on anode and cathode catalysts potentially impairs the effectiveness of MFC performance in power generation and pollutant removal. This study evaluated possible inhibitive effects of liquid swine manure components on MFC power generation, improved liquid manure-fed MFCs performance by pretreatment (dilution and selective adsorption), and modeled the kinetics of organic matter and nutrients removal kinetics. Parameters monitored included pH, conductivity, chemical oxygen demand (COD), volatile fatty acids (VFAs), total ammoniacal nitrogen (TAN), nitrite, nitrate, and phosphate concentrations. The removals of VFA and TAN were efficient, indicated by the short half-life times of 4.99 and 7.84 d, respectively. The mechanism for phosphate decrease was principally the salt precipitation on cathode, but the removal was incomplete after 42-d operation. MFC with an external resistor of 2.2 kΩ and fed with swine wastewater generated relatively small power (28.2 μW), energy efficiency (0.37%) and Coulombic efficiency (1.5%). Dilution of swine wastewater dramatically improved the power generation as the inhibitory effect was decreased. Zeolite and granular activated carbon were effective in the selective adsorption of ammonia or organic matter in swine wastewater, and so substantially improved the power generation, energy efficiency, and Coulombic efficiency. A smaller external resistor in the circuit was also observed to promote the organic matter degradation and thus to shorten the treatment time. Overall, air-cathode MFCs are promising for generating electrical power from livestock wastewater and meanwhile reducing the level of organic matter and nutrients.

  14. Efficient removal of nitrobenzene and concomitant electricity production by single-chamber microbial fuel cells with activated carbon air-cathode.

    PubMed

    Zhang, Enren; Wang, Feng; Zhai, Wenjing; Scott, Keith; Wang, Xu; Diao, Guowang

    2017-04-01

    Single-chamber microbial fuel cells (S-MFCs) with bio-anodes and activated carbon (AC) air-cathodes showed high nitrobenzene (NB) tolerance and NB removal with concomitant electricity production. The maximum power over 25Wm -3 could be obtained when S-MFCs were operated in the NB loading range of 1.2-6.2molm -3 d -1 , and stable electricity production over 13.7Wm -3 could be produced in a NB loading range of 1.2-14.7molm -3 d -1 . The present S-MFCs exhibited high NB removal performance with NB removal efficiency over 97% even when the NB loading rate was increased to 17.2molm -3 d -1 . The potential NB reduced product (i.e. aniline) could also be effectively removed from influents. The findings in this study means that single-chamber MFCs assembled with pre-enriched bio-anodes and AC air-cathodes could be developed as effective bio-electrochemical systems to remove NB from wastewaters and to harvest energy instead of consuming energy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Modeling and validation of single-chamber microbial fuel cell cathode biofilm growth and response to oxidant gas composition

    NASA Astrophysics Data System (ADS)

    Ou, Shiqi; Zhao, Yi; Aaron, Douglas S.; Regan, John M.; Mench, Matthew M.

    2016-10-01

    This work describes experiments and computational simulations to analyze single-chamber, air-cathode microbial fuel cell (MFC) performance and cathodic limitations in terms of current generation, power output, mass transport, biomass competition, and biofilm growth. Steady-state and transient cathode models were developed and experimentally validated. Two cathode gas mixtures were used to explore oxygen transport in the cathode: the MFCs exposed to a helium-oxygen mixture (heliox) produced higher current and power output than the group of MFCs exposed to air or a nitrogen-oxygen mixture (nitrox), indicating a dependence on gas-phase transport in the cathode. Multi-substance transport, biological reactions, and electrochemical reactions in a multi-layer and multi-biomass cathode biofilm were also simulated in a transient model. The transient model described biofilm growth over 15 days while providing insight into mass transport and cathodic dissolved species concentration profiles during biofilm growth. Simulation results predict that the dissolved oxygen content and diffusion in the cathode are key parameters affecting the power output of the air-cathode MFC system, with greater oxygen content in the cathode resulting in increased power output and fully-matured biomass.

  16. Modeling and validation of single-chamber microbial fuel cell cathode biofilm growth and response to oxidant gas composition

    DOE PAGES

    Ou, Shiqi; Zhao, Yi; Aaron, Douglas S.; ...

    2016-08-15

    This work describes experiments and computational simulations to analyze single-chamber, air-cathode microbial fuel cell (MFC) performance and cathodic limitations in terms of current generation, power output, mass transport, biomass competition, and biofilm growth. Steady-state and transient cathode models were developed and experimentally validated. Two cathode gas mixtures were used to explore oxygen transport in the cathode: the MFCs exposed to a helium-oxygen mixture (heliox) produced higher current and power output than the group of MFCs exposed to air or a nitrogen-oxygen mixture (nitrox), indicating a dependence on gas-phase transport in the cathode. Multi-substance transport, biological reactions, and electrochemical reactions inmore » a multi-layer and multi-biomass cathode biofilm were also simulated in a transient model. The transient model described biofilm growth over 15 days while providing insight into mass transport and cathodic dissolved species concentration profiles during biofilm growth. Lastly, simulation results predict that the dissolved oxygen content and diffusion in the cathode are key parameters affecting the power output of the air-cathode MFC system, with greater oxygen content in the cathode resulting in increased power output and fully-matured biomass.« less

  17. Single chamber microbial fuel cell with Ni-Co cathode

    NASA Astrophysics Data System (ADS)

    Włodarczyk, Barbara; Włodarczyk, Paweł P.; Kalinichenko, Antonina

    2017-10-01

    The possibility of wastewater treatment and the parallel energy production using the Ni-Co alloy as cathode catalyst for single chamber microbial fuel cells is presented in this research. The research included a preparation of catalyst and comparison of COD, NH4+ and NO3- reduction in the reactor without aeration, with aeration and with using a single chamber microbial fuel cell with Ni-Co cathode. The reduction time for COD with the use of microbial fuel cell with the Ni-Co catalyst is similar to the reduction time with aeration. The current density (2.4 A·m-2) and amount of energy (0.48 Wh) obtained in MFC is low, but the obtained amount of energy allows elimination of the energy needed for reactor aeration. It has been shown that the Ni-Co can be used as cathode catalyst in single chamber microbial fuel cells.

  18. Determination of Microbial Growth by Protein Assay in an Air-Cathode Single Chamber Microbial Fuel Cell.

    PubMed

    Li, Na; Kakarla, Ramesh; Moon, Jung Mi; Min, Booki

    2015-07-01

    Microbial fuel cells (MFCs) have gathered attention as a novel bioenergy technology to simultaneously treat wastewater with less sludge production than the conventional activated sludge system. In two different operations of the MFC and aerobic process, microbial growth was determined by the protein assay method and their biomass yields using real wastewater were compared. The biomass yield on the anode electrode of the MFC was 0.02 g-COD-cell/g- COD-substrate and the anolyte planktonic biomass was 0.14 g-COD-cell/g-COD-substrate. An MFC without anode electrode resulted in the biomass yield of 0.07 ± 0.03 g-COD-cell/g-COD-substrate, suggesting that oxygen diffusion from the cathode possibly supported the microbial growth. In a comparative test, the biomass yield under aerobic environment was 0.46 ± 0.07 g-COD-cell/g-COD-substrate, which was about 3 times higher than the total biomass value in the MFC operation.

  19. Porous nitrogen-doped carbon nanosheet on graphene as metal-free catalyst for oxygen reduction reaction in air-cathode microbial fuel cells.

    PubMed

    Wen, Qing; Wang, Shaoyun; Yan, Jun; Cong, Lijie; Chen, Ye; Xi, Hongyuan

    2014-02-01

    Porous nitrogen-doped carbon nanosheet on graphene (PNCN) was used as an alternative cathode catalyst for oxygen reduction reaction (ORR) in air-cathode microbial fuel cells (MFCs). Here we report a novel, low-cost, scalable, synthetic method for preparation of PNCN via the carbonization of graphite oxide-polyaniline hybrid (GO-PANI), subsequently followed by KOH activation treatment. Due to its high concentration of nitrogen and high specific surface area, PNCN exhibited an excellent catalytic activity for ORR. As a result, the maximum power density of 1159.34mWm(-2) obtained with PNCN catalyst was higher than that of Pt/C catalyst (858.49mWm(-2)) in a MFC. Therefore, porous nitrogen-doped carbon nanosheet could be a good alternative to Pt catalyst in MFCs. © 2013.

  20. Mitigating external and internal cathode fouling using a polymer bonded separator in microbial fuel cells.

    PubMed

    Yang, Wulin; Rossi, Ruggero; Tian, Yushi; Kim, Kyoung-Yeol; Logan, Bruce E

    2018-02-01

    Microbial fuel cell (MFC) cathodes rapidly foul when treating domestic wastewater, substantially reducing power production over time. Here a wipe separator was chemically bonded to an activated carbon air cathode using polyvinylidene fluoride (PVDF) to mitigate cathode fouling and extend cathode performance over time. MFCs with separator-bonded cathodes produced a maximum power density of 190 ± 30 mW m -2 after 2 months of operation using domestic wastewater, which was ∼220% higher than controls (60 ± 50 mW m -2 ) with separators that were not chemically bonded to the cathode. Less biomass (protein) was measured on the bonded separator surface than the non-bonded separator, indicating chemical bonding reduced external bio-fouling. Salt precipitation that contributed to internal fouling was also reduced using separator-bonded cathodes. Overall, the separator-bonded cathodes showed better performance over time by mitigating both external bio-fouling and internal salt fouling. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Characterization of bacterial and archaeal communities in air-cathode microbial fuel cells, open circuit and sealed-off reactors.

    PubMed

    Shehab, Noura; Li, Dong; Amy, Gary L; Logan, Bruce E; Saikaly, Pascal E

    2013-11-01

    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.

  2. Bio-electrochemical characterization of air-cathode microbial fuel cells with microporous polyethylene/silica membrane as separator.

    PubMed

    Kircheva, Nina; Outin, Jonathan; Perrier, Gérard; Ramousse, Julien; Merlin, Gérard; Lyautey, Emilie

    2015-12-01

    The aim of this work was to study the behavior over time of a separator made of a low-cost and non-selective microporous polyethylene membrane (RhinoHide®) in an air-cathode microbial fuel cell with a reticulated vitreous carbon foam bioanode. Performances of the microporous polyethylene membrane (RhinoHide®) were compared with Nafion®-117 as a cationic exchange membrane. A non-parametric test (Mann-Whitney) done on the different sets of coulombic or energy efficiency data showed no significant difference between the two types of tested membrane (p<0.05). Volumetric power densities were ranging from 30 to 90 W·m(-3) of RVC foam for both membranes. Similar amounts of biomass were observed on both sides of the polyethylene membrane illustrating bacterial permeability of this type of separator. A monospecific denitrifying population on cathodic side of RhinoHide® membrane has been identified. Electrochemical impedance spectroscopy (EIS) was used at OCV conditions to characterize electrochemical behavior of MFCs by equivalent electrical circuit fitted on both Nyquist and Bode plots. Resistances and pseudo-capacitances from EIS analyses do not differ in such a way that the nature of the membrane could be considered as responsible. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Anolyte recirculation effects in buffered and unbuffered single-chamber air-cathode microbial fuel cells.

    PubMed

    Zhang, Liang; Zhu, Xun; Kashima, Hiroyuki; Li, Jun; Ye, Ding-Ding; Liao, Qiang; Regan, John M

    2015-03-01

    Two identical microbial fuel cells (MFCs) with a floating air-cathode were operated under either buffered (MFC-B) or bufferless (MFC-BL) conditions to investigate anolyte recirculation effects on enhancing proton transfer. With an external resistance of 50 Ω and recirculation rate of 1.0 ml/min, MFC-BL had a 27% lower voltage (9.7% lower maximal power density) but a 64% higher Coulombic efficiency (CE) than MFC-B. MFC-B had a decreased voltage output, batch time, and CE with increasing recirculation rate resulting from more oxygen transfer into the anode. However, increasing the recirculation rate within a low range significantly enhanced proton transfer in MFC-BL, resulting in a higher voltage output, a longer batch time, and a higher CE. A further increase in recirculation rate decreased the batch time and CE of MFC-BL due to excess oxygen transfer into anode outweighing the proton-transfer benefits. The unbuffered MFC had an optimal recirculation rate of 0.35 ml/min. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Microbial Fuel Cell Performance with a Pressurized Cathode Chamber

    USDA-ARS?s Scientific Manuscript database

    Microbial fuel cell (MFC) power densities are often constrained by the oxygen reduction reaction rate on the cathode electrode. One important factor for this is the normally low solubility of oxygen in the aqueous cathode solution creating mass transport limitations, which hinder oxygen reduction a...

  5. Activated carbon derived from chitosan as air cathode catalyst for high performance in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Zhao, Yong; Li, Kexun; Wang, Zhong; Tian, Pei; Liu, Di; Yang, Tingting; Wang, Junjie

    2018-02-01

    Chitosan with rich of nitrogen is used as carbon precursor to synthesis activated carbon through directly heating method in this study. The obtained carbon is activated by different amount of KOH at different temperatures, and then prepared as air cathodes for microbial fuel cells. Carbon sample treated with double amount of KOH at 850 °C exhibits maximum power density (1435 ± 46 mW m-2), 1.01 times improved, which ascribes to the highest total surface area, moderate micropore and mesoporous structure and the introduction of nitrogen. The electrochemical impedance spectroscopy and powder resistivity state that carbon treated with double amount of KOH at 850 °C possesses lower resistance. The other electrochemical measurements demonstrate that the best kinetic activity make the above treated sample to show the best oxygen reduction reaction activity. Besides, the degree of graphitization of samples increases with the activated temperature increasing, which is tested by Raman. According to elemental analysis and X-ray photoelectron spectroscopy, all chitosan samples are nitrogen-doped carbon, and high content nitrogen (pyridinic-N) improves the electrochemical activity of carbon treated with KOH at 850 °C. Thus, carbon materials derived from chitosan would be an optimized catalyst for oxygen reduction reaction in microbial fuel cell.

  6. The excellent performance of nest-like oxygen-deficient Cu1.5Mn1.5O4 applied in activated carbon air-cathode microbial fuel cell.

    PubMed

    Wang, Junjie; Tian, Pei; Li, Kexun; Ge, Baochao; Liu, Di; Liu, Yi; Yang, Tingting; Ren, Rong

    2016-12-01

    This study investigated the performance of nano spinel nest-like oxygen-deficient Cu 1.5 Mn 1.5 O 4 doping activated carbon (AC) as air cathode in microbial fuel cell (MFC). The Cu 1.5 Mn 1.5 O 4 was synthesized via hydrothermal method and subsequent annealed. The maximum power density (MPD) of MFC with oxygen-deficient Cu 1.5 Mn 1.5 O 4 modified cathode was 1928±18mWm -2 , which was 1.53 times higher than the bare cathode. The electrochemical studies showed that Cu 1.5 Mn 1.5 O 4 doping AC exhibited higher kinetic activity and lower resistance. The mechanism of oxygen reduction for the catalyst was a four electron pathway. The oxygen deficient of Cu 1.5 Mn 1.5 O 4 played an important role in catalytic activity. So Cu 1.5 Mn 1.5 O 4 would be an excellent promising catalyst for ORR in MFC. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Polyaniline/β-MnO2 nanocomposites as cathode electrocatalyst for oxygen reduction reaction in microbial fuel cells.

    PubMed

    Zhou, Xinxing; Xu, Yunzhi; Mei, Xiaojie; Du, Ningjie; Jv, Rongmao; Hu, Zhaoxia; Chen, Shouwen

    2018-05-01

    An efficient and inexpensive catalyst for oxygen reduction reaction (ORR), polyaniline (PANI) and β-MnO 2 nanocomposites (PANI/β-MnO 2 ), was developed for air-cathode microbial fuel cells (MFCs). The PANI/β-MnO 2 , β-MnO 2 , PANI and β-MnO 2 mixture modified graphite felt electrodes were fabricated as air-cathodes in double-chambered MFCs and their cell performances were compared. At a dosage of 6 mg cm -2 , the maximum power densities of MFCs with PANI/β-MnO 2 , β-MnO 2 , PANI and β-MnO 2 mixture cathodes reached 248, 183 and 204 mW m -2 , respectively, while the cathode resistances were 38.4, 45.5 and 42.3 Ω, respectively, according to impedance analysis. Weak interaction existed between the rod-like β-MnO 2 and surficial growth granular PANI, this together with the larger specific surface area and PANI electric conducting nature enhanced the electrochemical activity for ORR and improved the power generation. The PANI/β-MnO 2 nanocomposites are a promising cathode catalyst for practical application of MFCs. Copyright © 2018. Published by Elsevier Ltd.

  8. Hydrothermal Synthesis of Nanostructured Manganese Oxide as Cathodic Catalyst in a Microbial Fuel Cell Fed with Leachate

    PubMed Central

    Haoran, Yuan; Lifang, Deng; Tao, Lu; Yong, Chen

    2014-01-01

    Much effort has been devoted to the synthesis of novel nanostructured MnO2 materials because of their unique properties and potential applications as cathode catalyst in Microbial fuel cell. Hybrid MnO2 nanostructures were fabricated by a simple hydrothermal method in this study. Their crystal structures, morphology, and electrochemical characters were carried out by FESEM, N2-adsorption-desorption, and CV, indicating that the hydrothermally synthesized MnO2 (HSM) was structured by nanorods of high aspect ratio and multivalve nanoflowers and more positive than the naturally synthesized MnO2 (NSM), accompanied by a noticeable increase in oxygen reduction peak current. When the HSM was employed as the cathode catalyst in air-cathode MFC which fed with leachate, a maximum power density of 119.07 mW/m2 was delivered, 64.68% higher than that with the NSM as cathode catalyst. Furthermore, the HSM via a 4-e pathway, but the NSM via a 2-e pathway in alkaline solution, and as 4-e pathway is a more efficient oxygen reduction reaction, the HSM was more positive than NSM. Our study provides useful information on facile preparation of cost-effective cathodic catalyst in air-cathode MFC for wastewater treatment. PMID:24723824

  9. Comparative analysis of microbial community between different cathode systems of microbial fuel cells for denitrification.

    PubMed

    Li, Chao; Xu, Ming; Lu, Yi; Fang, Fang; Cao, Jiashun

    2016-01-01

    Two types of cathodic biofilm in microbial fuel cells (MFC) were established for comparison on their performance and microbial communities. Complete autotrophic simultaneous nitrification and denitrification (SND) without organics addition was achieved in nitrifying-MFC (N-MFC) with a total nitrogen (TN) removal rate of 0.35 mg/(L·h), which was even higher than that in denitrifying-MFC (D-MFC) at same TN level. Integrated denaturing gradient gel electrophoresis analysis based on both 16S rRNA and nirK genes showed that Alpha-, Gammaproteobacteria were the main denitrifier communities. Some potential autotrophic denitrifying bacteria which can use electrons and reducing power from cathodes, such as Shewanella oneidensis, Shewanella loihica, Pseudomonas aeruginosa, Starkeya novella and Rhodopseudomonas palustris were identified and selectively enriched on cathode biofilms. Further, relative abundance of denitrifying bacteria characterized by nirK/16S ratios was much higher in biofilm than suspended sludge according to real-time polymerase chain reaction. The highest enrichment efficiency for denitrifiers was obtained in N-MFC cathode biofilms, which confirmed autotrophic denitrifying bacteria enrichment is the key factor for a D-MFC system.

  10. Sustainable design of high-performance microsized microbial fuel cell with carbon nanotube anode and air cathode.

    PubMed

    Mink, Justine E; Hussain, Muhammad Mustafa

    2013-08-27

    Microbial fuel cells (MFCs) are a promising alternative energy source that both generates electricity and cleans water. Fueled by liquid wastes such as wastewater or industrial wastes, the microbial fuel cell converts waste into energy. Microsized MFCs are essentially miniature energy harvesters that can be used to power on-chip electronics, lab-on-a-chip devices, and/or sensors. As MFCs are a relatively new technology, microsized MFCs are also an important rapid testing platform for the comparison and introduction of new conditions or materials into macroscale MFCs, especially nanoscale materials that have high potential for enhanced power production. Here we report a 75 μL microsized MFC on silicon using CMOS-compatible processes and employ a novel nanomaterial with exceptional electrochemical properties, multiwalled carbon nanotubes (MWCNTs), as the on-chip anode. We used this device to compare the usage of the more commonly used but highly expensive anode material gold, as well as a more inexpensive substitute, nickel. This is the first anode material study done using the most sustainably designed microsized MFC to date, which utilizes ambient oxygen as the electron acceptor with an air cathode instead of the chemical ferricyanide and without a membrane. Ferricyanide is unsustainable, as the chemical must be continuously refilled, while using oxygen, naturally found in air, makes the device mobile and is a key step in commercializing this for portable technology such as lab-on-a-chip for point-of-care diagnostics. At 880 mA/m(2) and 19 mW/m(2) the MWCNT anode outperformed the others in both current and power densities with between 6 and 20 times better performance. All devices were run for over 15 days, indicating a stable and high-endurance energy harvester already capable of producing enough power for ultra-low-power electronics and able to consistently power them over time.

  11. Air cathode structure manufacture

    DOEpatents

    Momyer, William R.; Littauer, Ernest L.

    1985-01-01

    An improved air cathode structure for use in primary batteries and the like. The cathode structure includes a matrix active layer, a current collector grid on one face of the matrix active layer, and a porous, nonelectrically conductive separator on the opposite face of the matrix active layer, the collector grid and separator being permanently bonded to the matrix active layer. The separator has a preselected porosity providing low IR losses and high resistance to air flow through the matrix active layer to maintain high bubble pressure during operation of the battery. In the illustrated embodiment, the separator was formed of porous polypropylene. A thin hydrophobic film is provided, in the preferred embodiment, on the current collecting metal grid.

  12. Scalable air cathode microbial fuel cells using glass fiber separators, plastic mesh supporters, and graphite fiber brush anodes.

    PubMed

    Zhang, Xiaoyuan; Cheng, Shaoan; Liang, Peng; Huang, Xia; Logan, Bruce E

    2011-01-01

    The combined use of brush anodes and glass fiber (GF1) separators, and plastic mesh supporters were used here for the first time to create a scalable microbial fuel cell architecture. Separators prevented short circuiting of closely-spaced electrodes, and cathode supporters were used to avoid water gaps between the separator and cathode that can reduce power production. The maximum power density with a separator and supporter and a single cathode was 75 ± 1 W/m(3). Removing the separator decreased power by 8%. Adding a second cathode increased power to 154 ± 1 W/m(3). Current was increased by connecting two MFCs connected in parallel. These results show that brush anodes, combined with a glass fiber separator and a plastic mesh supporter, produce a useful MFC architecture that is inherently scalable due to good insulation between the electrodes and a compact architecture. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. Electricity generation using an air-cathode single chamber microbial fuel cell in the presence and absence of a proton exchange membrane.

    PubMed

    Liu, Hong; Logan, Bruce E

    2004-07-15

    Microbial fuel cells (MFCs) are typically designed as a two-chamber system with the bacteria in the anode chamber separated from the cathode chamber by a polymeric proton exchange membrane (PEM). Most MFCs use aqueous cathodes where water is bubbled with air to provide dissolved oxygen to electrode. To increase energy output and reduce the cost of MFCs, we examined power generation in an air-cathode MFC containing carbon electrodes in the presence and absence of a polymeric proton exchange membrane (PEM). Bacteria present in domestic wastewater were used as the biocatalyst, and glucose and wastewater were tested as substrates. Power density was found to be much greater than typically reported for aqueous-cathode MFCs, reaching a maximum of 262 +/- 10 mW/m2 (6.6 +/- 0.3 mW/L; liquid volume) using glucose. Removing the PEM increased the maximum power density to 494 +/- 21 mW/m2 (12.5 +/- 0.5 mW/L). Coulombic efficiency was 40-55% with the PEM and 9-12% with the PEM removed, indicating substantial oxygen diffusion into the anode chamber in the absence of the PEM. Power output increased with glucose concentration according to saturation-type kinetics, with a half saturation constant of 79 mg/L with the PEM-MFC and 103 mg/L in the MFC without a PEM (1000 omega resistor). Similar results on the effect of the PEM on power density were found using wastewater, where 28 +/- 3 mW/m2 (0.7 +/- 0.1 mW/L) (28% Coulombic efficiency) was produced with the PEM, and 146 +/- 8 mW/m2 (3.7 +/- 0.2 mW/L) (20% Coulombic efficiency) was produced when the PEM was removed. The increase in power output when a PEM was removed was attributed to a higher cathode potential as shown by an increase in the open circuit potential. An analysis based on available anode surface area and maximum bacterial growth rates suggests that mediatorless MFCs may have an upper order-of-magnitude limit in power density of 10(3) mW/m2. A cost-effective approach to achieving power densities in this range will likely

  14. Full cell simulation and the evaluation of the buffer system on air-cathode microbial fuel cell

    NASA Astrophysics Data System (ADS)

    Ou, Shiqi; Kashima, Hiroyuki; Aaron, Douglas S.; Regan, John M.; Mench, Matthew M.

    2017-04-01

    This paper presents a computational model of a single chamber, air-cathode MFC. The model considers losses due to mass transport, as well as biological and electrochemical reactions, in both the anode and cathode half-cells. Computational fluid dynamics and Monod-Nernst analysis are incorporated into the reactions for the anode biofilm and cathode Pt catalyst and biofilm. The integrated model provides a macro-perspective of the interrelation between the anode and cathode during power production, while incorporating microscale contributions of mass transport within the anode and cathode layers. Model considerations include the effects of pH (H+/OH- transport) and electric field-driven migration on concentration overpotential, effects of various buffers and various amounts of buffer on the pH in the whole reactor, and overall impacts on the power output of the MFC. The simulation results fit the experimental polarization and power density curves well. Further, this model provides insight regarding mass transport at varying current density regimes and quantitative delineation of overpotentials at the anode and cathode. Overall, this comprehensive simulation is designed to accurately predict MFC performance based on fundamental fluid and kinetic relations and guide optimization of the MFC system.

  15. Enhanced bioelectricity generation of air-cathode buffer-free microbial fuel cells through short-term anolyte pH adjustment.

    PubMed

    Ren, Yueping; Chen, Jinli; Li, Xiufen; Yang, Na; Wang, Xinhua

    2018-04-01

    Short-term initial anolyte pH adjustment can relieve the performance deterioration of the single-chamber air-cathode buffer-free microbial fuel cell (BFMFC) caused by anolyte acidification. Adjusting the initial anolyte pH to 9 in 5 running cycles is the optimum strategy. The relative abundance of the electrochemically active Geobacter in the KCl-pH9-MFC anode biofilm increased from 59.01% to 75.13% after the short-term adjustment. The maximum power density (P max ) of the KCl-pH9-MFC was elevated from 316.4mW·m -2 to 511.6mW·m -2 , which was comparable with that of the PBS-MFC. And, after the short-term adjusting, new equilibrium between the anolyte pH and the anode biofilm electrochemical activity has been established in the BFMFC, which ensured the sustainability of the improved bioelectricity generation performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Air breathing cathodes for microbial fuel cell using Mn-, Fe-, Co- and Ni-containing platinum group metal-free catalysts

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kodali, Mounika; Santoro, Carlo; Serov, Alexey

    Here we discuss the oxygen reduction reaction (ORR) is one of the major factors that is limiting the overall performance output of microbial fuel cells (MFC). In this study, Platinum Group Metal-free (PGM-free) ORR catalysts based on Fe, Co, Ni, Mn and the same precursor (Aminoantipyrine, AAPyr) were synthesized using identical sacrificial support method (SSM). The catalysts were investigated for their electrochemical performance, and then integrated into an air-breathing cathode to be tested in “clean” environment and in a working microbial fuel cell (MFC). Their performances were also compared to activated carbon (AC) based cathode under similar conditions. Results showedmore » that the addition of Mn, Fe, Co and Ni to AAPyr increased the performances compared to AC. Fe-AAPyr showed the highest open circuit potential (OCP) that was 0.307 ± 0.001 V (vs. Ag/AgCl) and the highest electrocatalytic activity at pH 7.5. On the contrary, AC had an OCP of 0.203 ± 0.002 V (vs. Ag/AgCl) and had the lowest electrochemical activity. In MFC, Fe-AAPyr also had the highest output of 251 ± 2.3 μWcm –2, followed by Co-AAPyr with 196 ± 1.5 μWcm –2, Ni-AAPyr with 171 ± 3.6 μWcm –2, Mn-AAPyr with 160 ± 2.8 μWcm –2 and AC 129 ± 4.2 μWcm –2. The best performing catalyst (Fe-AAPyr) was then tested in MFC with increasing solution conductivity from 12.4 mScm –1 to 63.1 mScm –1. A maximum power density of 482 ± 5 μWcm –2 was obtained with increasing solution conductivity, which is one of the highest values reported in the field.« less

  17. Air breathing cathodes for microbial fuel cell using Mn-, Fe-, Co- and Ni-containing platinum group metal-free catalysts

    DOE PAGES

    Kodali, Mounika; Santoro, Carlo; Serov, Alexey; ...

    2017-02-07

    Here we discuss the oxygen reduction reaction (ORR) is one of the major factors that is limiting the overall performance output of microbial fuel cells (MFC). In this study, Platinum Group Metal-free (PGM-free) ORR catalysts based on Fe, Co, Ni, Mn and the same precursor (Aminoantipyrine, AAPyr) were synthesized using identical sacrificial support method (SSM). The catalysts were investigated for their electrochemical performance, and then integrated into an air-breathing cathode to be tested in “clean” environment and in a working microbial fuel cell (MFC). Their performances were also compared to activated carbon (AC) based cathode under similar conditions. Results showedmore » that the addition of Mn, Fe, Co and Ni to AAPyr increased the performances compared to AC. Fe-AAPyr showed the highest open circuit potential (OCP) that was 0.307 ± 0.001 V (vs. Ag/AgCl) and the highest electrocatalytic activity at pH 7.5. On the contrary, AC had an OCP of 0.203 ± 0.002 V (vs. Ag/AgCl) and had the lowest electrochemical activity. In MFC, Fe-AAPyr also had the highest output of 251 ± 2.3 μWcm –2, followed by Co-AAPyr with 196 ± 1.5 μWcm –2, Ni-AAPyr with 171 ± 3.6 μWcm –2, Mn-AAPyr with 160 ± 2.8 μWcm –2 and AC 129 ± 4.2 μWcm –2. The best performing catalyst (Fe-AAPyr) was then tested in MFC with increasing solution conductivity from 12.4 mScm –1 to 63.1 mScm –1. A maximum power density of 482 ± 5 μWcm –2 was obtained with increasing solution conductivity, which is one of the highest values reported in the field.« less

  18. Manganese dioxide as a new cathode catalyst in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Hu, Boxun; Suib, Steven; Lei, Yu; Li, Baikun

    This study focused on manganese oxides with a cryptomelane-type octahedral molecular sieve (OMS-2) structure to replace platinum as a cathode catalyst in microbial fuel cells (MFCs). Undoped (ud-OSM-2) and three catalysts doped with cobalt (Co-OMS-2), copper (Cu-OMS-2), and cerium (Ce-OMS-2) to enhance their catalytic performances were investigated. The novel OMS-2 cathodes were examined in granular activated carbon MFC (GACMFC) with sodium acetate as the anode reagent and oxygen in air as the cathode reagent. The results showed that after 400 h of operation, the Co-OMS-2 and Cu-OMS-2 exhibited good catalytic performance in an oxygen reduction reaction (ORR). The voltage of the Co-OMS-2 GACMFC was 217 mV, and the power density was 180 mW m -2. The voltage of the Cu-OMS-2 GACMFC was 214 mV and the power density was 165 mW m -2. The internal resistance (R in) of the OMS-2 GACMFCs (18 ± 1 Ω) was similar to that of the platinum GACMFCs (17 Ω). Furthermore, the degradation rates of organic substrates in the OMS-2 GACMFCs were twice those in the platinum GACMFCs, which enhance their wastewater treatment efficiencies. This study indicated that using OMS-2 manganese oxides to replace platinum as a cathodic catalyst enhances power generation, increases contaminant removal, and substantially reduces the cost of MFCs.

  19. Full cell simulation and the evaluation of the buffer system on air-cathode microbial fuel cell

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ou, Shiqi; Kashima, Hiroyuki; Aaron, Douglas S.

    This paper presents a computational model of a single chamber, air-cathode MFC. The model considers losses due to mass transport, as well as biological and electrochemical reactions, in both the anode and cathode half-cells. Computational fluid dynamics and Monod-Nernst analysis are incorporated into the reactions for the anode biofilm and cathode Pt catalyst and biofilm. The integrated model provides a macro-perspective of the interrelation between the anode and cathode during power production, while incorporating microscale contributions of mass transport within the anode and cathode layers. Model considerations include the effects of pH (H +/OH – transport) and electric field-driven migrationmore » on concentration overpotential, effects of various buffers and various amounts of buffer on the pH in the whole reactor, and overall impacts on the power output of the MFC. The simulation results fit the experimental polarization and power density curves well. Further, this model provides insight regarding mass transport at varying current density regimes and quantitative delineation of overpotentials at the anode and cathode. Altogether, this comprehensive simulation is designed to accurately predict MFC performance based on fundamental fluid and kinetic relations and guide optimization of the MFC system.« less

  20. Full cell simulation and the evaluation of the buffer system on air-cathode microbial fuel cell

    DOE PAGES

    Ou, Shiqi; Kashima, Hiroyuki; Aaron, Douglas S.; ...

    2017-02-23

    This paper presents a computational model of a single chamber, air-cathode MFC. The model considers losses due to mass transport, as well as biological and electrochemical reactions, in both the anode and cathode half-cells. Computational fluid dynamics and Monod-Nernst analysis are incorporated into the reactions for the anode biofilm and cathode Pt catalyst and biofilm. The integrated model provides a macro-perspective of the interrelation between the anode and cathode during power production, while incorporating microscale contributions of mass transport within the anode and cathode layers. Model considerations include the effects of pH (H +/OH – transport) and electric field-driven migrationmore » on concentration overpotential, effects of various buffers and various amounts of buffer on the pH in the whole reactor, and overall impacts on the power output of the MFC. The simulation results fit the experimental polarization and power density curves well. Further, this model provides insight regarding mass transport at varying current density regimes and quantitative delineation of overpotentials at the anode and cathode. Altogether, this comprehensive simulation is designed to accurately predict MFC performance based on fundamental fluid and kinetic relations and guide optimization of the MFC system.« less

  1. Battery with modular air cathode and anode cage

    DOEpatents

    Niksa, Marilyn J.; Pohto, Gerald R.; Lakatos, Leslie K.; Wheeler, Douglas J.; Niksa, Andrew J.; Schue, Thomas J.

    1987-01-01

    A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom.

  2. Battery with modular air cathode and anode cage

    DOEpatents

    Niksa, Marilyn J.; Pohto, Gerald R.; Lakatos, Leslie K.; Wheeler, Douglas J.; Niksa, Andrew J.; Schue, Thomas J.; Turk, Thomas R.

    1988-01-01

    A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom.

  3. Power generation using spinel manganese-cobalt oxide as a cathode catalyst for microbial fuel cell applications.

    PubMed

    Mahmoud, Mohamed; Gad-Allah, Tarek A; El-Khatib, K M; El-Gohary, Fatma

    2011-11-01

    This study focused on the use of spinel manganese-cobalt (Mn-Co) oxide, prepared by a solid state reaction, as a cathode catalyst to replace platinum in microbial fuel cells (MFCs) applications. Spinel Mn-Co oxides, with an Mn/Co atomic ratios of 0.5, 1, and 2, were prepared and examined in an air cathode MFCs which was fed with a molasses-laden synthetic wastewater and operated in batch mode. Among the three Mn-Co oxide cathodes and after 300 h of operation, the Mn-Co oxide catalyst with Mn/Co atomic ratio of 2 (MnCo-2) exhibited the highest power generation 113 mW/m2 at cell potential of 279 mV, which were lower than those for the Pt catalyst (148 mW/m2 and 325 mV, respectively). This study indicated that using spinel Mn-Co oxide to replace platinum as a cathodic catalyst enhances power generation, increases contaminant removal, and substantially reduces the cost of MFCs. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Immobilization of a Metal-Nitrogen-Carbon Catalyst on Activated Carbon with Enhanced Cathode Performance in Microbial Fuel Cells.

    PubMed

    Yang, Wulin; Logan, Bruce E

    2016-08-23

    Applications of microbial fuel cells (MFCs) are limited in part by low power densities mainly due to cathode performance. Successful immobilization of an Fe-N-C co-catalyst on activated carbon (Fe-N-C/AC) improved the oxygen reduction reaction to nearly a four-electron transfer, compared to a twoelectron transfer achieved using AC. With acetate as the fuel, the maximum power density was 4.7±0.2 W m(-2) , which is higher than any previous report for an air-cathode MFC. With domestic wastewater as a fuel, MFCs with the Fe-N-C/AC cathode produced up to 0.8±0.03 W m(-2) , which was twice that obtained with a Pt-catalyzed cathode. The use of this Fe-N-C/AC catalyst can therefore substantially increase power production, and enable broader applications of MFCs for renewable electricity generation using waste materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Cathodes for lithium-air battery cells with acid electrolytes

    DOEpatents

    Xing, Yangchuan; Huang, Kan; Li, Yunfeng

    2016-07-19

    In various embodiments, the present disclosure provides a layered metal-air cathode for a metal-air battery. Generally, the layered metal-air cathode comprises an active catalyst layer, a transition layer bonded to the active catalyst layer, and a backing layer bonded to the transition layer such that the transition layer is disposed between the active catalyst layer and the backing layer.

  6. Cathodic and anodic biofilms in Single Chamber Microbial Fuel Cells.

    PubMed

    Cristiani, P; Carvalho, M L; Guerrini, E; Daghio, M; Santoro, C; Li, B

    2013-08-01

    The oxygen reduction due to microaerophilic biofilms grown on graphite cathodes (biocathodes) in Single Chamber Microbial Fuel Cells (SCMFCs) is proved and analysed in this paper. Pt-free cathode performances are compared with those of different platinum-loaded cathodes, before and after the biofilm growth. Membraneless SCMFCs were operating in batch-mode, filled with wastewater. A substrate (fuel) of sodium acetate (0.03 M) was periodically added and the experiment lasted more than six months. A maximum of power densities, up to 0.5 W m(-2), were reached when biofilms developed on the electrodes and the cathodic potential decreased (open circuit potential of 50-200 mV vs. SHE). The power output was almost constant with an acetate concentration of 0.01-0.05 M and it fell down when the pH of the media exceeded 9.5, independently of the Pt-free/Pt-loading at the cathodes. Current densities varied in the range of 1-5 Am(-2) (cathode area of 5 cm(2)). Quasi-stationary polarization curves performed with a three-electrode configuration on cathodic and anodic electrodes showed that the anodic overpotential, more than the cathodic one, may limit the current density in the SCMFCs for a long-term operation. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Acidic and alkaline pretreatments of activated carbon and their effects on the performance of air-cathodes in microbial fuel cells.

    PubMed

    Wang, Xin; Gao, Ningshengjie; Zhou, Qixing; Dong, Heng; Yu, Hongbing; Feng, Yujie

    2013-09-01

    Activated carbon (AC) is a high performing and cost effective catalyst for oxygen reduction reactions (ORRs) of air-cathodes in microbial fuel cells (MFCs). Acidic (HNO3) and alkaline (KOH) pretreatments on AC at low temperature (85°C) are conducted to enhance the performance of MFCs. The alkaline pretreatment increased the power density by 16% from 804±70 to 957±31 mW m(-2), possibly due to the decrease of ohmic resistance (from 20.58 to 19.20 Ω) and the increase of ORR activities provided by the adsorbed hydroxide ion and extra micropore area/volume after alkaline pretreatment. However, acidic pretreatment decreased the power output to 537±36 mW m(-2), which can be mainly attributed to the corrosion by adsorbed proton at the interface of AC powder and stainless steel mesh and the decreased pore area. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Effects of nitrate and sulfate on the performance and bacterial community structure of membrane-less single-chamber air-cathode microbial fuel cells.

    PubMed

    Seo, Yoonjoo; Kang, Hyemin; Chang, Sumin; Lee, Yun-Yeong; Cho, Kyung-Suk

    2018-01-02

    Membrane-less, single-chamber, air-cathode, microbial fuel cells (ML-SC MFCs) have attracted attention as being suitable for wastewater treatment. In this study, the effects of nitrate and sulfate on the performance of ML-SC MFCs and their bacterial structures were evaluated. The maximum power density increased after nitrate addition from 8.6 mW·m -2 to 14.0 mW·m -2 , while it decreased after sulfate addition from 11.5 mW·m -2 to 7.7 mW·m -2 . The chemical oxygen demand removal efficiencies remained at more than 90% regardless of the nitrate or sulfate additions. The nitrate was removed completely (93.0%) in the ML-SC MFC, while the sulfate removal efficiency was relatively low (17.6%). Clostridium (23.1%), Petrimonas (20.0%), and unclassified Rhodocyclaceae (6.2%) were dominant on the anode before the addition of nitrate or sulfate. After the addition of nitrate, Clostridium was still the most dominant on the anode (23.6%), but Petrimonas significantly decreased (6.0%) and unclassified Rhodocyclaceae increased (17.1%). After the addition of sulfate, the amount of Clostridium almost doubled in the composition on the anode (43.2%), while Petrimonas decreased (5.5%). The bacterial community on the cathode was similar to that on the anode after the addition of nitrate. However, Desulfovibrio was remarkably dominant on the cathode (32.9%) after the addition of sulfate. These results promote a deeper understanding of the effects of nitrate or sulfate on the ML-SC MFCs' performance and their bacterial community.

  9. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells

    EPA Science Inventory

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2...

  10. Substantial Humic Acid Adsorption to Activated Carbon Air Cathodes Produces a Small Reduction in Catalytic Activity.

    PubMed

    Yang, Wulin; Watson, Valerie J; Logan, Bruce E

    2016-08-16

    Long-term operation of microbial fuel cells (MFCs) can result in substantial degradation of activated carbon (AC) air-cathode performance. To examine a possible role in fouling from organic matter in water, cathodes were exposed to high concentrations of humic acids (HA). Cathodes treated with 100 mg L(-1) HA exhibited no significant change in performance. Exposure to 1000 mg L(-1) HA decreased the maximum power density by 14% (from 1310 ± 30 mW m(-2) to 1130 ± 30 mW m(-2)). Pore blocking was the main mechanism as the total surface area of the AC decreased by 12%. Minimization of external mass transfer resistances using a rotating disk electrode exhibited only a 5% reduction in current, indicating about half the impact of HA adsorption was associated with external mass transfer resistance and the remainder was due to internal resistances. Rinsing the cathodes with deionized water did not restore cathode performance. These results demonstrated that HA could contribute to cathode fouling, but the extent of power reduction was relatively small in comparison to large mass of humics adsorbed. Other factors, such as biopolymer attachment, or salt precipitation, are therefore likely more important contributors to long-term fouling of MFC cathodes.

  11. Domestic wastewater treatment and power generation in continuous flow air-cathode stacked microbial fuel cell: Effect of series and parallel configuration.

    PubMed

    Estrada-Arriaga, Edson Baltazar; Hernández-Romano, Jesús; García-Sánchez, Liliana; Guillén Garcés, Rosa Angélica; Bahena-Bahena, Erick Obed; Guadarrama-Pérez, Oscar; Moeller Chavez, Gabriela Eleonora

    2018-05-15

    In this study, a continuous flow stack consisting of 40 individual air-cathode MFC units was used to determine the performance of stacked MFC during domestic wastewater treatment operated with unconnected individual MFC and in series and parallel configuration. The voltages obtained from individual MFC units were of 0.08-1.1 V at open circuit voltage, while in series connection, the maximum power and current density were 2500 mW/m 2 and 500 mA/m 2 (4.9 V), respectively. In parallel connection, the maximum power and current density was 5.8 mW/m 2 and 24 mA/m 2 , respectively. When the cells were not connected to each other MFC unit, the main bacterial species found in the anode biofilms were Bacillus and Lysinibacillus. After switching from unconnected to series and parallel connections, the most abundant species in the stacked MFC were Pseudomonas aeruginosa, followed by different Bacilli classes. This study demonstrated that when the stacked MFC was switched from unconnected to series and parallel connections, the pollutants removal, performance electricity and microbial community changed significantly. Voltages drops were observed in the stacked MFC, which was mainly limited by the cathodes. These voltages loss indicated high resistances within the stacked MFC, generating a parasitic cross current. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. FePO4 based single chamber air-cathode microbial fuel cell for online monitoring levofloxacin.

    PubMed

    Zeng, Libin; Li, Xinyong; Shi, Yueran; Qi, Yefei; Huang, Daqiong; Tadé, Moses; Wang, Shaobin; Liu, Shaomin

    2017-05-15

    A bio-electrochemical strategy was developed for constructing a simple and sensitive levofloxacin (LEV) sensor based on a single chamber microbial fuel cell (SC-MFC) using FePO 4 nanoparticles (NPs) as the cathode catalyst instead of traditional Pt/C. In this assembled sensor device, FePO 4 NPs dramatically promoted the electrooxidation of oxygen on the cathode, which helps to accelerate the voltage output from SC-MFC and can provide a powerful guarantee for LEV detection. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to fully characterize the FePO 4 NPs. Under the optimized COD condition (3mM), the LEV with a concentration range of 0.1-1000µg/L could be detected successfully, and exhibited the excellent linear interval in the concentration range of 0.1-100µg/L. During this range of concentrations of LEV, a temporary effect on the anode of exoelectrogenic bacterial in less than 10min could occur, and then came back to the normal. It exhibited a long-term stability, maintaining the stable electricity production for 14 months of continuous running. Besides, the detection mechanism was investigated by quantum chemical calculation using density functional theory (DFT). Copyright © 2016. Published by Elsevier B.V.

  13. Effect of gradual transition of substrate on performance of flat-panel air-cathode microbial fuel cells to treat domestic wastewater.

    PubMed

    Park, Younghyun; Park, Seonghwan; Nguyen, Van Khanh; Kim, Jung Rae; Kim, Hong Suck; Kim, Byung Goon; Yu, Jaecheul; Lee, Taeho

    2017-02-01

    In order to confirm the effects of the low conductivity and biodegradability of wastewater, flat-panel air-cathode microbial fuel cells (FA-MFCs) were operated by supplying substrates with different volume ratios of domestic wastewater mixed with an artificial medium: the artificial medium only, 25% wastewater, 50% wastewater, 75% wastewater, 100% of wastewater with 500mg-COD/L by adding acetate, and raw domestic wastewater (230mg-COD/L). With the increase of wastewater ratio, the maximum power density and organic removal efficiency decreased from 187 to 60W/m 3 and 51.5 to 37.4%, respectively, but the Coulombic efficiency was maintained in the range of 18.0-18.9%. The FA-MFCs could maintain their low internal resistances and overcome the decreasing conductivity. The acetate concentration was more important than the total organics for power production. This study suggests that the FA-MFC configuration has great applicability for practical applications when supplied by domestic wastewater with low conductivity and biodegradability. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Commercial materials as cathode for hydrogen production in microbial electrolysis cell.

    PubMed

    Farhangi, Sara; Ebrahimi, Sirous; Niasar, Mojtaba Shariati

    2014-10-01

    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.

  15. Porous metal-organic framework Cu3(BTC)2 as catalyst used in air-cathode for high performance of microbial fuel cell.

    PubMed

    Tian, Pei; Liu, Di; Li, Kexun; Yang, Tingting; Wang, Junjie; Liu, Yi; Zhang, Song

    2017-11-01

    Metal-organic framework Cu 3 (BTC) 2 , prepared by an easy hydrothermal method, was used as the oxygen-based catalyst in microbial fuel cell (MFC). The maximum power density of Cu 3 (BTC) 2 modified air-cathode MFC was 1772±15mWm -2 , almost 1.8 times higher than the control. BET results disclosed high specific surface area of 2159.7m 2 g -1 and abundant micropores structure. Regular octahedron and porous surface of Cu 3 (BTC) 2 were observed in SEM. XPS testified the existence of divalent copper in the extended 3D frameworks, which importantly acted as the Lewis-acid sites or redox centers in ORR. Additionally, the total resistance decreased by 42% from 17.60 to 10.24Ω compared with bare AC electrode. The rotating disk electrode test results showed a four-electron transfer pathway for Cu 3 (BTC) 2 , which was crucial for electrochemical catalytic activity. All the structural and electrochemical advantages make Cu 3 (BTC) 2 a promising catalyst for ORR in MFC. Copyright © 2017. Published by Elsevier Ltd.

  16. Cathodic microbial community adaptation to the removal of chlorinated herbicide in soil microbial fuel cells.

    PubMed

    Li, Yue; Li, Xiaojing; Sun, Yang; Zhao, Xiaodong; Li, Yongtao

    2018-04-05

    The microbial fuel cell (MFC) that uses a solid electrode as the inexhaustible electron acceptor is an innovative remediation technology that simultaneously generates bioelectricity. Chlorinated pollutants are better metabolized by reductive dechlorination in proximity to the cathode. Here, the removal efficiency of the herbicide metolachlor (ML) increased by 262 and 176% in soil MFCs that were spiked with 10 (C10) and 20 mg/kg (C20) of ML, respectively, relative to the non-electrode controls. The bioelectricity output of the C10 and C20 increased by over two- and eightfold, respectively, compared to that of the non-ML control, with maximum current densities of 49.6 ± 2.5 (C10) and 78.9 ± 0.6 mA/m 2 (C20). Based on correlations between ML concentrations and species abundances in the MFCs, it was inferred that Azohydromonas sp., Sphingomonas sp., and Pontibacter sp. play a major role in ML removal around the cathode, with peak removal efficiencies of 56 ± 1% (C10) and 58 ± 1% (C20). Moreover, Clostridium sp., Geobacter sp., Bacillus sp., Romboutsia sp., and Terrisporobacter sp. may be electricigens or closely related microbes due to the significant positive correlation between the bioelectricity generation levels and their abundances around the anode. This study suggests that a directional adaptation of the microbial community has taken place to increase both the removal of chlorinated herbicides around the cathode and the generation of bioelectricity around the anode in bioelectrochemical remediation systems.

  17. Vertically aligned carbon nanotubes as anode and air-cathode in single chamber microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Amade, R.; Moreno, H. A.; Hussain, S.; Vila-Costa, M.; Bertran, E.

    2016-10-01

    Electrode optimization in microbial fuel cells is a key issue to improve the power output and cell performance. Vertically aligned carbon nanotubes (VACNTs) grown on low cost stainless-steel mesh present an attractive approach to increase the cell performance while avoiding the use of expensive Pt-based materials. In comparison with non-aligned carbon nanotubes (NACNTs), VACNTs increase the oxygen reduction reaction taking place at the cathode by a factor of two. In addition, vertical alignment also increases the power density up to 2.5 times with respect to NACNTs. VACNTs grown at the anode can further improve the cell performance by increasing the electrode surface area and thus the electron transfer between bacteria and the electrode. The maximum power density obtained using VACNTs was 14 mW/m2 and 160 mV output voltage.

  18. Core-shell Au-Pd nanoparticles as cathode catalysts for microbial fuel cell applications

    PubMed Central

    Yang, Gaixiu; Chen, Dong; Lv, Pengmei; Kong, Xiaoying; Sun, Yongming; Wang, Zhongming; Yuan, Zhenhong; Liu, Hui; Yang, Jun

    2016-01-01

    Bimetallic nanoparticles with core-shell structures usually display enhanced catalytic properties due to the lattice strain created between the core and shell regions. In this study, we demonstrate the application of bimetallic Au-Pd nanoparticles with an Au core and a thin Pd shell as cathode catalysts in microbial fuel cells, which represent a promising technology for wastewater treatment, while directly generating electrical energy. In specific, in comparison with the hollow structured Pt nanoparticles, a benchmark for the electrocatalysis, the bimetallic core-shell Au-Pd nanoparticles are found to have superior activity and stability for oxygen reduction reaction in a neutral condition due to the strong electronic interaction and lattice strain effect between the Au core and the Pd shell domains. The maximum power density generated in a membraneless single-chamber microbial fuel cell running on wastewater with core-shell Au-Pd as cathode catalysts is ca. 16.0 W m−3 and remains stable over 150 days, clearly illustrating the potential of core-shell nanostructures in the applications of microbial fuel cells. PMID:27734945

  19. Long-term cathode performance and the microbial communities that develop in microbial fuel cells fed different fermentation endproducts.

    PubMed

    Kiely, Patrick D; Rader, Geoffrey; Regan, John M; Logan, Bruce E

    2011-01-01

    To better understand how cathode performance and substrates affected communities that evolved in these reactors over long periods of time, microbial fuel cells were operated for more than 1 year with individual endproducts of lignocellulose fermentation (acetic acid, formic acid, lactic acid, succinic acid, or ethanol). Large variations in reactor performance were primarily due to the specific substrates, with power densities ranging from 835 ± 21 to 62 ± 1mW/m(3). Cathodes performance degraded over time, as shown by an increase in power of up to 26% when the cathode biofilm was removed, and 118% using new cathodes. Communities that developed on the anodes included exoelectrogenic families, such as Rhodobacteraceae, Geobacteraceae, and Peptococcaceae, with the Deltaproteobacteria dominating most reactors. Pelobacter propionicus was the predominant member in reactors fed acetic acid, and it was abundant in several other MFCs. These results provide valuable insights into the effects of long-term MFC operation on reactor performance. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Nickel-based electrodeposits as potential cathode catalysts for hydrogen production by microbial electrolysis

    NASA Astrophysics Data System (ADS)

    Mitov, M.; Chorbadzhiyska, E.; Nalbandian, L.; Hubenova, Y.

    2017-07-01

    The development of cost-effective cathodes, operating at neutral pH and ambient temperatures, is a crucial challenge for the practical application of microbial electrolysis cell (MEC) technology. In this study, NiW and NiMo co-deposits produced by electroplating on Ni-foam are explored as cathodes in MEC. The fabricated electrodes exhibit higher corrosion stability and enhanced electrocatalytic activity towards hydrogen evolution reaction in neutral electrolyte compared to the bare Ni-foam. NiW/Ni-foam electrodes possess six times higher intrinsic catalytic activity, estimated from data obtained by linear voltammetry and chronoamperometry. The newly developed electrodes are applied as cathodes in single-chamber membrane-free MEC reactors, inoculated with wastewater and activated sludge from a municipal wastewater treatment plant. Cathodic hydrogen recovery of 79% and 89% by using NiW and NiMo cathodes, respectively, is achieved at applied voltage of 0.6 V. The obtained results reveal potential for practical application of used catalysts in MEC.

  1. Nano-structured manganese oxide as a cathodic catalyst for enhanced oxygen reduction in a microbial fuel cell fed with a synthetic wastewater.

    PubMed

    Liu, Xian-Wei; Sun, Xue-Fei; Huang, Yu-Xi; Sheng, Guo-Ping; Zhou, Kang; Zeng, Raymond J; Dong, Fang; Wang, Shu-Guang; Xu, An-Wu; Tong, Zhong-Hua; Yu, Han-Qing

    2010-10-01

    Microbial fuel cells (MFCs) provide new opportunities for the simultaneous wastewater treatment and electricity generation. Enhanced oxygen reduction capacity of cost-effective metal-based catalysts in an air cathode is essential for the scale-up and commercialization of MFCs in the field of wastewater treatment. We demonstrated that a nano-structured MnO(x) material, prepared by an electrochemically deposition method, could be an effective catalyst for oxygen reduction in an MFC to generate electricity with the maximum power density of 772.8 mW/m(3) and remove organics when the MFC was fed with an acetate-laden synthetic wastewater. The nano-structured MnO(x) with the controllable size and morphology could be readily obtained with the electrochemical deposition method. Both morphology and manganese oxidation state of the nano-scale catalyst were largely dependent on the electrochemical preparation process, and they governed its catalytic activity and the cathodic oxygen reduction performance of the MFC accordingly. Furthermore, cyclic voltammetry (CV) performed on each nano-structured material suggests that the MnO(x) nanorods had an electrochemical activity towards oxygen reduction reaction via a four-electron pathway in a neutral pH solution. This work provides useful information on the facile preparation of cost-effective cathodic catalysts in a controllable way for the single-chamber air-cathode MFC for wastewater treatment. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Three-dimensional graphene nanosheets as cathode catalysts in standard and supercapacitive microbial fuel cell

    NASA Astrophysics Data System (ADS)

    Santoro, Carlo; Kodali, Mounika; Kabir, Sadia; Soavi, Francesca; Serov, Alexey; Atanassov, Plamen

    2017-07-01

    Three-dimensional graphene nanosheets (3D-GNS) were used as cathode catalysts for microbial fuel cells (MFCs) operating in neutral conditions. 3D-GNS catalysts showed high performance towards oxygen electroreduction in neutral media with high current densities and low hydrogen peroxide generation compared to activated carbon (AC). 3D-GNS was incorporated into air-breathing cathodes based on AC with three different loadings (2, 6 and 10 mgcm-2). Performances in MFCs showed that 3D-GNS had the highest performances with power densities of 2.059 ± 0.003 Wm-2, 1.855 ± 0.007 Wm-2 and 1.503 ± 0.005 Wm-2 for loading of 10, 6 and 2 mgcm-2 respectively. Plain AC had the lowest performances (1.017 ± 0.009 Wm-2). The different cathodes were also investigated in supercapacitive MFCs (SC-MFCs). The addition of 3D-GNS decreased the ohmic losses by 14-25%. The decrease in ohmic losses allowed the SC-MFC with 3D-GNS (loading 10 mgcm-2) to have the maximum power (Pmax) of 5.746 ± 0.186 Wm-2. At 5 mA, the SC-MFC featured an "apparent" capacitive response that increased from 0.027 ± 0.007 F with AC to 0.213 ± 0.026 F with 3D-GNS (loading 2 mgcm-2) and further to 1.817 ± 0.040 F with 3D-GNS (loading 10 mgcm-2).

  3. Nitrogen-doped carbonaceous catalysts for gas-diffusion cathodes for alkaline aluminum-air batteries

    NASA Astrophysics Data System (ADS)

    Davydova, E. S.; Atamanyuk, I. N.; Ilyukhin, A. S.; Shkolnikov, E. I.; Zhuk, A. Z.

    2016-02-01

    Cobalt tetramethoxyphenyl porphyrin and polyacrylonitrile - based catalysts for oxygen reduction reaction were synthesized and characterized by means of SEM, TEM, XPS, BET, limited evaporation method, rotating disc and rotating ring-disc electrode methods. Half-cell and Al-air cell tests were carried out to determine the characteristics of gas-diffusion cathodes. Effect of active layer thickness and its composition on the characteristics of the gas-diffusion cathodes was investigated. Power density of 300 mW cm-2 was achieved for alkaline Al-air cell with an air-breathing polyacrylonitrile-based cathode.

  4. Understanding the degradation of Congo red and bacterial diversity in an air-cathode microbial fuel cell being evaluated for simultaneous azo dye removal from wastewater and bioelectricity generation.

    PubMed

    Sun, Jian; Li, Youming; Hu, Yongyou; Hou, Bin; Zhang, Yaping; Li, Sizhe

    2013-04-01

    We investigated the mechanism of Congo red degradation and bacterial diversity in a single-chambered microbial fuel cell (MFC) incorporating a microfiltration membrane and air-cathode. The MFC was operated continuously for more than 4 months using a mixture of Congo red and glucose as fuel. We demonstrated that the Congo red azo bonds were reduced at the anode to form aromatic amines. This is consistent with the known mechanism of anaerobic biodegradation of azo dyes. The MFC developed a less dense biofilm at the anode in the presence of Congo red compared to its absence indicating that Congo red degradation negatively affected biofilm formation. Denaturing gradient gel electrophoresis and direct 16S ribosomal DNA gene nucleotide sequencing revealed that the microbial communities differed depending on whether Congo red was present in the MFC. Geobacter-like species known to generate electricity were detected in the presence or absence of Congo red. In contrast, Azospirillum, Methylobacterium, Rhodobacter, Desulfovibrio, Trichococcus, and Bacteroides species were only detected in its presence. These species were most likely responsible for degrading Congo red.

  5. Outward electron transfer by Saccharomyces cerevisiae monitored with a bi-cathodic microbial fuel cell-type activity sensor.

    PubMed

    Ducommun, Raphaël; Favre, Marie-France; Carrard, Delphine; Fischer, Fabian

    2010-03-01

    A Janus head-like bi-cathodic microbial fuel cell was constructed to monitor the electron transfer from Saccharomyces cerevisiae to a woven carbon anode. The experiments were conducted during an ethanol cultivation of 170 g/l glucose in the presence and absence of yeast-peptone medium. First, using a basic fuel-cell type activity sensor, it was shown that yeast-peptone medium contains electroactive compounds. For this purpose, 1% solutions of soy peptone and yeast extract were subjected to oxidative conditions, using a microbial fuel cell set-up corresponding to a typical galvanic cell, consisting of culture medium in the anodic half-cell and 0.5 M K(3)Fe(CN)(6) in the cathodic half-cell. Second, using a bi-cathodic microbial fuel cell, it was shown that electrons were transferred from yeast cells to the carbon anode. The participation of electroactive compounds in the electron transport was separated as background current. This result was verified by applying medium-free conditions, where only glucose was fed, confirming that electrons are transferred from yeast cells to the woven carbon anode. Knowledge about the electron transfer through the cell membrane is of importance in amperometric online monitoring of yeast fermentations and for electricity production with microbial fuel cells. Copyright (c) 2009 John Wiley & Sons, Ltd.

  6. Electricity generation and brewery wastewater treatment from sequential anode-cathode microbial fuel cell.

    PubMed

    Wen, Qing; Wu, Ying; Zhao, Li-xin; Sun, Qian; Kong, Fan-ying

    2010-02-01

    A sequential anode-cathode double-chamber microbial fuel cell (MFC), in which the effluent of anode chamber was used as a continuous feed for an aerated cathode chamber, was constructed in this experiment to investigate the performance of brewery wastewater treatment in conjugation with electricity generation. Carbon fiber was used as anode and plain carbon felt with biofilm as cathode. When hydraulic retention time (HRT) was 14.7 h, a relatively high chemical oxygen demand (COD) removal efficiency of 91.7%-95.7% was achieved under long-term stable operation. The MFC displayed an open circuit voltage of 0.434 V and a maximum power density of 830 mW/m(3) at an external resistance of 300 Omega. To estimate the electrochemical performance of the MFC, electrochemical measurements were carried out and showed that polarization resistance of anode was the major limiting factor in the MFC. Since a high COD removal efficiency was achieved, we conclude that the sequential anode-cathode MFC constructed with bio-cathode in this experiment could provide a new approach for brewery wastewater treatment.

  7. Electricity generation and brewery wastewater treatment from sequential anode-cathode microbial fuel cell*

    PubMed Central

    Wen, Qing; Wu, Ying; Zhao, Li-xin; Sun, Qian; Kong, Fan-ying

    2010-01-01

    A sequential anode-cathode double-chamber microbial fuel cell (MFC), in which the effluent of anode chamber was used as a continuous feed for an aerated cathode chamber, was constructed in this experiment to investigate the performance of brewery wastewater treatment in conjugation with electricity generation. Carbon fiber was used as anode and plain carbon felt with biofilm as cathode. When hydraulic retention time (HRT) was 14.7 h, a relatively high chemical oxygen demand (COD) removal efficiency of 91.7%–95.7% was achieved under long-term stable operation. The MFC displayed an open circuit voltage of 0.434 V and a maximum power density of 830 mW/m3 at an external resistance of 300 Ω. To estimate the electrochemical performance of the MFC, electrochemical measurements were carried out and showed that polarization resistance of anode was the major limiting factor in the MFC. Since a high COD removal efficiency was achieved, we conclude that the sequential anode-cathode MFC constructed with bio-cathode in this experiment could provide a new approach for brewery wastewater treatment. PMID:20104642

  8. Graphitic biochar as a cathode electrocatalyst support for microbial fuel cells.

    PubMed

    Huggins, Tyler M; Pietron, Jeremy J; Wang, Heming; Ren, Zhiyong Jason; Biffinger, Justin C

    2015-11-01

    Graphitic biochar (BC) was generated using high temperature gasification and alkaline post-treatment (BCw) of wood-based biomass. The BCw was evaluated as a manganese oxide electrocatalytic support (MnO/BCw) and microbial fuel cell (MFC) air cathode. Nano-structured MnO2 crystals were successfully immobilized on biomass-based graphitic sheets and characterized using physical, chemical, and electrochemical analyses. Cyclic voltammetry of MnO/BCw/Nafion inks showed electrochemical features typical of β-MnO2 with a current density of 0.9 mA cm(-2). BC showed satisfactory maximum power densities of 146.7 mW m(-2) (BCw) and 187.8 W m(-2) (MnO/BCw), compared with Vulcan Carbon (VC) (156.8 mW m(-2)) and manganese oxide VC composites (MnO/VC) (606.1 mW m(-2)). These materials were also tested as oxygen reduction reaction (ORR) catalysts for single chamber MFCs inoculated with anaerobic sludge. Our results demonstrate that BC can serve as an effective, low cost, and scalable material for MFC application. Published by Elsevier Ltd.

  9. Lithium-Air Battery: High Performance Cathodes for Lithium-Air Batteries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    None

    2010-08-01

    BEEST Project: Researchers at Missouri S&T are developing an affordable lithium-air (Li-Air) battery that could enable an EV to travel up to 350 miles on a single charge. Today’s EVs run on Li-Ion batteries, which are expensive and suffer from low energy density compared with gasoline. This new Li-Air battery could perform as well as gasoline and store 3 times more energy than current Li-Ion batteries. A Li-Air battery uses an air cathode to breathe oxygen into the battery from the surrounding air, like a human lung. The oxygen and lithium react in the battery to produce electricity. Current Li-Airmore » batteries are limited by the rate at which they can draw oxygen from the air. The team is designing a battery using hierarchical electrode structures to enhance air breathing and effective catalysts to accelerate electricity production.« less

  10. A study of microbial communities on terracotta separator and on biocathode of air breathing microbial fuel cells.

    PubMed

    Rago, Laura; Zecchin, Sarah; Marzorati, Stefania; Goglio, Andrea; Cavalca, Lucia; Cristiani, Pierangela; Schievano, Andrea

    2018-04-01

    Recently, terracotta has attracted interest as low-cost and biocompatible material to build separators in microbial fuel cells (MFCs). However, the influence of a non-conductive material like terracotta on electroactive microbiological communities remains substantially unexplored. This study aims at describing the microbial pools developed from two different seed inocula (bovine and swine sewage) in terracotta-based air-breathing MFC. A statistical approach on microbiological data confirmed different community enrichment in the MFCs, depending mainly on the inoculum. Terracotta separators impeded the growth of electroactive communities in contact with cathodes (biocathodes), while a thick biofilm was observed on the surface (anolyte-side) of the terracotta separator. Terracotta-free MFCs, set as control experiments, showed a well-developed biocathode, Biocathode-MFCs resulted in 4 to 6-fold higher power densities. All biofilms were analyzed by high-throughput Illumina sequencing applied to 16S rRNA gene. The results showed more abundant (3- to 5-fold) electroactive genera (mainly Geobacter, Pseudomonas, Desulfuromonas and Clostridia MBA03) in terracotta-free biocathodes. Nevertheless, terracotta separators induced only slight changes in anodic microbial communities. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Potential of porous Co3O4 nanorods as cathode catalyst for oxygen reduction reaction in microbial fuel cells.

    PubMed

    Kumar, Ravinder; Singh, Lakhveer; Zularisam, A W; Hai, Faisal I

    2016-11-01

    This study aims to investigate the potential of porous Co3O4 nanorods as the cathode catalyst for oxygen reduction reaction (ORR) in aqueous air cathode microbial fuel cells (MFCs). The porous Co3O4 nanorods were synthesized by a facile and cost-effective hydrothermal method. Three different concentrations (0.5mg/cm(2), 1mg/cm(2), and 2mg/cm(2)) of Co3O4 nanorods coated on graphite electrodes were used to test its performance in MFCs. The results showed that the addition of porous Co3O4 nanorods enhanced the electrocatalytic activity and ORR kinetics significantly and the overall resistance of the system was greatly reduced. Moreover, the MFC with a higher concentration of the catalyst achieved a maximum power density of 503±16mW/m(2), which was approximately five times higher than the bare graphite electrode. The improved catalytic activity of the cathodes could be due to the porous properties of Co3O4 nanorods that provided the higher number of active sites for oxygen. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Influences of dissolved oxygen concentration on biocathodic microbial communities in microbial fuel cells.

