Design of optimum solid oxide membrane electrolysis cells for metals production

DOE PAGES

Guan, Xiaofei; Pal, Uday B.

2015-12-24

Oxide to metal conversion is one of the most energy-intensive steps in the value chain for metals production. Solid oxide membrane (SOM) electrolysis process provides a general route for directly reducing various metal oxides to their respective metals, alloys, or intermetallics. Because of its lower energy use and ability to use inert anode resulting in zero carbon emission, SOM electrolysis process emerges as a promising technology that can replace the state-of-the-art metals production processes. In this paper, a careful study of the SOM electrolysis process using equivalent DC circuit modeling is performed and correlated to the experimental results. Finally, amore » discussion on relative importance of each resistive element in the circuit and on possible ways of lowering the rate-limiting resistive elements provides a generic guideline for designing optimum SOM electrolysis cells.« less

Clean hydrogen generation through the electrocatalytic oxidation of ethanol in a Proton Exchange Membrane Electrolysis Cell (PEMEC): Effect of the nature and structure of the catalytic anode

NASA Astrophysics Data System (ADS)

Lamy, Claude; Jaubert, Thomas; Baranton, Stève; Coutanceau, Christophe

2014-01-01

The electrocatalytic oxidation of ethanol was investigated in a Proton Exchange Membrane Electrolysis Cell (PEMEC) working at low temperature (20°C) on several Pt-based catalysts (Pt/C, PtSn/C, PtSnRu/C) in order to produce very clean hydrogen by electrolysis of a biomass compound. The electrocatalytic activity was determined by cyclic voltammetry and the rate of hydrogen evolution was measured for each catalyst at different current densities. The cell voltages UEtOH were recorded as a function of time for each current density. At 100 mA cm-2, i.e. 0.5 A with the 5 cm2 surface area PEMEC used, the cell voltage did not exceed 0.9 V for an evolution rate of about 220 cm3 of hydrogen per hour and the electrical energy consumed was less than 2.3 kWh (Nm3)-1, i.e. less than one half of the energy needed for water electrolysis (4.7 kWh (Nm3)-1 at UH2O = 2 V). This result is valid for the decomposition of any organic compound, particularly those originated from biomass resource, provided that their electro-oxidation rate is sufficient (>100 mA cm-2) at a relatively low cell voltage (Ucell < 1 V) which necessitates the development of efficient electrocatalysts for the electrochemical decomposition of this compound.

Evaluation of hydrogen production and internal resistance in forward osmosis membrane integrated microbial electrolysis cells.

PubMed

Lee, Mi-Young; Kim, Kyoung-Yeol; Yang, Euntae; Kim, In S

2015-01-01

In order to enhance hydrogen production by facilitated proton transport through a forward osmosis (FO) membrane, the FO membrane was integrated into microbial electrolysis cells (MECs). An improved hydrogen production rate was obtained in the FO-MEC (12.5±1.84×10(-3)m(3)H2/m(3)/d) compared to that of the cation exchange membrane (CEM) - MEC (4.42±0.04×10(-3)m(3)H2/m(3)/d) during batch tests (72h). After an internal resistance analysis, it was confirmed that the enhanced hydrogen production in FO-MEC was attributed to the smaller charge transfer resistance than in the CEM-MEC (90.3Ω and 133.4Ω respectively). The calculation of partial internal resistance concluded that the transport resistance can be substantially reduced by replacing a CEM with a FO membrane; decrease of the resistance from 0.069Ωm(2) to 5.99×10(-4)Ωm(2). Copyright © 2015 Elsevier Ltd. All rights reserved.

Polymer electrolyte membrane water electrolysis: Restraining degradation in the presence of fluctuating power

NASA Astrophysics Data System (ADS)

Rakousky, Christoph; Reimer, Uwe; Wippermann, Klaus; Kuhri, Susanne; Carmo, Marcelo; Lueke, Wiebke; Stolten, Detlef

2017-02-01

Polymer electrolyte membrane (PEM) water electrolysis generates 'green' hydrogen when conducted with electricity from renewable - but fluctuating - sources like wind or solar photovoltaic. Unfortunately, the long-term stability of the electrolyzer performance is still not fully understood under these input power profiles. In this study, we contrast the degradation behavior of our PEM water electrolysis single cells that occurs under operation with constant and intermittent power and derive preferable operating states. For this purpose, five different current density profiles are used, of which two were constant and three dynamic. Cells operated at 1 A cm-2 show no degradation. However, degradation was observed for the remaining four profiles, all of which underwent periods of high current density (2 A cm-2). Hereby, constant operation at 2 A cm-2 led to the highest degradation rate (194 μV h-1). Degradation can be greatly reduced when the cells are operated with an intermittent profile. Current density switching has a positive effect on durability, as it causes reversible parts of degradation to recover and results in a substantially reduced degradation per mole of hydrogen produced. Two general degradation phenomena were identified, a decreased anode exchange current density and an increased contact resistance at the titanium porous transport layer (Ti-PTL).

CeO2-Y2O3-ZrO2 Membrane with Enhanced Molten Salt Corrosion Resistance for Solid Oxide Membrane (SOM) Electrolysis Process

NASA Astrophysics Data System (ADS)

Zou, Xingli; Li, Xin; Shen, Bin; Lu, Xionggang; Xu, Qian; Zhou, Zhongfu; Ding, Weizhong

2017-02-01

Innovative CeO2-Y2O3-ZrO2 membrane has been successfully developed and used in the solid oxide membrane (SOM) electrolysis process for green metallic materials production. The x mol pct ceria/(8- x) mol pct yttria-costabilized zirconia ( xCe(8- x)YSZ, x = 0, 1, 4, or 7) membranes have been fabricated and investigated as the membrane-based inert anodes to control the SOM electroreduction process in molten salt. The characteristics of these fabricated xCe(8- x)YSZ membranes including their corrosion resistances in molten salt and their degradation mechanisms have been systematically investigated and compared. The results show that the addition of ceria in the YSZ-based membrane can inhibit the depletion of yttrium during the SOM electrolysis, which thus makes the ceria-reinforced YSZ-based membranes possess enhanced corrosion resistances to molten salt. The ceria/yttria-costabilized zirconia membranes can also provide reasonable oxygen ion conductivity during electrolysis. Further investigation shows that the newly modified 4Ce4YSZ ceramic membrane has the potential to be used as novel inert SOM anode for the facile and sustainable production of metals/alloys/composites materials such as Si, Ti5Si3, TiC, and Ti5Si3/TiC from their metal oxides precursors in molten CaCl2.

Field-scale electrolysis/ceramic membrane system for the treatment of sewage from decentralized small communities.

PubMed

Son, Dong-Jin; Kim, Woo-Yeol; Yun, Chan-Young; Kim, Dae-Gun; Chang, Duk; Sunwoo, Young; Hong, Ki-Ho

2017-07-05

The electrolysis process adopting copper electrodes and ceramic membrane with pore sizes of 0.1-0.2 μm were consisted to a system for the treatment of sewage from decentralized small communities. The system was operated under an HRT of 0.1 hour, voltage of 24 V, and TMP of 0.05 MPa. The system showed average removals of organics, nitrogen, phosphorus, and solids of up to 80%, 52%, 92%, and 100%, respectively. Removal of organics and nitrogen dramatically increased in proportion to increment of influent loading. Phosphorus and solids were remarkably eliminated by both electro-coagulation and membrane filtration. The residual particulate constituents could also be removed successfully through membrane process. A system composed of electrolysis process with ceramic membrane would be a compact, reliable, and flexible option for the treatment of sewage from decentralized small communities.

Energy-Efficient and Environmentally Friendly Solid Oxide Membrane Electrolysis Process for Magnesium Oxide Reduction: Experiment and Modeling

NASA Astrophysics Data System (ADS)

Guan, Xiaofei; Pal, Uday B.; Powell, Adam C.

2014-06-01

This paper reports a solid oxide membrane (SOM) electrolysis experiment using an LSM(La0.8Sr0.2MnO3-δ)-Inconel inert anode current collector for production of magnesium and oxygen directly from magnesium oxide at 1423 K (1150 °C). The electrochemical performance of the SOM cell was evaluated by means of various electrochemical techniques including electrochemical impedance spectroscopy, potentiodynamic scan, and electrolysis. Electronic transference numbers of the flux were measured to assess the magnesium dissolution in the flux during SOM electrolysis. The effects of magnesium solubility in the flux on the current efficiency and the SOM stability during electrolysis are discussed. An inverse correlation between the electronic transference number of the flux and the current efficiency of the SOM electrolysis was observed. Based on the experimental results, a new equivalent circuit of the SOM electrolysis process is presented. A general electrochemical polarization model of SOM process for magnesium and oxygen gas production is developed, and the maximum allowable applied potential to avoid zirconia dissociation is calculated as well. The modeling results suggest that a high electronic resistance of the flux and a relatively low electronic resistance of SOM are required to achieve membrane stability, high current efficiency, and high production rates of magnesium and oxygen.

Anion exchange membrane

DOEpatents

Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

2013-05-07

An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

Determination of the efficiency of ethanol oxidation in a proton exchange membrane electrolysis cell

NASA Astrophysics Data System (ADS)

Altarawneh, Rakan M.; Majidi, Pasha; Pickup, Peter G.

2017-05-01

Products and residual ethanol in the anode and cathode exhausts of an ethanol electrolysis cell (EEC) have been analyzed by proton NMR and infrared spectrometry under a variety of operating conditions. This provides a full accounting of the fate of ethanol entering the cell, including the stoichiometry of the ethanol oxidation reaction (i.e. the average number of electrons transferred per ethanol molecule), product distribution and the crossover of ethanol and products through the membrane. The reaction stoichiometry (nav) is the key parameter that determines the faradaic efficiency of both EECs and direct ethanol fuel cells. Values determined independently from the product distribution, amount of ethanol consumed, and a simple electrochemical method based on the dependence of the current on the flow rate of the ethanol solution are compared. It is shown that the electrochemical method yields results that are consistent with those based on the product distribution, and based on the consumption of ethanol when crossover is accounted for. Since quantitative analysis of the cathode exhaust is challenging, the electrochemical method provides a valuable alternative for routine determination of nav, and hence the faradaic efficiency of the cell.

Towards developing a backing layer for proton exchange membrane electrolyzers

NASA Astrophysics Data System (ADS)

Lettenmeier, P.; Kolb, S.; Burggraf, F.; Gago, A. S.; Friedrich, K. A.

2016-04-01

Current energy policies require the urgent replacement of fossil energy carriers by carbon neutral ones, such as hydrogen. The backing or micro-porous layer plays an important role in the performance of hydrogen proton exchange membrane (PEM) fuel cells, reducing contact resistance and improving reactant/product management. Such carbon-based coating cannot be used in PEM electrolysis since it oxidizes to CO2 at high voltages. A functional titanium macro-porous layer (MPL) on the current collectors of a PEM electrolyzer is developed by thermal spraying. It improves the contact with the catalyst layers by ca. 20 mΩ cm2, increasing significantly the efficiency of the device when operating at high current densities.

Low-Energy Catalytic Electrolysis for Simultaneous Hydrogen Evolution and Lignin Depolymerization.

PubMed

Du, Xu; Liu, Wei; Zhang, Zhe; Mulyadi, Arie; Brittain, Alex; Gong, Jian; Deng, Yulin

2017-03-09

Here, a new proton-exchange-membrane electrolysis is presented, in which lignin was used as the hydrogen source at the anode for hydrogen production. Either polyoxometalate (POM) or FeCl 3 was used as the catalyst and charge-transfer agent at the anode. Over 90 % Faraday efficiency was achieved. In a thermal-insulation reactor, the heat energy could be maintained at a very low level for continuous operation. Compared to the best alkaline-water electrolysis reported in literature, the electrical-energy consumption could be 40 % lower with lignin electrolysis. At the anode, the Kraft lignin (KL) was oxidized to aromatic chemicals by POM or FeCl 3 , and reduced POM or Fe ions were regenerated during the electrolysis. Structure analysis of the residual KL indicated a reduction of the amount of hydroxyl groups and the cleavage of ether bonds. The results suggest that POM- or FeCl 3 -mediated electrolysis can significantly reduce the electrolysis energy consumption in hydrogen production and, simultaneously, depolymerize lignin to low-molecular-weight value-added aromatic chemicals. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

An analysis of degradation phenomena in polymer electrolyte membrane water electrolysis

NASA Astrophysics Data System (ADS)

Rakousky, Christoph; Reimer, Uwe; Wippermann, Klaus; Carmo, Marcelo; Lueke, Wiebke; Stolten, Detlef

2016-09-01

The durability of a polymer electrolyte membrane (PEM) water electrolysis single cell, assembled with regular porous transport layers (PTLs) is investigated for just over 1000 h. We observe a significant degradation rate of 194 μV h-1 and conclude that 78% of the detectable degradation can be explained by an increase in ohmic resistance, arising from the anodic Ti-PTL. Analysis of the polarization curves also indicates a decrease in the anodic exchange current density, j0, that results from the over-time contamination of the anode with Ti species. Furthermore, the average Pt-cathode particle size increases during the test, but we do not believe this phenomenon makes a significant contribution to increased cell voltages. To validate the anode Ti-PTL as a crucial source of increasing resistance, a second cell is assembled using Pt-coated Ti-PTLs. This yields a substantially reduced degradation rate of only 12 μV h-1, indicating that a non-corroding anode PTL is vital for PEM electrolyzers. It is our hope that forthcoming tailored PTLs will not only contribute to fast progress on cost-efficient stacks, but also to its long-term application of PEM electrolyzers involved in industrial processes.

Glass cylindrical filter for electrolysis cell

NASA Astrophysics Data System (ADS)

Abe, Shinichi; Akiyama, Fuminori

1992-09-01

Some electrolysis requires separation of electrolytic solution by a filter between two electrodes in order to prevent products from reacting secondarily at another electrode. These filters are usually made of a glass filter or ion exchanger membrane, and they are fixed at the electrolysis cell or cover one electrode. This report presents a detachable glass cylindrical filter for electrolytic reaction. The glass cylindrical filter was made from glass filter powder placed in a mold and heated at 800 C for 18 minutes. Using this filter, electrolytic reduction of carbon dioxide was performed in 0 C hot water with benzoin. This reaction produces aqueous oil from carbon dioxide and water. The products were compared with and without the filter and, although the yield did not differ between the two reaction systems, products without the filter contained highly polymerized oil compared to those with the filter. This suggests that the aqueous oil was produced at the cathode and polymerized at the anode.

Recent developments on ion-exchange membranes and electro-membrane processes.

PubMed

Nagarale, R K; Gohil, G S; Shahi, Vinod K

2006-02-28

Rapid growth of chemical and biotechnology in diversified areas fuels the demand for the need of reliable green technologies for the down stream processes, which include separation, purification and isolation of the molecules. Ion-exchange membrane technologies are non-hazardous in nature and being widely used not only for separation and purification but their application also extended towards energy conversion devices, storage batteries and sensors etc. Now there is a quite demand for the ion-exchange membrane with better selectivities, less electrical resistance, high chemical, mechanical and thermal stability as well as good durability. A lot of work has been done for the development of these types of ion-exchange membranes during the past twenty-five years. Herein we have reviewed the preparation of various types of ion-exchange membranes, their characterization and applications for different electro-membrane processes. Primary attention has been given to the chemical route used for the membrane preparation. Several general reactions used for the preparation of ion-exchange membranes were described. Methodologies used for the characterization of these membranes and their applications were also reviewed for the benefit of readers, so that they can get all information about the ion-exchange membranes at one platform. Although there are large number of reports available regarding preparations and applications of ion-exchange membranes more emphasis were predicted for the usefulness of these membranes or processes for solving certain type of industrial or social problems. More efforts are needed to bring many products or processes to pilot scale and extent their applications.

First report of vertically aligned (Sn,Ir)O2:F solid solution nanotubes: Highly efficient and robust oxygen evolution electrocatalysts for proton exchange membrane based water electrolysis

NASA Astrophysics Data System (ADS)

Ghadge, Shrinath Dattatray; Patel, Prasad P.; Datta, Moni K.; Velikokhatnyi, Oleg I.; Shanthi, Pavithra M.; Kumta, Prashant N.

2018-07-01

One dimensional (1D) vertically aligned nanotubes (VANTs) of (Sn0.8Ir0.2)O2:10F are synthesized for the first time by a sacrificial template assisted approach. The aim is to enhance the electrocatalytic activity of F doped (Sn,Ir)O2 solid solution electrocatalyst for oxygen evolution reaction (OER) in proton exchange membrane (PEM) based water electrolysis by generating (Sn0.8Ir0.2)O2:10F nanotubes (NTs). The 1D vertical channels and the high electrochemically active surface area (ECSA ∼38.46 m2g-1) provide for facile electron transport. This results in low surface charge transfer resistance (4.2 Ω cm2), low Tafel slope (58.8 mV dec-1) and excellent electrochemical OER performance with ∼2.3 and ∼2.6 fold higher electrocatalytic activity than 2D thin films of (Sn0.8Ir0.2)O2:10F and benchmark IrO2 electrocatalysts, respectively. Furthermore, (Sn0.8Ir0.2)O2:10F NTs exhibit excellent mass activity (21.67 A g-1), specific activity (0.0056 mAcm-2) and TOF (0.016 s-1), which is ∼2-2.6 fold higher than thin film electrocatalysts at an overpotential of 270 mV, with a total mass loading of 0.3 mg cm-2. In addition, (Sn0.8Ir0.2)O2:10F NTs demonstrate remarkable electrochemical durability - comparable to thin films of (Sn0.8Ir0.2)O2:10F and pure IrO2, operated under identical testing conditions in PEM water electrolysis. These results therefore indicate promise of (Sn0.8Ir0.2)O2:10F NTs as OER electrocatalysts for efficient and sustainable hydrogen production.

Mechanical characterization and durability of sintered porous transport layers for polymer electrolyte membrane electrolysis

NASA Astrophysics Data System (ADS)

Borgardt, Elena; Panchenko, Olha; Hackemüller, Franz Josef; Giffin, Jürgen; Bram, Martin; Müller, Martin; Lehnert, Werner; Stolten, Detlef

2018-01-01

Differential pressure electrolysis offers the potential for more efficient hydrogen compression. Due to the differential pressures acting within the electrolytic cell, the porous transport layer (PTL) is subjected to high stress. For safety reasons, the PTL's mechanical stability must be ensured. However, the requirements for high porosity and low thickness stand in contrast to that for mechanical stability. Porous transport layers for polymer electrolyte membrane (PEM) electrolysis are typically prepared by means of the thermal sintering of titanium powder. Thus far, the factors that influence the mechanical strength of the sintered bodies and how all requirements can be simultaneously fulfilled have not been investigated. Here, the static and dynamic mechanical properties of thin sintered titanium sheets are investigated ex-situ via tensile tests and periodic loading in a test cell, respectively. In order for a sintered PTL with a thickness of 500 μm and porosities above 25% to be able to withstand 50 bar differential pressure in the cell, the maximum flow field width should be limited to 3 mm. Thus, a method was developed to test the suitability of PTL materials for use in electrolysis for various differential pressures and flow field widths.

The Role of Ion Exchange Membranes in Membrane Capacitive Deionisation.

PubMed

Hassanvand, Armineh; Wei, Kajia; Talebi, Sahar; Chen, George Q; Kentish, Sandra E

2017-09-14

Ion-exchange membranes (IEMs) are unique in combining the electrochemical properties of ion exchange resins and the permeability of a membrane. They are being used widely to treat industrial effluents, and in seawater and brackish water desalination. Membrane Capacitive Deionisation (MCDI) is an emerging, energy efficient technology for brackish water desalination in which these ion-exchange membranes act as selective gates allowing the transport of counter-ions toward carbon electrodes. This article provides a summary of recent developments in the preparation, characterization, and performance of ion exchange membranes in the MCDI field. In some parts of this review, the most relevant literature in the area of electrodialysis (ED) is also discussed to better elucidate the role of the ion exchange membranes. We conclude that more work is required to better define the desalination performance of the proposed novel materials and cell designs for MCDI in treating a wide range of feed waters. The extent of fouling, the development of cleaning strategies, and further techno-economic studies, will add value to this emerging technique.

The Role of Ion Exchange Membranes in Membrane Capacitive Deionisation

PubMed Central

Hassanvand, Armineh; Wei, Kajia; Talebi, Sahar

2017-01-01

Ion-exchange membranes (IEMs) are unique in combining the electrochemical properties of ion exchange resins and the permeability of a membrane. They are being used widely to treat industrial effluents, and in seawater and brackish water desalination. Membrane Capacitive Deionisation (MCDI) is an emerging, energy efficient technology for brackish water desalination in which these ion-exchange membranes act as selective gates allowing the transport of counter-ions toward carbon electrodes. This article provides a summary of recent developments in the preparation, characterization, and performance of ion exchange membranes in the MCDI field. In some parts of this review, the most relevant literature in the area of electrodialysis (ED) is also discussed to better elucidate the role of the ion exchange membranes. We conclude that more work is required to better define the desalination performance of the proposed novel materials and cell designs for MCDI in treating a wide range of feed waters. The extent of fouling, the development of cleaning strategies, and further techno-economic studies, will add value to this emerging technique. PMID:28906442

Water Electrolysis for In-Situ Resource Utilization (ISRU)

NASA Technical Reports Server (NTRS)

Lee, Kristopher A.

2016-01-01

Sending humans to Mars for any significant amount of time will require capabilities and technologies that enable Earth independence. To move towards this independence, the resources found on Mars must be utilized to produce the items needed to sustain humans away from Earth. To accomplish this task, NASA is studying In Situ Resource Utilization (ISRU) systems and techniques to make use of the atmospheric carbon dioxide and the water found on Mars. Among other things, these substances can be harvested and processed to make oxygen and methane. Oxygen is essential, not only for sustaining the lives of the crew on Mars, but also as the oxidizer for an oxygen-methane propulsion system that could be utilized on a Mars ascent vehicle. Given the presence of water on Mars, the electrolysis of water is a common technique to produce the desired oxygen. Towards this goal, NASA designed and developed a Proton Exchange Membrane (PEM) water electrolysis system, which was originally slated to produce oxygen for propulsion and fuel cell use in the Mars Atmosphere and Regolith COllector/PrOcessor for Lander Operations (MARCO POLO) project. As part of the Human Exploration Spacecraft Testbed for Integration and Advancement (HESTIA) project, this same electrolysis system, originally targeted at enabling in situ propulsion and power, operated in a life-support scenario. During HESTIA testing at Johnson Space Center, the electrolysis system supplied oxygen to a chamber simulating a habitat housing four crewmembers. Inside the chamber, oxygen was removed from the atmosphere to simulate consumption by the crew, and the electrolysis system's oxygen was added to replenish it. The electrolysis system operated nominally throughout the duration of the HESTIA test campaign, and the oxygen levels in the life support chamber were maintained at the desired levels.

Water permeation through anion exchange membranes

NASA Astrophysics Data System (ADS)

Luo, Xiaoyan; Wright, Andrew; Weissbach, Thomas; Holdcroft, Steven

2018-01-01

An understanding of water permeation through solid polymer electrolyte (SPE) membranes is crucial to offset the unbalanced water activity within SPE fuel cells. We examine water permeation through an emerging class of anion exchange membranes, hexamethyl-p-terphenyl poly (dimethylbenzimidazolium) (HMT-PMBI), and compare it against series of membrane thickness for a commercial anion exchange membrane (AEM), Fumapem® FAA-3, and a series of proton exchange membranes, Nafion®. The HMT-PMBI membrane is found to possess higher water permeabilities than Fumapem® FAA-3 and comparable permeability than Nafion (H+). By measuring water permeation through membranes of different thicknesses, we are able to decouple, for the first time, internal and interfacial water permeation resistances through anion exchange membranes. Permeation resistances on liquid/membrane interface is found to be negligible compared to that for vapor/membrane for both series of AEMs. Correspondingly, the resistance of liquid water permeation is found to be one order of magnitude smaller compared to that of vapor water permeation. HMT-PMBI possesses larger effective internal water permeation coefficient than both Fumapem® FAA-3 and Nafion® membranes (60 and 18% larger, respectively). In contrast, the effective interfacial permeation coefficient of HMT-PMBI is found to be similar to Fumapem® (±5%) but smaller than Nafion®(H+) (by 14%).

Liquid membrane coated ion-exchange column solids

DOEpatents

Barkey, Dale P.

1988-01-01

This invention relates to a method for improving the performance of liquid membrane separations by coating a liquid membrane onto solid ion-exchange resin beads in a fixed bed. Ion-exchange beads fabricated from an ion-exchange resin are swelled with water and are coated with a liquid membrane material that forms a film over the beads. The beads constitute a fixed bed ion-exchange column. Fluid being treated that contains the desired ion to be trapped by the ion-exchange particle is passed through the column. A carrier molecule, contained in the liquid membrane ion-exchange material, is selective for the desired ion in the fluid. The carrier molecule forms a complex with the desired ion, transporting it through the membrane and thus separating it from the other ions. The solution is fed continuously until breakthrough occurs at which time the ion is recovered, and the bed is regenerated.

An Environmentally Friendly Process Involving Refining and Membrane-Based Electrolysis for Magnesium Recovery from Partially Oxidized Scrap Alloy

NASA Astrophysics Data System (ADS)

Guan, Xiaofei; Pal, Uday B.; Powell, Adam C.

2013-10-01

Magnesium is recovered from partially oxidized scrap alloy by combining refining and solid oxide membrane (SOM) electrolysis. In this combined process, a molten salt eutectic flux (45 wt.% MgF2-55 wt.% CaF2) containing 10 wt.% MgO and 2 wt.% YF3 was used as the medium for magnesium recovery. During refining, magnesium and its oxide are dissolved from the scrap into the molten flux. Forming gas is bubbled through the flux and the dissolved magnesium is removed via the gas phase and condensed in a separate condenser at a lower temperature. The molten flux has a finite solubility for magnesium and acts as a selective medium for magnesium dissolution, but not aluminum or iron, and therefore the magnesium recovered has high purity. After refining, SOM electrolysis is performed in the same reactor to enable electrolysis of the dissolved magnesium oxide in the molten flux producing magnesium at the cathode and oxygen at the SOM anode. During SOM electrolysis, it is necessary to decrease the concentration of the dissolved magnesium in the flux to improve the faradaic current efficiency and prevent degradation of the SOM. Thus, for both refining and SOM electrolysis, it is very important to measure and control the magnesium solubility in the molten flux. High magnesium solubility facilitates refining whereas lower solubility benefits the SOM electrolysis process. Computational fluid dynamics modeling was employed to simulate the flow behavior of the flux stirred by the forming gas. Based on the modeling results, an optimized design of the stirring tubes and its placement in the flux are determined for efficiently removing the dissolved magnesium and also increasing the efficiency of the SOM electrolysis process.

The role of ion-exchange membrane in energy conversion

NASA Astrophysics Data System (ADS)

Khoiruddin, Aryanti, Putu T. P.; Hakim, Ahmad N.; Wenten, I. Gede

2017-05-01

Ion-exchange membrane (IEM) may play an important role in the future of electrical energy generation which is considered as renewable and clean energy. Fell cell (FC) is one of the promising technologies for solving energy issues in the future owing to the interesting features such as high electrical efficiency, low emissions, low noise level, and modularity. IEM-based processes, such as microbial fuel cell (MFC) and reverse electrodialysis (RED) may be combined with water or wastewater treatment into an integrated system. By using the integrated system, water and energy could be produced simultaneously. The IEM-based processes can be used for direct electricity generation or long term energy storage such as by harnessing surplus electricity from an existing renewable energy system to be converted into hydrogen gas via electrolysis or stored into chemical energy via redox flow battery (RFB). In this paper, recent development and applications of IEM-based processes in energy conversion are reviewed. In addition, perspective and challenges of IEM-based processes in energy conversion are pointed out.

Liquid membrane coated ion-exchange column solids

DOEpatents

Barkey, Dale P.

1989-01-01

This invention relates to a method for improving the performance of liquid embrane separations by coating a liquid membrane onto solid ion-exchange resin beads in a fixed bed. Ion-exchange beads fabricated from an ion-exchange resin are swelled with water and are coated with a liquid membrane material that forms a film over the beads. The beads constitute a fixed bed ion-exchange column. Fluid being treated that contains the desired ion to be trapped by the ion-exchange particle is passed through the column. A carrier molecule, contained in the liquid membrane ion-exchange material, is selected for the desired ion in the fluid. The carrier molecule forms a complex with the desired ion, transporting it through the membrane and thus separating it from the other ions. The solution is fed continuously until breakthrough occurs at which time the ion is recovered, and the bed is regenerated.

Feasibility study of NaOH regeneration in acid gas removal unit using membrane electrolysis

NASA Astrophysics Data System (ADS)

Taufany, Fadlilatul; Pratama, Alvian; Romzuddin, Muhammad

2017-05-01

The world's energy demand is increasing with the development of human civilization. Due to limited energy resource, after 2020 fossil fuels thus is predicted will be replaced by renewable resources. Taking an example, one of the potential renewable energy to be considered is biogas, as its high content of methane, which can be produced via the fermentation process of the organic compounds under controlled anaerobic environment by utilizing the methanogen bacteria. However, prior the further use, this biogas must be purified from its impurities contents, i.e. acid gas of CO2 and H2S, up to 4% and 16 ppmv, respectively, in the acid gas removal unit. This such of purification efforts, will significantly increase the higher heating value of biogas, approximately from 600 to 900 Btu/Scf. During the purification process in this acid gas removal unit, NaOH solution is used as a liquid absorbent to reduce those acid gases content, in which the by-product of alkali salt (brine) was produced as waste. Here we report the feasibility study of the NaOH regeneration process in acid gas removal unit via membrane electrolysis technology, in which both the technical and economic aspects are taken account. To be precise in procedure, the anode semi-cell was filled with the brine solution, while the cathode semi-cell was filled with demineralized water, and those electrodes were separated by the cation exchange membrane. Furthermore, the applied potential was varied ranging from 5, 10, 15 and to 20 V, while the concentration of KCl electrolyte solutions were varied ranging from 0.01, 0.05, 0.1, and to 0.03 M. This study was conducted under controlled temperatures of 30 and 50 °C. Here we found that the % sodium recovery was increased along with the applied potential, temperature, and the decrease in KCl electrolyte concentration. We found that the best results, by means of the highest % sodium recovery, i.e. 97.26 %, was achieved under the experimental condition of temperature at 30

Multi-Physics Modeling of Molten Salt Transport in Solid Oxide Membrane (SOM) Electrolysis and Recycling of Magnesium

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

Powell, Adam; Pati, Soobhankar

2012-03-11

Solid Oxide Membrane (SOM) Electrolysis is a new energy-efficient zero-emissions process for producing high-purity magnesium and high-purity oxygen directly from industrial-grade MgO. SOM Recycling combines SOM electrolysis with electrorefining, continuously and efficiently producing high-purity magnesium from low-purity partially oxidized scrap. In both processes, electrolysis and/or electrorefining take place in the crucible, where raw material is continuously fed into the molten salt electrolyte, producing magnesium vapor at the cathode and oxygen at the inert anode inside the SOM. This paper describes a three-dimensional multi-physics finite-element model of ionic current, fluid flow driven by argon bubbling and thermal buoyancy, and heat andmore » mass transport in the crucible. The model predicts the effects of stirring on the anode boundary layer and its time scale of formation, and the effect of natural convection at the outer wall. MOxST has developed this model as a tool for scale-up design of these closely-related processes.« less

Improved water electrolysis using magnetic heating of FeC-Ni core-shell nanoparticles

NASA Astrophysics Data System (ADS)

Niether, Christiane; Faure, Stéphane; Bordet, Alexis; Deseure, Jonathan; Chatenet, Marian; Carrey, Julian; Chaudret, Bruno; Rouet, Alain

2018-06-01

Water electrolysis enables the storage of renewable electricity via the chemical bonds of hydrogen. However, proton-exchange-membrane electrolysers are impeded by the high cost and low availability of their noble-metal electrocatalysts, whereas alkaline electrolysers operate at a low power density. Here, we demonstrate that electrocatalytic reactions relevant for water splitting can be improved by employing magnetic heating of noble-metal-free catalysts. Using nickel-coated iron carbide nanoparticles, which are prone to magnetic heating under high-frequency alternating magnetic fields, the overpotential (at 20 mA cm-2) required for oxygen evolution in an alkaline water-electrolysis flow-cell was decreased by 200 mV and that for hydrogen evolution was decreased by 100 mV. This enhancement of oxygen-evolution kinetics is equivalent to a rise of the cell temperature to 200 °C, but in practice it increased by 5 °C only. This work suggests that, in the future, water splitting near the equilibrium voltage could be possible at room temperature, which is currently beyond reach in the classic approach to water electrolysis.

Low-Cost and Durable Bipolar Plates for Proton Exchange Membrane Electrolyzers

NASA Astrophysics Data System (ADS)

Lettenmeier, P.; Wang, R.; Abouatallah, R.; Saruhan, B.; Freitag, O.; Gazdzicki, P.; Morawietz, T.; Hiesgen, R.; Gago, A. S.; Friedrich, K. A.

2017-03-01

Cost reduction and high efficiency are the mayor challenges for sustainable H2 production via proton exchange membrane (PEM) electrolysis. Titanium-based components such as bipolar plates (BPP) have the largest contribution to the capital cost. This work proposes the use of stainless steel BPPs coated with Nb and Ti by magnetron sputtering physical vapor deposition (PVD) and vacuum plasma spraying (VPS), respectively. The physical properties of the coatings are thoroughly characterized by scanning electron, atomic force microscopies (SEM, AFM); and X-ray diffraction, photoelectron spectroscopies (XRD, XPS). The Ti coating (50 μm) protects the stainless steel substrate against corrosion, while a 50-fold thinner layer of Nb decreases the contact resistance by almost one order of magnitude. The Nb/Ti-coated stainless steel bipolar BPPs endure the harsh environment of the anode for more than 1000 h of operation under nominal conditions, showing a potential use in PEM electrolyzers for large-scale H2 production from renewables.

Low-Cost and Durable Bipolar Plates for Proton Exchange Membrane Electrolyzers

PubMed Central

Lettenmeier, P.; Wang, R.; Abouatallah, R.; Saruhan, B.; Freitag, O.; Gazdzicki, P.; Morawietz, T.; Hiesgen, R.; Gago, A. S.; Friedrich, K. A.

2017-01-01

Cost reduction and high efficiency are the mayor challenges for sustainable H2 production via proton exchange membrane (PEM) electrolysis. Titanium-based components such as bipolar plates (BPP) have the largest contribution to the capital cost. This work proposes the use of stainless steel BPPs coated with Nb and Ti by magnetron sputtering physical vapor deposition (PVD) and vacuum plasma spraying (VPS), respectively. The physical properties of the coatings are thoroughly characterized by scanning electron, atomic force microscopies (SEM, AFM); and X-ray diffraction, photoelectron spectroscopies (XRD, XPS). The Ti coating (50 μm) protects the stainless steel substrate against corrosion, while a 50-fold thinner layer of Nb decreases the contact resistance by almost one order of magnitude. The Nb/Ti-coated stainless steel bipolar BPPs endure the harsh environment of the anode for more than 1000 h of operation under nominal conditions, showing a potential use in PEM electrolyzers for large-scale H2 production from renewables. PMID:28294119

Electrolysis cell stimulation

NASA Technical Reports Server (NTRS)

Gordon, L. H.; Phillips, B. R.; Evangelista, J.

1978-01-01

Computer program represents attempt to understand and model characteristics of electrolysis cells. It allows user to determine how cell efficiency is affected by temperature, pressure, current density, electrolyte concentration, characteristic dimensions, membrane resistance, and electrolyte circulation rate. It also calculates ratio of bubble velocity to electrolyte velocity for anode and cathode chambers.

Synthesis and Characterization of Perfluoro Quaternary Ammonium Anion Exchange Membranes

DTIC Science & Technology

2012-01-01

study, new alkaline exchange membranes were prepared from the perfluorinated 3M ionomer with various quaternary ammonium cations attached with...ammonium anion exchange membranes Report Title ABSTRACT In this study, new alkaline exchange membranes were prepared from the perfluorinated 3M ionomer...exchange membranes were prepared from the perfluorinated 3M ionomer with vari- ous quaternary ammonium cations attached with sulfonamide linkage. The

Membrane microfilter device for selective capture, electrolysis and genomic analysis of human circulating tumor cells.

PubMed

Zheng, Siyang; Lin, Henry; Liu, Jing-Quan; Balic, Marija; Datar, Ram; Cote, Richard J; Tai, Yu-Chong

2007-08-31

This paper presents development of a parylene membrane microfilter device for single stage capture and electrolysis of circulating tumor cells (CTCs) in human blood, and the potential of this device to allow genomic analysis. The presence and number of CTCs in blood has recently been demonstrated to provide significant prognostic information for patients with metastatic breast cancer. While finding as few as five CTCs in about 7.5mL of blood (i.e., 10(10) blood cells in) is clinically significant, detection of CTCs is currently difficult and time consuming. CTC enrichment is performed by either gradient centrifugation of CTC based on their buoyant density or magnetic separation of epithelial CTC, both of which are laborious procedures with variable efficiency, and CTC identification is typically done by trained pathologists through visual observation of stained cytokeratin-positive epithelial CTC. These processes may take hours, if not days. Work presented here provides a micro-electro-mechanical system (MEMS)-based option to make this process simpler, faster, better and cheaper. We exploited the size difference between CTCs and human blood cells to achieve the CTC capture on filter with approximately 90% recovery within 10 min, which is superior to current approaches. Following capture, we facilitated polymerase chain reaction (PCR)-based genomic analysis by performing on-membrane electrolysis with embedded electrodes reaching each of the individual 16,000 filtering pores. The biggest advantage for this on-membrane in situ cell lysis is the high efficiency since cells are immobilized, allowing their direct contact with electrodes. As a proof-of-principle, we show beta actin gene PCR, the same technology can be easily extended to real time PCR for CTC-specific transcript to allow molecular identification of CTC and their further characterization.

Scaling-Up Solid Oxide Membrane Electrolysis Technology for Magnesium Production

NASA Astrophysics Data System (ADS)

Pati, Soobhankar; Powell, Adam; Tucker, Steve; Derezinski, Steve

Metal Oxygen Separation Technologies, Inc. (MOxST) is actively developing Solid Oxide Membrane (SOM) electrolysis technology for production of magnesium directly from its oxide. The vital component of this technology is the oxygen ion-conducting solid zirconia electrolyte separating the molten flux (a mixture of salts and oxide) and the inert anode. The zirconia not only protects the anode from the flux but also prevents anode gas back-reaction, increasing the efficiency. This makes it possible to produce low-cost high-purity magnesium and high-purity oxygen as a byproduct with no direct greenhouse gas emissions. In this paper we discuss the design modifications made to address the scaling-up challenges, particularly for producing magnesium in liquid form. The key accomplishment to date is the successful development of a prototype capable of producing few kilograms of magnesium per day. We will also describe the prerequisite properties of an inert anode and suitable materials for the same.

Lifetime of Sodium Beta-Alumina Membranes in Molten Sodium Hydroxide

DTIC Science & Technology

2008-07-01

ABSTRACT Summary: Sodium metal can be made by electrolysis of molten sodium hydroxide in sodium beta-alumina membrane electrolysis cells... electrolysis of molten sodium hydroxide in sodium ”-alumina membrane electrolysis cells. However, there are some uncertainties about the lifetime of the...the properties of the membrane degrade upon long term contact with molten sodium hydroxide. Electrolysis cells were designed, but it proved

Production of an ion-exchange membrane-catalytic electrode bonded material for electrolytic cells

NASA Technical Reports Server (NTRS)

Takenaka, H.; Torikai, E.

1986-01-01

A good bond is achieved by placing a metal salt in solution on one side of a membrane and a reducing agent on the other side so that the reducing agent penetrates the membrane and reduces the metal. Thus, a solution containing Pt, Rh, etc., is placed on one side of the membrane and a reducing agent such as NaBH, is placed on the other side. The bonded metal layer obtained is superior in catalytic activity and is suitable as an electrode in a cell such as for solid polymer electrolyte water electrolysis.

Na+/H+ exchange activity in the plasma membrane of Arabidopsis.

PubMed

Qiu, Quan-Sheng; Barkla, Bronwyn J; Vera-Estrella, Rosario; Zhu, Jian-Kang; Schumaker, Karen S

2003-06-01

In plants, Na+/H+ exchangers in the plasma membrane are critical for growth in high levels of salt, removing toxic Na+ from the cytoplasm by transport out of the cell. The molecular identity of a plasma membrane Na+/H+ exchanger in Arabidopsis (SOS1) has recently been determined. In this study, immunological analysis provided evidence that SOS1 localizes to the plasma membrane of leaves and roots. To characterize the transport activity of this protein, purified plasma membrane vesicles were isolated from leaves of Arabidopsis. Na+/H+ exchange activity, monitored as the ability of Na to dissipate an established pH gradient, was absent in plants grown without salt. However, exchange activity was induced when plants were grown in 250 mm NaCl and increased with prolonged salt exposure up to 8 d. H+-coupled exchange was specific for Na, because chloride salts of other monovalent cations did not dissipate the pH gradient. Na+/H+ exchange activity was dependent on Na (substrate) concentration, and kinetic analysis indicated that the affinity (apparent Km) of the transporter for Na+ is 22.8 mm. Data from two experimental approaches supports electroneutral exchange (one Na+ exchanged for one proton): (a) no change in membrane potential was measured during the exchange reaction, and (b) Na+/H+ exchange was unaffected by the presence or absence of a membrane potential. Results from this research provide a framework for future studies into the regulation of the plant plasma membrane Na+/H+ exchanger and its relative contribution to the maintenance of cellular Na+ homeostasis during plant growth in salt.