    PubMed

    Rago, Laura; Cristiani, Pierangela; Villa, Federica; Zecchin, Sarah; Colombo, Alessandra; Cavalca, Lucia; Schievano, Andrea

    2017-08-01

    Dissolved oxygen (DO) at cathodic interface is a critical factor influencing microbial fuel cells (MFC) performance. In this work, three MFCs were operated with cathode under different DO conditions: i) air-breathing (A-MFC); ii) water-submerged (W-MFC) and iii) assisted by photosynthetic microorganisms (P-MFC). A plateau of maximum current was reached at 1.06±0.03mA, 1.48±0.06mA and 1.66±0.04mA, increasing respectively for W-MFC, P-MFC and A-MFC. Electrochemical and microbiological tools (Illumina sequencing, confocal microscopy and biofilm cryosectioning) were used to explore anodic and cathodic biofilm in each MFC type. In all cases, biocathodes improved oxygen reduction reaction (ORR) as compared to abiotic condition and A-MFC was the best performing system. Photosynthetic cultures in the cathodic chamber supplied high DO level, up to 16mg O2 L -1 , which sustained aerobic microbial community in P-MFC biocathode. Halomonas, Pseudomonas and other microaerophilic genera reached >50% of the total OTUs. The presence of sulfur reducing bacteria (Desulfuromonas) and purple non-sulfur bacteria in A-MFC biocathode suggested that the recirculation of sulfur compounds could shuttle electrons to sustain the reduction of oxygen as final electron acceptor. The low DO concentration limited the cathode in W-MFC. A model of two different possible microbial mechanisms is proposed which can drive predominantly cathodic ORR. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Meta-proteomic analysis of protein expression distinctive to electricity-generating biofilm communities in air-cathode microbial fuel cells.

    PubMed

    Chignell, Jeremy F; De Long, Susan K; Reardon, Kenneth F

    2018-01-01

    denitrification and competitive inhibition. The results demonstrate that it is possible for an MFC microbial community to generate robust current densities while exhibiting high taxonomic diversity. Moreover, these data provide evidence to suggest that startup growth of air-cathode MFCs under conditions that promote the establishment of aerobic-anaerobic syntrophy may decrease startup times. This study represents the first investigation into protein expression of a complex BES anode biofilm community as a whole. The findings contribute to understanding of the molecular mechanisms at work during BES startup and suggest options for improvement of BES generation of bioelectricity from renewable biomass.

  14. Ultrahigh-Capacity Lithium-Oxygen Batteries Enabled by Dry-Pressed Holey Graphene Air Cathodes.

    PubMed

    Lin, Yi; Moitoso, Brandon; Martinez-Martinez, Chalynette; Walsh, Evan D; Lacey, Steven D; Kim, Jae-Woo; Dai, Liming; Hu, Liangbing; Connell, John W

    2017-05-10

    Lithium-oxygen (Li-O 2 ) batteries have the highest theoretical energy density of all the Li-based energy storage systems, but many challenges prevent them from practical use. A major obstacle is the sluggish performance of the air cathode, where both oxygen reduction (discharge) and oxygen evolution (charge) reactions occur. Recently, there have been significant advances in the development of graphene-based air cathode materials with a large surface area and catalytically active for both oxygen reduction and evolution reactions, especially with additional catalysts or dopants. However, most studies reported so far have examined air cathodes with a limited areal mass loading rarely exceeding 1 mg/cm 2 . Despite the high gravimetric capacity values achieved, the actual (areal) capacities of those batteries were far from sufficient for practical applications. Here, we present the fabrication, performance, and mechanistic investigations of high-mass-loading (up to 10 mg/cm 2 ) graphene-based air electrodes for high-performance Li-O 2 batteries. Such air electrodes could be easily prepared within minutes under solvent-free and binder-free conditions by compression-molding holey graphene materials because of their unique dry compressibility associated with in-plane holes on the graphene sheet. Li-O 2 batteries with high air cathode mass loadings thus prepared exhibited excellent gravimetric capacity as well as ultrahigh areal capacity (as high as ∼40 mAh/cm 2 ). The batteries were also cycled at a high curtailing areal capacity (2 mAh/cm 2 ) and showed a better cycling stability for ultrathick cathodes than their thinner counterparts. Detailed post-mortem analyses of the electrodes clearly revealed the battery failure mechanisms under both primary and secondary modes, arising from the oxygen diffusion blockage and the catalytic site deactivation, respectively. These results strongly suggest that the dry-pressed holey graphene electrodes are a highly viable

  15. An air-breathing enzymatic cathode with extended lifetime by continuous laccase supply.

    PubMed

    Kipf, Elena; Sané, Sabine; Morse, Daniel; Messinger, Thorsten; Zengerle, Roland; Kerzenmacher, Sven

    2018-04-22

    We present a novel concept of an air-breathing enzymatic biofuel cell cathode combined with continuous supply of unpurified laccase-containing supernatant of the white-rot fungus Trametes versicolor for extended lifetime. The air-breathing cathode design obviates the need for energy-intensive active aeration. In a corresponding long-term experiment at a constant current density of 50 µA cm -2 , we demonstrated an increased lifetime of 33 days (cathode potential above 0.430 V vs. SCE), independent of enzyme degradation. The obtained data suggest that theoretically a longer lifetime is feasible. However, further engineering efforts are required to prevent clogging and fouling of the supply tubes. These results represent an important step towards the realization of enzymatic biofuel cell cathodes with extended lifetime and enhanced performance. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Carbonate-mediated Fe(II) oxidation in the air-cathode fuel cell: a kinetic model in terms of Fe(II) speciation.

    PubMed

    Song, Wei; Zhai, Lin-Feng; Cui, Yu-Zhi; Sun, Min; Jiang, Yuan

    2013-06-06

    Due to the high redox activity of Fe(II) and its abundance in natural waters, the electro-oxidation of Fe(II) can be found in many air-cathode fuel cell systems, such as acid mine drainage fuel cells and sediment microbial fuel cells. To deeply understand these iron-related systems, it is essential to elucidate the kinetics and mechanisms involved in the electro-oxidation of Fe(II). This work aims to develop a kinetic model that adequately describes the electro-oxidation process of Fe(II) in air-cathode fuel cells. The speciation of Fe(II) is incorporated into the model, and contributions of individual Fe(II) species to the overall Fe(II) oxidation rate are quantitatively evaluated. The results show that the kinetic model can accurately predict the electro-oxidation rate of Fe(II) in air-cathode fuel cells. FeCO3, Fe(OH)2, and Fe(CO3)2(2-) are the most important species determining the electro-oxidation kinetics of Fe(II). The Fe(II) oxidation rate is primarily controlled by the oxidation of FeCO3 species at low pH, whereas at high pH Fe(OH)2 and Fe(CO3)2(2-) are the dominant species. Solution pH, carbonate concentration, and solution salinity are able to influence the electro-oxidation kinetics of Fe(II) through changing both distribution and kinetic activity of Fe(II) species.

  17. Spray-on polyvinyl alcohol separators and impact on power production in air-cathode microbial fuel cells with different solution conductivities.

    PubMed

    Hoskins, Daniel L; Zhang, Xiaoyuan; Hickner, Michael A; Logan, Bruce E

    2014-11-01

    Separators are used to protect cathodes from biofouling and to avoid electrode short-circuiting, but they can adversely affect microbial fuel cell (MFC) performance. A spray method was used to apply a polyvinyl alcohol (PVA) separator to the cathode. Power densities were unaffected by the PVA separator (339±29mW/m(2)), compared to a control lacking a separator in a low conductivity solution (1mS/cm) similar to wastewater. Power was reduced with separators in solutions typical of laboratory tests (7-13mS/cm), compared to separatorless controls. The PVA separator produced more power in a separator assembly (SEA) configuration (444±8mW/m(2)) in the 1mS/cm solution, but power was reduced if a PVA or wipe separator was used in higher conductivity solutions with either Pt or activated carbon catalysts. Spray and cast PVA separators performed similarly, but the spray method is preferred as it was easier to apply and use. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Three-dimensional graphene nanosheets as cathode catalysts in standard and supercapacitive microbial fuel cell.

    PubMed

    Santoro, Carlo; Kodali, Mounika; Kabir, Sadia; Soavi, Francesca; Serov, Alexey; Atanassov, Plamen

    2017-07-15

    Three-dimensional graphene nanosheets (3D-GNS) were used as cathode catalysts for microbial fuel cells (MFCs) operating in neutral conditions. 3D-GNS catalysts showed high performance towards oxygen electroreduction in neutral media with high current densities and low hydrogen peroxide generation compared to activated carbon (AC). 3D-GNS was incorporated into air-breathing cathodes based on AC with three different loadings (2, 6 and 10 mgcm -2 ). Performances in MFCs showed that 3D-GNS had the highest performances with power densities of 2.059 ± 0.003 Wm -2 , 1.855 ± 0.007 Wm -2 and 1.503 ± 0.005 Wm -2 for loading of 10, 6 and 2 mgcm -2 respectively. Plain AC had the lowest performances (1.017 ± 0.009 Wm -2 ). The different cathodes were also investigated in supercapacitive MFCs (SC-MFCs). The addition of 3D-GNS decreased the ohmic losses by 14-25%. The decrease in ohmic losses allowed the SC-MFC with 3D-GNS (loading 10 mgcm -2 ) to have the maximum power (P max ) of 5.746 ± 0.186 Wm -2 . At 5 mA, the SC-MFC featured an "apparent" capacitive response that increased from 0.027 ± 0.007 F with AC to 0.213 ± 0.026 F with 3D-GNS (loading 2 mgcm -2 ) and further to 1.817 ± 0.040 F with 3D-GNS (loading 10 mgcm -2 ).

  19. Explore various co-substrates for simultaneous electricity generation and Congo red degradation in air-cathode single-chamber microbial fuel cell.

    PubMed

    Cao, Yunqing; Hu, Yongyou; Sun, Jian; Hou, Bin

    2010-08-01

    Microbial fuel cell (MFC) holds a great promise to harvest electricity directly from a wide range of ready degradable organic matters and enhance degradation of some recalcitrant contaminants. Glucose, acetate sodium and ethanol were separately examined as co-substrates for simultaneous bioelectricity generation and Congo red degradation in a proton exchange membrane (PEM) air-cathode single-chamber MFC. The batch test results showed that more than 98% decolorization at the dye concentration of 300 mg/L were achieved within 36 h for all tested co-substrates during electricity generation. The decolorization rate was different with the co-substrates used. The fastest decolorization rate was achieved with glucose followed by ethanol and sodium acetate. Accumulated intermediates were observed during Congo red degradation which was demonstrated by UV-Visible spectra and high performance liquid chromatography (HPLC). Electricity generation was sustained and not significantly affected by the Congo red degradation. Glucose, acetate sodium and ethanol produced maximum power densities of 103 mW/m(2), 85.9 mW/m(2) and 63.2 mW/m(2), respectively, and the maximum voltage output decreased by only 7% to 15%. Our results demonstrated the feasibility of using various co-substrates for simultaneous decolorization of Congo red and bioelectricity generation in the MFC and showed that glucose was the preferred co-substrate. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  20. Cobalt porphyrin-based material as methanol tolerant cathode in single chamber microbial fuel cells (SCMFCs)

    NASA Astrophysics Data System (ADS)

    Liu, Bingchuan; Brückner, Cristian; Lei, Yu; Cheng, Yue; Santoro, Carlo; Li, Baikun

    2014-07-01

    This study focused on the development of novel cathode material based on the pyrolysis of [meso-tetrakis(2-thienyl)porphyrinato]Co(II) (CoTTP) for use in single chamber microbial fuel cells (SCMFCs) to treat wastewater containing methanol. The cathodes produced at two loadings (0.5 and 1.0 mg cm-2) were examined in batch mode SCMFCs treating methanol of different concentrations (ranging from 0.005 to 0.04 M) over a 900 h operational period. Methanol was completely removed in SCMFCs, and the cycle duration was prolonged at high methanol concentrations, indicating methanol was used as fuel in SCMFCs. Methanol had more poisoning effects to the traditional platinum (Pt) cathodes than to the CoTTP cathodes. Specifically, power generations from SCMFCs with Pt cathodes gradually decreased over time, while the ones with CoTTP cathodes remained stable, even at the highest methanol concentration (0.04 M). Cathode linear sweep voltammetry (LSVs) indicated that the electrocatalytic activity of the Pt cathode was suppressed by methanol. Higher CoTTP loadings had similar open circuit potential (OCP) but higher electrocatalytic activity than lower loadings. This study demonstrated that methanol can be co-digested with wastewater and converted to power in MFCs, and a novel cathode CoTTP catalyst exhibits higher tolerance towards methanol compared with traditional Pt catalyst.

  1. Simultaneous Congo red decolorization and electricity generation in air-cathode single-chamber microbial fuel cell with different microfiltration, ultrafiltration and proton exchange membranes.

    PubMed

    Hou, Bin; Sun, Jian; Hu, Yong-you

    2011-03-01

    Different microfiltration membrane (MFM), proton exchange membrane (PEM) and ultrafiltration membranes (UFMs) with different molecular cutoff weights of 1K (UFM-1K), 5K (UFM-5K) and 10K (UFM-10K) were incorporated into air-cathode single-chamber microbial fuel cells (MFCs) which were explored for simultaneous azo dye decolorization and electricity generation to investigate the effect of membrane on the performance of the MFC. Batch test results showed that the MFC with an UFM-1K produced the highest power density of 324 mW/m(2) coupled with an enhanced coulombic efficiency compared to MFM. The MFC with UMF-10K achieved the fastest decolorization rate (4.77 mg/L h), followed by MFM (3.61 mg/L h), UFM-5K (2.38 mg/L h), UFM-1K (2.02 mg/Lh) and PEM (1.72 mg/Lh). These results demonstrated the possibility of using various membranes in the system described here, and showed that UFM-1K was the best one based on the consideration of both cost and performance. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Response of microbial community structure to pre-acclimation strategies in microbial fuel cells for domestic wastewater treatment.

    PubMed

    Park, Younghyun; Cho, Hyunwoo; Yu, Jaechul; Min, Booki; Kim, Hong Suck; Kim, Byung Goon; Lee, Taeho

    2017-06-01

    Microbial community structures and performance of air-cathode microbial fuel cells (MFCs) inoculated with activated sludge from domestic wastewater were investigated to evaluate the effects of three substrate pre-acclimation strategies: 1, serial pre-acclimation with acetate and glucose before supplying domestic wastewater; 2, one step pre-acclimation with acetate before supplying domestic wastewater; and 3, direct supply of domestic wastewater without any pre-acclimation. Strategy 1 showed much higher current generation (1.4mA) and Coulombic efficiency (33.5%) than strategies 2 (0.7mA and 9.4%) and 3 (0.9mA and 10.3%). Pyrosequencing showed that microbial communities were significantly affected by pre-acclimation strategy. Although Proteobacteria was the dominant phylum with all strategies, Actinobacteria was abundant when MFCs were pre-acclimated with glucose after acetate. Not only anode-respiring bacteria (ARB) in the genus Geobacter but also non-ARB belonging to the family Anaerolinaceae seemed to play important roles in air-cathode MFCs to produce electricity from domestic wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Metal-air batteries: from oxygen reduction electrochemistry to cathode catalysts.

    PubMed

    Cheng, Fangyi; Chen, Jun

    2012-03-21

    Because of the remarkably high theoretical energy output, metal-air batteries represent one class of promising power sources for applications in next-generation electronics, electrified transportation and energy storage of smart grids. The most prominent feature of a metal-air battery is the combination of a metal anode with high energy density and an air electrode with open structure to draw cathode active materials (i.e., oxygen) from air. In this critical review, we present the fundamentals and recent advances related to the fields of metal-air batteries, with a focus on the electrochemistry and materials chemistry of air electrodes. The battery electrochemistry and catalytic mechanism of oxygen reduction reactions are discussed on the basis of aqueous and organic electrolytes. Four groups of extensively studied catalysts for the cathode oxygen reduction/evolution are selectively surveyed from materials chemistry to electrode properties and battery application: Pt and Pt-based alloys (e.g., PtAu nanoparticles), carbonaceous materials (e.g., graphene nanosheets), transition-metal oxides (e.g., Mn-based spinels and perovskites), and inorganic-organic composites (e.g., metal macrocycle derivatives). The design and optimization of air-electrode structure are also outlined. Furthermore, remarks on the challenges and perspectives of research directions are proposed for further development of metal-air batteries (219 references).

  4. [Microbial air purity in hospitals. Operating theatres with air conditioning system].

    PubMed

    Krogulski, Adam; Szczotko, Maciej

    2010-01-01

    The aim of this study was to show the influence of air conditioning control for microbial contamination of air inside the operating theatres equipped with correctly working air-conditioning system. This work was based on the results of bacteria and fungi concentration in hospital air obtained since 2001. Assays of microbial air purity conducted on atmospheric air in parallel with indoor air demonstrated that air filters applied in air-conditioning systems worked correctly in every case. To show the problem of fluctuation of bacteria concentration more precisely, every sequences of single results from successive measure series were examined independently.

  5. Nickel oxide and carbon nanotube composite (NiO/CNT) as a novel cathode non-precious metal catalyst in microbial fuel cells.

    PubMed

    Huang, Jianjian; Zhu, Nengwu; Yang, Tingting; Zhang, Taiping; Wu, Pingxiao; Dang, Zhi

    2015-10-15

    Comparing with the precious metal catalysts, non-precious metal catalysts were preferred to use in microbial fuel cells (MFCs) due to the low cost and high oxygen reduction reaction (ORR) efficiency. In this study, the transmission electron microscope and X-ray diffraction as well as Raman investigation revealed that the prepared nanoscale NiO was attached on the surface of CNT. Cyclic voltammogram and rotating ring-disk electrode tests showed that the NiO/CNT composite catalyst had an apparent oxygen reduction peak and 3.5 electron transfer pathway was acquired under oxygen atmosphere. The catalyst performance was highly dependent on the percentage of NiO in the CNT nanocomposites. When 77% NiO/CNT nano-sized composite was applied as cathode catalyst in membrane free single-chamber air cathode MFC, a maximum power density of 670 mW/m(2) and 0.772 V of OCV was obtained. Moreover, the MFC with pure NiO (control) could not achieve more than 0.1 V. All findings suggested that NiO/CNT could be a potential cathode catalyst for ORR in MFCs. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. In-situ Electrodeposition of Highly Active Silver Catalyst on Carbon Fiber Papers as Binder Free Cathodes for Aluminum-air Battery.

    PubMed

    Hong, Qingshui; Lu, Huimin

    2017-06-13

    Carbon fiber papers supported Ag catalysts (Ag/CFP) with different coverage of electro-active site are prepared by electrochemical deposition and used as binder free cathodes in primary aluminum-air (Al-air) battery. Scanning Electron Microscopy and X-ray Diffraction studies are carried out to characterize the as-prepared Ag/CFP air cathodes. Oxygen reduction reaction (ORR) activities on these air cathodes in alkaline solutions are systematic studied. A newly designed aluminum-air cell is used to further determine the cathodes performance under real operation condition and during the test, the Ag/CFP electrodes show outstanding catalytic activity for ORR in concentrated alkaline electrolyte, and no obvious activity degradation is observed after long-time discharge. The electrochemical test results display the dependence of coverage of the electro-active Ag on the catalytic performance of the air cathodes. The resulting primary Al-air battery made from the best-performing cathode shows an impressive discharge peak power density, outperforming that of using commercial nano-manganese catalyst air electrodes.

  7. Co3O4 nanoparticles decorated carbon nanofiber mat as binder-free air-cathode for high performance rechargeable zinc-air batteries

    NASA Astrophysics Data System (ADS)

    Li, Bing; Ge, Xiaoming; Goh, F. W. Thomas; Hor, T. S. Andy; Geng, Dongsheng; Du, Guojun; Liu, Zhaolin; Zhang, Jie; Liu, Xiaogang; Zong, Yun

    2015-01-01

    An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization and a post annealing process in air at a moderate temperature. Electrochemical studies suggest that the nanohybrid material effectively catalyzes oxygen reduction reaction via an ideal 4-electron transfer process and outperforms Pt/C in catalyzing oxygen evolution reactions. Accordingly, the prototype ZnABs exhibit a low discharge-charge voltage gap (e.g. 0.7 V, discharge-charge at 2 mA cm-2) with higher stability and longer cycle life compared to their counterparts constructed using Pt/C in air-cathode. Importantly, the hybrid nanofiber mat readily serves as an integrated air-cathode without the need of any further modification. Benefitting from its efficient catalytic activities and structural advantages, particularly the 3D architecture of highly conductive CNFs and the high loading density of strongly attached Co3O4 NPs on their surfaces, the resultant ZnABs show significantly improved performance with respect to the rate capability, cycling stability and current density, promising good potential in practical applications.An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization

  8. Binder materials for the cathodes applied to self-stratifying membraneless microbial fuel cell.

    PubMed

    Walter, Xavier Alexis; Greenman, John; Ieropoulos, Ioannis

    2018-04-19

    The recently developed self-stratifying membraneless microbial fuel cell (SSM-MFC) has been shown as a promising concept for urine treatment. The first prototypes employed cathodes made of activated carbon (AC) and polytetrafluoroethylene (PTFE) mixture. Here, we explored the possibility to substitute PTFE with either polyvinyl-alcohol (PVA) or PlastiDip (CPD; i.e. synthetic rubber) as binder for AC-based cathode in SSM-MFC. Sintered activated carbon (SAC) was also tested due to its ease of manufacturing and the fact that no stainless steel collector is needed. Results indicate that the SSM-MFC having PTFE cathodes were the most powerful measuring 1617 μW (11 W·m -3 or 101 mW·m -2 ). SSM-MFC with PVA and CPD as binders were producing on average the same level of power (1226 ± 90 μW), which was 24% less than the SSM-MFC having PTFE-based cathodes. When balancing the power by the cost and environmental impact, results clearly show that PVA was the best alternative. Power wise, the SAC cathodes were shown being the less performing (≈1070 μW). Nonetheless, the lower power of SAC was balanced by its inexpensiveness. Overall results indicate that (i) PTFE is yet the best binder to employ, and (ii) SAC and PVA-based cathodes are promising alternatives that would benefit from further improvements. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  9. Electricity generation from real industrial wastewater using a single-chamber air cathode microbial fuel cell with an activated carbon anode.

    PubMed

    Mohamed, Hend Omar; Obaid, M; Sayed, Enas Taha; Liu, Yang; Lee, Jinpyo; Park, Mira; Barakat, Nasser A M; Kim, Hak Yong

    2017-08-01

    This study introduces activated carbon (AC) as an effective anode for microbial fuel cells (MFCs) using real industrial wastewater without treatment or addition of external microorganism mediators. Inexpensive activated carbon is introduced as a proper electrode alternative to carbon cloth and carbon paper materials, which are considered too expensive for the large-scale application of MFCs. AC has a porous interconnected structure with a high bio-available surface area. The large surface area, in addition to the high macro porosity, facilitates the high performance by reducing electron transfer resistance. Extensive characterization, including surface morphology, material chemistry, surface area, mechanical strength and biofilm adhesion, was conducted to confirm the effectiveness of the AC material as an anode in MFCs. The electrochemical performance of AC was also compared to other anodes, i.e., Teflon-treated carbon cloth (CCT), Teflon-treated carbon paper (CPT), untreated carbon cloth (CC) and untreated carbon paper (CP). Initial tests of a single air-cathode MFC display a current density of 1792 mAm -2 , which is approximately four times greater than the maximum value of the other anode materials. COD analyses and Coulombic efficiency (CE) measurements for AC-MFC show the greatest removal of organic compounds and the highest CE efficiency (60 and 71%, respectively). Overall, this study shows a new economical technique for power generation from real industrial wastewater with no treatment and using inexpensive electrode materials.

  10. Oxygen-reducing biocathodes operating with passive oxygen transfer in microbial fuel cells.

    PubMed

    Xia, Xue; Tokash, Justin C; Zhang, Fang; Liang, Peng; Huang, Xia; Logan, Bruce E

    2013-02-19

    Oxygen-reducing biocathodes previously developed for microbial fuel cells (MFCs) have required energy-intensive aeration of the catholyte. To avoid the need for aeration, the ability of biocathodes to function with passive oxygen transfer was examined here using air cathode MFCs. Two-chamber, air cathode MFCs with biocathodes produced a maximum power density of 554 ± 0 mW/m(2), which was comparable to that obtained with a Pt cathode (576 ± 16 mW/m(2)), and 38 times higher than that produced without a catalyst (14 ± 3 mW/m(2)). The maximum current density with biocathodes in this air-cathode MFC was 1.0 A/m(2), compared to 0.49 A/m(2) originally produced in a two-chamber MFC with an aqueous cathode (with cathode chamber aeration). Single-chamber, air-cathode MFCs with the same biocathodes initially produced higher voltages than those with Pt cathodes, but after several cycles the catalytic activity of the biocathodes was lost. This change in cathode performance resulted from direct exposure of the cathodes to solutions containing high concentrations of organic matter in the single-chamber configuration. Biocathode performance was not impaired in two-chamber designs where the cathode was kept separated from the anode solution. These results demonstrate that direct-air biocathodes can work very well, but only under conditions that minimize heterotrophic growth of microorganisms on the cathodes.

  11. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells.

    PubMed

    Sim, Junyoung; An, Junyeong; Elbeshbishy, Elsayed; Ryu, Hodon; Lee, Hyung-Sool

    2015-11-01

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2O2 conversion efficiency was negligible at 0.3-12%. Current density decreased for passive O2 diffusion to the cathode, but H2O2 conversion efficiency increased by 65%. An MEC equipped with a gas diffusion cathode was operated with acetate medium and domestic wastewater, which presented relatively high H2O2 conversion efficiency from 36% to 47%, although cathode overpotential was fluctuated. Due to different current densities, the maximum H2O2 production rate was 141 mg H2O2/L-h in the MEC fed with acetate medium, but it became low at 6 mg H2O2/L-h in the MEC fed with the wastewater. Our study clearly indicates that improving anodic current density and mitigating membrane fouling would be key parameters for large-scale H2O2-MECs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Carbon black as an alternative cathode material for electrical energy recovery and transfer in a microbial battery.

    PubMed

    Zhang, Xueqin; Guo, Kun; Shen, Dongsheng; Feng, Huajun; Wang, Meizhen; Zhou, Yuyang; Jia, Yufeng; Liang, Yuxiang; Zhou, Mengjiao

    2017-08-01

    Rather than the conventional concept of viewing conductive carbon black (CB) to be chemically inert in microbial electrochemical cells (MECs), here we confirmed the redox activity of CB for its feasibility as an electron sink in the microbial battery (MB). Acting as the cathode of a MB, the solid-state CB electrode showed the highest electron capacity equivalent of 18.58 ± 0.46 C/g for the unsintered one and the lowest capacity of 2.29 ± 0.48 C/g for the one sintered under 100% N 2 atmosphere. The capacity vibrations of CBs were strongly in coincidence with the abundances of C=O moiety caused by different pretreatments and it implied one plausible mechanism based on CB's surface functionality for its electron capturing. Once subjected to electron saturation, CB could be completely regenerated by different strategies in terms of electrochemical discharging or donating electrons to biologically-catalyzed nitrate reduction. Surface characterization also revealed that CB's regeneration fully depended on the reversible shift of C=O moiety, further confirming the functionality-based mechanism for CB's feasibility as the role of MB's cathode. Moreover, resilience tests demonstrated that CB cathode was robust for the multi-cycles charging-discharging operations. These results imply that CB is a promising alternative material for the solid-state cathode in MBs.

  13. Elimination of pyraclostrobin by simultaneous microbial degradation coupled with the Fenton process in microbial fuel cells and the microbial community.

    PubMed

    Zhao, Huanhuan; Kong, Chui-Hua

    2018-06-01

    The elimination of pyraclostrobin by simultaneous microbial degradation and Fenton oxidation was achieved in a microbial fuel cell (MFC) system. After 12 h of incubation, the removal rate of pyraclostrobin was 1.4 mg/L/h at the anode and 1.7 mg/L/h at the cathode. The pyraclostrobin concentration was less than the detection limit (0.1 mg/L) after 72 h at the anode and 24 h at the cathode. The air flow rate, temperature, and pH of the catholyte had significant effects on the generation of H 2 O 2 . The maximum production of H 2 O 2 was 1.2 mg/L after reaction for 20 h during the Fenton process. Microbial community analysis indicated that functional bacteria in the genera Chryseobacterium, Stenotrophomonas, Arcobacter, and Comamonas were predominant in the anodic biofilm. In conclusion, the MFC-Fenton system provides an effective approach for treating environmental contaminants. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Enhancement of electricity production in a mediatorless air-cathode microbial fuel cell using Klebsiella sp. IR21.

    PubMed

    Lee, Yun-Yeong; Kim, Tae Gwan; Cho, Kyung-Suk

    2016-06-01

    A novel dissimilatory iron-reducing bacteria, Klebsiella sp. IR21, was isolated from the anode biofilm of an MFC reactor. Klebsiella sp. IR21 reduced 27.8 % of ferric iron to ferrous iron demonstrating that Klebsiella sp. IR21 has electron transfer ability. Additionally, Klebsiella sp. IR21 generated electricity forming a biofilm on the anode surface. When a pure culture of Klebsiella sp. IR21 was supplied into a single chamber, air-cathode MFC fed with a mixture of glucose and acetate (500 mg L(-1) COD), 40-60 mV of voltage (17-26 mA m(-2) of current density) was produced. Klebsiella sp. IR21 was also utilized as a biocatalyst to improve the electrical performance of a conventional MFC reactor. A single chamber, air-cathode MFC was fed with reject wastewater (10,000 mg L(-1) COD) from a H2 fermentation reactor. The average voltage, current density, and power density were 142.9 ± 25.74 mV, 60.5 ± 11.61 mA m(-2), and 8.9 ± 3.65 mW m(-2), respectively, in the MFC without inoculation of Klebsiella sp. IR21. However, these electrical performances of the MFC were significantly increased to 204.7 ± 40.24 mV, 87.5 ± 17.20 mA m(-2), and 18.6 ± 7.23 mW m(-2), respectively, with inoculation of Klebsiella sp. IR21. The results indicate that Klebsiella sp. IR21 can be utilized as a biocatalyst for enhancement of electrical performance in MFC systems.

  15. Dry Pressed Holey Graphene Composites for Li-air Battery Cathodes

    NASA Astrophysics Data System (ADS)

    Lacey, Steven; Lin, Yi; Hu, Liangbing

    Graphene is considered an ``omnipotent'' material due to its unique structural characteristics and chemical properties. By heating graphene powder in an open-ended tube furnace, a novel compressible carbon material, holey graphene (hG), can be created with controlled porosity and be further decorated with nanosized catalysts to increase electrocatalytic activity. All hG-based materials were characterized using various microscopic and spectroscopic techniques to obtain morphological, topographical, and chemical information as well as to identify any disordered/crystalline phases. In this work, an additive-free dry press method was employed to press the hG composite materials into high mass loading mixed, sandwich, and double-decker Li-air cathode architectures using a hydraulic press. The sandwich and double-decker (i.e. Big Mac) cathode architectures are the first of its kind and can be discharged for more than 200 hours at a current density of 0.2 mA/cm2. The scalable, binderless, and solventless dry press method and unique Li-air cathode architectures presented here greatly advance electrode fabrication possibilities and could promote future energy storage advancements. Support appreciated from the NASA Internships Fellowships Scholarships (NIFS) Program.

  16. One-dimensional manganese-cobalt oxide nanofibres as bi-functional cathode catalysts for rechargeable metal-air batteries

    PubMed Central

    Jung, Kyu-Nam; Hwang, Soo Min; Park, Min-Sik; Kim, Ki Jae; Kim, Jae-Geun; Dou, Shi Xue; Kim, Jung Ho; Lee, Jong-Won

    2015-01-01

    Rechargeable metal-air batteries are considered a promising energy storage solution owing to their high theoretical energy density. The major obstacles to realising this technology include the slow kinetics of oxygen reduction and evolution on the cathode (air electrode) upon battery discharging and charging, respectively. Here, we report non-precious metal oxide catalysts based on spinel-type manganese-cobalt oxide nanofibres fabricated by an electrospinning technique. The spinel oxide nanofibres exhibit high catalytic activity towards both oxygen reduction and evolution in an alkaline electrolyte. When incorporated as cathode catalysts in Zn-air batteries, the fibrous spinel oxides considerably reduce the discharge-charge voltage gaps (improve the round-trip efficiency) in comparison to the catalyst-free cathode. Moreover, the nanofibre catalysts remain stable over the course of repeated discharge-charge cycling; however, carbon corrosion in the catalyst/carbon composite cathode degrades the cycling performance of the batteries. PMID:25563733

  17. Scaled-up dual anode/cathode microbial fuel cell stack for actual ethanolamine wastewater treatment.

    PubMed

    An, Byung-Min; Heo, Yoon; Maitlo, Hubdar-Ali; Park, Joo-Yang

    2016-06-01

    The aim of this work was to develop the scale-up microbial fuel cell technology for actual ethanolamine wastewater treatment, dual anode/cathode MFC stacks connected in series to achieve any desired current, treatment capacity, and volume capacity. However, after feeding actual wastewater into the MFC, maximum power density decreased while the corresponding internal resistance increased. With continuous electricity production, a stack of eight MFCs in series achieved 96.05% of COD removal and 97.30% of ammonia removal at a flow rate of 15.98L/d (HRT 12h). The scaled-up dual anode/cathode MFC stack system in this research was demonstrated to treat actual ETA wastewater with the added benefit of harvesting electricity energy. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Electricity generation in a membrane-less microbial fuel cell with down-flow feeding onto the cathode.

    PubMed

    Zhu, Feng; Wang, Wancheng; Zhang, Xiaoyan; Tao, Guanhong

    2011-08-01

    A novel membrane-less microbial fuel cell (MFC) with down-flow feeding was constructed to generate electricity. Wastewater was fed directly onto the cathode which was horizontally installed in the upper part of the MFC. Oxygen could be utilized readily from the air. The concentration of dissolved oxygen in the influent wastewater had little effect on the power generation. A saturation-type relationship was observed between the initial COD and the power generation. The influent flow rate could affect greatly the power density. Fed by the synthetic glucose wastewater with a COD value of 3500 mg/L at a flow rate of 4.0 mL/min, the developed MFC could produce a maximum power density of 37.4 mW/m(2). Its applicability was further evaluated by the treatment of brewery wastewater. The system could be scaled up readily due to its simple configuration, easy operation and relatively high power density. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Electrochemical struvite precipitation from digestate with a fluidized bed cathode microbial electrolysis cell.

    PubMed

    Cusick, Roland D; Ullery, Mark L; Dempsey, Brian A; Logan, Bruce E

    2014-05-01

    Microbial electrolysis cells (MECs) can be used to simultaneously convert wastewater organics to hydrogen and precipitate struvite, but scale formation at the cathode surface can block catalytic active sites and limit extended operation. To promote bulk phase struvite precipitation and minimize cathode scaling, a two-chamber MEC was designed with a fluidized bed to produce suspended particles and inhibit scale formation on the cathode surface. MEC operation elevated the cathode pH to between 8.3 and 8.7 under continuous flow conditions. Soluble phosphorus removal using digester effluent ranged from 70 to 85% with current generation, compared to 10-20% for the control (open circuit conditions). At low current densities (≤2 mA/m(2)), scouring of the cathode by fluidized particles prevented scale accumulation over a period of 8 days. There was nearly identical removal of soluble phosphorus and magnesium from solution, and an equimolar composition in the collected solids, supporting phosphorus removal by struvite formation. At an applied voltage of 1.0 V, energy consumption from the power supply and pumping (0.2 Wh/L, 7.5 Wh/g-P) was significantly less than that needed by other struvite formation methods based on pH adjustment such as aeration and NaOH addition. In the anode chamber, current generation led to COD oxidation (1.1-2.1 g-COD/L-d) and ammonium removal (7-12 mM) from digestate amended with 1 g/L of sodium acetate. These results indicate that a fluidized bed cathode MEC is a promising method of sustainable electrochemical nutrient and energy recovery method for nutrient rich wastewaters. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Microbial assessment of cabin air quality on commercial airliners

    NASA Technical Reports Server (NTRS)

    La Duc, Myron T.; Stuecker, Tara; Bearman, Gregory; Venkateswaran, Kasthuri

    2005-01-01

    The microbial burdens of 69 cabin air samples collected from commercial airliners were assessed via conventional culture-dependent, and molecular-based microbial enumeration assays. Cabin air samples from each of four separate flights aboard two different carriers were collected via air-impingement. Microbial enumeration techniques targeting DNA, ATP, and endotoxin were employed to estimate total microbial burden. The total viable microbial population ranged from 0 to 3.6 x10 4 cells per 100 liters of air, as assessed by the ATP-assay. When these same samples were plated on R2A minimal medium, anywhere from 2% to 80% of these viable populations were cultivable. Five of the 29 samples examined exhibited higher cultivable counts than ATP derived viable counts, perhaps a consequence of the dormant nature (and thus lower concentration of intracellular ATP) of cells inhabiting these air cabin samples. Ribosomal RNA gene sequence analysis showed these samples to consist of a moderately diverse group of bacteria, including human pathogens. Enumeration of ribosomal genes via quantitative-PCR indicated that population densities ranged from 5 x 10 1 ' to IO 7 cells per 100 liters of air. Each of the aforementioned strategies for assessing overall microbial burden has its strengths and weaknesses; this publication serves as a testament to the power of their use in concert.

  1. Comparative study on power generation of dual-cathode microbial fuel cell according to polarization methods.

    PubMed

    Lee, Kang-yu; Ryu, Wyan-seuk; Cho, Sung-il; Lim, Kyeong-ho

    2015-11-01

    Microbial fuel cells (MFCs) exist in various forms depending on the type of pollutant to be removed and the expected performance. Dual-cathode MFCs, with their simple structure, are capable of removing both organic matter and nitrogen. Moreover, various methods are available for the collection of polarization data, which can be used to calculate the maximum power density, an important factor of MFCs. Many researchers prefer the method of varying the external resistance in a single-cycle due to the short measurement time and high accuracy. This study compared power densities of dual-cathode MFCs in a single-cycle with values calculated over multi-cycles to determine the optimal polarization method. External resistance was varied from high to low and vice versa in the single-cycle, to calculate power density. External resistance was organized in descending order with initial start-up at open circuit voltage (OCV), and then it was organized in descending order again after the initial start-up at 1000 Ω. As a result, power density was underestimated at the anoxic cathode when the external resistance was varied from low to high, and overestimated at the aerobic cathode and anoxic cathode when external resistance at OCV was reduced following initial start-up. In calculating the power densities of dual-cathode MFCs, this paper recommends the method of gradually reducing the external resistance after initial start-up with high external resistance. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. A membrane-free baffled microbial fuel cell for cathodic reduction of Cu(II) with electricity generation.

    PubMed

    Tao, Hu-Chun; Li, Wei; Liang, Min; Xu, Nan; Ni, Jin-Ren; Wu, Wei-Min

    2011-04-01

    A membrane-free baffled microbial fuel cell (MFC) was developed to treat synthetic Cu(II) sulfate containing wastewater in cathode chamber and synthetic glucose-containing wastewater fed to anode chamber. Maximum power density of 314 mW/m(3) with columbic efficiency of 5.3% was obtained using initial Cu(2+) concentration of 6400 mg/L. Higher current density favored the cathodic reduction of Cu(2+), and removal of Cu(2+) by 70% was observed within 144 h using initial concentration of 500 mg/L. Powder X-ray diffraction (XRD) analysis indicated that the Cu(2+) was reduced to Cu(2)O or Cu(2)O plus Cu which deposited on the cathode, and the deficient cathodic reducibility resulted in the formation of Cu(4)(OH)(6)SO(4) at high initial Cu(2+) concentration (500-6400 mg/L). This study suggested a novel low-cost approach to remove and recover Cu(II) from Cu(2+)-containing wastewater using MFC-type reactor. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. High-Thermal- and Air-Stability Cathode Material with Concentration-Gradient Buffer for Li-Ion Batteries.

    PubMed

    Shi, Ji-Lei; Qi, Ran; Zhang, Xu-Dong; Wang, Peng-Fei; Fu, Wei-Gui; Yin, Ya-Xia; Xu, Jian; Wan, Li-Jun; Guo, Yu-Guo

    2017-12-13

    Delivery of high capacity with high thermal and air stability is a great challenge in the development of Ni-rich layered cathodes for commercialized Li-ion batteries (LIBs). Herein we present a surface concentration-gradient spherical particle with varying elemental composition from the outer end LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM) to the inner end LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA). This cathode material with the merit of NCM concentration-gradient protective buffer and the inner NCA core shows high capacity retention of 99.8% after 200 cycles at 0.5 C. Furthermore, this cathode material exhibits much improved thermal and air stability compared with bare NCA. These results provide new insights into the structural design of high-performance cathodes with high energy density, long life span, and storage stability materials for LIBs in the future.

  4. Power generation in microbial fuel cells using platinum group metal-free cathode catalyst: Effect of the catalyst loading on performance and costs

    NASA Astrophysics Data System (ADS)

    Santoro, Carlo; Kodali, Mounika; Herrera, Sergio; Serov, Alexey; Ieropoulos, Ioannis; Atanassov, Plamen

    2018-02-01

    Platinum group metal-free (PGM-free) catalyst with different loadings was investigated in air breathing electrodes microbial fuel cells (MFCs). Firstly, the electrocatalytic activity towards oxygen reduction reaction (ORR) of the catalyst was investigated by rotating ring disk electrode (RRDE) setup with different catalyst loadings. The results showed that higher loading led to an increased in the half wave potential and the limiting current and to a further decrease in the peroxide production. The electrons transferred also slightly increased with the catalyst loading up to the value of ≈3.75. This variation probably indicates that the catalyst investigated follow a 2x2e- transfer mechanism. The catalyst was integrated within activated carbon pellet-like air-breathing cathode in eight different loadings varying between 0.1 mgcm-2 and 10 mgcm-2. Performance were enhanced gradually with the increase in catalyst content. Power densities varied between 90 ± 9 μWcm-2 and 262 ± 4 μWcm-2 with catalyst loading of 0.1 mgcm-2 and 10 mgcm-2 respectively. Cost assessments related to the catalyst performance are presented. An increase in catalyst utilization led to an increase in power generated with a substantial increase in the whole costs. Also a decrease in performance due to cathode/catalyst deterioration over time led to a further increase in the costs.

  5. Power generation in microbial fuel cells using platinum group metal-free cathode catalyst: Effect of the catalyst loading on performance and costs.

    PubMed

    Santoro, Carlo; Kodali, Mounika; Herrera, Sergio; Serov, Alexey; Ieropoulos, Ioannis; Atanassov, Plamen

    2018-02-28

    Platinum group metal-free (PGM-free) catalyst with different loadings was investigated in air breathing electrodes microbial fuel cells (MFCs). Firstly, the electrocatalytic activity towards oxygen reduction reaction (ORR) of the catalyst was investigated by rotating ring disk electrode (RRDE) setup with different catalyst loadings. The results showed that higher loading led to an increased in the half wave potential and the limiting current and to a further decrease in the peroxide production. The electrons transferred also slightly increased with the catalyst loading up to the value of ≈3.75. This variation probably indicates that the catalyst investigated follow a 2x2e - transfer mechanism. The catalyst was integrated within activated carbon pellet-like air-breathing cathode in eight different loadings varying between 0.1 mgcm -2 and 10 mgcm -2 . Performance were enhanced gradually with the increase in catalyst content. Power densities varied between 90 ± 9 μWcm -2 and 262 ± 4 μWcm -2 with catalyst loading of 0.1 mgcm -2 and 10 mgcm -2 respectively. Cost assessments related to the catalyst performance are presented. An increase in catalyst utilization led to an increase in power generated with a substantial increase in the whole costs. Also a decrease in performance due to cathode/catalyst deterioration over time led to a further increase in the costs.

  6. [Effect of temperature on performance of microbial fuel cell using beer wastewater].

    PubMed

    Wang, Xin; Feng, Yu-Jie; Qu, You-Peng; Li, Dong-Mei; Li, He; Ren, Nan-Qi

    2008-11-01

    The effects of temperature on performance and biological community structure were investigated in air-cathode microbial fuel cells (MFCs) using beer wastewater amended with 50 mmol/L phosphate buffer solution (PBS). The maximum power density decreased from 483 mW/m2 to 435 mW/m2 when the temperature varied from 30 degrees C to 20 degrees C, meanwhile just a little decreasing on coulombic efficiency and the COD removal rate were observed. Decreasing of temperature resulted in effects both on cathode potential and anode potential, but cathode potential behaved much more sensitive to temperature. The half-saturation constants (Ks) obtained from the fit of Monod-type equation were 228 mg/L (30 degrees C) and 293 mg/L (20 degrees C) respectively. Denaturing gradient gel electrophoresis (DGGE) analysis indicated that operating temperature not only affected the predominant population of the anodic bacterial community, but also had a great impact on the diversity of the cathodic microbial population.

  7. Air plasma spray processing and electrochemical characterization of SOFC composite cathodes

    NASA Astrophysics Data System (ADS)

    White, B. D.; Kesler, O.; Rose, Lars

    Air plasma spraying has been used to produce porous composite cathodes containing (La 0.8Sr 0.2) 0.98MnO 3- y (LSM) and yttria-stabilized zirconia (YSZ) for use in solid oxide fuel cells (SOFCs). Preliminary investigations focused on determining the range of plasma conditions under which each of the individual materials could be successfully deposited. A range of conditions was thereby determined that was suitable for the deposition of a composite cathode from pre-mixed LSM and YSZ powders. A number of composite cathodes were produced using different combinations of parameter values within the identified range according to a Uniform Design experimental grid. Coatings were then characterized for composition and microstructure using EDX and SEM. As a result of these tests, combinations of input parameter values were identified that are best suited to the production of coatings with microstructures appropriate for use in SOFC composite cathodes. A selection of coatings representative of the types of observed microstructures were then subjected to electrochemical testing to evaluate the performance of these cathodes. From these tests, it was found that, in general, the coatings that appeared to have the most suitable microstructures also had the highest electrochemical performances, provided that the deposition efficiency of both phases was sufficiently high.

  8. Performance of MnO2 Crystallographic Phases in Rechargeable Lithium-Air Oxygen Cathode

    NASA Astrophysics Data System (ADS)

    Oloniyo, Olubukun; Kumar, Senthil; Scott, Keith

    2012-05-01

    Manganese dioxide (MnO2) has been shown to be effective for improving the efficiency of cathodes in lithium-air cells. Different crystallographic phases including α-, β-, and γ-MnO2 nanowires, α-MnO2 nanospheres, and α-MnO2 nanowires on carbon ( α-MnO2/C) were synthesized using the hydrothermal method. Their physical properties were examined using x-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area measurements, and scanning electron microscopy (SEM) and found to be in agreement with the literature. Electrochemical properties of the synthesized catalyst particles were investigated by fabricating cathodes and testing them in a lithium-air cell with lithium hexafluorophosphate in propylene carbonate (LiPF6/PC) and tetra(ethylene glycol)dimethyl ether (LiTFSi/TEGDME) electrolytes. α-MnO2 had the highest discharge capacity in the LiTFSi/TEGDME electrolyte (2500 mAh/g), whilst α-MnO2/C in LiPF6/PC showed a significantly higher discharge capacity of 11,000 mAh/g based on total mass of the catalytic cathode. However, the latter showed poor capacity retention compared with γ-MnO2 nanowires, which was stable for up to 30 cycles. The reported discharge capacity is higher than recorded in previous studies on lithium-air cells.

  9. A novel carbon black graphite hybrid air-cathode for efficient hydrogen peroxide production in bioelectrochemical systems

    NASA Astrophysics Data System (ADS)

    Li, Nan; An, Jingkun; Zhou, Lean; Li, Tian; Li, Junhui; Feng, Cuijuan; Wang, Xin

    2016-02-01

    Carbon black and graphite hybrid air-cathode is proved to be effective for H2O2 production in bioelectrochemical systems. The optimal mass ratio of carbon black to graphite is 1:5 with the highest H2O2 yield of 11.9 mg L-1 h-1 cm-2 (12.3 mA cm-2). Continuous flow is found to improve the current efficiency due to the avoidance of H2O2 accumulation. In the biological system, the highest H2O2 yield reaches 3.29 mg L-1h-1 (0.079 kg m-3day-1) with a current efficiency of 72%, which is higher than the abiotic system at the same current density. H2O2 produced in this system is mainly from the oxygen diffused through this air-cathode (>66%), especially when a more negative cathode potential is applied (94% at -1.0 V). This hybrid air-cathode has advantages of high H2O2 yield, high current density and no need of aeration, which make the synthesis of H2O2 more efficient and economical.

  10. Enhancing substrate utilization and power production of a microbial fuel cell with nitrogen-doped carbon aerogel as cathode catalyst.

    PubMed

    Tardy, Gábor Márk; Lóránt, Bálint; Lóka, Máté; Nagy, Balázs; László, Krisztina

    2017-07-01

    Catalytic efficiency of a nitrogen-doped, mesoporous carbon aerogel cathode catalyst was investigated in a two-chambered microbial fuel cell (MFC) applying graphite felt as base material for cathode and anode, utilizing peptone as carbon source. This mesoporous carbon aerogel containing catalyst layer on the cathode increased the maximum power density normalized to the anode volume to 2.7 times higher compared to the maximum power density obtained applying graphite felt cathode without the catalyst layer. At high (2 and 3) cathode/anode volume ratios, maximum power density exceeded 40 W m -3 . At the same time, current density and specific substrate utilization rate increased by 58% resulting in 31.9 A m -3 and 18.8 g COD m -3  h -1 , respectively (normalized to anode volume). Besides the increase of the power and the rate of biodegradation, the investigated catalyst decreased the internal resistance from the range of 450-600 to 350-370 Ω. Although Pt/C catalyst proved to be more efficient, a considerable decrease in the material costs might be achieved by substituting it with nitrogen-doped carbon aerogel in MFCs. Such cathode still displays enhanced catalytic effect.

  11. Simplifying microbial electrosynthesis reactor design.

    PubMed

    Giddings, Cloelle G S; Nevin, Kelly P; Woodward, Trevor; Lovley, Derek R; Butler, Caitlyn S

    2015-01-01

    Microbial electrosynthesis, an artificial form of photosynthesis, can efficiently convert carbon dioxide into organic commodities; however, this process has only previously been demonstrated in reactors that have features likely to be a barrier to scale-up. Therefore, the possibility of simplifying reactor design by both eliminating potentiostatic control of the cathode and removing the membrane separating the anode and cathode was investigated with biofilms of Sporomusa ovata. S. ovata reduces carbon dioxide to acetate and acts as the microbial catalyst for plain graphite stick cathodes as the electron donor. In traditional 'H-cell' reactors, where the anode and cathode chambers were separated with a proton-selective membrane, the rates and columbic efficiencies of microbial electrosynthesis remained high when electron delivery at the cathode was powered with a direct current power source rather than with a potentiostat-poised cathode utilized in previous studies. A membrane-less reactor with a direct-current power source with the cathode and anode positioned to avoid oxygen exposure at the cathode, retained high rates of acetate production as well as high columbic and energetic efficiencies. The finding that microbial electrosynthesis is feasible without a membrane separating the anode from the cathode, coupled with a direct current power source supplying the energy for electron delivery, is expected to greatly simplify future reactor design and lower construction costs.

  12. A Single-Use Paper-Shaped Microbial Fuel Cell for Rapid Aqueous Biosensing.

    PubMed

    Zuo, Kuichang; Liu, Han; Zhang, Qiaoying; Liang, Peng; Huang, Xia; Vecitis, Chad D

    2015-06-22

    The traditional chamber-based microbial fuel cell (MFC) often has the disadvantages of high ohmic resistance, large volume requirements, and delayed start-up. In this study, paper-shaped MFCs utilizing a porous carbon anode, a solid Ag2 O-coated carbon cathode, and a micrometer-thin porous polyvinylidene fluoride (PVDF) separator are investigated to address the classical MFC issues. The Ag2 O-coated cathode has a low overpotential of 0.06 V at a reducing current of 1 mA compared to a Pt-air cathode. Rapid inoculation by filtration results in an instantaneous power density of 92 mW m(-2) with an internal resistance of 162 Ω. Integrated current over the first 30 min of operation has a linear relation with microbial concentration. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Metalized, three-dimensional structured oxygen cathode materials for lithium/air batteries and method for making and using the same

    DOEpatents

    Xing, Weibing; Buettner-Garrett, Josh

    2017-04-18

    This disclosure relates generally to cathode materials for electrochemical energy cells, more particularly to metal/air electrochemical energy cell cathode materials containing silver vanadium oxide and methods of making and using the same. The metal/air electrochemical energy cell can be a lithium/air electrochemical energy cell. Moreover the silver vanadium oxide can be a catalyst for one or more of oxidation and reduction processes of the electrochemical energy cell.

  14. Connecting Water Quality With Air Quality Through Microbial Aerosols

    NASA Astrophysics Data System (ADS)

    Dueker, M. Elias

    Aerosol production from surface waters results in the transfer of aquatic materials (including nutrients and bacteria) to air. These materials can then be transported by onshore winds to land, representing a biogeochemical connection between aquatic and terrestrial systems not normally considered. In urban waterfront environments, this transfer could result in emissions of pathogenic bacteria from contaminated waters. Despite the potential importance of this link, sources, near-shore deposition, identity and viability of microbial aerosols are largely uncharacterized. This dissertation focuses on the environmental and biological mechanisms that define this water-air connection, as a means to build our understanding of the biogeochemical, biogeographical, and public health implications of the transfer of surface water materials to the near-shore environment in both urban and non-urban environments. The effects of tidal height, wind speed and fog on coastal aerosols and microbial content were first quantified on a non-urban coast of Maine, USA. Culture-based, culture-independent, and molecular methods were used to simultaneously sample microbial aerosols while monitoring meteorological parameters. Aerosols at this site displayed clear marine influence and high concentrations of ecologically-relevant nutrients. Coarse aerosol concentrations significantly increased with tidal height, onshore wind speed, and fog presence. Tidal height and fog presence did not significantly influence total microbial aerosol concentrations, but did have a significant effect on culturable microbial aerosol fallout. Molecular analyses of the microbes settling out of near-shore aerosols provided further evidence of local ocean to terrestrial transport of microbes. Aerosol and surface ocean bacterial communities shared species and in general were dominated by organisms previously sampled in marine environments. Fog presence strengthened the microbial connection between water and land through

  15. CO2 Fixation, Lipid Production, and Power Generation by a Novel Air-Lift-Type Microbial Carbon Capture Cell System.

    PubMed

    Hu, Xia; Liu, Baojun; Zhou, Jiti; Jin, Ruofei; Qiao, Sen; Liu, Guangfei

    2015-09-01

    An air-lift-type microbial carbon capture cell (ALMCC) was constructed for the first time by using an air-lift-type photobioreactor as the cathode chamber. The performance of ALMCC in fixing high concentration of CO2, producing energy (power and biodiesel), and removing COD together with nutrients was investigated and compared with the traditional microbial carbon capture cell (MCC) and air-lift-type photobioreactor (ALP). The ALMCC system produced a maximum power density of 972.5 mW·m(-3) and removed 86.69% of COD, 70.52% of ammonium nitrogen, and 69.24% of phosphorus, which indicate that ALMCC performed better than MCC in terms of power generation and wastewater treatment efficiency. Besides, ALMCC demonstrated 9.98- and 1.88-fold increases over ALP and MCC in the CO2 fixation rate, respectively. Similarly, the ALMCC significantly presented a higher lipid productivity compared to those control reactors. More importantly, the preliminary analysis of energy balance suggested that the net energy of the ALMCC system was significantly superior to other systems and could theoretically produce enough energy to cover its consumption. In this work, the established ALMCC system simultaneously achieved the high level of CO2 fixation, energy recycle, and municipal wastewater treatment effectively and efficiently.

  16. Solid oxide fuel cell power plant having a fixed contact oxidation catalyzed section of a multi-section cathode air heat exchanger

    DOEpatents

    Saito, Kazuo; Lin, Yao

    2015-02-17

    The multi-section cathode air heat exchanger (102) includes at least a first heat exchanger section (104), and a fixed contact oxidation catalyzed section (126) secured adjacent each other in a stack association. Cool cathode inlet air flows through cool air channels (110) of the at least first (104) and oxidation catalyzed sections (126). Hot anode exhaust flows through hot air channels (124) of the oxidation catalyzed section (126) and is combusted therein. The combusted anode exhaust then flows through hot air channels (112) of the first section (104) of the cathode air heat exchanger (102). The cool and hot air channels (110, 112) are secured in direct heat exchange relationship with each other so that temperatures of the heat exchanger (102) do not exceed 800.degree. C. to minimize requirements for using expensive, high-temperature alloys.

  17. Nanotubular MnO2/graphene oxide composites for the application of open air-breathing cathode microbial fuel cells.

    PubMed

    Gnana Kumar, G; Awan, Zahoor; Suk Nahm, Kee; Xavier, J Stanley

    2014-03-15

    Nanotubular shaped α-MnO2/graphene oxide nanocomposites were synthesized via a simple, cost and time efficient hydrothermal method. The growth of hollow structured MnO2 nanotubes preferentially occurred along the [001] direction as evidenced from the morphological and structural characterizations. The tunnels of α-MnO2 nanotubes easily accommodated the molecular oxygen and exhibited excellent catalytic activity towards the oxygen reduction reaction over the rod structure and was further enhanced with the effective carbon support graphene oxide. The MnO2 nanotubes/graphene oxide nanocomposite modified electrode exhibited a maximum power density of 3359 mW m(-2) which is 7.8 fold higher than that of unmodified electrode and comparable with the Pt/C modified electrode. The microbial fuel cell equipped with MnO2 nanotubes/graphene oxide nanocomposite modified cathode exhibited quick start up and excellent durability over the studied electrodes and is attributed to the high surface area and number of active sites. These findings not only provide the fundamental studies on carbon supported low-dimensional transition-metal oxides but also open up the new possibilities of their applications in green energy devices. © 2013 Elsevier B.V. All rights reserved.

  18. Efficient polymer light-emitting diode with air-stable aluminum cathode

    NASA Astrophysics Data System (ADS)

    Abbaszadeh, D.; Wetzelaer, G. A. H.; Doumon, N. Y.; Blom, P. W. M.

    2016-03-01

    The fast degradation of polymer light-emitting diodes (PLEDs) in ambient conditions is primarily due to the oxidation of highly reactive metals, such as barium or calcium, which are used as cathode materials. Here, we report the fabrication of PLEDs using an air-stable partially oxidized aluminum (AlOx) cathode. Usually, the high work function of aluminum (4.2 eV) imposes a high barrier for injecting electrons into the lowest unoccupied molecular orbital (LUMO) of the emissive polymer (2.9 eV below the vacuum level). By partially oxidizing aluminum, its work function is decreased, but not sufficiently low for efficient electron injection. Efficient injection is obtained by inserting an electron transport layer of poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT), which has its LUMO at 3.3 eV below vacuum, between the AlOx cathode and the emissive polymer. The intermediate F8BT layer not only serves as a hole-blocking layer but also provides an energetic staircase for electron injection from AlOx into the emissive layer. PLEDs with an AlOx cathode and F8BT interlayer exhibit a doubling of the efficiency as compared to conventional Ba/Al PLEDs, and still operate even after being kept in ambient atmosphere for one month without encapsulation.

  19. Enhancing the performance of single-chambered microbial fuel cell using manganese/palladium and zirconium/palladium composite cathode catalysts.

    PubMed

    Jadhav, Dipak A; Deshpande, Parag A; Ghangrekar, Makarand M

    2017-08-01

    Application of ZrO 2 , MnO 2 , palladium, palladium-substituted-zirconium oxide (Zr 0.98 Pd 0.02 O 2 ) and palladium-substituted-manganese oxide (Mn 0.98 Pd 0.02 O 2 ) cathode catalysts in a single-chambered microbial fuel cell (MFC) was explored. The highest power generation (1.28W/m 3 ) was achieved in MFC with Mn 0.98 Pd 0.02 O 2 catalyst, which was higher than that with MnO 2 (0.58W/m 3 ) alone; whereas, MFC having Zr 0.98 Pd 0.02 O 2 catalyzed cathode and non-catalyzed cathode produced powers of 1.02 and 0.23W/m 3 , respectively. Also, low-cost zirconium-palladium-composite showed better catalytic activity and capacitance over ZrO 2 with 20A/m 3 current production and demonstrated its suitability for MFC applications. Cyclic voltammetry analyses showed higher well-defined redox peaks in composite catalysts (Mn/Zr-Pd-C) over other catalyzed MFCs containing MnO 2 or ZrO 2 . Electrochemical behaviour of composite catalysts on cathode showed higher availability of adsorption sites for oxygen reduction and, hence, enhanced the rate of cathodic reactions. Thus, Mn/Zr-Pd-C-based composite catalysts exhibited superior cathodic performance and could be proposed as alternatives to costly Pd-catalyst for field applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Efficient bioconversion of organic wastes to high optical activity of l-lactic acid stimulated by cathode in mixed microbial consortium.

    PubMed

    Xue, Gang; Lai, Sizhou; Li, Xiang; Zhang, Wenjuan; You, Jiguang; Chen, Hong; Qian, Yajie; Gao, Pin; Liu, Zhenhong; Liu, Yanan

    2017-12-12

    Lactic acid is one of the emerging top biomass derived platform chemicals that can be fermented from organic wastes. This study evaluated the potential of Cathodic Electro-Fermentation (CEF) as a novel approach to enhance the yield of high optical activity (OA) of l-lactic acid from organic wastes using mixed microbial consortium. The fermentation process was stimulated through the cathode applied with -100 mV versus standard hydrogen electrode (SHE), which contributed to 4.73 times higher lactic acid productivity (0.6578 g L -1 h -1 ) compared to that in the open circuit control (0.1392 g L -1 h -1 ), and an improved OA of l-lactic acid was also observed (42.3% vs. 3.6% of the open circuit control). The study elucidated that the optimal voltage at -100 mV promoted the conversion of pyruvate to l-lactate by 77.9% compared to the Blank, which triggered the generation of l-lactic acid to occur rapidly even at low concentration of pyruvate. The significant variation of microbial community in family- and genus-level distributions were observed in CEF system. Furthermore, the open-circuit operation test demonstrated that the cathode providing in-situ electron supply was essential to achieve high efficient bioconversion of organic wastes to lactic acid. Our work highlights the feasibility of CEF to steer high value-added fermentation products deriving from organic wastes by the mixed microbial consortium. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Study of Stable Cathodes and Electrolytes for High Specific Density Lithium-Air Battery

    NASA Technical Reports Server (NTRS)

    Hernandez-Lugo, Dionne M.; Wu, James; Bennett, William; Ming, Yu; Zhu, Yu

    2015-01-01

    Future NASA missions require high specific energy battery technologies, greater than 400 Wh/kg. Current NASA missions are using "state-of-the-art" (SOA) Li-ion batteries (LIB), which consist of a metal oxide cathode, a graphite anode and an organic electrolyte. NASA Glenn Research Center is currently studying the physical and electrochemical properties of the anode-electrolyte interface for ionic liquid based Li-air batteries. The voltage-time profiles for Pyr13FSI and Pyr14TFSI ionic liquids electrolytes studies on symmetric cells show low over-potentials and no dendritic lithium morphology. Cyclic voltammetry measurements indicate that these ionic liquids have a wide electrochemical window. As a continuation of this work, sp2 carbon cathode and these low flammability electrolytes were paired and the physical and electrochemical properties were studied in a Li-air battery system under an oxygen environment.

  2. Efficient polymer light-emitting diode with air-stable aluminum cathode

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abbaszadeh, D.; Dutch Polymer Institute, P.O. Box 902, 5600 AX Eindhoven; Wetzelaer, G. A. H.

    2016-03-07

    The fast degradation of polymer light-emitting diodes (PLEDs) in ambient conditions is primarily due to the oxidation of highly reactive metals, such as barium or calcium, which are used as cathode materials. Here, we report the fabrication of PLEDs using an air-stable partially oxidized aluminum (AlO{sub x}) cathode. Usually, the high work function of aluminum (4.2 eV) imposes a high barrier for injecting electrons into the lowest unoccupied molecular orbital (LUMO) of the emissive polymer (2.9 eV below the vacuum level). By partially oxidizing aluminum, its work function is decreased, but not sufficiently low for efficient electron injection. Efficient injection is obtainedmore » by inserting an electron transport layer of poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3] thiadiazol-4,8-diyl)] (F8BT), which has its LUMO at 3.3 eV below vacuum, between the AlO{sub x} cathode and the emissive polymer. The intermediate F8BT layer not only serves as a hole-blocking layer but also provides an energetic staircase for electron injection from AlO{sub x} into the emissive layer. PLEDs with an AlO{sub x} cathode and F8BT interlayer exhibit a doubling of the efficiency as compared to conventional Ba/Al PLEDs, and still operate even after being kept in ambient atmosphere for one month without encapsulation.« less

  3. Enhanced hydrogen production in microbial electrolysis cell with 3D self-assembly nickel foam-graphene cathode.

    PubMed

    Cai, Weiwei; Liu, Wenzong; Han, Jinglong; Wang, Aijie

    2016-06-15

    In comparison to precious metal catalyst especially Platinum (Pt), nickel foam (NF) owned cheap cost and unique three-dimensional (3D) structure, however, it was scarcely applied as cathode material in microbial electrolysis cell (MEC) as the intrinsic laggard electrochemical activity for hydrogen recovery. In this study, a self-assembly 3D nickel foam-graphene (NF-G) cathode was fabricated by facile hydrothermal approach for hydrogen evolution in MECs. Electrochemical analysis (linear scan voltammetry and electrochemical impedance spectroscopy) revealed the improved electrochemical activity and effective mass diffusion after coating with graphene. NF-G as cathode in MEC showed a significant enhancement in hydrogen production rate compared with nickel foam at a variety of biases. Noticeably, NF-G showed a comparable averaged hydrogen production rate (1.31 ± 0.07 mL H2 mL(-1) reactor d(-1)) to Platinum/carbon (Pt/C) (1.32 ± 0.07 mL H2 mL(-1) reactor d(-1)) at 0.8 V. Profitable energy recovery could be achieved by NF-G cathode at higher applied voltage, which performed the best hydrogen yield of 3.27 ± 0.16 mol H2 mol(-1) acetate at 0.8 V and highest energy efficiency of 185.92 ± 6.48% at 0.6 V. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Electrochemically exfoliated graphene anodes with enhanced biocurrent production in single-chamber air-breathing microbial fuel cells.

    PubMed

    Najafabadi, Amin Taheri; Ng, Norvin; Gyenge, Előd

    2016-07-15

    Microbial fuel cells (MFCs) present promising options for environmentally sustainable power generation especially in conjunction with waste water treatment. However, major challenges remain including low power density, difficult scale-up, and durability of the cell components. This study reports enhanced biocurrent production in a membrane-free MFC, using graphene microsheets (GNs) as anode and MnOx catalyzed air cathode. The GNs are produced by ionic liquid assisted simultaneous anodic and cathodic electrochemical exfoliation of iso-molded graphite electrodes. The GNs produced by anodic exfoliation increase the MFC peak power density by over 300% compared to plain carbon cloth (i.e., 2.85Wm(-2) vs 0.66Wm(-2), respectively), and by 90% compared to conventional carbon black (i.e., Vulcan XC-72) anode. These results exceed previously reported power densities for graphene-containing MFC anodes. The fuel cell polarization results are corroborated by electrochemical impedance spectroscopy indicating three times lower charge transfer resistance for the GN anode. Material characterizations suggest that the best performing GN samples were of relatively smaller size (~500nm), with higher levels of ionic liquid induced surface functionalization during the electrochemical exfoliation process. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Regenerable Nickel-Functionalized Activated Carbon Cathodes Enhanced by Metal Adsorption to Improve Hydrogen Production in Microbial Electrolysis Cells.

    PubMed

    Kim, Kyoung-Yeol; Yang, Wulin; Logan, Bruce E

    2018-06-07

    While nickel is a good alternative to platinum as a catalyst for the hydrogen evolution reaction, it is desirable to reduce the amount of nickel needed for cathodes in microbial electrolysis cells (MECs). Activated carbon (AC) was investigated as a cathode base structure for Ni as it is inexpensive and an excellent adsorbent for Ni, and it has a high specific surface area. AC nickel-functionalized electrodes (AC-Ni) were prepared by incorporating Ni salts into AC by adsorption, followed by cathode fabrication using a phase inversion process using a poly(vinylidene fluoride) (PVDF) binder. The AC-Ni cathodes had significantly higher (∼50%) hydrogen production rates than controls (plain AC) in smaller MECs (static flow conditions) over 30 days of operation, with no performance decrease over time. In larger MECs with catholyte recirculation, the AC-Ni cathode produced a slightly higher hydrogen production rate (1.1 ± 0.1 L-H 2 /L reactor /day) than MECs with Ni foam (1.0 ± 0.1 L-H 2 /L reactor /day). Ni dissolution tests showed that negligible amounts of Ni were lost into the electrolyte at pHs of 7 or 12, and the catalytic activity was restored by simple readsorption using a Ni salt solution when Ni was partially removed by an acid wash.

  6. COD removal characteristics in air-cathode microbial fuel cells.

    PubMed

    Zhang, Xiaoyuan; He, Weihua; Ren, Lijiao; Stager, Jennifer; Evans, Patrick J; Logan, Bruce E

    2015-01-01

    Exoelectrogenic microorganisms in microbial fuel cells (MFCs) compete with other microorganisms for substrate. In order to understand how this affects removal rates, current generation, and coulombic efficiencies (CEs), substrate removal rates were compared in MFCs fed a single, readily biodegradable compound (acetate) or domestic wastewater (WW). Removal rates based on initial test conditions fit first-order kinetics, but rate constants varied with circuit resistance. With filtered WW (100Ω), the rate constant was 0.18h(-)(1), which was higher than acetate or filtered WW with an open circuit (0.10h(-)(1)), but CEs were much lower (15-24%) than acetate. With raw WW (100Ω), COD removal proceeded in two stages: a fast removal stage with high current production, followed by a slower removal with little current. While using MFCs increased COD removal rate due to current generation, secondary processes will be needed to reduce COD to levels suitable for discharge. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Binder-free NiFe2O4/C nanofibers as air cathodes for Li-O2 batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Wang, Chengyi; Chen, Ya-Nan; Wang, Xin-Gai; Xie, Zhaojun; Zhou, Zhen

    2018-02-01

    Rechargeable Li-O2 batteries have aroused much attention for their high energy density. However, the poor rechargeability and low efficiency hinder their practical applications. To solve these issues, free-standing carbon films combined with high-activity NiFe2O4 catalysts are prepared by electrospinning method, and directly used as air cathodes for Li-O2 batteries. The obtained films have 3D networks formed by stacking and interlacing massive nanofibers with uniformly dispersed NiFe2O4 nanoparticles on them. The Li-O2 batteries with such binder-free air cathodes show low charging overpotential even comparable to precious metal cathodes, and can sustain excellent discharge/charge cyclic stability. The unique structure and binder-free superiority greatly facilitates the Li+ and O2 diffusion, accelerates the decomposition of Li2O2, and avoid the disturbance of polymer binders.

  8. Non-Aqueous Primary Li-Air Flow Battery and Optimization of its Cathode through Experiment and Modeling.

    PubMed

    Kim, Byoungsu; Takechi, Kensuke; Ma, Sichao; Verma, Sumit; Fu, Shiqi; Desai, Amit; Pawate, Ashtamurthy S; Mizuno, Fuminori; Kenis, Paul J A

    2017-09-22

    A primary Li-air battery has been developed with a flowing Li-ion free ionic liquid as the recyclable electrolyte, boosting power capability by promoting superoxide diffusion and enhancing discharge capacity through separately stored discharge products. Experimental and computational tools are used to analyze the cathode properties, leading to a set of parameters that improve the discharge current density of the non-aqueous Li-air flow battery. The structure and configuration of the cathode gas diffusion layers (GDLs) are systematically modified by using different levels of hot pressing and the presence or absence of a microporous layer (MPL). These experiments reveal that the use of thinner but denser MPLs is key for performance optimization; indeed, this leads to an improvement in discharge current density. Also, computational results indicate that the extent of electrolyte immersion and porosity of the cathode can be optimized to achieve higher current density. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Nitrogen removal and electricity production at a double-chamber microbial fuel cell with cathode nitrite denitrification.

    PubMed

    Yu, Yangyang; Zhao, Jianqiang; Wang, Sha; Zhao, Huimin; Ding, Xiaoqian; Gao, Kun

    2017-12-01

    Double-chamber microbial fuel cell was applied to investigate the performance of the electricity production and nitrite denitrification through feeding nitrite into the cathode. Factors influencing denitrification performance and power production, such as external resistance, influent nitrite concentration and Nitrite Oxygen Bacteria inhibitors, were studied. The results show that when the concentration of nitrite nitrogen and external resistance were 100 mg L -1 and 10 Ω, respectively, the nitrite denitrification reached the best state. The NaN 3 can inhibit nitrite oxidation effectively; meanwhile, the nitrite denitrification with N 2 O as the final products was largely improved. The [Formula: see text] was reduced to [Formula: see text], causing the cathode denitrification coulombic efficiency to exceed 100%. In chemoautotrophic bio-nitrification, microorganisms may utilize H 2 O to oxidize nitrite under anaerobic conditions. Proteobacteria might play a major role in the process of denitrification in MFC.

  10. Isolation and bioelectrochemical characterization of novel fungal sources with oxidasic activity applied in situ for the cathodic oxygen reduction in microbial fuel cells.

    PubMed

    Morant, Kyriale Vasconcelos; da Silva, Paulo Henrique; de Campos-Takaki, Galba Maria; Hernández, Camilo Enrique La Rotta

    2014-11-01

    Brazilian filamentous fungi Rhizopus sp. (SIS-31), Aspergillus sp. (SIS-18) and Penicillium sp. (SIS-21), sources of oxidases were isolated from Caatinga's soils and applied during the in situ cathodic oxygen reduction in fuel cells. All strains were cultivated in submerged cultures using an optimized saline medium enriched with 10 g L(-1) of glucose, 3.0 g L(-1) of peptone and 0.0005 g L(-1) of CuSO4 as enzyme inducer. Parameters of oxidase activity, glucose consumption and microbial growth were evaluated. In-cell experiments evaluated by chronoamperometry were performed and two different electrode compositions were also compared. Maximum current densities of 125.7, 98.7 and 11.5 μA cm(-2) were observed before 24 h and coulombic efficiencies of 56.5, 46.5 and 23.8% were obtained for SIS-31, SIS-21 and SIS-18, respectively. Conversely, maximum power outputs of 328.73, 288.80 and 197.77 mW m(-3) were observed for SIS-18, SIS-21 and SIS-31, respectively. This work provides the primary experimental evidences that fungi isolated from the Caatinga region in Brazil can serve as efficient biocatalysts during the oxygen reduction in air-cathodes to improve electricity generation in MFCs. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Performance assessment of aeration and radial oxygen loss assisted cathode based integrated constructed wetland-microbial fuel cell systems.

    PubMed

    Srivastava, Pratiksha; Dwivedi, Saurabh; Kumar, Naresh; Abbassi, Rouzbeh; Garaniya, Vikram; Yadav, Asheesh Kumar

    2017-11-01

    The present study explores low-cost cathode development possibility using radial oxygen loss (ROL) of Canna indica plants and intermittent aeration (IA) for wastewater treatment and electricity generation in constructed wetland-microbial fuel cell (CW-MFC) system. Two CW-MFC microcosms were developed. Amongst them, one microcosm was planted with Canna indica plants for evaluating the ROL dependent cathode reaction (CW-MFC dependent on ROL) and another microcosm was equipped with intermittent aeration for evaluating the intermittent aeration dependent cathode reaction (CW-MFC with additional IA). The CW-MFC with additional IA has achieved 78.71% and 53.23%, and CW-MFC dependent on ROL has achieved 72.17% and 46.77% COD removal from synthetic wastewater containing glucose loads of 0.7gL -1 and 2.0gL -1 , respectively. The maximum power density of 31.04mWm -3 and 19.60mWm -3 was achieved in CW-MFC with additional IA and CW-MFC dependent on ROL, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Synthesis and application of polypyrrole/carrageenan nano-bio composite as a cathode catalyst in microbial fuel cells.

    PubMed

    Esmaeili, Chakavak; Ghasemi, Mostafa; Heng, Lee Yook; Hassan, Sedky H A; Abdi, Mahnaz M; Daud, Wan Ramli Wan; Ilbeygi, Hamid; Ismail, Ahmad Fauzi

    2014-12-19

    A novel nano-bio composite polypyrrole (PPy)/kappa-carrageenan(KC) was fabricated and characterized for application as a cathode catalyst in a microbial fuel cell (MFC). High resolution SEM and TEM verified the bud-like shape and uniform distribution of the PPy in the KC matrix. X-ray diffraction (XRD) has approved the amorphous structure of the PPy/KC as well. The PPy/KC nano-bio composites were then studied as an electrode material, due to their oxygen reduction reaction (ORR) ability as the cathode catalyst in the MFC and the results were compared with platinum (Pt) as the most common cathode catalyst. The produced power density of the PPy/KC was 72.1 mW/m(2) while it was 46.8 mW/m(2) and 28.8 mW/m(2) for KC and PPy individually. The efficiency of the PPy/KC electrode system is slightly lower than a Pt electrode (79.9 mW/m(2)) but due to the high cost of Pt electrodes, the PPy/KC electrode system has potential to be an alternative electrode system for MFCs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Cubic PdNP-based air-breathing cathodes integrated in glucose hybrid biofuel cells

    NASA Astrophysics Data System (ADS)

    Faggion Junior, D.; Haddad, R.; Giroud, F.; Holzinger, M.; Maduro de Campos, C. E.; Acuña, J. J. S.; Domingos, J. B.; Cosnier, S.

    2016-05-01

    Cubic Pd nanoparticles (PdNPs) were synthesized using ascorbic acid as a reducing agent and were evaluated for the catalytic oxygen reduction reaction. PdNPs were confined with multiwalled carbon nanotube (MWCNT) dispersions to form black suspensions and these inks were dropcast onto glassy carbon electrodes. Different nanoparticle sizes were synthesized and investigated upon oxygen reduction capacities (onset potential and electrocatalytic current densities) under O2 saturated conditions at varying pH values. Strong evidence of O2 diffusion limitation was demonstrated. In order to overcome oxygen concentration and diffusion limitations in solution, we used a gas diffusion layer to create a PdNP-based air-breathing cathode, which delivered -1.5 mA cm-2 at 0.0 V with an onset potential of 0.4 V. This air-breathing cathode was combined with a specially designed phenanthrolinequinone/glucose dehydrogenase-based anode to form a complete glucose/O2 hybrid bio-fuel cell providing an open circuit voltage of 0.554 V and delivering a maximal power output of 184 +/- 21 μW cm-2 at 0.19 V and pH 7.0.Cubic Pd nanoparticles (PdNPs) were synthesized using ascorbic acid as a reducing agent and were evaluated for the catalytic oxygen reduction reaction. PdNPs were confined with multiwalled carbon nanotube (MWCNT) dispersions to form black suspensions and these inks were dropcast onto glassy carbon electrodes. Different nanoparticle sizes were synthesized and investigated upon oxygen reduction capacities (onset potential and electrocatalytic current densities) under O2 saturated conditions at varying pH values. Strong evidence of O2 diffusion limitation was demonstrated. In order to overcome oxygen concentration and diffusion limitations in solution, we used a gas diffusion layer to create a PdNP-based air-breathing cathode, which delivered -1.5 mA cm-2 at 0.0 V with an onset potential of 0.4 V. This air-breathing cathode was combined with a specially designed phenanthrolinequinone

  14. Microbial contamination level of air in animal waste utilization plants.

    PubMed

    Chmielowiec-Korzeniowska, Anna; Tymczyna, Leszek; Drabik, Agata; Krzosek, Łukasz

    2016-01-01

    The aim of this research was evaluation of microbial contamination of air within and in the vicinity of animal waste disposal plants. Air samples were analyzed to determine total bacterial and fungal counts as well as microbial species composition. Measurements of climate conditions (temperature, humidity, air motion) and total dust concentration were also performed. Total numbers of bacteria and fungi surpassed the threshold limit values for production halls. The most abundant bacteria detected were those consisting of physiological microflora of animal dermis and mucosa. Fungal species composition proved to be most differentiated in the air beyond the plant area. Aspergillus versicolor, a pathogenic and allergenic filamentous fungus, was isolated only inside the rendering plant processing hall. The measurement results showed a low sanitary-hygienic state of air in the plant processing halls and substantial air pollution in its immediate vicinity.

  15. Cathodic reduction of hexavalent chromium [Cr(VI)] coupled with electricity generation in microbial fuel cells.

    PubMed

    Wang, Gang; Huang, Liping; Zhang, Yifeng

    2008-11-01

    A novel approach to Cr(VI)-contaminated wastewater treatment was investigated using microbial fuel cell technologies in fed-batch mode. By using synthetic Cr(VI)-containing wastewater as catholyte and anaerobic microorganisms as anodic biocatalyst, Cr(VI) at 100 mg/l was completely removed during 150 h (initial pH 2). The maximum power density of 150 mW/m(2) (0.04 mA/cm(2)) and the maximum open circuit voltage of 0.91 V were generated with Cr(VI) at 200 mg/l as electron acceptor. This work verifies the possibility of simultaneous electricity production and cathodic Cr(VI) reduction.

  16. Impact of Ferrous Iron on Microbial Community of the Biofilm in Microbial Fuel Cells.

    PubMed

    Liu, Qian; Liu, Bingfeng; Li, Wei; Zhao, Xin; Zuo, Wenjing; Xing, Defeng

    2017-01-01

    The performance of microbial electrochemical cells depends upon microbial community structure and metabolic activity of the electrode biofilms. Iron as a signal affects biofilm development and enrichment of exoelectrogenic bacteria. In this study, the effect of ferrous iron on microbial communities of the electrode biofilms in microbial fuel cells (MFCs) was investigated. Voltage production showed that ferrous iron of 100 μM facilitated MFC start-up compared to 150 μM, 200 μM, and without supplement of ferrous iron. However, higher concentration of ferrous iron had an inhibitive influence on current generation after 30 days of operation. Illumina Hiseq sequencing of 16S rRNA gene amplicons indicated that ferrous iron substantially changed microbial community structures of both anode and cathode biofilms. Principal component analysis showed that the response of microbial communities of the anode biofilms to higher concentration of ferrous iron was more sensitive. The majority of predominant populations of the anode biofilms in MFCs belonged to Geobacter , which was different from the populations of the cathode biofilms. An obvious shift of community structures of the cathode biofilms occurred after ferrous iron addition. This study implied that ferrous iron influenced the power output and microbial community of MFCs.

  17. Carbonate species as OH- carriers for decreasing the pH gradient between cathode and anode in biological fuel cells.

    PubMed

    Torres, César I; Lee, Hyung-Sool; Rittmann, Bruce E

    2008-12-01

    Anodes of biological fuel cells (BFCs) normally must operate at a near-neutral pH in the presence of various ionic species required for the function of the biological catalyst (e.g., substrate, nutrients, and buffers). These ionic species are in higher concentration than protons (H+) and hydroxides (OH-); slow transport of H+ and OH- equivalents between anode and cathode compartments can lead to a large pH gradient that can inhibit the function of biological components, decrease voltage efficiency in BFCs, or both. We evaluate the use of carbonate species as OH- carriers from the cathode to the anode compartment. This is achieved by adding CO2 to the influent air in the cathode. CO2 is an acid that combines with OH- in the cathode to produce bicarbonate and carbonate. These species can migrate to the anode compartment as OH- carriers at a rate much greater than can OH- itself when the pH is not extremely high in the cathode compartment We demonstrate this concept by feeding different air/CO2 mixtures to the cathode of a dual-chamber microbial fuel cell (MFC) fed with acetate as substrate. Our results show a 45% increase in power density (from 1.9 to 2.8 W/m2) by feeding air augmented with 2-10% CO2. The cell voltage increased by as much as 120 mV, indicating that the pH gradient decreased by as much as 2 pH units. Analysis of the anode effluent showed an average increase of 4.9 mM in total carbonate, indicating that mostly carbonate was transferred from the cathode compartment This process provides a simple way to minimize potential losses in BFCs due to pH gradients between anode and cathode compartments.

  18. [Microbial air monitoring in operating theatre: active and passive samplings].

    PubMed

    Pasquarella, C; Masia, M D; Nnanga, Nga; Sansebastiano, G E; Savino, A; Signorelli, C; Veronesi, L

    2004-01-01

    Microbial air contamination was evaluated in 11 operating theatres using active and passive samplings. SAS (Surface Air System) air sampling was used to evaluate cfu/m3 and settle plates were used to measure the index of microbial air contamination (IMA). Samplings were performed at the same time on three different days, at three different times (before, during and after the surgical activity). Two points were monitored (patient area and perimeter of the operating theatre). Moreover, the cfu/m3 were evaluated at the air inlet of the conditioner system. 74.7% of samplings performed at the air inlet and 66.7% of the samplings performed at the patient area before the beginning of the surgical activity (at rest) exceeded the 35 cfu/m3 used as threshold value. 100% of IMA values exceeded the threshold value of 5. Using both active and passive sampling, the microbial contamination was shown to increase significantly during activity. The cfu values were higher at the patient area than at the perimeter of the operating theatre. Mean values of the cfu/m3 during activity at the patient area ranged from a minimum of 61+/-41 cfu/m3 to a maximum of 242+/-136 cfu/m3; IMA values ranged from a minimum of 19+/-10 to a maximum of 129+/-60. 15.2% of samplings performed at the patient area using SAS and 75.8% of samplings performed using settle plates exceeded the threshold values of 180 cfu/m3 and 25 respectively, with a significant difference of the percentages. The highest values were found in the operating theatre with inadequate structural and managerial conditions. These findings confirm that the microbiological quality of air may be considered a mirror of the hygienic conditions of the operating theatre. Settle plates proved to be more sensitive in detecting the increase of microbial air contamination related to conditions that could compromise the quality of the air in operating theatres.

  19. Graphene oxide electrocatalyst on MnO2 air cathode as an efficient electron pump for enhanced oxygen reduction in alkaline solution

    NASA Astrophysics Data System (ADS)

    Basirun, Wan Jeffrey; Sookhakian, Mehran; Baradaran, Saeid; Endut, Zulkarnain; Mahmoudian, Mohammad Reza; Ebadi, Mehdi; Yousefi, Ramin; Ghadimi, Hanieh; Ahmed, Sohail

    2015-03-01

    Graphene oxide (GO) was deposited on the surface of a MnO2 air cathode by thermal evaporation at 50°C from a GO colloidal suspension. Fourier transformed infrared spectroscopy and field emission scanning electron microscopy confirmed the presence of GO on the MnO2 air cathode (GO-MnO2). Voltammetry and chrono-amperometry showed increased currents for the oxygen reduction reaction (ORR) in 6 M KOH solution for GO-MnO2 compared to the MnO2 cathode. The GO-MnO2 was used as an air cathode in an alkaline tin-air cell and produced a maximum power density of 13 mW cm-2, in contrast to MnO2, which produced a maximum power density of 9.2 mW cm-2. The electrochemical impedance spectroscopy results suggest that the chemical step for the ORR is the rate determining step, as proposed earlier by different researchers. It is suggested that the presence of GO and electrochemically reduced graphene oxide (ERGO) on the MnO2 surface are responsible for the increased rate of this step, whereby GO and ERGO accelerate the process of electron donation to the MnO2 and to adsorbed oxygen atoms.

  20. Microbial fuel cells

    DOEpatents

    Nealson, Kenneth H; Pirbazari, Massoud; Hsu, Lewis

    2013-04-09

    A microbial fuel cell includes an anode compartment with an anode and an anode biocatalyst and a cathode compartment with a cathode and a cathode biocatalyst, with a membrane positioned between the anode compartment and the cathode compartment, and an electrical pathway between the anode and the cathode. The anode biocatalyst is capable of catalyzing oxidation of an organic substance, and the cathode biocatalyst is capable of catalyzing reduction of an inorganic substance. The reduced organic substance can form a precipitate, thereby removing the inorganic substance from solution. In some cases, the anode biocatalyst is capable of catalyzing oxidation of an inorganic substance, and the cathode biocatalyst is capable of catalyzing reduction of an organic or inorganic substance.

  1. Fibrous polyaniline@manganese oxide nanocomposites as supercapacitor electrode materials and cathode catalysts for improved power production in microbial fuel cells.

    PubMed

    Ansari, Sajid Ali; Parveen, Nazish; Han, Thi Hiep; Ansari, Mohammad Omaish; Cho, Moo Hwan

    2016-04-07

    Fibrous Pani-MnO2 nanocomposite were prepared using a one-step and scalable in situ chemical oxidative polymerization method. The formation, structural and morphological properties were investigated using a range of characterization techniques. The electrochemical capacitive behavior of the fibrous Pani-MnO2 nanocomposite was examined by cyclic voltammetry and galvanostatic charge-discharge measurements using a three-electrode experimental setup in an aqueous electrolyte. The fibrous Pani-MnO2 nanocomposite achieved high capacitance (525 F g(-1) at a current density of 2 A g(-1)) and excellent cycling stability of 76.9% after 1000 cycles at 10 A g(-1). Furthermore, the microbial fuel cell constructed with the fibrous Pani-MnO2 cathode catalyst showed an improved power density of 0.0588 W m(-2), which was higher than that of pure Pani and carbon paper, respectively. The improved electrochemical supercapacitive performance and cathode catalyst performance in microbial fuel cells were attributed mainly to the synergistic effect of Pani and MnO2 in fibrous Pani-MnO2, which provides high surface area for the electrode/electrolyte contact as well as electronic conductive channels and exhibits pseudocapacitance behavior.

  2. Highly ordered and ultra-long carbon nanotube arrays as air cathodes for high-energy-efficiency Li-oxygen batteries

    NASA Astrophysics Data System (ADS)

    Yu, Ruimin; Fan, Wugang; Guo, Xiangxin; Dong, Shaoming

    2016-02-01

    Carbonaceous air cathodes with rational architecture are vital for the nonaqueous Li-O2 batteries to achieve large energy density, high energy efficiency and long cycle life. In this work, we report the cathodes made of highly ordered and vertically aligned carbon nanotubes grown on permeable Ta foil substrates (VACNTs-Ta) via thermal chemical vapour deposition. The VACNTs-Ta, composed of uniform carbon nanotubes with approximately 240 μm in superficial height, has the super large surface area. Meanwhile, the oriented carbon nanotubes provide extremely outstanding passageways for Li ions and oxygen species. Electrochemistry tests of VACNTs-Ta air cathodes show enhancement in discharge capacity and cycle life compared to those made from short-range oriented and disordered carbon nanotubes. By further combining with the LiI redox mediator that is dissolved in the tetraethylene dimethyl glycol based electrolytes, the batteries exhibit more than 200 cycles at the current density of 200 mA g-1 with a cut-off discharge capacity of 1000 mAh g-1, and their energy efficiencies increase from 50% to 82%. The results here demonstrate the importance of cathode construction for high-energy-efficiency and long-life Li-O2 batteries.

  3. Evaluation of Cathode Air Flow Transients in a SOFC/GT Hybrid System Using Hardware in the Loop Simulation.

    PubMed

    Zhou, Nana; Yang, Chen; Tucker, David

    2015-02-01

    Thermal management in the fuel cell component of a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system can be improved by effective management and control of the cathode airflow. The disturbances of the cathode airflow were accomplished by diverting air around the fuel cell system through the manipulation of a hot-air bypass valve in open loop experiments, using a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). The dynamic responses of the fuel cell component and hardware component of the hybrid system were studied in this paper.

  4. Response of the microbial community structure of biofilms to ferric iron in microbial fuel cells.

    PubMed

    Liu, Qian; Yang, Yang; Mei, Xiaoxue; Liu, Bingfeng; Chen, Chuan; Xing, Defeng

    2018-08-01

    Ferric iron can affect the current generation of microbial electrochemical system (MES); however, how it influences microbial biofilm formation and metabolic activity has not been reported. Here, we describe the response of microbial electrode biofilm communities to insoluble ferric iron (Fe 3+ ) at different concentrations in microbial fuel cells (MFCs). Insoluble ferric iron (200μM) improved electrochemical activity of the MFCs microbial biofilms during start-up and resulted in a higher maximum power density of 0.95W/m 2 , compared with the control (0.76W/m 2 ), 500μM Fe 3+ (0.83W/m 2 ), 1000μM Fe 3+ (0.73W/m 2 ), and 2000μM Fe 3+ (0.59W/m 2 ) treatments. Illumina Hiseq sequencing of 16S rRNA gene amplicons indicated that the predominant populations in the anode biofilms of the MFCs belonged to Geobacter, with relative abundance of 66-75%. Microbial cathode biofilm communities were more susceptible to Fe 3+ , as an obvious shift in the cathode biofilm community structures occurred as Fe 3+ concentration was increased. The most predominant populations in the MFC cathode biofilms without Fe 3+ and with 200μM Fe 3+ were affiliated with Thauera (46% and 35%), whereas no absolutely predominant populations were present in the MFC cathode biofilm with 1000μM Fe 3+ . The results demonstrate that a low concentration of Fe 3+ facilitated the power output of MFCs and shaped community structures of the electrode biofilm. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Simultaneous selection of soil electroactive bacterial communities associated to anode and cathode in a two-chamber Microbial Fuel Cell

    NASA Astrophysics Data System (ADS)

    Chiellini, Carolina; Bacci, Giovanni; Fani, Renato; Mocali, Stefano

    2016-04-01

    Different bacteria have evolved strategies to transfer electrons over their cell surface to (or from) their extracellular environment. This electron transfer enables the use of these bacteria in bioelectrochemical systems (BES) such as Microbial Fuel Cells (MFCs). In MFC research the biological reactions at the cathode have long been a secondary point of interest. However, bacterial biocathodes in MFCs represent a potential advantage compared to traditional cathodes, for both their low costs and their low impact on the environment. The main challenge in biocathode set-up is represented by the selection of a bacterial community able to efficiently accept electrons from the electrode, starting from an environmental matrix. In this work, a constant voltage was supplied on a two-chamber MFC filled up with soil over three weeks in order to simultaneously select an electron donor bacterial biomass on the anode and an electron acceptor biomass on the cathode, starting from the same soil. Next Generation Sequencing (NGS) analysis was performed to characterize the bacterial community of the initial soil, in the anode, in the cathode and in the control chamber not supplied with any voltage. Results highlighted that both the MFC conditions and the voltage supply affected the soil bacterial communities, providing a selection of different bacterial groups preferentially associated to the anode (Betaproteobacteria, Bacilli and Clostridia) and to the cathode (Actinobacteria and Alphaproteobacteria). These results confirmed that several electroactive bacteria are naturally present within a top soil and, moreover, different soil bacterial genera could provide different electrical properties.

  6. Electronic modification of Pt via Ti and Se as tolerant cathodes in air-breathing methanol microfluidic fuel cells.

    PubMed

    Ma, Jiwei; Habrioux, Aurélien; Morais, Cláudia; Alonso-Vante, Nicolas

    2014-07-21

    We reported herein on the use of tolerant cathode catalysts such as carbon supported Pt(x)Ti(y) and/or Pt(x)Se(y) nanomaterials in an air-breathing methanol microfluidic fuel cell. In order to show the improvement of mixed-reactant fuel cell (MRFC) performances obtained with the developed tolerant catalysts, a classical Pt/C nanomaterial was used for comparison. Using 5 M methanol concentration in a situation where the fuel crossover is 100% (MRFC-mixed reactant fuel cell application), the maximum power density of the fuel cell with a Pt/C cathodic catalyst decreased by 80% in comparison with what is observed in the laminar flow fuel cell (LFFC) configuration. With Pt(x)Ti(y)/C and Pt(x)Se(y)/C cathode nanomaterials, the performance loss was only 55% and 20%, respectively. The evaluation of the tolerant cathode catalysts in an air-breathing microfluidic fuel cell suggests the development of a novel nanometric system that will not be size restricted. These interesting results are the consequence of the high methanol tolerance of these advanced electrocatalysts via surface electronic modification of Pt. Herein we used X-ray photoelectron and in situ FTIR spectroscopies to investigate the origin of the high methanol tolerance on modified Pt catalysts.

  7. Experimental study on copper cathode erosion rate and rotational velocity of magnetically driven arcs in a well-type cathode non-transferred plasma torch operating in air

    NASA Astrophysics Data System (ADS)

    Chau, S. W.; Hsu, K. L.; Lin, D. L.; Tzeng, C. C.

    2007-04-01

    The cathode erosion rate, arc root velocity and output power of a well-type cathode (WTC), non-transferred plasma torch operating in air are studied experimentally in this paper. An external solenoid to generate a magnetically driven arc and a circular swirler to produce a vortex flow structure are equipped in the studied torch system, which is designed to reduce the erosion rate at the cathode. A least square technique is applied to correlate the system parameters, i.e. current, axial magnetic field and mass flow rate, with the cathode erosion rate, arc root velocity and system power output. In the studied WTC torch system, the cathode erosion has a major thermal erosion component and a minor component due to the ion-bombardment effect. The cathode erosion increases with the increase of current due to the enhancement in both Joule heating and ion bombardment. The axial magnetic field can significantly reduce the cathode erosion by reducing the thermal loading of cathode materials at the arc root and improving the heat transfer to gas near the cathode. But, the rise in the mass flow rate leads to the deterioration of erosion, since the ion-bombardment effect prevails over the convective cooling at the cathode. The most dominant system parameter to influence the arc root velocity is the axial magnetic field, which is mainly contributed to the magnetic force driving the arc. The growth in current has a negative impact on increasing the arc root velocity, because the friction force acting at the spot due to a severe molten condition becomes the dominant component counteracting the magnetic force. The mass flow rate also suppresses the arc root velocity, as a result of which the arc root moves in the direction against that of the swirled working gas. All system parameters such as current, magnetic field and gas flow rate increase with the increase in the torch output power. The experimental evidences suggest that the axial magnetic field is the most important parameter

  8. Persistent Hydrogen Production by the Photo-Assisted Microbial Electrolysis Cell Using a p-Type Polyaniline Nanofiber Cathode.

    PubMed

    Jeon, Yongwon; Kim, Sunghyun

    2016-12-08

    A microbial electrolysis cell, though considered as a promising, environmentally friendly technology for hydrogen production, suffers from concomitant production of methane. The high hydrogen/methane ratio at the initial operation stage decreases with time. Here we report for the first time the photoassisted microbial electrolysis cell (MEC) for persistent hydrogen production using polyaniline nanofibers as a cathode. Under 0.8 V external bias and laboratory fluorescent light illumination in a single-chamber MEC, continuous hydrogen production from acetate at a rate of 1.78 mH2 3  m -3  d -1 with 79.2 % overall hydrogen recovery was achieved with negligible methane formation for six months. Energy efficiencies based on input electricity as well as input electricity plus substrate were 182 and 66.2 %, respectively. This was attributed to the p-type-semiconductor characteristics of polyaniline nanofibers in which photoexcited electrons are used to reduce protons at the surface and holes are reduced with electrons originating from acetate oxidation at the anode. This method can be extended to microbial wastewater treatment for hydrogen production. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Assisting cultivation of photosynthetic microorganisms by microbial fuel cells to enhance nutrients recovery from wastewater.

    PubMed

    Colombo, Alessandra; Marzorati, Stefania; Lucchini, Giorgio; Cristiani, Pierangela; Pant, Deepak; Schievano, Andrea

    2017-08-01

    Spirulina was cultivated in cathodic compartments of photo-microbial fuel cells (P-MFC). Anodic compartments were fed with swine-farming wastewater, enriched with sodium acetate (2.34g COD L -1 ). Photosynthetic oxygen generation rates were sufficient to sustain cathodic oxygen reduction, significantly improving P-MFC electrochemical performances, as compared to water-cathode control experiments. Power densities (0.8-1Wm -2 ) approached those of air-cathode MFCs, run as control. COD was efficiently removed and only negligible fractions leaked to the cathodic chamber. Spirulina growth rates were comparable to those of control (MFC-free) cultures, while pH was significantly (0.5-1unit) higher in P-MFCs, due to cathodic reactions. Alkaliphilic photosynthetic microorganisms like Spirulina might take advantage of these selective conditions. Electro-migration along with diffusion to the cathodic compartment concurred for the recovery of most nutrients. Only P and Mg were retained in the anodic chamber. A deeper look into electro-osmotic mechanisms should be addressed in future studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Contribution of Vegetation to the Microbial Composition of Nearby Outdoor Air

    PubMed Central

    Adams, Rachel I.

    2016-01-01

    ABSTRACT Given that epiphytic microbes are often found in large population sizes on plants, we tested the hypothesis that plants are quantitatively important local sources of airborne microorganisms. The abundance of microbial communities, determined by quantifying bacterial 16S RNA genes and the fungal internal transcribed spacer (ITS) region, in air collected directly above vegetation was 2- to 10-fold higher than that in air collected simultaneously in an adjacent nonvegetated area 50 m upwind. Nonmetric multidimensional scaling revealed that the composition of airborne bacteria in upwind air samples grouped separately from that of downwind air samples, while communities on plants and downwind air could not be distinguished. In contrast, fungal taxa in air samples were more similar to each other than to the fungal epiphytes. A source-tracking algorithm revealed that up to 50% of airborne bacteria in downwind air samples were presumably of local plant origin. The difference in the proportional abundances of a given operational taxonomic unit (OTU) between downwind and upwind air when regressed against the proportional representation of this OTU on the plant yielded a positive slope for both bacteria and fungi, indicating that those taxa that were most abundant on plants proportionally contributed more to downwind air. Epiphytic fungi were less of a determinant of the microbiological distinctiveness of downwind air and upwind air than epiphytic bacteria. Emigration of epiphytic bacteria and, to a lesser extent, fungi, from plants can thus influence the microbial composition of nearby air, a finding that has important implications for surrounding ecosystems, including the built environment into which outdoor air can penetrate. IMPORTANCE This paper addresses the poorly understood role of bacterial and fungal epiphytes, the inhabitants of the aboveground plant parts, in the composition of airborne microbes in outdoor air. It is widely held that epiphytes contribute

  11. Contribution of Vegetation to the Microbial Composition of Nearby Outdoor Air.

    PubMed

    Lymperopoulou, Despoina S; Adams, Rachel I; Lindow, Steven E

    2016-07-01

    Given that epiphytic microbes are often found in large population sizes on plants, we tested the hypothesis that plants are quantitatively important local sources of airborne microorganisms. The abundance of microbial communities, determined by quantifying bacterial 16S RNA genes and the fungal internal transcribed spacer (ITS) region, in air collected directly above vegetation was 2- to 10-fold higher than that in air collected simultaneously in an adjacent nonvegetated area 50 m upwind. Nonmetric multidimensional scaling revealed that the composition of airborne bacteria in upwind air samples grouped separately from that of downwind air samples, while communities on plants and downwind air could not be distinguished. In contrast, fungal taxa in air samples were more similar to each other than to the fungal epiphytes. A source-tracking algorithm revealed that up to 50% of airborne bacteria in downwind air samples were presumably of local plant origin. The difference in the proportional abundances of a given operational taxonomic unit (OTU) between downwind and upwind air when regressed against the proportional representation of this OTU on the plant yielded a positive slope for both bacteria and fungi, indicating that those taxa that were most abundant on plants proportionally contributed more to downwind air. Epiphytic fungi were less of a determinant of the microbiological distinctiveness of downwind air and upwind air than epiphytic bacteria. Emigration of epiphytic bacteria and, to a lesser extent, fungi, from plants can thus influence the microbial composition of nearby air, a finding that has important implications for surrounding ecosystems, including the built environment into which outdoor air can penetrate. This paper addresses the poorly understood role of bacterial and fungal epiphytes, the inhabitants of the aboveground plant parts, in the composition of airborne microbes in outdoor air. It is widely held that epiphytes contribute to atmospheric

  12. Active water management at the cathode of a planar air-breathing polymer electrolyte membrane fuel cell using an electroosmotic pump

    NASA Astrophysics Data System (ADS)

    Fabian, T.; O'Hayre, R.; Litster, S.; Prinz, F. B.; Santiago, J. G.

    In a typical air-breathing fuel cell design, ambient air is supplied to the cathode by natural convection and dry hydrogen is supplied to a dead-ended anode. While this design is simple and attractive for portable low-power applications, the difficulty in implementing effective and robust water management presents disadvantages. In particular, excessive flooding of the open-cathode during long-term operation can lead to a dramatic reduction of fuel cell power. To overcome this limitation, we report here on a novel air-breathing fuel cell water management design based on a hydrophilic and electrically conductive wick in conjunction with an electroosmotic (EO) pump that actively pumps water out of the wick. Transient experiments demonstrate the ability of the EO-pump to "resuscitate" the fuel cell from catastrophic flooding events, while longer term galvanostatic measurements suggest that the design can completely eliminate cathode flooding using less than 2% of fuel cell power, and lead to stable operation with higher net power performance than a control design without EO-pump. This demonstrates that active EO-pump water management, which has previously only been demonstrated in forced-convection fuel cell systems, can also be applied effectively to miniaturized (<5 W) air-breathing fuel cell systems.

  13. Microbial Risk Assessment of Air Conditioning Condensate Reuse

    EPA Science Inventory

    Air conditioning condensate can provide a substantial water source for building-scale collection and non-potable use. Although produced water is anticipated to be of generally high quality, the potential for microbial contamination by biofilm-associated opportunistic pathogens t...

  14. Selective cathodic microbial biofilm retention allows a high current-to-sulfide efficiency in sulfate-reducing microbial electrolysis cells.

    PubMed

    Pozo, Guillermo; Lu, Yang; Pongy, Sebastien; Keller, Jürg; Ledezma, Pablo; Freguia, Stefano

    2017-12-01

    Selective microbial retention is of paramount importance for the long-term performance of cathodic sulfate reduction in microbial electrolysis cells (MECs) due to the slow growth rate of autotrophic sulfate-reducing bacteria. In this work, we investigate the biofilm retention and current-to-sulfide conversion efficiency using carbon granules (CG) or multi-wall carbon nanotubes deposited on reticulated vitreous carbon (MWCNT-RVC) as electrode materials. For ~2months, the MECs were operated at sulfate loading rates of 21 to 309gSO 4 -S/m 2 /d. Although MWCNT-RVC achieved a current density of 57±11A/m 2 , greater than the 32±9A/m 2 observed using CG, both materials exhibited similar sulfate reduction rates (SRR), with MWCNT-RVC reaching 104±16gSO 4 -S/m 2 /d while 110±13gSO 4 -S/m 2 /d were achieved with CG. Pyrosequencing analysis of the 16S rRNA at the end of experimentation revealed a core community dominated by Desulfovibrio (28%), Methanobacterium (19%) and Desulfomicrobium (14%), on the MWCNT-RVC electrodes. While a similar Desulfovibrio relative abundance of 29% was found in CG-biofilms, Desulfomicrobium was found to be significantly less abundant (4%) and Methanobacterium practically absent (0.2%) on CG electrodes. Surprisingly, our results show that CG can achieve higher current-to-sulfide efficiencies at lower power consumption than the nano-modified three-dimensional MWCNT-RVC. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Free-Standing Air Cathodes Based on 3D Hierarchically Porous Carbon Membranes: Kinetic Overpotential of Continuous Macropores in Li-O2 Batteries.

    PubMed

    Xu, Shu-Mao; Liang, Xiao; Ren, Zhi-Chu; Wang, Kai-Xue; Chen, Jie-Sheng

    2018-06-04

    Free-standing macroporous air electrodes with enhanced interfacial contact, rapid mass transport, and tailored deposition space for large amounts of Li 2 O 2 are essential for improving the rate performance of Li-O 2 batteries. An ordered mesoporous carbon membrane with continuous macroporous channels was prepared by inversely topological transformation from ZnO nanorod array. Utilized as a free-standing air cathode for Li-O 2 battery, the hierarchically porous carbon membrane shows superior rate performance. However, the increased cross-sectional area of the continuous macropores on the cathode surface leads to a kinetic overpotential with large voltage hysteresis and linear voltage variation against Butler-Volmer behavior. The kinetics were investigated based on the rate-determining step of second electron transfer accompanied by migration of Li + in solid or quasi-solid intermediates. These discoveries shed light on the design of the air cathode for Li-O 2 batteries with high-rate performance. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Combinatorial high-throughput optical screening of high performance Pd alloy cathode for hybrid Li-air battery.

    PubMed

    Jun, Young Jin; Park, Sung Hyeon; Woo, Seong Ihl

    2014-12-08

    Combinatorial high-throughput optical screening method was developed to find the optimum composition of highly active Pd-based catalysts at the cathode of the hybrid Li-air battery. Pd alone, which is one-third the cost of Pt, has difficulty in replacing Pt; therefore, the integration of other metals was investigated to improve its performance toward oxygen reduction reaction (ORR). Among the binary Pd-based catalysts, the composition of Pd-Ir derived catalysts had higher performance toward ORR compared to other Pd-based binary combinations. The composition at 88:12 at. % (Pd: Ir) showed the highest activity toward ORR at the cathode of the hybrid Li-air battery. The prepared Pd(88)Ir(12)/C catalyst showed a current density of -2.58 mA cm(-2) at 0.8 V (vs RHE), which was around 30% higher compared to that of Pd/C (-1.97 mA cm(-2)). When the prepared Pd(88)Ir(12)/C catalyst was applied to the hybrid Li-air battery, the polarization of the cell was reduced and the energy efficiency of the cell was about 30% higher than that of the cell with Pd/C.

  17. Metagenome-Assembled Genome Sequences of Acetobacterium sp. Strain MES1 and Desulfovibrio sp. Strain MES5 from a Cathode-Associated Acetogenic Microbial Community.

    PubMed

    Ross, Daniel E; Marshall, Christopher W; May, Harold D; Norman, R Sean

    2017-09-07

    Draft genome sequences of Acetobacterium sp. strain MES1 and Desulfovibrio sp. strain MES5 were obtained from the metagenome of a cathode-associated community enriched within a microbial electrosynthesis system (MES). The draft genome sequences provide insight into the functional potential of these microorganisms within an MES and a foundation for future comparative analyses. Copyright © 2017 Ross et al.

  18. Salinity-gradient energy driven microbial electrosynthesis of hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Li, Xiaohu; Angelidaki, Irini; Zhang, Yifeng

    2017-02-01

    Hydrogen peroxide (H2O2) as a strong oxidant, is widely used in various chemical industries and environmental remediation processes. In this study, we developed an innovative method for cost-effective production of H2O2 by using a microbial reverse-electrodialysis electrolysis cell (MREC). In the MREC, electrical potential generated by the exoelectrogens and the salinity-gradient between salt and fresh water were utilized to drive the high-rate H2O2 production. Operational parameters such as air flow rate, pH, cathodic potential, flow rate of salt and fresh water were investigated. The optimal H2O2 production was observed at salt and fresh water flow rate of 0.5 mL min-1, air flow rate of 12-20 mL min-1, cathode potential of -0.485 ± 0.025 V (vs Ag/AgCl). The maximum H2O2 accumulated concentration of 778 ± 11 mg L-1 was obtained at corresponding production rate of 11.5 ± 0.5 mg L-1 h-1. The overall energy input for the synthesis process was 0.45 ± 0.03 kWh kg-1 H2O2. Cathode potential was the key factor for H2O2 production, which was mainly affected by the air flow rate. This work for the first time proved the potential of MREC as an efficient platform technology for simultaneous electrosynthesis of valuable chemicals and utilization of salinity-gradient energy.

  19. Removal and fate of trace organic compounds in microbial fuel cells.

    PubMed

    Wang, Heming; Heil, Dean; Ren, Zhiyong Jason; Xu, Pei

    2015-04-01

    This study focused on understanding and characterizing the removal of trace organic compounds (TOrCs) in microbial fuel cells (MFC). 26 TOrCs with broad physicochemical properties were spiked in synthetic wastewater. Single-chamber air-cathode MFC (SMFC) and double-chamber air-cathode MFC (DMFC) were constructed to provide combined or separated oxidation/reduction environments for TOrCs removal. The study showed that TOrCs removal processes involved both sorption and biodegradation. For neutral TOrCs, the removal efficiency was affected primarily by the biodegradability probability and hydrophobicity of the compounds, while electrostatic interactions played an additional role in the MFCs as the removal of positively charged TOrCs was generally higher than negatively charged TOrCs. The presence of TOrCs showed negligible impact on MFC power generation, likewise the operation of MFCs had marginal effect on TOrCs removal, except longer residence time in MFCs improved biological removal performance. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Removal of copper from aqueous solution by electrodeposition in cathode chamber of microbial fuel cell.

    PubMed

    Tao, Hu-Chun; Liang, Min; Li, Wei; Zhang, Li-Juan; Ni, Jin-Ren; Wu, Wei-Min

    2011-05-15

    Based on energetic analysis, a novel approach for copper electrodeposition via cathodic reduction in microbial fuel cells (MFCs) was proposed for the removal of copper and recovery of copper solids as metal copper and/or Cu(2)O in a cathode with simultaneous electricity generation with organic matter. This was examined by using dual-chamber MFCs (chamber volume, 1L) with different concentrations of CuSO(4) solution (50.3 ± 5.8, 183.3 ± 0.4, 482.4 ± 9.6, 1007.9 ± 52.0 and 6412.5 ± 26.7 mg Cu(2+)/L) as catholyte at pH 4.7, and different resistors (0, 15, 390 and 1000 Ω) as external load. With glucose as a substrate and anaerobic sludge as an inoculum, the maximum power density generated was 339 mW/m(3) at an initial 6412.5 ± 26.7 mg Cu(2+)/L concentration. High Cu(2+) removal efficiency (>99%) and final Cu(2+) concentration below the USA EPA maximum contaminant level (MCL) for drinking water (1.3mg/L) was observed at an initial 196.2 ± 0.4 mg Cu(2+)/L concentration with an external resistor of 15 Ω, or without an external resistor. X-ray diffraction analysis confirmed that Cu(2+) was reduced to cuprous oxide (Cu(2)O) and metal copper (Cu) on the cathodes. Non-reduced brochantite precipitates were observed as major copper precipitates in the MFC with a high initial Cu(2+) concentration (0.1M) but not in the others. The sustainability of high Cu(2+) removal (>96%) by MFC was further examined by fed-batch mode for eight cycles. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Carbon-containing cathodes for enhanced electron emission

    DOEpatents

    Cao, Renyu; Pan, Lawrence; Vergara, German; Fox, Ciaran

    2000-01-01

    A cathode has electropositive atoms directly bonded to a carbon-containing substrate. Preferably, the substrate comprises diamond or diamond-like (sp.sup.3) carbon, and the electropositive atoms are Cs. The cathode displays superior efficiency and durability. In one embodiment, the cathode has a negative electron affinity (NEA). The cathode can be used for field emission, thermionic emission, or photoemission. Upon exposure to air or oxygen, the cathode performance can be restored by annealing or other methods. Applications include detectors, electron multipliers, sensors, imaging systems, and displays, particularly flat panel displays.

  2. Factors influencing microbial colonies in the air of operating rooms.

    PubMed

    Fu Shaw, Ling; Chen, Ian Horng; Chen, Chii Shya; Wu, Hui Hsin; Lai, Li Shing; Chen, Yin Yin; Wang, Fu Der

    2018-01-02

    The operating room (OR) of the hospital is a special unit that requires a relatively clean environment. The microbial concentration of an indoor OR extrinsically influences surgical site infection rates. The aim of this study was to use active sampling methods to assess microbial colony counts in working ORs and to determine the factors affecting air contamination in a tertiary referral medical center. This study was conducted in 28 operating rooms located in a 3000-bed medical center in northern Taiwan. The microbiologic air counts were measured using an impactor air sampler from May to August 2015. Information about the procedure-related operative characteristics and surgical environment (environmental- and personnel-related factors) characteristics was collected. A total of 250 air samples were collected during surgical procedures. The overall mean number of bacterial colonies in the ORs was 78 ± 47 cfu/m 3 . The mean number of colonies was the highest for transplant surgery (123 ± 60 cfu/m 3 ), followed by pediatric surgery (115 ± 30.3 cfu/m 3 ). A total of 25 samples (10%) contained pathogens; Coagulase-negative staphylococcus (n = 12, 4.8%) was the most common pathogen. After controlling for potentially confounding factors by a multiple regression analysis, the surgical stage had the significantly highest correlation with bacterial counts (r = 0.346, p < 0.001). Otherwise, independent factors influencing bacterial counts were the type of surgery (29.85 cfu/m 3 , 95% CI 1.28-58.42, p = 0.041), site of procedure (20.19 cfu/m 3 , 95% CI 8.24-32.14, p = 0.001), number of indoor staff (4.93 cfu/m 3 , 95% CI 1.47-8.38, p = 0.005), surgical staging (36.5 cfu/m 3 , 95% CI 24.76-48.25, p < 0.001), and indoor air temperature (9.4 cfu/m 3 , 95% CI 1.61-17.18, p = 0.018). Under the well-controlled ventilation system, the mean microbial colony counts obtained by active sampling in different working ORs were low. The

  3. Portable Cathode-Air Vapor-Feed Electrochemical Medical Oxygen Concentrator (OC)

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Ashwin

    2015-01-01

    Missions on the International Space Station and future space exploration will present significant challenges to crew health care capabilities, particularly in the efficient utilization of onboard oxygen resources. Exploration vehicles will require lightweight, compact, and portable oxygen concentrators that can provide medical-grade oxygen from the ambient cabin air. Current pressure-swing adsorption OCs are heavy and bulky, require significant start-up periods, operate in narrow temperature ranges, and require a liquid water feed. Lynntech, Inc., has developed an electrochemical OC that operates with a cathode-air vapor feed, eliminating the need for a bulky onboard water supply. Lynntech's OC is smaller and lighter than conventional pressure-swing OCs, is capable of instant start-up, and operates over a temperature range of 5-80 C. Accomplished through a unique nanocomposite proton exchange membrane and catalyst technology, the unit delivers 4 standard liters per minute of humidified oxygen at 60 percent concentration. The technology enables both ambient-pressure operating devices for portable applications and pressurized (up to 3,600 psi) OC devices for stationary applications.

  4. Designing Air-Stable O 3-Type Cathode Materials by Combined Structure Modulation for Na-Ion Batteries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yao, Hu-Rong; Wang, Peng-Fei; Gong, Yue

    As promising high-capacity cathode materials for Na-ion batteries, O 3-type Na-based metal oxides always suffer from their poor air stability originating from the spontaneous extraction of Na and oxidation of transition metals when exposed to air. Here, a combined structure modulation is proposed to tackle concurrently the two handicaps via reducing Na layers spacing and simultaneously increasing valence state of transition metals. Guided by density functional theory calculations, we demonstrate such a modulation can be subtly realized through cosubstitution of one kind of heteroatom with comparable electronegativity and another one with substantially different Fermi level, by adjusting the structure ofmore » NaNi 0.5Mn 0.5O 2 via Cu/Ti codoping. The as-obtained NaNi 0.45Cu 0.05Mn 0.4Ti 0.1O 2 exhibits an increase of 20 times in stable air-exposure period and 9 times in capacity retention after 500 cycles, and even retains its structure and capacity after being soaked in water. In such a simple and effective structure modulation reveals a new avenue for high-performance O 3-type cathodes and pushes the large-scale industrialization of Na-ion batteries a decisive step forward.« less

  5. Designing Air-Stable O 3-Type Cathode Materials by Combined Structure Modulation for Na-Ion Batteries

    DOE PAGES

    Yao, Hu-Rong; Wang, Peng-Fei; Gong, Yue; ...

    2017-06-09

    As promising high-capacity cathode materials for Na-ion batteries, O 3-type Na-based metal oxides always suffer from their poor air stability originating from the spontaneous extraction of Na and oxidation of transition metals when exposed to air. Here, a combined structure modulation is proposed to tackle concurrently the two handicaps via reducing Na layers spacing and simultaneously increasing valence state of transition metals. Guided by density functional theory calculations, we demonstrate such a modulation can be subtly realized through cosubstitution of one kind of heteroatom with comparable electronegativity and another one with substantially different Fermi level, by adjusting the structure ofmore » NaNi 0.5Mn 0.5O 2 via Cu/Ti codoping. The as-obtained NaNi 0.45Cu 0.05Mn 0.4Ti 0.1O 2 exhibits an increase of 20 times in stable air-exposure period and 9 times in capacity retention after 500 cycles, and even retains its structure and capacity after being soaked in water. In such a simple and effective structure modulation reveals a new avenue for high-performance O 3-type cathodes and pushes the large-scale industrialization of Na-ion batteries a decisive step forward.« less

  6. Dynamics of Cathode-Associated Microbial Communities and Metabolite Profiles in a Glycerol-Fed Bioelectrochemical System

    PubMed Central

    Dennis, Paul G.; Harnisch, Falk; Yeoh, Yun Kit; Tyson, Gene W.

    2013-01-01

    Electrical current can be used to supply reducing power to microbial metabolism. This phenomenon is typically studied in pure cultures with added redox mediators to transfer charge. Here, we investigate the development of a current-fed mixed microbial community fermenting glycerol at the cathode of a bioelectrochemical system in the absence of added mediators and identify correlations between microbial diversity and the respective product outcomes. Within 1 week of inoculation, a Citrobacter population represented 95 to 99% of the community and the metabolite profiles were dominated by 1,3-propanediol and ethanol. Over time, the Citrobacter population decreased in abundance while that of a Pectinatus population and the formation of propionate increased. After 6 weeks, several Clostridium populations and the production of valerate increased, which suggests that chain elongation was being performed. Current supply was stopped after 9 weeks and was associated with a decrease in glycerol degradation and alcohol formation. This decrease was reversed by resuming current supply; however, when hydrogen gas was bubbled through the reactor during open-circuit operation (open-circuit potential) as an alternative source of reducing power, glycerol degradation and metabolite production were unaffected. Cyclic voltammetry revealed that the community appeared to catalyze the hydrogen evolution reaction, leading to a +400-mV shift in its onset potential. Our results clearly demonstrate that current supply can alter fermentation profiles; however, further work is needed to determine the mechanisms behind this effect. In addition, operational conditions must be refined to gain greater control over community composition and metabolic outcomes. PMID:23603684

  7. Electricity generation through a photo sediment microbial fuel cell using algae at the cathode.

    PubMed

    Neethu, B; Ghangrekar, M M

    2017-12-01

    Sediment microbial fuel cells (SMFCs) are bio-electrochemical devices generating electricity from redox gradients occurring across the sediment-water interface. Sediment microbial carbon-capture cell (SMCC), a modified SMFC, uses algae grown in the overlying water of sediment and is considered as a promising system for power generation along with algal cultivation. In this study, the performance of SMCC and SMFC was evaluated in terms of power generation, dissolved oxygen variations, sediment organic matter removal and algal growth. SMCC gave a maximum power density of 22.19 mW/m 2 , which was 3.65 times higher than the SMFC operated under similar conditions. Sediment organic matter removal efficiencies of 77.6 ± 2.1% and 61.0 ± 1.3% were obtained in SMCC and SMFC, respectively. With presence of algae at the cathode, a maximum chemical oxygen demand and total nitrogen removal efficiencies of 63.3 ± 2.3% (8th day) and 81.6 ± 1.2% (10th day), respectively, were observed. The system appears to be favorable from a resources utilization perspective as it does not depend on external aeration or membranes and utilizes algae and organic matter present in sediment for power generation. Thus, SMCC has proven its applicability for installation in an existing oxidation pond for sediment remediation, algae growth, carbon conversion and power generation, simultaneously.

  8. Enhanced microbial electrosynthesis by using defined co-cultures

    PubMed Central

    Deutzmann, Jörg S; Spormann, Alfred M

    2017-01-01

    Microbial uptake of free cathodic electrons presents a poorly understood aspect of microbial physiology. Uptake of cathodic electrons is particularly important in microbial electrosynthesis of sustainable fuel and chemical precursors using only CO2 and electricity as carbon, electron and energy source. Typically, large overpotentials (200 to 400 mV) were reported to be required for cathodic electron uptake during electrosynthesis of, for example, methane and acetate, or low electrosynthesis rates were observed. To address these limitations and to explore conceptual alternatives, we studied defined co-cultures metabolizing cathodic electrons. The Fe(0)-corroding strain IS4 was used to catalyze the electron uptake reaction from the cathode forming molecular hydrogen as intermediate, and Methanococcus maripaludis and Acetobacterium woodii were used as model microorganisms for hydrogenotrophic synthesis of methane and acetate, respectively. The IS4-M. maripaludis co-cultures achieved electromethanogenesis rates of 0.1–0.14 μmol cm−2 h−1 at −400 mV vs standard hydrogen electrode and 0.6–0.9 μmol cm−2 h−1 at −500 mV. Co-cultures of strain IS4 and A. woodii formed acetate at rates of 0.21–0.23 μmol cm−2 h−1 at −400 mV and 0.57–0.74 μmol cm−2 h−1 at −500 mV. These data show that defined co-cultures coupling cathodic electron uptake with synthesis reactions via interspecies hydrogen transfer may lay the foundation for an engineering strategy for microbial electrosynthesis. PMID:27801903

  9. The Denitrification Characteristics and Microbial Community in the Cathode of an MFC with Aerobic Denitrification at High Temperatures.

    PubMed

    Zhao, Jianqiang; Wu, Jinna; Li, Xiaoling; Wang, Sha; Hu, Bo; Ding, Xiaoqian

    2017-01-01

    Microbial fuel cells (MFCs) have attracted much attention due to their ability to generate electricity while treating wastewater. The performance of a double-chamber MFC with simultaneous nitrification and denitrification (SND) in the cathode for treating synthetic high concentration ammonia wastewater was investigated at different dissolved oxygen (DO) concentrations and high temperatures. The results showed that electrode denitrification and traditional heterotrophic denitrification co-existed in the cathode chamber. Electrode denitrification by aerobic denitrification bacterium (ADB) is beneficial for achieving a higher voltage of the MFC at high DO concentrations (3.0-4.2 mg/L), while traditional heterotrophic denitrification is conducive to higher total nitrogen (TN) removal at low DO (0.5-1.0 mg/L) concentrations. Under high DO conditions, the nitrous oxide production and TN removal efficiency were higher with a 50 Ω external resistance than with a 100 Ω resistance, which demonstrated that electrode denitrification by ADB occurred in the cathode of the MFC. Sufficient electrons were inferred to be provided by the electrode to allow ADB survival at low carbon:nitrogen ratios (≤0.3). Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) results showed that increasing the DO resulted in a change of the predominant species from thermophilic autotrophic nitrifiers and facultative heterotrophic denitrifiers at low DO concentrations to thermophilic ADB at high DO concentrations. The predominant phylum changed from Firmicutes to Proteobacteria , and the predominant class changed from Bacilli to Alpha, Beta , and Gamma Proteobacteria .

  10. Methodology for modeling the microbial contamination of air filters.

    PubMed

    Joe, Yun Haeng; Yoon, Ki Young; Hwang, Jungho

    2014-01-01

    In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter.

  11. Methodology for Modeling the Microbial Contamination of Air Filters

    PubMed Central

    Joe, Yun Haeng; Yoon, Ki Young; Hwang, Jungho

    2014-01-01

    In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter. PMID:24523908

  12. PTFE effect on the electrocatalysis of the oxygen reduction reaction in membraneless microbial fuel cells.

    PubMed

    Guerrini, Edoardo; Grattieri, Matteo; Faggianelli, Alessio; Cristiani, Pierangela; Trasatti, Stefano

    2015-12-01

    Influence of PTFE in the external Gas Diffusion Layer (GDL) of open-air cathodes applied to membraneless microbial fuel cells (MFCs) is investigated in this work. Electrochemical measurements on cathodes with different PTFE contents (200%, 100%, 80% and 60%) were carried out to characterize cathodic oxygen reduction reaction, to study the reaction kinetics. It is demonstrated that ORR is not under diffusion-limiting conditions in the tested systems. Based on cyclic voltammetry, an increase of the cathodic electrochemical active area took place with the decrease of PTFE content. This was not directly related to MFC productivity, but to the cathode wettability and the biocathode development. Low electrodic interface resistances (from 1 to 1.5 Ω at the start, to near 0.1 Ω at day 61) indicated a negligible ohmic drop. A decrease of the Tafel slopes from 120 to 80 mV during productive periods of MFCs followed the biological activity in the whole MFC system. A high PTFE content in the cathode showed a detrimental effect on the MFC productivity, acting as an inhibitor of ORR electrocatalysis in the triple contact zone.

  13. Nitrogen, Fluorine, and Boron Ternary Doped Carbon Fibers as Cathode Electrocatalysts for Zinc-Air Batteries.

    PubMed

    Wang, Lei; Wang, Yueqing; Wu, Mingguang; Wei, Zengxi; Cui, Chunyu; Mao, Minglei; Zhang, Jintao; Han, Xiaopeng; Liu, Quanhui; Ma, Jianmin

    2018-05-01

    Zinc-air batteries with high-density energy are promising energy storage devices for the next generation of energy storage technologies. However, the battery performance is highly dependent on the efficiency of oxygen electrocatalyst in the air electrode. Herein, the N, F, and B ternary doped carbon fibers (TD-CFs) are prepared and exhibited higher catalytic properties via the efficient 4e - transfer mechanism for oxygen reduction in comparison with the single nitrogen doped CFs. More importantly, the primary and rechargeable Zn-air batteries using TD-CFs as air-cathode catalysts are constructed. When compared to batteries with Pt/C + RuO 2 and Vulcan XC-72 carbon black catalysts, the TD-CFs catalyzed batteries exhibit remarkable battery reversibility and stability over long charging/discharging cycles. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Novel strategy to mitigate cathode catalyst degradation during air/air startup cycling via the atmospheric resistive switching mechanism of a hydrogen anode with a platinum catalyst supported on tantalum-doped titanium dioxide

    NASA Astrophysics Data System (ADS)

    Shintani, Haruhiko; Kojima, Yuya; Kakinuma, Katsuyoshi; Watanabe, Masahiro; Uchida, Makoto

    2015-10-01

    We propose a new strategy for alleviating the reverse current phenomenon using a unique ;atmospheric resistive switching mechanism; (ARSM) of a metal oxide semiconductor support, such that the electrical resistivity changes depending on the gas atmosphere. The membrane-electrode assembly (MEA) using Ta-doped TiO2-supported platinum (Pt/Ta-TiO2) as the anode catalyst showed approximately one order of magnitude greater resistance in air than in hydrogen. The overpotential of the hydrogen oxidation reaction was negligible up to at least 1.5 A cm-2. The losses of electrochemically active surface area and carbon corrosion of the cathode catalyst during air/air startup cycling were significantly suppressed by the use of the Pt/Ta-TiO2 anode. The decrease in the degradation is attributed to a reduction of the reverse current due to a low oxygen reduction reaction rate at the anode, which showed high resistivity in air. These results demonstrate the effectiveness of the ARSM in mitigating cathode catalyst degradation during air/air startup cycling.

  15. Solar energy powered microbial fuel cell with a reversible bioelectrode.

    PubMed

    Strik, David P B T B; Hamelers, Hubertus V M; Buisman, Cees J N

    2010-01-01

    The solar energy powered microbial fuel cell is an emerging technology for electricity generation via electrochemically active microorganisms fueled by solar energy via in situ photosynthesized metabolites from algae, cyanobacteria, or living higher plants. A general problem with microbial fuel cells is the pH membrane gradient which reduces cell voltage and power output. This problem is caused by acid production at the anode, alkaline production at the cathode, and the nonspecific proton exchange through the membrane. Here we report a solution for a new kind of solar energy powered microbial fuel cell via development of a reversible bioelectrode responsible for both biocatalyzed anodic and cathodic electron transfer. Anodic produced protons were used for the cathodic reduction reaction which held the formation of a pH membrane gradient. The microbial fuel cell continuously generated electricity and repeatedly reversed polarity dependent on aeration or solar energy exposure. Identified organisms within biocatalyzing biofilm of the reversible bioelectrode were algae, (cyano)bacteria and protozoa. These results encourage application of solar energy powered microbial fuel cells.

  16. Electricity generation using white and red wine lees in air cathode microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Pepe Sciarria, Tommy; Merlino, Giuseppe; Scaglia, Barbara; D'Epifanio, Alessandra; Mecheri, Barbara; Borin, Sara; Licoccia, Silvia; Adani, Fabrizio

    2015-01-01

    Microbial fuel cell (MFC) is a useful biotechnology to produce electrical energy from different organic substrates. This work reports for the first time results of the application of single chamber MFCs to generate electrical energy from diluted white wine (WWL) and red wine (RWL) lees. Power obtained was of 8.2 W m-3 (262 mW m-2; 500 Ω) and of 3.1 W m-3 (111 mW m-2; 500Ω) using white and red wine lees, respectively. Biological processes lead to a reduction of chemical oxygen (TCOD) and biological oxygen demand (BOD5) of 27% and 83% for RWL and of 90% and 95% for WWL, respectively. These results depended on the degradability of organic compounds contained, as suggest by BOD5/TCOD of WWL (0.93) vs BOD5/TCOD of RWL (0.33), and to the high presence of polyphenols in RWL that inhibited the process. Coulombic efficiency (CE) of 15 ± 0%, for WWL, was in line with those reported in the literature for other substrates, i.e. CE of 14.9 ± 11.3%. Different substrates led to different microbial consortia, particularly at the anode. Bacterial species responsible for the generation of electricity, were physically connected to the electrode, where the direct electron transfer took place.

  17. Design of experiments and principal component analysis as approaches for enhancing performance of gas-diffusional air-breathing bilirubin oxidase cathode

    NASA Astrophysics Data System (ADS)

    Babanova, Sofia; Artyushkova, Kateryna; Ulyanova, Yevgenia; Singhal, Sameer; Atanassov, Plamen

    2014-01-01

    Two statistical methods, design of experiments (DOE) and principal component analysis (PCA) are employed to investigate and improve performance of air-breathing gas-diffusional enzymatic electrodes. DOE is utilized as a tool for systematic organization and evaluation of various factors affecting the performance of the composite system. Based on the results from the DOE, an improved cathode is constructed. The current density generated utilizing the improved cathode (755 ± 39 μA cm-2 at 0.3 V vs. Ag/AgCl) is 2-5 times higher than the highest current density previously achieved. Three major factors contributing to the cathode performance are identified: the amount of enzyme, the volume of phosphate buffer used to immobilize the enzyme, and the thickness of the gas-diffusion layer (GDL). PCA is applied as an independent confirmation tool to support conclusions made by DOE and to visualize the contribution of factors in individual cathode configurations.

  18. Extended duration orbiter medical project Microbial Air Sampler (STS-50/USML-1)

    NASA Technical Reports Server (NTRS)

    Pierson, Duane L.; Boettcher, Sheila W.

    1994-01-01

    The Microbial Air Sampler was used on mission days 1, 7, and 13 in the Spacelab during STS-50/USML-1. Microbial air samples were collected using two types of media strips containing agar (Rose Bengal for yeast and molds, TSA for bacteria). The bacterial level found on day 1 was lower than experienced on previous Spacelab missions. A high level of fungi was present on day 1, however subsequent samples on days 7 and 13 did not indicate fungal growth. Bacterial growth was also minimized in this microgravity environment as the mission progressed. No pathogenic microorganisms were isolated, and the health risk from airborne microbes was minimal throughout the mission.

  19. Acetate enhances startup of a H₂-producing microbial biocathode.

    PubMed

    Jeremiasse, Adriaan W; Hamelers, Hubertus V M; Croese, Elsemiek; Buisman, Cees J N

    2012-03-01

    H(2) can be produced from organic matter with a microbial electrolysis cell (MEC). To decrease MEC capital costs, a cathode is needed that is made of low-cost material and produces H(2) at high rate. A microbial biocathode is a low-cost candidate, but suffers from a long startup and a low H(2) production rate. In this study, the effects of cathode potential and carbon source on microbial biocathode startup were investigated. Application of a more negative cathode potential did not decrease the startup time of the biocathode. If acetate instead of bicarbonate was used as carbon source, the biocathode started up more than two times faster. The faster startup was likely caused by a higher biomass yield for acetate than for bicarbonate, which was supported by thermodynamic calculations. To increase the H(2) production rate, a flow through biocathode fed with acetate was investigated. This biocathode produced 2.2 m(3) H(2) m(-3)  reactor day(-1) at a cathode potential of -0.7 V versus NHE, which was seven times that of a parallel flow biocathode of a previous study. Copyright © 2011 Wiley Periodicals, Inc.

  20. Treating refinery wastewaters in microbial fuel cells using separator electrode assembly or spaced electrode configurations.