Specific ion effects on membrane potential and the permselectivity of ion exchange membranes.

PubMed

Geise, Geoffrey M; Cassady, Harrison J; Paul, Donald R; Logan, Bruce E; Hickner, Michael A

2014-10-21

Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions. Our goal in this work was to better understand membrane behaviour in aqueous ammonium bicarbonate, which is of interest for closed-loop energy generation processes. Here we characterized the permselectivity of four commercial ion exchange membranes in aqueous solutions of sodium chloride, ammonium chloride, sodium bicarbonate, and ammonium bicarbonate. This stepwise approach, using four different ions in aqueous solution, was used to better understand how these specific ions affect ion transport in ion exchange membranes. Characterization of cation and anion exchange membrane permselectivity, using these ions, is discussed from the perspective of the difference in the physical chemistry of the hydrated ions, along with an accompanying re-derivation and examination of the basic equations that describe membrane potential. In general, permselectivity was highest in sodium chloride and lowest in ammonium bicarbonate solutions, and the nature of both the counter- and co-ions appeared to influence measured permselectivity. The counter-ion type influences the binding affinity between counter-ions and polymer fixed charge groups, and higher binding affinity between fixed charge sites and counter-ions within the membrane decreases the effective membrane charge density. As a result permselectivity decreases. The charge density and polarizability

Fundamental characteristics study of anion-exchange PVDF-SiO(2) membranes.

PubMed

Zuo, Xingtao; Shi, Wenxin; Yu, Shuili; He, Jiajie

2012-01-01

A new type of poly(vinylidene fluoride)(PVDF)-SiO(2) hybrid anion-exchange membrane was prepared by blending method. The anion-exchange groups were introduced by the reaction of epoxy groups with trimethylamine (TMA). Contact angle between water and the membrane surface was measured to characterize the hydrophilicity change of the membrane surface. The effects of nano-sized SiO(2) particles in the membrane-forming materials on the membrane mechanical properties and conductivity were also investigated. The experimental results indicated that PVDF-SiO(2) anion-exchange membranes exhibited better water content, ion-exchange capacity, conductivity and mechanic properties, and so may find potential applications in alkaline membrane fuel cells and water treatment processes.

Game Changing Development Program - Next Generation Life Support Project: Oxygen Recovery From Carbon Dioxide Using Ion Exchange Membrane Electrolysis Technology

NASA Technical Reports Server (NTRS)

Burke, Kenneth A.; Jiao, Feng

2016-01-01

This report summarizes the Phase I research and development work performed during the March 13, 2015 to July 13, 2016 period. The proposal for this work was submitted in response to NASA Research Announcement NNH14ZOA001N, "Space Technology Research, Development, Demonstration, and Infusion 2014 (SpaceTech-REDDI-2014)," Appendix 14GCD-C2 "Game Changing Development Program, Advanced Oxygen Recovery for Spacecraft Life Support Systems Appendix" The Task Agreement for this Phase I work is Document Control Number: GCDP-02-TA-15015. The objective of the Phase I project was to demonstrate in laboratories two Engineering Development Units (EDU) that perform critical functions of the low temperature carbon dioxide electrolysis and the catalytic conversion of carbon monoxide into carbon and carbon dioxide. The low temperature carbon dioxide electrolysis EDU was built by the University of Delaware with Dr. Feng Jiao as the principal investigator in charge of this EDU development (under NASA Contract NNC15CA04C). The carbon monoxide catalytic conversion EDU was built by the NASA Glenn Research Center with Kenneth Burke as the principal investigator and overall project leader for the development of both EDUs. Both EDUs were successfully developed and demonstrated the critical functions for each process. The carbon dioxide electrolysis EDU was delivered to the NASA Johnson Space Center and the carbon monoxide catalytic conversion EDU was delivered to the NASA Marshall Spaceflight Center.

Proton exchange membranes prepared by grafting of styrene/divinylbenzene into crosslinked PTFE membranes

NASA Astrophysics Data System (ADS)

Li, Jingye; Ichizuri, Shogo; Asano, Saneto; Mutou, Fumihiro; Ikeda, Shigetoshi; Iida, Minoru; Miura, Takaharu; Oshima, Akihiro; Tabata, Yoneho; Washio, Masakazu

2005-07-01

Thin PTFE membranes were prepared by coating the PTFE dispersion onto the aluminum films. Thus the thin crosslinked PTFE (RX-PTFE) membranes were obtained by means of electron beam irradiation above the melting temperature of PTFE under oxygen-free atmosphere. The RX-PTFE membranes were pre-irradiated and grafted by styrene with or without divinylbenzene (DVB) in liquid phase. The existence of DVB accelerated the initial grafting rate. The styrene grafted RX-PTFE membranes are white colored, on the other hand, the styrene/DVB grafted RX-PTFE membranes are colorless. The proton exchange membranes (PEMs) were obtained by sulfonating the grafted membranes using chlorosulfonic acid. The ion exchange capacity (IEC) values of the PEMs ranging from 1.5 to 2.8 meq/g were obtained. The PEMs made from the styrene/DVB grafted membranes showed higher chemical stability than those of the styrene grafted membranes under oxidative circumstance.

Epoxy-crosslinked sulfonated poly (phenylene) copolymer proton exchange membranes

DOEpatents

Hibbs, Michael; Fujimoto, Cy H.; Norman, Kirsten; Hickner, Michael A.

2010-10-19

An epoxy-crosslinked sulfonated poly(phenylene) copolymer composition used as proton exchange membranes, methods of making the same, and their use as proton exchange membranes (PEM) in hydrogen fuel cells, direct methanol fuel cell, in electrode casting solutions and electrodes, and in sulfur dioxide electrolyzers. These improved membranes are tougher, have higher temperature capability, and lower SO.sub.2 crossover rates.

Na+/H+ Exchange Activity in the Plasma Membrane of Arabidopsis1

PubMed Central

Qiu, Quan-Sheng; Barkla, Bronwyn J.; Vera-Estrella, Rosario; Zhu, Jian-Kang; Schumaker, Karen S.

2003-01-01

In plants, Na+/H+ exchangers in the plasma membrane are critical for growth in high levels of salt, removing toxic Na+ from the cytoplasm by transport out of the cell. The molecular identity of a plasma membrane Na+/H+ exchanger in Arabidopsis (SOS1) has recently been determined. In this study, immunological analysis provided evidence that SOS1 localizes to the plasma membrane of leaves and roots. To characterize the transport activity of this protein, purified plasma membrane vesicles were isolated from leaves of Arabidopsis. Na+/H+ exchange activity, monitored as the ability of Na to dissipate an established pH gradient, was absent in plants grown without salt. However, exchange activity was induced when plants were grown in 250 mm NaCl and increased with prolonged salt exposure up to 8 d. H+-coupled exchange was specific for Na, because chloride salts of other monovalent cations did not dissipate the pH gradient. Na+/H+ exchange activity was dependent on Na (substrate) concentration, and kinetic analysis indicated that the affinity (apparent Km) of the transporter for Na+ is 22.8 mm. Data from two experimental approaches supports electroneutral exchange (one Na+ exchanged for one proton): (a) no change in membrane potential was measured during the exchange reaction, and (b) Na+/H+ exchange was unaffected by the presence or absence of a membrane potential. Results from this research provide a framework for future studies into the regulation of the plant plasma membrane Na+/H+ exchanger and its relative contribution to the maintenance of cellular Na+ homeostasis during plant growth in salt. PMID:12805632

Optomechanical characterization of proton-exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Jalani, Nikhil H.; Mizar, Shivananda P.; Choi, Pyoungho; Furlong, Cosme; Datta, Ravindra

2004-08-01

Nafion is widely used as the polymer electrolyte in proton exchange membrane (PEM) fuel cells. The properties that make the Nafion membrane indispensable are the combination of good water uptake, ion-exchange capacity, proton conductivity, gas permeability, and excellent electrochemical stability. The amount of water sorbed in the Nafion membrane is critical as the proton conductivity depends directly on the water content of the membrane which determines the fuel cell performance. The factors which affect the extent of the solvent uptake by Nafion are temperature, ion-exchange capacity, pretreatment of membrane, and the physical state of absorbing water, whether it is in liquid or vapor phase. The water sorption in the membrane is explained in terms of thermodynamic equilibrium of water in the vapor and absorption phases. As the membrane imbibes more water, the membrane matrix expands and exerts a pressure on the pore liquid which affects its chemical potential and limits extent of swelling. The extent of matrix expansion of the membranes depends on the elastic modulus, E, of the membrane, which directly affects the sorption. Hence, it is important to understand the variation of E for Nafion membrane with relative humidity (RH) and temperature. Optoelectronic holography (OEH) techniques are applied to perform quantitative, noninvasive, full field of view investigations to determine temperature and water activity dependence of E. The results obtained confirm that with the increase in temperature, E decreases and the membranes imbibes more water. Such results will allow optimization and realization of fuel cells with improved efficiency and performance.

Carbonate and Bicarbonate Ion Transport in Alkaline Anion Exchange Membranes

DTIC Science & Technology

2013-06-25

membranes (AEMs) are being developed for potential use in fuel cell systems which include portable power applications. In a fuel cell , these membranes...Alkaline Anion Exchange Membranes Report Title ABSTRACT Anion exchange membranes (AEMs) are being developed for potential use in fuel cell systems which...include portable power applications. In a fuel cell , these membranes transport hydroxide ions from the cathode to the anode. If carbon dioxide is

Anion selective membrane. [ion exchange resins and ion exchange membrane electrolytes for electrolytic cells

NASA Technical Reports Server (NTRS)

Alexander, S. S.; Geoffroy, R. R.; Hodgdon, R. B.

1975-01-01

Experimental anion permselective membranes were prepared and tested for their suitability as cell separators in a chemical redox power storage system being developed at NASA-Lewis Research Center. The goals of long-term (1000 hr) oxidative and thermal stability at 80 C in FeCl3 and CrCl3 electrolytes were met by most of the weak base and strong base amino exchange groups considered in the program. Good stability is exhibited by several of the membrane substrate resins. These are 'styrene' divinylbenzene copolymer and PVC film. At least four membrane systems produce strong flexible films with electrochemical properties (resistivity, cation transfer) superior to those of the 103QZL, the most promising commercial membrane. The physical and chemical properties of the resins are listed.

Efficient treatment of aniline containing wastewater in bipolar membrane microbial electrolysis cell-Fenton system.

PubMed

Li, Xiaohu; Jin, Xiangdan; Zhao, Nannan; Angelidaki, Irini; Zhang, Yifeng

2017-08-01

Aniline-containing wastewater can cause significant environmental problems and threaten the humans's life. However, rapid degradation of aniline with cost-efficient methods remains a challenge. In this work, a novel microbial electrolysis cell with bipolar membrane was integrated with Fenton reaction (MEC-Fenton) for efficient treatment of real wastewater containing a high concentration (4460 ± 52 mg L -1 ) of aniline. In this system, H 2 O 2 was in situ electro-synthesized from O 2 reduction on the graphite cathode and was simultaneously used as source of OH for the oxidation of aniline wastewater under an acidic condition maintained by the bipolar membrane. The aniline was effectively degraded following first-order kinetics at a rate constant of 0.0166 h -1 under an applied voltage of 0.5 V. Meanwhile, a total organic carbon (TOC) removal efficiency of 93.1 ± 1.2% was obtained, revealing efficient mineralization of aniline. The applicability of bipolar membrane MEC-Fenton system was successfully demonstrated with actual aniline wastewater. Moreover, energy balance showed that the system could be a promising technology for removal of biorefractory organic pollutants from wastewaters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Importance of balancing membrane and electrode water in anion exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Omasta, T. J.; Wang, L.; Peng, X.; Lewis, C. A.; Varcoe, J. R.; Mustain, W. E.

2018-01-01

Anion exchange membrane fuel cells (AEMFCs) offer several potential advantages over proton exchange membrane fuel cells (PEMFCs), most notably to overcome the cost barrier that has slowed the growth and large scale implementation of fuel cells for transportation. However, limitations in performance have held back AEMFCs, specifically in the areas of stability, carbonation, and maximum achievable current and power densities. In order for AEMFCs to contend with PEMFCs for market viability, it is necessary to realize a competitive cell performance. This work demonstrates a new benchmark for a H2/O2 AEMFC with a peak power density of 1.4 W cm-2 at 60 °C. This was accomplished by taking a more precise look at balancing necessary membrane hydration while preventing electrode flooding, which somewhat surprisingly can occur both at the anode and the cathode. Specifically, radiation-grafted ETFE-based anion exchange membranes and anion exchange ionomer powder, functionalized with benchmark benzyltrimethylammonium groups, were utilized to examine the effects of the following parameters on AEMFC performance: feed gas flow rate, the use of hydrophobic vs. hydrophilic gas diffusion layers, and gas feed dew points.

Improving electrokinetic microdevice stability by controlling electrolysis bubbles.

PubMed

Lee, Hwi Yong; Barber, Cedrick; Minerick, Adrienne R

2014-07-01

The voltage-operating window for many electrokinetic microdevices is limited by electrolysis gas bubbles that destabilize microfluidic system causing noise and irreproducible responses above ∼3 V DC and less than ∼1 kHz AC at 3 Vpp. Surfactant additives, SDS and Triton X-100, and an integrated semipermeable SnakeSkin® membrane were employed to control and assess electrolysis bubbles from platinum electrodes in a 180 by 70 μm, 10 mm long microchannel. Stabilized current responses at 100 V DC were observed with surfactant additives or SnakeSkin® barriers. Electrolysis bubble behaviors, visualized via video microscopy at the electrode surface and in the microchannels, were found to be influenced by surfactant function and SnakeSkin® barriers. Both SDS and Triton X-100 surfactants promoted smaller bubble diameters and faster bubble detachment from electrode surfaces via increasing gas solubility. In contrast, SnakeSkin® membranes enhanced natural convection and blocked bubbles from entering the microchannels and thus reduced current disturbances in the electric field. This data illustrated that electrode surface behaviors had substantially greater impacts on current stability than microbubbles within microchannels. Thus, physically blocking bubbles from microchannels is less effective than electrode functionalization approaches to stabilize electrokinetic microfluidic systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid capacitive deionization with anion-exchange membranes for lithium extraction

NASA Astrophysics Data System (ADS)

Siekierka, Anna; Bryjak, Marek

2017-11-01

Lithium is considered to be a critical material for various industrial fields. We present our studies on extraction lithium from diluted aqueous solution by novel hybrid system based on a membrane capacitive deionization and batteries desalination. Hybrid CDI is comprised by a lithium selective adsorbent, activated carbon electrode and anion-exchange membranes. Here, we demonstrated implication of various type of anion-exchange membranes and influence their properties on effective capacity and energy requirements in charge/discharge steps. We described a configuration with anion-exchange membrane characterized by adsorption capacity of 35 mg/g of Li+ with 0.08Wh/g and removal efficiency of 60 % of lithium ions, using novel selective desalination technique.

Interpenetrating polymer network ion exchange membranes and method for preparing same

DOEpatents

Alexandratos, Spiro D.; Danesi, Pier R.; Horwitz, E. Philip

1989-01-01

Interpenetrating polymer network ion exchange membranes include a microporous polymeric support film interpenetrated by an ion exchange polymer and are produced by absorbing and polymerizing monomers within the support film. The ion exchange polymer provides ion exchange ligands at the surface of and throughout the support film which have sufficient ligand mobility to extract and transport ions across the membrane.

Gas Transfer in Cellularized Collagen-Membrane Gas Exchange Devices.

PubMed

Lo, Justin H; Bassett, Erik K; Penson, Elliot J N; Hoganson, David M; Vacanti, Joseph P

2015-08-01

Chronic lower respiratory disease is highly prevalent in the United States, and there remains a need for alternatives to lung transplant for patients who progress to end-stage lung disease. Portable or implantable gas oxygenators based on microfluidic technologies can address this need, provided they operate both efficiently and biocompatibly. Incorporating biomimetic materials into such devices can help replicate native gas exchange function and additionally support cellular components. In this work, we have developed microfluidic devices that enable blood gas exchange across ultra-thin collagen membranes (as thin as 2 μm). Endothelial, stromal, and parenchymal cells readily adhere to these membranes, and long-term culture with cellular components results in remodeling, reflected by reduced membrane thickness. Functionally, acellular collagen-membrane lung devices can mediate effective gas exchange up to ∼288 mL/min/m(2) of oxygen and ∼685 mL/min/m(2) of carbon dioxide, approaching the gas exchange efficiency noted in the native lung. Testing several configurations of lung devices to explore various physical parameters of the device design, we concluded that thinner membranes and longer gas exchange distances result in improved hemoglobin saturation and increases in pO2. However, in the design space tested, these effects are relatively small compared to the improvement in overall oxygen and carbon dioxide transfer by increasing the blood flow rate. Finally, devices cultured with endothelial and parenchymal cells achieved similar gas exchange rates compared with acellular devices. Biomimetic blood oxygenator design opens the possibility of creating portable or implantable microfluidic devices that achieve efficient gas transfer while also maintaining physiologic conditions.

High performance robust F-doped tin oxide based oxygen evolution electro-catalysts for PEM based water electrolysis

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

Datta, Moni Kanchan; Kadakia, Karan; Velikokhatnyi, Oleg I

2013-01-01

Identification and development of non-noble metal based electro-catalysts or electro-catalysts comprising compositions with significantly reduced amounts of expensive noble metal contents (e.g. IrO{sub 2}, Pt) with comparable electrochemical performance to the standard noble metal/metal oxide for proton exchange membrane (PEM) based water electrolysis would signify a major breakthrough in hydrogen generation via water electrolysis. Development of such systems would lead to two primary outcomes: first, a reduction in the overall capital costs of PEM based water electrolyzers, and second, attainment of the targeted hydrogen production costs (<$3.00/gge delivered by 2015) comparable to conventional liquid fuels. In line with these goals,more » by exploiting a two-pronged theoretical first principles and experimental approach herein, we demonstrate for the very first time a solid solution of SnO{sub 2}:10 wt% F containing only 20 at.% IrO{sub 2} [e.g. (Sn{sub 0.80}Ir{sub 0.20})O{sub 2}:10F] displaying remarkably similar electrochemical activity and comparable or even much improved electrochemical durability compared to pure IrO{sub 2}, the accepted gold standard in oxygen evolution electro-catalysts for PEM based water electrolysis. We present the results of these studies.« less

Membrane Contact Sites: Complex Zones for Membrane Association and Lipid Exchange

PubMed Central

Quon, Evan; Beh, Christopher T.

2015-01-01

Lipid transport between membranes within cells involves vesicle and protein carriers, but as agents of nonvesicular lipid transfer, the role of membrane contact sites has received increasing attention. As zones for lipid metabolism and exchange, various membrane contact sites mediate direct associations between different organelles. In particular, membrane contact sites linking the plasma membrane (PM) and the endoplasmic reticulum (ER) represent important regulators of lipid and ion transfer. In yeast, cortical ER is stapled to the PM through membrane-tethering proteins, which establish a direct connection between the membranes. In this review, we consider passive and facilitated models for lipid transfer at PM–ER contact sites. Besides the tethering proteins, we examine the roles of an additional repertoire of lipid and protein regulators that prime and propagate PM–ER membrane association. We conclude that instead of being simple mediators of membrane association, regulatory components of membrane contact sites have complex and multilayered functions. PMID:26949334

Cellulose nanofiber-embedded sulfonated poly (ether sulfone) membranes for proton exchange membrane fuel cells.

PubMed

Xu, Xianlin; Li, Rui; Tang, Chenxiao; Wang, Hang; Zhuang, Xupin; Liu, Ya; Kang, Weimin; Shi, Lei

2018-03-15

Cellulose nanofibers were embedded into sulfonated poly (ether sulfone) matrix to heighten the water retention and proton conductivity of proton exchange membranes (PEMs). Cellulose nanofibers were obtained by hydrolyzing cellulose acetate nanofibers, which were prepared via electrostatic-induction-assisted solution blow spinning. Morphology, thermal stability, and mechanical properties of the PEMs were investigated. The results showed that proton conductivity, water uptake, and methanol permeability of the composite membranes were improved. Hydrophilicity of the composite membranes was gradually improved with the addition of nanofibers. When the content of nanofibers was 5 wt%, the highest proton conductivity was 0.13 S/cm (80 °C, 100% RH). Therefore, the cellulose nanofiber could be used as support materials to enhance the performance of proton exchange membranes, the composite membranes have potential application in Direct methanol fuel cells (DMFCs). Copyright © 2017 Elsevier Ltd. All rights reserved.

A study of water electrolysis using ionic polymer-metal composite for solar energy storage

NASA Astrophysics Data System (ADS)

Keow, Alicia; Chen, Zheng

2017-04-01

Hydrogen gas can be harvested via the electrolysis of water. The gas is then fed into a proton exchange membrane fuel cell (PEMFC) to produce electricity with clean emission. Ionic polymer-metal composite (IPMC), which is made from electroplating a proton-conductive polymer film called Nafion encourages ion migration and dissociation of water under application of external voltage. This property has been proven to be able to act as catalyst for the electrolysis of pure water. This renewable energy system is inspired by photosynthesis. By using solar panels to gather sunlight as the source of energy, the generation of electricity required to activate the IPMC electrolyser is acquired. The hydrogen gas is collected as storable fuel and can be converted back into energy using a commercial fuel cell. The goal of this research is to create a round-trip energy efficient system which can harvest solar energy, store them in the form of hydrogen gas and convert the stored hydrogen back to electricity through the use of fuel cell with minimal overall losses. The effect of increasing the surface area of contact is explored through etching of the polymer electrolyte membrane (PEM) with argon plasma or manually sanding the surface and how it affects the increase of energy conversion efficiency of the electrolyser. In addition, the relationship between temperature and the IPMC is studied. Experimental results demonstrated that increases in temperature of water and changes in surface area contact correlate with gas generation.

In situ investigation on ultrafast oxygen evolution reactions of water splitting in proton exchange membrane electrolyzer cells

DOE PAGES

Mo, Jingke; Kang, Zhenye; Yang, Gaoqiang; ...

2017-08-25

We present that the oxygen evolution reaction (OER) is a half reaction in electrochemical devices, including low-temperature water electrolysis, which is considered as one of the most promising methods to generate hydrogen/oxygen for the storage of energy. It is affected by many factors, and its mechanism is still not completely understood. A proton exchange membrane electrolyzer cell (PEMEC) with optical access to the surface of anode catalyst layer (CL) coupled with a distinguished high-speed and micro-scale visualization system (HMVS) was developed to in situ investigate OERs. It was revealed in real time that OERs only occur on the anode CLmore » adjacent to liquid/gas diffusion layer (LGDL). The CL electrical conductivity plays a crucial role in OERs on CLs. The large in-plane electrical resistance of CLs becomes a threshold of OERs over the entire CL, and causes a lot of catalyst waste in the middle of LGDL pores. Moreover, the oxygen bubble nucleation, growth, and detachment and the effect of current density on those processes were also characterized. Here, this study proposes a new approach for better understanding the mechanisms of OERs and optimizing the design and fabrication of membrane electrode assemblies.« less

In situ investigation on ultrafast oxygen evolution reactions of water splitting in proton exchange membrane electrolyzer cells

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

Mo, Jingke; Kang, Zhenye; Yang, Gaoqiang

We present that the oxygen evolution reaction (OER) is a half reaction in electrochemical devices, including low-temperature water electrolysis, which is considered as one of the most promising methods to generate hydrogen/oxygen for the storage of energy. It is affected by many factors, and its mechanism is still not completely understood. A proton exchange membrane electrolyzer cell (PEMEC) with optical access to the surface of anode catalyst layer (CL) coupled with a distinguished high-speed and micro-scale visualization system (HMVS) was developed to in situ investigate OERs. It was revealed in real time that OERs only occur on the anode CLmore » adjacent to liquid/gas diffusion layer (LGDL). The CL electrical conductivity plays a crucial role in OERs on CLs. The large in-plane electrical resistance of CLs becomes a threshold of OERs over the entire CL, and causes a lot of catalyst waste in the middle of LGDL pores. Moreover, the oxygen bubble nucleation, growth, and detachment and the effect of current density on those processes were also characterized. Here, this study proposes a new approach for better understanding the mechanisms of OERs and optimizing the design and fabrication of membrane electrode assemblies.« less

Optimized anion exchange membranes for vanadium redox flow batteries.

PubMed

Chen, Dongyang; Hickner, Michael A; Agar, Ertan; Kumbur, E Caglan

2013-08-14

In order to understand the properties of low vanadium permeability anion exchange membranes for vanadium redox flow batteries (VRFBs), quaternary ammonium functionalized Radel (QA-Radel) membranes with three ion exchange capacities (IECs) from 1.7 to 2.4 mequiv g(-1) were synthesized and 55-60 μm thick membrane samples were evaluated for their transport properties and in-cell battery performance. The ionic conductivity and vanadium permeability of the membranes were investigated and correlated to the battery performance through measurements of Coulombic efficiency, voltage efficiency and energy efficiency in single cell tests, and capacity fade during cycling. Increasing the IEC of the QA-Radel membranes increased both the ionic conductivity and VO(2+) permeability. The 1.7 mequiv g(-1) IEC QA-Radel had the highest Coulombic efficiency and best cycling capacity maintenance in the VRFB, while the cell's voltage efficiency was limited by the membrane's low ionic conductivity. Increasing the IEC resulted in higher voltage efficiency for the 2.0 and 2.4 mequiv g(-1) samples, but the cells with these membranes displayed reduced Coulombic efficiency and faster capacity fade. The QA-Radel with an IEC of 2.0 mequiv g(-1) had the best balance of ionic conductivity and VO(2+) permeability, achieving a maximum power density of 218 mW cm(-2) which was higher than the maximum power density of a VRFB assembled with a Nafion N212 membrane in our system. While anion exchange membranes are under study for a variety of VRFB applications, this work demonstrates that the material parameters must be optimized to obtain the maximum cell performance.

Multi-layer membrane model for mass transport in a direct ethanol fuel cell using an alkaline anion exchange membrane

NASA Astrophysics Data System (ADS)

Bahrami, Hafez; Faghri, Amir

2012-11-01

A one-dimensional, isothermal, single-phase model is presented to investigate the mass transport in a direct ethanol fuel cell incorporating an alkaline anion exchange membrane. The electrochemistry is analytically solved and the closed-form solution is provided for two limiting cases assuming Tafel expressions for both oxygen reduction and ethanol oxidation. A multi-layer membrane model is proposed to properly account for the diffusive and electroosmotic transport of ethanol through the membrane. The fundamental differences in fuel crossover for positive and negative electroosmotic drag coefficients are discussed. It is found that ethanol crossover is significantly reduced upon using an alkaline anion exchange membrane instead of a proton exchange membrane, especially at current densities higher than 500 A m

Combining Electrolysis and Electroporation for Tissue Ablation.

PubMed

Phillips, Mary; Rubinsky, Liel; Meir, Arie; Raju, Narayan; Rubinsky, Boris

2015-08-01

Electrolytic ablation is a method that operates by delivering low magnitude direct current to the target region over long periods of time, generating electrolytic products that destroy cells. This study was designed to explore the hypothesis stating that electrolytic ablation can be made more effective when the electrolysis-producing electric charges are delivered using electric pulses with field strength typical in reversible electroporation protocols. (For brevity we will refer to tissue ablation protocols that combine electroporation and electrolysis as E(2).) The mechanistic explanation of this hypothesis is related to the idea that products of electrolysis generated by E(2) protocols can gain access to the interior of the cell through the electroporation permeabilized cell membrane and therefore cause more effective cell death than from the exterior of an intact cell. The goal of this study is to provide a first-order examination of this hypothesis by comparing the charge dosage required to cause a comparable level of damage to a rat liver, in vivo, when using either conventional electrolysis or E(2) approaches. Our results show that E(2) protocols produce tissue damage that is consistent with electrolytic ablation. Furthermore, E(2) protocols cause damage comparable to that produced by conventional electrolytic protocols while delivering orders of magnitude less charge to the target tissue over much shorter periods of time. © The Author(s) 2014.

Exploring Alkaline Stable Organic Cations for Polymer Hydroxide Exchange Membranes

DTIC Science & Technology

2015-04-29

1   1.1.2   Proton exchange membrane fuel cells ( PEMFCs ) ......................... 3   1.1.3   Alkaline fuel cells (AFCs...160   xi LIST OF FIGURES Figure 1.1:   Schematic diagram of a PEMFC ...according to the type of electrolyte they use. Nowadays, there are six major types of fuel cells: proton-exchange membrane fuel cells ( PEMFCs ), hydroxide

PEM Electrolysis H2A Production Case Study Documentation

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

James, Brian; Colella, Whitney; Moton, Jennie

2013-12-31

This report documents the development of four DOE Hydrogen Analysis (H2A) case studies for polymer electrolyte membrane (PEM) electrolysis. The four cases characterize PEM electrolyzer technology for two hydrogen production plant sizes (Forecourt and Central) and for two technology development time horizons (Current and Future).

Hydrogen generation by electrolysis of aqueous organic solutions

NASA Technical Reports Server (NTRS)

Jeffries-Nakamura, Barbara (Inventor); Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Valdez, Thomas I. (Inventor)

2006-01-01

A device for electrolysis of an aqueous solution of an organic fuel. The electrolyte is a solid-state polymer membrane with anode and cathode catalysts on both surfaces for electro-oxidization and electro-reduction. A low-cost and portable hydrogen generator can be made based on the device with organic fuels such as methanol.

Hydrogen generation by electrolysis of aqueous organic solutions

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Jeffries-Nakamura, Barbara (Inventor); Valdez, Thomas I. (Inventor)

2002-01-01

A device for electrolysis of an aqueous solution of an organic fuel. The electrolyte is a solid-state polymer membrane with anode and cathode catalysts on both surfaces for electro-oxidization and electro-reduction. A low-cost and portable hydrogen generator can be made based on the device with organic fuels such as methanol.

Study on corrosion migrations within catalyst-coated membranes of proton exchange membrane electrolyzer cells

DOE PAGES

Mo, Jingke; Steen, Stuart; Kang, Zhenye; ...

2017-10-09

The corrosion of low-cost, easily manufactured metallic components inside the electrochemical environment of proton exchange membrane electrolyzer cells (PEMECs) has a significant effect on their performance and durability. Here, 316 stainless steel (SS) mesh was used as a model liquid/gas diffusion layer material to investigate the migration of corrosion products in the catalyst-coated membrane of a PEMEC. Iron and nickel cation particles were found distributed throughout the anode catalyst layer, proton exchange membrane, and cathode catalyst layer, as revealed by scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. Our results indicate the corrosion products of 316 SS are transportedmore » from anode to cathode through the nanochannels of the Nafion membrane, resulting in impeded proton transport and overall PEMEC performance loss.« less

Study on corrosion migrations within catalyst-coated membranes of proton exchange membrane electrolyzer cells

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

Mo, Jingke; Steen, Stuart; Kang, Zhenye

The corrosion of low-cost, easily manufactured metallic components inside the electrochemical environment of proton exchange membrane electrolyzer cells (PEMECs) has a significant effect on their performance and durability. Here, 316 stainless steel (SS) mesh was used as a model liquid/gas diffusion layer material to investigate the migration of corrosion products in the catalyst-coated membrane of a PEMEC. Iron and nickel cation particles were found distributed throughout the anode catalyst layer, proton exchange membrane, and cathode catalyst layer, as revealed by scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. Our results indicate the corrosion products of 316 SS are transportedmore » from anode to cathode through the nanochannels of the Nafion membrane, resulting in impeded proton transport and overall PEMEC performance loss.« less

Membrane device and process for mass exchange, separation, and filtration

DOEpatents

Liu, Wei; Canfield, Nathan L.

2016-11-15

A membrane device and processes for fabrication and for using are disclosed. The membrane device may include a number of porous metal membranes that provide a high membrane surface area per unit volume. The membrane device provides various operation modes that enhance throughput and selectivity for mass exchange, mass transfer, separation, and/or filtration applications between feed flow streams and permeate flow streams.

Preparation and characterization of self-crosslinked organic/inorganic proton exchange membranes

NASA Astrophysics Data System (ADS)

Zhong, Shuangling; Cui, Xuejun; Dou, Sen; Liu, Wencong

A series of silicon-containing sulfonated polystyrene/acrylate (Si-sPS/A) nanoparticles are successfully synthesized via simple emulsion polymerization method. The Si-sPS/A latexes show good film-forming capability and the self-crosslinked organic/inorganic proton exchange membranes are prepared by pouring the Si-sPS/A nanoparticle latexes into glass plates and drying at 60 °C for 10 h and 120 °C for 2 h. The potential of the membranes in direct methanol fuel cells (DMFCs) is characterized preliminarily by studying their thermal stability, ion-exchange capacity, water uptake, methanol diffusion coefficient, proton conductivity and selectivity (proton conductivity/methanol diffusion coefficient). The results indicate that these membranes possess excellent thermal stability and methanol barrier due to the existence of self-crosslinked silica network. In addition, the proton conductivity of the membranes is in the range of 10 -3-10 -2 S cm -1 and all the membranes show much higher selectivity in comparison with Nafion ® 117. These results suggest that the self-crosslinked organic/inorganic proton exchange membranes are particularly promising in DMFC applications.

Membrane water-flow rate in electrolyzer cells with a solid polymer electrolyte (SPE)

NASA Astrophysics Data System (ADS)

Li, Xiaojin; Qu, Shuguo; Yu, Hongmei; Hou, Ming; Shao, Zhigang; Yi, Baolian

Water-flow rate across Nafion membrane in SPE electrolyzer cells was measured and modelled. From the analysis of water transport mechanisms in SPE water electrolysis, the water-flow rate through membrane can be described by the electro-osmotic drag. The calculated electro-osmotic drag coefficients, n d, for the membrane in SPE electrolysis cells at different temperatures were compared with literature and in good agreement with those of Ge et al. and Ise et al. To describe the water-flow rate through membrane more accurately, a linear fit of n d as a function of temperature for the membrane in SPE water electrolysis was proposed in this paper. This paper studied the membrane water-flow rate experimentally and mathematically, which is of importance in the designing and optimization of the process of SPE water electrolysis. This paper also provided a novel method for measuring the electro-osmotic drag coefficient of Nafion membrane in contact with liquid water, acid and methanol solutions, etc.

Predicting Salt Permeability Coefficients in Highly Swollen, Highly Charged Ion Exchange Membranes.

PubMed

Kamcev, Jovan; Paul, Donald R; Manning, Gerald S; Freeman, Benny D

2017-02-01

This study presents a framework for predicting salt permeability coefficients in ion exchange membranes in contact with an aqueous salt solution. The model, based on the solution-diffusion mechanism, was tested using experimental salt permeability data for a series of commercial ion exchange membranes. Equilibrium salt partition coefficients were calculated using a thermodynamic framework (i.e., Donnan theory), incorporating Manning's counterion condensation theory to calculate ion activity coefficients in the membrane phase and the Pitzer model to calculate ion activity coefficients in the solution phase. The model predicted NaCl partition coefficients in a cation exchange membrane and two anion exchange membranes, as well as MgCl 2 partition coefficients in a cation exchange membrane, remarkably well at higher external salt concentrations (>0.1 M) and reasonably well at lower external salt concentrations (<0.1 M) with no adjustable parameters. Membrane ion diffusion coefficients were calculated using a combination of the Mackie and Meares model, which assumes ion diffusion in water-swollen polymers is affected by a tortuosity factor, and a model developed by Manning to account for electrostatic effects. Agreement between experimental and predicted salt diffusion coefficients was good with no adjustable parameters. Calculated salt partition and diffusion coefficients were combined within the framework of the solution-diffusion model to predict salt permeability coefficients. Agreement between model and experimental data was remarkably good. Additionally, a simplified version of the model was used to elucidate connections between membrane structure (e.g., fixed charge group concentration) and salt transport properties.

Technology Status: Fuel Cells and Electrolysis Cells

NASA Technical Reports Server (NTRS)

Mcbryar, H.

1978-01-01

The status of the baselined shuttle fuel cell as well as the acid membrane fuel cell and space-oriented water electrolysis technologies are presented. The more recent advances in the alkaline fuel cell technology area are the subject of a companion paper. A preliminary plan for the focusing of these technologies towards regenerative energy storage applications in the multi-hundred kilowatt range is also discussed.

Protective coatings on stainless steel bipolar plates for proton exchange membrane (PEM) electrolysers

NASA Astrophysics Data System (ADS)

Gago, A. S.; Ansar, S. A.; Saruhan, B.; Schulz, U.; Lettenmeier, P.; Cañas, N. A.; Gazdzicki, P.; Morawietz, T.; Hiesgen, R.; Arnold, J.; Friedrich, K. A.

2016-03-01

Proton exchange membrane (PEM) electrolysis is a promising technology for large H2 production from surplus electricity from renewable sources. However, the electrolyser stack is costly due to the manufacture of bipolar plates (BPP). Stainless steel can be used as an alternative, but it must be coated. Herein, dense titanium coatings are produced on stainless steel substrates by vacuum plasma spraying (VPS). Further surface modification of the Ti coating with Pt (8 wt% Pt/Ti) deposited by physical vapour deposition (PVD) magnetron sputtering reduces the interfacial contact resistance (ICR). The Ti and Pt/Ti coatings are characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron microscopy (XPS). Subsequently, the coatings are evaluated in simulated and real PEM electrolyser environments, and they managed to fully protect the stainless steel substrate. In contrast, the absence of the thermally sprayed Ti layer between Pt and stainless steel leads to pitting corrosion. The Pt/Ti coating is tested in a PEM electrolyser cell for almost 200 h, exhibiting an average degradation rate of 26.5 μV h-1. The results reported here demonstrate the possibility of using stainless steel as a base material for the stack of a PEM electrolyser.

Method of detecting defects in ion exchange membranes of electrochemical cells by chemochromic sensors

DOEpatents

Brooker, Robert Paul; Mohajeri, Nahid

2016-01-05

A method of detecting defects in membranes such as ion exchange membranes of electrochemical cells. The electrochemical cell includes an assembly having an anode side and a cathode side with the ion exchange membrane in between. In a configuration step a chemochromic sensor is placed above the cathode and flow isolation hardware lateral to the ion exchange membrane which prevents a flow of hydrogen (H.sub.2) between the cathode and anode side. The anode side is exposed to a first reactant fluid including hydrogen. The chemochromic sensor is examined after the exposing for a color change. A color change evidences the ion exchange membrane has at least one defect that permits H.sub.2 transmission therethrough.

Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

PubMed

Sljukić, Biljana; Morais, Ana L; Santos, Diogo M F; Sequeira, César A C

2012-07-19

Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC's performance. Cell polarization, power density, stability, and durability tests are used in the membranes' evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

Porous PVDF/PANI ion-exchange membrane (IEM) modified by polyvinylpyrrolidone (PVP) and lithium chloride in the application of membrane capacitive deionisation (MCDI).

PubMed

Zhang, Yiming; Zhang, Wei; Cházaro-Ruiz, Luis F

2018-05-01

In this work, polyvinylidene fluoride (PVDF)/polyaniline (PANI) heterogeneous anion-exchange membranes filled with pore-forming agents polyvinylpyrrolidone (PVP) and lithium chloride were prepared by the solution-casting technique using the solvent 1-methyl-2-pyrrolidone (NMP) and a two-step phase inversion procedure. Key properties of the as-prepared membranes, such as hydrophilicity, water content, ion exchange capacity, fixed ion concentration, conductivity and transport number were examined and compared between membranes in different conditions. The pore-forming hydrophilic additives PVP and lithium chloride to the casting solution appeared to improve the ion-exchange membranes (IEMs) by increasing the conductivity, transport number and hydrophilicity. The effects of increasing membrane drying time on the porosity of the as-prepared membranes were found to lower membrane porosity by reducing membrane water content. However, pore-forming agents were found to be able to stabilise membrane transport number with different drying times. As-prepared PVDF/PANI anion-exchange membrane with pore-forming agent is demonstrated to be a more efficient candidate for water purification (e.g. desalination) and other industrial applications.

Elucidating Performance Limitations in Alkaline-Exchange- Membrane Fuel Cells

DOE PAGES

Shiau, Huai-Suen; Zenyuk, Iryna V.; Weber, Adam Z.

2017-07-15

Water management is a serious concern for alkaline-exchange-membrane fuel cells (AEMFCs) because water is a reactant in the alkaline oxygen-reduction reaction and hydroxide conduction in alkaline-exchange membranes is highly hydration dependent. Here in this article, we develop and use a multiphysics, multiphase model to explore water management in AEMFCs. We demonstrate that the low performance is mostly caused by extremely non-uniform distribution of water in the ionomer phase. A sensitivity analysis of design parameters including humidification strategies, membrane properties, and water transport resistance was undertaken to explore possible optimization strategies. Furthermore, the strategy and issues of reducing bicarbonate/carbonate buildup inmore » the membrane-electrode assembly with CO 2 from air is demonstrated based on the model prediction. Overall, mathematical modeling is used to explore trends and strategies to overcome performance bottlenecks and help enable AEMFC commercialization.« less

Nanocomposite membranes based on polybenzimidazole and ZrO2 for high-temperature proton exchange membrane fuel cells.