    PubMed

    Zhang, Fang; Ahn, Yongtae; Logan, Bruce E

    2014-01-01

    The effectiveness of refinery wastewater (RW) treatment using air-cathode, microbial fuel cells (MFCs) was examined relative to previous tests based on completely anaerobic microbial electrolysis cells (MECs). MFCs were configured with separator electrode assembly (SEA) or spaced electrode (SPA) configurations to measure power production and relative impacts of oxygen crossover on organics removal. The SEA configuration produced a higher maximum power density (280±6 mW/m(2); 16.3±0.4 W/m(3)) than the SPA arrangement (255±2 mW/m(2)) due to lower internal resistance. Power production in both configurations was lower than that obtained with the domestic wastewater (positive control) due to less favorable (more positive) anode potentials, indicating poorer biodegradability of the RW. MFCs with RW achieved up to 84% total COD removal, 73% soluble COD removal and 92% HBOD removal. These removals were higher than those previously obtained in mini-MEC tests, as oxygen crossover from the cathode enhanced degradation in MFCs compared to MECs. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Semiquantitative Performance and Mechanism Evaluation of Carbon Nanomaterials as Cathode Coatings for Microbial Fouling Reduction.

    PubMed

    Zhang, Qiaoying; Nghiem, Joanne; Silverberg, Gregory J; Vecitis, Chad D

    2015-07-01

    In this study, we examine bacterial attachment and survival on a titanium (Ti) cathode coated with various carbon nanomaterials (CNM): pristine carbon nanotubes (CNT), oxidized carbon nanotubes (O-CNT), oxidized-annealed carbon nanotubes (OA-CNT), carbon black (CB), and reduced graphene oxide (rGO). The carbon nanomaterials were dispersed in an isopropyl alcohol-Nafion solution and were then used to dip-coat a Ti substrate. Pseudomonas fluorescens was selected as the representative bacterium for environmental biofouling. Experiments in the absence of an electric potential indicate that increased nanoscale surface roughness and decreased hydrophobicity of the CNM coating decreased bacterial adhesion. The loss of bacterial viability on the noncharged CNM coatings ranged from 22% for CB to 67% for OA-CNT and was dependent on the CNM dimensions and surface chemistry. For electrochemical experiments, the total density and percentage of inactivation of the adherent bacteria were analyzed semiquantitatively as functions of electrode potential, current density, and hydrogen peroxide generation. Electrode potential and hydrogen peroxide generation were the dominant factors with regard to short-term (3-h) bacterial attachment and inactivation, respectively. Extended-time electrochemical experiments (12 h) indicated that in all cases, the density of total deposited bacteria increased almost linearly with time and that the rate of bacterial adhesion was decreased 8- to 10-fold when an electric potential was applied. In summary, this study provides a fundamental rationale for the selection of CNM as cathode coatings and electric potential to reduce microbial fouling. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  2. Flavins secreted by bacterial cells of Shewanella catalyze cathodic oxygen reduction.

    PubMed

    Liu, Huan; Matsuda, Shoichi; Hashimoto, Kazuhito; Nakanishi, Shuji

    2012-06-01

    On Her Majesty's Secrete Service: Oxygen reduction is an important process for microbial fuel cells (MFCs) and microbiologically-influenced corrosion (MIC). We demonstrate that flavins secreted by anode-respiring Shewanella cells can catalyze cathodic oxygen reduction via adsorption on the cathode. The findings will provide new insight for developing methods to improve MFC performance and to prevent MIC. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Gradient porous electrode architectures for rechargeable metal-air batteries

    DOEpatents

    Dudney, Nancy J.; Klett, James W.; Nanda, Jagjit; Narula, Chaitanya Kumar; Pannala, Sreekanth

    2016-03-22

    A cathode for a metal air battery includes a cathode structure having pores. The cathode structure has a metal side and an air side. The porosity decreases from the air side to the metal side. A metal air battery and a method of making a cathode for a metal air battery are also disclosed.

  4. Microbial fuel cells: From fundamentals to applications. A review.

    PubMed

    Santoro, Carlo; Arbizzani, Catia; Erable, Benjamin; Ieropoulos, Ioannis

    2017-07-15

    In the past 10-15 years, the microbial fuel cell (MFC) technology has captured the attention of the scientific community for the possibility of transforming organic waste directly into electricity through microbially catalyzed anodic, and microbial/enzymatic/abiotic cathodic electrochemical reactions. In this review, several aspects of the technology are considered. Firstly, a brief history of abiotic to biological fuel cells and subsequently, microbial fuel cells is presented. Secondly, the development of the concept of microbial fuel cell into a wider range of derivative technologies, called bioelectrochemical systems, is described introducing briefly microbial electrolysis cells, microbial desalination cells and microbial electrosynthesis cells. The focus is then shifted to electroactive biofilms and electron transfer mechanisms involved with solid electrodes. Carbonaceous and metallic anode materials are then introduced, followed by an explanation of the electro catalysis of the oxygen reduction reaction and its behavior in neutral media, from recent studies. Cathode catalysts based on carbonaceous, platinum-group metal and platinum-group-metal-free materials are presented, along with membrane materials with a view to future directions. Finally, microbial fuel cell practical implementation, through the utilization of energy output for practical applications, is described.

  5. Microbial fuel cells: From fundamentals to applications. A review

    NASA Astrophysics Data System (ADS)

    Santoro, Carlo; Arbizzani, Catia; Erable, Benjamin; Ieropoulos, Ioannis

    2017-07-01

    In the past 10-15 years, the microbial fuel cell (MFC) technology has captured the attention of the scientific community for the possibility of transforming organic waste directly into electricity through microbially catalyzed anodic, and microbial/enzymatic/abiotic cathodic electrochemical reactions. In this review, several aspects of the technology are considered. Firstly, a brief history of abiotic to biological fuel cells and subsequently, microbial fuel cells is presented. Secondly, the development of the concept of microbial fuel cell into a wider range of derivative technologies, called bioelectrochemical systems, is described introducing briefly microbial electrolysis cells, microbial desalination cells and microbial electrosynthesis cells. The focus is then shifted to electroactive biofilms and electron transfer mechanisms involved with solid electrodes. Carbonaceous and metallic anode materials are then introduced, followed by an explanation of the electro catalysis of the oxygen reduction reaction and its behavior in neutral media, from recent studies. Cathode catalysts based on carbonaceous, platinum-group metal and platinum-group-metal-free materials are presented, along with membrane materials with a view to future directions. Finally, microbial fuel cell practical implementation, through the utilization of energy output for practical applications, is described.

  6. Simultaneous domestic wastewater treatment and renewable energy production using microbial fuel cells (MFCs).

    PubMed

    Puig, S; Serra, M; Coma, M; Balaguer, M D; Colprim, J

    2011-01-01

    Microbial fuel cells (MFCS) can be used in wastewater treatment and to simultaneously produce electricity (renewable energy). MFC technology has already been applied successfully in lab-scale studies to treat domestic wastewater, focussing on organic matter removal and energy production. However, domestic wastewater also contains nitrogen that needs to be treated before being discharged. The goal of this paper is to assess simultaneous domestic wastewater treatment and energy production using an air-cathode MFC, paying special attention to nitrogen compound transformations. An air-cathode MFC was designed and run treating 1.39 L d(-1) of wastewater with an organic load rate of 7.2 kg COD m(-3) d(-1) (80% removal efficiency) and producing 1.42 W m(-3). In terms of nitrogen transformations, the study demonstrates that two different processes took place in the MFC: physical-chemical and biological. Nitrogen loss was observed increasing in line with the power produced. A low level of oxygen was present in the anodic compartment, and ammonium was oxidised to nitrite and nitrate.

  7. Power generation from furfural using the microbial fuel cell

    NASA Astrophysics Data System (ADS)

    Luo, Yong; Liu, Guangli; Zhang, Renduo; Zhang, Cuiping

    Furfural is a typical inhibitor in the ethanol fermentation process using lignocellulosic hydrolysates as raw materials. In the literature, no report has shown that furfural can be utilized as the fuel to produce electricity in the microbial fuel cell (MFC), a device that uses microbes to convert organic compounds to generate electricity. In this study, we demonstrated that electricity was successfully generated using furfural as the sole fuel in both the ferricyanide-cathode MFC and the air-cathode MFC. In the ferricyanide-cathode MFC, the maximum power densities reached 45.4, 81.4, and 103 W m -3, respectively, when 1000 mg L -1 glucose, a mixture of 200 mg L -1 glucose and 5 mM furfural, and 6.68 mM furfural were used as the fuels in the anode solution. The corresponding Coulombic efficiencies (CE) were 4.0, 7.1, and 10.2% for the three treatments, respectively. For pure furfural as the fuel, the removal efficiency of furfural reached up to 95% within 12 h. In the air-cathode MFC using 6.68 mM furfural as the fuel, the maximum values of power density and CE were 361 mW m -2 (18 W m -3) and 30.3%, respectively, and the COD removal was about 68% at the end of the experiment (about 30 h). Increase in furfural concentrations from 6.68 to 20 mM resulted in increase in the maximum power densities from 361 to 368 mW m -2, and decrease in CEs from 30.3 to 20.6%. These results indicated that some toxic and biorefractory organics such as furfural might still be suitable resources for electricity generation using the MFC technology.

  8. Fabricating Ir/C Nanofiber Networks as Free-Standing Air Cathodes for Rechargeable Li-CO2 Batteries.

    PubMed

    Wang, Chengyi; Zhang, Qinming; Zhang, Xin; Wang, Xin-Gai; Xie, Zhaojun; Zhou, Zhen

    2018-06-07

    Li-CO 2 batteries are promising energy storage systems by utilizing CO 2 at the same time, though there are still some critical barriers before its practical applications such as high charging overpotential and poor cycling stability. In this work, iridium/carbon nanofibers (Ir/CNFs) are prepared via electrospinning and subsequent heat treatment, and are used as cathode catalysts for rechargeable Li-CO 2 batteries. Benefitting from the unique porous network structure and the high activity of ultrasmall Ir nanoparticles, Ir/CNFs exhibit excellent CO 2 reduction and evolution activities. The Li-CO 2 batteries present extremely large discharge capacity, high coulombic efficiency, and long cycling life. Moreover, free-standing Ir/CNF films are used directly as air cathodes to assemble Li-CO 2 batteries, which show high energy density and ultralong operation time, demonstrating great potential for practical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Modified High-Nickel Cathodes with Stable Surface Chemistry Against Ambient Air for Lithium-Ion Batteries.

    PubMed

    You, Ya; Celio, Hugo; Li, Jianyu; Dolocan, Andrei; Manthiram, Arumugam

    2018-03-30

    High-Ni layered oxides are promising next-generation cathodes for lithium-ion batteries owing to their high capacity and lower cost. However, as the Ni content increases over 70 %, they have a high dynamic affinity towards moisture and CO 2 in ambient air, primarily reacting to form LiOH, Li 2 CO 3 , and LiHCO 3 on the surface, which is commonly termed "residual lithium". Air exposure occurs after synthesis as it is common practice to handle and store them under ambient conditions. The air exposure leads to significant performance losses, and hampers the electrode fabrication, impeding their practical viability. Herein, we show that substituting a small amount of Al for Ni in the crystal lattice notably improves the chemical stability against air by limiting the formation of LiOH, Li 2 CO 3 , LiHCO 3 , and NiO in the near-surface region. The Al-doped high-Ni oxides display a high capacity retention with excellent rate capability and cycling stability after being exposed to air for 30 days. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. In Situ Imaging the Oxygen Reduction Reactions of Solid State Na-O2 Batteries with CuO Nanowires as the Air Cathode.

    PubMed

    Liu, Qiunan; Yang, Tingting; Du, Congcong; Tang, Yongfu; Sun, Yong; Jia, Peng; Chen, Jingzhao; Ye, Hongjun; Shen, Tongde; Peng, Qiuming; Zhang, Liqiang; Huang, Jianyu

    2018-06-13

    We report real time imaging of the oxygen reduction reactions (ORRs) in all solid state sodium oxygen batteries (SOBs) with CuO nanowires (NWs) as the air cathode in an aberration-corrected environmental transmission electron microscope under an oxygen environment. The ORR occurred in a distinct two-step reaction, namely, a first conversion reaction followed by a second multiple ORR. In the former, CuO was first converted to Cu 2 O and then to Cu; in the latter, NaO 2 formed first, followed by its disproportionation to Na 2 O 2 and O 2 . Concurrent with the two distinct electrochemical reactions, the CuO NWs experienced multiple consecutive large volume expansions. It is evident that the freshly formed ultrafine-grained Cu in the conversion reaction catalyzed the latter one-electron-transfer ORR, leading to the formation of NaO 2 . Remarkably, no carbonate formation was detected in the oxygen cathode after cycling due to the absence of carbon source in the whole battery setup. These results provide fundamental understanding into the oxygen chemistry in the carbonless air cathode in all solid state Na-O 2 batteries.

  11. Microbial safety of air-dried and rewetted biosolids.

    PubMed

    Rouch, Duncan A; Mondal, Tania; Pai, Sneha; Glauche, Florian; Fleming, Vennessa A; Thurbon, Nerida; Blackbeard, Judy; Smith, Stephen R; Deighton, Margaret

    2011-06-01

    To assess microbial safety of treated sewage sludge (biosolids), we examined the inactivation of microbial indicators for potential bacterial, viral and protozoan pathogens. The levels of indicators were determined throughout the air-drying and storage phases of anaerobically digested sewage sludge. Samples were collected from two wastewater treatment plants (WWTPS) in Victoria, Australia. Established methods were applied for analysis of bacteria and coliphages, based on membrane filtration and layered plates, respectively. In the pan drying phase, the prevalence of Escherichia coli was reduced by >5 log10 compared with sludge entering the pan. Thus, after pan drying of 8-11 months at WWTP A and 15 months at WWTP B, the numbers of E. coli were reduced to below 10(2) cfu/g dry solids (DS). This level is acceptable for unrestricted use in agriculture in Australia (P1 treatment grade), the UK (enhanced treatment status) and the USA (Class A pathogen reduction). Coliphage numbers also decreased substantially during the air-drying phase, indicating that enteric viruses are also likely to be destroyed during this phase. Clostridium perfringens appeared to be an overly conservative indicator. Survival, but not regrowth, of E. coli or Salmonella was observed in rewetted biosolids (15-20% moisture content), after being seeded with these species, indicating a degree of safety of stored biosolids upon rewetting by rain.

  12. Simultaneous sulfide removal, nitrification, and electricity generation in a microbial fuel cell equipped with an oxic cathode.

    PubMed

    Bao, Renbing; Zhang, Shaohui; Zhao, Li; Zhong, Liuxiang

    2017-02-01

    With sulfide as an anodic electron donor and ammonium as a cathodic substrate, the feasibility of simultaneous sulfide removal, nitrification, and electricity generation was investigated in a microbial fuel cell (MFC) equipped with an oxic cathode. Successful simultaneous sulfide removal, nitrification, and electricity generation in this MFC were achieved in 35 days, with the sulfide and ammonium removal percent of 92.7 ± 1.4 and 96.4 ± 0.3%, respectively. The maximum power density increased, but the internal resistance decreased with the increase of feeding sulfide concentration from 62.9 ± 0.3 to 238.5 ± 0.2 mg S/L. Stable ammonium removal with complete nitrification, preparing for future denitrification, was obtained throughout the current study. Sulfide removal loading significantly increased with the increase of feeding sulfide concentration at each external resistance, but no significant correlation between sulfide removal loading and external resistance was found at each feeding sulfide concentration. The charge recovery and anodic coulombic efficiency (CE) significantly decreased with the increase of external resistance. High feeding sulfide concentration led to low anodic CE. Granular sulfur deposition was found on the anode graphite fiber. The appropriate feeding sulfide concentration for sulfide removal and sulfur deposition was deemed to be 178.0 ± 1.7 mg S/L, achieving a sulfur deposition percent of 69.7 ± 0.6%.

  13. Microbial communities related to volatile organic compound emission in automobile air conditioning units.

    PubMed

    Diekmann, Nina; Burghartz, Melanie; Remus, Lars; Kaufholz, Anna-Lena; Nawrath, Thorben; Rohde, Manfred; Schulz, Stefan; Roselius, Louisa; Schaper, Jörg; Mamber, Oliver; Jahn, Dieter; Jahn, Martina

    2013-10-01

    During operation of mobile air conditioning (MAC) systems in automobiles, malodours can occur. We studied the microbial communities found on contaminated heat exchanger fins of 45 evaporators from car MAC systems which were operated in seven different regions of the world and identified corresponding volatile organic compounds. Collected biofilms were examined by scanning electron microscopy and fluorescent in situ hybridization. The detected bacteria were loosely attached to the metal surface. Further analyses of the bacteria using PCR-based single-strand conformation polymorphism and sequencing of isolated 16S rRNA gene fragments identified highly divergent microbial communities with multiple members of the Alphaproteobacteriales, Methylobacteria were the prevalent bacteria. In addition, Sphingomonadales, Burkholderiales, Bacillales, Alcanivorax spp. and Stenotrophomonas spp. were found among many others depending on the location the evaporators were operated. Interestingly, typical pathogenic bacteria related to air conditioning systems including Legionella spp. were not found. In order to determine the nature of the chemical compounds produced by the bacteria, the volatile organic compounds were examined by closed loop stripping analysis and identified by combined gas chromatography/mass spectrometry. Sulphur compounds, i.e. di-, tri- and multiple sulphides, acetylthiazole, aromatic compounds and diverse substituted pyrazines were detected. Mathematical clustering of the determined microbial community structures against their origin identified a European/American/Arabic cluster versus two mainly tropical Asian clusters. Interestingly, clustering of the determined volatiles against the origin of the corresponding MAC revealed a highly similar pattern. A close relationship of microbial community structure and resulting malodours to the climate and air quality at the location of MAC operation was concluded.

  14. Forced-air warming design: evaluation of intake filtration, internal microbial buildup, and airborne-contamination emissions.

    PubMed

    Reed, Mike; Kimberger, Oliver; McGovern, Paul D; Albrecht, Mark C

    2013-08-01

    Forced-air warming devices are effective for the prevention of surgical hypothermia. However, these devices intake nonsterile floor-level air, and it is unknown whether they have adequate filtration measures to prevent the internal buildup or emission of microbial contaminants. We rated the intake filtration efficiency of a popular current-generation forced-air warming device (Bair Hugger model 750, Arizant Healthcare) using a monodisperse sodium chloride aerosol in the laboratory. We further sampled 23 forced-air warming devices (same model) in daily hospital use for internal microbial buildup and airborne-contamination emissions via swabbing and particle counting. Laboratory testing found the intake filter to be 63.8% efficient. Swabbing detected microorganisms within 100% of the forced-air warming blowers sampled, with isolates of coagulase-negative staphylococci, mold, and micrococci identified. Particle counting showed 96% of forced-air warming blowers to be emitting significant levels of internally generated airborne contaminants out of the hose end. These findings highlight the need for upgraded intake filtration, preferably high-efficiency particulate air filtration (99.97% efficient), on current-generation forced-air warming devices to reduce contamination buildup and emission risks.

  15. Pyrolyzed binuclear-cobalt-phthalocyanine as electrocatalyst for oxygen reduction reaction in microbial fuel cells.

    PubMed

    Li, Baitao; Wang, Mian; Zhou, Xiuxiu; Wang, Xiujun; Liu, Bingchuan; Li, Baikun

    2015-10-01

    A novel platinum (Pt)-free cathodic materials binuclear-cobalt-phthalocyanine (Bi-CoPc) pyrolyzed at different temperatures (300-1000 °C) were examined as the oxygen reduction reaction (ORR) catalysts, and compared with unpyrolyzed Bi-CoPc/C and Pt cathode in single chamber microbial fuel cells (SCMFCs). The results showed that the pyrolysis process increased the nitrogen abundance on Bi-CoPc and changed the nitrogen types. The Bi-CoPc pyrolyzed at 800 °C contained a significant amount of pyrrolic-N, and exhibited a high electrochemical catalytic activity. The power density and current density increased with temperature: Bi-CoPc/C-800 > Bi-CoPc/C-1000 > Bi-CoPc/C-600 > Bi-CoPc/C-300 > Bi-CoPc/C. The SCMFC with Bi-CoPc/C-800 cathode had a maximum power density of 604 mW m(-2). The low cost Bi-CoPc compounds developed in this study showed a potential in air-breathing MFC systems, with the proper pyrolysis temperature being chosen. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Seasonal Variations of Indoor Microbial Exposures and Their Relation to Temperature, Relative Humidity, and Air Exchange Rate

    PubMed Central

    Bekö, Gabriel; Timm, Michael; Gustavsen, Sine; Hansen, Erik Wind

    2012-01-01

    Indoor microbial exposure has been related to adverse pulmonary health effects. Exposure assessment is not standardized, and various factors may affect the measured exposure. The aim of this study was to investigate the seasonal variation of selected microbial exposures and their associations with temperature, relative humidity, and air exchange rates in Danish homes. Airborne inhalable dust was sampled in five Danish homes throughout the four seasons of 1 year (indoors, n = 127; outdoors, n = 37). Measurements included culturable fungi and bacteria, endotoxin, N-acetyl-beta-d-glucosaminidase, total inflammatory potential, particles (0.75 to 15 μm), temperature, relative humidity, and air exchange rates. Significant seasonal variation was found for all indoor microbial exposures, excluding endotoxin. Indoor fungi peaked in summer (median, 235 CFU/m3) and were lowest in winter (median, 26 CFU/m3). Indoor bacteria peaked in spring (median, 2,165 CFU/m3) and were lowest in summer (median, 240 CFU/m3). Concentrations of fungi were predominately higher outdoors than indoors, whereas bacteria, endotoxin, and inhalable dust concentrations were highest indoors. Bacteria and endotoxin correlated with the mass of inhalable dust and number of particles. Temperature and air exchange rates were positively associated with fungi and N-acetyl-beta-d-glucosaminidase and negatively with bacteria and the total inflammatory potential. Although temperature, relative humidity, and air exchange rates were significantly associated with several indoor microbial exposures, they could not fully explain the observed seasonal variations when tested in a mixed statistical model. In conclusion, the season significantly affects indoor microbial exposures, which are influenced by temperature, relative humidity, and air exchange rates. PMID:23001651

  17. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell

    PubMed Central

    Dong, Feng; Zhang, Peng; Li, Kexun; Liu, Xianhua; Zhang, Pingping

    2016-01-01

    In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode. PMID:28335366

  18. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell.

    PubMed

    Dong, Feng; Zhang, Peng; Li, Kexun; Liu, Xianhua; Zhang, Pingping

    2016-12-09

    In this work, Cu₂O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode.

  19. Electricity generation and microbial community analysis of alcohol powered microbial fuel cells.

    PubMed

    Kim, Jung Rae; Jung, Sok Hee; Regan, John M; Logan, Bruce E

    2007-09-01

    Two different microbial fuel cell (MFC) configurations were investigated for electricity production from ethanol and methanol: a two-chambered, aqueous-cathode MFC; and a single-chamber direct-air cathode MFC. Electricity was generated in the two-chamber system at a maximum power density typical of this system (40+/-2 mW/m2) and a Coulombic efficiency (CE) ranging from 42% to 61% using ethanol. When bacteria were transferred into a single-chamber MFC known to produce higher power densities with different substrates, the maximum power density increased to 488+/-12 mW/m2 (CE = 10%) with ethanol. The voltage generated exhibited saturation kinetics as a function of ethanol concentration in the two-chambered MFC, with a half-saturation constant (Ks) of 4.86 mM. Methanol was also examined as a possible substrate, but it did not result in appreciable electricity generation. Analysis of the anode biofilm and suspension from a two-chamber MFC with ethanol using 16S rDNA-based techniques indicated that bacteria with sequences similar to Proteobacterium Core-1 (33.3% of clone library sequences), Azoarcus sp. (17.4%), and Desulfuromonas sp. M76 (15.9%) were significant members of the anode chamber community. These results indicate that ethanol can be used for sustained electricity generation at room temperature using bacteria on the anode in a MFC.

  20. Microbial contamination of dental unit waterlines and effect on quality of indoor air.

    PubMed

    Kadaifciler, Duygu Göksay; Cotuk, Aysin

    2014-06-01

    The microbiological quality in dental unit waterlines (DUWLs) is considered to be important because patients and dental staff with suppressed immune systems are regularly exposed to water and aerosols generated from dental units (DUs). Opportunistic pathogens like Pseudomonas, Legionella, Candida, and Aspergillus can be present in DUWLs, while during consultations, bioaerosols can be dispersed in the air, thus resulting in effects on microbiological quality of indoor air. This present study represents microbiological air and water quality in dental offices (DOs) and also concerns the relationship between the quality of DO air and dental unit water. This study aimed to assess both the microbial quality of dental unit water and the indoor air in 20 DOs and to survey the effect on the quality of the indoor air with the existing microorganisms in dental unit water. Fourteen out of 20 (70 %) DUWLs were found to be contaminated with a high number of aerobic mesophilic heterotrophic bacteria. In terms of bacterial air contamination levels, in 90 % of DOs, a medium level (<500 colony-forming units (CFU)/m(3)) of contamination was determined, while in terms of microfungal air contamination, in all DOs, a low level (<100 CFU/m(3)) of contamination was determined. Potential infection or allergen agents, such as Pseudomonas, Micrococcus, Staphylococcus, Alternaria, Cladosporium, Penicillium, Aspergillus, and Paecilomyces were isolated from water and air samples. This study's determination of contamination sources and evaluation of microbial load in DOs could contribute to the development of quality control methods in the future.

  1. Evaluation of activated carbon adsorbent for fuel cell cathode air filtration

    NASA Astrophysics Data System (ADS)

    Ma, Xiaowei; Yang, Daijun; Zhou, Wei; Zhang, Cunman; Pan, Xiangmin; Xu, Lin; Wu, Minzhong; Ma, Jianxin

    The effectiveness of a commercial activated carbon modified by KOH (KMAC) was evaluated as adsorbent for purifying NO x and SO 2, which are the major contaminants in fuel cell cathode air stream. The N 2 adsorption-desorption isotherms of KMAC samples showed that the surface structure of the activated carbon was changed significantly by KOH impregnation. The sample of KMAC with a loading of 10.1% KOH by weight presented the highest adsorption capacities for both NO x and SO 2, which were 96 mg g -1 and 255 mg g -1, respectively. A pre-exposure of KMAC to CO 2 caused neither effect on the adsorption of NO x nor on the adsorption of SO 2. KMAC could fully protect a 250 W proton exchange membrane fuel cell (PEMFC) stack from 1100 ppb of NO x and 250 ppb of SO 2 for about 130 h.

  2. Deep sea microbial fuel cell output as a proxy for microbial activity

    NASA Astrophysics Data System (ADS)

    Richter, K.; George, R.; Hardy, K. R.

    2016-02-01

    Abstract: Microbial fuel cells (MFCs) work by providing bacteria in anaerobic sediments with an electron acceptor (anode) that stimulates metabolism of organic matter. The buried anode is connected via control circuitry to a cathode exposed to oxygen in the overlying water. During metabolism, bacteria release hydrogen ions into the sediment and transfer electrons extra-cellularly to the anode, which eventually reduce dissolved oxygen at the cathode, forming water. The current is chiefly limited by the rate of microbial metabolism at the anode and serves as a proxy for microbial activity. The Office of Naval Research has encouraged development of microbial fuel cells in the marine environment at a number of academic and naval institutions and studies of important environmental parameters that affect fuel cell performance. Earlier work in shallow sediments of San Diego Bay showed that the most important environmental parameters that control fuel cell power output in San Diego Bay were total organic carbon in the sediment and seasonal water temperature. Current MFC work at SPAWAR includes extension of microbial fuel cell tests to the deep sea environment (>4000 m) and, in parallel, testing microbial fuel cells in the laboratory under deep sea conditions. We are pursuing a field efforts to deploy a microbial fuel cell in progressively deeper water, record in situ power and temperature over several weeks, and retrieve the fuel cell along with sediment samples for analysis. We are also pursuing a laboratory effort to build a matching microbial fuel cell in a pressure vessel capable of matching the pressure and temperature of deep water, and stocking the pressure vessel with deep water sediment in order to take measurements analogous to those in the field. We also hope to determine whether bacteria growing on the anode are different from bacteria growing in the bulk sediment via DNA analysis. The current progress and results from this work at SPAWAR will be presented.

  3. Microbial Air Quality and Bacterial Surface Contamination in Ambulances During Patient Services

    PubMed Central

    Luksamijarulkul, Pipat; Pipitsangjan, Sirikun

    2015-01-01

    Objectives We sought to assess microbial air quality and bacterial surface contamination on medical instruments and the surrounding areas among 30 ambulance runs during service. Methods We performed a cross-sectional study of 106 air samples collected from 30 ambulances before patient services and 212 air samples collected during patient services to assess the bacterial and fungal counts at the two time points. Additionally, 226 surface swab samples were collected from medical instrument surfaces and the surrounding areas before and after ambulance runs. Groups or genus of isolated bacteria and fungi were preliminarily identified by Gram’s stain and lactophenol cotton blue. Data were analyzed using descriptive statistics, t-test, and Pearson’s correlation coefficient with a p-value of less than 0.050 considered significant. Results The mean and standard deviation of bacterial and fungal counts at the start of ambulance runs were 318±485cfu/m3 and 522±581cfu/m3, respectively. Bacterial counts during patient services were 468±607cfu/m3 and fungal counts were 656±612cfu/m3. Mean bacterial and fungal counts during patient services were significantly higher than those at the start of ambulance runs, p=0.005 and p=0.030, respectively. For surface contamination, the overall bacterial counts before and after patient services were 0.8±0.7cfu/cm2 and 1.3±1.1cfu/cm2, respectively (p<0.001). The predominant isolated bacteria and fungi were Staphylococcus spp. and Aspergillus spp., respectively. Additionally, there was a significantly positive correlation between bacterial (r=0.3, p<0.010) and fungal counts (r=0.2, p=0.020) in air samples and bacterial counts on medical instruments and allocated areas. Conclusions This study revealed high microbial contamination (bacterial and fungal) in ambulance air during services and higher bacterial contamination on medical instrument surfaces and allocated areas after ambulance services compared to the start of ambulance runs

  4. Microbial air quality and bacterial surface contamination in ambulances during patient services.

    PubMed

    Luksamijarulkul, Pipat; Pipitsangjan, Sirikun

    2015-03-01

    We sought to assess microbial air quality and bacterial surface contamination on medical instruments and the surrounding areas among 30 ambulance runs during service. We performed a cross-sectional study of 106 air samples collected from 30 ambulances before patient services and 212 air samples collected during patient services to assess the bacterial and fungal counts at the two time points. Additionally, 226 surface swab samples were collected from medical instrument surfaces and the surrounding areas before and after ambulance runs. Groups or genus of isolated bacteria and fungi were preliminarily identified by Gram's stain and lactophenol cotton blue. Data were analyzed using descriptive statistics, t-test, and Pearson's correlation coefficient with a p-value of less than 0.050 considered significant. The mean and standard deviation of bacterial and fungal counts at the start of ambulance runs were 318±485cfu/m(3) and 522±581cfu/m(3), respectively. Bacterial counts during patient services were 468±607cfu/m(3) and fungal counts were 656±612cfu/m(3). Mean bacterial and fungal counts during patient services were significantly higher than those at the start of ambulance runs, p=0.005 and p=0.030, respectively. For surface contamination, the overall bacterial counts before and after patient services were 0.8±0.7cfu/cm(2) and 1.3±1.1cfu/cm(2), respectively (p<0.001). The predominant isolated bacteria and fungi were Staphylococcus spp. and Aspergillus spp., respectively. Additionally, there was a significantly positive correlation between bacterial (r=0.3, p<0.010) and fungal counts (r=0.2, p=0.020) in air samples and bacterial counts on medical instruments and allocated areas. This study revealed high microbial contamination (bacterial and fungal) in ambulance air during services and higher bacterial contamination on medical instrument surfaces and allocated areas after ambulance services compared to the start of ambulance runs. Additionally, bacterial and

  5. Metal-Organic-Framework-Derived Dual Metal- and Nitrogen-Doped Carbon as Efficient and Robust Oxygen Reduction Reaction Catalysts for Microbial Fuel Cells.

    PubMed

    Tang, Haolin; Cai, Shichang; Xie, Shilei; Wang, Zhengbang; Tong, Yexiang; Pan, Mu; Lu, Xihong

    2016-02-01

    A new class of dual metal and N doped carbon catalysts with well-defined porous structure derived from metal-organic frameworks (MOFs) has been developed as a high-performance electrocatalyst for oxygen reduction reaction (ORR). Furthermore, the microbial fuel cell (MFC) device based on the as-prepared Ni/Co and N codoped carbon as air cathode catalyst achieves a maximum power density of 4335.6 mW m -2 and excellent durability.

  6. Hollow-Cathode Source Generates Plasma

    NASA Technical Reports Server (NTRS)

    Deininger, W. D.; Aston, G.; Pless, L. C.

    1989-01-01

    Device generates argon, krypton, or xenon plasma via thermionic emission and electrical discharge within hollow cathode and ejects plasma into surrounding vacuum. Goes from cold start up to full operation in less than 5 s after initial application of power. Exposed to moist air between operations without significant degradation of starting and running characteristics. Plasma generated by electrical discharge in cathode barrel sustained and aided by thermionic emission from emitter tube. Emitter tube does not depend on rare-earth oxides, making it vulnerable to contamination by exposure to atmosphere. Device modified for use as source of plasma in laboratory experiments or industrial processes.

  7. Quantification of the internal resistance distribution of microbial fuel cells.

    PubMed

    Fan, Yanzhen; Sharbrough, Evan; Liu, Hong

    2008-11-01

    Identifying the limiting factors in a microbial fuel cell (MFC) system requires qualifying the contribution of each component of an MFC to internal resistance. In this study, a new method was developed to calculate the internal resistance distribution of an MFC. Experiments were conducted to identify the limiting factors in single-chamber MFCs by varying the anode surface areas, cathode surface areas, and phosphate buffer concentrations. For the MFCs with equally sized electrodes (7 cm2) and 200 mM phosphate buffer, the anode contributed just 5.4% of the internal resistance, while the cathode and the electrolyte each contributed 47.3%, indicating that the anode was not the limiting factor in power generation. The limitation of the cathode was further revealed by the 780% higher area-specific resistance (284.4 omega cm2) than the 32.3 omega cm2 of the anode. The electrolyte limitation was also evidenced by the greatly increased contribution of electrolyte in internal resistance from 47.3 to 78.2% when the concentration of phosphate buffer was decreased from 200 to 50 mM. An anodic power density of 6860 mW/m2 was achieved at a current density of 2.62 mA/cm2 using the MFCs with an anode/cathode area ratio of 1/14 and 200 mM phosphate buffer. The method was also successfully applied to analyze the internal resistance distribution of the two chamber MFCs from a previously reported study. The comparison of the internal resistances of the two air cathode systems indicates that the much lower resistances, including anode, cathode, and membrane resistances, contributed to the much better performance of the single-chamber MFCs than the two-chamber system.

  8. Micro-sized microbial fuel cell: a mini-review.

    PubMed

    Wang, Hsiang-Yu; Bernarda, Angela; Huang, Chih-Yung; Lee, Duu-Jong; Chang, Jo-Shu

    2011-01-01

    This review presents the development of micro-sized microbial fuel cells (including mL-scale and μL-scale setups), with summarization of their advantageous characteristics, fabrication methods, performances, potential applications and possible future directions. The performance of microbial fuel cells (MFCs) is affected by issues such as mass transport, reaction kinetics and ohmic resistance. These factors are manipulated in micro-sized MFCs using specially allocated electrodes constructed with specified materials having physically or chemically modified surfaces. Both two-chamber and air-breathing cathodes are promising configurations for mL-scale MFCs. However, most of the existing μL-scale MFCs generate significantly lower volumetric power density compared with their mL-counterparts because of the high internal resistance. Although μL-scale MFCs have not yet to provide sufficient power for operating conventional equipment, they show great potential in rapid screening of electrochemically microbes and electrode performance. Additional possible applications and future directions are also provided for the development of micro-sized MFCs. Copyright © 2010 Elsevier Ltd. All rights reserved.

  9. Complete cobalt recovery from lithium cobalt oxide in self-driven microbial fuel cell - Microbial electrolysis cell systems

    NASA Astrophysics Data System (ADS)

    Huang, Liping; Yao, Binglin; Wu, Dan; Quan, Xie

    2014-08-01

    Complete cobalt recovery from lithium cobalt oxide requires to firstly leach cobalt from particles LiCoO2 and then recover cobalt from aqueous Co(II). A self-driven microbial fuel cell (MFC)-microbial electrolysis cell (MEC) system can completely carry out these two processes, in which Co(II) is firstly released from particles LiCoO2 on the cathodes of MFCs and then reduced on the cathodes of MECs which are powered by the cobalt leaching MFCs. A cobalt leaching rate of 46 ± 2 mg L-1 h-1 with yield of 1.5 ± 0.1 g Co g-1 COD (MFCs) and a Co(II) reduction rate of 7 ± 0 mg L-1 h-1 with yield of 0.8 ± 0.0 g Co g-1 COD (MECs), as well as a overall system cobalt yield of 0.15 ± 0.01 g Co g-1 Co can be achieved in this self-driven MFC-MEC system. Coulombic efficiencies reach 41 ± 1% (anodic MFCs), 75 ± 0% (anodic MECs), 100 ± 2% (cathodic MFCs), and 29 ± 1% (cathodic MECs) whereas overall system efficiency averages 34 ± 1%. These results provide a new process of linking MFCs to MECs for complete recovery of cobalt and recycle of spent lithium ion batteries with no external energy consumption.

  10. Co-flow anode/cathode supply heat exchanger for a solid-oxide fuel cell assembly

    DOEpatents

    Haltiner, Jr., Karl J.; Kelly, Sean M.

    2005-11-22

    In a solid-oxide fuel cell assembly, a co-flow heat exchanger is provided in the flow paths of the reformate gas and the cathode air ahead of the fuel cell stack, the reformate gas being on one side of the exchanger and the cathode air being on the other. The reformate gas is at a substantially higher temperature than is desired in the stack, and the cathode gas is substantially cooler than desired. In the co-flow heat exchanger, the temperatures of the reformate and cathode streams converge to nearly the same temperature at the outlet of the exchanger. Preferably, the heat exchanger is formed within an integrated component manifold (ICM) for a solid-oxide fuel cell assembly.

  11. Microbial Air and Surface Monitoring Results from International Space Station Samples

    NASA Technical Reports Server (NTRS)

    Ott, C. Mark; Bruce, Rebekah J.; Castro, Victoria A.; Novikova, Natalia D.; Pierson, D. L.

    2005-01-01

    Over the course of long-duration spaceflight, spacecraft develop a microbial ecology that directly interacts with the crew of the vehicle. While most microorganisms are harmless or beneficial to the inhabitants of the vehicle, the presence of medically significant organisms appearing in this semi-closed environment could adversely affect crew health and performance. The risk of exposure of the crew to medically significant organisms during a mission is estimated using information gathered during nominal and contingency environmental monitoring. Analysis of the air and surface microbiota in the habitable compartments of the International Space Station (ISS) over the last four years indicate a high presence of Staphylococcus species reflecting the human inhabitants of the vehicle. Generally, air and surface microbial concentrations are below system design specifications, suggesting a lower risk of contact infection or biodegradation. An evaluation of sample frequency indicates a decrease in the identification of new species, suggesting a lower potential for unknown microorganisms to be identified. However, the opportunistic pathogen, Staphylococcus aureus, has been identified in 3 of the last 5 air samples and 5 of the last 9 surface samples. In addition, 47% of the coagulase negative Staphylococcus species that were isolated from the crew, ISS, and its hardware were found to be methicillin resistance. In combination, these observations suggest the potential of methicillin resistant infectious agents over time.

  12. Highly exposed Fe-N4 active sites in porous poly-iron-phthalocyanine based oxygen reduction electrocatalyst with ultrahigh performance for air cathode.

    PubMed

    Anandhababu, Ganesan; Abbas, Syed Comail; Lv, Jiangquan; Ding, Kui; Liu, Qin; Babu, Dickson D; Huang, Yiyin; Xie, Jiafang; Wu, Maoxiang; Wang, Yaobing

    2017-02-14

    Progress in the development of efficient electrocatalysts for oxygen reduction reactions is imperative for various energy systems such as metal-air batteries and fuel cells. In this paper, an innovative porous two-dimensional (2D) poly-iron-phthalocyanine (PFe-Pc) based oxygen reduction electrocatalyst created with a simple solid-state chemical reaction without pyrolysis is reported. In this strategy, silicon dioxide nanoparticles play a pivotal role in preserving the Fe-N 4 structure during the polymerization process and thereby assist in the development of a porous structure. The new polymerized phthalocyanine electrocatalyst with tuned porous structure, improved specific surface area and more exposed catalytic active sites via the 2D structure shows an excellent performance towards an oxygen reduction reaction in alkaline media. The onset potential (E = 1.033 V) and limiting current density (I = 5.58 mA cm -2 ) are much better than those obtained with the commercial 20% platinum/carbon electrocatalyst (1.046 V and 4.89 mA cm -2 ) and also show better stability and tolerance to methanol crossover. For practical applications, a zinc-air (Zn-air) battery and methanol fuel cell equipped with the PFe-Pc electrocatalyst as an air cathode reveal a high open circuit voltage and maximum power output (1.0 V and 23.6 mW cm -2 for a methanol fuel cell, and 1.6 V and 192 mW cm -2 for the liquid Zn-air battery). In addition, using the PFe-Pc electrocatalyst as an air cathode in a flexible cable-type Zn-air battery exhibits excellent performance with an open-circuit voltage of 1.409 V. This novel porous 2D PFe-Pc has been designed logically using a new, simple strategy with ultrahigh electrochemical performances in Zn-air batteries and methanol fuel cell applications.

  13. An Overview of Electron Acceptors in Microbial Fuel Cells

    PubMed Central

    Ucar, Deniz; Zhang, Yifeng; Angelidaki, Irini

    2017-01-01

    Microbial fuel cells (MFC) have recently received increasing attention due to their promising potential in sustainable wastewater treatment and contaminant removal. In general, contaminants can be removed either as an electron donor via microbial catalyzed oxidization at the anode or removed at the cathode as electron acceptors through reduction. Some contaminants can also function as electron mediators at the anode or cathode. While previous studies have done a thorough assessment of electron donors, cathodic electron acceptors and mediators have not been as well described. Oxygen is widely used as an electron acceptor due to its high oxidation potential and ready availability. Recent studies, however, have begun to assess the use of different electron acceptors because of the (1) diversity of redox potential, (2) needs of alternative and more efficient cathode reaction, and (3) expanding of MFC based technologies in different areas. The aim of this review was to evaluate the performance and applicability of various electron acceptors and mediators used in MFCs. This review also evaluated the corresponding performance, advantages and disadvantages, and future potential applications of select electron acceptors (e.g., nitrate, iron, copper, perchlorate) and mediators. PMID:28469607

  14. Methane production enhancement by an independent cathode in integrated anaerobic reactor with microbial electrolysis.

    PubMed

    Cai, Weiwei; Han, Tingting; Guo, Zechong; Varrone, Cristiano; Wang, Aijie; Liu, Wenzong

    2016-05-01

    Anaerobic digestion (AD) represents a potential way to achieve energy recovery from waste organics. In this study, a novel bioelectrochemically-assisted anaerobic reactor is assembled by two AD systems separated by anion exchange membrane, with the cathode placing in the inside cylinder (cathodic AD) and the anode on the outside cylinder (anodic AD). In cathodic AD, average methane production rate goes up to 0.070 mL CH4/mL reactor/day, which is 2.59 times higher than AD control reactor (0.027 m(3) CH4/m(3)/d). And COD removal is increased ∼15% over AD control. When changing to sludge fermentation liquid, methane production rate has been further increased to 0.247 mL CH4/mL reactor/day (increased by 51.53% comparing with AD control). Energy recovery efficiency presents profitable gains, and economic revenue from increased methane totally self-cover the cost of input electricity. The study indicates that cathodic AD could cost-effectively enhance methane production rate and degradation of glucose and fermentative liquid. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. The Role of Soil Organic Matter, Nutrients, and Microbial Community Structure on the Performance of Microbial Fuel Cells

    NASA Astrophysics Data System (ADS)

    Rooney-Varga, J. N.; Dunaj, S. J.; Vallino, J. J.; Hines, M. E.; Gay, M.; Kobyljanec, C.

    2011-12-01

    Microbial fuel cells (MFCs) offer the potential for generating electricity, mitigating greenhouse gas emissions, and bioremediating pollutants through utilization of a plentiful, natural, and renewable resource: soil organic carbon. In the current study, we analyzed microbial community structure, MFC performance, and soil characteristics in different microhabitats (bulk soil, anode, and cathode) within MFCs constructed from agricultural or forest soils in order to determine how soil type and microbial dynamics influence MFC performance. MFCs were constructed with soils from agricultural and hardwood forest sites at Harvard Forest (Petersham, MA). The bulk soil characteristics were analyzed, including polyphenols, short chain fatty acids, total organic C and N, abiotic macronutrients, N and P mineralization rates, CO2 respiration rates, and MFC power output. Microbial community structure of the anodes, cathodes, and bulk soils was determined with molecular fingerprinting methods, which included terminal restriction length polymorphism (T-RFLP) analysis and 16S rRNA gene sequencing analysis. Our results indicated that MFCs constructed from agricultural soil had power output about 17 times that of forest soil-based MFCs and respiration rates about 10 times higher than forest soil MFCs. Agricultural soil MFCs had lower C:N ratios, polyphenol content, and acetate concentrations than forest soil MFCs, suggesting that active agricultural MFC microbial communities were supported by higher quality organic carbon. Microbial community profile data indicate that the microbial communities at the anode of the high power MFCs were less diverse than in low power MFCs and were dominated by Deltaproteobacteria, Geobacter, and, to a lesser extent, Clostridia, while low-power MFC anode communities were dominated by Clostridia. These data suggest that the presence of organic carbon substrate (acetate) was not the major limiting factor in selecting for highly electrogenic microbial

  16. Can Particulate Air Sampling Predict Microbial Load in Operating Theatres for Arthroplasty?

    PubMed Central

    Cristina, Maria Luisa; Spagnolo, Anna Maria; Sartini, Marina; Panatto, Donatella; Gasparini, Roberto; Orlando, Paolo; Ottria, Gianluca; Perdelli, Fernanda

    2012-01-01

    Several studies have proposed that the microbiological quality of the air in operating theatres be indirectly evaluated by means of particle counting, a technique derived from industrial clean-room technology standards, using airborne particle concentration as an index of microbial contamination. However, the relationship between particle counting and microbiological sampling has rarely been evaluated and demonstrated in operating theatres. The aim of the present study was to determine whether particle counting could predict microbiological contamination of the air in an operating theatre during 95 surgical arthroplasty procedures. This investigation was carried out over a period of three months in 2010 in an orthopedic operating theatre devoted exclusively to prosthetic surgery. During each procedure, the bacterial contamination of the air was determined by means of active sampling; at the same time, airborne particulate contamination was assessed throughout the entire procedure. On considering the total number of surgical operations, the mean value of the total bacterial load in the center of the operating theatre proved to be 35 CFU/m3; the mean particle count was 4,194,569 no./m3 for particles of diameter ≥0.5 µm and 13,519 no./m3 for particles of diameter ≥5 µm. No significant differences emerged between the median values of the airborne microbial load recorded during the two types of procedure monitored. Particulates with a diameter of ≥0.5 µm were detected in statistically higher concentrations (p<0.001) during knee-replacement procedures. By contrast, particulates with a diameter of ≥5 µm displayed a statistically higher concentration during hip-replacement procedures (p<0.05). The results did not reveal any statistically significant correlation between microbial loads and particle counts for either of the particle diameters considered (≥0.5 µm and ≥5 µm). Consequently, microbiological monitoring remains the most suitable method of

  17. Can particulate air sampling predict microbial load in operating theatres for arthroplasty?

    PubMed

    Cristina, Maria Luisa; Spagnolo, Anna Maria; Sartini, Marina; Panatto, Donatella; Gasparini, Roberto; Orlando, Paolo; Ottria, Gianluca; Perdelli, Fernanda

    2012-01-01

    Several studies have proposed that the microbiological quality of the air in operating theatres be indirectly evaluated by means of particle counting, a technique derived from industrial clean-room technology standards, using airborne particle concentration as an index of microbial contamination. However, the relationship between particle counting and microbiological sampling has rarely been evaluated and demonstrated in operating theatres. The aim of the present study was to determine whether particle counting could predict microbiological contamination of the air in an operating theatre during 95 surgical arthroplasty procedures. This investigation was carried out over a period of three months in 2010 in an orthopedic operating theatre devoted exclusively to prosthetic surgery. During each procedure, the bacterial contamination of the air was determined by means of active sampling; at the same time, airborne particulate contamination was assessed throughout the entire procedure. On considering the total number of surgical operations, the mean value of the total bacterial load in the center of the operating theatre proved to be 35 CFU/m(3); the mean particle count was 4,194,569 no./m(3) for particles of diameter ≥0.5 µm and 13,519 no./m(3) for particles of diameter ≥5 µm. No significant differences emerged between the median values of the airborne microbial load recorded during the two types of procedure monitored. Particulates with a diameter of ≥0.5 µm were detected in statistically higher concentrations (p<0.001) during knee-replacement procedures. By contrast, particulates with a diameter of ≥5 µm displayed a statistically higher concentration during hip-replacement procedures (p<0.05). The results did not reveal any statistically significant correlation between microbial loads and particle counts for either of the particle diameters considered (≥0.5 µm and ≥5 µm). Consequently, microbiological monitoring remains the most suitable method of

  18. Influence of air quality on the composition of microbial pathogens in fresh rainwater.

    PubMed

    Kaushik, Rajni; Balasubramanian, Rajasekhar; de la Cruz, Armah A

    2012-04-01

    In this study, the microbiological quality of fresh rainwater was assessed from 50 rain events under tropical weather conditions for a year. The levels of four major opportunistic waterborne pathogens, namely, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Aeromonas hydrophila, in rainwater samples were quantified by using a robust and sensitive quantitative PCR (qPCR) method. Of the 50 rainwater samples, 25 were found to be positive for at least one pathogen: 21 for E. coli, 16 for P. aeruginosa, 6 for K. pneumoniae, and 1 for A. hydrophila. In addition to the microbiological assessment of rainwater samples, we also studied the influence of prevailing air quality on the microbial quality of rainwater over the sampling period. A significant change in the diversity and relative abundance of the basic microbial indicator organisms in rainwater was observed during a major regional air pollution episode in Southeast Asia due to biomass-burning emissions.

  19. Enzymatic Fuel Cells: Integrating Flow-Through Anode and Air-Breathing Cathode into a Membrane-Less Biofuel Cell Design (Postprint)

    DTIC Science & Technology

    2011-06-01

    AFRL-RX-TY-TP-2011-0081 ENZYMATIC FUEL CELLS: INTEGRATING FLOW- THROUGH ANODE AND AIR-BREATHING CATHODE INTO A MEMBRANE-LESS BIOFUEL CELL...RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 01-JUN-2011 Journal Article (POSTPRINT) 01-JAN-2010 -- 31-JAN-2011 Enzymatic Fuel Cells...unlimited. Ref Public Affairs Case # 88ABW-2011-2228, 14 Apr 11. Document contains color images. One of the key goals of enzymatic biofuel cells

  20. Performance evaluation of low cost microbial fuel cell fabricated using earthen pot with biotic and abiotic cathode.

    PubMed

    Behera, Manaswini; Jana, Partha S; Ghangrekar, M M

    2010-02-01

    An attempt has been made to produce low cost MFC from the commercially available earthen pots in India, without involving any costly membrane. This MFC gave a maximum power output of 16.8 W/m(3) at a Coulombic efficiency (CE) of 31.3% with graphite plate cathode. With stainless steel mesh cathode and KMnO(4) as cathodic electrolyte the power production and CE of 70.48 W/m(3) and 64.5%, respectively, was obtained. The performance of this earthen pot MFC was evaluated with biotic and abiotic cathode. Although, biofilm formation on the cathode is observed to be helpful in enhancing power out put, the thicker biofilm on the cathode showed reduction in power. This MFC demonstrated competitive performance as compared to MFC incorporated with membrane. This low cost MFC, with total production cost of less than 1.0$, as per Indian market, demonstrated its utility as a wastewater treatment and onsite power generation device.

  1. Impacts of Microbial Growth on the Air Quality of the International Space Station

    NASA Technical Reports Server (NTRS)

    Macatangay, Ariel V.; Bruce, Rebekah J.

    2009-01-01

    An understanding of the various sources of non-methane volatile organic compounds (NMVOCs) is one facet to ensuring the habitability of crewed spacecraft. Even though the International Space Station (ISS) atmosphere is relatively well characterized in terms of what is in the atmosphere and approximately how much, linking the majority of these trace contaminants detected to their source is virtually impossible. Albeit a few of can be associated to a single source, the majority of these trace contaminants have their origins from multiple sources. On crewed spacecraft such as ISS, trace contaminants are broadly categorized as either coming from equipment, which includes systems and payloads, or from the metabolic processes of the crew members. Such widely encompassing categories clearly illustrate the difficulty in linking air contaminants to their source(s). It is well known that microbial growth in ISS can flourish if left unchecked. Although processes are in place to limit microbial growth, in reality, microbial growth has pervaded the habitable environment of ISS. This is simply a consequence of having crewed spacecraft, as humans are the largest contributor to the bioload. As with crew members, microbes also have metabolic processes which, in many ways, are comparable to human metabolism. As such, it can be expected that microbial growth can lead to the release of volatile organic compounds into the ISS atmosphere. Given a large enough microbial population, the impact to the air quality of ISS can be potentially large. A survey of the microbiology found in ISS will be presented as well as the possible types of volatile organic compounds that can result from such organisms. This will be correlated to the observations provided by ground-based analysis of ISS atmosphere samples.

  2. Impacts of Microbial Growth on the Air Quality of the International Space Station

    NASA Technical Reports Server (NTRS)

    Macatangay, Ariel V.; Bruce, Rebekah J.

    2010-01-01

    An understanding of the various sources of non-methane volatile organic compounds (NMVOCs) is one facet to ensuring the habitability of crewed spacecraft. Even though the International Space Station (ISS) atmosphere is relatively well characterized in terms of what is in the atmosphere and approximately how much, linking the majority of these trace contaminants detected to their source is virtually impossible. Albeit a few of can be associated to a single source, the majority of these trace contaminants have their origins from multiple sources. On crewed spacecraft such as ISS, trace contaminants are broadly categorized as either coming from equipment, which includes systems and payloads, or from the metabolic processes of the crew members. Such widely encompassing categories clearly illustrate the difficulty in linking air contaminants to their source(s). It is well known that microbial growth in ISS can flourish if left unchecked. Although processes are in place to limit microbial growth, in reality, microbial growth has pervaded the habitable environment of ISS. This is simply a consequence of having crewed spacecraft, as humans are the largest contributor to the bioload. As with crew members, microbes also have metabolic processes which, in many ways, are comparable to human metabolism. As such, it can be expected that microbial growth can lead to the release of volatile organic compounds into the ISS atmosphere. Given a large enough microbial population, the impact to the air quality of ISS can be potentially large. A survey of the microbiology found in ISS will be presented as well as the possible types of volatile organic compounds that can result from such organisms. This will be correlated to the observations provided by ground-based analysis of ISS atmosphere samples

  3. Air sampling methods to evaluate microbial contamination in operating theatres: results of a comparative study in an orthopaedics department.

    PubMed

    Napoli, C; Tafuri, S; Montenegro, L; Cassano, M; Notarnicola, A; Lattarulo, S; Montagna, M T; Moretti, B

    2012-02-01

    To evaluate the level of microbial contamination of air in operating theatres using active [i.e. surface air system (SAS)] and passive [i.e. index of microbial air contamination (IMA) and nitrocellulose membranes positioned near the wound] sampling systems. Sampling was performed between January 2010 and January 2011 in the operating theatre of the orthopaedics department in a university hospital in Southern Italy. During surgery, the mean bacterial loads recorded were 2232.9 colony-forming units (cfu)/m(2)/h with the IMA method, 123.2 cfu/m(3) with the SAS method and 2768.2 cfu/m(2)/h with the nitrocellulose membranes. Correlation was found between the results of the three methods. Staphylococcus aureus was detected in 12 of 60 operations (20%) with the membranes, five (8.3%) operations with the SAS method, and three operations (5%) with the IMA method. Use of nitrocellulose membranes placed near a wound is a valid method for measuring the microbial contamination of air. This method was more sensitive than the IMA method and was not subject to any calibration bias, unlike active air monitoring systems. Copyright © 2011 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  4. Batteryless, wireless sensor powered by a sediment microbial fuel cell.

    PubMed

    Donovan, Conrad; Dewan, Alim; Heo, Deukhyoun; Beyenal, Haluk

    2008-11-15

    Sediment microbial fuel cells (SMFCs) are considered to be an alternative renewable power source for remote monitoring. There are two main challenges to using SMFCs as power sources: 1) a SMFC produces a low potential at which most sensor electronics do not operate, and 2) a SMFC cannot provide continuous power, so energy from the SMFC must be stored and then used to repower sensor electronics intermittently. In this study, we developed a SMFC and a power management system (PMS) to power a batteryless, wireless sensor. A SMFC operating with a microbial anode and cathode, located in the Palouse River, Pullman, Washington, U.S.A., was used to demonstrate the utility of the developed system. The designed PMS stored microbial energy and then started powering the wireless sensor when the SMFC potential reached 320 mV. It continued powering until the SMFC potential dropped below 52 mV. The system was repowered when the SMFC potential increased to 320 mV, and this repowering continued as long as microbial reactions continued. We demonstrated that a microbial fuel cell with a microbial anode and cathode can be used as an effective renewable power source for remote monitoring using custom-designed electronics.

  5. Photoemission experiments of a large area scandate dispenser cathode

    NASA Astrophysics Data System (ADS)

    Zhang, Huang; Liu, Xing-guang; Chen, Yi; Chen, De-biao; Jiang, Xiao-guo; Yang, An-min; Xia, Lian-sheng; Zhang, Kai-zhi; Shi, Jin-shui; Zhang, Lin-wen

    2010-09-01

    A 100-mm-diameter scandate dispenser cathode was tested as a photocathode with a 10 ns Nd:YAG laser (266 nm) on an injector test stand for linear induction accelerators. This thermionic dispenser cathode worked at temperatures ranging from room temperature to 930 °C (below or near the thermionic emission threshold) while the vacuum was better than 4×10 -7 Torr. The laser pulse was synchronized with a 120 ns diode voltage pulse stably and they were in single pulse mode. Emission currents were measured by a Faraday cup. The maximum peak current collected at the anode was about 100 A. The maximum quantum efficiency measured at low laser power was 2.4×10 -4. Poisoning effect due to residual gas was obvious and uninterrupted heating was needed to keep cathode's emission capability. The cathode was exposed to air one time between experiments and recovered after being reconditioned. Photoemission uniformity of the cathode was also explored by changing the laser spot's position.

  6. Sustainable Hypersaline Microbial Fuel Cells: Inexpensive Recyclable Polymer Supports for Carbon Nanotube Conductive Paint Anodes.

    PubMed

    Grattieri, Matteo; Shivel, Nelson D; Sifat, Iram; Bestetti, Massimiliano; Minteer, Shelley D

    2017-05-09

    Microbial fuel cells are an emerging technology for wastewater treatment, but to be commercially viable and sustainable, the electrode materials must be inexpensive, recyclable, and reliable. In this study, recyclable polymeric supports were explored for the development of anode electrodes to be applied in single-chamber microbial fuel cells operated in field under hypersaline conditions. The support was covered with a carbon nanotube (CNT) based conductive paint, and biofilms were able to colonize the electrodes. The single-chamber microbial fuel cells with Pt-free cathodes delivered a reproducible power output after 15 days of operation to achieve 12±1 mW m -2 at a current density of 69±7 mA m -2 . The decrease of the performance in long-term experiments was mostly related to inorganic precipitates on the cathode electrode and did not affect the performance of the anode, as shown by experiments in which the cathode was replaced and the fuel cell performance was regenerated. The results of these studies show the feasibility of polymeric supports coated with CNT-based paint for microbial fuel cell applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Effect of high donor number solvent and cathode morphology on interfacial processes in Li-air batteries

    NASA Astrophysics Data System (ADS)

    Kislenko, S. A.

    2018-01-01

    The work is focused on the investigation of the effect of solvent and carbon cathode morphology on the performance of Li-air batteries. Molecular dynamics simulation was used to explore the interfacial behavior of the main reactants (O2 and Li+) of the oxygen reduction reaction in high donor number solvent dimethyl sulfoxide (DMSO) at the following carbon surfaces: graphene plane, graphene edge, nanotube. It was shown that the adsorption barrier of O2 molecules decreases in the order graphene plane > nanotube > graphene edge, leading to the fastest adsorption kinetics on graphene edges. Strong solvation of Li+ in DMSO prevents ions adsorption on defect-free graphene planes and nanotubes, which is qualitatively different from low donor number solvents, such as acetonitrile. It can be concluded from these results, that nucleation and growth of discharge products in DMSO is shifted from the surface towards the solvent bulk that, in turn, leads to capacity increase of Li-air batteries.

  8. Microbial Contamination on Used Surgical Masks among Hospital Personnel and Microbial Air Quality in their Working Wards: A Hospital in Bangkok

    PubMed Central

    Luksamijarulkul, Pipat; Aiempradit, Natkitta; Vatanasomboon, Pisit

    2014-01-01

    Objective To assess the relationship of bacterial and fungal contamination on used surgical masks worn by the hospital personnel and microbial air quality in their working wards. Methods This is a cross-sectional study of 230 used surgical masks collected from 214 hospital personnel, and 215 indoor air samples collected from their working wards to culture for bacterial and fungal counts. This study was carried out at the hospital in Bangkok. Group or genus of isolated bacteria and fungi were preliminarily identified by Gram’s stain and lacto-phenol cotton blue. Data were analyzed using paired t-test and Pearson’s correlation coefficient at the significant level of p<0.050. Results Means and standard deviation of bacterial and fungal contamination on inside area of the used masks were 47 ± 56 and 15 ± 9 cfu/ml/piece, and on outside area were 166 ± 199 and 34 ± 18 cfu/ml/piece, respectively, p<0.001. The bacterial and fungal contamination on used masks from hospital personnel working in the male and female medical wards and out-patient department, as well as the bacterial and fungal counts of the indoor air sample collected from the same area were relatively higher than the other wards. The predominant isolated bacteria and fungi contaminated on inside and outside areas of the used masks and air samples were similar (Staphylococcus spp. and Aspergillus spp.; respectively). For its relationship, results found that bacterial and fungal counts in air samples showed significantly positive correlation with the bacterial contamination load on outside area of the used masks, r=0.16, p=0.018 and r=0.21, p=0.003, respectively. Conclusion High bacterial contamination on outside area of the used masks was demonstrated, and it showed a significant correlation with microbial air quality of working wards. PMID:25337311

  9. Microbial Contamination on Used Surgical Masks among Hospital Personnel and Microbial Air Quality in their Working Wards: A Hospital in Bangkok.

    PubMed

    Luksamijarulkul, Pipat; Aiempradit, Natkitta; Vatanasomboon, Pisit

    2014-09-01

    To assess the relationship of bacterial and fungal contamination on used surgical masks worn by the hospital personnel and microbial air quality in their working wards. This is a cross-sectional study of 230 used surgical masks collected from 214 hospital personnel, and 215 indoor air samples collected from their working wards to culture for bacterial and fungal counts. This study was carried out at the hospital in Bangkok. Group or genus of isolated bacteria and fungi were preliminarily identified by Gram's stain and lacto-phenol cotton blue. Data were analyzed using paired t-test and Pearson's correlation coefficient at the significant level of p<0.050. Means and standard deviation of bacterial and fungal contamination on inside area of the used masks were 47 ± 56 and 15 ± 9 cfu/ml/piece, and on outside area were 166 ± 199 and 34 ± 18 cfu/ml/piece, respectively, p<0.001. The bacterial and fungal contamination on used masks from hospital personnel working in the male and female medical wards and out-patient department, as well as the bacterial and fungal counts of the indoor air sample collected from the same area were relatively higher than the other wards. The predominant isolated bacteria and fungi contaminated on inside and outside areas of the used masks and air samples were similar (Staphylococcus spp. and Aspergillus spp.; respectively). For its relationship, results found that bacterial and fungal counts in air samples showed significantly positive correlation with the bacterial contamination load on outside area of the used masks, r=0.16, p=0.018 and r=0.21, p=0.003, respectively. High bacterial contamination on outside area of the used masks was demonstrated, and it showed a significant correlation with microbial air quality of working wards.

  10. Air-cooled, hydrogen-air fuel cell

    NASA Technical Reports Server (NTRS)

    Shelekhin, Alexander B. (Inventor); Bushnell, Calvin L. (Inventor); Pien, Michael S. (Inventor)

    1999-01-01

    An air-cooled, hydrogen-air solid polymer electrolyte (SPE) fuel cell with a membrane electrode assembly operatively associated with a fluid flow plate having at least one plate cooling channel extending through the plate and at least one air distribution hole extending from a surface of the cathode flow field into the plate cooling channel.

  11. Identification of Microbial Communities in Open and Closed Circuit Bioelectrochemical MBRs by High-Throughput 454 Pyrosequencing

    PubMed Central

    Huang, Jian; Wang, Zhiwei; Zhu, Chaowei; Ma, Jinxing; Zhang, Xingran; Wu, Zhichao

    2014-01-01

    Two bioelectrochemical membrane bioreactors (MBRs) developed by integrating microbial fuel cell and MBR technology were operated under closed-circuit and open-circuit modes, and high-throughput 454 pyrosequencing was used to investigate the effects of the power generation on the microbial community of bio-anode and bio-cathode. Microbes on the anode under open-circuit operation (AO) were enriched and highly diverse when compared to those on the anode under closed-circuit operation (AC). However, among the cathodes the closed-circuit mode (CC) had richer and more diverse microbial community compared to the cathode under open-circuit mode (CO). On the anodes AO and AC, Proteobacteria and Bacteroidetes were the dominant phyla, while Firmicutes was enriched only on AC. Deltaproteobacteria affiliated to Proteobacteria were also more abundant on AC than AO. Furthermore, the relative abundance of Desulfuromonas, which are well-known electrogenic bacteria, were much higher on AC (10.2%) when compared to AO (0.11%), indicating that closed-circuit operation was more conducive for the growth of electrogenic bacteria on the anodes. On the cathodes, Protebacteria was robust on CC while Bacteroidetes was more abundant on CO. Rhodobacter and Hydrogenophaga were also enriched on CC than CO, suggesting that these genera play a role in electron transfer from the cathode surface to the terminal electron acceptors in the bioelectrochemical MBR under closed-circuit operation. PMID:24705450

  12. Freestanding and flexible graphene papers as bioelectrochemical cathode for selective and efficient CO2 conversion.

    PubMed

    Aryal, Nabin; Halder, Arnab; Zhang, Minwei; Whelan, Patrick R; Tremblay, Pier-Luc; Chi, Qijin; Zhang, Tian

    2017-08-22

    During microbial electrosynthesis (MES) driven CO 2 reduction, cathode plays a vital role by donating electrons to microbe. Here, we exploited the advantage of reduced graphene oxide (RGO) paper as novel cathode material to enhance electron transfer between the cathode and microbe, which in turn facilitated CO 2 reduction. The acetate production rate of Sporomusa ovata-driven MES reactors was 168.5 ± 22.4 mmol m -2 d -1 with RGO paper cathodes poised at -690 mV versus standard hydrogen electrode. This rate was approximately 8 fold faster than for carbon paper electrodes of the same dimension. The current density with RGO paper cathodes of 2580 ± 540 mA m -2 was increased 7 fold compared to carbon paper cathodes. This also corresponded to a better cathodic current response on their cyclic voltammetric curves. The coulombic efficiency for the electrons conversion into acetate was 90.7 ± 9.3% with RGO paper cathodes and 83.8 ± 4.2% with carbon paper cathodes, respectively. Furthermore, more intensive cell attachment was observed on RGO paper electrodes than on carbon paper electrodes with confocal laser scanning microscopy and scanning electron microscopy. These results highlight the potential of RGO paper as a promising cathode for MES from CO 2 .

  13. [Restoration of microbial ammonia oxidizers in air-dried forest soils upon wetting].

    PubMed

    Zhou, Xue; Huang, Rong; Song, Ge; Pan, Xianzhang; Jia, Zhongjun

    2014-11-04

    This study was aimed to investigate the abundance and community shift of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in air-dried forest soils in response to water addition, to explore the applicability of air-dried soil for microbial ecology study, and to elucidate whether AOA within the marine group 1. 1a dominate ammonia oxidizers communities in the acidic forest soils in China. Soil samples were collected from 10 forest sites of the China Ecosystem Research Network (CERN) and kept under air-drying conditions in 2010. In 2013 the air-dried soil samples were adjusted to 60% of soil maximum water holding capacity for a 28-day incubation at 28 degrees C in darkness. DGGE fingerprinting, clone library construction, pyrosequencing and quantitative PCR of amoA genes were performed to assess community change of ammonia oxidizers in air-dried and re-wetted soils. After incubation for 28 days, the abundance of bacteria and archaea increased significantly, up to 3,230 and 568 times, respectively. AOA increased significantly in 8 samples, and AOB increased significantly in 5 of 10 samples. However, pyrosequencing of amoA genes reveals insignificant changes in composition of AOA and AOB communities. Phylogenetic analysis of amoA genes indicates that archaeal ammonia oxidizers were predominated by AOA within the soil group 1. 1b lineage, while the Nitrosospira-like AOB dominate bacteria ammonia oxidizer communities. There was a significantly positive correlation between AOA/AOB ratio and total nitrogen (r2 = 0.54, P < 0.05), implying that soil ammonia oxidation might be dominated by AOA in association with ammonium released from soil mineralization. Phylogenetic analysis suggest that AOA members within the soil group 1. 1b lineage were not restricted to non-acidic soils as previously thought. The abundance rather than composition of AOA and AOB changed in response to water addition. This indicates that air-dried soil could be of help for microbial biogeography study.

  14. Cathode architectures for alkali metal / oxygen batteries

    DOEpatents

    Visco, Steven J; Nimon, Vitaliy; De Jonghe, Lutgard C; Volfkovich, Yury; Bograchev, Daniil

    2015-01-13

    Electrochemical energy storage devices, such as alkali metal-oxygen battery cells (e.g., non-aqueous lithium-air cells), have a cathode architecture with a porous structure and pore composition that is tailored to improve cell performance, especially as it pertains to one or more of the discharge/charge rate, cycle life, and delivered ampere-hour capacity. A porous cathode architecture having a pore volume that is derived from pores of varying radii wherein the pore size distribution is tailored as a function of the architecture thickness is one way to achieve one or more of the aforementioned cell performance improvements.

  15. High speed municipal sewage treatment in microbial fuel cell integrated with anaerobic membrane filtration system.

    PubMed

    Lee, Y; Oa, S W

    2014-01-01

    A cylindrical two chambered microbial fuel cell (MFC) integrated with an anaerobic membrane filter was designed and constructed to evaluate bioelectricity generation and removal efficiency of organic substrate (glucose or domestic wastewater) depending on organic loading rates (OLRs). The MFC was continuously operated with OLRs 3.75, 5.0, 6.25, and 9.38 kg chemical oxygen demand (COD)/(m(3)·d) using glucose as a substrate, and the cathode chamber was maintained at 5-7 mg/L of dissolved oxygen. The optimal OLR was found to be 6.25 kgCOD/(m(3)·d) (hydraulic retention time (HRT) 1.9 h), and the corresponding voltage and power density averaged during the operation were 0.15 V and 13.6 mW/m(3). With OLR 6.25 kgCOD/(m(3)·d) using domestic wastewater as a substrate, the voltage and power reached to 0.13 V and 91 mW/m(3) in the air cathode system. Even though a relatively short HRT of 1.9 h was applied, stable effluent could be obtained by the membrane filtration system and the following air purging. In addition, the short HRT would provide economic benefit in terms of reduction of construction and operating costs compared with a conventional aerobic treatment process.

  16. Air breathing direct methanol fuel cell

    DOEpatents

    Ren, Xiaoming; Gottesfeld, Shimshon

    2002-01-01

    An air breathing direct methanol fuel cell is provided with a membrane electrode assembly, a conductive anode assembly that is permeable to air and directly open to atmospheric air, and a conductive cathode assembly that is permeable to methanol and directly contacting a liquid methanol source. Water loss from the cell is minimized by making the conductive cathode assembly hydrophobic and the conductive anode assembly hydrophilic.

  17. Scale-up of phosphate remobilization from sewage sludge in a microbial fuel cell.

    PubMed

    Happe, Manuel; Sugnaux, Marc; Cachelin, Christian Pierre; Stauffer, Marc; Zufferey, Géraldine; Kahoun, Thomas; Salamin, Paul-André; Egli, Thomas; Comninellis, Christos; Grogg, Alain-François; Fischer, Fabian

    2016-01-01

    Phosphate remobilization from digested sewage sludge containing iron phosphate was scaled-up in a microbial fuel cell (MFC). A 3litre triple chambered MFC was constructed. This reactor was operated as a microbial fuel cell and later as a microbial electrolysis cell to accelerate cathodic phosphate remobilization. Applying an additional voltage and exceeding native MFC power accelerated chemical base formation and the related phosphate remobilization rate. The electrolysis approach was extended using a platinum-RVC cathode. The pH rose to 12.6 and phosphate was recovered by 67% in 26h. This was significantly faster than using microbial fuel cell conditions. Shrinking core modelling particle fluid kinetics showed that the reaction resistance has to move inside the sewage sludge particle for considerable rate enhancement. Remobilized phosphate was subsequently precipitated as struvite and inductively coupled plasma mass spectrometry indicated low levels of cadmium, lead, and other metals as required by law for recycling fertilizers. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Li-air batteries: Decouple to stabilize

    NASA Astrophysics Data System (ADS)

    Xu, Ji-Jing; Zhang, Xin-Bo

    2017-09-01

    The utilization of porous carbon cathodes in lithium-air batteries is hindered by their severe decomposition during battery cycling. Now, dual redox mediators are shown to decouple the complex electrochemical reactions at the cathode, avoiding cathode passivation and decomposition.

  19. Enhancement of the microbial community biomass and diversity during air sparging bioremediation of a soil highly contaminated with kerosene and BTEX.

    PubMed

    Kabelitz, Nadja; Machackova, Jirina; Imfeld, Gwenaël; Brennerova, Maria; Pieper, Dietmar H; Heipieper, Hermann J; Junca, Howard

    2009-03-01

    In order to obtain insights in complexity shifts taking place in natural microbial communities under strong selective pressure, soils from a former air force base in the Czech Republic, highly contaminated with jet fuel and at different stages of a bioremediation air sparging treatment, were analyzed. By tracking phospholipid fatty acids and 16S rRNA genes, a detailed monitoring of the changes in quantities and composition of the microbial communities developed at different stages of the bioventing treatment progress was performed. Depending on the length of the air sparging treatment that led to a significant reduction in the contamination level, we observed a clear shift in the soil microbial community being dominated by Pseudomonads under the harsh conditions of high aromatic contamination to a status of low aromatic concentrations, increased biomass content, and a complex composition with diverse bacterial taxonomical branches.

  20. Occurrence and quantitative microbial risk assessment of Cryptosporidium and Giardia in soil and air samples.

    PubMed

    Balderrama-Carmona, Ana Paola; Gortáres-Moroyoqui, Pablo; Álvarez-Valencia, Luis Humberto; Castro-Espinoza, Luciano; Mondaca-Fernández, Iram; Balderas-Cortés, José de Jesús; Chaidez-Quiroz, Cristóbal; Meza-Montenegro, María Mercedes

    2014-09-01

    Cryptosporidium oocysts and Giardia cysts can be transmitted by the fecal-oral route and may cause gastrointestinal parasitic zoonoses. These zoonoses are common in rural zones due to the parasites being harbored in fecally contaminated soil. This study assessed the risk of illness (giardiasis and cryptosporidiosis) from inhaling and/or ingesting soil and/or airborne dust in Potam, Mexico. To assess the risk of infection, Quantitative Microbial Risk Assessment (QMRA) was employed, with the following steps: (1) hazard identification, (2) hazard exposure, (3) dose-response, and (4) risk characterization. Cryptosporidium oocysts and Giardia cysts were observed in 52% and 57%, respectively, of total soil samples (n=21), and in 60% and 80%, respectively, of air samples (n=12). The calculated annual risks were higher than 9.9 × 10(-1) for both parasites in both types of sample. Soil and air inhalation and/or ingestion are important vehicles for these parasites. To our knowledge, the results obtained in the present study represent the first QMRAs for cryptosporidiosis and giardiasis due to soil and air inhalation/ingestion in Mexico. In addition, this is the first evidence of the microbial air quality around these parasites in rural zones. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Impact of Fe(III) as an effective electron-shuttle mediator for enhanced Cr(VI) reduction in microbial fuel cells: Reduction of diffusional resistances and cathode overpotentials.

    PubMed

    Wang, Qiang; Huang, Liping; Pan, Yuzhen; Quan, Xie; Li Puma, Gianluca

    2017-01-05

    The role of Fe(III) was investigated as an electron-shuttle mediator to enhance the reduction rate of the toxic heavy metal hexavalent chromium (Cr(VI)) in wastewaters, using microbial fuel cells (MFCs). The direct reduction of chromate (CrO 4 - ) and dichromate (Cr 2 O 7 2- ) anions in MFCs was hampered by the electrical repulsion between the negatively charged cathode and Cr(VI) functional groups. In contrast, in the presence of Fe(III), the conversion of Cr(VI) and the cathodic coulombic efficiency in the MFCs were 65.6% and 81.7%, respectively, 1.6 times and 1.4 folds as those recorded in the absence of Fe(III). Multiple analytical approaches, including linear sweep voltammetry, Tafel plot, cyclic voltammetry, electrochemical impedance spectroscopy and kinetic calculations demonstrated that the complete reduction of Cr(VI) occurred through an indirect mechanism mediated by Fe(III). The direct reduction of Cr(VI) with cathode electrons in the presence of Fe(III) was insignificant. Fe(III) played a critical role in decreasing both the diffusional resistance of Cr(VI) species and the overpotential for Cr(VI) reduction. This study demonstrated that the reduction of Cr(VI) in MFCs was effective in the presence of Fe(III), providing an alternative and environmentally benign approach for efficient remediation of Cr(VI) contaminated sites with simultaneous production of renewable energy. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Traffic flow and microbial air contamination in operating rooms at a major teaching hospital in Ghana.

    PubMed

    Stauning, M T; Bediako-Bowan, A; Andersen, L P; Opintan, J A; Labi, A-K; Kurtzhals, J A L; Bjerrum, S

    2018-07-01

    Current literature examining the relationship between door-opening rate, number of people present, and microbial air contamination in the operating room is limited. Studies are especially needed from low- and middle-income countries, where the risk of surgical site infections is high. To assess microbial air contamination in operating rooms at a Ghanaian teaching hospital and the association with door-openings and number of people present. Moreover, we aimed to document reasons for door-opening. We conducted active air-sampling using an MAS 100 ® portable impactor during 124 clean or clean-contaminated elective surgical procedures. The number of people present, door-opening rate and the reasons for each door-opening were recorded by direct observation using pretested structured observation forms. During surgery, the mean number of colony-forming units (cfu) was 328 cfu/m 3 air, and 429 (84%) of 510 samples exceeded a recommended level of 180 cfu/m 3 . Of 6717 door-openings recorded, 77% were considered unnecessary. Levels of cfu/m 3 were strongly correlated with the number of people present (P = 0.001) and with the number of door-openings/h (P = 0.02). In empty operating rooms, the mean cfu count was 39 cfu/m 3 after 1 h of uninterrupted ventilation and 52 (51%) of 102 samples exceeded a recommended level of 35 cfu/m 3 . The study revealed high values of intraoperative airborne cfu exceeding recommended levels. Minimizing the number of door-openings and people present during surgery could be an effective strategy to reduce microbial air contamination in low- and middle-income settings. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  3. Current Progresses of Midass: Microbial Detection in Air System for Space

    NASA Astrophysics Data System (ADS)

    Abaibou, Hafid; Lasseur, Christophe; Mabilat, Claude; Storrs-Mabilat, Michele; Guy, Michel; Raffestin, Stephanie; Sole Bosquet, Jaume

    For the long term manned missions, microbial contamination is a major risk for crew members and hardware. This risk has first been documented by Russian scientists then by other organizations as a consequence of the contamination of metabolic consumables (water, air), and also the hardware degradation. Rapid molecular biology techniques offer an attractive alternative to traditional culture-based methods. They allow fast time to results for contamination detection and quick implementation of appropriate corrective action when required. However, to date, there are no such available system due to the technical challenges required to meet the sensitivity and specificity needs of the test and the requirement for full automation, from sampling to results interpretation. In response to this, over the last decade, the European Space Agency (ESA) and bioMérieux initiated a co-development of MIDASS, the world’s first fully automated system for the monitoring of the environmental microbial load in confined spaces, including clean rooms and hospital wards. The system is based on molecular technologies (sample preparation/amplification/detection) and enables rapid and simple determination of the microbiological contamination level in less than 3 hours. It relies on NASBA-amplification for the detection of selected micro-organisms (indicators or pathogens) at determined risk-levels (200 and 1 CFU /m3 air, respectively). Successful progresses were recently made for the space-application workpackage of this project: a lab-on-a-card design for air-testing in a first scope was endorsed by a successful ESA Preliminary Design Review, paving the way to spatialization steps (phases C and D). Data will be presented with regards to system design and biological performances.

  4. Electricity and biomass production in a bacteria-Chlorella based microbial fuel cell treating wastewater

    NASA Astrophysics Data System (ADS)

    Commault, Audrey S.; Laczka, Olivier; Siboni, Nachshon; Tamburic, Bojan; Crosswell, Joseph R.; Seymour, Justin R.; Ralph, Peter J.

    2017-07-01

    The chlorophyte microalga Chlorella vulgaris has been exploited within bioindustrial settings to treat wastewater and produce oxygen at the cathode of microbial fuel cells (MFCs), thereby accumulating algal biomass and producing electricity. We aimed to couple these capacities by growing C. vulgaris at the cathode of MFCs in wastewater previously treated by anodic bacteria. The bioelectrochemical performance of the MFCs was investigated with different catholytes including phosphate buffer and anode effluent, either in the presence or absence of C. vulgaris. The power output fluctuated diurnally in the presence of the alga. The maximum power when C. vulgaris was present reached 34.2 ± 10.0 mW m-2, double that observed without the alga (15.6 ± 9.7 mW m-2), with a relaxation of 0.19 gL-1 d-1 chemical oxygen demand and 5 mg L-1 d-1 ammonium also removed. The microbial community associated with the algal biofilm included nitrogen-fixing (Rhizobiaceae), denitrifying (Pseudomonas stutzeri and Thauera sp., from Pseudomonadales and Rhodocyclales orders, respectively), and nitrate-reducing bacteria (Rheinheimera sp. from the Alteromonadales), all of which likely contributed to nitrogen cycling processes at the cathode. This paper highlights the importance of coupling microbial community screening to electrochemical and chemical analyses to better understand the processes involved in photo-cathode MFCs.

  5. Estimation of the temporary service life of DC arc plasmatron cathode

    NASA Astrophysics Data System (ADS)

    Kulygin, V. M.; Pereslavtsev, A. V.; Tresvyatskii, S. S.

    2017-09-01

    The service life of the cathode of a DC arc plasmatron continuously working with tubular electrodes that operate in the air has been considered using the semi-phenomenological approach. The thermal emission, that ensures the necessary flow of electrons, and the evaporation of the cathode material, which determines its erosion, have been taken as the basic physical phenomena that constitute the workflow. The relationships that enable the estimation of the cathode's operating time have been obtained using the known regularities of these phenomena and experimental data available in the literature. The resulting evaluations coincide satisfactorily with the endurance test results.

  6. Determination of effects of turbulence flow in a cathode environment on electricity generation using a tidal mud-based cylindrical-type sediment microbial fuel cell.

    PubMed

    An, Junyeong; Lee, Soo-Jin; Ng, How Yong; Chang, In Seop

    2010-12-01

    We examined the possibility of harvesting electricity from the surface of a tidal mud flat using a cylindrical-type sediment microbial fuel cell (SMFC), a marine mud battery (MMB), which can be applied in a sea environment where the ebb and flow occur due to tidal difference. In addition, we indirectly investigated the influence of ebb and flow in a lab, using aeration, argon gassing, and by agitating the cathodic solution. The MMBs consisted of cylindrical acrylic compartments containing a nylon membrane, an anode, and a cathode in a single body. The MMBs were stuck vertically into an artificial tidal mud flat such that the anode electrode was in direct contact with the tidal mud surface. As a result, the maximum current and power density generated were 35 mA/m(2) and 9 mW/m(2), respectively, thus verifying that it is possible to harvest electricity from the surface of a tidal mud flat using an MMB without burying the anode electrode in the tidal mud. Furthermore, the results of tests using an artificial turbulence flow showed the flow induced by the tidal ebb and flow could allow the performance of MMBs to be enhanced. Copyright © 2010 Elsevier Ltd. All rights reserved.

  7. Increased electrical output when a bacterial ABTS oxidizer is used in a microbial fuel cell

    USDA-ARS?s Scientific Manuscript database

    Microbial fuel cells (MFCs) are a technology that provides electrical energy from the microbial oxidation of organic compounds. Most MFCs use oxygen as the oxidant in the cathode chamber. The present study examined the formation in culture of an unidentified bacterial oxidant and investigated the ...

  8. Using elastin protein to develop highly efficient air cathodes for lithium-O2 batteries

    NASA Astrophysics Data System (ADS)

    Guo, Guilue; Yao, Xin; Ang, Huixiang; Tan, Huiteng; Zhang, Yu; Guo, Yuanyuan; Fong, Eileen; Yan, Qingyu

    2016-01-01

    Transition metal-nitrogen/carbon (M-N/C, M = Fe, Co) catalysts are synthesized using environmentally friendly histidine-tag-rich elastin protein beads, metal sulfate and water soluble carbon nanotubes followed by post-annealing and acid leaching processes. The obtained catalysts are used as cathode materials in lithium-O2 batteries. It has been discovered that during discharge, Li2O2 nanoparticles first nucleate and grow around the bead-decorated CNT regions (M-N/C centres) and coat on the catalysts at a high degree of discharge. The Fe-N/C catalyst-based cathodes deliver a capacity of 12 441 mAh g-1 at a current density of 100 mA g-1. When they were cycled at a limited capacity of 800 mAh g-1 at current densities of 200 or 400 mA g-1, these cathodes showed stable charge voltages of ˜3.65 or 3.90 V, corresponding to energy efficiencies of ˜71.2 or 65.1%, respectively. These results are considerably superior to those of the cathodes based on bare annealed CNTs, which prove that the Fe-N/C catalysts developed here are promising for use in non-aqueous lithium-O2 battery cathodes.

  9. High Capacity Cathode Materials for Next Generation Energy Storage

    NASA Astrophysics Data System (ADS)

    Papandrea, Benjamin John

    Energy storage devices are of increasing importance for applications in mobile electronics, hybrid electric vehicles, and can also play a critical role in renewable energy harvesting, conversion and storage. Since its commercial inception in the 1990's, the lithium-ion battery represents the dominant energy storage technology for mobile power supply today. However, the total capacity of lithium-ion batteries is largely limited by the theoretical capacities of the cathode materials such as LiCoO2 (272 mAh g-1), and LiFePO4 (170 mAh g-1), and cannot satisfy the increasing consumer demand, thus new cathode materials with higher capacities must be explored. Two of the most promising cathode materials with significantly larger theoretical capacities are sulfur (1675 mAh g-1) and air, specifically the oxygen (3840 mAh g-1). However, the usage of either of these cathodic materials is plagued with numerous issues that must be overcome before their commercialization. In the first part of my dissertation, we investigated the usage of a three-dimensional graphene membrane for a high energy density lithium-air (Li-Air) battery in ambient condition. One of the issues with Li-Air batteries is the many side reaction that can occur during discharge in ambient condition, especially with water vapor. Using a hydrophobic tortuous three-dimensional graphene membrane we are able to inhibit the diffusion of water vapor and create a lithium-air battery that cycles over 2000 times with a capacity limited at 140 mAh g-1, over 100 cycles with a capacity limited at 1425 mAh g-1, and over 20 cycles at the high capacity of 5700 mAh g-1. In the second part of my dissertation, we investigate the usage of a three-dimensional graphene aerogel to maximize the loading of sulfur to create a freestanding electrode with high capacity for a lithium-sulfur (Li-S) battery. We demonstrated that our three-dimensional graphene aerogel could sustain a loading of 95% by weight, and we achieved a capacity of

  10. Note: Measurement of the cathode layer thickness in glow discharges with a Langmuir probe

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Hou, Xinyu; Zou, Xiaobing; Luo, Haiyun; Wang, Xinxin

    2018-06-01

    A method using a Langmuir probe to determine the thickness of the cathode layer for a glow discharge is developed. The method is based on the phenomenon that the curve of the voltage-current characteristics changes in shape as the Langmuir probe moves from the positive column into the cathode layer. The method was used to measure the thicknesses of the cathode layer in the normal glow discharges of argon and air with the cathodes made from stainless steel and aluminum. The results are in good agreement with those given in a book of gas discharge.

  11. Microbial air contamination in indoor environment of a university library.

    PubMed

    Kalwasińska, Agnieszka; Burkowska, Aleksandra; Wilk, Iwona

    2012-01-01

    The present study was aimed at evaluating the number of bacteria and mould fungi in the indoor and outdoor environment of Toruń University Library. The sampling sites were located in the rooms serving the functions typical of libraries (i.e. in the Main Reading Room, Current Periodicals Reading Room, Collections Conservation Laboratory, Old Prints Storeroom, in rooms serving other (non-library) functions (i.e. main hall, cafeteria, and toilet) as well as outside the library building. The analyses reveal that the concentrations of bacterial as well as fungal aerosols estimated with the use of the impaction method ranged between 10(1)-10(3) CFU·m(-3), which corresponds to the concentrations normally observed in areas of this kind. Evaluation of the hygienic condition of the studied areas was based on the criteria for microbiological cleanliness in interiors submitted by the European Commission in 1993. According to this classification, the air was considered to be heavily or moderately contaminated with bacteria, while the air contamination with mould fungi was described as low or moderate. The air in the Old Prints Storeroom was considered the least contaminated with microbial aerosol.

  12. Fully reversible current driven by a dual marine photosynthetic microbial community.

    PubMed

    Darus, Libertus; Lu, Yang; Ledezma, Pablo; Keller, Jürg; Freguia, Stefano

    2015-11-01

    The electrochemical activity of two seawater microbial consortia were investigated in three-electrode bioelectrochemical cells. Two seawater inocula - from the Sunshine Coast (SC) and Gold Coast (GC) shores of Australia - were enriched at +0.6 V vs. SHE using 12/12 h day/night cycles. After re-inoculation, the SC consortium developed a fully-reversible cathodic/anodic current, with a max. of -62 mA m(-2) during the day and +110 mA m(-2) at night, while the GC exhibited negligible daytime output but +98 mA m(-2) at night. Community analysis revealed that both enrichments were dominated by cyanobacteria, indicating their potential as biocatalysts for indirect light conversion to electricity. Moreover, the presence of γ-proteobacterium Congregibacter in SC biofilm was likely related to the cathodic reductive current, indicating its effectiveness at catalysing cathodic oxygen reduction at a surprisingly high potential. For the first time a correlation between a dual microbial community and fully reversible current is reported. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Investigation of microbial community isolated from indoor artworks and air environment: identification, biodegradative abilities, and DNA typing.

    PubMed

    Pangallo, Domenico; Chovanová, Katarina; Simonovicová, Alexandra; Ferianc, Peter

    2009-03-01

    This study deals with establishing the characteristics of a microbial community isolated from indoor artworks and the surrounding air environment. It is one of the few studies on microbial degradation of indoor artworks. It shows the potential biodegradative risk that can occur if artworks are not exhibited and conserved in an appropriate environment. The microbial community isolated from the indoor artworks and air environment was examined by cultural and molecular methods. Different plate assays were used to screen the biodegradative activity of the isolated microflora: Remazol Brilliant Blue R, phenol red, and Azure B for the ligninolytic properties; Ostazin brilliant red H-3B for cellulose degradation; CaCO3 glucose agar for solubilization activity; and B4 agar for biomineralization. To type the bacterial and fungal isolates, 2 PCR methods, repetitive extragenic palindromes (REP) and random amplified microsatellite polymorphisms (RAMP) were used. The art objects were principally colonized by fungi. The most commonly isolated strains were represented by hyphomycetes of the genera Penicillium, Aspergillus, Cladosporium, and Chaetomium. Members of these genera showed intensive biodegradation activity, both on wood and on stone. Bacteria were predominant in the air, exhibiting complex communities, both in the air and on the artworks. The most frequently isolated genera were Bacillus and Staphylococcus with extensive biodegradation abilities. REP-PCR revealed high variability within strains belonging to the same genus. RAMP is a new PCR-based method, used in this research for the first time to cluster the microfilamentous fungi and to characterize and select especially Penicillium and Aspergillus strains, which were isolated in a large number.

  14. Textile Inspired Lithium-Oxygen Battery Cathode with Decoupled Oxygen and Electrolyte Pathways.

    PubMed

    Xu, Shaomao; Yao, Yonggang; Guo, Yuanyuan; Zeng, Xiaoqiao; Lacey, Steven D; Song, Huiyu; Chen, Chaoji; Li, Yiju; Dai, Jiaqi; Wang, Yanbin; Chen, Yanan; Liu, Boyang; Fu, Kun; Amine, Khalil; Lu, Jun; Hu, Liangbing

    2018-01-01

    The lithium-air (Li-O 2 ) battery has been deemed one of the most promising next-generation energy-storage devices due to its ultrahigh energy density. However, in conventional porous carbon-air cathodes, the oxygen gas and electrolyte often compete for transport pathways, which limit battery performance. Here, a novel textile-based air cathode is developed with a triple-phase structure to improve overall battery performance. The hierarchical structure of the conductive textile network leads to decoupled pathways for oxygen gas and electrolyte: oxygen flows through the woven mesh while the electrolyte diffuses along the textile fibers. Due to noncompetitive transport, the textile-based Li-O 2 cathode exhibits a high discharge capacity of 8.6 mAh cm -2 , a low overpotential of 1.15 V, and stable operation exceeding 50 cycles. The textile-based structure can be applied to a range of applications (fuel cells, water splitting, and redox flow batteries) that involve multiple phase reactions. The reported decoupled transport pathway design also spurs potential toward flexible/wearable Li-O 2 batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. CoMn2O4-supported functionalized carbon nanotube: efficient catalyst for oxygen reduction in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Zhu, Nengwu; Lu, Yu; Liu, Bowen; Zhang, Taiping; Huang, Jianjian; Shi, Chaohong; Wu, Pingxiao; Dang, Zhi; Wang, Ruixin

    2017-10-01

    Recently, the synthesis of nonprecious metal catalysts with low cost and high oxygen reduction reaction (ORR) efficiency is paid much attention in field of microbial fuel cells (MFCs). Transition metal oxides (AMn2O4, A = Co、Ni, and Zn) supported on carbon materials such as graphene and carbon nanotube exhibit stronger electroconductivity and more active sites comparing to bare AMn2O4. Herein, we demonstrate an easy operating Hummer's method to functionalize carbon nanotubes (CNTs) with poly (diallyldimethylammonium chloride) in order to achieve effective loading of CoMn2O4 nanoparticles, named CoMn2O4/PDDA-CNTs (CMODT). After solvothermal treatment, nanoscale CoMn2O4 particles ( 80 nm) were successfully attached on the noncovalent functionalized carbon nanotube. Results show that such composites possess an outstanding electrocatalytic activity towards ORR comparable to the commercial Pt/C catalyst in neutral media. Electrochemical detections as cyclic voltammogram (CV) and rotating ring-disk electrode tests (RRDE) showed that the potential of oxygen reduction peak of 30% CMODT was at - 0.3 V (vs Ag/AgCl), onset potential was at + 0.4 V. Among them, 30% CMODT composite appeared the best candidate of oxygen reduction via 3.9 electron transfer pathway. When 30% CMODT composite was utilized as cathode catalyst in air cathode MFC, the reactor obtained 1020 mW m-2 of the highest maximum power density and 0.781 V of open circuit voltage. The excellent activity and low cost (0.2 g-1) of the hybrid materials demonstrate the potential of transition metal oxide/carbon as effective cathode ORR catalyst for microbial fuel cells. [Figure not available: see fulltext.

  16. Novel microbial fuel cell design to operate with different wastewaters simultaneously.

    PubMed

    Mathuriya, Abhilasha Singh

    2016-04-01

    A novel single cathode chamber and multiple anode chamber microbial fuel cell design (MAC-MFC) was developed by incorporating multiple anode chambers into a single unit and its performance was checked. During 60 days of operation, performance of MAC-MFC was assessed and compared with standard single anode/cathode chamber microbial fuel cell (SC-MFC). The tests showed that MAC-MFC generated stable and higher power outputs compared with SC-MFC and each anode chamber contributed efficiently. Further, MAC-MFCs were incorporated with different wastewaters in different anode chambers and their behavior in MFC performance was observed. MAC-MFC efficiently treated multiple wastewaters simultaneously at low cost and small space, which claims its candidature for future possible scale-up applications. Copyright © 2015. Published by Elsevier B.V.

  17. Performance evaluation of a hybrid system for efficient palm oil mill effluent treatment via an air-cathode, tubular upflow microbial fuel cell coupled with a granular activated carbon adsorption.

    PubMed

    Tee, Pei-Fang; Abdullah, Mohammad Omar; Tan, Ivy Ai Wei; Mohamed Amin, Mohamed Afizal; Nolasco-Hipolito, Cirilo; Bujang, Kopli

    2016-09-01

    An air-cathode MFC-adsorption hybrid system, made from earthen pot was designed and tested for simultaneous wastewater treatment and energy recovery. Such design had demonstrated superior characteristics of low internal resistance (29.3Ω) and favor to low-cost, efficient wastewater treatment and power generation (55mW/m(3)) with average current of 2.13±0.4mA. The performance between MFC-adsorption hybrid system was compared to the standalone adsorption system and results had demonstrated great pollutants removals of the integrated system especially for chemical oxygen demand (COD), biochemical oxygen demand (BOD3), total organic carbon (TOC), total volatile solids (TVS), ammoniacal nitrogen (NH3-N) and total nitrogen (TN) because such system combines the advantages of each individual unit. Besides the typical biological and electrochemical processes that happened in an MFC system, an additional physicochemical process from the activated carbon took place simultaneously in the MFC-adsorption hybrid system which would further improved on the wastewater quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Anolyte recycling enhanced bioelectricity generation of the buffer-free single-chamber air-cathode microbial fuel cell.

    PubMed

    Ren, Yueping; Chen, Jinli; Shi, Yugang; Li, Xiufen; Yang, Na; Wang, Xinhua

    2017-11-01

    Anolyte acidification is an inevitable restriction for the bioelectricity generation of buffer-free microbial fuel cells (MFCs). In this work, acidification of the buffer-free KCl anolyte has been thoroughly eliminated through anolyte recycling. The accumulated HCO 3 - concentration in the recycled KCl anolyte was above 50mM, which played as natural buffer and elevated the anolyte pH to above 8. The maximum power density (P max ) increased from 322.9mWm -2 to 527.2mWm -2 , which is comparable with the phosphate buffered MFC. Besides Geobacter genus, the gradually increased anolyte pH and conductivity induced the growing of electrochemically active Geoalkalibacter genus, in the anode biofilm. Anolyte recycling is a feasible strategy to strengthen the self-buffering capacity of buffer-free MFCs, thoroughly eliminate the anolyte acidification and prominently enhance the electric power. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Sintered wire cathode

    DOEpatents

    Falce, Louis R [San Jose, CA; Ives, R Lawrence [Saratoga, CA

    2009-06-09

    A porous cathode structure is fabricated from a plurality of wires which are placed in proximity to each other in elevated temperature and pressure for a sintering time. The sintering process produces the porous cathode structure which may be divided into a plurality of individual porous cathodes, one of which may be placed into a dispenser cathode support which includes a cavity for containing a work function reduction material such as BaO, CaO, and Al.sub.2O.sub.3. The work function reduction material migrates through the pores of the porous cathode from a work replenishment surface adjacent to the cavity of the dispenser cathode support to an emitting cathode surface, thereby providing a dispenser cathode which has a uniform work function and therefore a uniform electron emission.

  20. Solid phase microbial fuel cell (SMFC) for harnessing bioelectricity from composite food waste fermentation: influence of electrode assembly and buffering capacity.

    PubMed

    Mohan, S Venkata; Chandrasekhar, K

    2011-07-01

    Solid phase microbial fuel cells (SMFC; graphite electrodes; open-air cathode) were designed to evaluate the potential of bioelectricity production by stabilizing composite canteen based food waste. The performance was evaluated with three variable electrode-membrane assemblies. Experimental data depicted feasibility of bioelectricity generation from solid state fermentation of food waste. Distance between the electrodes and presence of proton exchange membrane (PEM) showed significant influence on the power yields. SMFC-B (anode placed 5 cm from cathode-PEM) depicted good power output (463 mV; 170.81 mW/m(2)) followed by SMFC-C (anode placed 5 cm from cathode; without PEM; 398 mV; 53.41 mW/m(2)). SMFC-A (PEM sandwiched between electrodes) recorded lowest performance (258 mV; 41.8 mW/m(2)). Sodium carbonate amendment documented marked improvement in power yields due to improvement in the system buffering capacity. SMFCs operation also documented good substrate degradation (COD, 76%) along with bio-ethanol production. The operation of SMFC mimicked solid-sate fermentation which might lead to sustainable solid waste management practices. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Electricity generation coupled with wastewater treatment using a microbial fuel cell composed of a modified cathode with a ceramic membrane and cellulose acetate film.

    PubMed

    Seo, Ha Na; Lee, Woo Jin; Hwang, Tae Sik; Park, Doo Hyun

    2009-09-01

    A noncompartmented microbial fuel cell (NCMFC) composed of a Mn(IV)-carbon plate and a Fe(III)-carbon plate was used for electricity generation from organic wastewater without consumption of external energy. The Fe(III)-carbon plate, coated with a porous ceramic membrane and a semipermeable cellulose acetate film, was used as a cathode, which substituted for the catholyte and cathode. The Mn(IV)-carbon plate was used as an anode without a membrane or film coating. A solar cell connected to the NCMFC activated electricity generation and bacterial consumption of organic matter contained in the wastewater. More than 99 degrees of the organic matter was biochemically oxidized during wastewater flow through the four NCMFC units. A predominant bacterium isolated from the anode surface in both the conventional and the solar cell-linked NCMFC was found to be more than 99 degrees similar to a Mn(II)-oxidizing bacterium and Burkeholderia sp., based on 16S rDNA sequence analysis. The isolate reacted electrochemically with the Mn(IV)-modified anode and produced electricity in the NCMFC. After 90 days of incubation, a bacterial species that was enriched on the Mn(IV)-modified anode surface in all of the NCMFC units was found to be very similar to the initially isolated predominant species by comparing 16S rDNA sequences.

  2. Ferroelectric Emission Cathodes for Low-Power Electric Propulsion

    NASA Technical Reports Server (NTRS)

    Kovaleski, Scott D.; Burke, Tom (Technical Monitor)

    2002-01-01

    Low- or no-flow electron emitters are required for low-power electric thrusters, spacecraft plasma contactors, and electrodynamic tether systems to reduce or eliminate the need for propellant/expellant. Expellant-less neutralizers can improve the viability of very low-power colloid thrusters, field emission electric propulsion devices, ion engines, Hall thrusters, and gridded vacuum arc thrusters. The NASA Glenn Research Center (GRC) is evaluating ferroelectric emission (FEE) cathodes as zero expellant flow rate cathode sources for the applications listed above. At GRC, low voltage (100s to approx. 1500 V) operation of FEE cathodes is examined. Initial experiments, with unipolar, bipolar, and RF burst applied voltage, have produced current pulses 250 to 1000 ns in duration with peak currents of up to 2 A at voltages at or below 1500 V. In particular, FEE cathodes driven by RF burst voltages from 1400 to 2000 V peak to peak, at burst frequencies from 70 to 400 kHz, emitted average current densities from 0.1 to 0.7 A/sq cm. Pulse repeatability as a function of input voltage has been initially established. Reliable emission has been achieved in air background at pressures as high as 10(exp -6) Torr.

  3. Actual measurement, hygrothermal response experiment and growth prediction analysis of microbial contamination of central air conditioning system in Dalian, China

    PubMed Central

    Lv, Yang; Hu, Guangyao; Wang, Chunyang; Yuan, Wenjie; Wei, Shanshan; Gao, Jiaoqi; Wang, Boyuan; Song, Fangchao

    2017-01-01

    The microbial contamination of central air conditioning system is one of the important factors that affect the indoor air quality. Actual measurement and analysis were carried out on microbial contamination in central air conditioning system at a venue in Dalian, China. Illumina miseq method was used and three fungal samples of two units were analysed by high throughput sequencing. Results showed that the predominant fungus in air conditioning unit A and B were Candida spp. and Cladosporium spp., and two fungus were further used in the hygrothermal response experiment. Based on the data of Cladosporium in hygrothermal response experiment, this paper used the logistic equation and the Gompertz equation to fit the growth predictive model of Cladosporium genera in different temperature and relative humidity conditions, and the square root model was fitted based on the two environmental factors. In addition, the models were carried on the analysis to verify the accuracy and feasibility of the established model equation. PMID:28367963

  4. Actual measurement, hygrothermal response experiment and growth prediction analysis of microbial contamination of central air conditioning system in Dalian, China.

    PubMed

    Lv, Yang; Hu, Guangyao; Wang, Chunyang; Yuan, Wenjie; Wei, Shanshan; Gao, Jiaoqi; Wang, Boyuan; Song, Fangchao

    2017-04-03

    The microbial contamination of central air conditioning system is one of the important factors that affect the indoor air quality. Actual measurement and analysis were carried out on microbial contamination in central air conditioning system at a venue in Dalian, China. Illumina miseq method was used and three fungal samples of two units were analysed by high throughput sequencing. Results showed that the predominant fungus in air conditioning unit A and B were Candida spp. and Cladosporium spp., and two fungus were further used in the hygrothermal response experiment. Based on the data of Cladosporium in hygrothermal response experiment, this paper used the logistic equation and the Gompertz equation to fit the growth predictive model of Cladosporium genera in different temperature and relative humidity conditions, and the square root model was fitted based on the two environmental factors. In addition, the models were carried on the analysis to verify the accuracy and feasibility of the established model equation.

  5. Synergistic Effects between Doped Nitrogen and Phosphorus in Metal-Free Cathode for Zinc-Air Battery from Covalent Organic Frameworks Coated CNT.

    PubMed

    Li, Zhongtao; Zhao, Weinan; Yin, Changzhi; Wei, Liangqin; Wu, Wenting; Hu, Zhenpeng; Wu, Mingbo

    2017-12-27

    A covalent organic framework that is composed of hexachlorocyclotriphosphazene and dicyanamide has been coated on CNT to prepare metal-free oxygen reduction reaction catalyst through thermal polymerization of the Zn-air battery cathode. The N,P-codoped nanohybrids have highly porous structure and active synergistic effect between graphitic-N and -P, which promoted the electrocatalytic performance. The electrocatalysts exhibits remarkable half-wave potential (-0.162 V), high current density (6.1 mA/cm -2 ), good stability (83%), and excellent methanol tolerance for ORR in alkaline solution. Furthermore, the N,P-codoped nanohybrids were used as an air electrode for fabrication of a high performance Zn-air battery. The battery achieves a high open-circuit potential (1.53 V) and peak power density (0.255 W cm -2 ). Moreover, the effect of N,P codoping on the conjugate carbon system and the synergistic effect between graphitic-N and P have been calculated through density functional theory calculations, which are essentially in agreement with experimental data.

  6. Synthesis cathode material LiNi0.80Co0.15Al0.05O2 with two step solid-state method under air stream

    NASA Astrophysics Data System (ADS)

    Xia, Shubiao; Zhang, Yingjie; Dong, Peng; Zhang, Yannan

    2014-01-01

    A facile generic strategy of solid-state reaction under air atmosphere is employed to prepare LiNi0.8Co0.15Al0.05O2 layer structure micro-sphere as cathodes for Li-ion batteries. The impurity phase has been eliminated wholly without changing the R-3m space group of LiNi0.8Co0.15Al0.05O2. The electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathodes depend on the sintering step, temperature, particle size and uniformity. The sample pre-sintered at 540 °C for 12 h and then sintered at 720 °C for 28 h exhibits the best electrochemical performance, which delivers a reversible capacity of 180.4, 165.8, 154.7 and 135.6 mAhg-1 at 0.2 C, 1 C, 2 C and 5 C, respectively. The capacity retention keeps over 87% after 76 cycles at 1 C. This method is simple, cheap and mass-productive, and thus suitable to large scale production of NCA cathodes directly used for lithium ion batteries.

  7. Performance of denitrifying microbial fuel cell subjected to variation in pH, COD concentration and external resistance.

    PubMed

    Li, Jin-Tao; Zhang, Shao-Hui; Hua, Yu-Mei

    2013-01-01

    The effects of pH, chemical oxygen demand (COD) concentration and external resistance on denitrifying microbial fuel cell were evaluated in terms of electricity generation characteristics and pollutant removal performance. The results showed that anodic influent with weakly alkaline or neutral pH and cathodic influent with weakly acidic pH favored pollutant removal and electricity generation. The suitable influent pH of the anode and cathode were found to be 7.5-8.0 and 6.0-6.5, respectively. In the presence of sufficient nitrate in the cathode, higher influent COD concentration led to more electricity generation and greater pollutant removal rates. With an anodic influent pH of 8.0 and a cathodic influent pH of 6.0, an influent COD concentration of 400 mg/L was deemed to be appropriate. Low external resistance favored nitrate and COD removal. The results suggest that operation of denitrifying microbial fuel cell at a lower external resistance would be desirable for pollutant removal but not electricity generation.

  8. Evaluation of organic matter removal and electricity generation by using integrated microbial fuel cells for wastewater treatment.

    PubMed

    Yamashita, Takahiro; Ishida, Mitsuyoshi; Ogino, Akifumi; Yokoyama, Hiroshi

    2016-01-01

    A floating all-in-one type of microbial fuel cell (Fa-MFC) that allows simple operation and installation in existing wastewater reservoirs for decomposition of organic matter was designed. A prototype cell was constructed by fixing a tubular floater to an assembly composed of a proton-exchange membrane and an air-cathode. To compare anode materials, carbon-cloth anodes or carbon-brush anodes were included in the assembly. The fabricated assemblies were floated in 1-L beakers filled with acetate medium. Both reactors removed acetate at a rate of 133-181 mg/L/d. The Fa-MFC quipped with brush anodes generated a 1.7-fold higher maximum power density (197 mW/m(2)-cathode area) than did that with cloth anodes (119 mW/m(2)-cathode area). To evaluate the performance of the Fa-MFCs on more realistic substrates, artificial wastewater, containing peptone and meat extract, was placed in a 2-L beaker, and the Fa-MFC with brush anodes was floated in the beaker. The Fa-MFC removed the chemical oxygen demand of the wastewater at a rate of 465-1029 mg/L/d, and generated a maximum power density of 152 mW/m(2)-cathode area. When the Fa-MFC was fed with actual livestock wastewater, the biological oxygen demand of the wastewater was removed at a rate of 45-119 mg/L/d, with electricity generation of 95 mW/m(2)-cathode area. Bacteria related to Geobacter sulfurreducens were predominantly detected in the anode biofilm, as deduced from the analysis of the 16S rRNA gene sequence.

  9. Electrosynthesis of Commodity Chemicals by an Autotrophic Microbial Community

    PubMed Central

    Marshall, Christopher W.; Ross, Daniel E.; Fichot, Erin B.; Norman, R. Sean

    2012-01-01

    A microbial community originating from brewery waste produced methane, acetate, and hydrogen when selected on a granular graphite cathode poised at −590 mV versus the standard hydrogen electrode (SHE) with CO2 as the only carbon source. This is the first report on the simultaneous electrosynthesis of these commodity chemicals and the first description of electroacetogenesis by a microbial community. Deep sequencing of the active community 16S rRNA revealed a dynamic microbial community composed of an invariant Archaea population of Methanobacterium spp. and a shifting Bacteria population. Acetobacterium spp. were the most abundant Bacteria on the cathode when acetogenesis dominated. Methane was generally the dominant product with rates increasing from <1 to 7 mM day−1 (per cathode liquid volume) and was concomitantly produced with acetate and hydrogen. Acetogenesis increased to >4 mM day−1 (accumulated to 28.5 mM over 12 days), and methanogenesis ceased following the addition of 2-bromoethanesulfonic acid. Traces of hydrogen accumulated during initial selection and subsequently accelerated to >11 mM day−1 (versus 0.045 mM day−1 abiotic production). The hypothesis of electrosynthetic biocatalysis occurring at the microbe-electrode interface was supported by a catalytic wave (midpoint potential of −460 mV versus SHE) in cyclic voltammetry scans of the biocathode, the lack of redox active components in the medium, and the generation of comparatively high amounts of products (even after medium exchange). In addition, the volumetric production rates of these three commodity chemicals are marked improvements for electrosynthesis, advancing the process toward economic feasibility. PMID:23001672

  10. Air sampling procedures to evaluate microbial contamination: a comparison between active and passive methods in operating theatres.

    PubMed

    Napoli, Christian; Marcotrigiano, Vincenzo; Montagna, Maria Teresa

    2012-08-02

    Since air can play a central role as a reservoir for microorganisms, in controlled environments such as operating theatres regular microbial monitoring is useful to measure air quality and identify critical situations. The aim of this study is to assess microbial contamination levels in operating theatres using both an active and a passive sampling method and then to assess if there is a correlation between the results of the two different sampling methods. The study was performed in 32 turbulent air flow operating theatres of a University Hospital in Southern Italy. Active sampling was carried out using the Surface Air System and passive sampling with settle plates, in accordance with ISO 14698. The Total Viable Count (TVC) was evaluated at rest (in the morning before the beginning of surgical activity) and in operational (during surgery). The mean TVC at rest was 12.4 CFU/m3 and 722.5 CFU/m2/h for active and passive samplings respectively. The mean in operational TVC was 93.8 CFU/m3 (SD = 52.69; range = 22-256) and 10496.5 CFU/m2/h (SD = 7460.5; range = 1415.5-25479.7) for active and passive samplings respectively. Statistical analysis confirmed that the two methods correlate in a comparable way with the quality of air. It is possible to conclude that both methods can be used for general monitoring of air contamination, such as routine surveillance programs. However, the choice must be made between one or the other to obtain specific information.

  11. Ecological succession of the microbial communities of an air-conditioning cooling coil in the tropics.

    PubMed

    Acerbi, E; Chénard, C; Miller, D; Gaultier, N E; Heinle, C E; Chang, V W-C; Uchida, A; Drautz-Moses, D I; Schuster, S C; Lauro, F M

    2017-03-01

    Air-conditioning systems harbor microorganisms, potentially spreading them to indoor environments. While air and surfaces in air-conditioning systems are periodically sampled as potential sources of indoor microbes, little is known about the dynamics of cooling coil-associated communities and their effect on the downstream airflow. Here, we conducted a 4-week time series sampling to characterize the succession of an air-conditioning duct and cooling coil after cleaning. Using an universal primer pair targeting hypervariable regions of the 16S/18S ribosomal RNA, we observed a community succession for the condensed water, with the most abundant airborne taxon Agaricomycetes fungi dominating the initial phase and Sphingomonas bacteria becoming the most prevalent taxa toward the end of the experiment. Duplicate air samples collected upstream and downstream of the coil suggest that the system does not act as ecological filter or source/sink for specific microbial taxa during the duration of the experiment. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. Lithium-air batteries, method for making lithium-air batteries

    DOEpatents

    Vajda, Stefan; Curtiss, Larry A.; Lu, Jun; Amine, Khalil; Tyo, Eric C.

    2016-11-15

    The invention provides a method for generating Li.sub.2O.sub.2 or composites of it, the method uses mixing lithium ions with oxygen ions in the presence of a catalyst. The catalyst comprises a plurality of metal clusters, their alloys and mixtures, each cluster consisting of between 3 and 18 metal atoms. The invention also describes a lithium-air battery which uses a lithium metal anode, and a cathode opposing the anode. The cathode supports metal clusters, each cluster consisting of size selected clusters, taken from a range of between approximately 3 and approximately 18 metal atoms, and an electrolyte positioned between the anode and the cathode.

  13. Electricity generation from carbon monoxide in a single chamber microbial fuel cell.

    PubMed

    Mehta, P; Hussain, A; Tartakovsky, B; Neburchilov, V; Raghavan, V; Wang, H; Guiot, S R

    2010-05-05

    Electricity production from carbon monoxide (CO) is demonstrated in a single chamber microbial fuel cell (MFC) with a CoTMPP-based air cathode. The MFC was inoculated with anaerobic sludge and continuously sparged with CO as a sole carbon source. Volumetric power output was maximized at a CO flow rate of 4.8LLR(-1)d(-1) reaching 6.4mWLR(-1). Several soluble and gaseous degradation products including hydrogen, methane, and acetate were detected, resulting in a relatively low apparent Coulombic efficiency of 8.7%. Tests also demonstrated electricity production from hydrogen and acetate with the highest and fastest increase in voltage exhibited after acetate injection. It is hypothesized that electricity generation in a CO-fed MFC is accomplished by a consortium of carboxydotrophic and carbon monoxide - tolerant anodophilic microorganisms. Crown Copyright © 2010. Published by Elsevier Inc. All rights reserved.

  14. Electrochemical surface modification of carbon mesh anode to improve the performance of air-cathode microbial fuel cells.

    PubMed

    Luo, Jianmei; Chi, Meiling; Wang, Hongyu; He, Huanhuan; Zhou, Minghua

    2013-12-01

    A convenient and promising alternative to surface modification of carbon mesh anode was fulfilled by electrochemical oxidation in the electrolyte of nitric acid or ammonium nitrate at ambient temperature. It was confirmed that such an anode modification method was low cost and effective not only in improving the efficiency of power generation in microbial fuel cells (MFCs) for synthetic wastewater treatment, but also helping to reduce the period for MFCs start-up. The MFCs with anode modification in electrolyte of nitric acid performed the best, achieving a Coulombic efficiency enhancement of 71 %. As characterized, the electrochemical modification resulted in the decrease of the anode potential and internal resistance but the increase of current response and nitrogen-containing and oxygen-containing functional groups on the carbon surface, which might contribute to the enhancement on the performances of MFCs.

  15. New design of a cathode flow-field with a sub-channel to improve the polymer electrolyte membrane fuel cell performance

    NASA Astrophysics Data System (ADS)

    Wang, Yulin; Yue, Like; Wang, Shixue

    2017-03-01

    The cathode flow-field design of polymer electrolyte membrane (PEM) fuel cells determines the distribution of reactant gases and the removal of liquid water. A suitable design can result in perfect water management and thus high cell performance. In this paper, a new design for a cathode flow-field with a sub-channel was proposed and had been experimentally analyzed in a parallel flow-field PEM fuel cell. Three sub-channel inlets were placed along the cathode channel. The main-channel inlet was fed with moist air to humidify the membrane and maintain high proton conductivity, whereas, the sub-channel inlet was fed with dry air to enhance water removal in the flow channel. The experimental results indicated that the sub-channel design can decrease the pressure drop in the flow channel, and the sub-channels inlet positions (SIP, where the sub-channel inlets were placed along the cathode channel) and flow rates (SFR, percentage of air from the sub-channel inlet in the total cathode flow rate) had a considerable impact on water removal and cell performance. A proposed design that combines the SIP and SFR can effectively eliminate water from the fuel cell, increasing the maximum power density by more than 13.2% compared to the conventional design.

  16. Concurrent Phosphorus Recovery and Energy Generation in Mediator-Less Dual Chamber Microbial Fuel Cells: Mechanisms and Influencing Factors.

    PubMed

    Almatouq, Abdullah; Babatunde, Akintunde O

    2016-03-29

    This study investigated the mechanism and key factors influencing concurrent phosphorus (P) recovery and energy generation in microbial fuel cells (MFC) during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite when ammonium and magnesium chloride solutions were added to the cathode chamber. Monitoring data for chemical oxygen demand (COD), pH, oxidation reduction potential (ORP) and aeration flow rate showed that a maximum 38% P recovery was achieved; and this corresponds to 1.5 g/L, pH > 8, -550 ± 10 mV and 50 mL/min respectively, for COD, pH(cathode), ORP and cathode aeration flow rate. More importantly, COD and aeration flow rate were shown to be the key influencing factors for the P recovery and energy generation. Results further show that the maximum P recovery corresponds to 72 mW/m² power density. However, the energy generated at maximum P recovery was not the optimum; this shows that whilst P recovery and energy generation can be concurrently achieved in a microbial fuel cell, neither can be at the optimal value.

  17. Microbial fuel cells: Their application and microbiology

    NASA Astrophysics Data System (ADS)

    He, Zhen

    The energy crisis is an urgent global issue due to the increased consumption of the finite amount of fossil fuel. As a result, looking for alternative energy sources is of critical importance. Microbial fuel cell (MFC) technology can extract electric energy from wastewater, and thus is a sustainable approach to supply energy to our electricity-based society. My research focuses on the development of a suitable MFC reactor for wastewater treatment and the understanding of the microbial function in the MFC process. First, together with colleagues, I have developed a novel MFC reactor, named upflow microbial fuel cell (UMFC), by combining upflow and MFC technologies. The power output from the UMFC was improved by 10-fold after it was modified with a U-shape cathode. The UMFC appears to be a practical reactor for continuous operation, though the output of electric power requires further improvement. In addition, a sediment MFC with a rotating cathode was also developed and its performance was examined. Second, I have adopted a human distal gut anaerobe, Bacteroides thetaiotaomicron, as the model organism to study the role of fermentative bacterium in electricity generation. When B. thetaiotaomicron grew under an applied electric potential, an electric current was generated. GeneChip data indicated that this bacterium did not alter its metabolism during this process. Although B. thetaiotaomicron may not be capable of respiration with an electrode as the electron acceptor, the experiment has demonstrated that fermentative bacteria may play an important role in electricity generation.

  18. Phosphate recovery as struvite within a single chamber microbial electrolysis cell.

    PubMed

    Cusick, Roland D; Logan, Bruce E

    2012-03-01

    An energy efficient method of concurrent hydrogen gas and struvite (MgNH(4)PO(4)·6H(2)O) production was investigated based on bioelectrochemically driven struvite crystallization at the cathode of a single chamber microbial electrolysis struvite-precipitation cell (MESC). The MESC cathodes were either stainless steel 304 mesh or flat plates. Phosphate removal ranged from 20% to 40%, with higher removals obtained using mesh cathodes than with flat plates. Cathode accumulated crystals were verified as struvite using a scanning electron microscope capable of energy dispersive spectroscopy (SEM-EDS). Crystal accumulation did not affect the rate of hydrogen production in struvite reactors. The rate of struvite crystallization (g/m(2)-h) and hydrogen production (m(3)/m(3)-d) were shown to be dependent on applied voltage and cathode material. Overall energy efficiencies (substrate and electricity) were high (73 ± 4%) and not dependent on applied voltage. These results show that MESCs may be useful both as a method for hydrogen gas and struvite production. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Sustainable water desalination and electricity generation in a separator coupled stacked microbial desalination cell with buffer free electrolyte circulation.

    PubMed

    Chen, Xi; Liang, Peng; Wei, Zhimou; Zhang, Xiaoyuan; Huang, Xia

    2012-09-01

    A separator coupled circulation stacked microbial desalination cell (c-SMDC-S) was constructed to stabilize the pH imbalances in MDCs without buffer solution and achieved the stable desalination. The long-term operation of c-SMDC-S, regular stacked MDC (SMDC) and no separator coupled circulation SMDC (c-SMDC) were tested. The SMDC and c-SMDC could only stably operate for 1 week and 1 month owing to dramatic anolyte pH decrease and serious biofilm growth on the air cathode, respectively. The c-SMDC-S gained in anolyte alkalinity and operated stably for about 60 days without the thick biofilm growth on cathode. Besides, the chemical oxygen demand removal and coulombic efficiency were 64 ± 6% and 30 ± 2%, higher than that of SMDC and c-SMDC, respectively. It was concluded that the circulation of alkalinity could remove pH imbalance while the separator could expand the operation period and promote the conversion of organic matter to electricity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Light-dependent processes on the cathode enhance the electrical outputs of sediment microbial fuel cells.

    PubMed

    Bardarov, Ivo; Mitov, Mario; Ivanova, Desislava; Hubenova, Yolina

    2018-02-27

    In this study, we explored in details the influence of the light irradiation on the SMFCs electrical outputs. The experiments at both natural and artificial illumination firmly show that during the photoperiods the current grows up. The intensity of the current increase depends on the duration of the photoperiod as well as on the wavelength of the monochromatic light source applied. The highest influence of the light irradiation has been obtained at wavelengths, corresponding to the absorption peaks of essential pigments in the light-harvesting system of oxygenic photosynthesizing microorganisms. The decreased values as well as the discontinued fluctuations of the current as a result of suppressed illumination or substitution of the biocathode with a new one suggest that photosynthesizing microorganisms, co-existing in the cathodic biofilm consortium, contribute to the overall SMFC performance. The microscopic observations confirm the existence of chlorophyll-containing microorganisms on the cathode surface. Though the performed metagenomics DNA analysis has not certified a dominance of photosynthesizing microorganisms, all other results support the hypothesis that the current enhance during the photoperiods is due to the in situ bio-oxygen production on the cathode surface, thus lowering the mass transport limitations for the oxygen reduction reaction. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Planar-focusing cathodes.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lewellen, J. W.; Noonan, J.; Accelerator Systems Division

    2005-01-01

    Conventional {pi}-mode rf photoinjectors typically use magnetic solenoids for emittance compensation. This provides independent focusing strength but can complicate rf power feed placement, introduce asymmetries (due to coil crossovers), and greatly increase the cost of the photoinjector. Cathode-region focusing can also provide for a form of emittance compensation. Typically this method strongly couples focusing strength to the field gradient on the cathode, however, and usually requires altering the longitudinal position of the cathode to change the focusing. We propose a new method for achieving cathode-region variable-strength focusing for emittance compensation. The new method reduces the coupling to the gradient onmore » the cathode and does not require a change in the longitudinal position of the cathode. Expected performance for an S-band system is similar to conventional solenoid-based designs. This paper presents the results of rf cavity and beam dynamics simulations of the new design. We have proposed a method for performing emittance compensation using a cathode-region focusing scheme. This technique allows the focusing strength to be adjusted somewhat independently of the on-axis field strength. Beam dynamics calculations indicate performance should be comparable to presently in-use emittance compensation schemes, with a simpler configuration and fewer possibilities for emittance degradation due to the focusing optics. There are several potential difficulties with this approach, including cathode material selection, cathode heating, and peak fields in the gun. We hope to begin experimenting with a cathode of this type in the near future, and several possibilities exist for reducing the peak gradients to more acceptable levels.« less

  2. Understanding the impact of operational conditions on performance of microbial peroxide producing cells

    NASA Astrophysics Data System (ADS)

    Young, Michelle N.; Chowdhury, Nadrat; Garver, Emily; Evans, Patrick J.; Popat, Sudeep C.; Rittmann, Bruce E.; Torres, César I.

    2017-07-01

    Microbial peroxide producing cells (MPPCs) are microbial electrochemical cells used to synthesize hydrogen peroxide (H2O2) in the cathode chamber. Catholyte hydraulic retention time (HRT), different catholytes and their concentrations, and a ferrochelating stabilizer are varied in a continuous-flow cathode MPPC to evaluate their impacts on performance. Using NaCl catholytes, the MPPC produced as high as 3.1 ± 0.37 g H2O2 L-1 at a 4-h HRT with as little as 1.13 W-h g-1 H2O2 energy input and with up to 57 g Lcathode-1 d-1 at a 1-h HRT. For these conditions, the H2O2 production rate provides more than 3 times the H2O2 required for disinfection or micro-pollutant removal while using 5-25% of the power used in conventional H2O2 production processes. Attempts to improve H2O2-production by adding weak acid buffers or H2O2-stabilizing EDTA fail for different reasons. The addition of the ferrochelator EDTA to prevent H2O2 auto-decay deteriorates MPPC performance, because EDTA diffuses from the cathode to the anode, inhibiting iron utilization by anode-respiring bacteria. Weak acid buffers failed to reduce cathode concentration overpotentials. Buffering catholytes lowered the H2O2 yield due to large pH gradients at the cathode chamber entrance, causing the formation of H2O instead of H2O2 or O2 re-formation from H2O2 auto-decay.

  3. Air sampling procedures to evaluate microbial contamination: a comparison between active and passive methods in operating theatres

    PubMed Central

    2012-01-01

    Background Since air can play a central role as a reservoir for microorganisms, in controlled environments such as operating theatres regular microbial monitoring is useful to measure air quality and identify critical situations. The aim of this study is to assess microbial contamination levels in operating theatres using both an active and a passive sampling method and then to assess if there is a correlation between the results of the two different sampling methods. Methods The study was performed in 32 turbulent air flow operating theatres of a University Hospital in Southern Italy. Active sampling was carried out using the Surface Air System and passive sampling with settle plates, in accordance with ISO 14698. The Total Viable Count (TVC) was evaluated at rest (in the morning before the beginning of surgical activity) and in operational (during surgery). Results The mean TVC at rest was 12.4 CFU/m3 and 722.5 CFU/m2/h for active and passive samplings respectively. The mean in operational TVC was 93.8 CFU/m3 (SD = 52.69; range = 22-256) and 10496.5 CFU/m2/h (SD = 7460.5; range = 1415.5-25479.7) for active and passive samplings respectively. Statistical analysis confirmed that the two methods correlate in a comparable way with the quality of air. Conclusion It is possible to conclude that both methods can be used for general monitoring of air contamination, such as routine surveillance programs. However, the choice must be made between one or the other to obtain specific information. PMID:22853006

  4. Evaluation of Cation Migration in Lanthanum Strontium Cobalt Ferrite Solid Oxide Fuel Cell Cathodes via In-operando X-ray Diffraction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hardy, John S.; Coyle, Christopher A.; Bonnett, Jeff F.

    2018-01-28

    Anode-supported SOFCs with LSCF-6428 cathodes were operated at various temperatures for hundreds of hours in dry or humid (~3% water) cathode air with continuous cathode XRD. Additionally, one cell in dry air was held at OCV and another had 12% CO2 added to the humid air. Long cumulative XRD count times allowed identification of minor phases at <0.1 wt%. In humid air, performance improved during the first couple of hundred hours and Fe-rich Fe,Co spinel XRD peaks gradually shifted to lower angles while nano-nodules formed on LSCF surfaces. With 12% CO2 added, performance degraded after initial activation, unlike without CO2,more » where stability followed activation. In CO2, LSCF XRD peaks shifted indicating gradual decomposition. In dry air, fast initial degradation that decelerated over time occurred at constant current while the cell at OCV was stable. At OCV and 750°C or at constant current and 700°C in dry air, Fe-rich spinel XRD peaks shifted more slowly than in humid air tests; Co-rich Fe,Co spinel peaks shifted to higher angles; and SEM discovered smaller nano-nodules on LSCF than after humid air tests. At constant current at 750°C and 800°C in dry air, no nano-nodules or gradual changes in the XRD patterns were discovered.« less

  5. Bi-metallic nanoparticles as cathode electrocatalysts

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lu, Jun; Amine, Khalil; Wang, Xiaoping

    A lithium-air battery cathode catalyst includes core-shell nanoparticles on a carbon support, wherein: a core of the core-shell nanoparticles is platinum metal; and a shell of the core-shell nanoparticles is copper metal; wherein: the core-shell nanoparticles have a weight ratio of the copper metal to the platinum metal from about 4% to about 6% copper to from about 2% to about 12% platinum, with a remaining percentage being the carbon support.

  6. Energy-positive wastewater treatment and desalination in an integrated microbial desalination cell (MDC)-microbial electrolysis cell (MEC)

    NASA Astrophysics Data System (ADS)

    Li, Yan; Styczynski, Jordyn; Huang, Yuankai; Xu, Zhiheng; McCutcheon, Jeffrey; Li, Baikun

    2017-07-01

    Simultaneous removal of nitrogen in municipal wastewater, metal in industrial wastewater and saline in seawater was achieved in an integrated microbial desalination cell-microbial electrolysis cell (MDC-MEC) system. Batch tests showed that more than 95.1% of nitrogen was oxidized by nitrification in the cathode of MDC and reduced by heterotrophic denitrification in the anode of MDC within 48 h, leading to the total nitrogen removal rate of 4.07 mg L-1 h-1. Combining of nitrogen removal and desalination in MDC effectively solved the problem of pH fluctuation in anode and cathode, and led to 63.7% of desalination. Power generation of MDC (293.7 mW m-2) was 2.9 times higher than the one without salt solution. The electric power of MDC was harvested by a capacitor circuit to supply metal reduction in a MEC, and 99.5% of lead (II) was removed within 48 h. A kinetic MDC model was developed to elucidate the correlation of voltage output and desalination efficiency. Ratio of wastewater and sea water was calculated for MDC optimal operation. Energy balance of nutrient removal, metal removal and desalination in the MDC-MEC system was positive (0.0267 kW h m-3), demonstrating the promise of utilizing low power output of MDCs.

  7. Microbial communities in air and wine of a winery at two consecutive vintages.

    PubMed

    Pérez-Martín, Fátima; Seseña, Susana; Fernández-González, Mónica; Arévalo, María; Palop, María Llanos

    2014-11-03

    The aim of this study was to assess, both quantitatively and qualitatively, the populations of lactic acid bacteria (LAB) and yeasts in air and wine of a winery, in order to evaluate the possible exchange of microorganisms between them. Samples were taken in a winery located in Castilla-La Mancha (Spain) during the winemaking period of two consecutive vintages (2011 and 2012). The microbial composition was determined by using both a culture-dependent method and a culture-independent method, PCR-denaturing gradient gel electrophoresis (PCR-DGGE). In addition, genetic characterization of isolates from plates was carried out. A high diversity of species was detected in air and wine samples from both vintages. Leuconostoc mesenteroides was the predominant lactic acid bacteria in air from both vintages while Oenococcus oeni was the predominant in wine. Saccharomyces cerevisiae was the most frequently isolated yeast in both air and wine. Typing of O. oeni and S. cerevisiae isolates from air and wine samples showed the presence of coincident genotypes in both samples, that would confirm the exchange of microorganisms between the two environments, air and wine, and furthermore some of these genotypes were also found at samples taken at different vintages, indicating that they would remain in the winery. The results display the influence of the activity taking place in the winery and the moment of fermentation of the wines in tanks, on the microorganisms present in the air and the role of the air for the dispersal of microorganisms within the winery. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Microbial fuel cell characterisation and evaluation of Lysinibacillus macroides MFC02 electrigenic capability.

    PubMed

    Uma Vanitha, Murugan; Natarajan, Muthusamy; Sridhar, Harikrishnamoorthy; Umamaheswari, Sankaran

    2017-05-01

    Microbial fuel cell (MFC) is the most prominent research field due to its capability to generate electricity by utilizing the renewable sources. In the present study, Two MFC designs namely, H type-Microbial fuel cell (HT-MFC) and U type-Microbial fuel cell (UT-MFC) were constructed based on standardized H shaped anode and cathode compartment as well as U shaped anode and cathode compartments, respectively. In order to lower the cost for MFC construction, Pencil graphite lead was used as electrode and salt agar as Proton exchange membrane. Results inferred that newly constructed UT-MFC showed high electron production when compared to the HT-MFC. UT-MFC displayed an output of about 377 ± 18.85 mV (millivolts); whereas HT-MFC rendered only 237 ± 11.85 mV (millivolts) of power generation, which might be due to the low internal resistance. By increasing the number of cathode in UT-MFC, power production was increased upto 313 ± 15.65 mV in Open circuit voltage (OCV). Electrogenic bacteria namely, Lysinibacillus macroides (Acc. No. KX011879) rendered enriched power generation. The attachment of bacteria as a biofilm on pencil graphite lead was analyzed using fluorescent microscope and Scanning Electron Microscope (SEM). Based on our findings, it was observed that UT-MFC has a tendency to produce high electron generation using pencil graphite lead as the electrode material.