PubMed

Nawn, Graeme; Pace, Giuseppe; Lavina, Sandra; Vezzù, Keti; Negro, Enrico; Bertasi, Federico; Polizzi, Stefano; Di Noto, Vito

2015-04-24

Owing to the numerous benefits obtained when operating proton exchange membrane fuel cells at elevated temperature (>100 °C), the development of thermally stable proton exchange membranes that demonstrate conductivity under anhydrous conditions remains a significant goal for fuel cell technology. This paper presents composite membranes consisting of poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI4N) impregnated with a ZrO2 nanofiller of varying content (ranging from 0 to 22 wt %). The structure-property relationships of the acid-doped and undoped composite membranes have been studied using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, wide-angle X-ray scattering, infrared spectroscopy, and broadband electrical spectroscopy. Results indicate that the level of nanofiller has a significant effect on the membrane properties. From 0 to 8 wt %, the acid uptake as well as the thermal and mechanical properties of the membrane increase. As the nanofiller level is increased from 8 to 22 wt % the opposite effect is observed. At 185 °C, the ionic conductivity of [PBI4N(ZrO2 )0.231 ](H3 PO4 )13 is found to be 1.04×10(-1)  S cm(-1) . This renders membranes of this type promising candidates for use in high-temperature proton exchange membrane fuel cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ion-Exchanged SAPO-34 membranes for Krypton-Xenon Separation: Control of Permeation Properties and Fabrication of Hollow Fiber Membranes

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

Kwon, Yeon Hye; Min, Byunghyun; Yang, Shaowei

Separation of radioisotope 85Kr from 136Xe is of importance in used nuclear fuel reprocessing. Membrane separation based on zeolite molecular sieves such as chabazite SAPO- 34 is an attractive alternative to energy-intensive cryogenic distillation. We report the synthesis of SAPO-34 membranes with considerably enhanced performance, via thickness reduction based upon control of a steam-assisted vapor-solid conversion technique followed by ion exchange with alkali metal cations. The reduction of membrane thickness leads to a large increase in Kr permeance from 7.5 gas permeation units (GPU) to 26.3 GPU with ideal Kr/Xe selectivities > 20 at 298 K. Cation-exchanged membranes show largemore » (>50%) increases in selectivity at ambient or slight sub-ambient conditions. The adsorption, diffusion, and permeation characteristics of ionexchanged SAPO-34 materials and membranes are investigated in detail, with potassium exchanged SAPO-34 membranes showing particularly attractive performance. Lastly, we then demonstrate the fabrication of selective SAPO-34 membranes on α-alumina hollow fibers.« less

Ion-Exchanged SAPO-34 membranes for Krypton-Xenon Separation: Control of Permeation Properties and Fabrication of Hollow Fiber Membranes

DOE PAGES

Kwon, Yeon Hye; Min, Byunghyun; Yang, Shaowei; ...

2018-01-29

Separation of radioisotope 85Kr from 136Xe is of importance in used nuclear fuel reprocessing. Membrane separation based on zeolite molecular sieves such as chabazite SAPO- 34 is an attractive alternative to energy-intensive cryogenic distillation. We report the synthesis of SAPO-34 membranes with considerably enhanced performance, via thickness reduction based upon control of a steam-assisted vapor-solid conversion technique followed by ion exchange with alkali metal cations. The reduction of membrane thickness leads to a large increase in Kr permeance from 7.5 gas permeation units (GPU) to 26.3 GPU with ideal Kr/Xe selectivities > 20 at 298 K. Cation-exchanged membranes show largemore » (>50%) increases in selectivity at ambient or slight sub-ambient conditions. The adsorption, diffusion, and permeation characteristics of ionexchanged SAPO-34 materials and membranes are investigated in detail, with potassium exchanged SAPO-34 membranes showing particularly attractive performance. Lastly, we then demonstrate the fabrication of selective SAPO-34 membranes on α-alumina hollow fibers.« less

Preparation and performance evaluation of novel alkaline stable anion exchange membranes

NASA Astrophysics Data System (ADS)

Irfan, Muhammad; Bakangura, Erigene; Afsar, Noor Ul; Hossain, Md. Masem; Ran, Jin; Xu, Tongwen

2017-07-01

Novel alkaline stable anion exchange membranes are prepared from various amounts of N-methyl dipicolylamine (MDPA) and brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO). The dipicolylamine and MDPA are synthesized through condensation reaction and confirmed by 1H NMR spectroscopy. The morphologies of prepared membranes are investigated by atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), 1H NMR spectroscopy and scanning electron microscopy (SEM). The electrochemical and physical properties of AEMs are tested comprising water uptake (WU), ion exchange capacity (IEC), alkaline stability, linear expansion ratio (LER), thermal stability and mechanical stability. The obtained hydroxide conductivity of MDPA-4 is 66.5 mS/cm at 80 °C. The MDPA-4 membrane shows good alkaline stability, high hydroxide conductivity, low methanol permeability (3.43 × 10-7 cm2/s), higher selectivity (8.26 × 107 mS s/cm3), less water uptake (41.1%) and lower linear expansion (11.1%) despite of high IEC value (1.62 mmol/g). The results prove that MDPA membranes have great potential application in anion exchange membrane fuel cell.

Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

PubMed Central

Šljukić, Biljana; Morais, Ana L.; Santos, Diogo M. F.; Sequeira, César A. C.

2012-01-01

Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load. PMID:24958292

The application of Dow Chemical's perfluorinated membranes in proton-exchange membrane fuel cells

NASA Technical Reports Server (NTRS)

Eisman, G. A.

1989-01-01

Dow Chemical's research activities in fuel cell devices revolves around the development and subsequent investigation of the perfluorinated inomeric membrane separator useful in proton-exchange membrane systems. Work is currently focusing on studying the effects of equivalent weight, thickness, water of hydration, pretreatment procedures, as well as the degree of water management required for a given membrane separator in the cell. The presentation will include details of certain aspects of the above as well as some of the requirements for high and low power generation.

Novel structure design of composite proton exchange membranes with continuous and through-membrane proton-conducting channels

NASA Astrophysics Data System (ADS)

Wang, Hang; Tang, Chenxiao; Zhuang, Xupin; Cheng, Bowen; Wang, Wei; Kang, Weimin; Li, Hongjun

2017-10-01

The primary goal of this study is to develop a high-performanced proton exchange membrane with the characteristics of through-membrane and continuous solution blown nanofibers as proton-conducting channels. The curled sulfonated phenolphthalein poly (ether sulfone) and poly (vinylidene fluoride) nanofibers were separately fabricated through the solution blowing process which is a new nanofiber fabricating method with high productivity, then they were fabricated into a sandwich-structured mat. Then this sandwich-structured mat was hot-pressed to form the designed structure using different melting temperatures of the two polymers by melting and making poly (vinylidene fluoride) flow into the phenolphthalein poly (ether sulfone) nanofiber mat. The characteristics of the composite membrane, such as morphology and performance of the membrane, were investigated. The characterization results proved the successful preparation of the membrane structure. Performance results showed that the novel structured membrane with through-membrane nanofibers significantly improved water swelling and methanol permeability, though its conductivity is lower than that of Nafion, the cell performance showed comparable results. Therefore, the novel structure design can be considered as a promising method for preparing of proton exchange membranes.

Fibrinogen Reduction During Selective Plasma Exchange due to Membrane Fouling.

PubMed

Ohkubo, Atsushi; Okado, Tomokazu; Miyamoto, Satoko; Hashimoto, Yurie; Komori, Shigeto; Yamamoto, Motoki; Maeda, Takuma; Itagaki, Ayako; Yamamoto, Hiroko; Seshima, Hiroshi; Kurashima, Naoki; Iimori, Soichiro; Naito, Shotaro; Sohara, Eisei; Uchida, Shinichi; Rai, Tatemitsu

2017-06-01

Fibrinogen is substantially reduced by most plasmapheresis modalities but retained in selective plasma exchange using Evacure EC-4A10 (EC-4A). Although EC-4A's fibrinogen sieving coefficient is 0, a session of selective plasma exchange reduced fibrinogen by approximately 19%. Here, we investigated sieving coefficient in five patients. When the mean processed plasma volume was 1.15 × plasma volume, the mean reduction of fibrinogen during selective plasma exchange was approximately 15%. Fibrinogen sieving coefficient was 0 when the processed plasma volume was 1.0 L, increasing to 0.07 when the processed plasma volume was 3.0 L, with a mean of 0.03 during selective plasma exchange. When fibrinogen sieving coefficient was 0, selective plasma exchange reduced fibrinogen by approximately 10%. Scanning electron microscopy images revealed internal fouling of EC-4A's hollow fiber membrane by substances such as fibrinogen fibrils. Thus, fibrinogen reduction by selective plasma exchange may be predominantly caused by membrane fouling rather than filtration. © 2017 International Society for Apheresis, Japanese Society for Apheresis, and Japanese Society for Dialysis Therapy.

Recycling of Magnesium Alloy Employing Refining and Solid Oxide Membrane (SOM) Electrolysis

NASA Astrophysics Data System (ADS)

Guan, Xiaofei; Zink, Peter A.; Pal, Uday B.; Powell, Adam C.

2013-04-01

Pure magnesium was recycled from partially oxidized 50.5 wt pct Mg-Al scrap alloy and AZ91 Mg alloy (9 wt pct Al, 1 wt pct Zn). Refining experiments were performed using a eutectic mixture of MgF2-CaF2 molten salt (flux). During the experiments, potentiodynamic scans were performed to determine the electrorefining potentials for magnesium dissolution and magnesium bubble nucleation in the flux. The measured electrorefining potential for magnesium bubble nucleation increased over time as the magnesium content inside the magnesium alloy decreased. Potentiostatic holds and electrochemical impedance spectroscopy were employed to measure the electronic and ionic resistances of the flux. The electronic resistivity of the flux varied inversely with the magnesium solubility. Up to 100 pct of the magnesium was refined from the Mg-Al scrap alloy by dissolving magnesium and its oxide into the flux followed by argon-assisted evaporation of dissolved magnesium and subsequently condensing the magnesium vapor. Solid oxide membrane electrolysis was also employed in the system to enable additional magnesium recovery from magnesium oxide in the partially oxidized Mg-Al scrap. In an experiment employing AZ91 Mg alloy, only the refining step was carried out. The calculated refining yield of magnesium from the AZ91 alloy was near 100 pct.

The application of Dow Chemical's perfluorinated membranes in proton-exchange membrane fuel cells

NASA Technical Reports Server (NTRS)

Eisman, G. A.

1989-01-01

Dow Chemical's research activities in fuel cells revolve around the development of perfluorosulfonic acid membranes useful as the proton transport medium and separator. Some of the performance characteristics which are typical for such membranes are outlined. The results of tests utilizing a new experimental membrane useful in proton-exchange membrane fuel cells are presented. The high voltage at low current densities can lead to higher system efficiencies while, at the same time, not sacrificing other critical properties pertinent to membrane fuel cell operation. A series of tests to determine response times indicated that on-off cycles are on the order of 80 milliseconds to reach 90 percent of full power. The IR free voltage at 100 amps/sq ft was determined and the results indicating a membrane/electrode package resistance to be .15 ohm-sq cm at 100 amps/sq ft.

Evaluation of disinfective potential of reactivated free chlorine in pooled tap water by electrolysis.

PubMed

Nakajima, Norihito; Nakano, Takashi; Harada, Fumiue; Taniguchi, Hiromasa; Yokoyama, Isao; Hirose, Jun; Daikoku, Eriko; Sano, Kouichi

2004-05-01

Tap water is one of the causative factors of hospital infections. We examined the disinfective potential of electrolysis and mechanism of disinfection, and clarified the disinfective effect of electrolysis on tap water contaminated with bacteria, and discussed its clinical applications. Tap waters artificially contaminated with Pseudomonas aeruginosa, Escherichia coli, Legionella pneumophila, and Staphylococcus aureus could be sterilized by electrolysis at 20-30 mA for 5 min. A high-density suspension (10(6) CFU/ml) of a spore forming bacterium, Bacillus subtilis was not completely sterilized by electrolysis at 50 mA up to 30 min, but a low-density suspension (10(5) CFU/ml) was totally sterilized by electrolysis at 50 mA for 5 min. Electrolyzed P. aeruginosa changed morphologically, that is, there was bleb formation on the cell wall and irregular aggregation of cytoplasmic small granules. Moreover, cytoplasmic enzyme, nitrate reductase, was inactivated by the electrolysis. On the other hand, genomic DNA of the electrolyzed bacteria was not degenerated, therefore, their DNA polymerase activity was not completely inactivated. Consequently, the major agent in electrolysis for bactericidal action was considered to be free chlorine, and the possible bactericidal mechanism was by destruction of bacterial membranes, followed by the aggregation of peripheral cytoplasmic proteins. Electrolysis of tap water for both disinfecting contaminating bacteria and increasing the disinfectant capacity was considered effective with some limitations, particularly against high-density contamination by spore-forming bacteria. In clinical settings, electrolysis of tap water is considered effective to disinfect water for hand washing in operation theatres, and bathing water for immunocompromised hosts.

Membrane permeation process for dehydration of organic liquid mixtures using sulfonated ion-exchange polyalkene membranes

DOEpatents

Cabasso, Israel; Korngold, Emmanuel

1988-01-01

A membrane permeation process for dehydrating a mixture of organic liquids, such as alcohols or close boiling, heat sensitive mixtures. The process comprises causing a component of the mixture to selectively sorb into one side of sulfonated ion-exchange polyalkene (e.g., polyethylene) membranes and selectively diffuse or flow therethrough, and then desorbing the component into a gas or liquid phase on the other side of the membranes.

Sulfated Titania-Silica Reinforced Nafion Nanocomposite Membranes for Proton Exchange Membrane Fuel Cells.

PubMed

Abu Sayeed, M D; Kim, Hee Jin; Gopalan, A I; Kim, Young Ho; Lee, Kwang-Pill; Choi, Sang-June

2015-09-01

Sulfated titania-silica (SO4(2-)-/TiO2-SiO2) composites were prepared by a sol-gel method with sulfate reaction and characterized by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The nanometric diameter and geometry of the sulfated titania-silica (STS) was investigated by transmission electron microscopy (TEM). A small amount of the STS composite in the range of 0.5-3 wt% was then added as reinforcing into the Nafion membrane by water-assisted solution casting method to prepare STS reinforced Nafion nanocomposite membranes (STS-Nafion nanocomposite membranes). The additional functional groups, sulfate groups, of the nanocomposite membrane having more surface oxygenated groups enhanced the fuel cell membrane properties. The STS-Nafion nanocomposite membranes exhibited improved water uptake compared to that of neat Nafion membranes, whereas methanol uptake values were decreased dramatically improved thermal property of the prepared nanocomposite membranes were measured by thermogravimetric analysis (TGA). Furthermore, increased ion exchange capacity values were obtained by thermoacidic pretreatment of the nanocomposite membranes.

Multi-block sulfonated poly(phenylene) copolymer proton exchange membranes

DOEpatents

Fujimoto, Cy H [Albuquerque, NM; Hibbs, Michael [Albuquerque, NM; Ambrosini, Andrea [Albuquerque, NM

2012-02-07

Improved multi-block sulfonated poly(phenylene) copolymer compositions, methods of making the same, and their use as proton exchange membranes (PEM) in hydrogen fuel cells, direct methanol fuel cells, in electrode casting solutions and electrodes. The multi-block architecture has defined, controllable hydrophobic and hydrophilic segments. These improved membranes have better ion transport (proton conductivity) and water swelling properties.

Application of Novel Anion-Exchange Blend Membranes (AEBMs) to Vanadium Redox Flow Batteries.

PubMed

Cho, Hyeongrae; Krieg, Henning M; Kerres, Jochen A

2018-06-19

Both cation-exchange membranes and anion-exchange membranes are used as ion conducting membranes in vanadium redox flow batteries (VRFBs). Anion-exchange membranes (AEMs) are applied in vanadium redox flow batteries due to the high blocking property of vanadium ions via the Donnan exclusion effect. In this study, novel anion-exchange blend membranes (AEBMs) were prepared, characterized, and applied in VRFBs. Bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide), poly[(1-(4,4′-diphenylether)-5-oxybenzimidazole)-benzimidazole] (PBI-OO) and sulfonated polyether sulfone polymer were combined to prepare 3-component AEBMs with 1,2,4,5-tetramethylimidazole (TMIm) for quaternization. 3-component AEBMs showed significantly enhanced chemical and mechanical properties compared with those of 2-component AEBMs, resulting in an improved performance in VRFBs. The compositions of the anion-exchange polymers in 3-component AEBMs were systematically varied to optimize the AEBMs for the redox-flow battery application. While the 3-component AEBMs showed comparable efficiencies with Nafion ® 212 membranes, they displayed improved vanadium ions cross-over as was confirmed by open circuit voltage tests and capacity fade tests conducted in VRFBs. In addition, one of the synthesized 3-component AEBM had a superior coulombic efficiency and capacity retention in a charging⁻discharging test over 300 cycles at a current density of 40 mA/cm². It can thus be concluded that 3-component AEBMs are promising candidates for long-term operation in VRFBs.

Interfacial Water-Transport Effects in Proton-Exchange Membranes

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

Kienitz, Brian; Yamada, Haruhiko; Nonoyama, Nobuaki

2009-11-19

It is well known that the proton-exchange membrane is perhaps the most critical component of a polymer-electrolyte fuel cell. Typical membranes, such as Nafion(R), require hydration to conduct efficiently and are instrumental in cell water management. Recently, evidence has been shown that these membranes might have different interfacial morphology and transport properties than in the bulk. In this paper, experimental data combined with theoretical simulations will be presented that explore the existence and impact of interfacial resistance on water transport for Nafion(R) 21x membranes. A mass-transfer coefficient for the interfacial resistance is calculated from experimental data using different permeation cells.more » This coefficient is shown to depend exponentially on relative humidity or water activity. The interfacial resistance does not seem to exist for liquid/membrane or membrane/membrane interfaces. The effect of the interfacial resistance is to flatten the water-content profiles within the membrane during operation. Under typical operating conditions, the resistance is on par with the water-transport resistance of the bulk membrane. Thus, the interfacial resistance can be dominant especially in thin, dry membranes and can affect overall fuel-cell performance.« less

Stability and Degradation Mechanisms of Radiation-Grafted Polymer Electrolyte Membranes for Water Electrolysis.

PubMed

Albert, Albert; Lochner, Tim; Schmidt, Thomas J; Gubler, L

2016-06-22

Radiation-grafted membranes are a promising alternative to commercial membranes for water electrolyzers, since they exhibit lower hydrogen crossover and area resistance, better mechanical properties, and are of potentially lower cost than perfluoroalkylsulfonic acid membranes, such as Nafion. Stability is an important factor in view of the expected lifetime of 40 000 h or more of an electrolyzer. In this study, combinations of styrene (St), α-methylstyrene (AMS), acrylonitrile (AN), and 1,3-diisopropenylbenzene (DiPB) are cografted into 50 μm preirradiated poly(ethylene-co-tetrafluoroethylene) (ETFE) base film, followed by sulfonation to produce radiation-grafted membranes. The stability of the membranes with different monomer combinations is compared under an accelerated stress test (AST), and the degradation mechanisms are investigated. To mimic the conditions in an electrolyzer, in which the membrane is always in contact with liquid water at elevated temperature, the membranes are immersed in water for 5 days at 90 °C, so-called thermal stress test (TST). In addition to testing in air atmosphere tests are also carried out under argon to investigate the effect of the absence of oxygen. The water is analyzed with UV-vis spectroscopy and ion chromatography. The ion exchange capacity (IEC), swelling degree, and Fourier transform infrared (FTIR) spectra of the membranes are compared before and after the test. Furthermore, energy-dispersive X-ray (EDX) spectroscopic analysis of the membrane cross-section is performed. Finally, the influence of the TST to the membrane area resistance and hydrogen crossover is measured. The stability increases along the sequence St/AN, St/AN/DiPB, AMS/AN, and AMS/AN/DiPB grafted membrane. The degradation at the weak-link, oxygen-induced degradation, and hydrothermal degradation are proposed in addition to the "swelling-induced detachment" reported in the literature. By mitigating the possible paths of degradation, the AMS

The suitability of monopolar and bipolar ion exchange membranes as separators for biological fuel cells.

PubMed

Harnisch, Falk; Schröder, Uwe; Scholz, Fritz

2008-03-01

A proton exchange (Nafion-117), a cation exchange (Ultrex CMI7000), an anion exchange (Fumasep FAD), and a bipolar (FumasepFBM) membrane have been studied to evaluate the principle suitability of ion exchange membranes as separators between the anode and the cathode compartment of biological fuel cells. The applicability of these membranes is severely affected by the neutral pH, and the usually low ionic strength of the electrolyte solutions. Thus, the ohmic resistance of the monopolar membranes was found to greatly increase at neutral pH and at decreasing electrolyte concentrations. None of the studied membranes can prevent the acidification of the anode and the alkalization of the cathode compartment, which occurs in the course of the fuel cell operation. Bipolar membranes are shown to be least suitable for biofuel cell application since they show the highest polarization without being able to prevent pH splitting between the anode and cathode compartments.

Cast and 3D printed ion exchange membranes for monolithic microbial fuel cell fabrication

NASA Astrophysics Data System (ADS)

Philamore, Hemma; Rossiter, Jonathan; Walters, Peter; Winfield, Jonathan; Ieropoulos, Ioannis

2015-09-01

We present novel solutions to a key challenge in microbial fuel cell (MFC) technology; greater power density through increased relative surface area of the ion exchange membrane that separates the anode and cathode electrodes. The first use of a 3D printed polymer and a cast latex membrane are compared to a conventionally used cation exchange membrane. These new techniques significantly expand the geometric versatility available to ion exchange membranes in MFCs, which may be instrumental in answering challenges in the design of MFCs including miniaturisation, cost and ease of fabrication. Under electrical load conditions selected for optimal power transfer, peak power production (mean 10 batch feeds) was 11.39 μW (CEM), 10.51 μW (latex) and 0.92 μW (Tangoplus). Change in conductivity and pH of anolyte were correlated with MFC power production. Digital and environmental scanning electron microscopy show structural changes to and biological precipitation on membrane materials following long term use in an MFC. The cost of the novel membranes was lower than the conventional CEM. The efficacy of two novel membranes for ion exchange indicates that further characterisation of these materials and their fabrication techniques, shows great potential to significantly increase the range and type of MFCs that can be produced.

21 CFR 173.20 - Ion-exchange membranes.

Code of Federal Regulations, 2011 CFR

2011-04-01

... ion-exchange membrane is prepared by subjecting a polyethylene base conforming to § 177.1520 of this chapter to polymerization with styrene until the polystyrene phase of the base is not less than 16 percent nor more than 30 percent by weight. The base is then modified by reaction with chloromethyl methyl...

21 CFR 173.20 - Ion-exchange membranes.

Code of Federal Regulations, 2013 CFR

2013-04-01

... ion-exchange membrane is prepared by subjecting a polyethylene base conforming to § 177.1520 of this chapter to polymerization with styrene until the polystyrene phase of the base is not less than 16 percent nor more than 30 percent by weight. The base is then modified by reaction with chloromethyl methyl...

21 CFR 173.20 - Ion-exchange membranes.

Code of Federal Regulations, 2012 CFR

2012-04-01

... ion-exchange membrane is prepared by subjecting a polyethylene base conforming to § 177.1520 of this chapter to polymerization with styrene until the polystyrene phase of the base is not less than 16 percent nor more than 30 percent by weight. The base is then modified by reaction with chloromethyl methyl...

21 CFR 173.20 - Ion-exchange membranes.

Code of Federal Regulations, 2010 CFR

2010-04-01

... ion-exchange membrane is prepared by subjecting a polyethylene base conforming to § 177.1520 of this chapter to polymerization with styrene until the polystyrene phase of the base is not less than 16 percent nor more than 30 percent by weight. The base is then modified by reaction with chloromethyl methyl...

Nitrate determination using anion exchange membrane and mid-infrared spectroscopy.

PubMed

Linker, Raphael; Shaviv, Avi

2006-09-01

This study investigates the combined use of an anion exchange membrane and transmittance mid-infrared spectroscopy for determining nitrate concentration in aqueous solutions and soil pastes. The method is based on immersing a small piece (2 cm(2)) of anion exchange membrane into 5 mL of solution or soil paste for 30 minutes, after which the membrane is removed, rinsed, and wiped dry. The absorbance spectrum of the charged membrane is then used to determine the amount of nitrate sorbed on the membrane. At the levels tested, the presence of carbonate or phosphate does not affect the nitrate sorption or the spectrum of the charged membrane in the vicinity of the nitrate band. Sulfate affects the spectrum of the charged membrane but does not prevent nitrate determination. For soil pastes, nitrate sorption is remarkably independent of the soil composition and is not affected by the level of soil constituents such as organic matter, clay, and calcium carbonate. Partial least squares analysis of the membrane spectra shows that there exists a strong correlation between the nitrate charge and the absorbance in the 1000-1070 cm(-1) interval, which includes the v(1) nitrate band located around 1040 cm(-1). The prediction errors range from 0.8 to 2.1 mueq, which, under the specific experimental conditions, corresponds to approximately 2 to 6 ppm N-NO(3)(-) on a solution basis or 2 to 5 mg [N]/kg [dry soil] on a dry soil basis.

Novel fluoropolymer anion exchange membranes for alkaline direct methanol fuel cells.

PubMed

Zhang, Yanmei; Fang, Jun; Wu, Yongbin; Xu, Hankun; Chi, Xianjun; Li, Wei; Yang, Yixu; Yan, Ge; Zhuang, Yongze

2012-09-01

A series of novel fluoropolymer anion exchange membranes based on the copolymer of vinylbenzyl chloride, butyl methacrylate, and hexafluorobutyl methacrylate has been prepared. Fourier transform infrared (FT-IR) spectroscopy and elemental analysis techniques are used to study the chemical structure and chemical composition of the membranes. The water uptake, ion-exchange capacity (IEC), conductivity, methanol permeability, and chemical stability of the membranes are also determined. The membranes exhibit high anionic conductivity in deionized water at 65 °C ranging from 3.86×10(-2) S cm(-1) to 4.36×10(-2) S cm(-1). The methanol permeability coefficients of the membranes are in the range of 4.21-5.80×10(-8) cm(2) s(-1) at 65 °C. The novel membranes also show good chemical and thermal stability. An open-circuit voltage of 0.7 V and a maximum power density of 53.2 mW cm(-2) of alkaline direct methanol fuel cell (ADMFC) with the membrane C, 1 M methanol, 1 M NaOH, and humidified oxygen are achieved at 65 °C. Therefore, these membranes have great potential for applications in fuel cell systems. Copyright © 2012 Elsevier Inc. All rights reserved.

Performance of polyethylene based radiation grafted anion exchange membrane with polystyrene-b-poly (ethylene/butylene)-b-polystyrene based ionomer using NiCo2O4 catalyst for water electrolysis

NASA Astrophysics Data System (ADS)

Gupta, Gaurav; Scott, Keith; Mamlouk, Mohamed

2018-01-01

A soluble anion exchange ionomer with high OH- ion conductivity comparable to that of H+ conductivity of Nafion is synthesised by chloromethylation of polystyrene-b-poly (ethylene/butylene)-b-polystyrene (SEBS) and used with NiCo2O4 electro-catalyst for water electrolysis. The ionomer has an ion exchange capacity of 1.9 mmol g-1 and ionic conductivity of 0.14 S cm-2 at 50 °C. The cell voltage at 20 °C at 100 mA cm-2 is 1.77 and 1.72 V in, 0.1 and 1.0 M NaOH, respectively, for an optimum loading of 10 mg cm-2 NiCo2O4. At 10 mg cm-2 NiCo2O4 electrolyser cell performance is at least equal to or superior to that of IrO2 at 2 mg cm-2 with excellent stability over 1 h. When the catalyst is sprayed on the GDL instead of CCM, the performance is further improved to 1.65 V at 100 mA cm-2 at 60 °C & 0.1 M KOH. The limited AEM electrolyser performance when operating with deionised water in comparison to PEM and alkaline electrolyser arises from the sluggish OER in the AEM environment equivalent to pH of 11.5 and the two orders of magnitude lower HER activity with respect to acid medium combined with the high Tafel slope of 120 mV dec-1.

Thin Robust Anion Exchange Membranes for Fuel Cell Applications

DTIC Science & Technology

2014-01-01

water diffsuion. Here we use a Polyphenylene Oxide dibock polymer co-polymerized with polyvinyl benzyl trimethyl ammonium blocks ( PPO -b-PVBTMA[F...in PPO -b-PVBTMA[F-] AEM under saturated humidity environment ECS Transactions, 64 (3) 1185-1194 (2014) 1191 Conductivity of this membrane was...makes it a promising material for applications in anion exchange membrane fuel cells. Figure 5: Conductivity of PPO -b-PVBTMA[F-] under 95% Relative

2D fluorescence spectroscopy for monitoring ion-exchange membrane based technologies - Reverse electrodialysis (RED).

PubMed

Pawlowski, Sylwin; Galinha, Claudia F; Crespo, João G; Velizarov, Svetlozar

2016-01-01

Reverse electrodialysis (RED) is one of the emerging, membrane-based technologies for harvesting salinity gradient energy. In RED process, fouling is an undesirable operation constraint since it leads to a decrease of the obtainable net power density due to increasing stack electric resistance and pressure drop. Therefore, early fouling detection is one of the main challenges for successful RED technology implementation. In the present study, two-dimensional (2D) fluorescence spectroscopy was used, for the first time, as a tool for fouling monitoring in RED. Fluorescence excitation-emission matrices (EEMs) of ion-exchange membrane surfaces and of natural aqueous streams were acquired during one month of a RED stack operation. Fouling evolvement on the ion-exchange membrane surfaces was successfully followed by 2D fluorescence spectroscopy and quantified using principal components analysis (PCA). Additionally, the efficiency of cleaning strategy was assessed by measuring the membrane fluorescence emission intensity before and after cleaning. The anion-exchange membrane (AEM) surface in contact with river water showed to be significantly affected due to fouling by humic compounds, which were found to cross through the membrane from the lower salinity (river water) to higher salinity (sea water) stream. The results obtained show that the combined approach of using 2D fluorescence spectroscopy and PCA has a high potential for studying fouling development and membrane cleaning efficiency in ion exchange membrane processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modeling the ion transfer and polarization of ion exchange membranes in bioelectrochemical systems.

PubMed

Harnisch, Falk; Warmbier, Robert; Schneider, Ralf; Schröder, Uwe

2009-06-01

An explicit numerical model for the charge balancing ion transfer across monopolar ion exchange membranes under conditions of bioelectrochemical systems is presented. Diffusion and migration equations have been solved according to the Nernst-Planck Equation and the resulting ion concentrations, pH values and the resistance values of the membrane for different conditions were computed. The modeling results underline the principle limitations of the application of ion exchange membranes in biological fuel cells and electrolyzers, caused by the inherent occurrence of a pH-gradient between anode and cathode compartment, and an increased ohmic membrane resistance at decreasing electrolyte concentrations. Finally, the physical and numerical limitations of the model are discussed.

SPEEK/PVDF/PES Composite as Alternative Proton Exchange Membrane for Vanadium Redox Flow Batteries

NASA Astrophysics Data System (ADS)

Fu, Zhimin; Liu, Jinying; Liu, Qifeng

2016-01-01

A membrane consisting of a blend of sulfonated poly(ether ether ketone) (SPEEK), poly(vinylidene fluoride) (PVDF), and poly(ether sulfone) (PES) has been fabricated and used as an ion exchange membrane for application in vanadium redox flow batteries (VRBs). The vanadium ion permeability of the SPEEK/PVDF/PES membrane was one order of magnitude lower than that of Nafion 117 membrane. The low-cost composite membrane exhibited better performance than Nafion 117 membrane at the same operating condition. A VRB single cell with SPEEK/PVDF/PES membrane showed significantly lower capacity loss, higher coulombic efficiency (>95%), and higher energy efficiency (>82%) compared with Nafion 117 membrane. In the self-discharge test, the duration of the cell with the SPEEK/PVDF/PES membrane was nearly two times longer than that with Nafion 117 membrane. Considering these good properties and its low cost, SPEEK/PVDF/PES membrane is expected to have excellent commercial prospects as an ion exchange membrane for VRB systems.

Non-Platinum Group Metal OER/ORR Catalysts for Alkaline Membrane Fuel Cells and Electrolyzers

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

Danilovic, Nemanja; Ayers, Katherine

Regenerative fuel cells (RFC) are energy storage devices that capture electrical energy in the form of hydrogen, with potential application for backup power and energy storage in remote locations, unmanned missions, and renewable energy capture. A unitized regenerative fuel cell (URFC) combines two separate electrochemical devices (fuel cell and electrolyzer) into one stack. The stack cost is driven by the platinum group metal (PGM) catalysts and the flow field components designed to withstand high potentials in acidic environments. Since the stack is the most expensive subcomponent of both the fuel cell and electrolyzer system, combining the two devices results inmore » substantial reduction in capital cost. However, in the past, combining the two stacks sacrificed device performance (operating cost) largely because the fuel cell had to operate with the thick electrolysis membranes in a URFC configuration, and due to water management issues in switching modes. Recent work in membrane-based electrolysis has resulted in more mechanically robust designs and materials that allow much thinner membranes, and work in flow cell design such as flow batteries has shown improved water transport through channel design and wet-proofing approaches. Therefore, the URFC concept is worth revisiting. At the same time, alkaline exchange membrane (AEM) devices are gathering attention due to the promise of PGM and valve metal elimination from the stack and a resulting strategic and capital cost benefit as compared with proton exchange membrane (PEM) systems. The result is a lower capital cost system that has half the precious metal group (PGM) catalysts, membrane and other stack component materials compared with discrete RFCs, although at the sacrifice of performance (operating cost). Proton has identified innovative AEM based RFC's to fulfill the role of low capital cost energy storage device owing to the use of non-precious metal containing electrodes, that enables certain markets

Hydroxide Solvation and Transport in Anion Exchange Membranes.

PubMed

Chen, Chen; Tse, Ying-Lung Steve; Lindberg, Gerrick E; Knight, Chris; Voth, Gregory A

2016-01-27

Understanding hydroxide solvation and transport in anion exchange membranes (AEMs) can provide important insight into the design principles of these new membranes. To accurately model hydroxide solvation and transport, we developed a new multiscale reactive molecular dynamics model for hydroxide in aqueous solution, which was then subsequently modified for an AEM material. With this model, we investigated the hydroxide solvation structure and transport mechanism in the membrane. We found that a relatively even separation of the rigid side chains produces a continuous overlapping region for hydroxide transport that is made up of the first hydration shell of the tethered cationic groups. Our results show that hydroxide has a significant preference for this overlapping region, transporting through it and between the AEM side chains with substantial contributions from both vehicular (standard diffusion) and Grotthuss (proton hopping) mechanisms. Comparison of the AEM with common proton exchange membranes (PEMs) showed that the excess charge is less delocalized in the AEM than the PEMs, which is correlated with a higher free energy barrier for proton transfer reactions. The vehicular mechanism also contributes considerably more than the Grotthuss mechanism for hydroxide transport in the AEM, while our previous studies of PEM systems showed a larger contribution from the Grotthuss mechanism than the vehicular mechanism for proton transport. The activation energy barrier for hydroxide diffusion in the AEM is greater than that for proton diffusion in PEMs, implying a more significant enhancement of ion transport in the AEM at elevated temperatures.

Hydrogen-oxygen proton-exchange membrane fuel cells and electrolyzers

NASA Technical Reports Server (NTRS)

Baldwin, R.; Pham, M.; Leonida, A.; Mcelroy, J.; Nalette, T.

1989-01-01

Hydrogen-oxygen solid polymer electrolyte (SPE) fuel cells and SPE electrolyzers (products of Hamilton Standard) both use a Proton-Exchange Membrane (PEM) as the sole electrolyte. These solid electrolyte devices have been under continuous development for over 30 years. This experience has resulted in a demonstrated ten-year SPE cell life capability under load conditions. Ultimate life of PEM fuel cells and electrolyzers is primarily related to the chemical stability of the membrane. For perfluorocarbon proton exchange membranes an accurate measure of the membrane stability is the fluoride loss rate. Millions of cell hours have contributed to establishing a relationship between fluoride loss rates and average expected ultimate cell life. This relationship is shown. Several features have been introduced into SPE fuel cells and SPE electrolyzers such that applications requiring greater than or equal to 100,000 hours of life can be considered. Equally important as the ultimate life is the voltage stability of hydrogen-oxygen fuel cells and electrolyzers. Here again the features of SPE fuel cells and SPE electrolyzers have shown a cell voltage stability in the order of 1 microvolt per hour. That level of stability has been demonstrated for tens of thousands of hours in SPE fuel cells at up to 500 amps per square foot (ASF) current density.

Synthesis and characterization of Nafion/TiO2 nanocomposite membrane for proton exchange membrane fuel cell.

PubMed

Kim, Tae Young; Cho, Sung Yong

2011-08-01

In this study, the syntheses and characterizations of Nafion/TiO2 membranes for a proton exchange membrane fuel cell (PEMFC) were investigated. Porous TiO2 powders were synthesized using the sol-gel method; with Nafion/TiO2 nanocomposite membranes prepared using the casting method. An X-ray diffraction analysis demonstrated that the synthesized TiO2 had an anatase structure. The specific surface areas of the TiO2 and Nafion/TiO2 nanocomposite membrane were found to be 115.97 and 33.91 m2/g using a nitrogen adsorption analyzer. The energy dispersive spectra analysis indicated that the TiO2 particles were uniformly distributed in the nanocomposite membrane. The membrane electrode assembly prepared from the Nafion/TiO2 nanocomposite membrane gave the best PEMFC performance compared to the Nafion/P-25 and Nafion membranes.

Highly durable direct hydrazine hydrate anion exchange membrane fuel cell

NASA Astrophysics Data System (ADS)

Sakamoto, Tomokazu; Serov, Alexey; Masuda, Teruyuki; Kamakura, Masaki; Yoshimoto, Koji; Omata, Takuya; Kishi, Hirofumi; Yamaguchi, Susumu; Hori, Akihiro; Horiuchi, Yousuke; Terada, Tomoaki; Artyushkova, Kateryna; Atanassov, Plamen; Tanaka, Hirohisa

2018-01-01

The factors influenced on degradation of direct hydrazine hydrate fuel cells (DHFCs) under operation conditions are analyzed by in situ soft X-ray radiography. A durability of DHFCs is significantly improved by multi-step reaction DHFCs (MSR-DHFCs) approach designed to decrease the crossover of liquid fuel. An open circuit voltage (OCV) as well as cell voltage at 5 mA cm-2 of MSR-DHFC construct with commercial anion exchange membrane (AEM) maintained for over of 3500 h at 60 °C. Furthermore, the commercial proton exchange membrane (PEM) is integrated into AEM of MSR-DHFCs resulting in stable power output of MSR-DHFCs for over than 2800 h at 80 °C.

A Vivens Ex Vivo Study on the Synergistic Effect of Electrolysis and Freezing on the Cell Nucleus.

PubMed

Lugnani, Franco; Zanconati, Fabrizio; Marcuzzo, Thomas; Bottin, Cristina; Mikus, Paul; Guenther, Enric; Klein, Nina; Rubinsky, Liel; Stehling, Michael K; Rubinsky, Boris

2015-01-01

Freezing-cryosurgery, and electrolysis-electrochemical therapy (EChT), are two important minimally invasive surgery tissue ablation technologies. Despite major advantages they also have some disadvantages. Cryosurgery cannot induce cell death at high subzero freezing temperatures and requires multiple freeze thaw cycles, while EChT requires high concentrations of electrolytic products-which makes it a lengthy procedure. Based on the observation that freezing increases the concentration of solutes (including products of electrolysis) in the frozen region and permeabilizes the cell membrane to these products, this study examines the hypothesis that there could be a synergistic effect between freezing and electrolysis in their use together for tissue ablation. Using an animal model we refer to as vivens ex vivo, which may be of value in reducing the use of animals for experiments, combined with a Hematoxylin stain of the nucleus, we show that there are clinically relevant protocols in which the cell nucleus appears intact when electrolysis and freezing are used separately but is affected by certain combinations of electrolysis and freezing.

Repeated use of ion-exchange resin membranes in calcareous soils

USGS Publications Warehouse

Sherrod, S.K.; Belnap, Jayne; Miller, M.E.

2003-01-01

This study compared the consistency of nutrient extraction among repeated cycles of ion-exchange resin membrane use. Two sandy calcareous soils and different equilibration temperatures were tested. No single nutrient retained consistent values from cycle to cycle in all treatments, although both soil source and temperature conferred some influence. It was concluded that the most conservative use of resin membranes is single-use.

Preparation and Characterization of an Alkaline Anion Exchange Membrane from Chlorinated Poly(propylene) Aminated with Branched Poly(ethyleneimine)

DTIC Science & Technology

2013-01-01

exchange resins and as membranes for water purification [1], Li–air batteries, and in polymer exchange membrane ( PEM ) fuel cells [2]. PEM Fuel cells show...SUBJECT TERMS Anion exchange membrane, Fuel Cell , Poly(ethyleneimine), Quaternary ammonium caton, Hydroxide Ashley M. Maes, Tara P. Pandey, Melissa...membrane Fuel cell Poly(ethyleneimine) Quaternary ammonium cation Hydroxide a b s t r a c t A new randomly crosslinked polymer is investigated

Fluorine substituted (Mn,Ir)O 2:F high performance solid solution oxygen evolution reaction electro-catalysts for PEM water electrolysis

DOE PAGES

Ghadge, Shrinath Dattatray; Patel, Prasad Prakash; Datta, Moni Kanchan; ...