  9. Modified Gold Electrode and Hollow Mn3O4 Nanoparticles as Electrode Materials for Microbial Fuel Cell Applications

    NASA Astrophysics Data System (ADS)

    Dhungana, Pramod

    Microbial fuel cell (MFC) technology has attracted great attention in the scientific community as it offers the possibility of extraction of electricity from wide range of soluble and dissolved organic waste or renewable biomass, including sludge, waste water and cellulosic biomass. Microbial fuel cells are devices that utilize microbial metabolic processes to convert chemical energy via the oxidation of organic substances to produce electric current. MFCs consist of two chambers, an anode and cathode, separated by ion-permeable materials. The efficiency of producing electricity using the MFC depends on several factors such as immobilization of microorganisms on anode, mode of electron transfer, types of substrate/fuel and effectiveness of cathode materials for oxygen reduction reaction (ORR). In this work, in order to immobilize the microorganisms on anode materials, we have investigated the surface modification of gold electrode (anode) using alkyl dithiol and aryl thiol with glucose. The modification processes were characterized by using contact angle measurements and proton nuclear magnetic resonance (NMR). In order to study the effectiveness of cathode materials for ORR, we have synthesized hollow Mn3O 4 nanoparticles which are electrically very poor. Therefore, the hollow nanoparticles were mixed with electrically conductive multi-walled carbon nanotube as support and optimized the mixing process. This composite material shows enhanced ORR activity in all types of pH conditions. In future, we will focus to integrate anode and cathode in MFC to check its efficiency to produce electricity.

  10. Development and Long-Term Stability of a Novel Microbial Fuel Cell BOD Sensor with MnO2 Catalyst

    PubMed Central

    Kharkwal, Shailesh; Tan, Yi Chao; Lu, Min; Ng, How Yong

    2017-01-01

    A novel microbial fuel cell (MFC)-based biosensor was designed for continuous monitoring of biochemical oxygen demand (BOD) in real wastewater. To lower the material cost, manganese dioxide (MnO2) was tested as an innovative cathode catalyst for oxygen reduction in a single chamber air-cathode MFC, and two different crystalline structures obtained during synthesis of MnO2 (namely β- and γ-MnO2) were compared. The BOD sensor was studied in a comprehensive way, using both sodium acetate solution and real domestic wastewater (DWW). The optimal performance of the sensor was obtained with a β-MnO2 catalyst, with R2 values of 0.99 and 0.98 using sodium acetate solution and DWW, respectively. The BOD values predicted by the β-MnO2 biosensor for DWW were in agreement with the BOD5 values, determined according to standard methods, with slight variations in the range from 3% to 12%. Finally, the long-term stability of the BOD biosensor was evaluated over 1.5 years. To the best of our knowledge, this is the first report of an MFC BOD sensor using an MnO2 catalyst at the cathode; the feasibility of using a low-cost catalyst in an MFC for online measurement of BOD in real wastewater broadens the scope of applications for such devices. PMID:28134838

  11. Use of a Burkholderia cenocepacia ABTS Oxidizer in a Microbial Fuel Cell

    USDA-ARS?s Scientific Manuscript database

    Microbial fuel cells (MFCs) often use biological processes to generate electrons from organic material contained in the anode chamber and abiotic processes employing atmospheric oxygen as the oxidant in the cathode chamber. This study investigated the accumulation of an oxidant in bacterial cultures...

  12. Construction and operation of microbial fuel cell with Chlorella vulgaris biocathode for electricity generation.

    PubMed

    Wu, Xia-yuan; Song, Tian-shun; Zhu, Xu-jun; Wei, Ping; Zhou, Charles C

    2013-12-01

    In this study, a modified microbial fuel cell (MFC) with a tubular photobioreactor (PHB) configuration as a cathode compartment was constructed by introducing Chlorella vulgaris to the cathode chamber used to generate oxygen in situ. Two types of cathode materials and light/dark cycles were used to test the effect on MFC with algae biocathode. Results showed that the use of algae is an effective approach because these organisms can act as efficient in situ oxygenators, thereby facilitating the cathodic reaction. Dissolved oxygen and voltage output displayed a clear light positive response and were drastically enhanced compared with the abiotic cathode. In particular, carbon paper-coated Pt used as a cathode electrode increased voltage output at a higher extent than carbon felt used as an electrode. The maximum power density of 24.4 mW/m2 was obtained from the MFC with algae biocathode which utilized the carbon paper-coated Pt as the cathode electrode under intermittent illumination. This density was 2.8 times higher than that of the abiotic cathode. Continuous illumination shortened the algal lifetime. These results demonstrated that intermittent illumination and cathode material-coated catalyst are beneficial to a more efficient and prolonged operation of MFC with C. vulgaris biocathode.

  13. Construction and operation of microbial fuel cell with Chlorella vulgaris biocathode for electricity generation.

    PubMed

    Wu, Xia-yuan; Song, Tian-shun; Zhu, Xu-jun; Wei, Ping; Zhou, Charles C

    2013-12-01

    In this study, a modified microbial fuel cell (MFC) with a tubular photobioreactor (PHB) configuration as a cathode compartment was constructed by introducing Chlorella vulgaris to the cathode chamber used to generate oxygen in situ. Two types of cathode materials and light/dark cycles were used to test the effect on MFC with algae biocathode. Results showed that the use of algae is an effective approach because these organisms can act as efficient in situ oxygenators, thereby facilitating the cathodic reaction. Dissolved oxygen and voltage output displayed a clear light positive response and were drastically enhanced compared with the abiotic cathode. In particular, carbon paper-coated Pt used as a cathode electrode increased voltage output at a higher extent than carbon felt used as an electrode. The maximum power density of 24.4 mW/m(2) was obtained from the MFC with algae biocathode which utilized the carbon paper-coated Pt as the cathode electrode under intermittent illumination. This density was 2.8 times higher than that of the abiotic cathode. Continuous illumination shortened the algal lifetime. These results demonstrated that intermittent illumination and cathode material-coated catalyst are beneficial to a more efficient and prolonged operation of MFC with C. vulgaris biocathode.

  14. The enhancement of ammonium removal from ethanolamine wastewater using air-cathode microbial fuel cells coupled to ferric reduction.

    PubMed

    Shin, Ja-Won; Seo, Seok-Ju; Maitlo, Hubdar Ali; Park, Joo-Yang

    2015-08-01

    A microbial fuel cell (MFC) with biological Fe(III) reduction was implemented for simultaneous ethanolamine (ETA) degradation and electrical energy generation. In the feasibility experiment using acetate as a substrate in a single-chamber MFC with goethite and ammonium at a ratio of 3.0(mol/mol), up to 96.1% of the ammonium was removed through the novel process related to Fe(III). In addition, the highest voltage output (0.53V) and maximum power density (0.49Wm(-2)) were obtained. However, the ammonium removal and electrical performance decreased as acetate was replaced with ETA. In the long-term experiment, the electrical performance markedly decreased where the voltage loss increased due to Fe deposition on the membranes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Metal-air flow batteries using oxygen enriched electrolyte

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zheng, Jian-ping; Andrei, Petru; Shellikeri, Annadanesh

    A metal air flow battery includes an electrochemical reaction unit and an oxygen exchange unit. The electrochemical reaction unit includes an anode electrode, a cathode electrode, and an ionic conductive membrane between the anode and the cathode, an anode electrolyte, and a cathode electrolyte. The oxygen exchange unit contacts the cathode electrolyte with oxygen separate from the electrochemical reaction unit. At least one pump is provided for pumping cathode electrolyte between the electrochemical reaction unit and the oxygen exchange unit. A method for producing an electrical current is also disclosed.

  16. Metal-air flow batteries using oxygen enriched electrolyte

    DOEpatents

    Zheng, Jian-ping; Andrei, Petru; Shellikeri, Annadanesh; Chen, Xujie

    2017-08-01

    A metal air flow battery includes an electrochemical reaction unit and an oxygen exchange unit. The electrochemical reaction unit includes an anode electrode, a cathode electrode, and an ionic conductive membrane between the anode and the cathode, an anode electrolyte, and a cathode electrolyte. The oxygen exchange unit contacts the cathode electrolyte with oxygen separate from the electrochemical reaction unit. At least one pump is provided for pumping cathode electrolyte between the electrochemical reaction unit and the oxygen exchange unit. A method for producing an electrical current is also disclosed.

  17. Outgassing rate analysis of a velvet cathode and a carbon fiber cathode

    NASA Astrophysics Data System (ADS)

    Li, An-Kun; Fan, Yu-Wei; Qian, Bao-Liang; Zhang, Zi-cheng; Xun, Tao

    2017-11-01

    In this paper, the outgassing-rates of a carbon fiber array cathode and a polymer velvet cathode are tested and discussed. Two different methods of measurements are used in the experiments. In one scheme, a method based on dynamic equilibrium of pressure is used. Namely, the cathode works in the repetitive mode in a vacuum diode, a dynamic equilibrium pressure would be reached when the outgassing capacity in the chamber equals the pumping capacity of the pump, and the outgassing rate could be figured out according to this equilibrium pressure. In another scheme, a method based on static equilibrium of pressure is used. Namely, the cathode works in a closed vacuum chamber (a hard tube), and the outgassing rate could be calculated from the pressure difference between the pressure in the chamber before and after the work of the cathode. The outgassing rate is analyzed from the real time pressure evolution data which are measured using a magnetron gauge in both schemes. The outgassing rates of the carbon fiber array cathode and the velvet cathode are 7.3 ± 0.4 neutrals/electron and 85 ± 5 neutrals/electron in the first scheme and 9 ± 0.5 neutrals/electron and 98 ± 7 neutrals/electron in the second scheme. Both the results of two schemes show that the outgassing rate of the carbon fiber array cathode is an order smaller than that of the velvet cathode under similar conditions, which shows that this carbon fiber array cathode is a promising replacement of the velvet cathode in the application of magnetically insulated transmission line oscillators and relativistic magnetrons.

  18. Optimisation of air cooled, open-cathode fuel cells: Current of lowest resistance and electro-thermal performance mapping

    NASA Astrophysics Data System (ADS)

    Meyer, Quentin; Ronaszegi, Krisztian; Pei-June, Gan; Curnick, Oliver; Ashton, Sean; Reisch, Tobias; Adcock, Paul; Shearing, Paul R.; Brett, Daniel J. L.

    2015-09-01

    Selecting the ideal operating point for a fuel cell depends on the application and consequent trade-off between efficiency, power density and various operating considerations. A systematic methodology for determining the optimal operating point for fuel cells is lacking; there is also the need for a single-value metric to describe and compare fuel cell performance. This work shows how the 'current of lowest resistance' can be accurately measured using electrochemical impedance spectroscopy and used as a useful metric of fuel cell performance. This, along with other measures, is then used to generate an 'electro-thermal performance map' of fuel cell operation. A commercial air-cooled open-cathode fuel cell is used to demonstrate how the approach can be used; in this case leading to the identification of the optimum operating temperature of ∼45 °C.

  19. Autonomous, Retrievable, Deep Sea Microbial Fuel Cell

    NASA Astrophysics Data System (ADS)

    Richter, K.

    2014-12-01

    Microbial fuel cells (MFCs) work by providing bacteria in anaerobic sediments with an electron acceptor (anode) that stimulates metabolism of organic matter. The buried anode is connected via control circuitry to a cathode exposed to oxygen in the overlying water. During metabolism, bacteria release hydrogen ions into the sediment and transfer electrons extra-cellularly to the anode, which eventually reduce dissolved oxygen at the cathode, forming water. The open circuit voltage is approximately 0.8 v. The voltage between electrodes is operationally kept at 0.4 v with a potentiastat. The current is chiefly limited by the rate of microbial metabolism at the anode. The Office of Naval Research has encouraged development of microbial fuel cells in the marine environment at a number of academic and naval institutions. Earlier work in shallow sediments of San Diego Bay showed that the most important environmental parameters that control fuel cell power output in San Diego Bay were total organic carbon in the sediment and seasonal water temperature. Current MFC work at SPAWAR includes extension of microbial fuel cell tests to the deep sea environment (>1000 m) and, in parallel, testing microbial fuel cells in the laboratory under deep sea conditions. One question we are asking is whether MFC power output from deep water sediments repressurized and chilled in the laboratory comparable to those measured in situ. If yes, mapping the power potential of deep sea sediments may be made much easier, requiring sediment grabs and lab tests rather than deployment and retrieval of fuel cells. Another question we are asking is whether in situ temperature and total organic carbon in the deep sea sediment can predict MFC power. If yes, then we can make use of the large collection of publicly available, deep sea oceanographic measurements to make these predictions, foregoing expensive work at sea. These regressions will be compared to those derived from shallow water measurements.

  20. Virtual cathode emission of an annular cold cathode

    NASA Astrophysics Data System (ADS)

    Park, S.-d.; Kim, J.-h.; Han, J.; Yoon, M.; Park, S. Y.; Choi, D. W.; Shin, J. W.; So, J. H.

    2009-11-01

    Recent measurement of voltage V and current I of the electron gun of a relativistic klystron amplifier revealed that the resulting current-voltage relationship appeared to differ from the usual Child-Langmuir law (I∝V3/2) especially during the initial period of voltage increase. This paper attempts to explain this deviation by examining the emission mechanism using particle-in-cell simulation. The emission area in the cathode increased stepwise as the applied voltage increased and within each step the current and voltage followed the Child-Langmuir law. The electron emission began when the voltage reached a threshold, and the perveance increased with the emission area. Furthermore, an apparent virtual cathode was formed which was larger than the cathode tip. This occurs because, above a certain voltage, the emission from the edge and the side of the cathode surface dominates the emission from the front-end surface.

  1. Storage battery aspects of air-electrode research

    NASA Astrophysics Data System (ADS)

    Buzelli, E. S.; Berk, L. B.; Demczyk, B. G.; Zuckerbrod, D.

    The use of air electrodes in secondary, alkaline energy storage systems offers several significant advantages over other conventional cathode systems. The oxygen, required for operation, is not stored or carried within the battery system. The weight of the air electrode is significantly lower than alternative cathode couples for the same mission. The cost of the air electrode is potentially low. As a result of these characteristics, alkaline electrolyte energy storage systems with air electrodes have the potential for achieving energy density levels in excess of 150 Whr/kg at low costs, $30-$40/kWh. The primary key to a successful metal-air secondary battery for an EV application is the development of a bifunctinal air electrode. This paper discusses the various aspects of air electrode research for this application, as well as the physical and performance requirements of the air electrode in this advanced technology battery system.

  2. Miniaturized cathodic arc plasma source

    DOEpatents

    Anders, Andre; MacGill, Robert A.

    2003-04-15

    A cathodic arc plasma source has an anode formed of a plurality of spaced baffles which extend beyond the active cathode surface of the cathode. With the open baffle structure of the anode, most macroparticles pass through the gaps between the baffles and reflect off the baffles out of the plasma stream that enters a filter. Thus the anode not only has an electrical function but serves as a prefilter. The cathode has a small diameter, e.g. a rod of about 1/4 inch (6.25 mm) diameter. Thus the plasma source output is well localized, even with cathode spot movement which is limited in area, so that it effectively couples into a miniaturized filter. With a small area cathode, the material eroded from the cathode needs to be replaced to maintain plasma production. Therefore, the source includes a cathode advancement or feed mechanism coupled to cathode rod. The cathode also requires a cooling mechanism. The movable cathode rod is housed in a cooled metal shield or tube which serves as both a current conductor, thus reducing ohmic heat produced in the cathode, and as the heat sink for heat generated at or near the cathode. Cooling of the cathode housing tube is done by contact with coolant at a place remote from the active cathode surface. The source is operated in pulsed mode at relatively high currents, about 1 kA. The high arc current can also be used to operate the magnetic filter. A cathodic arc plasma deposition system using this source can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  3. Cold Cathode Electron Beam Controlled CO2 Laser Performance.

    DTIC Science & Technology

    1974-10-01

    Siegman (ref. 7), the cavity parameters are g, - 3/2, g2 3/4 so that 0he cavity will be confocal when the mirror separation is 2.5 m. The laser output was...E. Siegman , Laser Focus 7, 42, 1971. 8. W. F. Krupke and W. R. Sooy, IEEE Journal Quant. Elec. QE-5, 575, 1969. 9. 0. R. Wood, et al., Appl. Phys...U t AD/A-000 413 COLD CATHODE ELECTRON BEAM CONTROLLED C02 LASER PERFORMANCE Leslie L. McKee, 1II, et al Air Force Weapons Laboratory Kirtland Air

  4. Possibilities for extremophilic microorganisms in microbial electrochemical systems

    PubMed Central

    Dopson, Mark; Ni, Gaofeng; Sleutels, Tom HJA

    2015-01-01

    Microbial electrochemical systems exploit the metabolism of microorganisms to generate electrical energy or a useful product. In the past couple of decades, the application of microbial electrochemical systems has increased from the use of wastewaters to produce electricity to a versatile technology that can use numerous sources for the extraction of electrons on the one hand, while on the other hand these electrons can be used to serve an ever increasing number of functions. Extremophilic microorganisms grow in environments that are hostile to most forms of life and their utilization in microbial electrochemical systems has opened new possibilities to oxidize substrates in the anode and produce novel products in the cathode. For example, extremophiles can be used to oxidize sulfur compounds in acidic pH to remediate wastewaters, generate electrical energy from marine sediment microbial fuel cells at low temperatures, desalinate wastewaters and act as biosensors of low amounts of organic carbon. In this review, we will discuss the recent advances that have been made in using microbial catalysts under extreme conditions and show possible new routes that extremophilic microorganisms open for microbial electrochemical systems. PMID:26474966

  5. Fundamental Investigations and Rational Design of Durable High-Performance SOFC Cathodes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Yu; Ding, Dong; Wei, Tao

    cathodes as well as the cathode/electrolyte interfaces under realistic operating conditions has been studied. It is found that SrO readily segregated/enriched on the LSCF surface. More severe contamination conditions cause more SrO on surface. Novel catalyst coatings through particle depositions (PrOx) or continuous thin films (PNM) were successfully developed to improve the activity and stability of LSCF cathodes. Finally, we have demonstrated enhanced activity and stability of LSCF cathodes over longer periods of time in homemade and commercially available cells by an optimized PNM (dense film and particles) infiltration process, under clean air and realistic operating conditions (3% H 2O, 5% CO 2 and direct Crofer contact). Both performance and durability of single cells with PNM coating has been enhanced compared with those without coating. Raman analysis of cathodes surface indicated that the intensity of SrCrO 4 was significantly decreased.« less

  6. Pressed boride cathodes

    NASA Technical Reports Server (NTRS)

    Wolski, W.

    1985-01-01

    Results of experimental studies of emission cathodes made from lanthanum, yttrium, and gadolinium hexaborides are presented. Maximum thermal emission was obtained from lanthanum hexaboride electrodes. The hexaboride cathodes operated stably under conditions of large current density power draw, at high voltages and poor vacuum. A microtron electron gun with a lanthanum hexaboride cathode is described.

  7. Energy Efficiency and Productivity Enhancement of Microbial Electrosynthesis of Acetate

    PubMed Central

    LaBelle, Edward V.; May, Harold D.

    2017-01-01

    It was hypothesized that a lack of acetogenic biomass (biocatalyst) at the cathode of a microbial electrosynthesis system, due to electron and nutrient limitations, has prevented further improvement in acetate productivity and efficiency. In order to increase the biomass at the cathode and thereby performance, a bioelectrochemical system with this acetogenic community was operated under galvanostatic control and continuous media flow through a reticulated vitreous carbon (RVC) foam cathode. The combination of galvanostatic control and the high surface area cathode reduced the electron limitation and the continuous flow overcame the nutrient limitation while avoiding the accumulation of products and potential inhibitors. These conditions were set with the intention of operating the biocathode through the production of H2. Biofilm growth occurred on and within the unmodified RVC foam regardless of vigorous H2 generation on the cathode surface. A maximum volumetric rate or space time yield for acetate production of 0.78 g/Lcatholyte/h was achieved with 8 A/Lcatholyte (83.3 A/m2projected surface area of cathode) supplied to the continuous flow/culture bioelectrochemical reactors. The total Coulombic efficiency in H2 and acetate ranged from approximately 80–100%, with a maximum of 35% in acetate. The overall energy efficiency ranged from approximately 35–42% with a maximum to acetate of 12%. PMID:28515713

  8. Energy Efficiency and Productivity Enhancement of Microbial Electrosynthesis of Acetate.

    PubMed

    LaBelle, Edward V; May, Harold D

    2017-01-01

    It was hypothesized that a lack of acetogenic biomass (biocatalyst) at the cathode of a microbial electrosynthesis system, due to electron and nutrient limitations, has prevented further improvement in acetate productivity and efficiency. In order to increase the biomass at the cathode and thereby performance, a bioelectrochemical system with this acetogenic community was operated under galvanostatic control and continuous media flow through a reticulated vitreous carbon (RVC) foam cathode. The combination of galvanostatic control and the high surface area cathode reduced the electron limitation and the continuous flow overcame the nutrient limitation while avoiding the accumulation of products and potential inhibitors. These conditions were set with the intention of operating the biocathode through the production of H 2 . Biofilm growth occurred on and within the unmodified RVC foam regardless of vigorous H 2 generation on the cathode surface. A maximum volumetric rate or space time yield for acetate production of 0.78 g/L catholyte /h was achieved with 8 A/L catholyte (83.3 A/m 2 projected surface area of cathode) supplied to the continuous flow/culture bioelectrochemical reactors. The total Coulombic efficiency in H 2 and acetate ranged from approximately 80-100%, with a maximum of 35% in acetate. The overall energy efficiency ranged from approximately 35-42% with a maximum to acetate of 12%.

  9. Surface-oxidized cobalt phosphide used as high efficient electrocatalyst in activated carbon air-cathode microbial fuel cell

    NASA Astrophysics Data System (ADS)

    Yang, Tingting; Wang, Zhong; Li, Kexun; Liu, Yi; Liu, Di; Wang, Junjie

    2017-09-01

    Herein, we report a simplistic method to fabricate the surface-oxidized cobalt phosphide (CoP) nanocrystals (NCs), which is used as electrocatalyst for oxygen reduction reaction (ORR) in microbial fuel cell (MFC) for the first time. The corallite-like CoP NCs are successfully prepared by a hydrothermal reaction following a phosphating treatment in N2 atmosphere. When used as an ORR catalyst, cobalt phosphide shows comparable onset potential, inferior resistance, as well as a small Tafel slope with long-term stability in neutral media. The maximum power density of MFC embellished with 10% CoP reached 1914.4 ± 59.7 mW m-2, which is 108.5% higher than the control. The four-electron pathway, observed by the RDE, plays a crucial role in electrochemical catalytic activity. In addition, material characterizations indicate that the surface oxide layer (CoOx) around the metallic CoP core is important and beneficial for ORR. Accordingly, it can be expected that the as-synthesized CoP will be a promising candidate of the non-precious metal ORR electrocatalysts for electrochemical energy applications.

  10. Microbial fuel cell treatment of ethanol fermentation process water

    DOEpatents

    Borole, Abhijeet P [Knoxville, TN

    2012-06-05

    The present invention relates to a method for removing inhibitor compounds from a cellulosic biomass-to-ethanol process which includes a pretreatment step of raw cellulosic biomass material and the production of fermentation process water after production and removal of ethanol from a fermentation step, the method comprising contacting said fermentation process water with an anode of a microbial fuel cell, said anode containing microbes thereon which oxidatively degrade one or more of said inhibitor compounds while producing electrical energy or hydrogen from said oxidative degradation, and wherein said anode is in electrical communication with a cathode, and a porous material (such as a porous or cation-permeable membrane) separates said anode and cathode.

  11. Influence of diligent disintegration on anaerobic biomass and performance of microbial fuel cell.

    PubMed

    Divyalakshmi, Palanisamy; Murugan, Devaraj; Rai, Chockalingam Lajapathi

    2017-12-01

    To enhance the performance of microbial fuel cells (MFC) by increasing the surface area of cathode and diligent mechanical disintegration of anaerobic biomass. Tannery effluent and anaerobic biomass were used. The increase in surface area of the cathode resulted in 78% COD removal, with the potential, current density, power density and coulombic efficiency of 675 mV, 147 mA m -2 , 33 mW m -2 and 3.5%, respectively. The work coupled with increased surface area of the cathode with diligent mechanical disintegration of the biomass, led to a further increase in COD removal of 82% with the potential, current density, power density and coulombic efficiency of 748 mV, 229 mA m -2 , 78 mW m -2 and 6% respectively. Mechanical disintegration of the biomass along with increased surface area of cathode enhances power generation in vertical MFC reactors using tannery effluent as fuel.

  12. Supercapacitive microbial fuel cell: Characterization and analysis for improved charge storage/delivery performance.

    PubMed

    Houghton, Jeremiah; Santoro, Carlo; Soavi, Francesca; Serov, Alexey; Ieropoulos, Ioannis; Arbizzani, Catia; Atanassov, Plamen

    2016-10-01

    Supercapacitive microbial fuel cells with various anode and cathode dimensions were investigated in order to determine the effect on cell capacitance and delivered power quality. The cathode size was shown to be the limiting component of the system in contrast to anode size. By doubling the cathode area, the peak power output was improved by roughly 120% for a 10ms pulse discharge and internal resistance of the cell was decreased by ∼47%. A model was constructed in order to predict the performance of a hypothetical cylindrical MFC design with larger relative cathode size. It was found that a small device based on conventional materials with a volume of approximately 21cm(3) would be capable of delivering a peak power output of approximately 25mW at 70mA, corresponding to ∼1300Wm(-3). Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  13. Microbial fuel cells for direct electrical energy recovery from urban wastewaters.

    PubMed

    Capodaglio, A G; Molognoni, D; Dallago, E; Liberale, A; Cella, R; Longoni, P; Pantaleoni, L

    2013-01-01

    Application of microbial fuel cells (MFCs) to wastewater treatment for direct recovery of electric energy appears to provide a potentially attractive alternative to traditional treatment processes, in an optic of costs reduction, and tapping of sustainable energy sources that characterizes current trends in technology. This work focuses on a laboratory-scale, air-cathode, and single-chamber MFC, with internal volume of 6.9 L, operating in batch mode. The MFC was fed with different types of substrates. This study evaluates the MFC behaviour, in terms of organic matter removal efficiency, which reached 86% (on average) with a hydraulic retention time of 150 hours. The MFC produced an average power density of 13.2 mW/m(3), with a Coulombic efficiency ranging from 0.8 to 1.9%. The amount of data collected allowed an accurate analysis of the repeatability of MFC electrochemical behaviour, with regards to both COD removal kinetics and electric energy production.

  14. Storage battery aspects of air-electrode research

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Buzzelli, E.S.; Berk, L.B.; Demczyk, B.G.

    1983-08-01

    The use of air electrodes in secondary, alkaline energy storage systems offers several significant advantages over other conventional cathode systems. The oxygen, required for operation, is not stored or carried within the battery system. The weight of the air electrode is significantly lower than alternative cathode couples for the same mission. The cost of the air electrode is potentially low. As a result of these characteristics, alkaline electrolyte energy storage systems with air electrodes have the potential for achieving energy density levels in excess of 150 Whr/kg at low costs, $30-$40/kWh. The primary key to a successful metal-air secondary batterymore » for an EV application is the development of a bifunctional air electrode. This paper discusses the various aspects of air electrode research for this application, as well as the physical and performance requirements of the air electrode in this advanced technology battery system.« less

  15. Stainless steel in coastal seawater: sunlight counteracts biologically enhanced cathodic kinetics.

    PubMed

    Eashwar, M; Lakshman Kumar, A; Sreedhar, G; Kennedy, J; Suresh Bapu, R H

    2014-09-01

    The influence of sunlight of varying intensity on the performance of UNS S30400 stainless steel (SS) was explored under conditions of natural biofilm development in coastal seawater. In a series of tests performed outdoors under an opaque roof, a range of shades were fashioned to impart varied amounts of diurnal light. These were an ambient level where the underwater illumination was ~ 5% of full sunlight, two intermediate ranges of lighting with ~ 2.5% and ~ 1% of the daylight, and a condition of full darkness. In comparison with the dark, increments of sunlight rendered the SS progressively less aggressive as cathodes in galvanic couples with UNS C70600 alloy. Likewise, welded SS with pre-initiated localized corrosion sites exhibited substantially lower rates of propagation with light. Thus, biofilms and sunlight affected cathodic kinetics in opposite ways. Surface analytical tests showed that the accumulation of manganese (Mn) within the biofilms was small relative to reports from waters of lower salinity. These results not only reveal that extremely low amounts of sunlight are adequate to offset the microbial effect, but also highlight the lack of convincing evidence for Mn cycling as a potent mechanism for enhanced cathodic kinetics in full-strength seawater.

  16. [Detection of toxic substances in microbial fuel cells].

    PubMed

    Wang, Jiefu; Niu, Hao; Wu, Wenguo

    2017-05-25

    Microbial fuel cells (MFCs) is a highly promising bioelectrochemical technology and uses microorganisms as catalyst to convert chemical energy directly to electrical energy. Microorganisms in the anodic chamber of MFC oxidize the substrate and generate electrons. The electrons are absorbed by the anode and transported through an external circuit to the cathode for corresponding reduction. The flow of electrons is measured as current. This current is a linear measure of the activity of microorganisms. If a toxic event occurs, microbial activity will change, most likely decrease. Hence, fewer electrons are transported and current decreases as well. In this way, a microbial fuel cell-based biosensor provides a direct measure to detect toxicity for samples. This paper introduces the detection of antibiotics, heavy metals, organic pollutants and acid in MFCs. The existing problems and future application of MFCs are also analyzed.

  17. Air breathing direct methanol fuel cell

    DOEpatents

    Ren, Xiaoming

    2002-01-01

    An air breathing direct methanol fuel cell is provided with a membrane electrode assembly, a conductive anode assembly that is permeable to air and directly open to atmospheric air, and a conductive cathode assembly that is permeable to methanol and directly contacting a liquid methanol source.

  18. Coating of porous carbon for use in lithium air batteries

    DOEpatents

    Amine, Khalil; Lu, Jun; Du, Peng; Lei, Yu; Elam, Jeffrey W

    2015-04-14

    A cathode includes a carbon material having a surface, the surface having a first thin layer of an inert material and a first catalyst overlaying the first thin layer, the first catalyst including metal or metal oxide nanoparticles, wherein the cathode is configured for use as the cathode of a lithium-air battery.

  19. Processes For Cleaning a Cathode Tube and Assemblies In A Hollow Cathode Assembly

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J. (Inventor); Verhey, Timothy R. R. (Inventor); Soulas, George C. (Inventor)

    2001-01-01

    The present invention is a process for cleaning a cathode tube and other subassemblies in a hollow cathode assembly. In the disclosed process, hand covering elastomer gloves are used for handling all cathode assembly parts. The cathode tube and other subassemblies are cleaned with a lint-free cloth damped with acetone, then wiped with alcohol, immersed in ethyl alcohol or acetone, and ultrasonic agitation is applied, heating to 60 C. for ethyl alcohol or 56 C. for acetone. The cathode tube and other subassemblies are dried by blowing with nitrogen gas.

  20. Improved performance of single-chamber microbial fuel cells through control of membrane deformation.

    PubMed

    Zhang, Xiaoyuan; Cheng, Shaoan; Huang, Xia; Logan, Bruce E

    2010-03-15

    Cation (CEMs) and anion exchange membrane (AEMs) are commonly used in microbial fuel cells (MFCs) to enhance Coulombic efficiencies (CEs) by reducing the flux of oxygen through the cathode to bacteria on the anode. AEMs typically work better than CEMs, but in initial experiments we observed the opposite using a membrane electrode assembly MFC. The reason was identified to be membrane deformation, which resulted in water and gas trapped between the membrane and cathode. To correct this, stainless steel mesh was used to press the membrane flat against the cathode. With the steel mesh, AEM performance increased to 46+/-4 W/m(3) in a single cathode MFC, and 98+/-14 W/m(3) in a double-cathode MFC. These power densities were higher than those using a CEM of 32+/-2 W/m(3) (single cathode) and 63+/-6 W/m(3) (double cathode). Higher pH gradients across the membrane and salt precipitation on the cathode were responsible for the reduced performance of the CEM compared to the AEM. CEs reached over 90% for both membranes at >2A/m(2). These results demonstrate the importance of avoiding water accumulation in thin films between membranes and electrodes, and explain additional reasons for poorer performance of CEMs compared to AEMs. (c) 2009 Elsevier B.V. All rights reserved.

  1. Metabolic Reconstruction and Modeling Microbial Electrosynthesis.

    PubMed

    Marshall, Christopher W; Ross, Daniel E; Handley, Kim M; Weisenhorn, Pamela B; Edirisinghe, Janaka N; Henry, Christopher S; Gilbert, Jack A; May, Harold D; Norman, R Sean

    2017-08-21

    Microbial electrosynthesis is a renewable energy and chemical production platform that relies on microbial cells to capture electrons from a cathode and fix carbon. Yet despite the promise of this technology, the metabolic capacity of the microbes that inhabit the electrode surface and catalyze electron transfer in these systems remains largely unknown. We assembled thirteen draft genomes from a microbial electrosynthesis system producing primarily acetate from carbon dioxide, and their transcriptional activity was mapped to genomes from cells on the electrode surface and in the supernatant. This allowed us to create a metabolic model of the predominant community members belonging to Acetobacterium, Sulfurospirillum, and Desulfovibrio. According to the model, the Acetobacterium was the primary carbon fixer, and a keystone member of the community. Transcripts of soluble hydrogenases and ferredoxins from Acetobacterium and hydrogenases, formate dehydrogenase, and cytochromes of Desulfovibrio were found in high abundance near the electrode surface. Cytochrome c oxidases of facultative members of the community were highly expressed in the supernatant despite completely sealed reactors and constant flushing with anaerobic gases. These molecular discoveries and metabolic modeling now serve as a foundation for future examination and development of electrosynthetic microbial communities.

  2. Electricity generation and modeling of microbial fuel cell from continuous beer brewery wastewater.

    PubMed

    Wen, Qing; Wu, Ying; Cao, Dianxue; Zhao, Lixin; Sun, Qian

    2009-09-01

    Electricity production and modeling of microbial fuel cell (MFC) from continuous beer brewery wastewater was studied in this paper. A single air-cathode MFC was constructed, carbon fiber was used as anode and diluted brewery wastewater (COD=626.58 mg/L) as substrate. The MFC displayed an open-circuit voltage of 0.578 V and a maximum power density of 9.52 W/m(3) (264 mW/m(2)). Using the model based on polarization curve, various voltage losses were quantified. At current density of 1.79 A/m(2), reaction kinetic loss and mass transport loss both achieved to 0.248 V; while ohmic loss was 0.046 V. Results demonstrated that it was feasible and stable for producing bioelectricity from brewery wastewater; while the most important factors which influenced the performance of the MFC are reaction kinetic loss and mass transport loss.

  3. Aqueous lithium air batteries

    DOEpatents

    Visco, Steven J.; Nimon, Yevgeniy S.; De Jonghe, Lutgard C.; Petrov, Alexei; Goncharenko, Nikolay

    2017-05-23

    Aqueous Li/Air secondary battery cells are configurable to achieve high energy density and prolonged cycle life. The cells include a protected a lithium metal or alloy anode and an aqueous catholyte in a cathode compartment. The aqueous catholyte comprises an evaporative-loss resistant and/or polyprotic active compound or active agent that partakes in the discharge reaction and effectuates cathode capacity for discharge in the acidic region. This leads to improved performance including one or more of increased specific energy, improved stability on open circuit, and prolonged cycle life, as well as various methods, including a method of operating an aqueous Li/Air cell to simultaneously achieve improved energy density and prolonged cycle life.

  4. Microbial-enzymatic-hybrid biological fuel cell with optimized growth conditions for Shewanella oneidensis DSP-10.

    PubMed

    Roy, Jared N; Luckarift, Heather R; Sizemore, Susan R; Farrington, Karen E; Lau, Carolin; Johnson, Glenn R; Atanassov, Plamen

    2013-07-10

    In this work we present a biological fuel cell fabricated by combining a Shewanella oneidensis microbial anode and a laccase-modified air-breathing cathode. This concept is devised as an extension to traditional biochemical methods by incorporating diverse biological catalysts with the aim of powering small devices. In preparing the biological fuel cell anode, novel hierarchical-structured architectures and biofilm configurations were investigated. A method for creating an artificial biofilm based on encapsulating microorganisms in a porous, thin film of silica was compared with S. oneidensis biofilms that were allowed to colonize naturally. Results indicate comparable current and power densities for artificial and natural biofilm formations, based on growth characteristics. As a result, this work describes methods for creating controllable and reproducible bio-anodes and demonstrates the versatility of hybrid biological fuel cells. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Application of gas diffusion biocathode in microbial electrosynthesis from carbon dioxide.

    PubMed

    Bajracharya, Suman; Vanbroekhoven, Karolien; Buisman, Cees J N; Pant, Deepak; Strik, David P B T B

    2016-11-01

    Microbial catalysis of carbon dioxide (CO 2 ) reduction to multi-carbon compounds at the cathode is a highly attractive application of microbial electrosynthesis (MES). The microbes reduce CO 2 by either taking the electrons or reducing the equivalents produced at the cathode. While using gaseous CO 2 as the carbon source, the biological reduction process depends on the dissolution and mass transfer of CO 2 in the electrolyte. In order to deal with this issue, a gas diffusion electrode (GDE) was investigated by feeding CO 2 through the GDE into the MES reactor for its reduction at the biocathode. A combination of the catalyst layer (porous activated carbon and Teflon binder) and the hydrophobic gas diffusion layer (GDL) creates a three-phase interface at the electrode. So, CO 2 and reducing equivalents will be available to the biocatalyst on the cathode surface. An enriched inoculum consisting of acetogenic bacteria, prepared from an anaerobic sludge, was used as a biocatalyst. The cathode potential was maintained at -1.1 V vs Ag/AgCl to facilitate direct and/or hydrogen-mediated CO 2 reduction. Bioelectrochemical CO 2 reduction mainly produced acetate but also extended the products to ethanol and butyrate. Average acetate production rates of 32 and 61 mg/L/day, respectively, with 20 and 80 % CO 2 gas mixture feed were achieved with 10 cm 2 of GDE. The maximum acetate production rate remained 238 mg/L/day for 20 % CO 2 gas mixture. In conclusion, a gas diffusion biocathode supported bioelectrochemical CO 2 reduction with enhanced mass transfer rate at continuous supply of gaseous CO 2 . Graphical abstract ᅟ.

  6. Turning Waste Chemicals into Wealth-A New Approach To Synthesize Efficient Cathode Material for an Li-O2 Battery.

    PubMed

    Yao, Ying; Wu, Feng

    2017-09-20

    An Li-O 2 battery requires the oxygen-breathing cathode to be highly electronically conductive, rapidly oxygen diffusive, structurally stable, and often times electrocatalytically active. Catalyst-decorated porous carbonaceous materials are the chosen air cathode in this regard. Alternatively, biomass-derived carbonaceous materials possess great ability to remove heavy and toxic metal ions from waste, forming a metal-adsorbed porous carbonaceous material. The similar structure between the air cathode and the metal-adsorbed biomass-derived carbon nicely bridges these two irrelevant areas. In this study, we investigated the electrochemical activity of a biochar material Ag-ESB directly synthesized from ethanol sludge residue in a rechargeable aprotic Li-O 2 battery. Ag ions were adsorbed from sewage and became Ag nanoparticles with uniform coverage on the biochar surface. The as-prepared material exhibits good electrochemical behavior in battery testing, especially toward the battery efficiency and cyclability. This study provides the possibility of synthetically efficient cathode material by reusing "waste" such as biofuel sludge residue. It is an economically and environmentally friendly approach both for an energy-storage system and for waste recycling.

  7. Requirements for long-life operation of inert gas hollow cathodes: Preliminary report

    NASA Technical Reports Server (NTRS)

    Verhey, Timothy R.; Macrae, Gregory S.

    1990-01-01

    An experimental investigation was initiated to establish conditioning procedures for reliable hollow cathode operation via the characterization of critical parameters in a representative cathode test facility. From vacuum pumpdown rates, it was found that approximately 1.5 hours were required to achieve pressure levels within 5 percent of the lowest attainable pressure for this facility, depending on the purge conditions. The facility atmosphere was determined by a residual gas analyzer to be composed of primarily air and water vapor. The effects of vacuum pumping and inert gas purging were evaluated. A maximum effective leakage rate of 2.0 x 10(exp -3)sccm was observed and its probable causes were examined. An extended test of a 0.64 cm diameter Mo-Re hollow cathode was successfully completed. This test ran for 504 hours at an emission current of 23.0 amperes and a xenon flow rate of 6.1 sccm. Discharge voltage rose continuously from 15 to 21 volts over the course of the test. The temperature of the cathode body during the test was relatively stable at 1160 C. Post-test examination revealed ion-bombardment texturing of the orifice plate to be the only detectable sign of wear on the hollow cathode.

  8. Microbial fuel cell treatment of fuel process wastewater

    DOEpatents

    Borole, Abhijeet P; Tsouris, Constantino

    2013-12-03

    The present invention is directed to a method for cleansing fuel processing effluent containing carbonaceous compounds and inorganic salts, the method comprising contacting the fuel processing effluent with an anode of a microbial fuel ell, the anode containing microbes thereon which oxidatively degrade one or more of the carbonaceous compounds while producing electrical energy from the oxidative degradation, and directing the produced electrical energy to drive an electrosorption mechanism that operates to reduce the concentration of one or more inorganic salts in the fuel processing effluent, wherein the anode is in electrical communication with a cathode of the microbial fuel cell. The invention is also directed to an apparatus for practicing the method.

  9. Microbial Photoelectrosynthesis for Self-Sustaining Hydrogen Generation.

    PubMed

    Lu, Lu; Williams, Nicholas B; Turner, John A; Maness, Pin-Ching; Gu, Jing; Ren, Zhiyong Jason

    2017-11-21

    Current artificial photosynthesis (APS) systems are promising for the storage of solar energy via transportable and storable fuels, but the anodic half-reaction of water oxidation is an energy intensive process which in many cases poorly couples with the cathodic half-reaction. Here we demonstrate a self-sustaining microbial photoelectrosynthesis (MPES) system that pairs microbial electrochemical oxidation with photoelectrochemical water reduction for energy efficient H 2 generation. MPES reduces the overall energy requirements thereby greatly expanding the range of semiconductors that can be utilized in APS. Due to the recovery of chemical energy from waste organics by the mild microbial process and utilization of cost-effective and stable catalyst/electrode materials, our MPES system produced a stable current of 0.4 mA/cm 2 for 24 h without any external bias and ∼10 mA/cm 2 with a modest bias under one sun illumination. This system also showed other merits, such as creating benefits of wastewater treatment and facile preparation and scalability.

  10. Comparative performances of microbial capacitive deionization cell and microbial fuel cell fed with produced water from the Bakken shale.

    PubMed

    Shrestha, Namita; Chilkoor, Govinda; Wilder, Joseph; Ren, Zhiyong Jason; Gadhamshetty, Venkataramana

    2018-06-01

    This study evaluates and compares the performance of microbial fuel cells (MFCs) and microbial capacitive deionization cells (MCDCs) fed with wastewater produced from the Bakken shale. The produced water was characterized by high levels of dissolved solids and chemical oxygen demand (COD). Two-compartment MFCs and three-compartment MCDCs were evaluated under batch-fed mode using mixed microbial consortia in the anode, ferricyanide in the cathode, and produced water as the electrolyte in the anode and capacitive deionization units. COD removal in the MFCs was 88%, while that in the MCDCs was limited to 76%. The lower performance of the MCDCs was due to the large impedance (6600 Ω cm 2 ) compared with the MFCs (870 Ω cm 2 ). However, the MCDCs achieved two-fold higher removal of dissolved solids. Both the MFCs and MCDCs suffered from a higher impedance induced by fouling in the latter stages of the operation. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Simultaneous carbon and nitrogen removal using a litre-scale upflow microbial fuel cell.

    PubMed

    Zhao, Ling-ling; Song, Tian-shun

    2014-01-01

    A 10 L upflow microbial fuel cell (UMFC) was constructed for simultaneous carbon and nitrogen removal. During the 6-month operation, the UMFC constantly removed carbon and nitrogen, and then generated electricity with synthetic wastewater as substrate. At 5.0 mg L(-1) dissolved oxygen, 100 Ω external resistance, and pH 6.5, the maximum power density (Pmax) and nitrification rate for the UMFC was 19.5 mW m(-2) and 17.9 mg·(L d)(-1), respectively. In addition, Pmax in the UMFC with chicken manure wastewater as substrate was 16 mW m(-2), and a high chemical oxygen demand (COD) removal efficiency of 94.1% in the UMFC was achieved at 50 mM phosphate-buffered saline. Almost all ammonia in the cathode effluent was effectively degraded after biological denitrification in the UMFC cathode. The results can help to further develop pilot-scale microbial fuel cells for simultaneous carbon and nitrogen removal.

  12. Cathode materials review

    NASA Astrophysics Data System (ADS)

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

    2014-06-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  13. Comparison of electrochemical performances and microbial community structures of two photosynthetic microbial fuel cells.

    PubMed

    Zheng, Wei; Cai, Teng; Huang, Manhong; Chen, Donghui

    2017-11-01

    Microbial fuel cells (MFCs) have attracted intensive interest for their power generation and pollutants removal characteristics. Electrochemical performances and community structures of two algae cathode photosynthetic MFCs were investigated and compared. Microbial consortia of these two MFCs were taken from wetland sediment (named SMFC) and an up-flow anaerobic wastewater treatment reactor (named UMFC). Maximum power density of the SMFC and UMFC achieved 202.9 ± 18.1 mW/m 2 and 158.2±15.1 mW/m 2 , respectively. The SMFC displayed higher columbic efficiency but lower chemical oxygen demand (COD) removal efficiency than that of UMFC. The results also revealed the addition of riboflavin (RF) and neutral red (NR) decreased the redox current of the SMFC but promoted that of UMFC. Community structure analysis showed the SMFC was dominated by photosynthetic genus Rhodopseudomonas (61.25%), while bacterial genera in the UMFC were more evenly distributed. The difference of electrochemical activities of the two MFCs was caused by the different roles of exoelectrogens such as Rhodopseudomonas spp. and Citrobacter spp. in the electron transfer process. Newly developed photosynthetic microbial fuel cells (PMFCs) provide a suitable process to generate power and remove pollutants. The consortia have a significant role in the performance and microbial community of the system. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  14. Carbon Dioxide Addition to Microbial Fuel Cell Cathodes Maintains Sustainable Catholyte pH and Improves Anolyte pH, Alkalinity, and Conductivity

    USDA-ARS?s Scientific Manuscript database

    Bioelectrochemical system (BES) pH imbalances develop due to anodic proton-generating oxidation reactions and cathodic hydroxide-ion-generating reduction reactions. Until now, workers added unsustainable buffers to reduce the pH difference between the anode and cathode because the pH imbalance cont...

  15. Magnetic-cusp, cathodic-arc source

    DOEpatents

    Falabella, S.

    1995-11-21

    A magnetic-cusp for a cathodic-arc source wherein the arc is confined to the desired cathode surface, provides a current path for electrons from the cathode to the anode, and utilizes electric and magnetic fields to guide ions from the cathode to a point of use, such as substrates to be coated. The magnetic-cusp insures arc stability by an easy magnetic path from anode to cathode, while the straight-through arrangement leads to high ion transmission. 3 figs.

  16. Arcjet Cathode Phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  17. Arcjet cathode phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  18. Cathode materials review

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Daniel, Claus, E-mail: danielc@ornl.gov; Mohanty, Debasish, E-mail: danielc@ornl.gov; Li, Jianlin, E-mail: danielc@ornl.gov

    2014-06-16

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V andmore » later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO{sub 2} cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.« less

  19. Microbial denitrogenation of fossil fuels.

    PubMed

    Benedik, M J; Gibbs, P R; Riddle, R R; Willson, R C

    1998-09-01

    The microbial degradation of nitrogen compounds from fossil fuels is important because of the contribution these contaminants make to the formation of nitrogen oxides (NOx) and hence to air pollution and acid rain. They also contribute to catalyst poisoning during the refining of crude oil, thus reducing process yields. We review the current status of microbial degradation of aromatic nitrogen compounds and discuss the potential of microbial processes to alleviate these problems.

  20. RuO2 nanoparticles decorated MnOOH/C as effective bifunctional electrocatalysts for lithium-air battery cathodes with long-cycling stability

    NASA Astrophysics Data System (ADS)

    Kim, Gil-Pyo; Lim, Dongwook; Park, Inyeong; Park, Hyelee; Shim, Sang Eun; Baeck, Sung-Hyeon

    2016-08-01

    Manganite (MnOOH) is one of the most effective electrocatalysts for oxygen reduction reaction (ORR), and RuO2 nanoparticles exhibit high activity for oxygen evolution reaction (OER). We herein report a facile means of producing well dispersed RuO2/MnOOH on Ketjen black (RuO2/MnOOH/C) as a bifunctional catalyst for lithium-air (Li-air) batteries. RuO2/MnOOH/C was simply synthesized using a hydrothermal/precipitation based method, and was used as a cathode for a Li-air battery using a Swagelok-type cell. The importance of dispersing active catalysts on a carbon support was clearly demonstrated by textural, charge-discharge voltammetric, and electrochemical impedance spectroscopic (EIS) analyses, comparing results with a catalyst produced by physically mixing RuO2/MnOOH with carbon (RuO2/MnOOH + C). RuO2/MnOOH/C showed low overpotential and stable cycleability up to 170th cycles with 1000 mAh g-1 of charge-discharge capacity, which was attributed to its enhanced active surface area and low charge-transfer resistance. The results obtained suggest that this strategy can be widely applied to bifunctional electrocatalysis, such as secondary batteries and regenerative fuel cell (RFC).

  1. Microbial Community Analysis of a Methane-Producing Biocathode in a Bioelectrochemical System

    PubMed Central

    Van Eerten-Jansen, Mieke C. A. A.; Veldhoen, Anna B.; Plugge, Caroline M.; Stams, Alfons J. M.; Buisman, Cees J. N.

    2013-01-01

    A methane-producing biocathode that converts CO2 into methane was studied electrochemically and microbiologically. The biocathode produced methane at a maximum rate of 5.1 L CH4/m2 projected cathode per day (1.6 A/m2) at −0.7 V versus NHE cathode potential and 3.0 L CH4/m2 projected cathode per day (0.9 A/m2) at −0.6 V versus NHE cathode potential. The microbial community at the biocathode was dominated by three phylotypes of Archaea and six phylotypes of bacteria. The Archaeal phylotypes were most closely related to Methanobacterium palustre and Methanobacterium aarhusense. Besides methanogenic Archaea, bacteria seemed to be associated with methane production, producing hydrogen as an intermediate. Biomass density varied greatly with part of the carbon electrode covered with a dense biofilm, while only clusters of cells were found on other parts. Based on our results, we discuss how inoculum enrichment and changing operational conditions may help to increase biomass density and to select for microorganisms that produce methane. PMID:24187516

  2. Remote control for anode-cathode adjustment

    DOEpatents

    Roose, Lars D.

    1991-01-01

    An apparatus for remotely adjusting the anode-cathode gap in a pulse power machine has an electric motor located within a hollow cathode inside the vacuum chamber of the pulse power machine. Input information for controlling the motor for adjusting the anode-cathode gap is fed into the apparatus using optical waveguides. The motor, controlled by the input information, drives a worm gear that moves a cathode tip. When the motor drives in one rotational direction, the cathode is moved toward the anode and the size of the anode-cathode gap is diminished. When the motor drives in the other direction, the cathode is moved away from the anode and the size of the anode-cathode gap is increased. The motor is powered by batteries housed in the hollow cathode. The batteries may be rechargeable, and they may be recharged by a photovoltaic cell in combination with an optical waveguide that receives recharging energy from outside the hollow cathode. Alternatively, the anode-cathode gap can be remotely adjusted by a manually-turned handle connected to mechanical linkage which is connected to a jack assembly. The jack assembly converts rotational motion of the handle and mechanical linkage to linear motion of the cathode moving toward or away from the anode.

  3. Evaluation on direct interspecies electron transfer in anaerobic sludge digestion of microbial electrolysis cell.

    PubMed

    Zhao, Zisheng; Zhang, Yaobin; Quan, Xie; Zhao, Huimin

    2016-01-01

    Increase of methanogenesis in methane-producing microbial electrolysis cells (MECs) is frequently believed as a result of cathodic reduction of CO2. Recent studies indicated that this electromethanogenesis only accounted for a little part of methane production during anaerobic sludge digestion. Instead, direct interspecies electron transfer (DIET) possibly plays an important role in methane production. In this study, anaerobic digestion of sludge were investigated in a single-chamber MEC reactor, a carbon-felt supplemented reactor and a common anaerobic reactor to evaluate the effects of DIET on the sludge digestion. The results showed that adding carbon felt into the reactor increased 12.9% of methane production and 17.2% of sludge reduction. Imposing a voltage on the carbon felt further improved the digestion. Current calculation showed that the cathodic reduction only contributed to 27.5% of increased methane production. Microbial analysis indicated that DIET played an important role in the anaerobic sludge digestion in the MEC. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Phenol-degrading anode biofilm with high coulombic efficiency in graphite electrodes microbial fuel cell.

    PubMed

    Zhang, Dongdong; Li, Zhiling; Zhang, Chunfang; Zhou, Xue; Xiao, Zhixing; Awata, Takanori; Katayama, Arata

    2017-03-01

    A microbial fuel cell (MFC), with graphite electrodes as both the anode and cathode, was operated with a soil-free anaerobic consortium for phenol degradation. This phenol-degrading MFC showed high efficiency with a current density of 120 mA/m 2 and a coulombic efficiency of 22.7%, despite the lack of a platinum catalyst cathode and inoculation of sediment/soil. Removal of planktonic bacteria by renewing the anaerobic medium did not decrease the performance, suggesting that the phenol-degrading MFC was not maintained by the planktonic bacteria but by the microorganisms in the anode biofilm. Cyclic voltammetry analysis of the anode biofilm showed distinct oxidation and reduction peaks. Analysis of the microbial community structure of the anode biofilm and the planktonic bacteria based on 16S rRNA gene sequences suggested that Geobacter sp. was the phenol degrader in the anode biofilm and was responsible for current generation. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  5. Metabolic Reconstruction and Modeling Microbial Electrosynthesis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marshall, Christopher W.; Ross, Daniel E.; Handley, Kim M.

    Microbial electrosynthesis is a renewable energy and chemical production platform that relies on microbial cells to capture electrons from a cathode and fix carbon. Yet despite the promise of this technology, the metabolic capacity of the microbes that inhabit the electrode surface and catalyze electron transfer in these systems remains largely unknown. Here, we assembled thirteen draft genomes from a microbial electrosynthesis system producing primarily acetate from carbon dioxide, and their transcriptional activity was mapped to genomes from cells on the electrode surface and in the supernatant. This allowed us to create a metabolic model of the predominant community membersmore » belonging to Acetobacterium, Sulfurospirillum, and Desulfovibrio. According to the model, the Acetobacterium was the primary carbon fixer, and a keystone member of the community. Transcripts of soluble hydrogenases and ferredoxins from Acetobacterium and hydrogenases, formate dehydrogenase, and cytochromes of Desulfovibrio were found in high abundance near the electrode surface. Cytochrome c oxidases of facultative members of the community were highly expressed in the supernatant despite completely sealed reactors and constant flushing with anaerobic gases. The resulting molecular discoveries and metabolic modeling now serve as a foundation for future examination and development of electrosynthetic microbial communities.« less

  6. Metabolic Reconstruction and Modeling Microbial Electrosynthesis

    DOE PAGES

    Marshall, Christopher W.; Ross, Daniel E.; Handley, Kim M.; ...

    2017-08-21

    Microbial electrosynthesis is a renewable energy and chemical production platform that relies on microbial cells to capture electrons from a cathode and fix carbon. Yet despite the promise of this technology, the metabolic capacity of the microbes that inhabit the electrode surface and catalyze electron transfer in these systems remains largely unknown. Here, we assembled thirteen draft genomes from a microbial electrosynthesis system producing primarily acetate from carbon dioxide, and their transcriptional activity was mapped to genomes from cells on the electrode surface and in the supernatant. This allowed us to create a metabolic model of the predominant community membersmore » belonging to Acetobacterium, Sulfurospirillum, and Desulfovibrio. According to the model, the Acetobacterium was the primary carbon fixer, and a keystone member of the community. Transcripts of soluble hydrogenases and ferredoxins from Acetobacterium and hydrogenases, formate dehydrogenase, and cytochromes of Desulfovibrio were found in high abundance near the electrode surface. Cytochrome c oxidases of facultative members of the community were highly expressed in the supernatant despite completely sealed reactors and constant flushing with anaerobic gases. The resulting molecular discoveries and metabolic modeling now serve as a foundation for future examination and development of electrosynthetic microbial communities.« less

  7. Enriching Metal-Oxidizing Microbes from Marine Sediment on Cathodic Currents

    NASA Astrophysics Data System (ADS)

    Rowe, A. R.; Nealson, K. H.

    2013-12-01

    The ability of organisms to transfer electrons to and from substrates outside the cell is reshaping the way we look at microbial respiration. While this process, termed extracellular electron transport (EET), has been described in a number of metal reducing organisms, current evidence suggests that this process is widespread in nature and across physiologies. Additionally, it has been speculated that these previously overlooked electrochemical interactions may play an important role in global biogeochemical cycles. Requirements for EET could play a role in why the ';uncultured majority' have so far been resistant to culturing. As such, we are currently developing culturing techniques to target microbes capable of utilizing insoluble electron acceptors utilizing electrochemical techniques. Microbe-electrode interactions are analogous to the reactions that occur between microbes and minerals and may provide an apt way to mimic the environmental conditions (i.e., insoluble electron donor/acceptor at specific redox potentials) required for culturing specialized or EET dependent metabolisms. It has been previously demonstrated that aquatic sediments are capable of utilizing anodes as electron acceptors, thereby generating a current. While, it is known that microbes utilize electrons from a cathode for the reduction of different metals and oxygen in microbial fuel cells, currently there are no reports of environmental enrichments of microbes using cathodes. Replicate microcosms from marine sediments (sampled from Catalina Harbor, California) were incubated with ITO plated glass electrodes. Negative current production at -400mV (vs. Ag/AgCl reference electrodes) potentials was sustained for four weeks. Secondary enrichments were then constructed using the cathode as the primary electron source and a variety of anaerobic terminal electron acceptors--Nitrate, Fe3+, and SO42-. Positive current was maintained in enrichment cultures (compared to abiotic control containing

  8. Microbial fuel cells with highly active aerobic biocathodes

    NASA Astrophysics Data System (ADS)

    Milner, Edward M.; Popescu, Dorin; Curtis, Tom; Head, Ian M.; Scott, Keith; Yu, Eileen H.

    2016-08-01

    Microbial fuel cells (MFCs), which convert organic waste to electricity, could be used to make the wastewater infrastructure more energy efficient and sustainable. However, platinum and other non-platinum chemical catalysts used for the oxygen reduction reaction (ORR) at the cathode of MFCs are unsustainable due to their high cost and long-term degradation. Aerobic biocathodes, which use microorganisms as the biocatalysts for cathode ORR, are a good alternative to chemical catalysts. In the current work, high-performing aerobic biocathodes with an onset potential for the ORR of +0.4 V vs. Ag/AgCl were enriched from activated sludge in electrochemical half-cells poised at -0.1 and + 0.2 V vs. Ag/AgCl. Gammaproteobacteria, distantly related to any known cultivated gammaproteobacterial lineage, were identified as dominant in these working electrode biofilms (23.3-44.3% of reads in 16S rRNA gene Ion Torrent libraries), and were in very low abundance in non-polarised control working electrode biofilms (0.5-0.7%). These Gammaproteobacteria were therefore most likely responsible for the high activity of biologically catalysed ORR. In MFC tests, a high-performing aerobic biocathode increased peak power 9-fold from 7 to 62 μW cm-2 in comparison to an unmodified carbon cathode, which was similar to peak power with a platinum-doped cathode at 70 μW cm-2.

  9. Cadmium (II) removal mechanisms in microbial electrolysis cells.

    PubMed

    Colantonio, Natalie; Kim, Younggy

    2016-07-05

    Cadmium is a toxic heavy metal, causing serious environmental and human health problems. Conventional methods for removing cadmium from wastewater are expensive and inefficient for low concentrations. Microbial electrolysis cells (MECs) can simultaneously treat wastewater, produce hydrogen gas, and remove heavy metals with low energy requirements. Lab-scale MECs were operated to remove cadmium under various electric conditions: applied voltages of 0.4, 0.6, 0.8, and 1.0 V; and a fixed cathode potential of -1.0 V vs. Ag/AgCl. Regardless of the electric condition, rapid removal of cadmium was demonstrated (50-67% in 24 h); however, cadmium concentration in solution increased after the electric current dropped with depleted organic substrate under applied voltage conditions. For the fixed cathode potential, the electric current was maintained even after substrate depletion and thus cadmium concentration did not increase. These results can be explained by three different removal mechanisms: cathodic reduction; Cd(OH)2 precipitation; and CdCO3 precipitation. When the current decreased with depleted substrates, local pH at the cathode was no longer high due to slowed hydrogen evolution reaction (2H(+)+2e(-)→H2); thus, the precipitated Cd(OH)2 and CdCO3 started dissolving. To prevent their dissolution, sufficient organic substrates should be provided when MECs are used for cadmium removal. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Turning Waste Chemicals into Wealth—A New Approach To Synthesize Efficient Cathode Material for an Li–O 2 Battery

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yao, Ying; Wu, Feng

    An Li–O 2 battery requires the oxygen-breathing cathode to be highly electronically conductive, rapidly oxygen diffusive, structurally stable, and often times electrocatalytically active. Catalyst-decorated porous carbonaceous materials are the chosen air cathode in this regard. Alternatively, biomass-derived carbonaceous materials possess great ability to remove heavy and toxic metal ions from waste, forming a metal-adsorbed porous carbonaceous material. The similar structure between the air cathode and the metal-adsorbed biomass-derived carbon nicely bridges these two irrelevant areas. In this study, we investigated the electrochemical activity of a biochar material Ag-ESB directly synthesized from ethanol sludge residue in a rechargeable aprotic Li–O 2more » battery. Ag ions were adsorbed from sewage and became Ag nanoparticles with uniform coverage on the biochar surface. The as-prepared material exhibits good electrochemical behavior in battery testing, especially toward the battery efficiency and cyclability. This study provides the possibility of synthetically efficient cathode material by reusing “waste” such as biofuel sludge residue. It is an economically and environmentally friendly approach both for an energy-storage system and for waste recycling.« less

  11. Silver/iron oxide/graphitic carbon composites as bacteriostatic catalysts for enhancing oxygen reduction in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Ma, Ming; You, Shijie; Gong, Xiaobo; Dai, Ying; Zou, Jinlong; Fu, Honggang

    2015-06-01

    Biofilms from anode heterotrophic bacteria are inevitably formed over cathodic catalytic sites, limiting the performances of single-chamber microbial fuel cells (MFCs). Graphitic carbon (GC) - based nano silver/iron oxide (AgNPs/Fe3O4/GC) composites are prepared from waste pomelo skin and used as antibacterial oxygen reduction catalysts for MFCs. AgNPs and Fe3O4 are introduced in situ into the composites by one-step carbothermal reduction, enhancing their conductivity and catalytic activity. To investigate the effects of Fe species on the antibacterial and catalytic properties, AgNPs/Fe3O4/GC is washed with sulfuric acid (1 mol L-1) for 0.5 h, 1 h, and 5 h and marked as AgNPs/Fe3O4/GC-x (x = 0.5 h, 1 h and 5 h, respectively). A maximum power density of 1712 ± 35 mW m-2 is obtained by AgNPs/Fe3O4/GC-1 h, which declines by 4.12% after 17 cycles. Under catalysis of all AgNP-containing catalysts, oxygen reduction reaction (ORR) proceeds via the 4e- pathway, and no toxic effects to anode microorganisms result from inhibiting the cathodic biofilm overgrowth. With the exception of AgNPs/Fe3O4/GC-5 h, the AgNPs-containing composites exhibit remarkable power output and coulombic efficiency through lowering proton transfer resistance and air-cathode biofouling. This study provides a perspective for the practical application of MFCs using these efficient antibacterial ORR catalysts.

  12. Metal-air cells comprising collapsible foam members and means for minimizing internal pressure buildup

    NASA Technical Reports Server (NTRS)

    Putt, Ronald A. (Inventor); Woodruff, Glenn (Inventor)

    1994-01-01

    This invention provides a prismatic zinc-air cell including, in general, a prismatic container having therein an air cathode, a separator and a zinc anode. The container has one or more oxygen access openings, and the air cathode is disposed in the container in gaseous communication with the oxygen access openings so as to allow access of oxygen to the cathode. The separator has a first side in electrolytic communication with the air cathode and a second side in electrolytic communication with the zinc anode. The separator isolates the cathode and the zinc anode from direct electrical contact and allows passage of electrolyte therebetween. An expansion chamber adjacent to the zinc anode is provided which accommodates expansion of the zinc anode during discharge of the cell. A suitable collapsible foam member generally occupies the expansion space, providing sufficient resistance tending to oppose movement of the zinc anode away from the separator while collapsing upon expansion of the zinc anode during discharge of the cell. One or more vent openings disposed in the container are in gaseous communication with the expansion space, functioning to satisfactorily minimize the pressure buildup within the container by venting gasses expelled as the foam collapses during cell discharge.

  13. The Salty Science of the Aluminum-Air Battery

    NASA Astrophysics Data System (ADS)

    Chasteen, Stephanie V.; Chasteen, N. Dennis; Doherty, Paul

    2008-12-01

    Fruit batteries and saltwater batteries are excellent ways to explore simple circuits in the classroom. These are examples of air batteries in which metal reacts with oxygen in the air in order to generate free electrons, which flow through an external circuit and do work. Students are typically told that the salt or fruit water acts as an electrolyte to bring electrons from the anode to the cathode. That's true, but it leaves the battery as a black box. Physics teachers often don't have the background to explain the chemistry behind these batteries. We've written this paper to explore the electrochemistry behind an air battery using copper cathode, aluminum anode, and saltwater.

  14. Characterization of a microbial fuel cell with reticulated carbon foam electrodes.

    PubMed

    Lepage, Guillaume; Albernaz, Fabio Ovenhausen; Perrier, Gérard; Merlin, Gérard

    2012-11-01

    A microbial fuel cell with open-pore reticulated vitreous carbon electrodes is studied to assess the suitability of this material in a batch mode, in the perspective of flow-through reactors for wastewater treatment with electricity generation. The cell shows good stability and fair robustness in regards to substrate cycles. A power density of 40 W/m(3) is reached. The cell efficiency is mainly limited by cathodic transfers, representing 85% of the global overpotential in open circuit. Through impedance spectrocopy, equivalent circuit modeling reveals the complex nature of the bioelectrochemical phenomena. The global electrical behavior of the cell seems to result in the addition of three anodic and two cathodic distinct phenomena. On the cathode side, the Warburg element in the model is related to the diffusion of oxygen. Warburg resistance and time are respectively 2.99 kΩ cm(2) and 16.4s, similar to those published elsewhere. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhen Li; Rishika Haynes; Eugene Sato

    Microbial fuel cells (MFCs) convert chemical energy to electrical energy via bioelectrochemical reactions mediated by microorganisms. We investigated the diversity of the microbial community in an air cathode single chamber MFC that utilized potato-process wastewater as substrate. Terminal Restriction Fragment Length Polymorphism (T-RFLP) results indicated that the bacterial communities on the anode, cathode, control electrode, and MFC bulk fluid were similar, but differed dramatically from that of the anaerobic domestic sludge and potato wastewater inoculum. The 16S rDNA sequencing results showed that microbial species detected on the anode were predominantly within the phyla of Proteobacteria, Firmicutes, and Bacteroidetes. Fluorescent microscopymore » results indicated that there was a clear enhancement of biofilm formation on the anode. Results of this study could help improve understanding of the complexity of microbial communities and optimize the microbial composition for generating electricity by MFCs that utilize potato wastewater.« less

  16. Stacked microbial desalination cells to enhance water desalination efficiency.

    PubMed

    Chen, Xi; Xia, Xue; Liang, Peng; Cao, Xiaoxin; Sun, Haotian; Huang, Xia

    2011-03-15

    Microbial desalination cell (MDC) is a new method to obtain clean water from brackish water using electricity generated from organic matters by exoelectrogenic bacteria. Anions and cations, derived from salt solution filled in the desalination chamber between the anode and cathode, move to the anode and cathode chambers under the force of electrical field, respectively. On the basis of the primitive single-desalination-chambered MDC, stacked microbial desalination cells (SMDCs) were developed in order to promote the desalination rate in the present study. The effects of desalination chamber number and external resistance were investigated. Results showed that a remarkable increase in the total desalination rate (TDR) could be obtained by means of increasing the desalination cell number and reducing the external resistance, which caused the charge transfer efficiency increased since the SMDCs enabled more pairs of ions separated while one electron passed through the external circuit. The maximum TDR of 0.0252 g/h was obtained using a two-desalination-chambered SMDC with an external resistance of 10 Ω, which was 1.4 times that of single-desalination-chambered MDC. SMDCs proved to be an effective approach to increase the total water desalination rate if provided a proper desalination chamber number and external resistance.

  17. Effect of light on the production of bioelectricity and added-value microalgae biomass in a Photosynthetic Alga Microbial Fuel Cell.

    PubMed

    Gouveia, Luísa; Neves, Carole; Sebastião, Diogo; Nobre, Beatriz P; Matos, Cristina T

    2014-02-01

    This study demonstrates the simultaneous production of bioelectricity and added-value pigments in a Photosynthetic Alga Microbial Fuel Cell (PAMFC). A PAMFC was operated using Chlorella vulgaris in the cathode compartment and a bacterial consortium in the anode. The system was studied at two different light intensities and the maximum power produced was 62.7 mW/m(2) with a light intensity of 96 μE/(m(2)s). The results showed that increasing light intensity from 26 to 96 μE/(m(2)s) leads to an increase of about 6-folds in the power produced. Additionally, the pigments produced by the microalga were analysed and the results showed that the light intensity and PAMFC operation potentiated the carotenogenesis in the cathode compartment. The demonstrated possibility of producing added-value microalgae biomass in microbial fuel cell cathodes will increase the economic feasibility of these bioelectrochemical systems, allowing the development of energy efficient systems for wastewater treatment and carbon fixation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Two stage bioethanol refining with multi litre stacked microbial fuel cell and microbial electrolysis cell.

    PubMed

    Sugnaux, Marc; Happe, Manuel; Cachelin, Christian Pierre; Gloriod, Olivier; Huguenin, Gérald; Blatter, Maxime; Fischer, Fabian

    2016-12-01

    Ethanol, electricity, hydrogen and methane were produced in a two stage bioethanol refinery setup based on a 10L microbial fuel cell (MFC) and a 33L microbial electrolysis cell (MEC). The MFC was a triple stack for ethanol and electricity co-generation. The stack configuration produced more ethanol with faster glucose consumption the higher the stack potential. Under electrolytic conditions ethanol productivity outperformed standard conditions and reached 96.3% of the theoretically best case. At lower external loads currents and working potentials oscillated in a self-synchronized manner over all three MFC units in the stack. In the second refining stage, fermentation waste was converted into methane, using the scale up MEC stack. The bioelectric methanisation reached 91% efficiency at room temperature with an applied voltage of 1.5V using nickel cathodes. The two stage bioethanol refining process employing bioelectrochemical reactors produces more energy vectors than is possible with today's ethanol distilleries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Proton transfer in microbial electrolysis cells

    DOE PAGES

    Borole, Abhijeet P.; Lewis, Alex J.

    2017-02-15

    Proton transfer and electron transfer are of prime importance in the development of microbial electrochemical cells. While electron transfer is primarily controlled by biology, proton transfer is controlled by process engineering and cell design. To develop commercially feasible technologies around the concept of a bioelectrochemical cell, real feedstocks have to be explored and associated limitations have to be identified. Here in this study, the proton transfer rate was quantified for a microbial electrolysis cell (MEC) and its dependence on process parameters was investigated using a proton balance model. The reaction system consisted of a biomass-derived pyrolytic aqueous stream as amore » substrate producing hydrogen in a flow-through MEC. The proton transfer rate increased with anode flow rate and organic loading rate up to a maximum of 0.36 ± 0.01 moles per m 2 per h, equivalent to a hydrogen production rate of 9.08 L per L per day. Higher rates of hydrogen production, reaching 11.7 ± 0.2 L per L per day were achieved, when additional protons were provided via the cathode buffer. Electrochemical impedance spectroscopy shows that proton transfer was the dominant resistance in the production of hydrogen. The quantification of proton transfer rates for MECs with potential for biorefinery application and the demonstration of high hydrogen production rates approaching those required for commercial consideration indicate the strong potential of this technology for renewable hydrogen production. Understanding the transport phenomenon in bioelectrochemical cells is of great significance since these systems have potential for wide-ranging applications including energy production, bioremediation, chemical and nanomaterial synthesis, electro-fermentation, energy storage, desalination, and produced water treatment. Electron transfer in anode biofilms has been investigated extensively, but proton transfer studies are also important, since many cathodic half reactions

  20. Proton transfer in microbial electrolysis cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Borole, Abhijeet P.; Lewis, Alex J.

    Proton transfer and electron transfer are of prime importance in the development of microbial electrochemical cells. While electron transfer is primarily controlled by biology, proton transfer is controlled by process engineering and cell design. To develop commercially feasible technologies around the concept of a bioelectrochemical cell, real feedstocks have to be explored and associated limitations have to be identified. Here in this study, the proton transfer rate was quantified for a microbial electrolysis cell (MEC) and its dependence on process parameters was investigated using a proton balance model. The reaction system consisted of a biomass-derived pyrolytic aqueous stream as amore » substrate producing hydrogen in a flow-through MEC. The proton transfer rate increased with anode flow rate and organic loading rate up to a maximum of 0.36 ± 0.01 moles per m 2 per h, equivalent to a hydrogen production rate of 9.08 L per L per day. Higher rates of hydrogen production, reaching 11.7 ± 0.2 L per L per day were achieved, when additional protons were provided via the cathode buffer. Electrochemical impedance spectroscopy shows that proton transfer was the dominant resistance in the production of hydrogen. The quantification of proton transfer rates for MECs with potential for biorefinery application and the demonstration of high hydrogen production rates approaching those required for commercial consideration indicate the strong potential of this technology for renewable hydrogen production. Understanding the transport phenomenon in bioelectrochemical cells is of great significance since these systems have potential for wide-ranging applications including energy production, bioremediation, chemical and nanomaterial synthesis, electro-fermentation, energy storage, desalination, and produced water treatment. Electron transfer in anode biofilms has been investigated extensively, but proton transfer studies are also important, since many cathodic half reactions

  1. Cathodes for molten-salt batteries

    NASA Technical Reports Server (NTRS)

    Argade, Shyam D.

    1993-01-01

    Viewgraphs of the discussion on cathodes for molten-salt batteries are presented. For the cathode reactions in molten-salt cells, chlorine-based and sulfur-based cathodes reactants have relatively high exchange current densities. Sulfur-based cathodes, metal sulfides, and disulfides have been extensively investigated. Primary thermal batteries of the Li-alloy/FeS2 variety have been available for a number of years. Chlorine based rechargable cathodes were investigated for the pulse power application. A brief introduction is followed by the experimental aspects of research, and the results obtained. Performance projections to the battery system level are discussed and the presentation is summarized with conclusions.

  2. Improved energy output levels from small-scale Microbial Fuel Cells.

    PubMed

    Ieropoulos, I; Greenman, J; Melhuish, C

    2010-04-01

    This study reports on the findings from the investigation into small-scale (6.25 mL) MFCs, connected together as a network of multiple units. The MFCs contained unmodified (no catalyst) carbon fibre electrodes and for initial and later experiments, a standard ion-exchange membrane for the proton transfer from the anode to the cathode. The anode microbial culture was of the type commonly found in domestic wastewater fed with 5 mM acetate as the carbon-energy (C/E) source. The cultures were mature and acclimatised in the MFC environment for approximately 2 months before being re-inoculated in the experimental MFC units. The cathode was of the O(2) diffusion open-to-air type, but for the purposes of the polarization experiments, the cathodic electrodes were moistened with ferricyanide. The main aim of this study was to investigate the effects of connecting multiples of MFC units together as a method of scale up by using stacks and comparison of the effects of different PEM and MFC structural materials on the performance. Impedance matching (maximum-power-transfer) was achieved through calculation of total internal impedance. Three different PEM materials were compared in otherwise identical MFCs in sets of three. For individual isolated MFCs, Hyflon E87-03 was shown to produce twice, whilst E87-10 produced approximately 1.5 times the power output of the control (standard) PEM. However, when MFCs containing the E87-03 and E87-10 membranes were connected in a stack, the system suffered from severe instability and cell reversal. To study the effects of the various polymeric MFC structural materials, four small-scale units were manufactured from three different types of RP material; acrylo-butadiene-styrene coated (ABS), ABS coated (ABS-MEK) and polycarbonate (polyC). The stack of four (4) units prototyped out of polyC produced the highest power density values in polarisation experiments (80 mW/m(2)). 2009 Elsevier B.V. All rights reserved.

  3. Removal of organic carbon and nitrogen in a membraneless flow-through microbial electrolysis cell.

    PubMed

    Hussain, Abid; Lebrun, Frédérique Matteau; Tartakovsky, Boris

    2017-07-01

    This study evaluated performance of an upflow membraneless microbial electrolysis cell (MEC) with flow-through electrodes for wastewater treatment. First, methane production and COD removal were evaluated in continuous flow experiments carried out using synthetic and municipal wastewater. A 29-75% increase in methane production was observed under bioelectrochemical conditions as compared to an anaerobic control. Next, simultaneous removal of COD and nitrogen was studied under microaerobic conditions created by continuous air injection to the anodic compartment of the MEC. While the presence of oxygen decreased Coulombic efficiency due to aerobic degradation of COD, enhanced ammonium removal with near zero nitrite and nitrate effluent concentrations was observed. Evidence of direct ammonium oxidation at the anode as well as nitrite and nitrate reduction at the cathode was obtained by comparing performances of MECs operated under anaerobic and microaerobic conditions with the control reactor operated at zero applied voltage. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  4. Scenario for Hollow Cathode End-Of-Life

    NASA Technical Reports Server (NTRS)

    Sarver-Verhey, Timothy R.

    2000-01-01

    Recent successful hollow cathode life tests have demonstrated that lifetimes can meet the requirements of several space applications. However, there are no methods for assessing cathode lifetime short of demonstrating the requirement. Previous attempts to estimate or predict cathode lifetime were based on relatively simple chemical depletion models derived from the dispenser cathode community. To address this lack of predicative capability, a scenario for hollow cathode lifetime under steady-state operating conditions is proposed. This scenario has been derived primarily from the operating behavior and post-test condition of a hollow cathode that was operated for 28,000 hours. In this scenario, the insert chemistry evolves through three relatively distinct phases over the course of the cathode lifetime. These phases are believed to correspond to demonstrable changes in cathode operation. The implications for cathode lifetime limits resulting from this scenario are examined, including methods to assess cathode lifetime without operating to End-of- Life and methods to extend the cathode lifetime.

  5. Oxygen-selective immobilized liquid membranes for operation of lithium-air batteries in ambient air

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Xu, Wu; Liu, Wei

    In this work, nonaqueous electrolyte-based Li-air batteries with an O 2-selective membrane have been developed for operation in ambient air of 20-30% relative humidity (RH). The O 2 gas is continuously supplied through a membrane barrier layer at the interface of the cathode and ambient air. The membrane allows O 2 to permeate through while blocking moisture. Such membranes can be prepared by loading O 2-selective silicone oils into porous supports such as porous metal sheets and Teflon (PTFE) films. It was found that the silicone oil of high viscosity shows better performance. The immobilized silicone oil membrane in the porous PTFE film enabled the Li-air batteries with carbon black air electrodes to operate in ambient air (at 20% RH) for 16.3 days with a specific capacity of 789 mAh g -1 carbon and a specific energy of 2182 Wh kg -1 carbon. Its performance is much better than a reference battery assembled with a commercial, porous PTFE diffusion membranes as the moisture barrier layer on the cathode, which only had a discharge time of 5.5 days corresponding to a specific capacity of 267 mAh g -1 carbon and a specific energy of 704 Wh kg -1 carbon. The Li-air battery with the present selective membrane barrier layer even showed better performance in ambient air operation (20% RH) than the reference battery tested in the dry air box (<1% RH).

  6. AFM as an analysis tool for high-capacity sulfur cathodes for Li–S batteries

    PubMed Central

    Sörgel, Seniz; Costa, Rémi; Carlé, Linus; Galm, Ines; Cañas, Natalia; Pascucci, Brigitta; Friedrich, K Andreas

    2013-01-01

    Summary In this work, material-sensitive atomic force microscopy (AFM) techniques were used to analyse the cathodes of lithium–sulfur batteries. A comparison of their nanoscale electrical, electrochemical, and morphological properties was performed with samples prepared by either suspension-spraying or doctor-blade coating with different binders. Morphological studies of the cathodes before and after the electrochemical tests were performed by using AFM and scanning electron microscopy (SEM). The cathodes that contained polyvinylidene fluoride (PVDF) and were prepared by spray-coating exhibited a superior stability of the morphology and the electric network associated with the capacity and cycling stability of these batteries. A reduction of the conductive area determined by conductive AFM was found to correlate to the battery capacity loss for all cathodes. X-ray diffraction (XRD) measurements of Li2S exposed to ambient air showed that insulating Li2S hydrolyses to insulating LiOH. This validates the significance of electrical ex-situ AFM analysis after cycling. Conductive tapping mode AFM indicated the existence of large carbon-coated sulfur particles. Based on the analytical findings, the first results of an optimized cathode showed a much improved discharge capacity of 800 mA·g(sulfur)−1 after 43 cycles. PMID:24205455

  7. Characterization of microbial contamination in United States Air Force aviation fuel tanks.

    PubMed

    Rauch, Michelle E; Graef, Harold W; Rozenzhak, Sophie M; Jones, Sharon E; Bleckmann, Charles A; Kruger, Randell L; Naik, Rajesh R; Stone, Morley O

    2006-01-01

    Bacteria and fungi, isolated from United States Air Force (USAF) aviation fuel samples, were identified by gas chromatograph fatty acid methyl ester (GC-FAME) profiling and 16S or 18S rRNA gene sequencing. Thirty-six samples from 11 geographically separated USAF bases were collected. At each base, an above-ground storage tank, a refueling truck, and an aircraft wing tank were sampled at the lowest sample point, or sump, to investigate microbial diversity and dispersion within the fuel distribution chain. Twelve genera, including four Bacillus species and two Staphylococcus species, were isolated and identified. Bacillus licheniformis, the most prevalent organism isolated, was found at seven of the 11 bases. Of the organisms identified, Bacillus sp., Micrococcus luteus, Sphinogmonas sp., Staphylococcus sp., and the fungus Aureobasidium pullulans have previously been isolated from aviation fuel samples. The bacteria Pantoea ananatis, Arthrobacter sp., Alcaligenes sp., Kocuria rhizophilia, Leucobacter komagatae, Dietza sp., and the fungus Discophaerina fagi have not been previously reported in USAF aviation fuel. Only at two bases were the same organisms isolated from all three sample points in the fuel supply distribution chain. Isolation of previously undocumented organisms suggests either, changes in aviation fuel microbial community in response to changes in aviation fuel composition, additives and biocide use, or simply, improvements in isolation and identification techniques.

  8. Temporal variation in airborne microbial populations and microbially-derived allergens in a tropical urban landscape

    NASA Astrophysics Data System (ADS)

    Woo, Anthony C.; Brar, Manreetpal S.; Chan, Yuki; Lau, Maggie C. Y.; Leung, Frederick C. C.; Scott, James A.; Vrijmoed, Lilian L. P.; Zawar-Reza, Peyman; Pointing, Stephen B.

    2013-08-01

    The microbial component of outdoor aerosols was assessed along a gradient of urban development from inner-city to rural in the seasonal-tropical metropolis of Hong Kong. Sampling over a continuous one-year period was conducted, with molecular analyses to characterize bacterial and eukaryal microbial populations, immuno-assays to detect microbially-derived allergens and extensive environmental and meteorological observations. The data revealed bio-aerosol populations were not significantly impacted by the level of urban development as measured by anthropogenic pollutants and human population levels, but instead exhibited a strong seasonal trend related to general climatic variables. We applied back-trajectory analysis to establish sources of air masses and this allowed further explanation of urban bio-aerosols largely in terms of summer-marine and winter-continental origins. We also evaluated bio-aerosols for the potential to detect human health threats. Many samples supported bacterial and fungal phylotypes indicative of known pathogenic taxa, together with common indicators of human presence. The occurrence of allergenic endotoxins and beta-glucans generally tracked trends in microbial populations, with levels known to induce symptoms detected during summer months when microbial loading was higher. This strengthens calls for bio-aerosols to be considered in future risk assessments and surveillance of air quality, along with existing chemical and particulate indices.

  9. Outlook for benefits of sediment microbial fuel cells with two bio‐electrodes

    PubMed Central

    De Schamphelaire, Liesje; Rabaey, Korneel; Boeckx, Pascal; Boon, Nico; Verstraete, Willy

    2008-01-01

    Summary The benefits of sediment microbial fuel cells (SMFCs) go beyond energy generation for low‐power applications. Aside from producing electrical energy, SMFCs can enhance the oxidation of reduced compounds at the anode, thus bringing about the removal of excessive or unwanted reducing equivalents from submerged soils. Moreover, an SMFC could be applied to control redox‐dependent processes in sediment layers. Several cathodic reactions that may drive these sediment oxidation reactions are examined. Special attention is given to two biologically mediated cathodic reactions, respectively employing an oxygen reduction and a manganese cycle. Both reactions imply a low cost and a high electrode potential and are of interest for reactor‐type MFCs as well as for SMFCs. PMID:21261866

  10. Voltage instability in a simulated fuel cell stack correlated to cathode water accumulation

    NASA Astrophysics Data System (ADS)

    Owejan, J. P.; Trabold, T. A.; Gagliardo, J. J.; Jacobson, D. L.; Carter, R. N.; Hussey, D. S.; Arif, M.

    Single fuel cells running independently are often used for fundamental studies of water transport. It is also necessary to assess the dynamic behavior of fuel cell stacks comprised of multiple cells arranged in series, thus providing many paths for flow of reactant hydrogen on the anode and air (or pure oxygen) on the cathode. In the current work, the flow behavior of a fuel cell stack is simulated by using a single-cell test fixture coupled with a bypass flow loop for the cathode flow. This bypass simulates the presence of additional cells in a stack and provides an alternate path for airflow, thus avoiding forced convective purging of cathode flow channels. Liquid water accumulation in the cathode is shown to occur in two modes; initially nearly all the product water is retained in the gas diffusion layer until a critical saturation fraction is reached and then water accumulation in the flow channels begins. Flow redistribution and fuel cell performance loss result from channel slug formation. The application of in-situ neutron radiography affords a transient correlation of performance loss to liquid water accumulation. The current results identify a mechanism whereby depleted cathode flow on a single cell leads to performance loss, which can ultimately cause an operating proton exchange membrane fuel cell stack to fail.

  11. Non-microbial sources of microbial volatile organic compounds.

    PubMed

    Choi, Hyunok; Schmidbauer, Norbert; Bornehag, Carl-Gustaf

    2016-07-01

    The question regarding the true sources of the purported microbial volatile organic compounds (MVOCs) remains unanswered. To identify microbial, as well as non-microbial sources of 28 compounds, which are commonly accepted as microbial VOCs (i.e. primary outcome of interest is Σ 28 VOCs). In a cross-sectional investigation of 390 homes, six building inspectors assessed water/mold damage, took air and dust samples, and measured environmental conditions (i.e., absolute humidity (AH, g/m(3)), temperature (°C), ventilation rate (ACH)). The air sample was analyzed for volatile organic compounds (μg/m(3)) and; dust samples were analyzed for total viable fungal concentration (CFU/g) and six phthalates (mg/g dust). Four benchmark variables of the underlying sources were defined as highest quartile categories of: 1) the total concentration of 17 propylene glycol and propylene glycol ethers (Σ17 PGEs) in the air sample; 2) 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TMPD-MIB) in the air sample; 3) semi-quantitative mold index; and 4) total fungal load (CFU/g). Within severely damp homes, co-occurrence of the highest quartile concentration of either Σ17 PGEs or TMPD-MIB were respectively associated with a significantly higher median concentration of Σ 28 VOCs (8.05 and 13.38μg/m(3), respectively) compared to the reference homes (4.30 and 4.86μg/m(3), respectively, both Ps ≤0.002). Furthermore, the homes within the highest quartile range for Σ fungal load as well as AH were associated with a significantly increased median Σ 28 VOCs compared to the reference group (8.74 vs. 4.32μg/m(3), P=0.001). Within the final model of multiple indoor sources on Σ 28 VOCs, one natural log-unit increase in summed concentration of Σ17 PGEs, plus TMPD-MIB (Σ 17 PGEs + TMPD-MIB) was associated with 1.8-times (95% CI, 1.3-2.5), greater likelihood of having a highest quartile of Σ 28 VOCs, after adjusting for absolute humidity, history of repainting at least one room

  12. Phylogenetic and Metagenomic Analyses of Substrate-Dependent Bacterial Temporal Dynamics in Microbial Fuel Cells

    PubMed Central

    Zhang, Husen; Chen, Xi; Braithwaite, Daniel; He, Zhen

    2014-01-01

    Understanding the microbial community structure and genetic potential of anode biofilms is key to improve extracellular electron transfers in microbial fuel cells. We investigated effect of substrate and temporal dynamics of anodic biofilm communities using phylogenetic and metagenomic approaches in parallel with electrochemical characterizations. The startup non-steady state anodic bacterial structures were compared for a simple substrate, acetate, and for a complex substrate, landfill leachate, using a single-chamber air-cathode microbial fuel cell. Principal coordinate analysis showed that distinct community structures were formed with each substrate type. The bacterial diversity measured as Shannon index decreased with time in acetate cycles, and was restored with the introduction of leachate. The change of diversity was accompanied by an opposite trend in the relative abundance of Geobacter-affiliated phylotypes, which were acclimated to over 40% of total Bacteria at the end of acetate-fed conditions then declined in the leachate cycles. The transition from acetate to leachate caused a decrease in output power density from 243±13 mW/m2 to 140±11 mW/m2, accompanied by a decrease in Coulombic electron recovery from 18±3% to 9±3%. The leachate cycles selected protein-degrading phylotypes within phylum Synergistetes. Metagenomic shotgun sequencing showed that leachate-fed communities had higher cell motility genes including bacterial chemotaxis and flagellar assembly, and increased gene abundance related to metal resistance, antibiotic resistance, and quorum sensing. These differentially represented genes suggested an altered anodic biofilm community in response to additional substrates and stress from the complex landfill leachate. PMID:25202990

  13. Phylogenetic and metagenomic analyses of substrate-dependent bacterial temporal dynamics in microbial fuel cells.

    PubMed

    Zhang, Husen; Chen, Xi; Braithwaite, Daniel; He, Zhen

    2014-01-01

    Understanding the microbial community structure and genetic potential of anode biofilms is key to improve extracellular electron transfers in microbial fuel cells. We investigated effect of substrate and temporal dynamics of anodic biofilm communities using phylogenetic and metagenomic approaches in parallel with electrochemical characterizations. The startup non-steady state anodic bacterial structures were compared for a simple substrate, acetate, and for a complex substrate, landfill leachate, using a single-chamber air-cathode microbial fuel cell. Principal coordinate analysis showed that distinct community structures were formed with each substrate type. The bacterial diversity measured as Shannon index decreased with time in acetate cycles, and was restored with the introduction of leachate. The change of diversity was accompanied by an opposite trend in the relative abundance of Geobacter-affiliated phylotypes, which were acclimated to over 40% of total Bacteria at the end of acetate-fed conditions then declined in the leachate cycles. The transition from acetate to leachate caused a decrease in output power density from 243±13 mW/m2 to 140±11 mW/m2, accompanied by a decrease in Coulombic electron recovery from 18±3% to 9±3%. The leachate cycles selected protein-degrading phylotypes within phylum Synergistetes. Metagenomic shotgun sequencing showed that leachate-fed communities had higher cell motility genes including bacterial chemotaxis and flagellar assembly, and increased gene abundance related to metal resistance, antibiotic resistance, and quorum sensing. These differentially represented genes suggested an altered anodic biofilm community in response to additional substrates and stress from the complex landfill leachate.

  14. Fermentation and microbial population dynamics during the ensiling of native grass and subsequent exposure to air.

    PubMed

    Zhang, Qing; Wu, Baiyila; Nishino, Naoki; Wang, Xianguo; Yu, Zhu

    2016-03-01

    To study the microbial population and fermentation dynamics of large needlegrass (LN) and Chinese leymus (CL) during ensiling and subsequent exposure to air, silages were sampled and analyzed using culture-based techniques and denaturing gradient gel electrophoresis (DGGE). A total of 112 lactic acid bacteria (LAB) strains were isolated and identified using the 16S rRNA sequencing method. Lactic acid was not detected in the first 20 days in LN silage and the pH decreased to 6.13 after 45 days of ensiling. The temperature of the LN silage increased after approximately 30 h of air exposure and the CL silage showed a slight temperature variation. Enterococcus spp. were mainly present in LN silage. The proportion of Lactobacillus brevis in CL silage increased after exposure to air. LN silage with a higher proportion of Enterococcus spp. and propionic acid concentration did not show higher fermentation quality or aerobic stability than CL silage, which had a higher concentration of acetic acid, butyric acid and increased proportion of L. brevis after exposure to air. © 2015 Japanese Society of Animal Science.

  15. Humans differ in their personal microbial cloud

    PubMed Central

    Altrichter, Adam E.; Bateman, Ashley C.; Stenson, Jason; Brown, GZ; Green, Jessica L.; Bohannan, Brendan J.M.

    2015-01-01

    Dispersal of microbes between humans and the built environment can occur through direct contact with surfaces or through airborne release; the latter mechanism remains poorly understood. Humans emit upwards of 106 biological particles per hour, and have long been known to transmit pathogens to other individuals and to indoor surfaces. However it has not previously been demonstrated that humans emit a detectible microbial cloud into surrounding indoor air, nor whether such clouds are sufficiently differentiated to allow the identification of individual occupants. We used high-throughput sequencing of 16S rRNA genes to characterize the airborne bacterial contribution of a single person sitting in a sanitized custom experimental climate chamber. We compared that to air sampled in an adjacent, identical, unoccupied chamber, as well as to supply and exhaust air sources. Additionally, we assessed microbial communities in settled particles surrounding each occupant, to investigate the potential long-term fate of airborne microbial emissions. Most occupants could be clearly detected by their airborne bacterial emissions, as well as their contribution to settled particles, within 1.5–4 h. Bacterial clouds from the occupants were statistically distinct, allowing the identification of some individual occupants. Our results confirm that an occupied space is microbially distinct from an unoccupied one, and demonstrate for the first time that individuals release their own personalized microbial cloud. PMID:26417541

  16. Erosion behavior of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Franz, Robert, E-mail: robert.franz@unileoben.ac.at; Mendez Martin, Francisca; Hawranek, Gerhard

    2016-03-15

    Al{sub x}Cr{sub 1−x} composite cathodes with Al contents of x = 0.75, 0.5, and 0.25 were exposed to cathodic arc plasmas in Ar, N{sub 2}, and O{sub 2} atmospheres and their erosion behavior was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by x-ray diffraction analysis. Cathode poisoning effects in the reactive N{sub 2} and O{sub 2} atmospheres were nonuniform as a resultmore » of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded center region of the cathodes.« less

  17. Effect of breathing-hole size on the electrochemical species in a free-breathing cathode of a DMFC

    NASA Astrophysics Data System (ADS)

    Hwang, J. J.; Wu, S. D.; Lai, L. K.; Chen, C. K.; Lai, D. Y.

    A three-dimensional numerical model is developed to study the electrochemical species characteristics in a free-breathing cathode of a direct methanol fuel cell (DMFC). A perforated current collector is attached to the porous cathode that breathes the fresh air through an array of orifices. The radius of the orifice is varied to examine its effect on the electrochemical performance. Gas flow in the porous cathode is governed by the Darcy equation with constant porosity and permeability. The multi-species diffusive transports in the porous cathode are described using the Stefan-Maxwell equation. Electrochemical reaction on the surfaces of the porous matrices is depicted via the Butler-Volmer equation. The charge transports in the porous matrices are dealt with by Ohm's law. The coupled equations are solved by a finite-element-based CFD technique. Detailed distributions of electrochemical species characteristics such as flow velocities, species mass fractions, species fluxes, and current densities are presented. The optimal breathing-hole radius is derived from the current drawn out of the porous cathode under a fixed overpotential.

  18. [Application of microbial fuel cell (MFC) in solid waste composting].

    PubMed

    Cui, Jinxin; Wang, Xin; Tang, Jingchun

    2012-03-01

    Microbial fuel cell (MFC) is a new technology that can recover energy from biomass with simultaneous waste treatment. This technique has been developed fast in recent years in combining with environmental techniques such as wastewater treatment, degradation of toxic pollutants and desalination. With the increase of solid waste, applying MFC in composting is promising due to its property of waste disposal with simultaneous energy generation. In this paper, the microbial community of MFCs during composting was summarized. Four major influencing factors including electrodes, separators, oxygen supplement and configurations on the performance of composting MFCs were discussed. The characteristics of composting MFC as a new technique for reducing solid waste were as follows: high microbial biomass resulted in the high current density; adaptable to different environmental conditions; self-adjustable temperature with high energy efficiency; the transportation of proton from anode to cathode were limited by different solid substrates.

  19. Operating theatre ventilation systems and microbial air contamination in total joint replacement surgery: results of the GISIO-ISChIA study.

    PubMed

    Agodi, A; Auxilia, F; Barchitta, M; Cristina, M L; D'Alessandro, D; Mura, I; Nobile, M; Pasquarella, C

    2015-07-01

    Recent studies have shown a higher rate of surgical site infections in hip prosthesis implantation using unidirectional airflow ventilation compared with turbulent ventilation. However, these studies did not measure the air microbial quality of operating theatres (OTs), and assumed it to be compliant with the recommended standards for this ventilation technique. To evaluate airborne microbial contamination in OTs during hip and knee replacement surgery, and compare the findings with values recommended for joint replacement surgery. Air samplings were performed in 28 OTs supplied with unidirectional, turbulent and mixed airflow ventilation. Samples were collected using passive sampling to determine the index of microbial air contamination (IMA). Active sampling was also performed in some of the OTs. The average number of people in the OT and the number of door openings during the sampling period were recorded. In total, 1228 elective prosthesis procedures (60.1% hip and 39.9% knee) were included in this study. Of passive samplings performed during surgical activity in unidirectional airflow ventilation OTs (U-OTs) and mixed airflow OTs (M-OTs), 58.9% and 87.6% had IMA values >2, respectively. Of samplings performed during surgical activity in turbulent airflow OTs (T-OTs) and in turbulent airflow OTs with the surgical team wearing Steri-Shield Turbo Helmets (TH-OTs), 8.6% and 60% had IMA values ≤ 2, respectively. Positive correlation was found between IMA values and the number of people in the OT and the number of door openings (P < 0.001). In addition, correlation was found between active and passive sampling (P < 0.001). These findings challenge the belief that unidirectional systems always provide acceptable airborne bacterial counts. Copyright © 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  20. Improved materials and processes of dispenser cathodes

    NASA Astrophysics Data System (ADS)

    Longo, R. T.; Sundquist, W. F.; Adler, E. A.

    1984-08-01

    Several process variables affecting the final electron emission properties of impregnated dispenser cathodes were investigated. In particular, the influence of billet porosity, impregnant composition and purity, and osmium-ruthenium coating were studied. Work function and cathode evaporation data were used to evaluate cathode performance and to formulate a model of cathode activation and emission. Results showed that sorted tungsten powder can be reproducibly fabricated into cathode billets. Billet porosity was observed to have the least effect on cathode performance. Use of the 4:1:1 aluminate mixture resulted in lower work functions than did use of the 5:3:2 mixture. Under similar drawout conditions, the coated cathodes showed superior emission relative to uncoated cathodes. In actual Pierce gun structures under accelerated life test, the influence of impregnated sulfur is clearly shown to reduce cathode performance.

  1. Cathode for aluminum producing electrolytic cell

    DOEpatents

    Brown, Craig W.

    2004-04-13

    A method of producing aluminum in an electrolytic cell comprising the steps of providing an anode in a cell, preferably a non-reactive anode, and also providing a cathode in the cell, the cathode comprised of a base material having low electrical conductivity reactive with molten aluminum to provide a highly electrically conductive layer on the base material. Electric current is passed from the anode to the cathode and alumina is reduced and aluminum is deposited at the cathode. The cathode base material is selected from boron carbide, and zirconium oxide.

  2. Durable rechargeable zinc-air batteries with neutral electrolyte and manganese oxide catalyst

    NASA Astrophysics Data System (ADS)

    Sumboja, Afriyanti; Ge, Xiaoming; Zheng, Guangyuan; Goh, F. W. Thomas; Hor, T. S. Andy; Zong, Yun; Liu, Zhaolin

    2016-11-01

    Neutral chloride-based electrolyte and directly grown manganese oxide on carbon paper are used as the electrolyte and air cathode respectively for rechargeable Zn-air batteries. Oxygen reduction and oxygen evolution reactions on manganese oxide show dependence of activities on the pH of the electrolyte. Zn-air batteries with chloride-based electrolyte and manganese oxide catalyst exhibit satisfactory voltage profile (discharge and charge voltage of 1 and 2 V at 1 mA cm-2) and excellent cycling stability (≈90 days of continuous cycle test), which is attributed to the reduced carbon corrosion on the air cathode and decreased carbonation in neutral electrolyte. This work describes a robust electrolyte system that improves the cycle life of rechargeable Zn-air batteries.

  3. Fundamental Impact of Humidity on SOFC Cathode ORR

    DOE PAGES

    Huang, Y. L.; Pellegrinelli, C.; Wachsman, E. D.

    2015-12-17

    Although solid oxide fuel cells (SOFC) have demonstrated excellent performance, the durability of SOFCs under real working conditions is still an issue for commercial deployment. In particular cathode exposure to atmospheric air contaminants, such as humidity, can result in long-term performance degradation issues. Therefore, a fundamental understanding of the interaction between water molecules and cathodes is essential to resolve this issue and further enhance cathode durability. In order to study the effects of humidity on the oxygen reduction reaction (ORR), we used in-situ 18O isotope exchange techniques to probe the exchange of water with two of themost common SOFC cathodemore » materials, (La 0.8Sr 0.2) 0.95MnO 3±δ (LSM) and La 0.6Sr 0.4Co 0.2Fe 0.8O 3-δ (LSCF). In this experiment, heavy water, D 2O (with a mass/charge ratio of m/z = 20), is used to avoid the overlapping of H 2O and the 18O 2 cracking fraction, which both provide a peak at m/z = 18. A series of temperature programmed isotope exchange measurements were performed to comprehensively study the interaction of water with the cathode surface as a function of temperature, oxygen partial pressure, and water vapor concentration. The results suggest that water and O 2 share the same surface exchange sites, leading to competitive adsorption. Our findings show that water prefers to exchange with LSCF at lower temperatures, around 300–450°C. For LSM, O 2 is more favorable than water to be adsorbed on the surface and the presence of O 2 limits water exchange. The experimental data are summarized in a Temperature-PO 2 diagram to help visualize how the exchange of water on each material depends on the operating conditions.« less

  4. Microbial safety in space

    NASA Astrophysics Data System (ADS)

    Krooneman, Janneke; Harmsen, Hermie; Landini, Paolo; Zinn, Manfred; Munaut, Françoise; van der Meer, Walter; Beimfohr, Claudia; Reichert, Bas; Preuß, Andrea

    2005-10-01

    Microbial hygiene is important in our daily lives; preventing and combating microbial infections is increasingly important in society. In hospitals, strict monitoring and control is exercised for people and infrastructure alike. In modern buildings, air-conditioning system are screened for harmful bacteria such as Legionella. More recently, concerns about SARS (virus) and anthrax (bacteria) have added pressure on the scientific community to come up with adequate monitoring and control techniques to assure microbial hygiene. Additionally, the use of biotechnological recycling and cleaning processes for sustainability brings the need for reliable monitoring tools and preventive or riks-reducing strategies. In the manned space environment, similar problems need to be solved and efforts have already been made to study the behaviour of micro-organisms and microbial hygiene onboard space stations.

  5. Influence of Pr6O11 on oxygen electroreduction kinetics and electrochemical performance of Sr2Fe1.5Mo0.5O6-δ based cathode

    NASA Astrophysics Data System (ADS)

    Osinkin, D. A.; Beresnev, S. M.; Bogdanovich, N. M.

    2018-07-01

    Oxygen electroreduction kinetics and electrochemical performance of the Pr6O11-impregnated Sr2Fe1.5Mo0.5O6-δ - Ce0.8Sm0.2O1.9 (SFM-SDC) cathode have been first studied. By means of distribution of relaxation times and non-linear least squares analysis of impedance spectra were shown that the addition of Pr6O11 into the cathode leads to the increase in the rate of the low-frequency step. It is suggested that the observed phenomenon is associated with the increase in the rate of surface oxygen exchange. It is shown that the introduction of praseodymium oxide into the cathode results in a decrease in the area specific polarization resistances of the cathode at equilibrium potentials from 0.23 to 0.06 Ω cm2 at 800 °C in air. The maximum power density of symmetrical solid oxide fuel cell (SOFC) with impregnated SFM-SDC electrodes and supporting 760 μm La0.85Sr0.15Ga0.85Mg0.15O3-δ electrolyte without buffer/barrier and collector layers under air/wet hydrogen (dry CH4) condition was about 0.5 (0.26) W cm-2 at 800 °C. The overvoltage of the cathode was higher than that of the anode under air/wet hydrogen and vice versa when methane was supplied to the anode. The obtained results elucidate that the impregnated SFM-SDC is a promising cathode for SOFC application.

  6. Concurrent Phosphorus Recovery and Energy Generation in Mediator-Less Dual Chamber Microbial Fuel Cells: Mechanisms and Influencing Factors

    PubMed Central

    Almatouq, Abdullah; Babatunde, Akintunde O.

    2016-01-01

    This study investigated the mechanism and key factors influencing concurrent phosphorus (P) recovery and energy generation in microbial fuel cells (MFC) during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite when ammonium and magnesium chloride solutions were added to the cathode chamber. Monitoring data for chemical oxygen demand (COD), pH, oxidation reduction potential (ORP) and aeration flow rate showed that a maximum 38% P recovery was achieved; and this corresponds to 1.5 g/L, pH > 8, −550 ± 10 mV and 50 mL/min respectively, for COD, pHcathode, ORP and cathode aeration flow rate. More importantly, COD and aeration flow rate were shown to be the key influencing factors for the P recovery and energy generation. Results further show that the maximum P recovery corresponds to 72 mW/m2 power density. However, the energy generated at maximum P recovery was not the optimum; this shows that whilst P recovery and energy generation can be concurrently achieved in a microbial fuel cell, neither can be at the optimal value. PMID:27043584

  7. Application of manures to mitigate the harmful effects of electrokinetic remediation of heavy metals on soil microbial properties in polluted soils.

    PubMed

    Tahmasbian, Iman; Safari Sinegani, Ali Akbar; Nguyen, Thi Thu Nhan; Che, Rongxiao; Phan, Thuc D; Hosseini Bai, Shahla

    2017-12-01

    Ethylenediaminetetraacetic acid (EDTA) used with electrokinetic (EK) to remediate heavy metal-polluted soils is a toxic chelate for soil microorganisms. Therefore, this study aimed to evaluate the effects of alternative organic chelates to EDTA on improving the microbial properties of a heavy metal-polluted soil subjected to EK. Cow manure extract (CME), poultry manure extract (PME) and EDTA were applied to a lead (Pb) and zinc (Zn)-polluted calcareous soil which were subjected to two electric intensities (1.1 and 3.3 v/cm). Soil carbon pools, microbial activity, microbial abundance (e.g., fungal, actinomycetes and bacterial abundances) and diethylenetriaminepentaacetic acid (DTPA)-extractable Pb and Zn (available forms) were assessed in both cathodic and anodic soils. Applying the EK to soil decreased all the microbial variables in the cathodic and anodic soils in the absence or presence of chelates. Both CME and PME applied with two electric intensities decreased the negative effect of EK on soil microbial variables. The lowest values of soil microbial variables were observed when EK was combined with EDTA. The following order was observed in values of soil microbial variables after treating with EK and chelates: EK + CME or EK + PME > EK > EK + EDTA. The CME and PME could increase the concentrations of available Pb and Zn, although the increase was less than that of EDTA. Overall, despite increasing soil available Pb and Zn, the combination of EK with manures (CME or PME) mitigated the negative effects of using EK on soil microbial properties. This study suggested that the synthetic chelates such as EDTA could be replaced with manures to alleviate the environmental risks of EK application.

  8. Nitrogen-doped graphene/CoNi alloy encased within bamboo-like carbon nanotube hybrids as cathode catalysts in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Hou, Yang; Yuan, Heyang; Wen, Zhenhai; Cui, Shumao; Guo, Xiaoru; He, Zhen; Chen, Junhong

    2016-03-01

    Cost-effective catalysts are of key importance to the successful deployment of microbial fuel cells (MFCs) for electricity generation from organic wastes. Herein, a novel catalyst prepared by one-step synthesis strategy is reported. The catalyst features N-doped bamboo-like carbon nanotube (BCNT) in which CoNi-alloy is encapsulated at the end and/or the middle section of the tube with many graphene layers inside inner cavities of BCNT (N-G@CoNi/BCNT). The prepared N-G@CoNi/BCNT exhibits a high oxygen reduction reaction (ORR) activity with an early onset potential of 0.06 V vs. Ag/AgCl and a comparable exchange current density to that of commercial Pt/C. The excellent catalytic activity is further evidenced by a high electron transfer number of 3.63. When being applied in MFCs, the N-G@CoNi/BCNT yields an average current density of 6.7 A m-2, slightly lower than that of Pt/C but with a less mass transfer potential loss. The cost of the N-G@CoNi/BCNT for constructing a 1-m2 cathode electrode is 200 times lower than that of Pt/C. With such a competitive price and excellent electrocatalytic-activity resulting from its unique morphology, CoNi-alloy/nitrogen dopants, considerable specific surface area, and carbon-coated alloy/graphene hybridization, the present catalyst is a promising candidate for ORR catalysts in MFCs for energy recovery from wastes.

  9. A survey of Kaufman thruster cathodes

    NASA Technical Reports Server (NTRS)

    Weigand, A. J.; Nakanishi, S.

    1971-01-01

    A survey is presented of the various cathodes which were developed and used in the Kaufman ion thruster. The electron bombardment type ion source is briefly described. The general design, operating characteristics, and power requirements are shown for each type of cathode from the refractory metals used in 1960 to the plasma discharge hollow cathodes of today. A detailed discussion of the hollow cathode is given, including starting and cyclic operating characteristics as well as more fundamental design parameters. Tests to date show that the plasma hollow cathode is an efficient electron source with demonstrated durability over 10,000 hours.

  10. Microbial fuel cell driving electrokinetic remediation of toxic metal contaminated soils.

    PubMed

    Habibul, Nuzahat; Hu, Yi; Sheng, Guo-Ping

    2016-11-15

    An investigation of the feasibility of in-situ electrokinetic remediation for toxic metal contaminated soil driven by microbial fuel cell (MFC) is presented. Results revealed that the weak electricity generated from MFC could power the electrokinetic remediation effectively. The metal removal efficiency and its influence on soil physiological properties were also investigated. With the electricity generated through the oxidation of organics in soils by microorganisms, the metals in the soils would mitigate from the anode to the cathode. The concentrations of Cd and Pb in the soils increased gradually through the anode to the cathode regions after remediation. After about 143days and 108 days' operation, the removal efficiencies of 31.0% and 44.1% for Cd and Pb at the anode region could be achieved, respectively. Soil properties such as pH and soil conductivity were also significantly redistributed from the anode to the cathode regions. The study shows that the MFC driving electrokinetic remediation technology is cost-effective and environmental friendly, with a promising application in soil remediation. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Miniature Reservoir Cathode: An Update

    NASA Technical Reports Server (NTRS)

    Vancil, Bernard K.; Wintucky, Edwin G.

    2002-01-01

    We report on recent work to produce a small low power, low cost reservoir cathode capable of long life (more than 100,000 hours) at high loading (> 5 A/sq cm). Our objective is a highly manufacturable, commercial device costing less than $30. Small highly loaded cathodes are needed, especially for millimeter wave tubes, where focusing becomes difficult when area convergence ratios are too high. We currently have 3 models ranging from .060-inch diameter to. 125-inch diameter. Reservoir type barium dispenser cathodes have a demonstrated capability for simultaneous high emission density and long life. Seven reservoir cathodes continue to operate on the cathode life test facility at NSWC, Crane, Indiana at 2 and 4 amps/sq cm. They have accumulated nearly 100,000 hours with practically no change in emission levels or knee temperature.

  12. Increasing phosphorus recovery from dewatering centrate in microbial electrolysis cells.

    PubMed

    Yuan, Pengyi; Kim, Younggy

    2017-01-01

    Microbial electrolysis cells (MECs) use bioelectrochemical reactions to remove organic contaminants at the bioanode and produce hydrogen gas at the cathode. High local pH conditions near the cathode can also be utilized to produce struvite from nutrient-rich wastewater. This beneficial aspect was investigated using lab-scale MECs fed with dewatering centrate collected at a local wastewater treatment plant. The main objective was to improve phosphorus recovery by examining various cathode configurations and electric current conditions. The stainless steel mesh (SSM) cathode was relatively inefficient to achieve complete phosphorus recovery because struvite crystals were smaller (a few to tens of micrometers) than the open space between mesh wires (80 µm). As a result, the use of multiple pieces of SSM also showed a limited improvement in the phosphorus recovery up to only 68% with 5 SSM pieces. Readily available organic substrates were not sufficient in the dewatering centrate, resulting in relatively low electric current density (mostly below 0.2 A/m 2 ). The slow electrode reaction did not provide sufficiently high pH conditions near the cathode for complete recovery of phosphorus as struvite. Based on these findings, additional experiments were conducted using stainless steel foil (SSF) as the cathode and acetate (12 mM) as an additional organic substrate for exoelectrogens at the bioanode. With the high electric current (>2 A/m 2 ), a thick layer of struvite crystals was formed on the SSF cathode. The phosphorus recovery increased to 96% with the increasing MEC operation time from 1 to 7 days. With the high phosphorus recovery, estimated energy requirement was relatively low at 13.8 kWh (with acetate) and 0.30 kWh (without acetate) to produce 1 kg struvite from dewatering centrate. For efficient phosphorus recovery from real wastewater, a foil-type cathode is recommended to avoid potential losses of small struvite crystals. Also, presence of readily

  13. Study on the water flooding in the cathode of direct methanol fuel cells.

    PubMed

    Im, Hun Suk; Kim, Sang-Kyung; Lim, Seongyop; Peck, Dong-Hyun; Jung, Doohwan; Hong, Won Hi

    2011-07-01

    Water flooding phenomena in the cathode of direct methanol fuel cells were analyzed by using electrochemical impedance spectroscopy. Two kinds of commercial gas diffusion layers with different PTFE contents of 5 wt% (GDL A5) and 20 wt% (GDL B20) were used to investigate the water flooding under various operating conditions. Water flooding was divided into two types: catalyst flooding and backing flooding. The cathode impedance spectra of each gas diffusion layer was obtained and compared under the same conditions. The diameter of the capacitive semicircle became larger with increasing current density for both, and this increase was greater for GDL B20 than GDL A5. Catalyst flooding is dominant and backing flooding is negligible when the air flow rate is high and current density is low. An equivalent model was suggested and fitted to the experimental data. Parameters for catalyst flooding and backing flooding were individually obtained. The capacitance of the catalyst layer decreases as the air flow rate decreases when the catalyst flooding is dominant.

  14. NEXIS Reservoir Cathode 2000 Hour Life Test

    NASA Technical Reports Server (NTRS)

    Vaughn, Jason; Schneider, Todd; Polk, Jay; Goebel, Dan; Ohlinger, Wayne; Hill, D. Norm

    2004-01-01

    The current design of the Nuclear Electric Xenon Ion System (NEXIS) employs a reservoir cathode as both the discharge and neutralizer cathode to meet the 10 yr thruster design life. The main difference between a reservoir cathode and a conventional discharge cathode is the source material (barium-containing compound) is contained within a reservoir instead of in an impregnated insert in the hollow tube. However, reservoir cathodes do not have much life test history associated with them. In order to demonstrate the feasibility of using a reservoir cathode as an integral part of the NEXIS ion thruster, a 2000 hr life test was performed. Several proof-of-concept (POC) reservoir cathodes were built early in the NEXIS program to conduct performance testing as well as life tests. One of the POC cathodes was sent to Marshall Space Flight Center (MSFC) where it was tested for 2000 hrs in a vacuum chamber. The cathode was operated at the NEXIS design point of 25 A discharge current and a xenon flow rate of 5.5 sccm during the 2000 hr test. The cathode performance parameters, including discharge current, discharge voltage, keeper current; keeper voltage, and flow rate were monitored throughout test. Also, the temperature upstream of cathode heater, the temperature downstream of the cathode heater, and the temperature of the orifice plate were monitored throughout the life of the test. The results of the 2000 hr test will be described in this paper. Included in the results will be time history of discharge current, discharge voltage, and flow rate. Also, a time history of the cathode temperature will be provided.

  15. Synthesis of low cost organometallic-type catalysts for their application in microbial fuel cell technology.

    PubMed

    Zerrouki, A; Salar-García, M J; Ortiz-Martínez, V M; Guendouz, S; Ilikti, H; de Los Ríos, A P; Hernández-Fernández, F J; Kameche, M

    2018-03-05

    Microbial fuel cells (MFCs) are a promising technology that generates electricity from several biodegradable substrates and wastes. The main drawback of these devices is the need of using a catalyst for the oxygen reduction reaction at the cathode, which makes the process relatively expensive. In this work, two low cost materials are tested as catalysts in MFCs. A novel iron complex based on the ligand n-phenyledenparaethoxy aniline has been synthesized and its performance as catalyst in single chamber MFCs containing ionic liquids has been compared with a commercial inorganic material such as Raney nickel. The results show that both materials are suitable for bioenergy production and wastewater treatment in the systems. Raney nickel cathodes allow MFCs to reach a maximum power output of 160 mW.m -3 anode , while the iron complex offers lower values. Regarding the wastewater treatment capacity, MFCs working with Raney nickel-based cathodes reach higher values of chemical oxygen demand removal (76%) compared with the performance displayed by the cathodes based on Fe-complex (56%).

  16. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2013-07-23

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  17. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2015-01-13

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  18. New insight into the discharge mechanism of silicon-air batteries using electrochemical impedance spectroscopy.

    PubMed

    Cohn, Gil; Eichel, Rüdiger A; Ein-Eli, Yair

    2013-03-07

    The mechanism of discharge termination in silicon-air batteries, employing a silicon wafer anode, a room-temperature fluorohydrogenate ionic liquid electrolyte and an air cathode membrane, is investigated using a wide range of tools. EIS studies indicate that the interfacial impedance between the electrolyte and the silicon wafer increases upon continuous discharge. In addition, it is shown that the impedance of the air cathode-electrolyte interface is several orders of magnitude lower than that of the anode. Equivalent circuit fitting parameters indicate the difference in the anode-electrolyte interface characteristics for different types of silicon wafers. Evolution of porous silicon surfaces at the anode and their properties, by means of estimated circuit parameters, is also presented. Moreover, it is found that the silicon anode potential has the highest negative impact on the battery discharge voltage, while the air cathode potential is actually stable and invariable along the whole discharge period. The discharge capacity of the battery can be increased significantly by mechanically replacing the silicon anode.

  19. Co-Flow Hollow Cathode Technology

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

    Hall thrusters utilize identical hollow cathode technology as ion thrusters, yet must operate at much higher mass flow rates in order to efficiently couple to the bulk plasma discharge. Higher flow rates are necessary in order to provide enough neutral collisions to transport electrons across magnetic fields so that they can reach the discharge. This higher flow rate, however, has potential life-limiting implications for the operation of the cathode. A solution to the problem involves splitting the mass flow into the hollow cathode into two streams, the internal and external flows. The internal flow is fixed and set such that the neutral pressure in the cathode allows for a high utilization of the emitter surface area. The external flow is variable depending on the flow rate through the anode of the Hall thruster, but also has a minimum in order to suppress high-energy ion generation. In the co-flow hollow cathode, the cathode assembly is mounted on thruster centerline, inside the inner magnetic core of the thruster. An annular gas plenum is placed at the base of the cathode and propellant is fed throughout to produce an azimuthally symmetric flow of gas that evenly expands around the cathode keeper. This configuration maximizes propellant utilization and is not subject to erosion processes. External gas feeds have been considered in the past for ion thruster applications, but usually in the context of eliminating high energy ion production. This approach is adapted specifically for the Hall thruster and exploits the geometry of a Hall thruster to feed and focus the external flow without introducing significant new complexity to the thruster design.

  20. Rotating cathode device for molten salt bath

    NASA Astrophysics Data System (ADS)

    1983-11-01

    The invention relates to a rotating cathode device for molten salt baths used to prepare metallic titanium or aluminum and the like by electrolysis of molten salts. The rotating cathode device is described. It is a cyclindrical cathode mounted on a rotating spindle, made of a lightweight material and mounted in such a way as to avoid thermal strain between the rotational shaft and the cylindrical cathode. At least one of the upper and lower ends of the cylindrical cathode are closed by a cap and a seal consisting of an inorganic fiber composite in the area between the cap and the cathode.

  1. Applications of Graphene-Modified Electrodes in Microbial Fuel Cells

    PubMed Central

    Yu, Fei; Wang, Chengxian; Ma, Jie

    2016-01-01

    Graphene-modified materials have captured increasing attention for energy applications due to their superior physical and chemical properties, which can significantly enhance the electricity generation performance of microbial fuel cells (MFC). In this review, several typical synthesis methods of graphene-modified electrodes, such as graphite oxide reduction methods, self-assembly methods, and chemical vapor deposition, are summarized. According to the different functions of the graphene-modified materials in the MFC anode and cathode chambers, a series of design concepts for MFC electrodes are assembled, e.g., enhancing the biocompatibility and improving the extracellular electron transfer efficiency for anode electrodes and increasing the active sites and strengthening the reduction pathway for cathode electrodes. In spite of the challenges of MFC electrodes, graphene-modified electrodes are promising for MFC development to address the reduction in efficiency brought about by organic waste by converting it into electrical energy. PMID:28773929

  2. Recycled tire crumb rubber anodes for sustainable power production in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Heming; Davidson, Matthew; Zuo, Yi; Ren, Zhiyong

    One of the greatest challenges facing microbial fuel cells (MFCs) in large scale applications is the high cost of electrode material. We demonstrate here that recycled tire crumb rubber coated with graphite paint can be used instead of fine carbon materials as the MFC anode. The tire particles showed satisfactory conductivity after 2-4 layers of coating. The specific surface area of the coated rubber was over an order of magnitude greater than similar sized graphite granules. Power production in single chamber tire-anode air-cathode MFCs reached a maximum power density of 421 mW m -2, with a coulombic efficiency (CE) of 25.1%. The control graphite granule MFC achieved higher power density (528 mW m -2) but lower CE (15.6%). The light weight of tire particle could reduce clogging and maintenance cost but posts challenges in conductive connection. The use of recycled material as the MFC anodes brings a new perspective to MFC design and application and carries significant economic and environmental benefit potentials.

  3. Hollow cathode, quasi-steady MPD arc

    NASA Technical Reports Server (NTRS)

    Parmentier, N.; Jahn, R. G.

    1971-01-01

    A quasi-steady MPD accelerator has been operated with four different hollow cathodes over a power range from 5 kilowatts to 5 megawatts. The absolute level of the argon mass flow, as well as the fractional division of the flow between the cathode and the six standard chamber injectors, is varied over a range of 1 to 12 grams per second. For a fixed total current, it is observed that the voltage increases monotonically with mass flow rate, compared to the usual experience with solid cathodes where the voltage decreases with mass flow rate. For a fixed percentage of flow through the cathode, each hollow cathode configuration displays a minimum impedance at a particular value of the total mass flow. It is asserted that in order to keep the discharge inside the hollow cathode the magnetic pressure and gasdynamic pressure have to match inside the cavity.

  4. Evaluation of the suitability and performance of cassava waste (peel) extracts in a microbial fuel cell for supplementary and sustainable energy production.

    PubMed

    Adekunle, Ademola; Raghavan, Vijaya

    2017-01-01

    In a number of energy-poor nations, peel from cassava processing represents one of the most abundant sources of lignocellulosic biomass. This peel is mostly discarded indiscriminately and eventually constitutes a problem to the environment. However, energy can be extracted from this peel in a microbial fuel cell. In this study, the viability of cassava peel extract as a substrate in a single-chamber air cathode microbial fuel cell is demonstrated, and optimum performance conditions are explored. The effects of different pretreatments on the extract are also discussed in the context of observed changes in the internal resistances, conductivity and Coulombic efficiencies. At the best conditions examined, the extract from cassava peel fermented for 168 h and adjusted to a pH of 7.63 attained a peak voltage of 687 mV ± 21 mV, a power density of 155 mW m -3 of reactor volume and a Coulombic efficiency of 11 %. Although this energy is limited to direct use, systems exist that can effectively harvest and boost the energy to levels sufficient for supplementary energy usage in cassava producing regions.

  5. Deactivation of Pt/VC proton exchange membrane fuel cell cathodes by SO2, H2S and COS

    NASA Astrophysics Data System (ADS)

    Gould, Benjamin D.; Baturina, Olga A.; Swider-Lyons, Karen E.

    Sulfur contaminants in air pose a threat to the successful operation of proton exchange membrane fuel cells (PEMFCs) via poisoning of the Pt-based cathodes. The deactivation behavior of commercial Pt on Vulcan carbon (Pt/VC) membrane electrode assemblies (MEAs) is determined when exposed to 1 ppm (dry) of SO 2, H 2S, or COS in air for 3, 12, and 24 h while held at a constant potential of 0.6 V. All the three sulfur compounds cause the same deactivation behavior in the fuel cell cathodes, and the polarization curves of the poisoned MEAs have the same decrease in performance. Sulfur coverages after multiple exposure times (3, 12, and 24 h) are determined by cyclic voltammetry (CV). As the exposure time to sulfur contaminants increases from 12 to 24 h, the sulfur coverage of the platinum saturates at 0.45. The sulfur is removed from the cathodes and their activity is partially restored both by cyclic voltammetry, as shown by others, and by successive polarization curves. Complete recovery of fuel cell performance is not achieved with either technique, suggesting that sulfur species permanently affect the surface of the catalyst.

  6. A survey of Kaufman thruster cathodes.

    NASA Technical Reports Server (NTRS)

    Weigand, A. J.; Nakanishi, S.

    1971-01-01

    A survey is presented of various cathodes which have been developed and used in the Kaufman ion thruster. The electron-bombardment type ion source used in the thruster is briefly described. The general design, operating characteristics, and power requirements are shown for each type of cathode from the refractory metals used in 1960 to the plasma discharge hollow cathodes of today. A detailed discussion of the hollow cathode is given describing starting and cyclic operating characteristics as well as more fundamental design parameters. Tests to date show that the plasma hollow cathode is an efficient electron source with demonstrated durability over 10,000 hours and should offer further performance and life improvements.

  7. Chlorobenzene Poisoning and Recovery of Platinum-Based Cathodes in Proton Exchange Membrane Fuel Cells

    PubMed Central

    Zhai, Yunfeng; Baturina, Olga; Ramaker, David; Farquhar, Erik; St-Pierre, Jean; Swider-Lyons, Karen

    2015-01-01

    The platinum electrocatalysts found in proton exchange membrane fuel cells are poisoned both reversibly and irreversibly by air pollutants and residual manufacturing contaminants. In this work, the poisoning of a Pt/C PEMFC cathode was probed by a trace of chlorobenzene in the air feed. Chlorobenzene inhibits the oxygen reduction reaction and causes significant cell performance loss. The performance loss is largely restored by neat air operation and potential cycling between 0.08 V and 1.2 V under H2/N2 (anode/cathode). The analysis of emissions, in situ X-ray absorption spectroscopy and electrochemical impedance spectra show the chlorobenzene adsorption/reaction and molecular orientation on Pt surface depend on the electrode potential. At low potentials, chlorobenzene deposits either on top of adsorbed H atoms or on the Pt surface via the benzene ring and is converted to benzene (ca. 0.1 V) or cyclohexane (ca. 0 V) upon Cl removal. At potentials higher than 0.2 V, chlorobenzene binds to Pt via the Cl atom and can be converted to benzene (less than 0.3 V) or desorbed. Cl− is created and remains in the membrane electrode assembly. Cl− binds to the Pt surface much stronger than chlorobenzene, but can slowly be flushed out by liquid water. PMID:26388963

  8. Cerium and niobium doped SrCoO3-δ as a potential cathode for intermediate temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Huang, Shouguo; Feng, Shuangjiu; Lu, Qiliang; Li, Yide; Wang, Hong; Wang, Chunchang

    2014-04-01

    Sr0.9Ce0.1Co0.9Nb0.1O3-δ (SCCN) has been synthesized using solid state reaction, and investigated as a new cathode material for intermediate temperature solid oxide fuel cells (ITSOFCs). SCCN material exhibits sufficiently high electronic conductivity and excellent chemical compatibility with SDC electrolyte. Highly charged Ce4+ and Nb5+ successfully stabilize the perovskite structure to avoid order-disorder phase transition. The electrical conductivity reaches a high value of 516 S cm-1 at 300 °C in air. The area specific resistances of the SCCN-50 wt.% Ce0.8Sm0.2O1.9 (SDC) cathode are as low as 0.027, 0.049, and 0.094 Ω cm2 at 700, 650, and 600 °C, respectively, with the corresponding peak power densities of 1074, 905, and 589 mW cm-2. A relatively low thermal expansion coefficient of SCCN-SDC is 14.3 × 10-6 K-1 in air. All these results imply that SCCN holds tremendous promise as a cathode material for ITSOFCs.

  9. Electricity generation from banana peels in an alkaline fuel cell with a Cu2O-Cu modified activated carbon cathode.

    PubMed

    Liu, Peng; Liu, Xianhua; Dong, Feng; Lin, Qingxia; Tong, Yindong; Li, Yang; Zhang, Pingping

    2018-08-01

    Low-cost and highly active catalyst for oxygen reduction reaction is of great importance in the design of alkaline fuel cells. In this work, Cu 2 O-Cu composite catalyst has been fabricated by a facile laser-irradiation method. The addition of Cu 2 O-Cu composite in activated carbon air-cathode greatly improves the performance of the cathode. Our results indicate the enhanced performance is likely attributed to the synergistic effect of high conductivity of Cu and the catalytic activity of Cu 2 O towards the oxygen reduction reaction. Furthermore, an alkaline fuel cell equipped with the composite air-cathode has been built to turn banana peels into electricity. Peak power density of 16.12Wm -2 is obtained under the condition of 3M KOH and 22.04gL -1 reducing sugar, which is higher than other reported low-temperature direct biomass alkaline fuel cells. HPLC results indicate the main oxidation products in the alkaline fuel cell were small organic acids. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Minimal RED cell pairs markedly improve electrode kinetics and power production in microbial reverse electrodialysis cells.

    PubMed

    Cusick, Roland D; Hatzell, Marta; Zhang, Fang; Logan, Bruce E

    2013-12-17

    Power production from microbial reverse electrodialysis cell (MRC) electrodes is substantially improved compared to microbial fuel cells (MFCs) by using ammonium bicarbonate (AmB) solutions in multiple RED cell pair stacks and the cathode chamber. Reducing the number of RED membranes pairs while maintaining enhanced electrode performance could help to reduce capital costs. We show here that using only a single RED cell pair (CP), created by operating the cathode in concentrated AmB, dramatically increased power production normalized to cathode area from both acetate (Acetate: from 0.9 to 3.1 W/m(2)-cat) and wastewater (WW: 0.3 to 1.7 W/m(2)), by reducing solution and charge transfer resistances at the cathode. A second RED cell pair increased RED stack potential and reduced anode charge transfer resistance, further increasing power production (Acetate: 4.2 W/m(2); WW: 1.9 W/m(2)). By maintaining near optimal electrode power production with fewer membranes, power densities normalized to total membrane area for the 1-CP (Acetate: 3.1 W/m(2)-mem; WW: 1.7 W/m(2)) and 2-CP (Acetate: 1.3 W/m(2)-mem; WW: 0.6 W/m(2)) reactors were much higher than previous MRCs (0.3-0.5 W/m(2)-mem with acetate). While operating at peak power, the rate of wastewater COD removal, normalized to reactor volume, was 30-50 times higher in 1-CP and 2-CP MRCs than that in a single chamber MFC. These findings show that even a single cell pair AmB RED stack can significantly enhance electrical power production and wastewater treatment.

  11. Simultaneous Wastewater Treatment, Algal Biomass Production and Electricity Generation in Clayware Microbial Carbon Capture Cells.

    PubMed

    Jadhav, Dipak A; Jain, Sumat C; Ghangrekar, Makarand M

    2017-11-01

    Performance of microbial carbon capture cells (MCCs), having a low-cost clayware separator, was evaluated in terms of wastewater treatment and electricity generation using algae Chlorella pyrenoidosa in MCC-1 and Anabaena ambigua in MCC-2 and without algae in a cathodic chamber of MCC-3. Higher power production was achieved in MCC-1 (6.4 W/m 3 ) compared to MCC-2 (4.29 W/m 3 ) and MCC-3 (3.29 W/m 3 ). Higher coulombic efficiency (15.23 ± 1.30%) and biomass production (66.4 ± 4.7 mg/(L*day)) in MCC-1 indicated the superiority of Chlorella over Anabaena algae for carbon capture and oxygen production to facilitate the cathodic reduction. Algal biofilm formation on the cathode surface of MCC-1 increased dissolved oxygen in the catholyte and decreased the cathodic charge transfer resistance with increase in reduction current. Electrochemical analyses revealed slow cathodic reactions and increase in internal resistance in MCC-2 (55 Ω) than MCC-1 (30 Ω), due to lower oxygen produced by Anabaena algae. Thus, biomass production in conjunction with wastewater treatment, CO 2 sequestration and electricity generation can be achieved using Chlorella algal biocathode in MCC.

  12. Cu2+ Dual-Doped Layer-Tunnel Hybrid Na0.6Mn1- xCu xO2 as a Cathode of Sodium-Ion Battery with Enhanced Structure Stability, Electrochemical Property, and Air Stability.

    PubMed

    Chen, Ting-Ru; Sheng, Tian; Wu, Zhen-Guo; Li, Jun-Tao; Wang, En-Hui; Wu, Chun-Jin; Li, Hong-Tai; Guo, Xiao-Dong; Zhong, Ben-He; Huang, Ling; Sun, Shi-Gang

    2018-03-28

    Sodium-ion batteries (SIBs) have been regarded as a promising candidate for large-scale renewable energy storage system. Layered manganese oxide cathode possesses the advantages of high energy density, low cost and natural abundance while suffering from limited cycling life and poor rate capacity. To overcome these weaknesses, layer-tunnel hybrid material was developed and served as the cathode of SIB, which integrated high capacity, superior cycle ability, and rate performance. In the current work, the doping of copper was adopted to suppress the Jahn-Teller effect of Mn 3+ and to affect relevant structural parameters. Multifunctions of the Cu 2+ doping were carefully investigated. It was found that the structure component ratio is varied with the Cu 2+ doping amount. Results demonstrated that Na + /vacancy rearrangement and phase transitions were suppressed during cycling without sacrificing the reversible capacity and enhanced electrochemical performances evidenced with 96 mA h g -1 retained after 250 cycles at 4 C and 85 mA h g -1 at 8 C. Furthermore, ex situ X-ray diffraction has demonstrated high reversibility of the Na 0.6 Mn 0.9 Cu 0.1 O 2 cathode during Na + extraction/insertion processes and superior air stability that results in better storage properties. This study reveals that the Cu 2+ doping could be an effective strategy to tune the properties and related performances of Mn-based layer-tunnel hybrid cathode.