2017-03-20

Identification and development of high performance with reduced overpotential (i.e. reduced operating electricity cost) oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane (PEM) based water electrolysis with ultra-low noble metal content (i.e. reduced materials cost) is of significant interest for economic hydrogen production, thus increasing the commercialization potential of PEM water electrolysis. Accordingly, a novel electrocatalyst should exhibit low overpotential, excellent electrochemical activity and durability superior to state of the art noble metal based electro-catalysts (e.g. Pt, IrO 2, RuO 2). Here in this paper, for the very first time to the best of our knowledge, exploiting first-principles theoreticalmore » calculations of the total energies and electronic structures, we have identified a reduced noble metal content fluorine doped solid solution of MnO 2 and IrO 2, denoted as (Mn 1-xIr x)O 2:F (x = 0.2, 0.3, 0.4), OER electrocatalyst system exhibiting lower overpotential and higher current density than the state of the art IrO 2 and other previously reported systems for PEM water electrolysis. The doped solid solution displays an excellent electrochemical performance with a lowest reported onset potential to date of ~1.35 V (vs. RHE), ~80 mV lower than that of IrO 2 (~1.43 V vs. RHE) and ~15 fold (x = 0.3 and 0.4) higher electrochemical activity compared to pure IrO 2. In addition, the system displays excellent long term electrochemical durability, similar to that of IrO 2 in harsh acidic OER operating conditions. Our study therefore demonstrates remarkable, ~60–80% reduction in noble metal content along with lower overpotential and excellent electrochemical performance clearly demonstrating the potential of the (Mn 1-xIr x)O 2:F system as an OER electro-catalyst for PEM water electrolysis.« less

Fluorine substituted (Mn,Ir)O 2:F high performance solid solution oxygen evolution reaction electro-catalysts for PEM water electrolysis

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

Ghadge, Shrinath Dattatray; Patel, Prasad Prakash; Datta, Moni Kanchan

Identification and development of high performance with reduced overpotential (i.e. reduced operating electricity cost) oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane (PEM) based water electrolysis with ultra-low noble metal content (i.e. reduced materials cost) is of significant interest for economic hydrogen production, thus increasing the commercialization potential of PEM water electrolysis. Accordingly, a novel electrocatalyst should exhibit low overpotential, excellent electrochemical activity and durability superior to state of the art noble metal based electro-catalysts (e.g. Pt, IrO 2, RuO 2). Here in this paper, for the very first time to the best of our knowledge, exploiting first-principles theoreticalmore » calculations of the total energies and electronic structures, we have identified a reduced noble metal content fluorine doped solid solution of MnO 2 and IrO 2, denoted as (Mn 1-xIr x)O 2:F (x = 0.2, 0.3, 0.4), OER electrocatalyst system exhibiting lower overpotential and higher current density than the state of the art IrO 2 and other previously reported systems for PEM water electrolysis. The doped solid solution displays an excellent electrochemical performance with a lowest reported onset potential to date of ~1.35 V (vs. RHE), ~80 mV lower than that of IrO 2 (~1.43 V vs. RHE) and ~15 fold (x = 0.3 and 0.4) higher electrochemical activity compared to pure IrO 2. In addition, the system displays excellent long term electrochemical durability, similar to that of IrO 2 in harsh acidic OER operating conditions. Our study therefore demonstrates remarkable, ~60–80% reduction in noble metal content along with lower overpotential and excellent electrochemical performance clearly demonstrating the potential of the (Mn 1-xIr x)O 2:F system as an OER electro-catalyst for PEM water electrolysis.« less

Nonhumidified High-Temperature Membranes Developed for Proton Exchange Membrane Fuel Cells

NASA Technical Reports Server (NTRS)

Kinder, James D.

2005-01-01

Fuel cells are being considered for a wide variety of aerospace applications. One of the most versatile types of fuel cells is the proton-exchange-membrane (PEM) fuel cell. PEM fuel cells can be easily scaled to meet the power and space requirements of a specific application. For example, small 100-W PEM fuel cells are being considered for personal power for extravehicular activity suit applications, whereas larger PEM fuel cells are being designed for primary power in airplanes and in uninhabited air vehicles. Typically, PEM fuel cells operate at temperatures up to 80 C. To increase the efficiency and power density of the fuel cell system, researchers are pursuing methods to extend the operating temperature of the PEM fuel cell to 180 C. The most widely used membranes in PEM fuel cells are Nafion 112 and Nafion 117--sulfonated perfluorinated polyethers that were developed by DuPont. In addition to their relatively high cost, the properties of these membranes limit their use in a PEM fuel cell to around 80 C. The proton conductivity of Nafion membranes significantly decreases above 80 C because the membrane dehydrates. The useful operating range of Nafion-based PEM fuel cells can be extended to over 100 C if ancillary equipment, such as compressors and humidifiers, is added to maintain moisture levels within the membrane. However, the addition of these components reduces the power density and increases the complexity of the fuel cell system.

High temperature polymers for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Einsla, Brian Russel

Novel proton exchange membranes (PEMs) were investigated that show potential for operating at higher temperatures in both direct methanol (DMFC) and H 2/air PEM fuel cells. The need for thermally stable polymers immediately suggests the possibility of heterocyclic polymers bearing appropriate ion conducting sites. Accordingly, monomers and random disulfonated poly(arylene ether) copolymers containing either naphthalimide, benzoxazole or benzimidazole moieties were synthesized via direct copolymerization. The ion exchange capacity (IEC) was varied by simply changing the ratio of disulfonated monomer to nonsulfonated monomer in the copolymerization step. Water uptake and proton conductivity of cast membranes increased with IEC. The water uptake of these heterocyclic copolymers was lower than that of comparable disulfonated poly(arylene ether) systems, which is a desirable improvement for PEMs. Membrane electrode assemblies were prepared and the initial fuel cell performance of the disulfonated polyimide and polybenzoxazole (PBO) copolymers was very promising at 80°C compared to the state-of-the-art PEM (NafionRTM); nevertheless these membranes became brittle under operating conditions. Several series of poly(arylene ether)s based on disodium-3,3'-disulfonate-4,4 '-dichlorodiphenylsulfone (S-DCDPS) and a benzimidazole-containing bisphenol were synthesized and afforded copolymers with enhanced stability. Selected properties of these membranes were compared to separately prepared miscible blends of disulfonated poly(arylene ether sulfone) copolymers and polybenzimidazole (PBI). Complexation of the sulfonic acid groups with the PBI structure reduced water swelling and proton conductivity. The enhanced proton conductivity of NafionRTM membranes has been proposed to be due to the aggregation of the highly acidic side-chain sulfonic acid sites to form ion channels. A series of side-chain sulfonated poly(arylene ether sulfone) copolymers based on methoxyhydroquinone was

Combined uranous nitrate production consisting of undivided electrolytic cell and divided electrolytic cell (Electrolysis → Electrolytic cell)

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

Yuan, Zhongwei; Yan, Taihong; Zheng, Weifang

2013-07-01

The electrochemical reduction of uranyl nitrate is a green, mild way to make uranous ions. Undivided electrolyzers whose maintenance is less but their conversion ratio and current efficiency are low, have been chosen. However, at the beginning of undivided electrolysis, high current efficiency can also be maintained. Divided electrolyzers' conversion ratio and current efficiency is much higher because the re-oxidation of uranous on anode is avoided, but their maintenance costs are more, because in radioactive environment the membrane has to be changed after several operations. In this paper, a combined method of uranous production is proposed which consists of 2more » stages: undivided electrolysis (early stage) and divided electrolysis (late stage) to benefit from the advantages of both electrolysis modes. The performance of the combined method was tested. The results show that in combined mode, after 200 min long electrolysis (80 min undivided electrolysis and 120 min divided electrolysis), U(IV) yield can achieve 92.3% (500 ml feed, U 199 g/l, 72 cm{sup 2} cathode, 120 mA/cm{sup 2}). Compared with divided mode, about 1/3 working time in divided electrolyzer is reduced to achieve the same U(IV) yield. If 120 min long undivided electrolysis was taken, more than 1/2 working time can be reduced in divided electrolyzer, which means that about half of the maintenance cost can also be reduced. (authors)« less

Hydroxide Solvation and Transport in Anion Exchange Membranes

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

Chen, Chen; Tse, Ying-Lung Steve; Lindberg, Gerrick E.

Understanding hydroxide solvation and transport in anion exchange membranes (AEMs) can provide important insight into the design principles of these new membranes. To accurately model hydroxide solvation and transport, we developed a new multiscale reactive molecular dynamics model for hydroxide in aqueous solution, which was then subsequently modified for an AEM material. With this model, we investigated the hydroxide solvation structure and transport mechanism in the membrane. We found that a relatively even separation of the rigid side chains produces a continuous overlapping region for hydroxide transport that is made up of the first hydration shell of the tethered cationicmore » groups. Our results show that hydroxide has a significant preference for this overlapping region, transporting through it and between the AEM side chains with substantial contributions from both vehicular (standard diffusion) and Grotthuss (proton hopping) mechanisms. Comparison of the AEM with common proton exchange membranes (PEMs) showed that the excess charge is less delocalized in the AEM than the PEMs, which is correlated with a higher free energy barrier for proton transfer reactions. The vehicular mechanism also contributes considerably more than the Grotthuss mechanism for hydroxide transport in the AEM, while our previous studies of PEM systems showed a larger contribution from the Grotthuss mechanism than the vehicular mechanism for proton transport. The activation energy barrier for hydroxide diffusion in the AEM is greater than that for proton diffusion in PEMs, implying a more significant enhancement of ion transport in the AEM at elevated temperatures.« less

PEM Electrolyzer Incorporating an Advanced Low-Cost Membrane

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

Hamdan, Monjid

The Department of Energy (DOE) has identified hydrogen production by electrolysis of water at forecourt stations as a critical technology for transition to the hydrogen economy; however, the cost of hydrogen produced by present commercially available electrolysis systems is considerably higher than the DOE 2015 and 2020 cost targets. Analyses of proton-exchange membrane (PEM) electrolyzer systems indicate that reductions in electricity consumption and electrolyzer stack and system capital cost are required to meet the DOE cost targets. The primary objective is to develop and demonstrate a cost-effective energy-based system for electrolytic generation of hydrogen. The goal is to increase PEMmore » electrolyzer efficiency and to reduce electrolyzer stack and system capital cost to meet the DOE cost targets for distributed electrolysis. To accomplish this objective, work was conducted by a team consisting of Giner, Inc. (Giner), Virginia Polytechnic Institute & University (VT), and domnick hunter group, a subsidiary of Parker Hannifin (Parker). The project focused on four (4) key areas: (1) development of a high-efficiency, high-strength membrane; (2) development of a long-life cell-separator; (3) scale-up of cell active area to 290 cm2 (from 160 cm²); and (4) development of a prototype commercial electrolyzer system. In each of the key stack development areas Giner and our team members conducted focused development in laboratory-scale hardware, with analytical support as necessary, followed by life-testing of the most promising candidate materials. Selected components were then scaled up and incorporated into low-cost scaled-up stack hardware. The project culminated in the fabrication and testing of a highly efficient electrolyzer system for production of 0.5 kg/hr hydrogen and validation of the stack and system in testing at the National Renewable Energy Laboratory (NREL).« less

Solid polymer electrolyte water electrolysis preprototype subsystem. [oxygen production for life support systems on space stations

NASA Technical Reports Server (NTRS)

1979-01-01

Hardware and controls developed for an electrolysis demonstration unit for use with the life sciences payload program and in NASA's regenerative life support evaluation program are described. Components discussed include: the electrolysis module; power conditioner; phase separator-pump and hydrogen differential regulator; pressure regulation of O2, He, and N2; air-cooled heat exchanger; water accumulator; fluid flow sight gage assembly; catalytic O2/H2 sensor; gas flow sensors; low voltage power supply; 100 Amp DC contactor assembly; and the water purifier design.

Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap through Combined Refining and Solid Oxide Membrane Electrolysis Processes

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

Xiaofei Guan; Peter A. Zink; Uday B. Pal

2012-01-01

Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5wt.% Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the magnesium content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapor. The solid oxide membrane (SOM) electrolysis process is employed in themore » refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium.« less

Ion exchange membrane textile bioreactor as a new alternative for drinking water denitrification.

PubMed

Berdous, Dalila; Akretche, Djamal-Eddine; Abderahmani, Ahmed; Berdous, Sakina; Meknaci, Rima

2014-06-01

This work enters in the optics of the denitrification of a polluted water by two membrane techniques, the Donnan dialysis (DD) and the ion exchange membrane bioreactor (IEMB), using a conventional barrier, composed by an anion exchange membrane (AEM), and a hybrid barrier, where the AEM is combined to an anion exchange textile (AET). The effects of the hydrodynamic factor and the nature of the carbon source on the transfer and the reduction of nitrate ions were studied. The study results obtained through the DD showed the effectiveness of the hybrid barrier in the recovery and concentration of nitrate ions. This was also recorded during denitrification by the hybrid process, called the ion exchange membrane textile bioreactor (IEMTB), with a significant reduction of nitrates, compared to IEMB, due to the efficiency of the Pseudomonas aeruginosa biofilm formed at the surface of the AET. Here, the permselectivity of the membrane and the good bioreduction of the pollutants are no longer major conditions to the better performance of the process. The application of IEMTB in the denitrification of groundwater, having a nitrate concentration of 96.67 ppm, shows a total reduction of nitrate ions without changing the quality of the water. Indeed, the analysis of the recovered water, or yet the treated water, shows the absence of the bacterium by-products and concentrations in the nitrates and nitrites which are, respectively, equal to 0.02±0.01 ppm, and inferiors to the detection limit (<0.02 ppm).

Performance Evaluations of Ion Exchanged Zeolite Membranes on Alumina Supports

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

Bhave, Ramesh R.; Jubin, Robert Thomas; Spencer, Barry B.

2017-08-27

This report describes the synthesis and evaluation of molecular sieve zeolite membranes to separate and concentrate tritiated water (HTO) from dilute HTO-bearing aqueous streams. In the first phase of this effort, several monovalent and divalent cation-exchanged silico alumino phosphate (SAPO-34) molecular sieve zeolite membranes were synthesized on disk supports and characterized with gas and vapor permeation measurements. In the second phase, Linde Type A (LTA) zeolite membranes were synthesized in disk and tubular supports. The pervaporation process performance was evaluated for the separation and concentration of tritiated water.

Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell Membranes

NASA Technical Reports Server (NTRS)

Narayan, Sri R.; Yen, Shiao-Ping S.; Reddy, Prakash V.; Nair, Nanditha

2012-01-01

Polymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrene-based quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells. Imidazolium salts are known to be electrochemically stable over wide potential ranges. By controlling the relative ratio of imidazolium groups in polystyrene-imidazolium salts, their physiochemical properties could be modulated. Alkaline anion exchange membranes based on polystyrene-imidazolium hydroxide materials have been developed. The first step was to synthesize the poly(styrene-co-(1-((4-vinyl)methyl)-3- methylimidazolium) chloride through a free-radical polymerization. Casting of this material followed by in situ treatment of the membranes with sodium hydroxide solutions provided the corresponding hydroxide salts. Various ratios of the monomers 4-chloromoethylvinylbenzine (CMVB) and vinylbenzine (VB) provided various compositions of the polymer. The preferred material, due to the relative ease of casting the film, and its relatively low hygroscopic nature, was a 2:1 ratio of CMVB to VB. Testing confirmed that at room temperature, the new membranes outperformed commercially available membranes by a large margin. With fuel cells now in use at NASA and in transportation, and with defense potential, any improvement to fuel cell efficiency is a significant development.

Thermally Cross-Linked Anion Exchange Membranes from Solvent Processable Isoprene Containing Ionomers

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

Tsai, Tsung-Han; Ertem, S. Piril; Maes, Ashley M.

2015-01-28

Random copolymers of isoprene and 4-vinylbenzyl chloride (VBCl) with varying compositions were synthesized via nitroxide-mediated polymerization. Subsequent quaternization afforded solvent processable and cross-linkable ionomers with a wide range of ion exchange capacities (IECs). Solution cast membranes were thermally cross-linked to form anion exchange membranes. Cross-linking was achieved by taking advantage of the unsaturations on the polyisoprene backbone, without added cross-linkers. A strong correlation was found between water uptake and ion conductivity of the membranes: conductivities of the membranes with IECs beyond a critical value were found to be constant related to their high water absorption. Environmentally controlled small-angle X-ray scatteringmore » experiments revealed a correlation between the average distance between ionic clusters and the ion conductivity, indicating that a well-connected network of ion clusters is necessary for efficient ion conduction and high ion conductivity.« less

Hydrogen exchange mass spectrometry of functional membrane-bound chemotaxis receptor complexes.

PubMed

Koshy, Seena S; Eyles, Stephen J; Weis, Robert M; Thompson, Lynmarie K

2013-12-10

The transmembrane signaling mechanism of bacterial chemotaxis receptors is thought to involve changes in receptor conformation and dynamics. The receptors function in ternary complexes with two other proteins, CheA and CheW, that form extended membrane-bound arrays. Previous studies have shown that attractant binding induces a small (∼2 Å) piston displacement of one helix of the periplasmic and transmembrane domains toward the cytoplasm, but it is not clear how this signal propagates through the cytoplasmic domain to control the kinase activity of the CheA bound at the membrane-distal tip, nearly 200 Å away. The cytoplasmic domain has been shown to be highly dynamic, which raises the question of how a small piston motion could propagate through a dynamic domain to control CheA kinase activity. To address this, we have developed a method for measuring dynamics of the receptor cytoplasmic fragment (CF) in functional complexes with CheA and CheW. Hydrogen-deuterium exchange mass spectrometry (HDX-MS) measurements of global exchange of the CF demonstrate that the CF exhibits significantly slower exchange in functional complexes than in solution. Because the exchange rates in functional complexes are comparable to those of other proteins with similar structures, the CF appears to be a well-structured protein within these complexes, which is compatible with its role in propagating a signal that appears to be a tiny conformational change in the periplasmic and transmembrane domains of the receptor. We also demonstrate the feasibility of this protocol for local exchange measurements by incorporating a pepsin digest step to produce peptides with 87% sequence coverage and only 20% back exchange. This method extends HDX-MS to membrane-bound functional complexes without detergents that may perturb the stability or structure of the system.

Hydrogen Exchange Mass Spectrometry of Functional Membrane-bound Chemotaxis Receptor Complexes

PubMed Central

Koshy, Seena S.; Eyles, Stephen J.; Weis, Robert M.; Thompson, Lynmarie K.

2014-01-01

The transmembrane signaling mechanism of bacterial chemotaxis receptors is thought to involve changes in receptor conformation and dynamics. The receptors function in ternary complexes with two other proteins, CheA and CheW, that form extended membrane-bound arrays. Previous studies have shown that attractant binding induces a small (~2 Å) piston displacement of one helix of the periplasmic and transmembrane domains towards the cytoplasm, but it is not clear how this signal propagates through the cytoplasmic domain to control the kinase activity of the CheA bound at the membrane-distal tip, nearly 200 Å away. The cytoplasmic domain has been shown to be highly dynamic, which raises the question of how a small piston motion could propagate through a dynamic domain to control CheA kinase activity. To address this, we have developed a method for measuring dynamics of the receptor cytoplasmic fragment (CF) in functional complexes with CheA and CheW. Hydrogen exchange mass spectrometry (HDX-MS) measurements of global exchange of CF demonstrate that CF exhibits significantly slower exchange in functional complexes than in solution. Since the exchange rates in functional complexes are comparable to that of other proteins of similar structure, the CF appears to be a well-structured protein within these complexes, which is compatible with its role in propagating a signal that appears to be a tiny conformational change in the periplasmic and transmembrane domains of the receptor. We also demonstrate the feasibility of this protocol for local exchange measurements, by incorporating a pepsin digest step to produce peptides with 87% sequence coverage and only 20% back exchange. This method extends HDX-MS to membrane-bound functional complexes without detergents that may perturb the stability or structure of the system. PMID:24274333

Coulometric sodium chloride removal system with Nafion membrane for seawater sample treatment.

PubMed

Grygolowicz-Pawlak, Ewa; Sohail, Manzar; Pawlak, Marcin; Neel, Bastien; Shvarev, Alexey; de Marco, Roland; Bakker, Eric

2012-07-17

Seawater analysis is one of the most challenging in the field of environmental monitoring, mainly due to disparate concentration levels between the analyte and the salt matrix causing interferences in a variety of analytical techniques. We propose here a miniature electrochemical sample pretreatment system for a rapid removal of NaCl utilizing the coaxial arrangement of an electrode and a tubular Nafion membrane. Upon electrolysis, chloride is deposited at the Ag electrode as AgCl and the sodium counterions are transported across the membrane. This cell was found to work efficiently at potentials higher than 400 mV in both stationary and flow injection mode. Substantial residual currents observed during electrolysis were found to be a result of NaCl back diffusion from the outer side of the membrane due to insufficient permselectivity of the Nafion membrane. It was demonstrated that the residual current can be significantly reduced by adjusting the concentration of the outer solution. On the basis of ion chromatography results, it was found that the designed cell used in flow injection electrolysis mode reduced the NaCl concentration from 0.6 M to 3 mM. This attempt is very important in view of nutrient analysis in seawater where NaCl is a major interfering agent. We demonstrate that the pretreatment of artificial seawater samples does not reduce the content of nitrite or nitrate ions upon electrolysis. A simple diffusion/extraction steady state model is proposed for the optimization of the electrolysis cell characteristics.

Uncertainties of Gaseous Oxidized Mercury Measurements Using KCl-Coated Denuders, Cation-Exchange Membranes, and Nylon Membranes: Humidity Influences.

PubMed

Huang, Jiaoyan; Gustin, Mae Sexauer

2015-05-19

Quantifying the concentration of gaseous oxidized mercury (GOM) and identifying the chemical compounds in the atmosphere are important for developing accurate local, regional, and global biogeochemical cycles. The major hypothesis driving this work was that relative humidity affects collection of GOM on KCl-coated denuders and nylon membranes, both currently being applied to measure GOM. Using a laboratory manifold system and ambient air, GOM capture efficiency on 3 different collection surfaces, including KCl-coated denuders, nylon membranes, and cation-exchange membranes, was investigated at relative humidity ranging from 25 to 75%. Recovery of permeated HgBr2 on KCl-coated denuders declined by 4-60% during spikes of relative humidity (25 to 75%). When spikes were turned off GOM recoveries returned to 60 ± 19% of permeated levels. In some cases, KCl-coated denuders were gradually passivated over time after additional humidity was applied. In this study, GOM recovery on nylon membranes decreased with high humidity and ozone concentrations. However, additional humidity enhanced GOM recovery on cation-exchange membranes. In addition, reduction and oxidation of elemental mercury during experiments was observed. The findings in this study can help to explain field observations in previous studies.

Anion exchange composite membrane based on octa quaternary ammonium Polyhedral Oligomeric Silsesquioxane for alkaline fuel cells

NASA Astrophysics Data System (ADS)

Elumalai, Vijayakumar; Sangeetha, Dharmalingam

2018-01-01

A series of novel composite anion exchange membranes were prepared via simple solution casting method using synthesized quaternary ammonium functionalized Polyhedral Oligomeric Silsesquioxane (QA-POSS) with Quaternary polysulfone (QPSU). QA-POSS was synthesized from prepared Cl-POSS and well characterized by FT-IR, NMR, SEM and TEM analyses to confirm the chemical modifications and cubic morphologies. The QA-POSS nano particles have dual role in the membrane providing additional ion conducting groups and reinforcing the membrane in molecular level for the overall improvement of composite membrane. Additionally, the composite membranes were characterized by XRD, SEM, Ion exchange capacity (IEC), water uptake and conductivity to ensure the suitability of its use as an electrolyte in alkaline fuel cell. Finally, membrane electrode assembly (MEA) was fabricated using Pt anode (0.25 mg/cm2), Ag cathode (0.375 mg/cm2) and various synthesized composite membranes, and then it was tested in real time fuel cell setup. The membrane with 15% QA-POSS showed the maximum power density of 321 mW/cm2. The results showed that QA-POSS possess the ability to enhance the performance of the anion exchange membrane significantly.

Enhancement of waste activated sludge anaerobic digestion by a novel chemical free acid/alkaline pretreatment using electrolysis.

PubMed

Charles, W; Ng, B; Cord-Ruwisch, R; Cheng, L; Ho, G; Kayaalp, A

2013-01-01

Anaerobic digestion of waste activated sludge (WAS) is relatively poor due to hydrolysis limitations. Acid and alkaline pretreatments are effective in enhancing hydrolysis leading to higher methane yields. However, chemical costs often prohibit full-scale application. In this study, 12 V two-chamber electrolysis using an anion exchange membrane alters sludge pH without chemical dosing. pH dropped from 6.9 to 2.5 in the anode chamber and increased to 10.1 in the cathode chamber within 15 h. The volatile suspended solids solubilisation of WAS was 31.1% in the anode chamber and 34.0% in the cathode chamber. As a result, dissolved chemical oxygen demand increased from 164 to 1,787 mg/L and 1,256 mg/L in the anode and cathode chambers, respectively. Remixing of sludge from the two chambers brought the pH back to 6.5, hence no chemical neutralisation was required prior to anaerobic digestion. Methane yield during anaerobic digestion at 20 d retention time was 31% higher than that of untreated sludge. An energy balance assessment indicated that the non-optimised process could approximately recover the energy (electricity) expended in the electrolysis process. With suitable optimisation of treatment time and voltages, significant energy savings would be expected in addition to the benefit of decreased sludge volume.

Electrically Conductive Porous Membrane

NASA Technical Reports Server (NTRS)

Burke, Kenneth Alan (Inventor)

2014-01-01

The present invention relates to an electrically conductive membrane that can be configured to be used in fuel cell systems to act as a hydrophilic water separator internal to the fuel cell, or as a water separator used with water vapor fed electrolysis cells, or as a water separator used with water vapor fed electrolysis cells, or as a capillary structure in a thin head pipe evaporator, or as a hydrophobic gas diffusion layer covering the fuel cell electrode surface in a fuel cell.

Membrane consisting of polyquaternary amine ion exchange polymer network interpenetrating the chains of thermoplastic matrix polymer

NASA Technical Reports Server (NTRS)

Rembaum, A.; Wallace, C. J. (Inventor)

1978-01-01

An ion exchange membrane was formed from a solution containing dissolved matrix polymer and a set of monomers which are capable of reacting to form a polyquaternary ion exchange material; for example vinyl pyride and a dihalo hydrocarbon. After casting solution and evaporation of the volatile component's, a relatively strong ion exchange membrane was obtained which is capable of removing anions, such as nitrate or chromate from water. The ion exchange polymer forms an interpenetrating network with the chains of the matrix polymer.

Mercury removal from water streams through the ion exchange membrane bioreactor concept.

PubMed

Oehmen, Adrian; Vergel, Dario; Fradinho, Joana; Reis, Maria A M; Crespo, João G; Velizarov, Svetlozar

2014-01-15

Mercury is a highly toxic heavy metal that causes human health problems and environmental contamination. In this study, an ion exchange membrane bioreactor (IEMB) process was developed to achieve Hg(II) removal from drinking water and industrial effluents. Hg(II) transport through a cation exchange membrane was coupled with its bioreduction to Hg(0) in order to achieve Hg removal from concentrated streams, with minimal production of contaminated by-products observed. This study involves (1) membrane selection, (2) demonstration of process effectiveness for removing Hg from drinking water to below the 1ppb recommended limit, and (3) process application for treatment of concentrated water streams, where >98% of the Hg was removed, and the throughput of contaminated water was optimised through membrane pre-treatment. The IEMB process represents a novel mercury treatment technology with minimal generation of contaminated waste, thereby reducing the overall environmental impact of the process. Copyright © 2013 Elsevier B.V. All rights reserved.

Nano-Pervaporation Membrane with Heat Exchanger Generates Medical-Grade Water

NASA Technical Reports Server (NTRS)

Tsai, Chung-Yi; Alexander, Jerry

2009-01-01

A nanoporous membrane is used for the pervaporation process in which potable water is maintained, at atmospheric pressure, on the feed side of the membrane. The water enters the non-pervaporation (NPV) membrane device where it is separated into two streams -- retentate water and permeated water. The permeated pure water is removed by applying low vapor pressure on the permeate side to create water vapor before condensation. This permeated water vapor is subsequently condensed by coming in contact with the cool surface of a heat exchanger with heat being recovered through transfer to the feed water stream.

Electrolysis Propulsion for Spacecraft Applications

NASA Technical Reports Server (NTRS)

deGroot, Wim A.; Arrington, Lynn A.; McElroy, James F.; Mitlitsky, Fred; Weisberg, Andrew H.; Carter, Preston H., II; Myers, Blake; Reed, Brian D.

1997-01-01

Electrolysis propulsion has been recognized over the last several decades as a viable option to meet many satellite and spacecraft propulsion requirements. This technology, however, was never used for in-space missions. In the same time frame, water based fuel cells have flown in a number of missions. These systems have many components similar to electrolysis propulsion systems. Recent advances in component technology include: lightweight tankage, water vapor feed electrolysis, fuel cell technology, and thrust chamber materials for propulsion. Taken together, these developments make propulsion and/or power using electrolysis/fuel cell technology very attractive as separate or integrated systems. A water electrolysis propulsion testbed was constructed and tested in a joint NASA/Hamilton Standard/Lawrence Livermore National Laboratories program to demonstrate these technology developments for propulsion. The results from these testbed experiments using a I-N thruster are presented. A concept to integrate a propulsion system and a fuel cell system into a unitized spacecraft propulsion and power system is outlined.

Anodes for alkaline electrolysis

DOEpatents

Soloveichik, Grigorii Lev [Latham, NY

2011-02-01

A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

Studying ion exchange in solution and at biological membranes by FCS.

PubMed

Widengren, Jerker

2013-01-01

By FCS, a wide range of processes can be studied, covering time ranges from subnanoseconds to seconds. In principle, any process at equilibrium conditions can be measured, which reflects itself by a change in the detected fluorescence intensity. In this review, it is described how FCS and variants thereof can be used to monitor ion exchange, in solution and along biological membranes. Analyzing fluorescence fluctuations of ion-sensitive fluorophores by FCS offers selective advantages over other techniques for measuring local ion concentrations, and, in particular, for studying exchange kinetics of ions on a very local scale. This opens for several areas of application. The FCS approach was used to investigate fundamental aspects of proton exchange at and along biological membranes. The protonation relaxation rate, as measured by FCS for a pH-sensitive dye, can also provide information about local accessibility/interaction of a particular labeling site and conformational states of biomolecules, in a similar fashion as in a fluorescence quenching experiment. The same FCS concept can also be applied to ion exchange studies using other ion-sensitive fluorophores, and by use of dyes sensitive to other ambient conditions the concept can be extended also beyond ion exchange studies. Copyright © 2013 Elsevier Inc. All rights reserved.

Composite proton exchange membrane based on sulfonated organic nanoparticles

NASA Astrophysics Data System (ADS)

Pitia, Emmanuel Sokiri

As the world sets its sight into the future, energy remains a great challenge. Proton exchange membrane (PEM) fuel cell is part of the solution to the energy challenge because of its high efficiency and diverse application. The purpose of the PEM is to provide a path for proton transport and to prevent direct mixing of hydrogen and oxygen at the anode and the cathode, respectively. Hence, PEMs must have good proton conductivity, excellent chemical stability, and mechanical durability. The current state-of-the-art PEM is a perfluorosulfonate ionomer, Nafion®. Although Nafion® has many desirable properties, it has high methanol crossover and it is expensive. The objective of this research was to develop a cost effective two-phase, composite PEM wherein a dispersed conductive organic phase preferentially aligned in the transport direction controls proton transport, and a continuous hydrophobic phase provides mechanical durability to the PEM. The hypothesis that was driving this research was that one might expect better dispersion, higher surface to volume ratio and improved proton conductivity of a composite membrane if the dispersed particles were nanometer in size and had high ion exchange capacity (IEC, = [mmol sulfonic acid]/gram of polymer). In view of this, considerable efforts were employed in the synthesis of high IEC organic nanoparticles and fabrication of a composite membrane with controlled microstructure. High IEC, ~ 4.5 meq/g (in acid form, theoretical limit is 5.4 meq/g) nanoparticles were achieved by emulsion copolymerization of a quaternary alkyl ammonium (QAA) neutralized-sulfonated styrene (QAA-SS), styrene, and divinylbenzene (DVB). The effects of varying the counterion of the sulfonated styrene (SS) monomer (alkali metal and QAA cations), SS concentration, and the addition of a crosslinking agent (DVB) on the ability to stabilize the nanoparticles to higher IECs were assessed. The nanoparticles were ion exchanged to acid form. The extent of ion

Electrolysis Performance Improvement and Validation Experiment

NASA Technical Reports Server (NTRS)

Schubert, Franz H.

1992-01-01

Viewgraphs on electrolysis performance improvement and validation experiment are presented. Topics covered include: water electrolysis: an ever increasing need/role for space missions; static feed electrolysis (SFE) technology: a concept developed for space applications; experiment objectives: why test in microgravity environment; and experiment description: approach, hardware description, test sequence and schedule.

Selective permeation of moisture and VOCs through polymer membranes used in total heat exchangers for indoor air ventilation.

PubMed

Zhang, L-Z; Zhang, X-R; Miao, Q-Z; Pei, L-X

2012-08-01

Fresh air ventilation is central to indoor environmental control. Total heat exchangers can be key equipment for energy conservation in ventilation. Membranes have been used for total heat exchangers for more than a decade. Much effort has been spent to achieve water vapor permeability of various membranes; however, relatively little attention has been paid to the selectivity of moisture compared with volatile organic compounds (VOCs) through such membranes. In this investigation, the most commonly used membranes, both hydrophilic and hydrophobic ones, are tested for their permeability for moisture and five VOCs (acetic acid, formaldehyde, acetaldehyde, toluene, and ethane). The selectivity of moisture vs. VOCs in these membranes is then evaluated. With a solution-diffusion model, the solubility and diffusivity of moisture and VOCs in these membranes are calculated. The resulting data could provide some reference for future material selection. Total heat exchangers are important equipment for fresh air ventilation with energy conservation. However, their implications for indoor air quality in terms of volatile organic compound permeation have not been known. The data in this article help us to clarify the impacts on indoor VOC levels of membrane-based heat exchangers. Guidelines for material selection can be obtained for future use total heat exchangers for building ventilation. © 2011 John Wiley & Sons A/S.

Water uptake, ionic conductivity and swelling properties of anion-exchange membrane

NASA Astrophysics Data System (ADS)

Duan, Qiongjuan; Ge, Shanhai; Wang, Chao-Yang

2013-12-01

Water uptake, ionic conductivity and dimensional change of the anion-exchange membrane made by Tokuyama Corporation (A201 membrane) are investigated at different temperatures and water activities. Specifically, the amount of water taken up by membranes exposed to water vapor and membranes soaked in liquid water is determined. The water uptake of the A201 membrane increases with water content as well as temperature. In addition, water sorption data shows Schroeder's paradox for the AEMs investigated. The swelling properties of the A201 membrane exhibit improved dimensional stability compared with Nafion membrane. Water sorption of the A201 membrane occurs with a substantial negative excess volume of mixing. The threshold value of hydrophilic fraction in the A201 membrane for ionic conductivity is around 0.34, above which, the conductivity begins to rise quickly. This indicates that a change in the connectivity of the hydrophilic domains occurs when hydrophilic fraction approaches 0.34.

Photo-Cross-Linked Anion Exchange Membranes with Improved Water Management and Conductivity

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

Ertem, S. Piril; Tsai, Tsung-Han; Donahue, Melissa M.

Robust, cross-linked anion exchange membranes (AEMs) were prepared from solvent-processable polyisoprene- ran -poly(vinylbenzyltrimethylammonium chloride) (PI- ran -P- [VBTMA][Cl]) ionomers via photoinitiated thiol - ene chem- istry. Two series of membranes were prepared choosing two dithiol cross-linkers, 1,10-decanedithiol and 2,2 ' - (ethylenedioxy)diethanethiol, selected for their di ff erent hydro- phobicities. A strong correlation was found between the choice of dithiol cross-linker, water uptake, morphology, and the ion conductivity of the membranes. Results were compared with previous fi ndings of thermally cross-linked AEMs from analogous random copolymers. Comparably high chloride ion conductivities were obtained at low to moderate ion exchange capacitiesmore » (IECs) with signi fi cantly low water uptake values. It was shown that by choosing a hydrophilic cross-linker ion cluster formation may be suppressed and ion conduction improved. This study highlights that it is possible to promote ion conductivities for low IEC membranes (<1 mmol/g) by forming well- connected, ion conducting network morphology. This observation paves the way for mechanically robust ion conducting membranes with enhanced conductivities and better water management.« less

Steel reinforced composite silicone membranes and its integration to microfluidic oxygenators for high performance gas exchange.

PubMed

Matharoo, Harpreet; Dabaghi, Mohammadhossein; Rochow, Niels; Fusch, Gerhard; Saraei, Neda; Tauhiduzzaman, Mohammed; Veldhuis, Stephen; Brash, John; Fusch, Christoph; Selvaganapathy, P Ravi

2018-01-01

Respiratory distress syndrome (RDS) is one of the main causes of fatality in newborn infants, particularly in neonates with low birth-weight. Commercial extracorporeal oxygenators have been used for low-birth-weight neonates in neonatal intensive care units. However, these oxygenators require high blood volumes to prime. In the last decade, microfluidics oxygenators using enriched oxygen have been developed for this purpose. Some of these oxygenators use thin polydimethylsiloxane (PDMS) membranes to facilitate gas exchange between the blood flowing in the microchannels and the ambient air outside. However, PDMS is elastic and the thin membranes exhibit significant deformation and delamination under pressure which alters the architecture of the devices causing poor oxygenation or device failure. Therefore, an alternate membrane with high stability, low deformation under pressure, and high gas exchange was desired. In this paper, we present a novel composite membrane consisting of an ultra-thin stainless-steel mesh embedded in PDMS, designed specifically for a microfluidic single oxygenator unit (SOU). In comparison to homogeneous PDMS membranes, this composite membrane demonstrated high stability, low deformation under pressure, and high gas exchange. In addition, a new design for oxygenator with sloping profile and tapered inlet configuration has been introduced to achieve the same gas exchange at lower pressure drops. SOUs were tested by bovine blood to evaluate gas exchange properties. Among all tested SOUs, the flat design SOU with composite membrane has the highest oxygen exchange of 40.32 ml/min m 2 . The superior performance of the new device with composite membrane was demonstrated by constructing a lung assist device (LAD) with a low priming volume of 10 ml. The LAD was achieved by the oxygen uptake of 0.48-0.90 ml/min and the CO 2 release of 1.05-2.27 ml/min at blood flow rates ranging between 8 and 48 ml/min. This LAD was shown to increase the

Random and Block Sulfonated Polyaramides as Advanced Proton Exchange Membranes

DOE PAGES

Kinsinger, Corey L.; Liu, Yuan; Liu, Feilong; ...

2015-10-09

We present here the experimental and computational characterization of two novel copolyaramide proton exchange membranes (PEMs) with higher conductivity than Nafion at relatively high temperatures, good mechanical properties, high thermal stability, and the capability to operate in low humidity conditions. The random and block copolyaramide PEMs are found to possess different ion exchange capacities (IEC) in addition to subtle structural and morphological differences, which impact the stability and conductivity of the membranes. SAXS patterns indicate the ionomer peak for the dry block copolymer resides at q = 0.1 Å –1, which increases in amplitude when initially hydrated to 25% relativemore » humidity, but then decrease in amplitude with additional hydration. This pattern is hypothesized to signal the transport of water into the polymer matrix resulting in a reduced degree of phase separation. Coupled to these morphological changes, the enhanced proton transport characteristics and structural/mechanical stability for the block copolymer are hypothesized to be primarily due to the ordered structure of ionic clusters that create connected proton transport pathways while reducing swelling upon hydration. Interestingly, the random copolymer did not possess an ionomer peak at any of the hydration levels investigated, indicating a lack of any significant ionomer structure. The random copolymer also demonstrated higher proton conductivity than the block copolymer, which is opposite to the trend normally seen in polymer membranes. However, it has reduced structural/mechanical stability as compared to the block copolymer. In conclusion, this reduction in stability is due to the random morphology formed by entanglements of polymer chains and the adverse swelling characteristics upon hydration. Therefore, the block copolymer with its enhanced proton conductivity characteristics, as compared to Nafion, and favorable structural/mechanical stability, as compared to the

Theoretical investigation of local proton conductance in the proton exchange membranes

NASA Astrophysics Data System (ADS)

Singh, Raman K.; Tsuneda, Takao; Miyatake, Kenji; Watanabe, Masahiro

2014-07-01

The hydrated structures of the proton exchange membranes were theoretically investigated using long-range corrected density functional theory to make clear why perfluorinated polymer membrane Nafion is superior to other membranes in the proton conductivity at low humidity. For exploring the possibility of the proton conductance in the vehicle mechanism with low hydration numbers, we examined the relay model of protonated water clusters between the sulfonic acid groups in Nafion and concluded that this relay model may contribute to the high proton conductivity of Nafion with less-hydrated sulfonic acid groups.

Junction Potentials Bias Measurements of Ion Exchange Membrane Permselectivity.

PubMed

Kingsbury, Ryan S; Flotron, Sophie; Zhu, Shan; Call, Douglas F; Coronell, Orlando

2018-04-17

Ion exchange membranes (IEMs) are versatile materials relevant to a variety of water and waste treatment, energy production, and industrial separation processes. The defining characteristic of IEMs is their ability to selectively allow positive or negative ions to permeate, which is referred to as permselectivity. Measured values of permselectivity that equal unity (corresponding to a perfectly selective membrane) or exceed unity (theoretically impossible) have been reported for cation exchange membranes (CEMs). Such nonphysical results call into question our ability to correctly measure this crucial membrane property. Because weighing errors, temperature, and measurement uncertainty have been shown to not explain these anomalous permselectivity results, we hypothesized that a possible explanation are junction potentials that occur at the tips of reference electrodes. In this work, we tested this hypothesis by comparing permselectivity values obtained from bare Ag/AgCl wire electrodes (which have no junction) to values obtained from single-junction reference electrodes containing two different electrolytes. We show that permselectivity values obtained using reference electrodes with junctions were greater than unity for CEMs. In contrast, electrodes without junctions always produced permselectivities lower than unity. Electrodes with junctions also resulted in artificially low permselectivity values for AEMs compared to electrodes without junctions. Thus, we conclude that junctions in reference electrodes introduce two biases into results in the IEM literature: (i) permselectivity values larger than unity for CEMs and (ii) lower permselectivity values for AEMs compared to those for CEMs. These biases can be avoided by using electrodes without a junction.

A practical method for measuring the ion exchange capacity decrease of hydroxide exchange membranes during intrinsic degradation

NASA Astrophysics Data System (ADS)

Kreuer, Klaus-Dieter; Jannasch, Patric

2018-01-01

In this work we present a practical thermogravimetric method for quantifying the IEC (ion exchange capacity) decrease of hydroxide exchange membranes (HEMs) during intrinsic degradation mainly occurring through nucleophilic attack of the anion exchanging group by hydroxide ions. The method involves measuring weight changes under controlled temperature and relative humidity. These conditions are close to these in a fuel cell, i.e. the measured degradation rate includes all effects originating from the polymeric structure, the consumption of hydroxide ions and the release of water. In particular, this approach involves no added solvents or base, thereby avoiding inaccuracies that may arise in other methods due to the presence of solvents (other than water) or co-ions (such as Na+ or K+). We demonstrate the method by characterizing the decomposition of membranes consisting of poly(2,6-dimethyl-1,4-phenylene oxide) functionalized with trimethyl-pentyl-ammonium side chains. The decomposition rate is found to depend on temperature, relative humidity RH (controlling the hydration number λ) and the total water content (controlled by the actual IEC and RH).

Preparation and Characterization of Various Poly(ether ether ketone) Containing Imidazolium Moiety for Anion Exchange Membrane Fuel Cell Application.

PubMed

Lee, Byeol-Nim; Son, Tae Yang; Park, Chi Hoon; Kim, Tae Hyun; Nam, Sang Yong

2018-09-01

In this study, various poly(ether ether ketone) were synthesized using three different monomers and the imidazolium group was introduced into synthesized poly(ether ether ketone)s by using substitution reaction. Synthesized polymers were used to prepare anion exchange membranes and to evaluate its properties. Thermal, chemical and structural properties were carried out using thermogravimetric analysis, nuclear magnetic resonance. The anion exchange membranes with different imidazolium moieties were characterized by several different analytical techniques such as water up take, ion exchange capacity, hydroxide conductivity for checking the possibility to apply the anion exchange membrane fuel cell. Consequently, results of characterization were studied to understand the correlation between stabilities of the membrane and functional group and polymer backbone structures. And we confirm membrane performance was improved by increasing imidazolium cation groups.

A Vivens Ex Vivo Study on the Synergistic Effect of Electrolysis and Freezing on the Cell Nucleus

PubMed Central

Lugnani, Franco; Zanconati, Fabrizio; Marcuzzo, Thomas; Bottin, Cristina; Mikus, Paul; Guenther, Enric; Klein, Nina; Rubinsky, Liel; Stehling, Michael K.; Rubinsky, Boris

2015-01-01

Freezing—cryosurgery, and electrolysis—electrochemical therapy (EChT), are two important minimally invasive surgery tissue ablation technologies. Despite major advantages they also have some disadvantages. Cryosurgery cannot induce cell death at high subzero freezing temperatures and requires multiple freeze thaw cycles, while EChT requires high concentrations of electrolytic products—which makes it a lengthy procedure. Based on the observation that freezing increases the concentration of solutes (including products of electrolysis) in the frozen region and permeabilizes the cell membrane to these products, this study examines the hypothesis that there could be a synergistic effect between freezing and electrolysis in their use together for tissue ablation. Using an animal model we refer to as vivens ex vivo, which may be of value in reducing the use of animals for experiments, combined with a Hematoxylin stain of the nucleus, we show that there are clinically relevant protocols in which the cell nucleus appears intact when electrolysis and freezing are used separately but is affected by certain combinations of electrolysis and freezing. PMID:26695185

Separation of certain carboxylic acids utilizing cation exchange membranes

DOEpatents

Chum, H.L.; Sopher, D.W.

1983-05-09

A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100/sup 0/C and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

Separation of certain carboxylic acids utilizing cation exchange membranes

DOEpatents

Chum, Helena L.; Sopher, David W.

1984-01-01

A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100.degree. C. and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

Desulfurization from Bauxite Water Slurry (BWS) Electrolysis

NASA Astrophysics Data System (ADS)

Gong, Xuzhong; Ge, Lan; Wang, Zhi; Zhuang, Siyuan; Wang, Yuhua; Ren, Lihui; Wang, Mingyong

2016-02-01

Feasibility of high-sulfur bauxite electrolysis desulfurization was examined using the electrochemical characterization, XRD, DTA, and FTIR. The cyclic voltammetry curves indicated that bauxite water slurry (BWS) electrolysis in NaOH system was controlled by diffusion. Additionally, the desulfurization effect of NaCl as the electrolyte was significantly better than that of NaOH as an electrolyte. As the stirring rate increased, the desulfurization ratio in NaCl system was not increased obviously, while the desulfurization ratio in NaOH system increased significantly, indicating further that electrolysis desulfurization in NaOH solution was controlled by diffusion. According to XRD, DTA, and FTIR analysis, the characteristic peaks of sulfur-containing phase in bauxite after electrolysis weakened or disappeared, indicating that the pyrite in bauxite was removed from electrolysis. Finally, the electrolytic desulfurization technology of bauxite was proposed based on the characteristics of BWS electrolysis.

Study of the internal morphology of cation-exchange membranes by means of electroosmotic permeability relaxations.

PubMed

Barragán, V M; Izquierdo-Gil, M A; Godino, M P; Villaluenga, J P G

2009-10-01

The effect of an ac sinusoidal perturbation of known amplitude and frequency superimposed to the usual dc applied electric voltage difference on the electroosmotic flow through three cation-exchange membranes with different morphology has been studied. A dispersion of the electroosmotic permeability on the frequency of the applied ac signal has been found for the three membranes investigated, observing that the electroosmotic permeability reaches maximum values for some characteristic values of the frequency. These characteristic frequency values, which are related to relaxation processes in heterogeneous media, depend on the membrane system and permit to obtain information about the different structures of the membrane system. Thus, the study of the electroosmotic permeability relaxation can be used as a method to study the internal morphology of a cation-exchange membrane in a given electrolyte medium.

Anion exchange pathways for Cl sup minus transport in rabbit renal microvillus membranes

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

Karniski, L.P.; Aronson, P.S.

1987-09-01

The authors evaluated the mechanisms of chloride transport in microvillus membrane vesicles isolated from the rabbit renal cortex. The presence of Cl-formate exchange was confirmed. Outward gradients of oxaloacetate, HCO{sub 3}, acetate, lactate, succinate, sulfate, and p-aminohippurate (PAH) stimulated the rate of Cl uptake minimally or not at all. However, an outward gradient of oxalate stimulated Cl uptake by 70%, and an outward Cl gradient induced uphill oxalate uptake, indicting Cl-oxalate exchange. Moreover, an outward formate gradient induced uphill oxalate uptake, indicating formate-oxalate exchange. Studies of inhibitor and substrate specificity indicated the probably operation of at least two separate anionmore » exchangers in mediating Cl transport. The Cl-formate exchanger accepted Cl and formate as substrates, had little or no affinity for oxalate, was sensitive to inhibition by furosemide, and was less sensitive to inhibition by 4,4{prime}-diisothiocyanostilbene-2,2{prime}-disulfonic acid (DIDS). The Cl (formate)-oxalate exchanger also accepted Cl and formate as substrates but had high affinity for oxalate, was highly sensitive to inhibition by DIDS, and was less sensitive to inhibition by furosemide. The Cl-formate exchanger was electroneutral, whereas the Cl (formate)-oxalate exchanger was electrogenic. They conclude that at least separate anion exchangers mediating Cl transport are present on the luminal membrane of the rabbit proximal tubule cell. These exchangers may play important roles in mediating transtubular Cl and oxalate transport in this nephron segment.« less

Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap Through Combined Refining and Solid Oxide Membrane (SOM) Electrolysis Processes

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

Guan, Xiaofei; Zink, Peter; Pal, Uday

2012-03-11

Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5wt.%Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the Mg content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapors in a separate condenser. The solid oxide membrane (SOM) electrolysis process ismore » employed in the refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium; could not collect and weigh all of the magnesium recovered.« less

Importance of the REM (Ras exchange) domain for membrane interactions by RasGRP3.

PubMed

Czikora, Agnes; Kedei, Noemi; Kalish, Heather; Blumberg, Peter M

2017-12-01

RasGRP comprises a family of guanine nucleotide exchange factors, regulating the dissociation of GDP from Ras GTPases to enhance the formation of the active GTP-bound form. RasGRP1 possesses REM (Ras exchange), GEF (catalytic), EF-hand, C1, SuPT (suppressor of PT), and PT (plasma membrane-targeting) domains, among which the C1 domain drives membrane localization in response to diacylglycerol or phorbol ester and the PT domain recognizes phosphoinositides. The homologous family member RasGRP3 shows less plasma membrane localization. The objective of this study was to explore the role of the different domains of RasGRP3 in membrane translocation in response to phorbol esters. The full-length RasGRP3 shows limited translocation to the plasma membrane in response to PMA, even when the basic hydrophobic cluster in the PT domain, reported to be critical for RasGRP1 translocation to endogenous activators, is mutated to resemble that of RasGRP1. Moreover, exchange of the C-termini (SuPT-PT domain) of the two proteins had little effect on their plasma membrane translocation. On the other hand, while the C1 domain of RasGRP3 alone showed partial plasma membrane translocation, truncated RasGRP3 constructs, which contain the PT domain and are missing the REM, showed stronger translocation, indicating that the REM of RasGRP3 was a suppressor of its membrane interaction. The REM of RasGRP1 failed to show comparable suppression of RasGRP3 translocation. The marked differences between RasGRP3 and RasGRP1 in membrane interaction necessarily will contribute to their different behavior in cells and are relevant to the design of selective ligands as potential therapeutic agents. Published by Elsevier B.V.

Vanadium proton exchange membrane water electrolyser

NASA Astrophysics Data System (ADS)

Noack, Jens; Roznyatovskaya, Nataliya; Pinkwart, Karsten; Tübke, Jens

2017-05-01

In order to reverse the reactions of vanadium oxygen fuel cells and to regenerate vanadium redox flow battery electrolytes that have been oxidised by atmospheric oxygen, a vanadium proton exchange membrane water electrolyser was set up and investigated. Using an existing cell with a commercial and iridium-based catalyst coated membrane, it was possible to fully reduce V3.5+ and V3+ solutions to V2+ with the formation of oxygen and with coulomb efficiencies of over 96%. The cell achieved a maximum current density of 75 mA/cm2 during this process and was limited by the proximity of the V(III) reduction to the hydrogen evolution reaction. Due to the specific reaction mechanisms of V(IV) and V(III) ions, V(III) solutions were reduced with an energy efficiency of 61%, making this process nearly twice as energy efficient as the reduction of V(IV) to V(III). Polarisation curves and electrochemical impedance spectroscopy were used to further investigate the losses of half-cell reactions and to find ways of further increasing efficiency and performance levels.

Improved durability of proton exchange membrane fuel cells by introducing Sn (IV) oxide into electrodes using an ion exchange method

NASA Astrophysics Data System (ADS)

Poulsen, M. G.; Larsen, M. J.; Andersen, S. M.

2017-03-01

Electrodes of Proton Exchange Membrane Fuel Cells (PEMFCs), consisting of catalyst-coated gas diffusion layers, were subjected to an optimized ion exchange procedure, in which tin (IV) oxide (SnO2) nanoparticles were introduced into them. Both methanol and sulfuric acid were tested as ion exchange solvents. SnO2 has previously been shown to exhibit radical scavenging abilities towards radicals inside the electrocatalyst layers. Its presence inside the electrodes was confirmed using X-ray photoelectron spectroscopy and X-ray fluorescence. After exposure to an accelerated stress test in a three-electrode setup, the electrodes containing SnO2 were found to have retained approximately 73.0% of their original Pt, while only 53.2% was retained in electrodes treated identically, but without Sn. Similarly, the SnO2-treated electrodes also experienced a smaller loss in electrochemical surface area in comparison to before the accelerated stress test. A membrane electrode assembly (MEA) constructed with a SnO2-containing anode was evaluated over 500 h. The results showed remarkably reduced OCV decay rate and end of test hydrogen crossover compared to the control MEA, indicating that SnO2 aids in impeding membrane thinning and pinhole formation. The results point toward a positive effect of SnO2 on fuel cell durability, by reducing the degradation of the membrane as well as of the ionomer in the electrocatalyst layer.

CAPSTONE SENIOR DESIGN - SUPRAMOLECULAR PROTON EXCHANGE MEMBRANES FOR FUEL CELLS

EPA Science Inventory

In order to assume a leading role in the burgeoning hydrogen economy, new infrastructure will be required for fuel cell manufacturing and R&D capabilities. The objective of this proposal is the development of a new generation of advanced proton exchange membrane (PEM) technol...

Influence of the membrane ion exchange capacity on the catalyst layer of proton exchange membrane fuel cell

NASA Astrophysics Data System (ADS)

Navessin, Titichai

2005-07-01

This work investigated the effect of ion exchange capacity (IEC) of polymer electrolyte membranes (PEM) on the PEM fuel cell cathode catalyst layer. A series of radiation grafted ethylene tetrafluoroethylene-g-polystyrene sulfonic acid (ETFE-g-PSSA) membranes was used to provide a systematic variation of IEC. A method to fabricate gas diffusion electrodes (GDEs) was adapted and custom-made GDEs with known compositions were prepared. Oxygen electrochemistry, mass transport properties, water absorption behaviour and proton conductivity were studied in relation to the IEC. Electrochemical characterization including cyclic voltammetry, electrochemical impedance spectroscopy and linear sweep voltammetry were employed. The agglomerate model for cathodes was adapted and used to extract mass transport parameters from experimental results. Prior to investigation in fuel cell systems, studies were performed in a half-fuel cell, which simplified complicating parameters associated with fuel cell operation. It was found that membranes with higher IEC resulted in a higher active surface area of electrode. In contrast, they exhibited lower oxygen reduction performance. The extracted effective diffusion coefficient of oxygen and O2 solubility in the catalyst layer was used to estimate the extent of flooding, which revealed that ˜67--70% of void space was filled with water. The membrane's IEC regulates the extent of flooding of the cathode, which in turn affects its electrochemical characteristics. The investigation under operating fuel cell conditions revealed an increase in fuel cell performance with increasing IEC---a contradicting trend to that found for the half-fuel cell. This is explained by the interplay of electroosmotic flux and hydraulic counterflux in the membrane which affects water management in the membrane electrode assembly (MEA). The influence was most significant in the cathode catalyst layer, where it affects mass transport and electrochemical characteristics

Magnetic Resonance Imaging of Electrolysis.

PubMed Central

Meir, Arie; Hjouj, Mohammad; Rubinsky, Liel; Rubinsky, Boris

2015-01-01

This study explores the hypothesis that Magnetic Resonance Imaging (MRI) can image the process of electrolysis by detecting pH fronts. The study has relevance to real time control of cell ablation with electrolysis. To investigate the hypothesis we compare the following MR imaging sequences: T1 weighted, T2 weighted and Proton Density (PD), with optical images acquired using pH-sensitive dyes embedded in a physiological saline agar solution phantom treated with electrolysis and discrete measurements with a pH microprobe. We further demonstrate the biological relevance of our work using a bacterial E. Coli model, grown on the phantom. The results demonstrate the ability of MRI to image electrolysis produced pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E. Coli model grown on the phantom. The results are promising and invite further experimental research. PMID:25659942

Optimization of synthesis of the nickel-cobalt oxide based anode electrocatalyst and of the related membrane-electrode assembly for alkaline water electrolysis

NASA Astrophysics Data System (ADS)

Chanda, Debabrata; Hnát, Jaromir; Bystron, Tomas; Paidar, Martin; Bouzek, Karel

2017-04-01

In this work, the Ni-Co spinel oxides are synthesized via different methods and using different calcination temperatures. Properties of the prepared materials are compared. The best route is selected and used to prepare a Ni1+xCo2-xO4 (-1 ≤ x ≤ 1) series of materials in order to investigate their catalytic activity towards the oxygen evolution reaction (OER). The results show that hydroxide preparation yields NiCo2O4 oxide with the highest activity. 325 °C is identified as the optimum calcination temperature. Subsequently, the catalysts are tested in an electrolysis cell. To prepare an anode catalyst layer based on NiCo2O4 catalyst on top of a nickel foam substrate for membrane electrode assembly (MEA) construction, following polymer binders are used: anion-selective quaternized polyphenylene oxide (qPPO), inert polytetrafluoroethylene (PTFE®), and cation-selective Nafion®. qPPO ionomer containing MEA exhibited highest OER activity. The current density obtained using a MEA containing qPPO binder attains a value of 135 mA cm-2 at a cell voltage of 1.85 V. After 7 h chronopotentiometric experiment at a constant current density of 225 mA cm-2, the MEA employing PTFE® binder shows higher stability than the other binders in alkaline water electrolysis at 50 °C. Under similar conditions, stability of the PTFE®-binding MEA is examined for 135 h.

21 CFR 886.4250 - Ophthalmic electrolysis unit.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic electrolysis unit. 886.4250 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4250 Ophthalmic electrolysis unit. (a) Identification. An ophthalmic electrolysis unit is an AC-powered or battery-powered device intended to destroy...

21 CFR 886.4250 - Ophthalmic electrolysis unit.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic electrolysis unit. 886.4250 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4250 Ophthalmic electrolysis unit. (a) Identification. An ophthalmic electrolysis unit is an AC-powered or battery-powered device intended to destroy...

21 CFR 886.4250 - Ophthalmic electrolysis unit.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic electrolysis unit. 886.4250 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4250 Ophthalmic electrolysis unit. (a) Identification. An ophthalmic electrolysis unit is an AC-powered or battery-powered device intended to destroy...

21 CFR 886.4250 - Ophthalmic electrolysis unit.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic electrolysis unit. 886.4250 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4250 Ophthalmic electrolysis unit. (a) Identification. An ophthalmic electrolysis unit is an AC-powered or battery-powered device intended to destroy...

21 CFR 886.4250 - Ophthalmic electrolysis unit.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic electrolysis unit. 886.4250 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4250 Ophthalmic electrolysis unit. (a) Identification. An ophthalmic electrolysis unit is an AC-powered or battery-powered device intended to destroy...

A study on the electrolysis of sulfur dioxide and water for the sulfur cycle hydrogen production process

NASA Technical Reports Server (NTRS)

1980-01-01

Experimental electrolysis cells using various platinum catalyzed carbon electrodes were tested. When operated at 200 mA/sq cm current density using 50 w/o acid at 50 C and 1 atm, a reference cell required 1.22 volts and degraded rapidly. After several improvements were incorporated into electrodes and the test cell configuration, a later cell required only 0.77 volts under identical operating conditions. At a lower current density, 100 mA/sq cm, the cell required only 0.63 volts. Kinetic studies on metal electrodes, measurements of temperature effects on electrode kinetics, investigations of electrocatalytic activities of metal electrodes over a wide range of acid concentrations, cyclic voltametric studies and evaluation of alternate catalysts were also conducted. From diffusivity experiments, a cation exchange membrane material, P-4010, exhibited an excellent diffusion coefficient, more than two orders of magnitude lower than that of rubber. Ionic resistivity measurements of eight materials showed that microporous rubber had the lowest resistivity.

Bifunctional Crosslinking Agents Enhance Anion Exchange Membrane Efficacy for Vanadium Redox Flow Batteries.

PubMed

Wang, Wenpin; Xu, Min; Wang, Shubo; Xie, Xiaofeng; Lv, Yafei; Ramani, Vijay K

2014-06-02

A series of cross-linked fluorinated poly (aryl ether oxadiazole) membranes (FPAEOM) derivatized with imidazolium groups were prepared. Poly (N-vinylimidazole) (PVI) was used as the bifunctional cross-linking agent to: a) lower vanadium permeability, b) enhance dimensional stability, and c) concomitantly provide added ion exchange capacity in the resultant anion exchange membranes. At a molar ratio of PVI to FPAEOM of 1.5, the resultant membrane (FPAEOM-1.5 PVI) had an ion exchange capacity of 2.2 meq g-1, a vanadium permeability of 6.8×10-7 cm2 min-1, a water uptake of 68 wt.%, and an ionic conductivity of 22.0 mS cm-1, all at 25°C. Single cells prepared with the FPAEOM-1.5 PVI membrane exhibited a higher coulombic efficiency (> 92%) and energy efficiency (> 86%) after 40 test cycles in vanadium redox flow battery. The imidazolium cation showed high chemical stability in highly acidic and oxidizing vanadium solution as opposed to poor stability in alkaline solutions. Based on our DFT studies, this was attributed to the lower HOMO energy (-7.265 eV) of the HSO4- ion (compared to the OH- ion; -5.496 eV) and the larger HOMO-LUMO energy gap (6.394 eV) of dimethylimidazolium bisulfate ([DMIM] [HSO4]) as compared to [DMIM] [OH] (5.387 eV).

Hydrogen-oxygen proton-exchange membrane fuel cells and electrolyzers

NASA Technical Reports Server (NTRS)

Baldwin, R.; Pham, M.; Leonida, A.; Mcelroy, J.; Nalette, T.

1989-01-01

Hydrogen-oxygen SPE fuel cells and SPE electrolyzers (products of Hamilton Standard) both use a Proton-Exchange Membrane (PEM) as the sole electrolyte. The SPE cells have demonstrated a ten year life capability under load conditions. Ultimate life of PEM fuel cells and electrolyzers is primarily related to the chemical stability of the membrane. For perfluorocarbon proton-exchange membranes an accurate measure of the membrane stability is the fluoride loss rate. Millions of cell hours have contributed to establishing a relationship between fluroride loss rates and average expected ultimate cell life. Several features were introduced into SPE fuel cells and SPE electrolyzers such that applications requiring greater than or equal to 100,000 hours of life can be considered. Equally important as the ultimate life is the voltage stability of hydrogen-oxygen fuel cells and electrolyzers. Here again the features of SPE fuel cells and SPE electrolyzers have shown a cell voltage stability in the order of 1 microvolt per hour. That level of stability were demonstrated for tens of thousands of hours in SPE fuel cells at up to 500 amps per square foot (ASF) current density. The SPE electrolyzers have demonstrated the same at 1000 ASF. Many future extraterrestrial applications for fuel cells require that they be self recharged. To translate the proven SPE cell life and stability into a highly reliable extraterrestrial electrical energy storage system, a simplification of supporting equipment is required. Static phase separation, static fluid transport and static thermal control will be most useful in producting required system reliability. Although some 200,000 SPE fuel cell hours were recorded in earth orbit with static fluid phase separation, no SPE electrolyzer has, as yet, operated in space.

Feasibility Analysis of Liquefying Oxygen Generated from Water Electrolysis Units on Lunar Surface

NASA Technical Reports Server (NTRS)

Jeng, Frank F.

2009-01-01

Concepts for liquefying oxygen (O2) generated from water electrolysis subsystems on the Lunar surface were explored. Concepts for O2 liquefaction units capable of generating 1.38 lb/hr (0.63 kg/hr) liquid oxygen (LOX) were developed. Heat and mass balance calculations for the liquefaction concepts were conducted. Stream properties, duties of radiators, heat exchangers and compressors for the selected concepts were calculated and compared.

Nanostructured Ion-Exchange Membranes for Fuel Cells: Recent Advances and Perspectives.

PubMed

He, Guangwei; Li, Zhen; Zhao, Jing; Wang, Shaofei; Wu, Hong; Guiver, Michael D; Jiang, Zhongyi

2015-09-23

Polymer-based materials with tunable nanoscale structures and associated microenvironments hold great promise as next-generation ion-exchange membranes (IEMs) for acid or alkaline fuel cells. Understanding the relationships between nanostructure, physical and chemical microenvironment, and ion-transport properties are critical to the rational design and development of IEMs. These matters are addressed here by discussing representative and important advances since 2011, with particular emphasis on aromatic-polymer-based nanostructured IEMs, which are broadly divided into nanostructured polymer membranes and nanostructured polymer-filler composite membranes. For each category of membrane, the core factors that influence the physical and chemical microenvironments of the ion nanochannels are summarized. In addition, a brief perspective on the possible future directions of nanostructured IEMs is presented. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Suppressing Shuttle Effect Using Janus Cation Exchange Membrane for High-Performance Lithium-Sulfur Battery Separator.

PubMed

Li, Zhen; Han, Yu; Wei, Junhua; Wang, Wenqiang; Cao, Tiantian; Xu, Shengming; Xu, Zhenghe

2017-12-27

Suppressing the shuttle effect of polysulfide ions to obtain high durability and good electrochemical performance is of great concern in the field of lithium-sulfur batteries. To address this issue, a Janus membrane consisting of an ultrathin dense layer and a robust microporous layer is fabricated using cation exchange resin. Different from the composite membranes made from polyolefin membranes, the multiple layers of the Janus membrane in this study are synchronously generated by one step, getting rid of the additional complex coating processes. Excellent overall performance is obtained by the cooperation of multiple factors. The excellent ionic selectivity of cation exchange resin renders a great suppression of the shuttle effect, endowing the lithium-sulfur battery with high Coulombic efficiency of 92.0-99.0% (LiNO 3 -free electrolyte). The ultrathin property of a dense layer renders a low ionic resistance, resulting in 60% higher discharge capacity over the entire C-rates (versus the control sample with Celgard 2400 membrane). The robust macroporous layer supports the ultrathin layer to achieve a free-standing property, ensuring the usability of the Janus membrane.

SISGR-Fundamental Experimental and Theoretical Studies on a Novel Family of Oxide Catalyst Supports for Water Electrolysis

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

Kumta, Prashant

2014-10-03

Identification and development of non-noble metal based electro-catalysts or electro-catalysts with significant reduction of expensive noble metal contents (E.g. IrO2, Pt) with comparable electrochemical performance as the standard noble metal/metal oxide for proton exchange membrane (PEM) based water electrolysis would constitute a major breakthrough in the generation of hydrogen by water electrolysis. Accomplishing such a system would not only result reduction of the overall capital costs of PEM based water electrolyzers, but also help attain the targeted hydrogen production cost [< $ 3.0 / gallon gasoline equivalent (gge)] comparable to conventional liquid fuels. In line with these goals, it wasmore » demonstrated that fluorine doped IrO2 thin films and nanostructured high surface area powders display remarkably higher electrochemical activity, and comparable durability as pure IrO2 electro-catalyst for the oxygen evolution reaction (OER) in PEM based water electrolysis. Furthermore, corrosion resistant SnO2 and NbO2 support has been doped with F and coupled with IrO2 or RuO2 for use as an OER electro-catalyst. A solid solution of SnO2:F or NbO2:F with only 20 - 30 mol.% IrO2 or RuO2 yielding a rutile structure in the form of thin films and bulk nanoparticles displays similar electrochemical activity and stability as pure IrO2/RuO2. This would lead to more than 70 mol.% reduction in the noble metal oxide content. Novel nanostructured ternary (Ir,Sn,Nb)O2 thin films of different compositions FUNDAMENTAL STUDY OF NANOSTRUCTURED ELECTRO-CATALYSTS WITH REDUCED NOBLE METAL CONTENT FOR PEM BASED WATER ELECTROLYSIS 4 have also been studied. It has been shown that (Ir0.40Sn0.30Nb0.30)O2 shows similar electrochemical activity and enhanced chemical robustness as compared to pure IrO2. F doping of the ternary (Ir,Sn,Nb)O2 catalyst helps in further decreasing the noble metal oxide content of the catalyst. As a result, these reduced noble metal oxide catalyst systems would

Express Electrolysis.

ERIC Educational Resources Information Center

Smithenry, Dennis; Gassman, Christopher; Goodridge, Brandon; Petersen, Tom

1998-01-01

Explains the process of student and teacher collaboration on a project to develop a faster electrolysis mechanism. Provides a good example of the problem-based approach to science instruction and curriculum. (DDR)

A sugar-template manufacturing method for microsystem ion-exchange membranes

NASA Astrophysics Data System (ADS)

Festarini, Rio V.; Pham, Minh-Hao; Liu, Xinyue; Barz, Dominik P. J.

2017-07-01

In this work, we report on a novel method for producing ion-exchange membranes that can be integrated directly into polydimethylsiloxane-based micro devices. Ionomers such as NafionTM, a copolymer with high conductivity and selectivity to small cations, are generally incompatible with common micro device materials due to the chemical inertness of the tetrafluoroethylene-based skeleton and the swelling in aqueous solutions. Hence, we introduce a microfabrication concept where we use consolidated sugar granules as a template to produce a porous polydimethylsiloxane scaffold. Ionomer and scaffold are combined to a composite membrane where the cohesion of these incompatible materials is of rather mechanical nature; i.e. the ionomer is physically entrapped in the scaffold. Electrochemical impedance spectroscopy measurements reveal the excellent membrane conductivity for the upper electrolyte concentrations tested in this work.

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.

Alkaline degradation studies of anion exchange polymers to enable new membrane designs

NASA Astrophysics Data System (ADS)

Nunez, Sean Andrew

Current performance targets for anion-exchange membrane (AEM) fuel cells call for greater than 95% alkaline stability for 5000 hours at temperatures up to 120 °C. Using this target temperature of 120 °C, an incisive 1H NMR-based alkaline degradation method to identify the degradation products of n-alkyl spacer tetraalkylammonium cations in various AEM polymers and small molecule analogs. Herein, the degradation mechanisms and rates of benzyltrimethylammonium-, n-alkyl interstitial spacer- and n-alkyl terminal pendant-cations are studied on several architectures. These findings demonstrate that benzyltrimethylammonium- and n-alkyl terminal pendant cations are more labile than an n-alkyl interstitial spacer cation and conclude that Hofmann elimination is not the predominant mechanism of alkaline degradation. Additionally, the alkaline stability of an n-alkyl interstitial spacer cation is enhanced when combined with an n-alkyl terminal pendant. Interestingly, at 120 °C, an inverse trend was found in the overall alkaline stability of AEM poly(styrene) and AEM poly(phenylene oxide) samples than was previously shown at 80 °C. Successive small molecule studies suggest that at 120 °C, an anion-induced 1,4-elimination degradation mechanism may be activated on styrenic AEM polymers bearing an acidic alpha-hydrogen. In addition, an ATR-FTIR based method was developed to assess the alkaline stability of solid membranes and any added resistance to degradation that may be due to differential solubilities and phase separation. To increase the stability of anion exchange membranes, Oshima magnesate--halogen exchange was demonstrated as a method for the synthesis of new anion exchange membranes that typically fail in the presence of organolithium or Grignard reagents alone. This new chemistry, applied to non-resinous polymers for the first time, proved effective for the n-akyl interstitial spacer functionalization of poly(phenylene oxide) and poly(styrene- co

Review of cell performance in anion exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Dekel, Dario R.

2018-01-01

Anion exchange membrane fuel cells (AEMFCs) have recently received increasing attention since in principle they allow for the use of non-precious metal catalysts, which dramatically reduces the cost per kilowatt of power in fuel cell devices. Until not long ago, the main barrier in the development of AEMFCs was the availability of highly conductive anion exchange membranes (AEMs); however, improvements on this front in the past decade show that newly developed AEMs have already reached high levels of conductivity, leading to satisfactory cell performance. In recent years, a growing number of research studies have reported AEMFC performance results. In the last three years, new records in performance were achieved. Most of the literature reporting cell performance is based on hydrogen-AEMFCs, although an increasing number of studies have also reported the use of fuels others than hydrogen - such as alcohols, non-alcohol C-based fuels, as well as N-based fuels. This article reviews the cell performance and performance stability achieved in AEMFCs through the years since the first reports in the early 2000s.

Anion exchange membrane fuel cells: Current status and remaining challenges

NASA Astrophysics Data System (ADS)

Gottesfeld, Shimshon; Dekel, Dario R.; Page, Miles; Bae, Chulsung; Yan, Yushan; Zelenay, Piotr; Kim, Yu Seung

2018-01-01

The anion exchange membrane fuel cell (AEMFC) is an attractive alternative to acidic proton exchange membrane fuel cells, which to date have required platinum-based catalysts, as well as acid-tolerant stack hardware. The AEMFC could use non-platinum-group metal catalysts and less expensive metal hardware thanks to the high pH of the electrolyte. Over the last decade, substantial progress has been made in improving the performance and durability of the AEMFC through the development of new materials and the optimization of system design and operation conditions. In this perspective article, we describe the current status of AEMFCs as having reached beginning of life performance very close to that of PEMFCs when using ultra-low loadings of Pt, while advancing towards operation on non-platinum-group metal catalysts alone. In the latter sections, we identify the remaining technical challenges, which require further research and development, focusing on the materials and operational factors that critically impact AEMFC performance and/or durability. These perspectives may provide useful insights for the development of next-generation of AEMFCs.

Anion exchange membrane fuel cells: Current status and remaining challenges

DOE PAGES

Gottesfeld, Shimshon; Dekel, Dario R.; Page, Miles; ...

2017-09-01

The anion exchange membrane fuel cell (AEMFC) is an attractive alternative to acidic proton exchange membrane fuel cells, which to date have required platinum-based catalysts, as well as acid-tolerant stack hardware. The AEMFC could use non-platinum-group metal catalysts and less expensive metal hardware thanks to the high pH of the electrolyte. Over the last decade, substantial progress has been made in improving the performance and durability of the AEMFC through the development of new materials and the optimization of system design and operation conditions. Here in this perspective article, we describe the current status of AEMFCs as having reached beginningmore » of life performance very close to that of PEMFCs when using ultra-low loadings of Pt, while advancing towards operation on non-platinum-group metal catalysts alone. In the latter sections, we identify the remaining technical challenges, which require further research and development, focusing on the materials and operational factors that critically impact AEMFC performance and/or durability. Finally, these perspectives may provide useful insights for the development of next-generation of AEMFCs.« less

Assessing the utility of bipolar membranes for use in photoelectrochemical water-splitting cells.

PubMed

Vargas-Barbosa, Nella M; Geise, Geoffrey M; Hickner, Michael A; Mallouk, Thomas E

2014-11-01

Membranes are important in water-splitting solar cells because they prevent crossover of hydrogen and oxygen. Here, bipolar membranes (BPMs) were tested as separators in water electrolysis cells. Steady-state membrane and solution resistances, electrode overpotentials, and pH gradients were measured at current densities relevant to solar photoelectrolysis. Under forward bias conditions, electrodialysis of phosphate buffer ions creates a pH gradient across a BPM. Under reverse bias, the BPM can maintain a constant buffer pH on both sides of the cell, but a large membrane potential develops. Thus, the BPM does not present a viable solution for electrolysis in buffered electrolytes. However, the membrane potential is minimized when the anode and cathode compartments of the cell contain strongly basic and acidic electrolytes, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Failure of the Nernst-Einstein equation to correlate electrical resistances and rates of ionic self-exchange across certain fixed charge membranes.

PubMed

Gottlieb, M H; Sollner, K

1968-05-01

The electrical resistances and rates of self-exchange of univalent critical ions across several types of collodion matrix membranes of high ionic selectivity were studied over a wide range of conditions. The relationship which was observed between these quantities with membranes of a certain type, namely those activated with poly-2-vinyl-N-methyl pyridinium bromide, cannot be explained on the basis of current concepts of the movement of ions across ion exchange membranes. Rates of self-exchange across these membranes were several times greater than those calculated from the electrical resistances of the membranes on the basis of an expression derived by the use of the Nernst-Einstein equation. The magnitude of the discrepancy was greatest at low concentrations of the ambient electrolyte solution and was independent of the species of both critical and noncritical ions. The data obtained with other types of collodion matrix membranes were, at least approximately, in agreement with the predictions based on the Nernst-Einstein equation. Self-exchange rates across the anion permeable protamine collodion membranes, and across the cation permeable polystyrene sulfonic acid collodion membranes, were about 20% less than those calculated from the electrical resistances. The direction and magnitude of these differences, also observed by other investigators, are qualitatively understood as an electroosmotic effect. With cation permeable membranes prepared by the oxidation of preformed collodion membranes, almost exact agreement was obtained between measured and calculated self-exchange rates; the cause of the apparent absence of an electroosmotic effect with these membranes is unknown.

Failure of the Nernst-Einstein Equation to Correlate Electrical Resistances and Rates of Ionic Self-Exchange across Certain Fixed Charge Membranes

PubMed Central

Gottlieb, Melvin H.; Sollner, Karl

1968-01-01

The electrical resistances and rates of self-exchange of univalent critical ions across several types of collodion matrix membranes of high ionic selectivity were studied over a wide range of conditions. The relationship which was observed between these quantities with membranes of a certain type, namely those activated with poly-2-vinyl-N-methyl pyridinium bromide, cannot be explained on the basis of current concepts of the movement of ions across ion exchange membranes. Rates of self-exchange across these membranes were several times greater than those calculated from the electrical resistances of the membranes on the basis of an expression derived by the use of the Nernst-Einstein equation. The magnitude of the discrepancy was greatest at low concentrations of the ambient electrolyte solution and was independent of the species of both critical and noncritical ions. The data obtained with other types of collodion matrix membranes were, at least approximately, in agreement with the predictions based on the Nernst-Einstein equation. Self-exchange rates across the anion permeable protamine collodion membranes, and across the cation permeable polystyrene sulfonic acid collodion membranes, were about 20% less than those calculated from the electrical resistances. The direction and magnitude of these differences, also observed by other investigators, are qualitatively understood as an electroosmotic effect. With cation permeable membranes prepared by the oxidation of preformed collodion membranes, almost exact agreement was obtained between measured and calculated self-exchange rates; the cause of the apparent absence of an electroosmotic effect with these membranes is unknown. PMID:5699793

Treatment of high salt oxidized modified starch waste water using micro-electrolysis, two-phase anaerobic aerobic and electrolysis for reuse

NASA Astrophysics Data System (ADS)

Yi, Xuenong; Wang, Yulin

2017-06-01

A combined process of micro-electrolysis, two-phase anaerobic, aerobic and electrolysis was investigated for the treatment of oxidized modified starch wastewater (OMSW). Optimum ranges for important operating variables were experimentally determined and the treated water was tested for reuse in the production process of corn starch. The optimum hydraulic retention time (HRT) of micro-electrolysis, methanation reactor, aerobic process and electrolysis process were 5, 24, 12 and 3 h, respectively. The addition of iron-carbon fillers to the acidification reactor was 200 mg/L while the best current density of electrolysis was 300 A/m2. The biodegradability was improved from 0.12 to 0.34 by micro-electrolysis. The whole treatment was found to be effective with removal of 96 % of the chemical oxygen demand (COD), 0.71 L/day of methane energy recovery. In addition, active chlorine production (15,720 mg/L) was obtained by electrolysis. The advantage of this hybrid process is that, through appropriate control of reaction conditions, effect from high concentration of salt on the treatment was avoided. Moreover, the process also produced the material needed in the production of oxidized starch while remaining emission-free and solved the problem of high process cost.

Poly(terphenylene) Anion Exchange Membranes: The Effect of Backbone Structure on Morphology and Membrane Property

DOE PAGES

Lee, Woo-Hyung; Park, Eun Joo; Han, Junyoung; ...

2017-05-05

A new design concept for ion-conducting polymers in anion exchange membranes (AEMs) fuel cells is proposed based on structural studies and conformational analysis of polymers and their effect on the properties of AEMs. Thermally, chemically, and mechanically stable terphenyl-based polymers with pendant quaternary ammonium alkyl groups were synthesized to investigate the effect of varying the arrangement of the polymer backbone and cation-tethered alkyl chains. The results demonstrate that the microstructure and morphology of these polymeric membranes significantly influence ion conductivity and fuel cell performance. Finally, the results of this study provide new insights that will guide the molecular design ofmore » polymer electrolyte materials to improve fuel cell performance.« less

Attenuated Allergenic Activity of Ovomucoid After Electrolysis

PubMed Central

Kido, Jun

2015-01-01

Ovomucoid (OMC) is the most prominent allergen causing hen's egg allergy, containing disulfide (S-S) bonds that may be responsible for its allergic action. As S-S bonds may be reduced during electrolysis, this study was undertaken to evaluate modulation of the allergic action of OMC after electrolysis. Electrolysis was carried out for 1% OMC containing 1% sodium chloride for 30 minutes with a voltage difference of 90 V, 0.23 A (30 mA/cm2). Protein assays, amino acid measurement, and mass spectrometry in untreated OMC and OMC on both the anode and cathode sides after electrolysis were performed. Moreover, 21 patients with IgE-mediated hen's egg allergy were evaluated by using the skin prick test (SPT) for untreated OMC and OMC after electrolysis. The allergic action of OMC was reduced after electrolysis on both the anode and cathode sides when evaluated by the SPT. The modifications of OMC on electrolysis caused the loss of 2 distinct peptide fragments (57E-63K and 123H-128R) as seen on matrix-associated laser desorption/ionization time-of-flight mass spectrometry. The total free SH groups in OMC were increased on the cathode side. Although the regions of S-S broken bonds were not determined in this study, the change in S-S bonds in OMC on both the anode and cathode sides may reduce the allergenic activity. PMID:26333707

Theory of the formation of the electric double layer at the ion exchange membrane-solution interface.