  13. Composite cathode materials development for intermediate temperature solid oxide fuel cell systems

    NASA Astrophysics Data System (ADS)

    Qin, Ya

    Solid oxide fuel cell (SOFC) systems are of particular interest as electrochemical power systems that can operate on various hydrocarbon fuels with high fuel-to-electrical energy conversion efficiency. Within the SOFC stack, La0.8Sr 0.2Ga0.8Mg0.115Co0.085O3-delta (LSGMC) has been reported as an optimized composition of lanthanum gallate based electrolytes to achieve higher oxygen ionic conductivity at intermediate temperatures, i.e., 500-700°C. The electrocatalytic properties of interfaces between LSGMC electrolytes and various candidate intermediate-temperature SOFC cathodes have been investigated. Sm0.5Sr0.5CoO 3-delta (SSC), and La0.6Sr0.4Co0.2Fe 0.8O3-delta (LSCF), in both pure and composite forms with LSGMC, were investigated with regards to both oxygen reduction and evolution, A range of composite cathode compositions, having ratios of SSC (in wt.%) with LSGMC (wt.%) spanning the compositions 9:1, 8:2, 7:3, 6:4 and 5:5, were investigated to determine the optimal cathode-electrolyte interface performance at intermediate temperatures. All LSGMC electrolyte and cathode powders were synthesized using the glycine-nitrate process (GNP). Symmetrical electrochemical cells were investigated with three-electrode linear dc polarization and ac impedance spectroscopy to characterize the kinetics of the interfacial reactions in detail. Composite cathodes were found to perform better than the single phase cathodes due to significantly reduced polarization resistances. Among those composite SSC-LSGMC cathodes, the 7:3 composition has demonstrated the highest current density at the equivalent overpotential values, indicating that 7:3 is an optimal mixing ratio of the composite cathode materials to achieve the best performance. For the composite SC-LSGMC cathode/LSGMC interface, the cathodic overpotential under 1 A/cm2 current density was as low as 0.085 V at 700°C, 0.062V at 750°C and 0.051V at 800°C in air. Composite LSCF-LSGMC cathode/LSGMC interfaces were found to have

  14. Compact Rare Earth Emitter Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  15. Fuel cell stack with passive air supply

    DOEpatents

    Ren, Xiaoming; Gottesfeld, Shimshon

    2006-01-17

    A fuel cell stack has a plurality of polymer electrolyte fuel cells (PEFCs) where each PEFC includes a rectangular membrane electrode assembly (MEA) having a fuel flow field along a first axis and an air flow field along a second axis perpendicular to the first axis, where the fuel flow field is long relative to the air flow field. A cathode air flow field in each PEFC has air flow channels for air flow parallel to the second axis and that directly open to atmospheric air for air diffusion within the channels into contact with the MEA.

  16. Microbial quality of water in dental unit waterlines.

    PubMed

    Nikaeen, Mahnaz; Hatamzadeh, Maryam; Sabzevari, Zohre; Zareh, Omolbanin

    2009-09-01

    Dental unit waterlines (DUWLs) are ideal environment for development of microbial biofilms. Microbial contamination of water in DUWLs is thought to be the result of biofilm formation as it could serves as a haven for pathogens. The aim of this study was to assess microbial quality of water in dental unit waterlines of dental units located at the dental school of Isfahan University of Medical Sciences. Water samples were collected from air/water syringe and high-speed handpiece. Generally, 100-200 ml water samples were collected aseptically in sterile containers with sodium thiosulfate at the beginning of the day after a 2 minute purge. Samples were transferred to the laboratory in insulated box with cooling packs and examined for total viable heterotrophic bacteria and fungi. The heterotrophic plate count levels were significantly exceeded the American Dental Association recommendations for DUWL water quality (< 200 CFU/ml), in both air/water syringe (84%, CFU/ml: 500-20000) and high-speed handpiece (96%, CFU/ml: 710-36800) samples. However, there was no significant difference between the level of contamination in the air/water syringe and high-speed handpiece. Fungi were found in 28% and 36% of air/water syringe and high-speed handpiece samples, respectively; and filamentous fungi were the most frequently isolated fungi. DUWLs should be subjected to routine microbial monitoring and to a decontamination protocol in order to minimize the risk of exposure to potential pathogens from dental units.

  17. Multi-cathode unbalanced magnetron sputtering systems

    NASA Technical Reports Server (NTRS)

    Sproul, William D.

    1991-01-01

    Ion bombardment of a growing film during deposition is necessary in many instances to ensure a fully dense coating, particularly for hard coatings. Until the recent advent of unbalanced magnetron (UBM) cathodes, reactive sputtering had not been able to achieve the same degree of ion bombardment as other physical vapor deposition processes. The amount of ion bombardment of the substrate depends on the plasma density at the substrate, and in a UBM system the amount of bombardment will depend on the degree of unbalance of the cathode. In multi-cathode systems, the magnetic fields between the cathodes must be linked to confine the fast electrons that collide with the gas atoms. Any break in this linkage results in electrons being lost and a low plasma density. Modeling of the magnetic fields in a UBM cathode using a finite element analysis program has provided great insight into the interaction between the magnetic fields in multi-cathode systems. Large multi-cathode systems will require very strong magnets or many cathodes in order to maintain the magnetic field strength needed to achieve a high plasma density. Electromagnets offer the possibility of independent control of the plasma density. Such a system would be a large-scale version of an ion beam enhanced deposition (IBED) system, but, for the UBM system where the plasma would completely surround the substrate, the acronym IBED might now stand for Ion Blanket Enhanced Deposition.

  18. Microbial Challenge Testing of Single Liquid Cathode Feed Water Electrolysis Cells for the International Space Station (ISS) Oxygen Generator Assembly (OGA)

    NASA Technical Reports Server (NTRS)

    Roy, Robert J.; Wilson, Mark E.; Diderich, Greg S.; Steele, John W.

    2011-01-01

    The International Space Station (ISS) Oxygen Generator Assembly (OGA) operational performance may be adversely impacted by microbiological growth and biofilm formation over the electrolysis cell membranes. Biofilms could hinder the transport of water from the bulk fluid stream to the membranes and increase the cell concentration overpotential resulting in higher cell voltages and a shorter cell life. A microbial challenge test was performed on duplicate single liquid-cathode feed water electrolysis cells to evaluate operational performance with increasing levels of a mixture of five bacteria isolated from ISS and Space Shuttle potable water systems. Baseline performance of the single water electrolysis cells was determined for approximately one month with deionized water. Monthly performance was also determined following each inoculation of the feed tank with 100, 1000, 10,000 and 100,000 cells/ml of the mixed suspension of test bacteria. Water samples from the feed tank and recirculating water loops for each cell were periodically analyzed for enumeration and speciation of bacteria and total organic carbon. While initially a concern, this test program has demonstrated that the performance of the electrolysis cell is not adversely impacted by feed water containing the five species of bacteria tested at a concentration measured as high as 1,000,000 colony forming units (CFU)/ml. This paper presents the methodologies used in the conduct of this test program along with the performance test results at each level of bacteria concentration.

  19. Microbial Challenge Testing of Single Liquid Cathode Feed Water Electrolysis Cells for the International Space Station (ISS) Oxygen Generator Assembly (OGA)

    NASA Technical Reports Server (NTRS)

    Diderich, Greg S.; Roy, Robert J.; Steele, John W.; Van Keuren, Steven P.; Wilson, Mark E.

    2010-01-01

    The International Space Station (ISS) Oxygen Generator Assembly (OGA) operational performance may be adversely impacted by microbiological growth and biofilm formation over the electrolysis cell membranes. Biofilms could hinder the transport of water from the bulk fluid stream to the membranes and increase the cell resistance resulting in higher cell voltages and a shorter cell life. A microbial challenge test was performed on duplicate single liquid cathode feed electrolyzer cells to evaluate operational performance with increasing levels of a mixture of five bacteria isolated from ISS and Space Shuttle potable water systems. Baseline performance of the single water electrolysis cells was determined for approximately one month with deionized water. Monthly performance was also determined following each inoculation of the feed tank with 100, 1000, 10,000 and 100,000 cells/ml of the mixed suspension of test bacteria. Water samples from the feed tank and recirculating water loops for each cell were periodically analyzed for enumeration and speciation of bacteria and total organic carbon. While initially a concern, this test program has demonstrated that the performance of the electrolysis cell is not adversely impacted by feed water containing the five species of bacteria tested at a concentration measured as high as 1,000,000 colony forming units (CFU)/ml. This paper presents the methodologies used in the conduct of this test program along with the performance test results at each level of bacteria concentration.

  20. Hollow cathodes for arcjet thrusters

    NASA Technical Reports Server (NTRS)

    Luebben, Craig R.; Wilbur, Paul J.

    1987-01-01

    In an attempt to prevent exterior spot emission, hollow cathode bodies and orifice plates were constructed from boron nitride which is an electrical insulator, but the orifice plates melted and/or eroded at high interelectrode pressures. The most suitable hollow cathodes tested included a refractory metal orifice plate in a boron nitride body, with the insert insulated electrically from the orifice plate. In addition, the hollow cathode interior was evacuated to assure a low pressure at the insert surface, thus promoting diffuse electron emission. At high interelectrode pressures, the electrons tended to flow through the orifice plate rather than through the orifice, which could result in overheating of the orifice plate. Using a carefully aligned centerline anode, electron flow through the orifice could be sustained at interelectrode pressures up to 500 torr - but the current flow path still occasionally jumped from the orifice to the orifice plate. Based on these tests, it appears that a hollow cathode would operate most effectively at pressures in the arcjet regime with a refractory, chemically stable, and electrically insulating cathode body and orifice plate.

  1. RHETT/EPDM Flight Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Manzella, David; Patterson, Michael; Pastel, Michael

    1997-01-01

    Under the sponsorship of the BMDO Russian Hall Electric Thruster Technology program two xenon hollow cathodes, a flight unit and a flight spare were fabricated, acceptance tested and delivered to the Naval Research Laboratory for use on the Electric Propulsion Demonstration Module. These hollow cathodes, based on the International Space Station plasma contactor design, were fabricated at the NASA Lewis Research Center for use with a D-55 anode layer thruster in the first on-orbit operational application of this technology. The 2.2 Ampere nominal emission current of this device was obtained with a xenon flow rate of 0.6 mg/s. Ignition of the cathode discharge was accomplished through preheating the active electron emitter with a resistive heating element before application of a 650 volt ignition pulse between the emitter and an external starting electrode. The successful acceptance testing of the Electric Propulsion Demonstration Module utilizing these cathodes demonstrated the suitability of cathodes based on barium impregnated inserts in an enclosed keeper configuration for use with Hall thruster propulsion systems.

  2. Enhanced performance of hexavalent chromium reducing cathodes in the presence of Shewanella oneidensis MR-1 and lactate.

    PubMed

    Xafenias, Nikolaos; Zhang, Yue; Banks, Charles J

    2013-05-07

    Biocathodes for the reduction of the highly toxic hexavalent chromium (Cr(VI)) were investigated using Shewanella oneidensis MR-1 (MR-1) as a biocatalyst and performance was assessed in terms of current production and Cr(VI) reduction. Potentiostatically controlled experiments (-500 mV vs Ag/AgCl) showed that a mediatorless MR-1 biocathode started up under aerated conditions in the presence of lactate, received 5.5 and 1.7 times more electrons for Cr(VI) reduction over a 4 h operating period than controls without lactate and with lactate but without MR-1, respectively. Cr(VI) reduction was also enhanced, with a decrease in concentration over the 4 h operating period of 9 mg/L Cr(VI), compared to only 1 and 3 mg/L, respectively, in the controls. Riboflavin, an electron shuttle mediator naturally produced by MR-1, was also found to have a positive impact in potentiostatically controlled cathodes. Additionally, a microbial fuel cell (MFC) with MR-1 and lactate present in both anode and cathode produced a maximum current density of 32.5 mA/m(2) (1000 Ω external load) after receiving a 10 mg/L Cr(VI) addition in the cathode, and cathodic efficiency increased steadily over an 8 day operation period with successive Cr(VI) additions. In conclusion, effective and continuous Cr(VI) reduction with associated current production were achieved when MR-1 and lactate were both present in the biocathodes.

  3. Development program on a cold cathode electron gun

    NASA Technical Reports Server (NTRS)

    Spindt, C. A.; Holland, C. E.

    1985-01-01

    During this phase of the cathode development program, SRI improved the multiple electron beam exposure system used to print hole patterns for the cathode arrays, studied anisotropic etch processes, conducted cathode investigations using an emission microscope, reviewed possible alternate materials for cathode fabrication, studied cathode storage techniques, conducted high power operation experiments, and demonstrated high-current-density operation with small arrays of tips.

  4. LiAl xCo 1- xO 2 as 4 V cathodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Huang, Haitao; Rao, G. V. Subba; Chowdari, B. V. R.

    Nominal LiAl xCo 1- xO 2 with x ranging from 0.1 to 0.3 was prepared by heating mixture of Al(OH) 3, Co 3O 4 and LiOH at 750°C in air. The effect of substitution of non-transition metal, Al, in LiCoO 2 is investigated as a 4 V cathode for lithium ion. X-ray diffraction (XRD) indicates formation of a single phase (R3¯m) within this range of substitution. When cycled between 4.5 and 2.5 V vs. Li/Li + at a current density of 1 mA cm -2, the LiAl 0.15Co 0.85O 2 cathode exhibits reversible capacity of 160 mA h g -1 initially. XRD of the cathode made at the end of 10 cycles reveals no significant change on host structure.

  5. A Novel Cathode Material for Cathodic Dehalogenation of 1,1-Dibromo Cyclopropane Derivatives.

    PubMed

    Gütz, Christoph; Selt, Maximilian; Bänziger, Markus; Bucher, Christoph; Römelt, Christina; Hecken, Nadine; Gallou, Fabrice; Galvão, Tomás R; Waldvogel, Siegfried R

    2015-09-28

    Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane derivatives. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Arc initiation in cathodic arc plasma sources

    DOEpatents

    Anders, Andre

    2002-01-01

    A "triggerless" arc initiation method and apparatus is based on simply switching the arc supply voltage to the electrodes (anode and cathode). Neither a mechanical trigger electrode nor a high voltage flashover from a trigger electrode is required. A conducting path between the anode and cathode is provided, which allows a hot spot to form at a location where the path connects to the cathode. While the conductive path is eroded by the cathode spot action, plasma deposition ensures the ongoing repair of the conducting path. Arc initiation is achieved by simply applying the relatively low voltage of the arc power supply, e.g. 500 V-1 kV, with the insulator between the anode and cathode coated with a conducting layer and the current at the layer-cathode interface concentrated at one or a few contact points. The local power density at these contact points is sufficient for plasma production and thus arc initiation. A conductive surface layer, such as graphite or the material being deposited, is formed on the surface of the insulator which separates the cathode from the anode. The mechanism of plasma production (and arc initiation) is based on explosive destruction of the layer-cathode interface caused by joule heating. The current flow between the thin insulator coating and cathode occurs at only a few contact points so the current density is high.

  7. Microanalysis of extended-test xenon hollow cathodes

    NASA Technical Reports Server (NTRS)

    Verhey, Timothy R.; Patterson, Michael J.

    1991-01-01

    Four hollow cathode electron sources were analyzed via boroscopy, scanning electron microscopy, energy dispersive x ray analysis, and x ray diffraction analysis. These techniques were used to develop a preliminary understanding of the chemistry of the devices that arise from contamination due to inadequate feed-system integrity and improper insert activation. Two hollow cathodes were operated in an ion thruster simulator at an emission current of 23.0 A for approximately 500 hrs. The two tests differed in propellant-feed systems, discharge power supplies, and activation procedures. Tungsten deposition and barium tungstate formation on the internal cathode surfaces occurred during the first test, which were believed to result from oxygen contamination of the propellant feed-system. Consequently, the test facility was upgraded to reduce contamination, and the test was repeated. The second hollow cathode was found to have experienced significantly less tungsten deposition. A second pair of cathodes examined were the discharge and the neutralizer hollow cathodes used in a life-test of a 30-cm ring-cusp ion thruster at a 5.5 kW power level. The cathodes' test history was documented and the post-test microanalyses are described. The most significant change resulting from the life-test was substantial tungsten deposition on the internal cathode surfaces, as well as removal of material from the insert surface. In addition, barium tungstate and molybdate were found on insert surfaces. As a result of the cathode examinations, procedures and approaches were proposed for improved discharge ignition and cathode longevity.

  8. Low temperature aluminum reduction cell using hollow cathode

    DOEpatents

    Brown, Craig W.; Frizzle, Patrick B.

    2002-08-20

    A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte. A plurality of non-consumable anodes are disposed substantially vertically in the electrolyte along with a plurality of monolithic hollow cathodes. Each cathode has a top and bottom and the cathodes are disposed vertically in the electrolyte and the anodes and the cathodes are arranged in alternating relationship. Each of the cathodes is comprised of a first side facing a first opposing anode and a second side facing a second opposing anode. The first and second sides are joined by ends to form a reservoir in the hollow cathode for collecting aluminum therein deposited at the cathode.

  9. Design and characterization of a microbial fuel cell for the conversion of a lignocellulosic crop residue to electricity.

    PubMed

    Gregoire, K P; Becker, J G

    2012-09-01

    Agricultural crop residues contain high amounts of biochemical energy as cellulose and lignin. A portion of this biomass could be sustainably harvested for conversion to bioenergy to help offset fossil fuel consumption. In this study, the potential for converting lignocellulosic biomass directly to electricity in a microbial fuel cell (MFC) was explored. Design elements of tubular air cathode MFCs and leach-bed bioreactors were integrated to develop a new solid-substrate MFC in which cellulose hydrolysis, fermentation, and anode respiration occurred in a single chamber. Electricity was produced continuously from untreated corncob pellets for >60 d. Addition of rumen fluid increased power production, presumably by providing growth factors to anode-respiring bacteria. Periodic exposure to oxygen also increased power production, presumably by limiting the diversion of electrons to methanogenesis. In the absence of methanogenesis, bioaugmentation with Geobacter metallireducens further improved MFC performance. Under these conditions, the maximum power density was 230 mW/m(3). Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Granular activated carbon based microbial fuel cell for simultaneous decolorization of real dye wastewater and electricity generation.

    PubMed

    Kalathil, Shafeer; Lee, Jintae; Cho, Moo Hwan

    2011-12-15

    Decolorization of dye wastewater before discharge is pivotal because of its immense color and toxicities. In this study, a granular activated carbon based microbial fuel cell (GACB-MFC) was used without using any expensive materials like Nafion membrane and platinum catalyst for simultaneous decolorization of real dye wastewater and bioelectricity generation. After 48 hours of GACB-MFC operation, 73% color was removed at anode and 77% color was removed at cathode. COD removal was 71% at the anode and 76% at the cathode after 48 hours. Toxicity measurements showed that cathode effluent was almost nontoxic after 24 hours. The anode effluent was threefold less toxic compared to original dye wastewater after 48 hours. The GACB-MFC produced a power density of 1.7 W/m(3) with an open circuit voltage 0.45 V. One of the advantages of the GACB-MFC system is that pH was automatically adjusted from 12.4 to 7.2 and 8.0 at the anode and cathode during 48 hours operation. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Modelling potential/current distribution in microbial electrochemical systems shows how the optimal bioanode architecture depends on electrolyte conductivity.

    PubMed

    Lacroix, Rémy; Da Silva, Serge; Gaig, Monica Viaplana; Rousseau, Raphael; Délia, Marie-Line; Bergel, Alain

    2014-11-07

    The theoretical bases for modelling the distribution of the electrostatic potential in microbial electrochemical systems are described. The secondary potential distribution (i.e. without mass transport limitation of the substrate) is shown to be sufficient to validly address microbial electrolysis cells (MECs). MECs are modelled with two different ionic conductivities of the solution (1 and 5.3 S m(-1)) and two bioanode kinetics (jmax = 5.8 or 34 A m(-2)). A conventional reactor configuration, with the anode and the cathode face to face, is compared with a configuration where the bioanode perpendicular to the cathode implements the electrochemical reaction on its two sides. The low solution conductivity is shown to have a crucial impact, which cancels out the advantages obtained by setting the bioanode perpendicular to the cathode. For the same reason, when the surface area of the anode is increased by multiplying the number of plates, care must be taken not to create too dense anode architecture. Actually, the advantages of increasing the surface area by multiplying the number of plates can be lost through worsening of the electrochemical conditions in the multi-layered anode, because of the increase of the electrostatic potential of the solution inside the anode structure. The model gives the first theoretical bases for scaling up MECs in a rather simple but rigorous way.

  12. Reflective article having a sacrificial cathodic layer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kabagambe, Benjamin; Buchanan, Michael J.; Scott, Matthew S.

    The present invention relates to reflective articles, such as solar mirrors, that include a sacrificial cathodic layer. The reflective article, more particularly includes a substrate, such as glass, having a multi-layered coating thereon that includes a lead-free sacrificial cathodic layer. The sacrificial cathodic layer includes at least one transition metal, such as a particulate transition metal, which can be in the form of flakes (e.g., zinc flakes). The sacrificial cathodic layer can include an inorganic matrix formed from one or more organo-titanates. Alternatively, the sacrificial cathodic layer can include an organic polymer matrix (e.g., a crosslinked organic polymer matrix formedmore » from an organic polymer and an aminoplast crosslinking agent). The reflective article also includes an outer organic polymer coating, that can be electrodeposited over the sacrificial cathodic layer.« less

  13. Cold cathode vacuum gauging system

    DOEpatents

    Denny, Edward C.

    2004-03-09

    A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube. Measurement is made in the same manner as the prior cold cathode gauges in that the current through the anode to the cathode is measured as an indication of the pressure. By providing the portable magnetic assembly, a considerable savings in cost, installation, and maintenance of vacuum gauges for pressure measurement in a gas centrifuge cascade is realizable.

  14. Rechargeable lithium/polymer cathode batteries

    NASA Astrophysics Data System (ADS)

    Osaka, Tetsuya; Nakajima, Toshiki; Shiota, Koh; Owens, Boone B.

    1989-06-01

    Polypyrrole (PPy) and polyaniline (PAn) were investigated for cathode materials of rechargeable lithium batteries. PPy films prepared with PF6(-) anion and/or platinum substrate precoated with nitrile butadiene rubber (NBR) were excellent cathode materials because of rough and/or highly oriented film structure. PAn films were successfully prepared from non-aqueous propylene carbonate solution containing aniline, CF3COOH and lithium perchlorate. Its acidity strongly affects the anion doping-undoping behavior. The PAn cathode prepared in high acidic solution (e.g., 4:1 ratio of acid:aniline) gives the excellent battery performance.

  15. Effect of acclimatization on hexavalent chromium reduction in a biocathode microbial fuel cell.

    PubMed

    Wu, Xiayuan; Zhu, Xujun; Song, Tianshun; Zhang, Lixiong; Jia, Honghua; Wei, Ping

    2015-03-01

    A simple acclimatization method for the reduction of hexavalent chromium (Cr(VI)) at a biocathode by first enriching an exoelectrogenic biofilm on a microbial fuel cell (MFC) anode, followed by direct inversion of the anode to function as the biocathode, has been established. This novel method significantly enhanced the Cr(VI) reduction efficiency of the MFC, which was mainly attributed to the higher microbial density and less resistive Cr(III) precipitates on the cathode when compared with a common biocathode acclimatization method (control). The biocathode acclimatization period was shortened by 19days and the Cr(VI) reduction rate was increased by a factor of 2.9. Microbial community analyses of biocathodes acclimatized using different methods further verified the feasibility of this electrode inversion method, indicating similar dominant bacteria species in biofilms, which mainly consist of Gamma-proteobacteria and Bacteria. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Brewery and liquid manure wastewaters as potential feedstocks for microbial fuel cells: a performance study.

    PubMed

    Angosto, J M; Fernández-López, J A; Godínez, C

    2015-01-01

    This work aims at the comparison of the electrical and chemical performance of microbial fuel cells (MFCs) fed with several types of brewery and manure industrial wastewaters. Experiments were conducted in a single-cell MFC with the cathode exposed to air operated in batch and fed-batch modes. In fed-batch mode, after 4 days of operation, a standard MFC was refilled with crude wastewater to regenerate the biofilm and recreate initial feeding conditions. Brewery wastewater (CV1) mixed with pig-farm liquid manure (PU sample) gave the highest voltage (199.8 mV) and power density (340 mW/m3) outputs than non-mixed brewery waste water. Also, coulombic efficiency is much larger in the mixture (11%) than in the others (2-3%). However, in terms of chemical oxygen demand removal, the performance showed to be poorer (53%) for the mixed sample than in the pure brewery sample (93%). Fed-batch operation showed to be a good alternate for quasi-continuous operation, with equivalent electrical and chemical yields as compared with normal batchwise operation.

  17. Characterization of Hollow Cathode Performance and Thermal Behavior

    NASA Technical Reports Server (NTRS)

    Polk, James E.; Goebel, Dan M.; Watkins, Ron; Jameson, Kristina; Yoneshige, Lance; Przybylowski, JoHanna; Cho, Lauren

    2006-01-01

    Hollow cathodes are one of the main life-limiting components in ion engines and Hall thrusters. Although state-of-the-art hollow cathodes have demonstrated up to 30,352 hours of operation in ground tests with careful handling, future missions are likely to require longer life, more margin and greater resistance to reactive contaminant gases. Three alternate hollow cathode technologies that exploit different emitter materials or geometries to address some of the limitations of state-of-the-art cathodes are being investigated. Performance measurements of impregnated tungsten-iridium dispenser cathodes at discharge currents of 4 to 15 A demonstrated that they have the same operating range and ion production efficiency as conventional tungsten dispenser cathodes. Temperature measurements indicated that tungsten-iridium cathodes also operate at the same emitter temperatures. They did not exhibit the expected reduction in work function at the current densities tested. Hollow cathodes with lanthanum hexaboride emitters operated over a wide current range, but suffered from lower ion production efficiency at currents below about 12.4 A because of higher insert heating requirements. Differences in operating voltages and ion production rates are explained with a simple model of the effect of cathode parameters on discharge behavior.

  18. Zirconia coating stabilized super-iron alkaline cathodes

    NASA Astrophysics Data System (ADS)

    Yu, Xingwen; Licht, Stuart

    A low-level zirconia coating significantly stabilizes high energy alkaline super-iron cathodes, and improves the energy storage capacity of super-iron batteries. Zirconia coating is derived from ZrCl 4 in an organic medium through the conversion of ZrCl 4 to ZrO 2. In alkaline battery system, ZrO 2 provides an intact shield for the cathode materials and the hydroxide shuttle through the coating sustains alkaline cathode redox chemistry. Most super-iron cathodes are solid-state stable, such as K 2FeO 4 and Cs 2FeO 4, but tend to be passivated in alkaline electrolyte due to the formation of Fe(III) over layer. Zirconia coating effectively enhances the stability of these super-iron cathodes. However, for solid-state unstable super-iron cathode (e.g. BaFeO 4), only a little stabilization effect of zirconia coating is observed.

  19. Mechanistic insights for the development of Li-O2 battery materials: addressing Li2O2 conductivity limitations and electrolyte and cathode instabilities.

    PubMed

    McCloskey, Bryan D; Burke, Colin M; Nichols, Jessica E; Renfrew, Sara E

    2015-08-18

    The Li-air battery has received significant attention over the past decade given its high theoretical specific energy compared to competing energy storage technologies. Yet, numerous scientific challenges remain unsolved in the pursuit of attaining a battery with modest Coulombic efficiency and high capacity. In this Feature Article, we provide our current perspective on challenges facing the development of nonaqueous Li-O2 battery cathodes. We initially present a review on our understanding of electrochemical processes occurring at the nonaqueous Li-O2 cathode. Electrolyte and cathode instabilities and Li2O2 conductivity limitations are then discussed, and suggestions for future materials research development to alleviate these issues are provided.

  20. Compatibility between strontium-doped ferrite cathode and metallic interconnects in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Miguel-Pérez, Verónica; Martínez-Amesti, Ana; Arriortua, María Isabel

    2015-04-01

    One of the most important issues related to the performance of solid oxide fuel cells (SOFCs) is the chromium poisoning of the perovskite-type materials used as cathodes by the gaseous chromium species from metallic interconnects. In this study, powder mixtures of LSF40-Cr2O3 were heated at 800 °C and 1000 °C in air and were subsequently analysed by X-ray powder diffraction. For all the mixtures, the crystallisation of SrCrO4 was observed. In addition, the degradation occurring between three alloys with different compositions, Crofer 22 APU, SS430 and Conicro 4023 W 188, as metallic interconnects and La0.6Sr0.4FeO3 (LSF40) ceramic material as a cathode was studied. The results show significant chromium deposition and the formation of SrCrO4, LaCrO3 and La2O3 that block the active LSF40 electrode surface and degrade the stack (YSZ/SDC/LSF40/Interconnect) performance. LSF40 assembled with SS430 exhibited substantial Cr deposition. The deposition of the Cr species and the reaction with the LSF40 cathode is related to the composition of the oxide scales formed at each metallic interconnect and at the same time is related to the composition of the alloys. The best results obtained were for the half-cell (YSZ/SDC/LSF40) in contact with Conicro 4023 W 188 and Crofer 22 APU after heat treatment in air at 800 °C for 100 h.

  1. Effect of mobile unidirectional air flow unit on microbial contamination of air in standard urologic procedures.

    PubMed

    Ferretti, Stefania; Pasquarella, Cesira; Fornia, Samanta; Saccani, Elisa; Signorelli, Carlo; Vitali, Pietro; Sansebastiano, Giuliano Ezio

    2009-12-01

    Infection is one of the most feared complications of surgery. New instrumentation is being developed to reduce deposition of bacteria. We investigated 45 major surgical procedures (21 radical nephrectomies [RN] and 24 radical retropubic prostatectomies [RRP]) in our urology department during 2007. In about one-half of the interventions, an ultraclean air flow mobile (UAF) unit was used. Bacterial sedimentation was evaluated by nitrocellulose membranes placed on the instrument tray and by settle plates positioned at four points in the operating room. In 27 operations, an additional membrane was located near the incision. Bacterial counts on the nitrocellulose membranes during RN were 230 colony-forming units (cfu)/m(2)/h with the UAF unit and 2,254 cfu/m(2)/h without the unit (p = 0.001). During RRP, the values were 288 cfu/m(2)/h and 3,126 cfu/m(2)/h respectively (p = 0.001). The membrane placed near the incision during RN showed a microbial count of 1,235 cfu/m(2)/h with the UAF unit and 5,093 cfu/m(2)/h without the unit (p = 0.002); during RRP, the values were 1,845 cfu/m(2)/h and 3,790 cfu/m(2)/h, respectively (difference not significant). Bacterial contamination detected by settle plates during RN showed a mean value of 2,273 cfu/m(2)/h when the UAF unit was used and 2,054 cfu/m(2)/h without the unit; during RRP, the values were 2,332 cfu/m(2)/h and 2,629 cfu/m(2)/h with and without the UAF unit, respectively (NS). No statistically significant differences were detected in the clinical data registered in patients operated on under standard conditions and while the UAF unit was functioning. The UAF appears able to reduce microbial contamination at the operating table, reaching a bacterial number obtained in ultraclean operating theatres.

  2. Enhanced ambient stability of efficient perovskite solar cells by employing a modified fullerene cathode interlayer

    DOE PAGES

    Zhu, Zonglong; Chueh, Chu -Chen; Lin, Francis; ...

    2016-03-22

    A novel fullerene cathode interlayer is employed to facilitate the fabrication of stable and efficient perovskite solar cells. Here, this modified fullerene surfactant significantly increases air stability of the derived devices due to its hydrophobic characteristics to enable 80% of the initial PCE to be retained after being exposed in ambient condition with 20% relative humidity for 14 days.

  3. A novel self-powered and sensitive label-free DNA biosensor in microbial fuel cell.

    PubMed

    Asghary, Maryam; Raoof, Jahan Bakhsh; Rahimnejad, Mostafa; Ojani, Reza

    2016-08-15

    In this work, a novel self-powered, sensitive, low-cost, and label-free DNA biosensor is reported by applying a two-chambered microbial fuel cell (MFC) as a power supply. A graphite electrode and an Au nanoparticles modified graphite electrode (AuNP/graphite electrode) were used as anode and cathode in the MFC system, respectively. The active biocatalyst in the anodic chamber was a mixed culture of microorganisms. The sensing element of the biosensor was fabricated by the well-known Au-thiol binding the ssDNA probe on the surface of an AuNP/graphite cathode. Electrons produced by microorganisms were transported from the anode to the cathode through an external circuit, which could be detected by the terminal multi-meter detector. The difference between power densities of the ssDNA probe modified cathode in the absence and presence of complementary sequence served as the detection signal of the DNA hybridization with detection limit of 3.1nM. Thereafter, this biosensor was employed for diagnosis and determination of complementary sequence in a human serum sample. The hybridization specificity studies further revealed that the developed DNA biosensor could distinguish fully complementary sequences from one-base mismatched and non-complementary sequences. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Environmental Sources of Bacteria Differentially Influence Host-Associated Microbial Dynamics.

    PubMed

    Cardona, Cesar; Lax, Simon; Larsen, Peter; Stephens, Brent; Hampton-Marcell, Jarrad; Edwardson, Christian F; Henry, Chris; Van Bonn, Bill; Gilbert, Jack A

    2018-01-01

    Host-associated microbial dynamics are influenced by dietary and immune factors, but how exogenous microbial exposure shapes host-microbe dynamics remains poorly characterized. To investigate this phenomenon, we characterized the skin, rectum, and respiratory tract-associated microbiota in four aquarium-housed dolphins daily over a period of 6 weeks, including administration of a probiotic during weeks 4 to 6. The environmental bacterial sources were also characterized, including the animals' human handlers, the aquarium air and water, and the dolphins' food supply. Continuous microbial exposure occurred between all sites, yet each environment maintained a characteristic microbiota, suggesting that the majority of exposure events do not result in colonization. Small changes in water physicochemistry had a significant but weak correlation with change in dolphin-associated bacterial richness but had no influence on phylogenetic diversity. Food and air microbiota were the richest and had the largest conditional influence on other microbiota in the absence of probiotics, but during probiotic administration, food alone had the largest influence on the stability of the dolphin microbiota. Our results suggest that respiratory tract and gastrointestinal epithelium interactions with air- and food-associated microbes had the biggest influence on host-microbiota dynamics, while other interactions, such as skin transmission, played only a minor role. Finally, direct oral stimulation with a foreign exogenous microbial source can have a profound effect on microbial stability. IMPORTANCE These results provide valuable insights into the ecological influence of exogenous microbial exposure, as well as laying the foundation for improving aquarium management practices. By comparing data for dolphins from aquaria that use natural versus artificial seawater, we demonstrate the potential influence of aquarium water disinfection procedures on dolphin microbial dynamics.

  5. Simultaneous electricity generation and microbially-assisted electrosynthesis in ceramic MFCs.

    PubMed

    Gajda, Iwona; Greenman, John; Melhuish, Chris; Ieropoulos, Ioannis

    2015-08-01

    To date, the development of microbially assisted synthesis in Bioelectrochemical Systems (BESs) has focused on mechanisms that consume energy in order to drive the electrosynthesis process. This work reports--for the first time--on novel ceramic MFC systems that generate electricity whilst simultaneously driving the electrosynthesis of useful chemical products. A novel, inexpensive and low maintenance MFC demonstrated electrical power production and implementation into a practical application. Terracotta based tubular MFCs were able to produce sufficient power to operate an LED continuously over a 7 day period with a concomitant 92% COD reduction. Whilst the MFCs were generating energy, an alkaline solution was produced on the cathode that was directly related to the amount of power generated. The alkaline catholyte was able to fix CO2 into carbonate/bicarbonate salts. This approach implies carbon capture and storage (CCS), effectively capturing CO2 through wet caustic 'scrubbing' on the cathode, which ultimately locks carbon dioxide. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Effect of cathode cooling efficiency and oxygen plasma gas pressure on the hafnium cathode wall temperature

    NASA Astrophysics Data System (ADS)

    Ashtekar, Koustubh; Diehl, Gregory; Hamer, John

    2012-10-01

    The hafnium cathode is widely used in DC plasma arc cutting (PAC) under an oxygen gas environment to cut iron and iron alloys. The hafnium erosion is always a concern which is controlled by the surface temperature. In this study, the effect of cathode cooling efficiency and oxygen gas pressure on the hafnium surface temperature are quantified. The two layer cathode sheath model is applied on the refractive hafnium surface while oxygen species (O2, O, O+, O++, e-) are considered within the thermal dis-equilibrium regime. The system of non-linear equations comprising of current density balance, heat flux balance at both the cathode surface and the sheath-ionization layer is coupled with the plasma gas composition solver. Using cooling heat flux, gas pressure and current density as inputs; the cathode wall temperature, electron temperature, and sheath voltage drop are calculated. Additionally, contribution of emitted electron current (Je) and ions current (Ji) to the total current flux are estimated. Higher gas pressure usually reduces Ji and increases Je that reduces the surface temperature by thermionic cooling.

  7. Lithium-Air Cell Development

    NASA Technical Reports Server (NTRS)

    Reid, Concha M.; Dobley, Arthur; Seymour, Frasier W.

    2014-01-01

    Lithium-air (Li-air) primary batteries have a theoretical specific capacity of 11,400 Wh/kg, the highest of any common metal-air system. NASA is developing Li-air technology for a Mobile Oxygen Concentrator for Spacecraft Emergencies, an application which requires an extremely lightweight primary battery that can discharge over 24 hours continuously. Several vendors were funded through the NASA SBIR program to develop Li-air technology to fulfill the requirements of this application. New catalysts and carbon cathode structures were developed to enhance the oxygen reduction reaction and increase surface area to improve cell performance. Techniques to stabilize the lithium metal anode surface were explored. Experimental results for prototype laboratory cells are given. Projections are made for the performance of hypothetical cells constructed from the materials that were developed.

  8. Microbial fuel cell operation using monoazo and diazo dyes as terminal electron acceptor for simultaneous decolourisation and bioelectricity generation.

    PubMed

    Oon, Yoong-Sin; Ong, Soon-An; Ho, Li-Ngee; Wong, Yee-Shian; Oon, Yoong-Ling; Lehl, Harvinder Kaur; Thung, Wei-Eng; Nordin, Noradiba

    2017-03-05

    Monoazo and diazo dyes [New coccine (NC), Acid orange 7 (AO7), Reactive red 120 (RR120) and Reactive green 19 (RG19)] were employed as electron acceptors in the abiotic cathode of microbial fuel cell. The electrons and protons generated from microbial organic oxidation at the anode which were utilized for electrochemical azo dye reduction at the cathodic chamber was successfully demonstrated. When NC was employed as the electron acceptor, the chemical oxygen demand (COD) removal and dye decolourisation efficiencies obtained at the anodic and cathodic chamber were 73±3% and 95.1±1.1%, respectively. This study demonstrated that the decolourisation rates of monoazo dyes were ∼50% higher than diazo dyes. The maximum power density in relation to NC decolourisation was 20.64mW/m 2 , corresponding to current density of 120.24mA/m 2 . The decolourisation rate and power output of different azo dyes were in the order of NC>AO7>RR120>RG19. The findings revealed that the structure of dye influenced the decolourisation and power performance of MFC. Azo dye with electron-withdrawing group at para substituent to azo bond would draw electrons from azo bond; hence the azo dye became more electrophilic and more favourable for dye reduction. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. A novel high energy density rechargeable lithium/air battery.

    PubMed

    Zhang, Tao; Imanishi, Nobuyuki; Shimonishi, Yuta; Hirano, Atsushi; Takeda, Yasuo; Yamamoto, Osamu; Sammes, Nigel

    2010-03-14

    A novel rechargeable lithium/air battery was fabricated, which consisted of a water-stable multilayer Li-metal anode, acetic acid-water electrolyte, and a fuel-cell analogous air-diffusion cathode and possessed a high energy density of 779 W h kg(-1), twice that of the conventional graphite/LiCoO(2) cell.

  10. Matrix Cathode Development

    DTIC Science & Technology

    1976-01-01

    18 2.3.1 Cross-Sections 18 2.3.2 Surface Finishing 27 2.3.3 Hardness and Ductility 27 2.3.4 Defects and Imperfections 30 2.3.4.1 Cauliflower ...ATHODE CRIMPED DOWN EARS NICKEL HEATER Figure 4. The Cylindrical Cathode as Proposed by G. Haas. It is a l/S1 Nickel Cylinder wit^ a Blind Hole...Machined in One End and A Heater Inserted. The Cathode is Fixed to the Blind End by Crimping Down Ears . L± !V ,-.■...■ I-’"«:-, . mUtmr

  11. Extended-testing of xenon ion thruster hollow cathodes

    NASA Technical Reports Server (NTRS)

    Sarver-Verhey, Timothy R.

    1992-01-01

    A hollow cathode wear-test of 508 hours was successfully completed at an emission current of 23.0 A and a xenon flow rate of 10 Pa-L/s. This test was the continuation of a hollow cathode contamination investigation. Discharge voltage was stable at 16.7 V. The cathode temperature averaged 1050 C with a 7 percent drop during the wear-test. Discharge ignition voltage was found to be approximately 20 V and was repeatable over four starts. Post-test analyses of the hollow cathode found a much improved internal cathode condition with respect to earlier wear-test cathodes. Negligible tungsten movement occurred and no formation of mono-barium tungsten was observed. These results correlated with an order-of-magnitude reduction in propellant feed-system leakage rate. Ba2CaWO6 and extensive calcium crystal formation occurred on the upstream end of the insert. Ba-Ca compound depositions were found on the Mo insert collar, on the Re electrical leads, and in the gap between the insert and cathode wall. This wear-test cathode was found to be in the best internal condition and had the most stable operating performance of any hollow cathode tested during this contamination investigation.

  12. Virtual cathode microwave generator having annular anode slit

    DOEpatents

    Kwan, Thomas J. T.; Snell, Charles M.

    1988-01-01

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit therethrough effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators.

  13. Surface-Tuned Co3O4 Nanoparticles Dispersed on Nitrogen-Doped Graphene as an Efficient Cathode Electrocatalyst for Mechanical Rechargeable Zinc-Air Battery Application.

    PubMed

    Singh, Santosh K; Dhavale, Vishal M; Kurungot, Sreekumar

    2015-09-30

    The most vital component of the fuel cells and metal-air batteries is the electrocatalyst, which can facilitate the oxygen reduction reaction (ORR) at a significantly reduced overpotential. The present work deals with the development of surface-tuned cobalt oxide (Co3O4) nanoparticles dispersed on nitrogen-doped graphene as a potential ORR electrocatalyst possessing some unique advantages. The thermally reduced nitrogen-doped graphene (NGr) was decorated with three different morphologies of Co3O4 nanoparticles, viz., cubic, blunt edged cubic, and spherical, by using a simple hydrothermal method. We found that the spherical Co3O4 nanoparticle supported NGr catalyst (Co3O4-SP/NGr-24h) has acquired a significant activity makeover to display the ORR activity closely matching with the state-of-the-art Pt supported carbon (PtC) catalyst in alkaline medium. Subsequently, the Co3O4-SP/NGr-24h catalyst has been utilized as the air electrode in a Zn-air battery, which was found to show comparable performance to the system derived from PtC. Co3O4-SP/NGr-24h catalyst has shown several hours of flat discharge profile at the discharge rates of 10, 20, and 50 mA/cm(2) with a specific capacity and energy density of ~590 mAh/g-Zn and ~840 Wh/kg-Zn, respectively, in the primary Zn-air battery system. In conjunction, Co3O4-SP/NGr-24h has outperformed as an air electrode in mechanical rechargeable Zn-air battery as well, which has shown consistent flat discharge profile with minimal voltage loss at a discharge rate of 50 mA/cm(2). The present results, thus demonstrate that the proper combination of the tuned morphology of Co3O4 with NGr will be a promising and inexpensive material for efficient and ecofriendly cathodes for Zn-air batteries.

  14. Multi-cathode metal vapor arc ion source

    DOEpatents

    Brown, Ian G.; MacGill, Robert A.

    1988-01-01

    An ion generating apparatus utilizing a vacuum chamber, a cathode and an anode in the chamber. A source of electrical power produces an arc or discharge between the cathode and anode. The arc is sufficient to vaporize a portion of the cathode to form a plasma. The plasma is directed to an extractor which separates the electrons from the plasma, and accelerates the ions to produce an ion beam. One embodiment of the appaatus utilizes a multi-cathode arrangement for interaction with the anode.

  15. Robust Low-Cost Cathode for Commercial Applications

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.

    2007-01-01

    Under funding from the NASA Commercial Technology Office, a cathode assembly was designed, developed, fabricated, and tested for use in plasma sources for ground-based materials processing applications. The cathode development activity relied on the large prior NASA investment and successful development of high-current, high-efficiency, long-life hollow cathodes for use on the International Space Station Plasma Contactor System. The hollow cathode was designed and fabricated based on known engineering criteria and manufacturing processes for compatibility with the requirements of the plasma source. The transfer of NASA GRC-developed hollow cathode technology for use as an electron emitter in the commercial plasma source is anticipated to yield a significant increase in process control, while eliminating the present issues of electron emitter lifetime and contamination.

  16. Filtered cathodic arc source

    DOEpatents

    Falabella, Steven; Sanders, David M.

    1994-01-01

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45.degree. to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

  17. Emission current control system for multiple hollow cathode devices

    NASA Technical Reports Server (NTRS)

    Beattie, John R. (Inventor); Hancock, Donald J. (Inventor)

    1988-01-01

    An emission current control system for balancing the individual emission currents from an array of hollow cathodes has current sensors for determining the current drawn by each cathode from a power supply. Each current sensor has an output signal which has a magnitude proportional to the current. The current sensor output signals are averaged, the average value so obtained being applied to a respective controller for controlling the flow of an ion source material through each cathode. Also applied to each controller are the respective sensor output signals for each cathode and a common reference signal. The flow of source material through each hollow cathode is thereby made proportional to the current drawn by that cathode, the average current drawn by all of the cathodes, and the reference signal. Thus, the emission current of each cathode is controlled such that each is made substantially equal to the emission current of each of the other cathodes. When utilized as a component of a multiple hollow cathode ion propulsion motor, the emission current control system of the invention provides for balancing the thrust of the motor about the thrust axis and also for preventing premature failure of a hollow cathode source due to operation above a maximum rated emission current.

  18. Microbial Impact on Success of Human Exploration Missions

    NASA Technical Reports Server (NTRS)

    Pierson, Duane L.; Ott, C. Mark; Groves, T. O.; Paloski, W. H. (Technical Monitor)

    2000-01-01

    The purpose of this study is to identify microbiological risks associated with space exploration and identify potential countermeasures available. Identification of microbial risks associated with space habitation requires knowledge of the sources and expected types of microbial agents. Crew data along with environmental data from water, surfaces, air, and free condensate are utilized in risk examination. Data from terrestrial models are also used. Microbial risks to crew health include bacteria, fungi, protozoa, and viruses. Adverse effects of microbes include: infections, allergic reactions, toxin production, release of volatiles, food spoilage, plant disease, material degradation, and environmental contamination. Risk is difficult to assess because of unknown potential changes in microbes (e.g., mutation) and the human host (e.g., immune changes). Prevention of adverse microbial impacts is preferred over remediation. Preventative measures include engineering measures (e.g., air filtration), crew microbial screening, acceptability standards, and active verification by onboard monitoring. Microbiological agents are important risks to human health and performance during space flight and risks increase with mission duration. Acceptable risk level must be defined. Prevention must be given high priority. Careful screening of crewmembers and payloads is an important element of any risk mitigation plan. Improved quantitation of microbiological risks is a high priority.

  19. Preliminary Results of Field Emission Cathode Tests

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Kovaleski, Scott D.

    2001-01-01

    Preliminary screening tests of field emission cathodes such as chemical vapor deposited (CVD) diamond, textured pyrolytic graphite, and textured copper were conducted at background pressures typical of electric thruster test facilities to assess cathode performance and stability. Very low power electric thrusters which provide tens to hundreds micronewtons of thrust may need field emission neutralizers that have a capability of tens to hundreds of microamperes. From current voltage characteristics, it was found that the CVD diamond and textured metals cathodes clearly satisfied the Fowler-Nordheim emission relation. The CVD diamond and a textured copper cathode had average current densities of 270 and 380 mA/sq cm, respectively, at the beginning-of-life. After a few hours of operation the cathode emission currents degraded by 40 to 75% at background pressures in the 10(exp -5) Pa to 10(exp -4) Pa range. The textured pyrolytic graphite had a modest current density at beginning-of-life of 84 mA/sq cm, but this cathode was the most stable of all. Extended testing of the most promising cathodes is warranted to determine if current degradation is a burn-in effect or whether it is a long-term degradation process. Preliminary experiments with ferroelectric emission cathodes, which are ceramics with spontaneous electric polarization, were conducted. Peak current densities of 30 to 120 mA/sq cm were obtained for pulse durations of about 500 ns in the 10(exp -4) Pa pressure range.

  20. Time-resolved ion energy and charge state distributions in pulsed cathodic arc plasmas of Nb‑Al cathodes in high vacuum

    NASA Astrophysics Data System (ADS)

    Zöhrer, Siegfried; Anders, André; Franz, Robert

    2018-05-01

    Cathodic arcs have been utilized in various applications including the deposition of thin films and coatings, ion implantation, and high current switching. Despite substantial progress in recent decades, the physical mechanisms responsible for the observed plasma properties are still a matter of dispute, particularly for multi-element cathodes, which can play an essential role in applications. The analysis of plasma properties is complicated by the generally occurring neutral background of metal atoms, which perturbs initial ion properties. By using a time-resolved method in combination with pulsed arcs and a comprehensive Nb‑Al cathode model system, we investigate the influence of cathode composition on the plasma, while making the influence of neutrals visible for the observed time frame. The results visualize ion detections of 600 μs plasma pulses, extracted 0.27 m from the cathode, resolved in mass-per-charge, energy-per-charge and time. Ion properties are found to be strongly dependent on the cathode material in a way that cannot be deduced by simple linear extrapolation. Subsequently, current hypotheses in cathodic arc physics applying to multi-element cathodes, like the so-called ‘velocity rule’ or the ‘cohesive energy rule’, are tested for early and late stages of the pulse. Apart from their fundamental character, the findings could be useful in optimizing or designing plasma properties for applications, by actively utilizing effects on ion distributions caused by composite cathode materials and charge exchange with neutrals.

  1. Novel RuCoSe as non-platinum catalysts for oxygen reduction reaction in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Rozenfeld, Shmuel; Schechter, Michal; Teller, Hanan; Cahan, Rivka; Schechter, Alex

    2017-09-01

    Microbial electrochemical cells (MECs) are explored for the conversion of acetate directly to electrical energy. This device utilizes a Geobacter sulfurreducens anode and a novel RuCoSe air cathode. RuCoSe synthesized in selected compositions by a borohydride reduction method produces amorphous structures of powdered agglomerates. Oxygen reduction reaction (ORR) was measured in a phosphate buffer solution pH 7 using a rotating disc electrode (RDE), from which the kinetic current (ik) was measured as a function of potential and composition. The results show that ik of RuxCoySe catalysts increases in the range of XRu = 0.25 > x > 0.7 and y < 0.15 for all tested potentials. A poisoning study of RuCoSe and Pt catalysts in a high concentration acetate solution shows improved tolerance of RuCoSe to this fuel at acetate concentration ≥500 mM. MEC discharge plots under physiological conditions show that ∼ RuCo2Se (sample S3) has a peak power density of 750 mW cm-2 which is comparable with Pt 900 mW cm-2.

  2. Environmental microbial contamination in a stem cell bank.

    PubMed

    Cobo, F; Concha, A

    2007-04-01

    The aim of this study was to evaluate the main environmental microbial contaminants of the clean rooms in our stem cell bank. We have measured the microbial air contamination by both passive and active air sampling and the microbial monitoring of surfaces by means of Rodac plates. The environmental monitoring tests were carried out in accordance with the guidelines of European Pharmacopeia and US Pharmacopeia. The micro-organisms were identified by means of an automated system (VITEK 2). During the monitoring, the clean rooms are continually under good manufacturing practices specifications. The most frequent contaminants were Gram-positive cocci. The main contaminants in our stem cell bank were coagulase-negative staphylococci and other opportunistic human pathogens. In order to assure the levels of potential contamination in both embryonic and adult stem cell lines, a continuous sampling of air particles and testing for viable microbiological contamination is necessary. This study is the first evaluation of the environmental contaminants in stem cell banks and can serve as initial evaluation for these establishments. The introduction of environmental monitoring programmes in the processing of stem cell lines could diminish the risk of contamination in stem cell cultures.

  3. Microbial Photoelectrosynthesis for Self-Sustaining Hydrogen Generation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lu, Lu; Williams, Nicholas B.; Turner, John A.

    Current artificial photosynthesis (APS) systems are promising for the storage of solar energy via transportable and storable fuels, but the anodic half-reaction of water oxidation is an energy intensive process which in many cases poorly couples with the cathodic half-reaction. Here in this paper, we demonstrate a self-sustaining microbial photoelectrosynthesis (MPES) system that pairs microbial electrochemical oxidation with photoelectrochemical water reduction for energy efficient H 2 generation. MPES reduces the overall energy requirements thereby greatly expanding the range of semiconductors that can be utilized in APS. Due to the recovery of chemical energy from waste organics by the mild microbialmore » process and utilization of cost-effective and stable catalyst/electrode materials, our MPES system produced a stable current of 0.4 mA/cm 2 for 24 h without any external bias and ~10 mA/cm 2 with a modest bias under one sun illumination. Finally, this system also showed other merits, such as creating benefits of wastewater treatment and facile preparation and scalability.« less

  4. Microbial Photoelectrosynthesis for Self-Sustaining Hydrogen Generation

    DOE PAGES

    Lu, Lu; Williams, Nicholas B.; Turner, John A.; ...

    2017-10-17

    Current artificial photosynthesis (APS) systems are promising for the storage of solar energy via transportable and storable fuels, but the anodic half-reaction of water oxidation is an energy intensive process which in many cases poorly couples with the cathodic half-reaction. Here in this paper, we demonstrate a self-sustaining microbial photoelectrosynthesis (MPES) system that pairs microbial electrochemical oxidation with photoelectrochemical water reduction for energy efficient H 2 generation. MPES reduces the overall energy requirements thereby greatly expanding the range of semiconductors that can be utilized in APS. Due to the recovery of chemical energy from waste organics by the mild microbialmore » process and utilization of cost-effective and stable catalyst/electrode materials, our MPES system produced a stable current of 0.4 mA/cm 2 for 24 h without any external bias and ~10 mA/cm 2 with a modest bias under one sun illumination. Finally, this system also showed other merits, such as creating benefits of wastewater treatment and facile preparation and scalability.« less

  5. Microbial fuel cells coupling with the three-dimensional electro-Fenton technique enhances the degradation of methyl orange in the wastewater.

    PubMed

    Huang, Tao; Liu, Longfei; Tao, Junjun; Zhou, Lulu; Zhang, Shuwen

    2018-04-23

    The emission of the source effluent of azo dyes has resulted in a serial of environmental problems including of the direct damage of the natural esthetics, the inhibition of the oxygen exchange, the shortage of the photosynthesis, and the reduction of the aquatic flora and fauna. A bioelectrochemical platform (3D-EF-MFCs) combining two-chamber microbial fuel cells and three dimensional electro-Fenton technique were delicately designed and assembled to explore the decolorization, bio-genericity performance of the methyl orange, and the possible biotic-abiotic degradation mechanisms. The 3D-EF-MFCs processes showed higher decolorization efficiencies, COD removals, and better bioelectricity performance than the pure electro-Fenton-microbial fuel cell (EF-MFC) systems. The two-chamber experiments filling with the granular activated carbons were better than the single-chamber packing system on the whole. The moderate increase of Fe 2+ ions dosing in the cathode chamber accelerated the formation of •OH, which further enhanced the degradation of the methyl orange (MO). The cathode-decolorization and COD removals were decreased with the increase of MO concentration. However, the degradation performance of MO was indirectly improved in the anode compartment at the same conditions. The bed electrodes played a mediator role in the anode and cathode chambers, certainly elevated the voltage output and the power density, and lowered the internal impedance of EF-MFC process.

  6. Performance of mixed-species biocathode microbial fuel cells using saline mustard tuber wastewater as self-buffered catholyte.

    PubMed

    Guo, Fei; Fu, Guokai; Zhang, Zhi

    2015-03-01

    Mixed-species biocathode microbial fuel cells (MFCs) were constructed. Mustard tuber wastewater (MTWW) was used as catholyte. Simultaneous organic matters and nitrogen removal at the cathode was observed, and majority of contaminants reduced were accomplished within acclimating period (AP). Concerning nitrogen removal, aerobic and anaerobic microenvironment could be formed within the cathodic biofilms, and both heterotrophic denitrification and bioelectrochemical denitrification were involved. Also, it was demonstrated that organic matters and ammonium could have detrimental effects on voltage output, but it could retrieve finally. Similar maximum power densities were obtained during stage1 (1.20Wm(-3)), stage2 (1.24Wm(-3)) and stage3 (1.32Wm(-3)). However, overpotential for oxygen reduction was investigated due to lower bacteria activity at cathode, which could major limitation for energy recovery. Considering similar performance of MFCs during different stages, it could be concluded that MTWW was adequately self-buffered when used as catholyte at mixed-species biocathodes. Copyright © 2015. Published by Elsevier Ltd.

  7. Filtered cathodic arc source

    DOEpatents

    Falabella, S.; Sanders, D.M.

    1994-01-18

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge is described. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45[degree] to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles. 3 figures.

  8. Time evolution of nanosecond runaway discharges in air and helium at atmospheric pressure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yatom, S.; Vekselman, V.; Krasik, Ya. E.

    2012-12-15

    Time- and space-resolved fast framing photography was employed to study the discharge initiated by runaway electrons in air and He gas at atmospheric pressure. Whereas in the both cases, the discharge occurs in a nanosecond time scale and its front propagates with a similar velocity along the cathode-anode gap, the later stages of the discharge differ significantly. In air, the main discharge channels develop and remain in the locations with the strongest field enhancement. In He gas, the first, diode 'gap bridging' stage, is similar to that obtained in air; however, the development of the discharge that follows is dictatedmore » by an explosive electron emission from micro-protrusions on the edge of the cathode. These results allow us to draw conclusions regarding the different conductivity of the plasma produced in He and air discharges.« less

  9. Metal-Free Carbon-Based Materials: Promising Electrocatalysts for Oxygen Reduction Reaction in Microbial Fuel Cells

    PubMed Central

    Sawant, Sandesh Y.; Han, Thi Hiep; Cho, Moo Hwan

    2016-01-01

    Microbial fuel cells (MFCs) are a promising green approach for wastewater treatment with the simultaneous advantage of energy production. Among the various limiting factors, the cathodic limitation, with respect to performance and cost, is one of the main obstacles to the practical applications of MFCs. Despite the high performance of platinum and other metal-based cathodes, their practical use is limited by their high cost, low stability, and environmental toxicity. Oxygen is the most favorable electron acceptor in the case of MFCs, which reduces to water through a complicated oxygen reduction reaction (ORR). Carbon-based ORR catalysts possessing high surface area and good electrical conductivity improve the ORR kinetics by lowering the cathodic overpotential. Recently, a range of carbon-based materials have attracted attention for their exceptional ORR catalytic activity and high stability. Doping the carbon texture with a heteroatom improved their ORR activity remarkably through the favorable adsorption of oxygen and weaker molecular bonding. This review provides better insight into ORR catalysis for MFCs and the properties, performance, and applicability of various metal-free carbon-based electrocatalysts in MFCs to find the most appropriate cathodic catalyst for the practical applications. The approaches for improvement, key challenges, and future opportunities in this field are also explored. PMID:28029116

  10. Development of plasma cathode electron guns

    NASA Astrophysics Data System (ADS)

    Oks, Efim M.; Schanin, Peter M.

    1999-05-01

    The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

  11. Understanding the Role of Temperature and Cathode Composition on Interface and Bulk: Optimizing Aluminum Oxide Coatings for Li-Ion Cathodes.

    PubMed

    Han, Binghong; Paulauskas, Tadas; Key, Baris; Peebles, Cameron; Park, Joong Sun; Klie, Robert F; Vaughey, John T; Dogan, Fulya

    2017-05-03

    Surface coating of cathode materials with Al 2 O 3 has been shown to be a promising method for cathode stabilization and improved cycling performance at high operating voltages. However, a detailed understanding on how coating process and cathode composition change the chemical composition, morphology, and distribution of coating within the cathode interface and bulk lattice is still missing. In this study, we use a wet-chemical method to synthesize a series of Al 2 O 3 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 and LiCoO 2 cathodes treated under various annealing temperatures and a combination of structural characterization techniques to understand the composition, homogeneity, and morphology of the coating layer and the bulk cathode. Nuclear magnetic resonance and electron microscopy results reveal that the nature of the interface is highly dependent on the annealing temperature and cathode composition. For Al 2 O 3 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 , higher annealing temperature leads to more homogeneous and more closely attached coating on cathode materials, corresponding to better electrochemical performance. Lower Al 2 O 3 coating content is found to be helpful to further improve the initial capacity and cyclability, which can greatly outperform the pristine cathode material. For Al 2 O 3 -coated LiCoO 2 , the incorporation of Al into the cathode lattice is observed after annealing at high temperatures, implying the transformation from "surface coatings" to "dopants", which is not observed for LiNi 0.5 Co 0.2 Mn 0.3 O 2 . As a result, Al 2 O 3 -coated LiCoO 2 annealed at higher temperature shows similar initial capacity but lower retention compared to that annealed at a lower temperature, due to the intercalation of surface alumina into the bulk layered structure forming a solid solution.

  12. Diagnostics of cathode material loss in cutting plasma torch

    NASA Astrophysics Data System (ADS)

    Gruber, J.; Šonský, J.; Hlína, J.

    2014-07-01

    A cutting plasma torch was observed in several ways by a high-speed camera with a focus on the cathode area. In the first experiment, the plasma arc between the nozzle tip and anode was recorded in a series of duty cycles ranging from new unworn cathodes to cathode failure due to wear and material loss. In the second experiment, we used a specially modified nozzle to observe the inside area between the cathode and the nozzle exit through a fused silica window. Finally, using tilted view, we observed a pool of molten hafnium at the cathode tip during the plasma torch operation. The process of cathode material melting, droplet formation, their expulsion and rate of cathode material loss was examined.

  13. Improving performance of MFC by design alteration and adding cathodic electrolytes.

    PubMed

    Jadhav, G S; Ghangrekar, M M

    2008-12-01

    Performance of two microbial fuel cells (MFCs) was investigated under batch and continuous mode of operation using different cathodic electrolyte. The wastewater was supplied from the bottom port provided to the anode chamber in both the MFCs and the effluent left the anode chamber from the top port in MFC-1, whereas in MFC-2, the effluent exit was provided close to membrane. Stainless steel (SS) mesh anode was used in both the MFCs with surface area of 167 and 100 cm(2) in MFC-1 and MFC-2, respectively. Under batch mode and continuous mode of operation, these MFCs gave chemical oxygen demand removal efficiency more than 85% and about 68%, respectively. Under batch mode of operation, maximum power density of 39.95 and 56.87 mW/m(2) and maximum current density of 180.83 and 295 mA/m(2) were obtained in MFC-1 and MFC-2, respectively. Under continuous mode of operation, a reduction in power and current density was observed. Even with less surface area of the anode, MFC-2 produced more current (1.77 mA) than MFC-1 (1.40 mA). Among the cathodic electrolyte tested, these can be listed in decreasing order of power density as aerated KMnO(4) solution > KMnO(4) solution without aeration > aerated tap water > aerated tap water with NaCl.

  14. High current density cathode for electrorefining in molten electrolyte

    DOEpatents

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  15. Aeromicrobiology/air quality

    USGS Publications Warehouse

    Andersen, Gary L.; Frisch, A.S.; Kellogg, Christina A.; Levetin, E.; Lighthart, Bruce; Paterno, D.

    2009-01-01

    The most prevalent microorganisms, viruses, bacteria, and fungi, are introduced into the atmosphere from many anthropogenic sources such as agricultural, industrial and urban activities, termed microbial air pollution (MAP), and natural sources. These include soil, vegetation, and ocean surfaces that have been disturbed by atmospheric turbulence. The airborne concentrations range from nil to great numbers and change as functions of time of day, season, location, and upwind sources. While airborne, they may settle out immediately or be transported great distances. Further, most viable airborne cells can be rendered nonviable due to temperature effects, dehydration or rehydration, UV radiation, and/or air pollution effects. Mathematical microbial survival models that simulate these effects have been developed.

  16. Long-Term Cr Poisoning Effect on LSCF-GDC Composite Cathodes Sintered at Different Temperatures

    DOE PAGES

    Xiong, Chunyan; Taillon, Joshua A.; Pellegrinelli, Christopher; ...

    2016-07-19

    Here, the impact of sintering temperature on Cr-poisoning of solid oxide fuel cell (SOFC) cathodes was systematically studied. La 0.6Sr 0.4Fe 0.8Co 0.2O 3-δ - Ce 0.9Gd 0.1O 2-δ symmetric cells were aged at 750°C in synthetic air with the presence of Crofer 22 APU, a common high temperature interconnect, over 200 hours and electrochemical impedance spectroscopy (EIS) was used to determine the degradation process. Both the ohmic resistance (R Ω) and polarization resistance (R P) of LSCF-GDC cells, extracted from EIS spectra, for different sintering temperatures increase as a function of aging time. Furthermore, the Cr-related degradation rate increasesmore » with decreased cathode sintering temperature. The polarization resistance of cathode sintered at lower temperature (950°C) increases dramatically while aging with the presence of Cr and also significantly decreases the oxygen partial pressure dependence after aging. The degradation rate shows a positive correlation to the concentration of Cr. The results indicate that decreased sintering temperature increases the total surface area, leading to more available sites for Sr-Cr-O nucleation and thus greater Cr degradation.« less

  17. Li- and Mn-Rich Cathode Materials: Challenges to Commercialization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zheng, Jianming; Myeong, Seungjun; Cho, Woongrae

    2016-12-14

    The lithium- and manganese-rich (LMR) layered structure cathode exhibit one of the highest specific energy (~900 Wh kg-1) among all the cathode materials. However, the practical applications of LMR cathodes are still hindered by several significant challenges including voltage fade, large initial capacity loss, poor rate capability and limited cycle life. Herein, we review the recent progresses and understandings on the application of LMR cathode materials from practical point of view. Several key parameters of LMR cathodes that affect the LMR/graphite full cell operation are systematically analysed. These factors include the first cycle capacity loss, voltage fade, powder tap density,more » electrode density of LMR based cathode etc. New approaches to minimize the detrimental effect of these factors are highlighted in this work. We also provided the perspectives for the future research on LMR cathode materials, focusing on addressing the fundamental problems of LMR cathodes while always keeping practical considerations in mind.« less

  18. Halotolerant extremophile bacteria from the Great Salt Lake for recycling pollutants in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Grattieri, Matteo; Suvira, Milomir; Hasan, Kamrul; Minteer, Shelley D.

    2017-07-01

    The treatment of hypersaline wastewater (approximately 5% of the wastewater worldwide) cannot be performed by classical biological techniques. Herein the halotolerant extremophile bacteria obtained from the Great Salt Lake (Utah) were explored in single chamber microbial fuel cells with Pt-free cathodes for more than 18 days. The bacteria samples collected in two different locations of the lake (Stansbury Bay and Antelope Island) showed different electrochemical performances. The maximum achieved power output of 36 mW m-2 was from the microbial fuel cell based on the sample originated from Stansbury Bay, at a current density of 820 mA m-2. The performances throughout the long-term operation are discussed and a bioelectrochemical mechanism is proposed.

  19. Simultaneous carbon and nitrogen removal using an oxic/anoxic-biocathode microbial fuel cells coupled system.

    PubMed

    Xie, Shan; Liang, Peng; Chen, Yang; Xia, Xue; Huang, Xia

    2011-01-01

    A coupled microbial fuel cell (MFC) system comprising of an oxic-biocathode MFC (O-MFC) and an anoxic-biocathode MFC (A-MFC) was implemented for simultaneous removal of carbon and nitrogen from a synthetic wastewater. The chemical oxygen demand (COD) of the influent was mainly reduced at the anodes of the two MFCs; ammonium was oxidized to nitrate in the O-MFC's cathode, and nitrate was electrochemically denitrified in the A-MFC's cathode. The coupled MFC system reached power densities of 14 W/m(3) net cathodic compartment (NCC) and 7.2 W/m(3) NCC for the O-MFC and the A-MFC, respectively. In addition, the MFC system obtained a maximum COD, NH(4)(+)-N and TN removal rate of 98.8%, 97.4% and 97.3%, respectively, at an A-MFC external resistance of 5 Ω, a recirculation ratio (recirculated flow to total influent flow) of 2:1, and an influent flow ratio (O-MFC anode flow to A-MFC anode flow) of 1:1. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Lithium air batteries having ether-based electrolytes

    DOEpatents

    Amine, Khalil; Curtiss, Larry A.; Lu, Jun; Lau, Kah Chun; Zhang, Zhengcheng; Sun, Yang-Kook

    2016-10-25

    A lithium-air battery includes a cathode including a porous active carbon material, a separator, an anode including lithium, and an electrolyte including a lithium salt and polyalkylene glycol ether, where the porous active carbon material is free of a metal-based catalyst.