PubMed

Moya, A A

2015-02-21

This work aims to extend the study of the formation of the electric double layer at the interface defined by a solution and an ion-exchange membrane on the basis of the Nernst-Planck and Poisson equations, including different values of the counter-ion diffusion coefficient and the dielectric constant in the solution and membrane phases. The network simulation method is used to obtain the time evolution of the electric potential, the displacement electric vector, the electric charge density and the ionic concentrations at the interface between a binary electrolyte solution and a cation-exchange membrane with total co-ion exclusion. The numerical results for the temporal evolution of the interfacial electric potential and the surface electric charge are compared with analytical solutions derived in the limit of the shortest times by considering the Poisson equation for a simple cationic diffusion process. The steady-state results are justified from the Gouy-Chapman theory for the diffuse double layer in the limits of similar and high bathing ionic concentrations with respect to the fixed-charge concentration inside the membrane. Interesting new physical insights arise from the interpretation of the process of the formation of the electric double layer at the ion exchange membrane-solution interface on the basis of a membrane model with total co-ion exclusion.

Bias-Exchange Metadynamics Simulation of Membrane Permeation of 20 Amino Acids.

PubMed

Cao, Zanxia; Bian, Yunqiang; Hu, Guodong; Zhao, Liling; Kong, Zhenzhen; Yang, Yuedong; Wang, Jihua; Zhou, Yaoqi

2018-03-16

Thermodynamics of the permeation of amino acids from water to lipid bilayers is an important first step for understanding the mechanism of cell-permeating peptides and the thermodynamics of membrane protein structure and stability. In this work, we employed bias-exchange metadynamics simulations to simulate the membrane permeation of all 20 amino acids from water to the center of a dipalmitoylphosphatidylcholine (DPPC) membrane (consists of 256 lipids) by using both directional and torsion angles for conformational sampling. The overall accuracy for the free energy profiles obtained is supported by significant correlation coefficients (correlation coefficient at 0.5-0.6) between our results and previous experimental or computational studies. The free energy profiles indicated that (1) polar amino acids have larger free energy barriers than nonpolar amino acids; (2) negatively charged amino acids are the most difficult to enter into the membrane; and (3) conformational transitions for many amino acids during membrane crossing is the key for reduced free energy barriers. These results represent the first set of simulated free energy profiles of membrane crossing for all 20 amino acids.

New High-Temperature Membranes Developed for Proton Exchange Membrane Fuel Cells

NASA Technical Reports Server (NTRS)

Kinder, James D.

2004-01-01

Fuel cells are receiving a considerable amount of attention for potential use in a variety of areas, including the automotive industry, commercial power generation, and personal electronics. Research at the NASA Glenn Research Center has focused on the development of fuel cells for use in aerospace power systems for aircraft, unmanned air vehicles, and space transportation systems. These applications require fuel cells with higher power densities and better durability than what is required for nonaerospace uses. In addition, membrane cost is a concern for any fuel cell application. The most widely used membrane materials for proton exchange membrane (PEM) fuel cells are based on sulfonated perfluorinated polyethers, typically Nafion 117, Flemion, or Aciplex. However, these polymers are costly and do not function well at temperatures above 80 C. At higher temperatures, conventional membrane materials dry out and lose their ability to conduct protons, essential for the operation of the fuel cell. Increasing the operating temperature of PEM fuel cells from 80 to 120 C would significantly increase their power densities and enhance their durability by reducing the susceptibility of the electrode catalysts to carbon monoxide poisoning. Glenn's Polymers Branch has focused on developing new, low-cost membranes that can operate at these higher temperatures. A new series of organically modified siloxane (ORMOSIL) polymers were synthesized for use as membrane materials in a high-temperature PEM fuel cell. These polymers have an organic portion that can allow protons to transport through the polymer film and a cross-linked silica network that gives the polymers dimensional stability. These flexible xerogel polymer films are thermally stable, with decomposition onset as high as 380 C. Two types of proton-conducting ORMOSIL films have been produced: (1) NASA-A, which can coordinate many highly acid inorganic salts that facilitate proton conduction and (2) NASA-B, which has been

Surface-Tension Replica-Exchange Molecular Dynamics Method for Enhanced Sampling of Biological Membrane Systems.

PubMed

Mori, Takaharu; Jung, Jaewoon; Sugita, Yuji

2013-12-10

Conformational sampling is fundamentally important for simulating complex biomolecular systems. The generalized-ensemble algorithm, especially the temperature replica-exchange molecular dynamics method (T-REMD), is one of the most powerful methods to explore structures of biomolecules such as proteins, nucleic acids, carbohydrates, and also of lipid membranes. T-REMD simulations have focused on soluble proteins rather than membrane proteins or lipid bilayers, because explicit membranes do not keep their structural integrity at high temperature. Here, we propose a new generalized-ensemble algorithm for membrane systems, which we call the surface-tension REMD method. Each replica is simulated in the NPγT ensemble, and surface tensions in a pair of replicas are exchanged at certain intervals to enhance conformational sampling of the target membrane system. We test the method on two biological membrane systems: a fully hydrated DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine) lipid bilayer and a WALP23-POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) membrane system. During these simulations, a random walk in surface tension space is realized. Large-scale lateral deformation (shrinking and stretching) of the membranes takes place in all of the replicas without collapse of the lipid bilayer structure. There is accelerated lateral diffusion of DPPC lipid molecules compared with conventional MD simulation, and a much wider range of tilt angle of the WALP23 peptide is sampled due to large deformation of the POPC lipid bilayer and through peptide-lipid interactions. Our method could be applicable to a wide variety of biological membrane systems.

Radiation-grafted proton exchange membranes based on co-grafting from binary monomer mixtures into poly(ethylene-co-tetrafluoroethylene) (ETFE) film

NASA Astrophysics Data System (ADS)

Sohn, Joon-Yong; Sung, Hae-Jun; Song, Joo-Myung; Shin, Junhwa; Nho, Young-Chang

2012-08-01

In this study, proton exchange membranes (PEMs) based on a poly(ethylene-co-tetrafluoroethylene) (ETFE) film were synthesized through the graft copolymerization of styrene and VTMS (vinyltrimethoxysilane), or styrene and TMSPM (3-(trimethoxysilyl) propyl methacrylate) binary monomer systems using a simultaneous irradiation method. The prepared membranes with the similar degrees of grafting were investigated by measuring ion exchange capacity, proton conductivity, water uptake, chemical stability, and dimensional stability. The results indicate that the silane-crosslinked proton exchange membrane (PEM) has not only lower water uptake and dimensional change but also high proton conductivity at low humidity condition compared to non-crosslinked poly(ethylene-co-tetrafluoroethylene)-g-poly(styrene sulfonic acid) (ETFE-g-PSSA). Also, the chemical stability of silane-crosslinked fuel cell membranes was more improved than that of non-crosslinked fuel cell membrane.

Nanofiber Ion-Exchange Membranes for the Rapid Uptake and Recovery of Heavy Metals from Water

PubMed Central

Chitpong, Nithinart; Husson, Scott M.

2016-01-01

An evaluation of the performance of polyelectrolyte-modified nanofiber membranes was undertaken to determine their efficacy in the rapid uptake and recovery of heavy metals from impaired waters. The membranes were prepared by grafting poly(acrylic acid) (PAA) and poly(itaconic acid) (PIA) to cellulose nanofiber mats. Performance measurements quantified the dynamic ion-exchange capacity for cadmium (Cd), productivity, and recovery of Cd(II) from the membranes by regeneration. The dynamic binding capacities of Cd(II) on both types of nanofiber membrane were independent of the linear flow velocity, with a residence time of as low as 2 s. Analysis of breakthrough curves indicated that the mass flow rate increased rapidly at constant applied pressure after membranes approached equilibrium load capacity for Cd(II), apparently due to a collapse of the polymer chains on the membrane surface, leading to an increased porosity. This mechanism is supported by hydrodynamic radius (Rh) measurements for PAA and PIA obtained from dynamic light scattering, which show that Rh values decrease upon Cd(II) binding. Volumetric productivity was high for the nanofiber membranes, and reached 0.55 mg Cd/g/min. The use of ethylenediaminetetraacetic acid as regeneration reagent was effective in fully recovering Cd(II) from the membranes. Ion-exchange capacities were constant over five cycles of binding-regeneration. PMID:27999394

Nanofiber Ion-Exchange Membranes for the Rapid Uptake and Recovery of Heavy Metals from Water.

PubMed

Chitpong, Nithinart; Husson, Scott M

2016-12-20

An evaluation of the performance of polyelectrolyte-modified nanofiber membranes was undertaken to determine their efficacy in the rapid uptake and recovery of heavy metals from impaired waters. The membranes were prepared by grafting poly(acrylic acid) (PAA) and poly(itaconic acid) (PIA) to cellulose nanofiber mats. Performance measurements quantified the dynamic ion-exchange capacity for cadmium (Cd), productivity, and recovery of Cd(II) from the membranes by regeneration. The dynamic binding capacities of Cd(II) on both types of nanofiber membrane were independent of the linear flow velocity, with a residence time of as low as 2 s. Analysis of breakthrough curves indicated that the mass flow rate increased rapidly at constant applied pressure after membranes approached equilibrium load capacity for Cd(II), apparently due to a collapse of the polymer chains on the membrane surface, leading to an increased porosity. This mechanism is supported by hydrodynamic radius (R h ) measurements for PAA and PIA obtained from dynamic light scattering, which show that R h values decrease upon Cd(II) binding. Volumetric productivity was high for the nanofiber membranes, and reached 0.55 mg Cd/g/min. The use of ethylenediaminetetraacetic acid as regeneration reagent was effective in fully recovering Cd(II) from the membranes. Ion-exchange capacities were constant over five cycles of binding-regeneration.

Synthesis of Silver Embedded Poly(o-Anisidine) Molybdophosphate Nano Hybrid Cation-Exchanger Applicable for Membrane Electrode

PubMed Central

Khan, Anish; Khan, Aftab Aslam Parwaz; Asiri, Abdullah M.; Rub, Malik Abdul

2014-01-01

Poly(o-anisidine) molybdophosphate was expediently obtained by sol-gel mixing of Poly(o-anisidine) into the inorganic matrices of molybdophosphate, which was allowed to react with silver nitrate to the formation of poly(o-anisidine) molybdophosphate embedded silver nano composite. The composite was characterized by Fourier Transform Infrared Spectroscopy, X-ray powder diffraction, UV-Vis Spectrophotometry, Fluorescence Spectroscopy, Scanning Electron Microscopy/Energy-dispersive X-ray Spectroscopy and Thermogravimertic Analysis. Ion exchange capacity and distribution studies were carried out to understand the ion-exchange capabilities of the nano composite. On the basis of highest distribution studies, this nano composite cation exchanger was used as preparation of heavy metal ion selective membrane. Membrane was characterized for its performance as porosity and swelling later on was used for the preparation of membrane electrode for Hg(II), having better linear range, wide working pH range (2–4.5) with fast response in the real environment. PMID:24805257

The influence of iridium chemical oxidation state on the performance and durability of oxygen evolution catalysts in PEM electrolysis

NASA Astrophysics Data System (ADS)

Siracusano, S.; Baglio, V.; Grigoriev, S. A.; Merlo, L.; Fateev, V. N.; Aricò, A. S.

2017-10-01

Nanosized Ir-black (3 nm) and Ir-oxide (5 nm) oxygen evolution electrocatalysts showing high performance in polymer electrolyte membrane (PEM) water electrolysis based on Aquivion® short-side chain ionomer membrane are investigated to understand the role of the Ir oxidation state on the electrocatalytic activity and stability. Despite the smaller mean crystallite size, the Ir-black electrocatalyst shows significantly lower initial performance than the Ir-oxide. During operation at high current density, the Ir-black shows a decrease of cell potential with time whereas the Ir-oxide catalyst shows increasing cell potential resulting in a degradation rate of about 10 μV/h, approaching 1000 h. The unusual behaviour of the Ir-black results from the oxidation of metallic Ir to IrOx. The Ir-oxide catalyst shows instead a hydrated structure on the surface and a negative shift of about 0.5 eV for the Ir 4f binding energy after 1000 h electrolysis operation. This corresponds to the formation of a sub-stoichiometric Ir-oxide on the surface. These results indicate that a hydrated IrO2 with high oxidation state on the surface is favourable in decreasing the oxygen evolution overpotential. Modifications of the Ir chemical oxidation state during operation can affect significantly the catalytic activity and durability of the electrolysis system.

Full cell study of Diels Alder poly(phenylene) anion and cation exchange membranes in vanadium redox flow batteries

DOE PAGES

Pezeshki, Alan M.; Fujimoto, Cy; Sun, Che -Nan; ...

2015-11-14

In this paper, we report on the performance of Diels Alder poly(phenylene) membranes in vanadium redox flow batteries. The membranes were functionalized with quaternary ammonium groups to form an anion exchange membrane (QDAPP) and with sulfonic acid groups to form a cation exchange membrane (SDAPP). Both membrane classes showed similar conductivities in the battery environment, suggesting that the ion conduction mechanism in the material is not strongly affected by the moieties along the polymer backbone. The resistance to vanadium permeation in QDAPP was not improved relative to SDAPP, further suggesting that the polarity of the functional groups do not playmore » a significant role in the membrane materials tested. Both QDAPP and SDAPP outperformed Nafion membranes in cycling tests, with both achieving voltage efficiencies above 85% while maintaining 95% coulombic efficiency while at a current density of 200 mA/cm 2.« less

Crosslinked anion exchange membranes prepared from poly(phenylene oxide) (PPO) for non-aqueous redox flow batteries

NASA Astrophysics Data System (ADS)

Li, Yun; Sniekers, Jeroen; Malaquias, João C.; Van Goethem, Cedric; Binnemans, Koen; Fransaer, Jan; Vankelecom, Ivo F. J.

2018-02-01

A stable and eco-friendly anion-exchange membrane (AEM) was prepared and applied in a non-aqueous all-copper redox flow battery (RFB). The AEM was prepared via a simple procedure, leading to a cross-linked structure containing quaternary ammonium groups without involvement of harmful trimethylamine. A network was thus constructed which ensured both ion transport and solvent resistance. The ion exchange capacity (IEC) of the membrane was tuned from 0.49 to 1.03 meq g-1 by varying the content of the 4, 4‧-bipyridine crosslinking agent. The membrane showed a good anion conductivity and retention of copper ions. As a proof of principle, a RFB single cell with this crosslinked membrane yielded a coulombic efficiency of 89%, a voltage efficiency of 61% and an energy efficiency of 54% at 7.5 mA cm-2.

Poly(phenylene)-based anion exchange membrane

DOEpatents

Hibbs, Michael [Albuquerque, NM; Cornelius, Christopher J [Albuquerque, NM; Fujimoto, Cy H [Albuquerque, NM

2011-02-15

A poly(phenylene) compound of copolymers that can be prepared with either random or multiblock structures where a first polymer has a repeat unit with a structure of four sequentially connected phenyl rings with a total of 2 pendant phenyl groups and 4 pendant tolyl groups and the second polymer has a repeat unit with a structure of four sequentially connected phenyl rings with a total of 6 pendant phenyl groups. The second polymer has chemical groups attached to some of the pendant phenyl groups selected from CH.sub.3, CH.sub.2Br, and CH.sub.2N(CH.sub.3).sub.3Br groups. When at least one group is CH.sub.2N(CH.sub.3).sub.3Br, the material functions as an anion exchange membrane.

A direct ascorbate fuel cell with an anion exchange membrane

NASA Astrophysics Data System (ADS)

Muneeb, Omar; Do, Emily; Tran, Timothy; Boyd, Desiree; Huynh, Michelle; Ghosn, Gregory; Haan, John L.

2017-05-01

Ascorbic Acid (Vitamin C) is investigated as a renewable alternative fuel for alkaline direct liquid fuel cells (DLFCs). The environmentally- and biologically-friendly compound, L-ascorbic acid (AA) has been modeled and studied experimentally under acidic fuel cell conditions. In this work, we demonstrate that ascorbic acid is a more efficient fuel in alkaline media than in acidic media. An operating direct ascorbate fuel cell is constructed with the combination of L-ascorbic acid and KOH as the anode fuel, air or oxygen as the oxidant, a polymer anion exchange membrane, metal or carbon black anode materials and metal cathode catalyst. Operation of the fuel cell at 60 °C using 1 M AA and 1 M KOH as the anode fuel and electrolyte, respectively, and oxygen gas at the cathode, produces a maximum power density of 73 mW cm-2, maximum current density of 497 mA cm-2 and an open circuit voltage of 0.90 V. This performance is significantly greater than that of an ascorbic acid fuel cell with a cation exchange membrane, and it is competitive with alkaline DLFCs fueled by alcohols.

Diels Alder polyphenylene anion exchange membrane for nonaqueous redox flow batteries

DOE PAGES

Small, Leo J.; Pratt, III, Harry D.; Fujimoto, Cy H.; ...

2015-10-23

Here highly conductive, solvent-resistant anionic Diels Alder polyphenylene (DAPP) membranes were synthesized with three different ionic contents and tested in an ionic liquid-based nonaqueous redox flow battery (RFB). These membranes display 3–10× increase in conductivity in propylene carbonate compared to some commercially available (aqueous) anion exchange membranes. The membrane with an ion content of 1.5 meq/g (DAPP1.5) proved too brittle for operation in a RFB, while the membrane with an ion content of 2.5 meq/g (DAPP2.5) allowed excessive movement of solvent and poor electrochemical yields (capacity fade). Despite having lower voltage efficiencies compared to DAPP2.5, the membrane with an intermediatemore » ion content of 2.0 meq/g (DAPP2.0) exhibited higher coulombic efficiencies (96.4% vs. 89.1%) and electrochemical yields (21.6% vs. 10.9%) after 50 cycles. Crossover of the electroactive species was the primary reason for decreased electrochemical yields. Analysis of the anolyte and catholyte revealed degradation of the electroactive species and formation of a film at the membrane-solution interface. Increases in membrane resistance were attributed to mechanical and thermal aging of the membrane; no chemical change was observed. As a result, improvements in the ionic selectivity and ionic conductivity of the membrane will increase the electrochemical yield and voltage efficiency of future nonaqueous redox flow batteries.« less

Direct measurement of concentration distribution within the boundary layer of an ion-exchange membrane.

PubMed

Choi, Jae-Hwan; Park, Jin-Soo; Moon, Seung-Hyeon

2002-07-15

In this study the concentration distributions within the diffusion boundary layer were obtained by directly measuring the potential drops while the currents (under- and overlimiting) passed through the Neosepta CMX cation-exchange membrane (Tokuyama Corp., Japan). Potential drops according to the distance from the membrane surface on the depleted side were measured using a microelectrode to obtain the concentration profile. From the concentration profiles obtained, it was observed that the diffusion boundary layers existed in the range of 300-350 microm, which reasonably coincide with the theoretical diffusion boundary layer thickness calculated from the limiting current density. Although there were some deviations between the concentrations determined from the Nernst model and those from experiments, it was confirmed that the Nernst model effectively depicts the transport phenomena in the ion-exchange membrane system. In addition it was found that the salt concentration at the membrane surface increased when the currents applied exceeded the limiting current. It is thought that the concentration polarization formed in the diffusion boundary layer at currents near or lower than the limiting current was disturbed by a turbulent convection when the current was greater than the limiting current. As a consequence, the concentration at the membrane surface increased to a sufficient level for generation of the overlimiting current.

Analysis of a membrane-based condesate recovery heat exchanger (CRX)

NASA Technical Reports Server (NTRS)

Newbold, D.D.

1993-01-01

The development of a temperature and humidity control system that can remove heat and recover water vapor is key to the development of an Environmental Control and Life Support System (ECLSS). Large quantities of water vapor must be removed from air, and this operation has proven difficult in the absense of gravity. This paper presents the modeling results from a program to develop a novel membrane-based heat exchanger known as the condensate recovery heat exchanger (CRX). This device cools and dehumidifies humid air and simultaneously recovers water-vapor condensate. In this paper, the CRX is described and the results of an analysis of the heat- and mass-transfer characteristics of the device are given.

A mini-type hydrogen generator from aluminum for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Wang, Er-Dong; Shi, Peng-Fei; Du, Chun-Yu; Wang, Xiao-Rui

A safe and simple hydrogen generator, which produced hydrogen by chemical reaction of aluminum and sodium hydroxide solution, was proposed for proton exchange membrane fuel cells. The effects of concentration, dropping rate and initial temperature of sodium hydroxide solution on hydrogen generation rate were investigated. The results showed that about 38 ml min -1 of hydrogen generation rate was obtained with 25 wt.% concentration and 0.01 ml s -1 dropping rate of sodium hydroxide solution. The cell fueled by hydrogen from the generator exhibited performance improvement at low current densities, which was mainly due to the humidified hydrogen reduced the protonic resistivity of the proton exchange membrane. The hydrogen generator could stably operate a single cell under 500 mA for nearly 5 h with about 77% hydrogen utilization ratio.

Chitosan/silica coated carbon nanotubes composite proton exchange membranes for fuel cell applications.

PubMed

Liu, Hai; Gong, Chunli; Wang, Jie; Liu, Xiaoyan; Liu, Huanli; Cheng, Fan; Wang, Guangjin; Zheng, Genwen; Qin, Caiqin; Wen, Sheng

2016-01-20

Silica-coated carbon nanotubes (SCNTs), which were obtained by a simple sol-gel method, were utilized in preparation of chitosan/SCNTs (CS/SCNTs) composite membranes. The thermal and oxidative stability, morphology, mechanical properties, water uptake and proton conductivity of CS/SCNTs composite membranes were investigated. The insulated and hydrophilic silica layer coated on CNTs eliminates the risk of electronic short-circuiting and enhances the interaction between SCNTs and chitosan to ensure the homogenous dispersion of SCNTs, although the water uptake of CS/SCNTs membranes is reduced owing to the decrease of the effective number of the amino functional groups of chitosan. The CS/SCNTs composite membranes are superior to the pure CS membrane in thermal and oxidative stability, mechanical properties and proton conductivity. The results of this study suggest that CS/SCNTs composite membranes exhibit promising potential for practical application in proton exchange membranes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis and properties of reprocessable sulfonated polyimides cross-linked via acid stimulation for use as proton exchange membranes

NASA Astrophysics Data System (ADS)

Zhang, Boping; Ni, Jiangpeng; Xiang, Xiongzhi; Wang, Lei; Chen, Yongming

2017-01-01

Cross-linked sulfonated polyimides are one of the most promising materials for proton exchange membrane (PEM) applications. However, these cross-linked membranes are difficult to reprocess because they are insoluble. In this study, a series of cross-linkable sulfonated polyimides with flexible pendant alkyl side chains containing trimethoxysilyl groups is successfully synthesized. The cross-linkable polymers are highly soluble in common solvents and can be used to prepare tough and smooth films. Before the cross-linking reaction is complete, the membranes can be reprocessed, and the recovery rate of the prepared films falls within an acceptable range. The cross-linked membranes are obtained rapidly when the cross-linkable membranes are immersed in an acid solution, yielding a cross-linking density of the gel fraction of greater than 90%. The cross-linked membranes exhibit high proton conductivities and tensile strengths under hydrous conditions. Compared with those of pristine membranes, the oxidative and hydrolytic stabilities of the cross-linked membranes are significantly higher. The CSPI-70 membrane shows considerable power density in a direct methanol fuel cell (DMFC) test. All of these results suggest that the prepared cross-linked membranes have great potential for applications in proton exchange membrane fuel cells.

The transfer behavior of different ions across anion and cation exchange membranes under vanadium flow battery medium

NASA Astrophysics Data System (ADS)

Sun, Jiawei; Li, Xianfeng; Xi, Xiaoli; Lai, Qinzhi; Liu, Tao; Zhang, Huamin

2014-12-01

The transfer behavior of different ions (V2+, V3+, VO2+, VO2+, H+, SO42-) across ion exchange membranes is investigated under vanadium flow battery (VFB) operating condition. VX-20 anion exchange membrane (AEM) and Nafion 115 cation exchange membrane (CEM) are selected to investigate the influence of fixed charged groups on the transfer behavior of different ions. The interaction between different ions and water is discussed in detail aiming to ascertain the variation of different ions in the charge-discharge process. Under the VFB medium, the transfer behavior and function of different ions are very different for the AEM and CEM. V2+ ions at the negative side accumulate when VFB is assembled with Nafion 115, while the VO2+ ions at the positive side accumulate for VX-20. The SO42- ions will transfer across Nafion 115 to balance the charges and the protons can balance the charges of VX-20. Finally the capacity fade mechanism of different membranes is investigated, showing that the capacity decay of VFB assembled with Nafion 115 mainly results from the cross mix of vanadium ions across the membrane, however, for VX-20, the side reactions can be the major reason. This paper provides important information about electrolyte for the application of VFB.

Highly efficient sulfonated polybenzimidazole as a proton exchange membrane for microbial fuel cells

NASA Astrophysics Data System (ADS)

Singha, Shuvra; Jana, Tushar; Modestra, J. Annie; Naresh Kumar, A.; Mohan, S. Venkata

2016-06-01

Although microbial fuel cells (MFCs) represent a promising bio-energy technology with a dual advantage (i.e., electricity production and waste-water treatment), their low power densities and high installation costs are major impediments. To address these bottlenecks and replace highly expensive Nafion, which is a proton exchange membrane (PEM), the current study focuses for the first time on membranes made from an easily synthesizable and more economical oxy-polybenzimidazole (OPBI) and its sulfonated analogue (S-OPBI) as alternate PEMs in single-chambered MFCs. The S-OPBI membrane exhibits better properties, with high water uptake, ion exchange capacity (IEC) and proton conductivity and a comparatively smaller degree of swelling compared to Nafion. The membrane morphology is characterized by atomic force microscopy, and the bright and dark regions of the S-OPBI membrane reveals the formation of ionic domains in the matrix, forming continuous water nanochannels when doped with water. These water-filled nanochannels are responsible for faster proton conduction in S-OPBI than in Nafion; therefore, the power output in the MFC with S-OPBI as the PEM is higher than in other MFCs. The open circuit voltage (460 mV), current generation (2.27 mA) and power density profile (110 mW/m2) as a function of time, as well as the polarization curves, exhibits higher current and power density (87.8 mW/m2) with S-OPBI compared to Nafion as the PEM.

Fluorinated poly(ether sulfone) ionomers with disulfonated naphthyl pendants for proton exchange membrane applications

NASA Astrophysics Data System (ADS)

Hu, Zhaoxia; Lu, Yao; Zhang, Xulve; Yan, Xiaobo; Li, Na; Chen, Shouwen

2018-06-01

Proton exchange membranes based on fluorinated poly(ether sulfone)s with disulfonated naphthyl pendants (sSPFES) have been successfully prepared by post functionalization through polymeric SNAr reaction. Copolymer structure was confirmed by H-nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy, the physico-chemical properties of the sSPFES membranes were evaluated by thermogravimetric analysis, gel permeation chromatography, electro-chemical impedance spectroscopy, atomic force microscopy, Fenton, water-swelling and fuel cell test. The pendant grafting degree was controlled by varying the feeding amount of the disulfonaphthols, resulting in the ion exchange capacity about 1.28-1.73 mmol/g. The obtained sSPFES membranes were thermal stable, mechanical ductile, and exhibited dimensional change less than 17%, water uptake below 70%, and proton conductivity as high as 0.17-0.28 S/cm at 90°C in water. In a single H2/O2 fuel cell test at 80°C, the sSPFES-B-3.2 membrane (1.61 mmol/g) showed the maximum power output of 593-658 mW/cm2 at 60%-80% relative humidity, indicating their rather promising potential for fuel cell applications.

Fluorinated poly(ether sulfone) ionomers with disulfonated naphthyl pendants for proton exchange membrane applications

NASA Astrophysics Data System (ADS)

Hu, Zhaoxia; Lu, Yao; Zhang, Xulve; Yan, Xiaobo; Li, Na; Chen, Shouwen

2018-05-01

Proton exchange membranes based on fluorinated poly(ether sulfone)s with disulfonated naphthyl pendants (sSPFES) have been successfully prepared by post functionalization through polymeric SNAr reaction. Copolymer structure was confirmed by H-nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy, the physico-chemical properties of the sSPFES membranes were evaluated by thermogravimetric analysis, gel permeation chromatography, electro-chemical impedance spectroscopy, atomic force microscopy, Fenton, water-swelling and fuel cell test. The pendant grafting degree was controlled by varying the feeding amount of the disulfonaphthols, resulting in the ion exchange capacity about 1.28-1.73 mmol/g. The obtained sSPFES membranes were thermal stable, mechanical ductile, and exhibited dimensional change less than 17%, water uptake below 70%, and proton conductivity as high as 0.17-0.28 S/cm at 90°C in water. In a single H2/O2 fuel cell test at 80°C, the sSPFES-B-3.2 membrane (1.61 mmol/g) showed the maximum power output of 593-658 mW/cm2 at 60%-80% relative humidity, indicating their rather promising potential for fuel cell applications.

Amphoteric Ion-Exchange Membranes with Significantly Improved Vanadium Barrier Properties for All-Vanadium Redox Flow Batteries.

PubMed

Nibel, Olga; Rojek, Tomasz; Schmidt, Thomas J; Gubler, Lorenz

2017-07-10

All-vanadium redox flow batteries (VRBs) have attracted considerable interest as promising energy-storage devices that can allow the efficient utilization of renewable energy sources. The membrane, which separates the porous electrodes in a redox flow cell, is one of the key components in VRBs. High rates of crossover of vanadium ions and water through the membrane impair the efficiency and capacity of a VRB. Thus, membranes with low permeation rate of vanadium species and water are required, also characterized by low resistance and stability in the VRB environment. Here, we present a new design concept for amphoteric ion-exchange membranes, based on radiation-induced grafting of vinylpyridine into an ethylene tetrafluoroethylene base film and a two-step functionalization to introduce cationic and anionic exchange sites, respectively. During long-term cycling, redox flow cells containing these membranes showed higher efficiency, less pronounced electrolyte imbalance, and significantly reduced capacity decay compared to the cells with the benchmark material Nafion 117. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved Round Trip Efficiency for Regenerative Fuel Cell Systems

DTIC Science & Technology

2012-05-11

advanced components that enable closed-loop, zero emission, low signature energy storage. The system utilizes proton exchange membrane ( PEM ) fuel cell ...regenerative fuel cell (RFC) systems based on proton exchange membrane ( PEM ) technology. An RFC consists of a fuel cell powerplant, an electrolysis...based on an air independent, hydrogen-oxygen, PEM RFC is feasible within the near term if development efforts proceed forward. Fuel Cell

Nanostructure-based proton exchange membrane for fuel cell applications at high temperature.

PubMed

Li, Junsheng; Wang, Zhengbang; Li, Junrui; Pan, Mu; Tang, Haolin

2014-02-01

As a clean and highly efficient energy source, the proton exchange membrane fuel cell (PEMFC) has been considered an ideal alternative to traditional fossil energy sources. Great efforts have been devoted to realizing the commercialization of the PEMFC in the past decade. To eliminate some technical problems that are associated with the low-temperature operation (such as catalyst poisoning and poor water management), PEMFCs are usually operated at elevated temperatures (e.g., > 100 degrees C). However, traditional proton exchange membrane (PEM) shows poor performance at elevated temperature. To achieve a high-performance PEM for high temperature fuel cell applications, novel PEMs, which are based on nanostructures, have been developed recently. In this review, we discuss and summarize the methods for fabricating the nanostructure-based PEMs for PEMFC operated at elevated temperatures and the high temperature performance of these PEMs. We also give an outlook on the rational design and development of the nanostructure-based PEMs.

Infectious polymorphic toxins delivered by outer membrane exchange discriminate kin in myxobacteria.

PubMed

Vassallo, Christopher N; Cao, Pengbo; Conklin, Austin; Finkelstein, Hayley; Hayes, Christopher S; Wall, Daniel

2017-08-18

Myxobacteria are known for complex social behaviors including outer membrane exchange (OME), in which cells exchange large amounts of outer membrane lipids and proteins upon contact. The TraA cell surface receptor selects OME partners based on a variable domain. However, traA polymorphism alone is not sufficient to precisely discriminate kin. Here, we report a novel family of OME-delivered toxins that promote kin discrimination of OME partners. These SitA lipoprotein toxins are polymorphic and widespread in myxobacteria. Each sitA is associated with a cognate sitI immunity gene, and in some cases a sitB accessory gene. Remarkably, we show that SitA is transferred serially between target cells, allowing the toxins to move cell-to-cell like an infectious agent. Consequently, SitA toxins define strong identity barriers between strains and likely contribute to population structure, maintenance of cooperation, and strain diversification. Moreover, these results highlight the diversity of systems evolved to deliver toxins between bacteria.

Haemocompatibility and ion exchange capability of nanocellulose polypyrrole membranes intended for blood purification

PubMed Central

Ferraz, Natalia; Carlsson, Daniel O.; Hong, Jaan; Larsson, Rolf; Fellström, Bengt; Nyholm, Leif; Strømme, Maria; Mihranyan, Albert

2012-01-01

Composites of nanocellulose and the conductive polymer polypyrrole (PPy) are presented as candidates for a new generation of haemodialysis membranes. The composites may combine active ion exchange with passive ultrafiltration, and the large surface area (about 80 m2 g−1) could potentially provide compact dialysers. Herein, the haemocompatibility of the novel membranes and the feasibility of effectively removing small uraemic toxins by potential-controlled ion exchange were studied. The thrombogenic properties of the composites were improved by applying a stable heparin coating. In terms of platelet adhesion and thrombin generation, the composites were comparable with haemocompatible polymer polysulphone, and regarding complement activation, the composites were more biocompatible than commercially available membranes. It was possible to extract phosphate and oxalate ions from solutions with physiological pH and the same tonicity as that of the blood. The exchange capacity of the materials was found to be 600 ± 26 and 706 ± 31 μmol g−1 in a 0.1 M solution (pH 7.4) and in an isotonic solution of phosphate, respectively. The corresponding values with oxalate were 523 ± 5 in a 0.1 M solution (pH 7.4) and 610 ± 1 μmol g−1 in an isotonic solution. The heparinized PPy–cellulose composite is consequently a promising haemodialysis material, with respect to both potential-controlled extraction of small uraemic toxins and haemocompatibility. PMID:22298813

Solid oxide membrane (SOM) process for ytterbium and silicon production from their oxides

NASA Astrophysics Data System (ADS)

Jiang, Yihong

The Solid oxide membrane (SOM) electrolysis is an innovative green technology that produces technologically important metals directly from their respective oxides. A yttria-stabilized zirconia (YSZ) tube, closed at one end is employed to separate the molten salt containing dissolved metal oxides from the anode inside the YSZ tube. When the applied electric potential between the cathode in the molten salt and the anode exceeds the dissociation potential of the desired metal oxides, oxygen ions in the molten salt migrate through the YSZ membrane and are oxidized at the anode while the dissolved metal cations in the flux are reduced to the desired metal at the cathode. Compared with existing metal production processes, the SOM process has many advantages such as one unit operation, less energy consumption, lower capital costs and zero carbon emission. Successful implementation of the SOM electrolysis process would provide a way to mitigate the negative environmental impact of the metal industry. Successful demonstration of producing ytterbium (Yb) and silicon (Si) directly from their respective oxides utilizing the SOM electrolysis process is presented in this dissertation. During the SOM electrolysis process, Yb2O3 was reduced to Yb metal on an inert cathode. The melting point of the supporting electrolyte (LiF-YbF3-Yb2O3) was determined by differential thermal analysis (DTA). Static stability testing confirmed that the YSZ tube was stable with the flux at operating temperature. Yb metal deposit on the cathode was confirmed by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). During the SOM electrolysis process for silicon production, a fluoride based flux based on BaF2, MgF2, and YF3 was engineered to serve as the liquid electrolyte for dissolving silicon dioxide. YSZ tube was used to separate the molten salt from an anode current collector in the liquid silver. Liquid tin was chosen as cathode to dissolve the reduced silicon during

Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms

PubMed Central

Widdows, Kate L.; Panitchob, Nuttanont; Crocker, Ian P.; Please, Colin P.; Hanson, Mark A.; Sibley, Colin P.; Johnstone, Edward D.; Sengers, Bram G.; Lewis, Rohan M.; Glazier, Jocelyn D.

2015-01-01

Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L amino acid exchange transporters are not fully obligatory and/or that amino acids are initially present inside the vesicles. To address this, we combined computational modeling with vesicle transport assays and transporter localization studies to investigate the mechanisms mediating [14C]l-serine (a system L substrate) transport into human placental microvillous plasma membrane (MVM) vesicles. The carrier model provided a quantitative framework to test the 2 hypotheses that l-serine transport occurs by either obligate exchange or nonobligate exchange coupled with facilitated transport (mixed transport model). The computational model could only account for experimental [14C]l-serine uptake data when the transporter was not exclusively in exchange mode, best described by the mixed transport model. MVM vesicle isolates contained endogenous amino acids allowing for potential contribution to zero-trans uptake. Both L-type amino acid transporter (LAT)1 and LAT2 subtypes of system L were distributed to MVM, with l-serine transport attributed to LAT2. These findings suggest that exchange transporters do not function exclusively as obligate exchangers.—Widdows, K. L., Panitchob, N., Crocker, I. P., Please, C. P., Hanson, M. A., Sibley, C. P., Johnstone, E. D., Sengers, B. G., Lewis, R. M., Glazier, J. D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms. PMID:25761365

Chemicals and energy co-generation from direct hydrocarbons/oxygen proton exchange membrane fuel cell

NASA Astrophysics Data System (ADS)

Li, W. S.; Lu, D. S.; Luo, J. L.; Chuang, K. T.

A proton exchange membrane fuel cell for chemicals and energy co-generation was set up with hydrocarbons ethane, propane and butane as fuels, and the electrochemical performance of the cell was studied by using linear potential sweep, alternating current impedance and gas chromatography. The cell performance can be improved to a great extent by increasing the platinum load in the catalyst, by treating the membrane with phosphoric acid and by elevating temperature. The improvement of cell performance by the increase of platinum load is ascribed to the increase of reaction sites for hydrocarbon oxidation, that by phosphoric acid treatment to the increase of proton conductivity in Nafion membrane, and that by elevating temperature to the improvement in thermodynamic as well as kinetic aspects. Only a small fraction of the hydrocarbon is converted to carbon dioxide in this cell during its power generation. The current efficiency is 5% for the conversion of ethane to carbon dioxide in the ethane/oxygen fuel cell with 20% carbon-supported platinum as catalyst and phosphoric acid-treated membrane as proton exchange membrane at 0.2 V, 80 °C and ambient pressure. The reaction activity of hydrocarbons at the anode is in the order of propane, butane and ethane. The possible chemicals produced from the cell were hydrocarbons with more than six carbons, which are inactive at the anode under cell conditions.

Study and development of sulfated zirconia based proton exchange fuel cell membranes

NASA Astrophysics Data System (ADS)

Kemp, Brittany Wilson

With the increasing consumption of energy, fuel cells are among the most promising alternatives to fossil fuels, provided some technical challenges are overcome. Proton exchange membrane fuel cells (PEMFCs) have been investigated and improvements have been made, but the problem with NafionRTM, the main membrane for PEMFCs, has not been solved. NafionRTM restricts the membranes from operating at higher temperatures, thus preventing them from working in small electronics. The problem is to develop a novel fuel cell membrane that performs comparably to NafionRTM in PEMFCs. The membranes were fabricated by applying sulfated zirconia, via template wetting, to porous alumina membranes. The fabricated membranes showed a proton conductivity of 0.016 S/cm in comparison to the proton conductivity of Nafion RTM (0.05 S/cm). Both formic acid and methanol had a lower crossover flux through the sulfated zirconia membranes (formic acid- 2.89x10 -7 mols/cm2s and methanol-1.78x10-9 mols/cm2s) than through NafionRTM (formic acid-2.03x10 -8 mols/cm2s methanol-2.42x10-6 mols/cm 2s), indicating that a sulfated zirconia PEMFC may serve as a replacement for NafionRTM.

Removal of Congo Red from Aqueous Solution by Anion Exchange Membrane (EBTAC): Adsorption Kinetics and Themodynamics.

PubMed

Khan, Muhammad Imran; Akhtar, Shahbaz; Zafar, Shagufta; Shaheen, Aqeela; Khan, Muhammad Ali; Luque, Rafael; Rehman, Aziz Ur

2015-07-08

The adsorption behavior of anionic dye congo red (CR) from aqueous solutions using an anion exchange membrane (EBTAC) has been investigated at room temperature. The effect of several factors including contact time, membrane dosage, ionic strength and temperature were studied. Kinetic models, namely pseudo-first-order and pseudo-second-order, liquid film diffusion and Elovich models as well as Bangham and modified freundlich Equations, were employed to evaluate the experimental results. Parameters such as adsorption capacities, rate constant and related correlation coefficients for every model were calculated and discussed. The adsorption of CR on anion exchange membranes followed pseudo-second-order Kinetics. Thermodynamic parameters, namely changes in Gibbs free energy ( ∆G° ), enthalpy ( ∆H° ) and entropy ( ∆S° ) were calculated for the adsorption of congo red, indicating an exothermic process.

Removal of Congo Red from Aqueous Solution by Anion Exchange Membrane (EBTAC): Adsorption Kinetics and Themodynamics

PubMed Central

Khan, Muhammad Imran; Akhtar, Shahbaz; Zafar, Shagufta; Shaheen, Aqeela; Khan, Muhammad Ali; Luque, Rafael; ur Rehman, Aziz

2015-01-01

The adsorption behavior of anionic dye congo red (CR) from aqueous solutions using an anion exchange membrane (EBTAC) has been investigated at room temperature. The effect of several factors including contact time, membrane dosage, ionic strength and temperature were studied. Kinetic models, namely pseudo-first-order and pseudo-second-order, liquid film diffusion and Elovich models as well as Bangham and modified freundlich Equations, were employed to evaluate the experimental results. Parameters such as adsorption capacities, rate constant and related correlation coefficients for every model were calculated and discussed. The adsorption of CR on anion exchange membranes followed pseudo-second-order Kinetics. Thermodynamic parameters, namely changes in Gibbs free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) were calculated for the adsorption of congo red, indicating an exothermic process. PMID:28793430

Preparations of an inorganic-framework proton exchange nanochannel membrane

NASA Astrophysics Data System (ADS)

Yan, X. H.; Jiang, H. R.; Zhao, G.; Zeng, L.; Zhao, T. S.

2016-09-01

In this work, a proton exchange membrane composed of straight and aligned proton conducting nanochannels is developed. Preparation of the membrane involves the surface sol-gel method assisted with a through-hole anodic aluminum oxide (AAO) template to form the framework of the PEM nanochannels. A monomolecular layer (SO3Hsbnd (CH2)3sbnd Sisbnd (OCH3)3) is subsequently added onto the inner surfaces of the nanochannels to shape a proton-conducting pathway. Straight nanochannels exhibit long range order morphology, contributing to a substantial improvement in the proton mobility and subsequently proton conductivity. In addition, the nanochannel size can be altered by changing the surface sol-gel condition, allowing control of the active species/charge carrier selectivity via pore size exclusion. The proton conductivity of the nanochannel membrane is reported as high as 11.3 mS cm-1 at 70 °C with a low activation energy of 0.21 eV (20.4 kJ mol-1). First-principle calculations reveal that the activation energy for proton transfer is impressively low (0.06 eV and 0.07 eV) with the assistance of water molecules.

Gold Nanoparticles-Enhanced Proton Exchange Membrane (PEM) Fuel Cell

NASA Astrophysics Data System (ADS)

Li, Hongfei; Pan, Cheng; Liu, Ping; Zhu, Yimei; Adzic, Radoslav; Rafailovich, Miriam

Proton exchange membrane fuel cells have drawn great attention and been taken as a promising alternated energy source. One of the reasons hamper the wider application of PEM fuel cell is the catalytic poison effect from the impurity of the gas flow. Haruta has predicted that gold nanoparticles that are platelet shaped and have direct contact with the metal oxide substrate to be the perfect catalysts of the CO oxidization, yet the synthesis method is difficult to apply in the Fuel Cell. In our approach, thiol-functionalized gold nanoparticles were synthesized through two-phase method developed by Brust et al. We deposit these Au particles with stepped surface directly onto the Nafion membrane in the PEM fuel cell by Langmuir-Blodgett method, resulting in over 50% enhancement of the efficiency of the fuel cell. DFT calculations were conducted to understand the theory of this kind of enhancement. The results indicated that only when the particles were in direct surface contact with the membrane, where AuNPs attached at the end of the Nafion side chains, it could reduce the energy barrier for the CO oxidation that could happen at T<300K.

Semi-interpenetrating polymer network proton exchange membranes with narrow and well-connected hydrophilic channels

NASA Astrophysics Data System (ADS)

Fang, Chunliu; Toh, Xin Ni; Yao, Qiaofeng; Julius, David; Hong, Liang; Lee, Jim Yang

2013-03-01

Four series of semi-interpenetrating polymer network (SIPN) membranes are fabricated by thermally cross-linking aminated BPPO (brominated poly(2,6-dimethyl-1,4-phenylene oxide)) with different epoxide cross-linkers in the presence of sulfonated PPO (SPPO). The cross-link structure and hydrophobicity are found to impact the membrane morphology strongly - smaller and more hydrophobic cross-links form narrow and well-connected hydrophilic channels whereas bulky and less hydrophobic cross-links form wide but less-connected hydrophilic channels. The membranes of the former can support facile proton transport and suppress methanol crossover to result in higher proton conductivity and lower methanol permeability than the membranes of the latter. The membranes are also fabricated into membrane electrode assemblies (MEAs) and tested in single-stack direct methanol fuel cells (DMFCs). It is found that some of these SIPN membranes can surpass Nafion® 117 in maximum power density, demonstrating their potential as a proton exchange membrane (PEM) for the DMFCs.

Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane

PubMed Central

Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

2016-01-01

A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl−/SO42− separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl−/SO42− permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later. PMID:27853255

Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane.

PubMed

Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

2016-11-17

A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl - /SO 4 2- separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl - /SO 4 2- permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm 2 30 minutes later.

Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane

NASA Astrophysics Data System (ADS)

Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

2016-11-01

A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl-/SO42- separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl-/SO42- permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later.

High Temperature Electrolysis using Electrode-Supported Cells

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

J. E. O'Brien; C. M. Stoots

2010-07-01

An experimental study is under way to assess the performance of electrode-supported solid-oxide cells operating in the steam electrolysis mode for hydrogen production. The cells currently under study were developed primarily for the fuel cell mode of operation. Results presented in this paper were obtained from single cells, with an active area of 16 cm2 per cell. The electrolysis cells are electrode-supported, with yttria-stabilized zirconia (YSZ) electrolytes (~10 µm thick), nickel-YSZ steam/hydrogen electrodes (~1400 µm thick), and manganite (LSM) air-side electrodes (~90 µm thick). The purpose of the present study was to document and compare the performance and degradation ratesmore » of these cells in the fuel cell mode and in the electrolysis mode under various operating conditions. Initial performance was documented through a series of DC potential sweeps and AC impedance spectroscopy measurements. Degradation was determined through long-duration testing, first in the fuel cell mode, then in the electrolysis mode over more than 500 hours of operation. Results indicate accelerated degradation rates in the electrolysis mode compared to the fuel cell mode, possibly due to electrode delamination. The paper also includes details of the single-cell test apparatus developed specifically for these experiments.« less

Space Station propulsion electrolysis system - 'A technology challenge'

NASA Technical Reports Server (NTRS)

Le, Michael

1989-01-01

The Space Station propulsion system will utilize a water electrolysis system to produce the required eight-to-one ratio of gaseous hydrogen and oxygen propellants. This paper summarizes the state of the art in water electrolysis technologies and the supporting development programs at the NASA Lyndon B. Johnson Space Center. Preliminary proof of concept test data from a fully integrated propulsion testbed are discussed. The technical challenges facing the development of the high-pressure water electrolysis system are discussed.

Solar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30%

PubMed Central

Jia, Jieyang; Seitz, Linsey C.; Benck, Jesse D.; Huo, Yijie; Chen, Yusi; Ng, Jia Wei Desmond; Bilir, Taner; Harris, James S.; Jaramillo, Thomas F.

2016-01-01

Hydrogen production via electrochemical water splitting is a promising approach for storing solar energy. For this technology to be economically competitive, it is critical to develop water splitting systems with high solar-to-hydrogen (STH) efficiencies. Here we report a photovoltaic-electrolysis system with the highest STH efficiency for any water splitting technology to date, to the best of our knowledge. Our system consists of two polymer electrolyte membrane electrolysers in series with one InGaP/GaAs/GaInNAsSb triple-junction solar cell, which produces a large-enough voltage to drive both electrolysers with no additional energy input. The solar concentration is adjusted such that the maximum power point of the photovoltaic is well matched to the operating capacity of the electrolysers to optimize the system efficiency. The system achieves a 48-h average STH efficiency of 30%. These results demonstrate the potential of photovoltaic-electrolysis systems for cost-effective solar energy storage. PMID:27796309

Solar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30.

PubMed

Jia, Jieyang; Seitz, Linsey C; Benck, Jesse D; Huo, Yijie; Chen, Yusi; Ng, Jia Wei Desmond; Bilir, Taner; Harris, James S; Jaramillo, Thomas F

2016-10-31

Hydrogen production via electrochemical water splitting is a promising approach for storing solar energy. For this technology to be economically competitive, it is critical to develop water splitting systems with high solar-to-hydrogen (STH) efficiencies. Here we report a photovoltaic-electrolysis system with the highest STH efficiency for any water splitting technology to date, to the best of our knowledge. Our system consists of two polymer electrolyte membrane electrolysers in series with one InGaP/GaAs/GaInNAsSb triple-junction solar cell, which produces a large-enough voltage to drive both electrolysers with no additional energy input. The solar concentration is adjusted such that the maximum power point of the photovoltaic is well matched to the operating capacity of the electrolysers to optimize the system efficiency. The system achieves a 48-h average STH efficiency of 30%. These results demonstrate the potential of photovoltaic-electrolysis systems for cost-effective solar energy storage.

Photoinitiated Bottom-Up Click Synthesis of Ion-Containing Networks as Hydroxide Exchange Membranes

NASA Astrophysics Data System (ADS)

Tibbits, Andrew Charles

Fuel cells are energy conversion devices which directly convert chemical energy into electrical energy and environmentally friendly byproducts (i.e., water) with potential versatility for transportation and portable applications. Hydroxide exchange membrane fuel cells (HEMFCs) have the potential to decrease the overall fuel cell cost through the utilization of non-precious metal catalysts such as nickel and silver as opposed to platinum which is used by the current standard technology, proton exchange membrane fuel cells (PEMFCs). However, substantial improvements in thermal and alkaline stability, hydroxide conductivity, mechanical flexibility, and processing are needed to create a competitive membrane for HEMFC applications. Regardless of the type of membrane, the high water uptake that is typically associated with increased ionic conductivity is problematic and can result in the dissolution of the membrane during fuel cell operation. Covalent crosslinking of the membrane is an approach which has been effectively applied to reduce water uptake without a significant compromise of the hydroxide conductivity. The synthesis and processing of membrane materials is vastly simplified by using click polymerization schemes. Click chemistry is a collection of organic chemical reactions that are rapid, selective, and high yielding. One of the most versatile and facile click reactions is the thiol-ene reaction, which is the radical-mediated addition reaction between a thiol (an -SH group) and an 'ene' (an electron rich vinyl group, C=C) in the presence of a photoinitiator and light. The click attributes of the thiol-ene reaction enables potential of "bottom-up" design of ion-containing polymers via a single step photoinitiated crosslinking reaction with precise control over structure and physicochemical properties not only for fuel cell membranes but also for a range of other applications including separations, sensors, flexible electronics, and coatings. However, a

Anion exchange membrane fuel cell modelling

NASA Astrophysics Data System (ADS)

Fragiacomo, P.; Astorino, E.; Chippari, G.; De Lorenzo, G.; Czarnetzki, W. T.; Schneider, W.

2018-04-01

A parametric model predicting the performance of a solid polymer electrolyte, anion exchange membrane fuel cell (AEMFC), has been developed, in Matlab environment, based on interrelated electrical and thermal models. The electrical model proposed is developed by modelling an AEMFC open-circuit output voltage, irreversible voltage losses along with a mass balance, while the thermal model is based on the energy balance. The proposed model of the AEMFC stack estimates its dynamic behaviour, in particular the operating temperature variation for different discharge current values. The results of the theoretical fuel cell (FC) stack are reported and analysed in order to highlight the FC performance and how it varies by changing the values of some parameters such as temperature and pressure. Both the electrical and thermal FC models were validated by comparing the model results with experimental data and the results of other models found in the literature.

Towards neat methanol operation of direct methanol fuel cells: a novel self-assembled proton exchange membrane.

PubMed

Li, Jing; Cai, Weiwei; Ma, Liying; Zhang, Yunfeng; Chen, Zhangxian; Cheng, Hansong

2015-04-18

We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol.

Advances in proton-exchange membranes for fuel cells: an overview on proton conductive channels (PCCs).

PubMed

Wu, Liang; Zhang, Zhenghui; Ran, Jin; Zhou, Dan; Li, Chuanrun; Xu, Tongwen

2013-04-14

Proton-exchange membranes (PEM) display unique ion-selective transport that has enabled a breakthrough in high-performance proton-exchange membrane fuel cells (PEMFCs). Elemental understanding of the morphology and proton transport mechanisms of the commercially available Nafion® has promoted a majority of researchers to tune proton conductive channels (PCCs). Specifically, knowledge of the morphology-property relationship gained from statistical and segmented copolymer PEMs has highlighted the importance of the alignment of PCCs. Furthermore, increasing efforts in fabricating and aligning artificial PCCs in field-aligned copolymer PEMs, nanofiber composite PEMs and mesoporous PEMs have set new paradigms for improvement of membrane performances. This perspective profiles the recent development of the channels, from the self-assembled to the artificial, with a particular emphasis on their formation and alignment. It concludes with an outlook on benefits of highly aligned PCCs for fuel cell operation, and gives further direction to develop new PEMs from a practical point of view.

Towards high conductivity in anion-exchange membranes for alkaline fuel cells.

PubMed

Li, Nanwen; Guiver, Michael D; Binder, Wolfgang H

2013-08-01

Quaternized poly(2,6-dimethylphenylene oxide) materials (PPOs) containing clicked 1,2,3-triazoles were first prepared through Cu(I) -catalyzed "click chemistry" to improve the anion transport in anion-exchange membranes (AEMs). Clicked 1,2,3-triazoles incorporated into AEMs provided more sites to form efficient and continuous hydrogen-bond networks between the water/hydroxide and the triazole for anion transport. Higher water uptake was observed for these triazole membranes. Thus, the membranes showed an impressive enhancement of the hydroxide diffusion coefficient and, therefore, the anion conductivities. The recorded hydroxide conductivity was 27.8-62 mS cm(-1) at 20 °C in water, which was several times higher than that of a typical PPO-based AEM (TMA-20) derived from trimethylamine (5 mS cm(-1) ). Even at reduced relative humidity, the clicked membrane showed superior conductivity to a trimethylamine-based membrane. Moreover, similar alkaline stabilities at 80 °C in 1 M NaOH were observed for the clicked and non-clicked membranes. The performance of a H2 /O2 single cell assembled with a clicked AEM was much improved compared to that of a non-clicked TMA-20 membrane. The peak power density achieved for an alkaline fuel cell with the synthesized membrane 1a(20) was 188.7 mW cm(-2) at 50 °C. These results indicated that clicked AEM could be a viable strategy for improving the performance of alkaline fuel cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simple Electrolyzer Model Development for High-Temperature Electrolysis System Analysis Using Solid Oxide Electrolysis Cell

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

JaeHwa Koh; DuckJoo Yoon; Chang H. Oh

2010-07-01

An electrolyzer model for the analysis of a hydrogen-production system using a solid oxide electrolysis cell (SOEC) has been developed, and the effects for principal parameters have been estimated by sensitivity studies based on the developed model. The main parameters considered are current density, area specific resistance, temperature, pressure, and molar fraction and flow rates in the inlet and outlet. Finally, a simple model for a high-temperature hydrogen-production system using the solid oxide electrolysis cell integrated with very high temperature reactors is estimated.

Water electrolysis system refurbishment and testing

NASA Technical Reports Server (NTRS)

Greenough, B. M.

1972-01-01

The electrolytic oxygen generator for the back-up water electrolysis system in a 90-day manned test was refurbished, improved and subjected to a 182-day bench test. The performance of the system during the test demonstrated the soundness of the basic electrolysis concept, the high development status of the automatic controls which allowed completely hands-off operation, and the capability for orbital operation. Some design improvements are indicated.

Recyclable cross-linked anion exchange membrane for alkaline fuel cell application

NASA Astrophysics Data System (ADS)

Hou, Jianqiu; Liu, Yazhi; Ge, Qianqian; Yang, Zhengjin; Wu, Liang; Xu, Tongwen

2018-01-01

Cross-linking can effectively solve the conductivity-swelling dilemma in anion exchange membranes (AEMs) but will generate solid wastes. To address this, we developed an AEM cross-linked via disulfide bonds, bearing quaternary ammonium groups, which can be easily recycled. The membrane (RC-QPPO) with IEC of 1.78 mmol g-1, when cross-linked, showed enhanced mechanical properties and good hydroxide conductivity (24.6 mS cm-1 at 30 °C). Even at higher IEC value (2.13 mmol g-1), it still has low water uptake, low swelling ratio and delivers a peak power density of 150 mW cm-2 at 65 °C. Exploiting the formation of disulfide bonds from -SH groups, the membrane can be readily cross-linked in alkaline condition and recycled by reversibly breaking disulfide bonds with dithiothreitol (DTT). The recycled membrane solution can be directly utilized to cast a brand-new AEM. By washing away the residual DTT with water and exposure to air, it can be cross-linked again and this process is repeatable. During the recycling and cross-linking processes, the membrane showed a slight IEC decrease of 5% due to functional group degradation. The strategy presented here is promising in enhancing AEM properties and reducing the impact of artificial polymers on the environment.

Plasma graft-polymerization for synthesis of highly stable hydroxide exchange membrane

NASA Astrophysics Data System (ADS)

Hu, Jue; Zhang, Chengxu; Jiang, Lin; Fang, Shidong; Zhang, Xiaodong; Wang, Xiangke; Meng, Yuedong

2014-02-01

A novel plasma graft-polymerization approach is adopted to prepare hydroxide exchange membranes (HEMs) using cardo polyetherketone powders (PEK-C) and vinylbenzyl chloride. The benzylic chloromethyl groups can be successfully introduced into the PEK-C polymer matrix via plasma graft-polymerization. This approach enables a well preservation in the structure of functional groups and formation of a highly cross-linked structure in the membrane, leading to an improvement on the stability and performance of HEMs. The chemical stabilities, including alkaline and oxidative stability, are evaluated under severe conditions by measuring hydroxide conductivity and weight changes during aging. The obtained PGP-NOH membrane retains 86% of the initial hydroxide conductivity in 6 mol L-1 KOH solution at 60 °C for 120 h, and 94% of the initial weight in 3 wt% H2O2 solution at 60 °C for 262 h. The PGP-NOH membrane also possesses excellent thermal stability (safely used below 120 °C), alcohol resistance (ethanol permeability of 6.6 × 10-11 m2 s-1 and diffusion coefficient of 3.7 × 10-13 m2 s-1), and an acceptable hydroxide conductivity (8.3 mS cm-1 at 20 °C in deionized water), suggesting a good candidate of PGP-NOH membrane for HEMFC applications.

Formation of hazardous inorganic by-products during electrolysis of seawater as a disinfection process for desalination.

PubMed

Oh, Byung Soo; Oh, Sang Guen; Hwang, Youn Young; Yu, Hye-Weon; Kang, Joon-Wun; Kim, In S

2010-11-01

From our previous study, an electrochemical process was determined to be a promising tool for disinfection in a seawater desalination system, but an investigation on the production of several hazardous by-products is still required. In this study, a more intensive exploration of the formation patterns of perchlorate and bromate during the electrolysis of seawater was conducted. In addition, the rejection efficiencies of the targeted by-products by membrane processes (microfiltration and seawater reverse osmosis) were investigated to uncover the concentrations remaining in the final product from a membrane-based seawater desalination system for the production of drinking water. On the electrolysis of seawater, perchlorate did not provoke any problem due to the low concentrations formed, but bromate was produced at a much higher level, resulting in critical limitation in the application of the electrochemical process to the desalination of seawater. Even though the formed bromate was rejected via microfiltration and reverse osmosis during the 1st and 2nd passes, the residual concentration was a few orders of magnitude higher than the USEPA regulation. Consequently, it was concluded that the application of the electrochemical process to seawater desalination cannot be recommended without the control of bromate. Copyright © 2010 Elsevier B.V. All rights reserved.

Tin recovery from tin slag using electrolysis method

NASA Astrophysics Data System (ADS)

Jumari, Arif; Purwanto, Agus; Nur, Adrian; Budiman, Annata Wahyu; Lerian, Metty; Paramita, Fransisca A.

2018-02-01

The process in industry, including in mining industry, would surely give negative effect such as waste polluting to the environment. Some of waste could be potentially reutilized to be a commodity with the higher economic value. Tin slag is one of them. The aim of this research was to recover the tin contained in tin slag. Before coming to the electrolysis, tin slag must be treated by dissolution. The grinded tin slag was dissolved into HCl solution to form a slurry. During dissolution, the slurry was agitated and heated, and finally filtered. The filtrate obtained was then electrolyzed. During the process of electrolysis, solid material precipitated on the used cathode. The precipitated solid was then separated and dried. The solid was then analyzed using XRD, XRF and SEM. The XRD analysis showed that the longest time of dissolution and electrolysis the highest the purity obtained in the product. The SEM analysis showed that the longest time of electrolysis the smallest tin particle obtained. Optimum time achieved in this research was 2 hours for the recovering time and 3 hours for the electrolysis time, with 9% tin recovered.

The Cdc42 guanine nucleotide exchange factor FGD6 coordinates cell polarity and endosomal membrane recycling in osteoclasts.

PubMed

Steenblock, Charlotte; Heckel, Tobias; Czupalla, Cornelia; Espírito Santo, Ana Isabel; Niehage, Christian; Sztacho, Martin; Hoflack, Bernard

2014-06-27

The initial step of bone digestion is the adhesion of osteoclasts onto bone surfaces and the assembly of podosomal belts that segregate the bone-facing ruffled membrane from other membrane domains. During bone digestion, membrane components of the ruffled border also need to be recycled after macropinocytosis of digested bone materials. How osteoclast polarity and membrane recycling are coordinated remains unknown. Here, we show that the Cdc42-guanine nucleotide exchange factor FGD6 coordinates these events through its Src-dependent interaction with different actin-based protein networks. At the plasma membrane, FGD6 couples cell adhesion and actin dynamics by regulating podosome formation through the assembly of complexes comprising the Cdc42-interactor IQGAP1, the Rho GTPase-activating protein ARHGAP10, and the integrin interactors Talin-1/2 or Filamin A. On endosomes and transcytotic vesicles, FGD6 regulates retromer-dependent membrane recycling through its interaction with the actin nucleation-promoting factor WASH. These results provide a mechanism by which a single Cdc42-exchange factor controlling different actin-based processes coordinates cell adhesion, cell polarity, and membrane recycling during bone degradation. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Phosphorus-doped glass proton exchange membranes for low temperature direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Prakash, Shruti; Mustain, William E.; Park, SeongHo; Kohl, Paul A.

Phosphorus-doped silicon dioxide thin films were used as ion exchange membranes in low temperature proton exchange membrane fuel cells. Phosphorus-doped silicon dioxide glass (PSG) was deposited via plasma-enhanced chemical vapor deposition (PECVD). The plasma deposition of PSG films allows for low temperature fabrication that is compatible with current microelectronic industrial processing. SiH 4, PH 3 and N 2O were used as the reactant gases. The effect of plasma deposition parameters, substrate temperature, RF power, and chamber pressure, on the ionic conductivity of the PSG films is elucidated. PSG conductivities as high as 2.54 × 10 -4 S cm -1 were realized, which is 250 times higher than the conductivity of pure SiO 2 films (1 × 10 -6 S cm -1) under identical deposition conditions. The higher conductivity films were deposited at low temperature, moderate pressure, limited reactant gas flow rate, and high RF power.

Poly(vinylbenzylchloride) Based Anion-Exchange Blend Membranes (AEBMs): Influence of PEG Additive on Conductivity and Stability

PubMed Central

Kerres, Jochen A.; Krieg, Henning M.

2017-01-01

In view of the many possible applications such as fuel cells and electrolysers, recent interest in novel anion exchange membranes (AEMs) has increased significantly. However, their low conductivity and chemical stability limits their current suitability. In this study, the synthesis and characterization of several three- and four-component anion exchange blend membranes (AEBMs) is described, where the compositions have been systematically varied to study the influence of the AEBM’s composition on the anion conductivities as well as chemical and thermal stabilities under strongly alkaline conditions. It was shown that the epoxide-functionalized poly(ethylene glycol)s that were introduced into the four-component AEBMs resulted in increased conductivity as well as a marked improvement in the stability of the AEBMs in an alkaline environment. In addition, the thermal stability of the novel AEBMs was excellent showing the suitability of these membranes for several electrochemical applications. PMID:28621717

Thermodynamics and Transport Phenomena in High Temperature Steam Electrolysis Cells

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

James E. O'Brien

2012-03-01

Hydrogen can be produced from water splitting with relatively high efficiency using high temperature electrolysis. This technology makes use of solid-oxide cells, running in the electrolysis mode to produce hydrogen from steam, while consuming electricity and high temperature process heat. The overall thermal-to-hydrogen efficiency for high temperature electrolysis can be as high as 50%, which is about double the overall efficiency of conventional low-temperature electrolysis. Current large-scale hydrogen production is based almost exclusively on steam reforming of methane, a method that consumes a precious fossil fuel while emitting carbon dioxide to the atmosphere. An overview of high temperature electrolysis technologymore » will be presented, including basic thermodynamics, experimental methods, heat and mass transfer phenomena, and computational fluid dynamics modeling.« less

Decoupling Hydrogen and Oxygen Production in Acidic Water Electrolysis Using a Polytriphenylamine-Based Battery Electrode.

PubMed

Ma, Yuanyuan; Dong, Xiaoli; Wang, Yonggang; Xia, Yongyao

2018-03-05

Hydrogen production through water splitting is considered a promising approach for solar energy harvesting. However, the variable and intermittent nature of solar energy and the co-production of H 2 and O 2 significantly reduce the flexibility of this approach, increasing the costs of its use in practical applications. Herein, using the reversible n-type doping/de-doping reaction of the solid-state polytriphenylamine-based battery electrode, we decouple the H 2 and O 2 production in acid water electrolysis. In this architecture, the H 2 and O 2 production occur at different times, which eliminates the issue of gas mixing and adapts to the variable and intermittent nature of solar energy, facilitating the conversion of solar energy to hydrogen (STH). Furthermore, for the first time, we demonstrate a membrane-free solar water splitting through commercial photovoltaics and the decoupled acid water electrolysis, which potentially paves the way for a new approach for solar water splitting. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrolysis Performance Improvement Concept Study (EPICS) flight experiment phase C/D

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Lee, M. G.

1995-01-01

The overall purpose of the Electrolysis Performance Improvement Concept Study flight experiment is to demonstrate and validate in a microgravity environment the Static Feed Electrolyzer concept as well as investigate the effect of microgravity on water electrolysis performance. The scope of the experiment includes variations in microstructural characteristics of electrodes and current densities in a static feed electrolysis cell configuration. The results of the flight experiment will be used to improve efficiency of the static feed electrolysis process and other electrochemical regenerative life support processes by reducing power and expanding the operational range. Specific technologies that will benefit include water electrolysis for propulsion, energy storage, life support, extravehicular activity, in-space manufacturing and in-space science in addition to other electrochemical regenerative life support technologies such as electrochemical carbon dioxide and oxygen separation, electrochemical oxygen compression and water vapor electrolysis. The Electrolysis Performance Improvement Concept Study flight experiment design incorporates two primary hardware assemblies: the Mechanical/Electrochemical Assembly and the Control/Monitor Instrumentation. The Mechanical/Electrochemical Assembly contains three separate integrated electrolysis cells along with supporting pressure and temperature control components. The Control/Monitor Instrumentation controls the operation of the experiment via the Mechanical/Electrochemical Assembly components and provides for monitoring and control of critical parameters and storage of experimental data.

Membrane oxygenator heat exchanger failure detected by unique blood gas findings.

PubMed

Hawkins, Justin L

2014-03-01

Failure of components integrated into the cardiopulmonary bypass circuit, although rare, can bring about catastrophic results. One of these components is the heat exchanger of the membrane oxygenator. In this compartment, unsterile water from the heater cooler device is separated from the sterile blood by stainless steel, aluminum, or by polyurethane. These areas are glued or welded to keep the two compartments separate, maintaining sterility of the blood. Although quality control testing is performed by the manufacturer at the factory level, transport presents the real possibility for damage. Because of this, each manufacturer has included in the instructions for use a testing procedure for testing the integrity of the heat exchanger component. Water is circulated through the heat exchanger before priming and a visible check is made of the oxygenator bundle to check for leaks. If none are apparent, then priming of the oxygenator is performed. In this particular case, this procedure was not useful in detecting communication between the water and blood chambers of the oxygenator.

TiO2/bi A-SPAES(Ds 1.0) composite membranes for proton exchange membrane in direct methanol fuel cell (DMFC).

PubMed

Zhang, Ni; Zhong, Chuanqing; Xie, Bing; Liu, Huiling; Wang, Xingzu

2014-09-01

A series of TiO2/bi A-SPAES(Ds 1.0) composite membranes with various contents of nano-sized TiO2 particles were prepared through sol-gel method. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These membranes were used for proton exchange membrane (PEM) for performance evaluation in direct methanol fuel cell (DMFC). These composite membranes showed good thermal stability and mechanical strength. It was found that the water uptake of these membranes enhanced with the TiO2 amount increasing in these composite membranes. Meanwhile, the introduction of TiO2 particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities of these composite membranes with 8% TiO2 particles (0.120 S/cm and 0.128 S/cm) were higher than those of Nafion 117 membrane (0.114 S/cm and 0.117 S/cm) at 80 degrees C and 100 degrees C. Specially, the methanol diffusion coefficient (1.2 x 10(-7) cm2/s) of the composite membrane with 8% TiO2 content was much lower than that of Nafion 117 membrane (2.1 x 10(-6) cm2/s). As a result, the TiO2/bi A-SPAES composite membrane was considered as a promising material for PEM in DMFC.

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.

Composite polymer membranes for proton exchange membrane fuel cells operating at elevated temperatures and reduced humidities

NASA Astrophysics Data System (ADS)

Zhang, Tao

Proton Exchange Membrane Fuel Cells (PEMFCs) are the leading candidate in the fuel cell technology due to the high power density, solid electrolyte, and low operational temperature. However, PEMFCs operating in the normal temperature range (60-80°C) face problems including poor carbon monoxide tolerance and heat rejection. The poisoning effect can be significantly relieved by operating the fuel cell at elevated temperature, which also improves the heat rejection and electrochemical kinetics. Low relative humidity (RH) operation is also desirable to simplify the reactant humidification system. However, at elevated temperatures, reduced RH PEMFC performance is seriously impaired due to irreversible water loss from presently employed state-of-the-art polymer membrane, Nafion. This thesis focuses on developing polymer electrolyte membranes with high water retention ability for operation in elevated temperature (110-150°C), reduced humidity (˜50%RH) PEMFCs. One approach is to alter Nafion by adding inorganic particles such as TiO2, SiO2, Zr(HPO 4)2, etc. While the presence of these materials in Nafion has proven beneficial, a reduction or no improvement in the PEMFC performance of Nafion/TiO2 and Nafion/Zr(HPO4)2 membranes is observed with reduced particle sizes or increased particle loadings in Nafion. It is concluded that the PEMFC performance enhancement associated with addition of these inorganic particles was not due to the particle hydrophilicity. Rather, the particle, partially located in the hydrophobic region of the membrane, benefits the cell performance by altering the membrane structure. Water transport properties of some Nafion composite membranes were investigated by NMR methods including pulsed field gradient spin echo diffusion, spin-lattice relaxation, and spectral measurements. Compared to unmodified Nafion, composite membranes materials exhibit longer longitudinal relaxation time constant T1. In addition to the Nafion material, sulfonated styrene

Steady state and transient simulation of anion exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Dekel, Dario R.; Rasin, Igal G.; Page, Miles; Brandon, Simon

2018-01-01

We present a new model for anion exchange membrane fuel cells. Validation against experimental polarization curve data is obtained for current densities ranging from zero to above 2 A cm-2. Experimental transient data is also successfully reproduced. The model is very flexible and can be used to explore the system's sensitivity to a wide range of material properties, cell design specifications, and operating parameters. We demonstrate the impact of gas inlet relative humidity (RH), operating current density, ionomer loading and ionomer ion exchange capacity (IEC) values on cell performance. In agreement with the literature, high air RH levels are shown to improve cell performance. At high current densities (>1 A cm-2) this effect is observed to be especially significant. Simulated hydration number distributions across the cell reveal the related critical dependence of cathode hydration on air RH and current density values. When exploring catalyst layer design, optimal intermediate ionomer loading values are demonstrated. The benefits of asymmetric (cathode versus anode) electrode design are revealed, showing enhanced performance using higher cathode IEC levels. Finally, electrochemical reaction profiles across the electrodes uncover inhomogeneous catalyst utilization. Specifically, at high current densities the cathodic reaction is confined to a narrow region near the membrane.

Anion-exchange membranes derived from quaternized polysulfone and exfoliated layered double hydroxide for fuel cells

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

Liu, Wan; Liang, Na; Peng, Pai

2017-02-15

Layered double hydroxides (LDH) are prepared by controlling urea assisted homogeneous precipitation conditions. Morphology and crystallinity of LDHs are confirmed by X-ray diffraction and scanning electron microscope. After LDHs are incorporated into quaternized polysulfone membranes, transmission electron microscope is used to observe the exfoliated morphology of LDH sheets in the membranes. The properties of the nanocomposite membranes, including water uptake, swelling ratio, mechanical property and ionic conductivity are investigated. The nanocomposite membrane containing 5% LDH sheets shows more balanced performances, exhibiting an ionic conductivity of 2.36×10{sup −2} S cm{sup −1} at 60 °C. - Graphical abstract: Anion-exchange membrane based onmore » quaternized polysulfone and exfoliated layered double hydroxide is optically transparent and has good ionic properties.« less

Production of Oxygen from Lunar Regolith using Molten Oxide Electrolysis

NASA Technical Reports Server (NTRS)

Sibille, Laurent; Sadoway, Donald R.; Sirk, Aislinn; Tripathy, Prabhat; Melendez, Orlando; Standish, Evan; Dominquez, Jesus A.; Stefanescu, Doru M.; Curreri, Peter A.; Poizeau, Sophie

2009-01-01

This slide presentation reviews the possible use of molten oxide electrolysis to extract oxygen from the Lunar Regolith. The presentation asserts that molten regolith electrolysis has advanced to be a useful method for production of oxygen and metals in situ on the Moon. The work has demonstrated an 8 hour batch of electrolysis at 5 amps using Iridium inert anodes.

Partial oxidation of methane (POM) assisted solid oxide co-electrolysis

DOEpatents

Chen, Fanglin; Wang, Yao

2017-02-21

Methods for simultaneous syngas generation by opposite sides of a solid oxide co-electrolysis cell are provided. The method can comprise exposing a cathode side of the solid oxide co-electrolysis cell to a cathode-side feed stream; supplying electricity to the solid oxide co-electrolysis cell such that the cathode side produces a product stream comprising hydrogen gas and carbon monoxide gas while supplying oxygen ions to an anode side of the solid oxide co-electrolysis cell; and exposing the anode side of the solid oxide co-electrolysis cell to an anode-side feed stream. The cathode-side feed stream comprises water and carbon dioxide, and the anode-side feed stream comprises methane gas such that the methane gas reacts with the oxygen ions to produce hydrogen and carbon monoxide. The cathode-side feed stream can further comprise nitrogen, hydrogen, or a mixture thereof.

Energy efficient reconcentration of diluted human urine using ion exchange membranes in bioelectrochemical systems.

PubMed

Tice, Ryan C; Kim, Younggy

2014-11-01

Nutrients can be recovered from source separated human urine; however, nutrient reconcentration (i.e., volume reduction of collected urine) requires energy-intensive treatment processes, making it practically difficult to utilize human urine. In this study, energy-efficient nutrient reconcentration was demonstrated using ion exchange membranes (IEMs) in a microbial electrolysis cell (MEC) where substrate oxidation at the MEC anode provides energy for the separation of nutrient ions (e.g., NH4(+), HPO4(2-)). The rate of nutrient separation was magnified with increasing number of IEM pairs and electric voltage application (Eap). Ammonia and phosphate were reconcentrated from diluted human urine by a factor of up to 4.5 and 3.0, respectively (Eap = 1.2 V; 3-IEM pairs). The concentrating factor increased with increasing degrees of volume reduction, but it remained stationary when the volume ratio between the diluate (urine solution that is diluted in the IEM stack) and concentrate (urine solution that is reconcentrated) was 6 or greater. The energy requirement normalized by the mass of nutrient reconcentrated was 6.48 MJ/kg-N (1.80 kWh/kg-N) and 117.6 MJ/kg-P (32.7 kWh/kg-P). In addition to nutrient separation, the examined MEC reactor with three IEM pairs showed 54% removal of COD (chemical oxygen demand) in 47-hr batch operation. The high sulfate concentration in human urine resulted in substantial growth of both of acetate-oxidizing and H2-oxidizing sulfate reducing bacteria, greatly diminishing the energy recovery and Coulombic efficiency. However, the high microbial activity of sulfate reducing bacteria hardly affected the rate of nutrient reconcentration. With the capability to reconcentrate nutrients at a minimal energy consumption and simultaneous COD removal, the examined bioelectrochemical treatment method with an IEM application has a potential for practical nutrient recovery and sustainable treatment of source-separated human urine. Copyright © 2014

Zirconium phosphate reinforced short side chain perflurosulfonic acid membranes for medium temperature proton exchange membrane fuel cell application

NASA Astrophysics Data System (ADS)

Casciola, Mario; Cojocaru, Paula; Donnadio, Anna; Giancola, Stefano; Merlo, Luca; Nedellec, Yannig; Pica, Monica; Subianto, Surya

2014-09-01

Composite membranes, made of an 830 equivalent weight short-side-chain perfluorosulfonic acid ionomer and containing up to 10 wt% zirconium phosphate (ZrP), are prepared by casting dispersions of ZrP nanoparticles in the ionomer solution. 30 μm thick composite membranes are characterized by transmission electron microscopy, X-ray diffraction, stress-strain tests, conductivity measurements, water uptake and ion-exchange capacity determinations, as well as fuel cell tests in H2/air. In comparison with the neat ionomer, the tensile modulus (E) and the yield stress (Y) of the composite membranes increase with the ZrP content, both at room temperature (ΔE/E up to +75%, ΔY/Y up to +47%) and at 80 °C/70% relative humidity (ΔE/E up to +64%, ΔY/Y up to +103%). Despite their lower hydration, the composite membranes are as conductive as the neat ionomer and the in-plane conductivity at 110 °C ranges from ∼0.005 S cm-1 at 25% RH to 0.14 S cm-1 at 90% RH. The fuel cell performance of a catalyst coated membrane loaded with 10 wt% ZrP is weakly affected by temperature in the range 80-110 °C. The peak power density decreases from 0.36 W cm-2, at 80 °C, to 0.28 W cm-2 at 110 °C, where the composite membrane performs better than the neat ionomer.

Diffusion-driven proton exchange membrane fuel cell for converting fermenting biomass to electricity.

PubMed

Malati, P; Mehrotra, P; Minoofar, P; Mackie, D M; Sumner, J J; Ganguli, R

2015-10-01

A membrane-integrated proton exchange membrane fuel cell that enables in situ fermentation of sugar to ethanol, diffusion-driven separation of ethanol, and its catalytic oxidation in a single continuous process is reported. The fuel cell consists of a fermentation chamber coupled to a direct ethanol fuel cell. The anode and fermentation chambers are separated by a reverse osmosis (RO) membrane. Ethanol generated from fermented biomass in the fermentation chamber diffuses through the RO membrane into a glucose solution contained in the DEFC anode chamber. The glucose solution is osmotically neutral to the biomass solution in the fermentation chamber preventing the anode chamber from drying out. The fuel cell sustains >1.3 mW cm(-2) at 47°C with high discharge capacity. No separate purification or dilution is necessary, resulting in an efficient and portable system for direct conversion of fermenting biomass to electricity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Energy storage using high pressure electrolysis and methods for reconversion. [in automobile fuel synthesis

NASA Technical Reports Server (NTRS)

Hughes, W. L.

1973-01-01

Theoretical and experimental studies on high pressure electrolysis producing hydrogen and oxygen for energy storage and reconversion are reported. Moderate temperature, high pressure hydrogen/oxygen fuel cells with nickel electrodes are investigated for effects of pressure, temperature, and membrane porosity. Test results from an aphodid burner turbine generator combination obtained 40 percent kilowatt hours out of the fuel cell divided by kilowatt hours into the electrolyzer. It is concluded that high pressure hydrogenation of organic materials can be used to synthesize hydrozenes and methanes for making synthetic vehicular fuels.

Some Aspects of PDC Electrolysis

NASA Astrophysics Data System (ADS)

Poláčik, Ján; Pospíšil, Jiří

2016-10-01

In this paper, aspects of pulsed direct current (PDC) water splitting are described. Electrolysis is a simple and well-known method to produce hydrogen. The efficiency is relatively low in normal conditions using conventional DC. PDC in electrolysis brings about many advantages. It increases efficiency of hydrogen production, and performance of the electrolyser may be smoothly controlled without compromising efficiency of the process. In our approach, ultra-short pulses are applied. This method enhances efficiency of electrical energy in the process of decomposition of water into hydrogen and oxygen. Efficiency depends on frequency, shape and width of the electrical pulses. Experiments proved that efficiency was increased by 2 to 8 per cent. One of the prospects of PDC electrolysis producing hydrogen is in increase of efficiency of energy storage efficiency in the hydrogen. There are strong efforts to make the electrical grid more efficient and balanced in terms of production by installing electricity storage units. Using hydrogen as a fuel decreases air pollution and amount of carbon dioxide emissions in the air. In addition to energy storage, hydrogen is also important in transportation and chemical industry.

Influence of water and membrane microstructure on the transport properties of proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Siu, Ana Rosa

Proton transport in proton exchange membranes (PEMs) depends on interaction between water and acid groups covalently bound to the polymer. Although the presence of water is important in maintaining the PEM's functions, a thorough understanding of this topic is still lacking. The objective of this work is to provide a better understanding of how the nature water, confined to ionic domains of the polymer, influences the membrane's ability to transport protons, methanol and water. Understanding this topic will facilitate development of new materials with favorable transport properties for fuel cells use. Five classes of polymer membranes were used in this work: polyacrylonitrile-graft-poly(styrenesulfonic) acid (PAN-g-macPSSA); poly(vinylidene difluoride) irradiation-graft-poly(styrenesulfonic) acid (PVDF-g-PSSA); poly(ethylenetetrafluoroethylene) irradiation-graft-poly(styrenesulfonic) acid (ETFE-gPSSA); PVDF-g-PSSA with hydroxyethylmethacrylate (HEMA); and perfluorosulfonic acid membrane (Nafion). The nature of water within the polymers (freezable versus non-freezable states) was measured by systematically freezing samples, and observing the temperature at which water freezes and the amount of heat released in the process. Freezing water-swollen membranes resulted in a 4-fold decrease in the proton conductivity of the PEM. Activation energies of proton transport before and after freezing were ˜ 0.15 eV and 0.5 eV, consistent with proton transport through liquid water and bound water, respectively. Reducing the content of water in membrane samples decreased the amount of freezable and non-freezable water. Calorimetric measurements of membranes in various degrees of hydration showed that water molecules became non-freezable when lambda, (water molecules per sulfonic acid group) was less than ˜14. Proton conduction through membranes containing only non-freezable water was demonstrated to be feasible. Diffusion experiments showed that the permeability of methanol

Anion exchange membrane crosslinked in the easiest way stands out for fuel cells

NASA Astrophysics Data System (ADS)

Hossain, Md. Masem; Wu, Liang; Liang, Xian; Yang, Zhengjin; Hou, Jianqiu; Xu, Tongwen

2018-06-01

Covalent crosslinking is an effective method to stabilize anion exchange membranes (AEMs) against water swelling and high alkaline environment, yet complicated process is required. We report herein a straightforward approach to prepare highly crosslinked, transparent and flexible AEM by simply immersing a halo-alkylated polymer (e.g., brominated poly-(2,6-dimethyl-phenylene oxide)) based membrane in aqueous dimethylamine solution at room temperature and the following methylation. During this crosslinking process, a robust self-crosslinking network is formed which shows a gel fraction in N-methyl-2-pyrrolidone of (up to) 94%. Self-crosslinked membranes show low water uptakes (20-42%) and dimensional swelling (9-16%) compared to non-crosslinked membrane but good hydroxide conductivities (up to 26 mS cm-1) at room temperature. Besides, the resulting membranes show some interesting features: the membranes do not immensely change its room temperature water swelling properties at high temperature but exhibits good hydroxide conductivities (up to 60 mS cm-1 at 80 °C). Noting that, the self-crosslinked AEM reported here has no β-hydrogens, exhibiting extremely high alkaline stability (no decline in hydroxide conductivity in 1 M KOH at 60 °C for 360h). Membrane electrode assembly consists of fabricated membrane shows moderate fuel cell performance reaching peak power density 31 mW cm-2 at 60 °C in a H2/O2 alkaline fuel cell.

Investigation of Anion-Exchange and Immunoaffinity Particle-Loaded Membranes for the Isolation of Charged Organic Analytes from Water

USGS Publications Warehouse

Dombrowski, T.R.; Wilson, G.S.; Thurman, E.M.

1998-01-01

Anion-exchange and immunoaffinity particle loaded membranes (PLMs) were investigated as a mechanism for the isolation of charged organic analytes from water. Kinetic properties determined theoretically included dynamic capacity, pressure drop (??P), residence and diffusion times (Tr, Td), and total membrane porosity (???T). These properties were confirmed through experimental evaluation, and the PLM method showed significant improvement over conventional solid-phase extraction (SPE) and ion-exchange formats. Recoveries of more than 90% were observed for a variety of test compounds at flow rates up to 70 mL/min (equipment-limited maximum flow rate). A fast-flow immunoaffinity column was developed using antibodies (Abs) attached to the PLMs. Reproducible recoveries (88% ?? 4%) were observed at flow rates up to 70 mL/min for the antibody (Ab)-loaded PLMs. Findings indicate increased selectivity over anion-exchange PLMs and conventional SPE or ion-exchange methods and rapid Ab-antigen binding rates given the excellent mass-transfer characteristics of the PLMs.

Rechargeable Metal–Air Proton‐Exchange Membrane Batteries for Renewable Energy Storage

PubMed Central

Nagao, Masahiro; Kobayashi, Kazuyo; Yamamoto, Yuta; Yamaguchi, Togo; Oogushi, Akihide

2015-01-01

Abstract Rechargeable proton‐exchange membrane batteries that employ organic chemical hydrides as hydrogen‐storage media have the potential to serve as next‐generation power sources; however, significant challenges remain regarding the improvement of the reversible hydrogen‐storage capacity. Here, we address this challenge through the use of metal‐ion redox couples as energy carriers for battery operation. Carbon, with a suitable degree of crystallinity and surface oxygenation, was used as an effective anode material for the metal redox reactions. A Sn0.9In0.1P2O7‐based electrolyte membrane allowed no crossover of vanadium ions through the membrane. The V4+/V3+, V3+/V2+, and Sn4+/Sn2+ redox reactions took place at a more positive potential than that for hydrogen reduction, so that undesired hydrogen production could be avoided. The resulting electrical capacity reached 306 and 258 mAh g−1 for VOSO4 and SnSO4, respectively, and remained at 76 and 91 % of their respective initial values after 50 cycles. PMID:27525212

Rechargeable Metal-Air Proton-Exchange Membrane Batteries for Renewable Energy Storage.

PubMed

Nagao, Masahiro; Kobayashi, Kazuyo; Yamamoto, Yuta; Yamaguchi, Togo; Oogushi, Akihide; Hibino, Takashi

2016-02-01

Rechargeable proton-exchange membrane batteries that employ organic chemical hydrides as hydrogen-storage media have the potential to serve as next-generation power sources; however, significant challenges remain regarding the improvement of the reversible hydrogen-storage capacity. Here, we address this challenge through the use of metal-ion redox couples as energy carriers for battery operation. Carbon, with a suitable degree of crystallinity and surface oxygenation, was used as an effective anode material for the metal redox reactions. A Sn 0.9 In 0.1 P 2 O 7 -based electrolyte membrane allowed no crossover of vanadium ions through the membrane. The V 4+ /V 3+ , V 3+ /V 2+ , and Sn 4+ /Sn 2+ redox reactions took place at a more positive potential than that for hydrogen reduction, so that undesired hydrogen production could be avoided. The resulting electrical capacity reached 306 and 258 mAh g -1 for VOSO 4 and SnSO 4 , respectively, and remained at 76 and 91 % of their respective initial values after 50 cycles.

Lunar production of oxygen by electrolysis

NASA Technical Reports Server (NTRS)

Keller, Rudolf

1991-01-01

Two approaches to prepare oxygen from lunar resources by direct electrolysis are discussed. Silicates can be melted or dissolved in a fused salt and electrolyzed with oxygen evolved at the anode. Direct melting and electrolysis is potentially a very simple process, but high temperatures of 1400-1500 C are required, which aggravates materials problems. Operating temperatures can be lowered to about 1000 C by employing a molten salt flux. In this case, however, losses of electrolyte components must be avoided. Experimentation on both approaches is progressing.

Microbial desalination cell with sulfonated sodium poly(ether ether ketone) as cation exchange membranes for enhancing power generation and salt reduction.

PubMed

Moruno, Francisco Lopez; Rubio, Juan E; Atanassov, Plamen; Cerrato, José M; Arges, Christopher G; Santoro, Carlo

2018-06-01

Microbial desalination cell (MDC) is a bioelectrochemical system capable of oxidizing organics, generating electricity, while reducing the salinity content of brine streams. As it is designed, anion and cation exchange membranes play an important role on the selective removal of ions from the desalination chamber. In this work, sulfonated sodium (Na + ) poly(ether ether ketone) (SPEEK) cation exchange membranes (CEM) were tested in combination with quaternary ammonium chloride poly(2,6-dimethyl 1,4-phenylene oxide) (QAPPO) anion exchange membrane (AEM). Non-patterned and patterned (varying topographical features) CEMs were investigated and assessed in this work. The results were contrasted against a commercially available CEM. This work used real seawater from the Pacific Ocean in the desalination chamber. The results displayed a high desalination rate and power generation for all the membranes, with a maximum of 78.6±2.0% in salinity reduction and 235±7mWm -2 in power generation for the MDCs with the SPEEK CEM. Desalination rate and power generation achieved are higher with synthesized SPEEK membranes when compared with an available commercial CEM. An optimized combination of these types of membranes substantially improves the performances of MDC, making the system more suitable for real applications. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Quaternized adamantane-containing poly(aryl ether ketone) anion exchange membranes for vanadium redox flow battery applications

NASA Astrophysics Data System (ADS)

Zhang, Bengui; Zhang, Shouhai; Weng, Zhihuan; Wang, Guosheng; Zhang, Enlei; Yu, Ping; Chen, Xiaomeng; Wang, Xinwei

2016-09-01

Quaternized adamantane-containing poly(aryl ether ketone) anion exchange membranes (QADMPEK) are prepared and investigated for vanadium redox flow batteries (VRFB) application. The bulky, rigid and highly hydrophobic adamantane segment incorporated into the backbone of membrane material makes QADMPEK membranes have low water uptake and swelling ratio, and the as-prepared membranes display significantly lower permeability of vanadium ions than that of Nafion117 membrane. As a consequence, the VRFB cell with QADMPEK-3 membrane shows higher coulombic efficiency (99.4%) and energy efficiency (84.0%) than those for Nafion117 membrane (95.2% and 80.5%, respectively) at the current density of 80 mA cm-2. Furthermore, at a much higher current density of 140 mA cm-2, QADMPEK membrane still exhibits better coulombic efficiency and energy efficiency than Nafion117 membrane (coulombic efficiency 99.2% vs 96.5% and energy efficiency 76.0% vs 74.0%). Moreover, QADMPEK membranes show high stability in in-situ VRFB cycle test and ex-situ oxidation stability test. These results indicate that QADMPEK membranes are good candidates for VRFB applications.

Liquid Fuel Production from Biomass via High Temperature Steam Electrolysis

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

Grant L. Hawkes; Michael G. McKellar

2009-11-01

A process model of syngas production using high temperature electrolysis and biomass gasification is presented. Process heat from the biomass gasifier is used to heat steam for the hydrogen production via the high temperature steam electrolysis process. Hydrogen from electrolysis allows a high utilization of the biomass carbon for syngas production. Oxygen produced form the electrolysis process is used to control the oxidation rate in the oxygen-fed biomass gasifier. Based on the gasifier temperature, 94% to 95% of the carbon in the biomass becomes carbon monoxide in the syngas (carbon monoxide and hydrogen). Assuming the thermal efficiency of the powermore » cycle for electricity generation is 50%, (as expected from GEN IV nuclear reactors), the syngas production efficiency ranges from 70% to 73% as the gasifier temperature decreases from 1900 K to 1500 K. Parametric studies of system pressure, biomass moisture content and low temperature alkaline electrolysis are also presented.« less

Electrolysis with diamond anodes: Eventually, there are refractory species!

PubMed

Mena, Ismael F; Cotillas, Salvador; Díaz, Elena; Sáez, Cristina; Rodríguez, Juan J; Cañizares, P; Mohedano, Ángel F; Rodrigo, Manuel A

2018-03-01

In this work, synthetic wastewater polluted with ionic liquid 1-butyl-3-methylimidazolium (Bmim) bis(trifluoromethanesulfonyl)imide (NTf 2 ) undergoes four electrolytic treatments with diamond anodes (bare electrolysis, electrolysis enhanced with peroxosulfate promoters, irradiated with UV light and with US) and results obtained were compared with those obtained with the application of Catalytic Wet Peroxide Oxidation (CWPO). Despite its complex heterocyclic structure, Bmim + cation is successfully depleted with the five technologies tested, being transformed into intermediates that eventually can be mineralized. Photoelectrolysis attained the lowest concentration of intermediates, while CWPO is the technology less efficient in their degradation. However, the most surprising result is that concentration of NTf 2 - anion does not change during the five advanced oxidation processes tested, pointing out its strong refractory character, being the first species that exhibits this character in wastewater undergoing electrolysis with diamond. This means that the hydroxyl and sulfate radicals mediated oxidation and the direct electrolysis are inefficient for breaking the C-S, C-F and S-N bounds of the NTf 2 - anion, which is a very interesting mechanistic information to understand the complex processes undergone in electrolysis with diamond. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel proton exchange membranes based on structure-optimized poly(ether ether ketone ketone)s and nanocrystalline cellulose

NASA Astrophysics Data System (ADS)

Ni, Chuangjiang; Wei, Yingcong; Zhao, Qi; Liu, Baijun; Sun, Zhaoyan; Gu, Yan; Zhang, Mingyao; Hu, Wei

2018-03-01

Two sulfonated fluorenyl-containing poly(ether ether ketone ketone)s (SFPEEKKs) were synthesized as the matrix of composite proton exchange membranes by directly sulfonating copolymer precursors comprising non-sulfonatable fluorinated segments and sulfonatable fluorenyl-containing segments. Surface-modified nanocrystalline cellulose (NCC) was produced as the "performance-enhancing" filler by treating the microcrystalline cellulose with acid. Two families of SFPEEKK/NCC nanocomposite membranes with various NCC contents were prepared via a solution-casting procedure. Results revealed that the insertion of NCC at a suitable ratio could greatly enhance the proton conductivity of the pristine membranes. For example, the proton conductivity of SFPEEKK-60/NCC-4 (SFPEEKK with 60% fluorenyl segments in the repeating unit, and inserted with 4% NCC) composite membrane was as high as 0.245 S cm-1 at 90 °C, which was 61.2% higher than that of the corresponding pure SFPEEKK-60 membrane. This effect could be attributed to the formation of hydrogen bond networks and proton conduction paths through the interaction between -SO3H/-OH groups on the surface of NCC particles and -SO3H groups on the SFPEEKK backbones. Furthermore, the chemically modified NCC filler and the optimized chemical structure of the SFPEEKK matrix also provided good dimensional stability and mechanical properties of the obtained nanocomposites. In conclusion, these novel nanocomposites can be promising proton exchange membranes for fuel cells at moderate temperatures.

A model-based understanding of solid-oxide electrolysis cells (SOECs) for syngas production by H2O/CO2 co-electrolysis

NASA Astrophysics Data System (ADS)

Menon, Vikram; Fu, Qingxi; Janardhanan, Vinod M.; Deutschmann, Olaf

2015-01-01

High temperature co-electrolysis of H2O and CO2 offers a promising route for syngas (H2, CO) production via efficient use of heat and electricity. The performance of a SOEC during co-electrolysis is investigated by focusing on the interactions between transport processes and electrochemical parameters. Electrochemistry at the three-phase boundary is modeled by a modified Butler-Volmer approach that considers H2O electrolysis and CO2 electrolysis, individually, as electrochemically active charge transfer pathways. The model is independent of the geometrical structure. A 42-step elementary heterogeneous reaction mechanism for the thermo-catalytic chemistry in the fuel electrode, the dusty gas model (DGM) to account for multi-component diffusion through porous media, and a plug flow model for flow through the channels are used in the model. Two sets of experimental data are reproduced by the simulations, in order to deduce parameters of the electrochemical model. The influence of micro-structural properties, inlet cathode gas velocity, and temperature are discussed. Reaction flow analysis is performed, at OCV, to study methane production characteristics and kinetics during co-electrolysis. Simulations are carried out for configurations ranging from simple one-dimensional electrochemical button cells to quasi-two-dimensional co-flow planar cells, to demonstrate the effectiveness of the computational tool for performance and design optimization.

Numerical simulation of proton exchange membrane fuel cells at high operating temperature

NASA Astrophysics Data System (ADS)

Peng, Jie; Lee, Seung Jae

A three-dimensional, single-phase, non-isothermal numerical model for proton exchange membrane (PEM) fuel cell at high operating temperature (T ≥ 393 K) was developed and implemented into a computational fluid dynamic (CFD) code. The model accounts for convective and diffusive transport and allows predicting the concentration of species. The heat generated from electrochemical reactions, entropic heat and ohmic heat arising from the electrolyte ionic resistance were considered. The heat transport model was coupled with the electrochemical and mass transport models. The product water was assumed to be vaporous and treated as ideal gas. Water transportation across the membrane was ignored because of its low water electro-osmosis drag force in the polymer polybenzimidazole (PBI) membrane. The results show that the thermal effects strongly affect the fuel cell performance. The current density increases with the increasing of operating temperature. In addition, numerical prediction reveals that the width and distribution of gas channel and current collector land area are key optimization parameters for the cell performance improvement.

Theoretical Studies in Enhancing the Efficiency of Cathode and Anode Materials in PEMFC (Proton Exchange Membrane Fuel Cells)

DTIC Science & Technology

2011-03-04

efficiency of cathode and anode materials in PEMFC (Proton Exchange Membrane Fuel Cells) 5a. CONTRACT NUMBER FA23861014012 5b. GRANT NUMBER 5c. PROGRAM...Rev. 8-98) Prescribed by ANSI Std Z39-18 Theoretical studies in enhancing the efficiency of cathode and anode materials in PEMFC (Proton Exchange

Technology advancement of the static feed water electrolysis process

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Wynveen, R. A.

1977-01-01

A program to advance the technology of oxygen- and hydrogen-generating subsystems based on water electrolysis was studied. Major emphasis was placed on static feed water electrolysis, a concept characterized by low power consumption and high intrinsic reliability. The static feed based oxygen generation subsystem consists basically of three subassemblies: (1) a combined water electrolysis and product gas dehumidifier module; (2) a product gas pressure controller and; (3) a cyclically filled water feed tank. Development activities were completed at the subsystem as well as at the component level. An extensive test program including single cell, subsystem and integrated system testing was completed with the required test support accessories designed, fabricated, and assembled. Mini-product assurance activities were included throughout all phases of program activities. An extensive number of supporting technology studies were conducted to advance the technology base of the static feed water electrolysis process and to resolve problems.

Cathode Wetting Studies in Magnesium Electrolysis

NASA Astrophysics Data System (ADS)

McLean, Kevin; Pettingill, James; Davis, Boyd

The effects of cathode materials and electrolyte additives on magnesium wetting were studied with the goal of improving current efficiency in a magnesium electrolysis cell. The study consisted of static wetting and electrolysis tests, both conducted in a visual cell with a molten salt electrolyte of MgCl2-CaCl2-NaCl-KCl-CaF2. The wetting conditions were tested using high resolution photography and contact angle software. The electrolysis tests were completed to qualitatively assess the effect of additives to the melt and were recorded with a digital video camcorder. Results from the static wetting tests showed a significant variation in wetting depending on the material used for the cathode. Mo and a Mo-W alloy, with contact angles of 60° and 52° respectively, demonstrated excellent wetting. The contact angle for steel was 132° and it ranged from 142°-154° for graphite depending on the type. Improvements to the cathode wetting were observed with tungsten and molybdenum oxide additives.

Progress in Aluminum Electrolysis Control and Future Direction for Smart Aluminum Electrolysis Plant

NASA Astrophysics Data System (ADS)

Zhang, Hongliang; Li, Tianshuang; Li, Jie; Yang, Shuai; Zou, Zhong

2017-02-01

The industrial aluminum reduction cell is an electrochemistry reactor that operates under high temperatures and highly corrosive conditions. However, these conditions have restricted the measurement of key control parameters, making the control of aluminum reduction cells a difficult problem in the industry. Because aluminum electrolysis control systems have a significant economic influence, substantial research has been conducted on control algorithms, control systems and information systems for aluminum reduction cells. This article first summarizes the development of control systems and then focuses on the progress made since 2000, including alumina concentration control, temperature control and electrolyte molecular ratio control, fault diagnosis, cell condition prediction and control system expansion. Based on these studies, the concept of a smart aluminum electrolysis plant is proposed. The frame construction, key problems and current progress are introduced. Finally, several future directions are discussed.

Electrolysis treatment of trichiasis by using ultra-fine needle.

PubMed

Sakarya, Yasar; Sakarya, Rabia; Yildirim, Aydin

2010-01-01

To determine the safety and efficacy of electrolysis treatment of trichiasis by using ultrafine needle. The medical records of 24 lids of 24 patients who underwent electrolysis treatment for trichiasis by the same surgeon (Y.S.) during the period from May 2006 through December 2008 were reviewed. The average age of the 24 patients was 59.2 years (range, 43 to 76 years). Thirteen of the patients were women. The results were considered satisfactory if no recurrence of trichiasis occurred for at least 6 months after the last electrolysis procedure. Sixteen of the 24 patients (66.6%) had a satisfactory result with 1 treatment. Of the 8 patients (33.3%) who had an unsatisfactory result, while 5 (20.8%) responded well to 1 additional electrolysis, 3 (12.5%) responded well to 2 additional electrolyses to the recurrent cilia. The procedure was well tolerated by the patients. All eyelids healed within 2 weeks after treatment without any scarring. Faint hypopigmentation was visible in 2 patients (8.3%). Mild notching of eyelid occurred in 4 patients (16.6%). Electrolysis treatment by using ultrafine (55-microm thickness) needle is an effective and safe method for treatment of trichiasis with many advantages over other recognized modalities of therapy.

Ion exchange membranes as novel passive sampling material for organic ions: application for the determination of freely dissolved concentrations.

PubMed

Oemisch, Luise; Goss, Kai-Uwe; Endo, Satoshi

2014-11-28

Many studies in pharmacology, toxicology and environmental science require a method for determining the freely dissolved concentration of a target substance. A recently developed tool for this purpose is equilibrium passive sampling with polymeric materials. However, this method has rarely been applied to ionic organic substances, primarily due to limited availability of convenient sorption materials. This study introduces ion exchange membranes (IEMs) as a novel passive sampling material for organic ions. The partitioning of 4-ethylbenzene-1-sulfonate, 2,4-dichlorophenoxyacetic acid and pentachlorophenol to one anion exchange membrane (FAS) and of difenzoquat, nicotine and verapamil to one cation exchange membrane (FKS) was investigated. All test substances exhibited a sufficiently high affinity for the respective IEM with logarithmic IEM-water partition coefficients >2.3. Sorption equilibrium was established quickly, within several hours for the FAS membrane and within 1-3 days for the FKS membrane. For permanently charged substances the partitioning to the IEMs was independent of pH, but was influenced by the salt composition of the test solution. For all test substances sorption to IEM was dependent on the substance concentration. Bovine serum albumin-water partition coefficients determined by passive sampling with IEMs agree well with those determined by the conventional dialysis method. The results of this study indicate that IEMs exhibit the potential to measure freely dissolved concentrations of organic ions in a simple and time-saving manner. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of glucose exchange rates and permeability of erythrocyte membrane in preeclampsia and subsequent oxidative stress-related protein damage using dynamic-19F-NMR.

PubMed

Dickinson, Elizabeth; Arnold, John R P; Fisher, Julie

2017-02-01

The cause of the pregnancy condition preeclampsia (PE) is thought to be endothelial dysfunction caused by oxidative stress. As abnormal glucose tolerance has also been associated with PE, we use a fluorinated-mimic of this metabolite to establish whether any oxidative damage to lipids and proteins in the erythrocyte membrane has increased cell membrane permeability. Data were acquired using 19 F Dynamic-NMR (DNMR) to measure exchange of 3-fluoro-3-deoxyglucose (3-FDG) across the membrane of erythrocytes from 10 pregnant women (5 healthy control women, and 5 from women suffering from PE). Magnetisation transfer was measured using the 1D selective inversion and 2D EXSY pulse sequences, over a range of time delays. Integrated intensities from these experiments were used in matrix diagonalisation to estimate the values of the rate constants of exchange and membrane permeability. No significant differences were observed for the rate of exchange of 3-FDG and membrane permeability between healthy pregnant women and those suffering from PE, leading us to conclude that no oxidative damage had occurred at this carrier-protein site in the membrane.

Proton exchange membrane fuel cell technology for transportation applications

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

Swathirajan, S.

1996-04-01

Proton Exchange Membrane (PEM) fuel cells are extremely promising as future power plants in the transportation sector to achieve an increase in energy efficiency and eliminate environmental pollution due to vehicles. GM is currently involved in a multiphase program with the US Department of Energy for developing a proof-of-concept hybrid vehicle based on a PEM fuel cell power plant and a methanol fuel processor. Other participants in the program are Los Alamos National Labs, Dow Chemical Co., Ballard Power Systems and DuPont Co., In the just completed phase 1 of the program, a 10 kW PEM fuel cell power plantmore » was built and tested to demonstrate the feasibility of integrating a methanol fuel processor with a PEM fuel cell stack. However, the fuel cell power plant must overcome stiff technical and economic challenges before it can be commercialized for light duty vehicle applications. Progress achieved in phase I on the use of monolithic catalyst reactors in the fuel processor, managing CO impurity in the fuel cell stack, low-cost electrode-membrane assembles, and on the integration of the fuel processor with a Ballard PEM fuel cell stack will be presented.« less

Pendant dual sulfonated poly(arylene ether ketone) proton exchange membranes for fuel cell application

NASA Astrophysics Data System (ADS)

Nguyen, Minh Dat Thinh; Yang, Sungwoo; Kim, Dukjoon

2016-10-01

Poly(arylene ether ketone) (PAEK) possessing carboxylic groups at the pendant position is synthesized, and the substitution degree of pendant carboxylic groups is controlled by adjusting the ratio of 4,4-bis(4-hydroxyphenyl)valeric acid and 2,2-bis(4-hydroxyphenyl)propane. Dual sulfonated 3,3-diphenylpropylamine (SDPA) is grafted onto PAEK as a proton-conducting moiety via the amidation reaction with carboxylic groups. The transparent and flexible membranes with different degrees of sulfonation are fabricated so that we can test and compare their structure and properties with a commercial Nafion® 115 membrane for PEMFC applications. All prepared PAEK-SDPA membranes exhibit good oxidative and hydrolytic stability from Fenton's and high temperature water immersion test. SAXS analysis illustrates an excellent phase separation between the hydrophobic backbone and hydrophilic pendant groups, resulting in big ionic clusters. The proton conductivity was measured at different relative humidity, and its behavior was analyzed by hydration number of the membrane. Among a series of membranes, some samples (including B20V80-SDPA) show not only higher proton conductivity, but also higher integrated cell performance than those of Nafion® 115 at 100% relative humidity, and thus we expect these to be good candidate membranes for proton exchange membrane fuel cells (PEMFCs).

High Temperature Steam Electrolysis: Demonstration of Improved Long-Term Performance

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

J. E. O'Brien; X. Zhang; R. C. O'Brien

2011-11-01

Long-term performance is an ongoing issue for hydrogen production based on high-temperature steam electrolysis (HTSE). For commercial deployment, solid-oxide electrolysis stacks must achieve high performance with long-term degradation rates of {approx}0.5%/1000 hours or lower. Significant progress has been achieved toward this goal over the past few years. This paper will provide details of progress achieved under the Idaho National Laboratory high temperature electrolysis research program. Recent long-term stack tests have achieved high initial performance with degradation rates less than 5%/khr. These tests utilize internally manifolded stacks with electrode-supported cells. The cell material sets are optimized for the electrolysis mode ofmore » operation. Details of the cells and stacks will be provided along with details of the test apparatus, procedures, and results.« less

Electrolysis Apparatus and a Method of Hydrodynamic Cavitation Protection.

DTIC Science & Technology

1974-09-17

AD-DO01 178 ELECTROLYSIS APPARATUS AND A METHOD OF HYDRODYNAMIC CAVITATION PROTECTION Earl Quandt, et al Department of the Navy Washington, D. C. 17...213" 261123 , Navy Case No. 57,238 ELECTROLYSIS APPARATUS AND A METHOD OF HYDRODYNAMIC CAVITATION PROTECTION 1 ABSTRACT Method of and apparatus for

Heterogeneous structure and its effect on properties and electrochemical behavior of ion-exchange membrane

NASA Astrophysics Data System (ADS)

Ariono, D.; Khoiruddin; Subagjo; Wenten, I. G.

2017-02-01

Generally, commercially available ion-exchange membrane (IEM) can be classified into homogeneous and heterogeneous membranes. The classification is based on degree of heterogeneity in membrane structure. It is well known that the heterogeneity greatly affects the properties of IEM, such as conductivity, permselectivity, chemical and mechanical stability. The heterogeneity also influences ionic and electrical current transfer behavior of IEM-based processes during their operation. Therefore, understanding the role of heterogeneity in IEM properties is important to provide preliminary information on their operability and applicability. In this paper, the heterogeneity and its effect on IEM properties are reviewed. Some models for describing the heterogeneity of IEM and methods for characterizing the degree of heterogeneity are discussed. In addition, the influence of heterogeneity on the performance of IEM-based processes and their electrochemical behavior are described.

Mechanism of charged pollutants removal in an ion exchange membrane bioreactor: drinking water denitrification.

PubMed

Velizarov, S; Rodrigues, C M; Reis, M A; Crespo, J G

The mechanism of anionic pollutant removal in an ion exchange membrane bioreactor (IEMB) was studied for drinking water denitrification. This hybrid process combines continuous ion exchange transport (Donnan dialysis) of nitrate and its simultaneous bioreduction to gaseous nitrogen. A nonporous mono-anion permselective membrane precludes direct contact between the polluted water and the denitrifying culture and prevents secondary pollution of the treated water with dissolved nutrients and metabolic products. Complete denitrification may be achieved without accumulation of NO3(-) and NO2(-) ions in the biocompartment. Focus was given to the effect of the concentration of co-ions, counterions, and ethanol on the IEMB performance. The nitrate overall mass transfer coefficient in this hybrid process was found to be 2.8 times higher compared to that in a pure Donnan dialysis process without denitrification. Furthermore, by adjusting the ratio of co-ions between the biocompartment and the polluted water compartment, the magnitude and direction of each individual anion flux can be easily regulated, allowing for flexible process operation and control. Synthetic groundwater containing 135-350 mg NO3(-) L(-1) was treated in the IEMB system. A surface denitrification rate of 33 g NO3(-) per square meter of membrane per day was obtained at a nitrate loading rate of 360 g NO3(-) m(-3)d(-1), resulting in a nitrate removal efficiency of 85%.

Gadolinia-Doped Ceria Cathodes for Electrolysis of CO2

NASA Technical Reports Server (NTRS)

Adler, Stuart B.

2009-01-01

Gadolinia-doped ceria, or GDC, (Gd(0.4)Ce(0.6)O(2-delta), where the value of delta in this material varies, depending on the temperature and oxygen concentration in the atmosphere in which it is being used) has shown promise as a cathode material for high-temperature electrolysis of carbon dioxide in solid oxide electrolysis cells. The polarization resistance of a GDC electrode is significantly less than that of an otherwise equivalent electrode made of any of several other materials that are now in use or under consideration for use as cathodes for reduction of carbon dioxide. In addition, GDC shows no sign of deterioration under typical temperature and gas-mixture operating conditions of a high-temperature electrolyzer. Electrolysis of CO2 is of interest to NASA as a way of generating O2 from the CO2 in the Martian atmosphere. On Earth, a combination of electrolysis of CO2 and electrolysis of H2O might prove useful as a means of generating synthesis gas (syngas) from the exhaust gas of a coal- or natural-gas-fired power plant, thereby reducing the emission of CO2 into the atmosphere. The syngas a mixture of CO and H2 could be used as a raw material in the manufacture, via the Fisher-Tropsch process, of synthetic fuels, lubrication oils, and other hydrocarbon prod

Oxygen-consuming chlor alkali cell configured to minimize peroxide formation

DOEpatents

Chlistunoff, Jerzy B [Los Alamos, NM; Lipp, Ludwig [Brookfield, CT; Gottesfeld, Shimshon [Niskayuna, NY

2006-08-01

Oxygen-consuming zero gap chlor-alkali cell was configured to minimize peroxide formation. The cell included an ion-exchange membrane that divided the cell into an anode chamber including an anode and a cathode chamber including an oxygen gas diffusion cathode. The cathode included a single-piece of electrically conducting graphitized carbon cloth. Catalyst and polytetrafluoroethylene were attached to only one side of the cloth. When the cathode was positioned against the cation exchange membrane with the catalyst side away from the membrane, electrolysis of sodium chloride to chlorine and caustic (sodium hydroxide) proceeded with minimal peroxide formation.

A series of poly(butylimidazolium) ionic liquid functionalized copolymers for anion exchange membranes

NASA Astrophysics Data System (ADS)

Ouadah, Amina; Xu, Hulin; Luo, Tianwei; Gao, Shuitao; Wang, Xing; Fang, Zhou; Jing, Chaojun; Zhu, Changjin

2017-12-01

A new series of ionic liquid functionalized copolymers for anion exchange membranes (AEM) is prepared. Poly(butylvinylimidazolium)(b-VIB) is copolymerized with para-methyl styrene (p-MS) by the radical polymerization formed block copolymers b-VIB/p-MS, which is crosslinked with poly(diphenylether bibenzimidazole) (DPEBI) providing the desired materials b-VIB/p-MS/DPEBI. Structures are characterized via H1NMR, FTIR spectra and elemental analysis. The b-VIB blocks offer the anion conduction function while DPEBI moieties contribute to enhancing other properties. The prepared membranes display chloride conductivity as high as 19.5 mS/cm at 25 °C and 69.2 mS/cm at 100 °C-higher than that of the commercial membrane tokuyuama A201-. Their hydroxide conductivity reaches 35.7 Scm-1 at 25 °C and 73.1 Scm-1 at 100 °C. The membranes showed a linear Arrhenius behavior in the anion conduction, low activation energies and distinguished nanophase separation of hydrophilic/hydrophobic regions by the transmission electron microscopy (TEM) studies. Thermal investigations using TGA and DSC confirm that the membranes are stable up to 250 °C. Particularly, drastically alkaline stability due to no decrease in the hydroxide conductivity after 168 h of treatment with 2M KOH.

Modeling and simulation of anion-exchange membrane chromatography for purification of Sf9 insect cell-derived virus-like particles.

PubMed

Ladd Effio, Christopher; Hahn, Tobias; Seiler, Julia; Oelmeier, Stefan A; Asen, Iris; Silberer, Christine; Villain, Louis; Hubbuch, Jürgen

2016-01-15

Recombinant protein-based virus-like particles (VLPs) are steadily gaining in importance as innovative vaccines against cancer and infectious diseases. Multiple VLPs are currently evaluated in clinical phases requiring a straightforward and rational process design. To date, there is no generic platform process available for the purification of VLPs. In order to accelerate and simplify VLP downstream processing, there is a demand for novel development approaches, technologies, and purification tools. Membrane adsorbers have been identified as promising stationary phases for the processing of bionanoparticles due to their large pore sizes. In this work, we present the potential of two strategies for designing VLP processes following the basic tenet of 'quality by design': High-throughput experimentation and process modeling of an anion-exchange membrane capture step. Automated membrane screenings allowed the identification of optimal VLP binding conditions yielding a dynamic binding capacity of 5.7 mg/mL for human B19 parvovirus-like particles derived from Spodoptera frugiperda Sf9 insect cells. A mechanistic approach was implemented for radial ion-exchange membrane chromatography using the lumped-rate model and stoichiometric displacement model for the in silico optimization of a VLP capture step. For the first time, process modeling enabled the in silico design of a selective, robust and scalable process with minimal experimental effort for a complex VLP feedstock. The optimized anion-exchange membrane chromatography process resulted in a protein purity of 81.5%, a DNA clearance of 99.2%, and a VLP recovery of 59%. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of gaseous oxidized Hg measured by KCl-coated denuders, and nylon and cation exchange membranes.

PubMed

Huang, Jiaoyan; Miller, Matthieu B; Weiss-Penzias, Peter; Gustin, Mae Sexauer

2013-07-02

The chemical compounds that make up gaseous oxidized mercury (GOM) in the atmosphere, and the reactions responsible for their formation, are not well understood. The limitations and uncertainties associated with the current method applied to measure these compounds, the KCl-coated denuder, are not known due to lack of calibration and testing. This study systematically compared the uptake of specific GOM compounds by KCl-coated denuders with that collected using nylon and cation exchange membranes in the laboratory and field. In addition, a new method for identifying different GOM compounds using thermal desorption is presented. Different GOM compounds (HgCl2, HgBr2, and HgO) were found to have different affinities for the denuder surface and the denuder underestimated each of these compounds. Membranes measured 1.3 to 3.7 times higher GOM than denuders in laboratory and field experiments. Cation exchange membranes had the highest collection efficiency. Thermodesorption profiles for the release of GOM compounds from the nylon membrane were different for HgO versus HgBr2 and HgCl2. Application of the new field method for collection and identification of GOM compounds demonstrated these vary as a function of location and time of year. Understanding the chemistry of GOM across space and time has important implications for those developing policy regarding this environmental contaminant.

Nanoscale current imaging of the conducting channels in proton exchange membrane fuel cells.

PubMed

Bussian, David A; O'Dea, James R; Metiu, Horia; Buratto, Steven K

2007-02-01

The electrochemically active area of a proton exchange membrane fuel cell (PEMFC) is investigated using conductive probe atomic force microscopy (CP-AFM). A platinum-coated AFM tip is used as a nanoscale cathode in an operating PEMFC. We present results that show highly inhomogeneous distributions of conductive surface domains at several length scales. At length scales on the order of the aqueous domains of the membrane, approximately 50 nm, we observe single channel electrochemistry. I-V curves for single conducting channels are obtained, which yield insight into the nature of conductive regions across the PEM. In addition, we demonstrate a new characterization technique, phase current correlation microscopy, which gives a direct measure of the electrochemical activity for each aqueous domain. This shows that a large number ( approximately 60%) of the aqueous domains present at the surface of an operating Nafion membrane are inactive. We attribute this to a combination of limited aqueous domain connectivity and catalyst accessibility.

Comparing the short and long term stability of biodegradable, ceramic and cation exchange membranes in microbial fuel cells.

PubMed

Winfield, Jonathan; Chambers, Lily D; Rossiter, Jonathan; Ieropoulos, Ioannis

2013-11-01

The long and short-term stability of two porous dependent ion exchange materials; starch-based compostable bags (BioBag) and ceramic, were compared to commercially available cation exchange membrane (CEM) in microbial fuel cells. Using bi-directional polarisation methods, CEM exhibited power overshoot during the forward sweep followed by significant power decline over the reverse sweep (38%). The porous membranes displayed no power overshoot with comparably smaller drops in power during the reverse sweep (ceramic 8%, BioBag 5.5%). The total internal resistance at maximum power increased by 64% for CEM compared to 4% (ceramic) and 6% (BioBag). Under fixed external resistive loads, CEM exhibited steeper pH reductions than the porous membranes. Despite its limited lifetime, the BioBag proved an efficient material for a stable microbial environment until failing after 8 months, due to natural degradation. These findings highlight porous separators as ideal candidates for advancing MFC technology in terms of cost and operation stability. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of glycidyl methacrylate (GMA) incorporation on water uptake and conductivity of proton exchange membranes

NASA Astrophysics Data System (ADS)

Sproll, Véronique; Schmidt, Thomas J.; Gubler, Lorenz

2018-03-01

The aim of this work was to investigate how hygroscopic moieties like hydrolyzed glycidyl methacrylate (GMA) influence the properties of sulfonated polysytrene based proton exchange membranes (PEM). Therefore, several membranes were synthesized by electron beam treatment of the ETFE (ethylene-alt-tetrafluoroethylene) base film with a subsequent co-grafting of styrene and GMA at different ratios. The obtained membranes were sulfonated to introduce proton conducting groups and the epoxide moiety of the GMA unit was hydrolyzed for a better water absorption. The PEM was investigated regarding its structural composition, water uptake and through-plane conductivity. It could be shown that the density of sulfonic acid groups has a higher influence on the proton conductivity of the PEM than an increased water uptake.

Synergistic Combination of Electrolysis and Electroporation for Tissue Ablation.

PubMed

Stehling, Michael K; Guenther, Enric; Mikus, Paul; Klein, Nina; Rubinsky, Liel; Rubinsky, Boris

2016-01-01

Electrolysis, electrochemotherapy with reversible electroporation, nanosecond pulsed electric fields and irreversible electroporation are valuable non-thermal electricity based tissue ablation technologies. This paper reports results from the first large animal study of a new non-thermal tissue ablation technology that employs "Synergistic electrolysis and electroporation" (SEE). The goal of this pre-clinical study is to expand on earlier studies with small animals and use the pig liver to establish SEE treatment parameters of clinical utility. We examined two SEE methods. One of the methods employs multiple electrochemotherapy-type reversible electroporation magnitude pulses, designed in such a way that the charge delivered during the electroporation pulses generates the electrolytic products. The second SEE method combines the delivery of a small number of electrochemotherapy magnitude electroporation pulses with a low voltage electrolysis generating DC current in three different ways. We show that both methods can produce lesion with dimensions of clinical utility, without the need to inject drugs as in electrochemotherapy, faster than with conventional electrolysis and with lower electric fields than irreversible electroporation and nanosecond pulsed ablation.

Synergistic Combination of Electrolysis and Electroporation for Tissue Ablation

PubMed Central

Mikus, Paul; Klein, Nina; Rubinsky, Liel; Rubinsky, Boris

2016-01-01

Electrolysis, electrochemotherapy with reversible electroporation, nanosecond pulsed electric fields and irreversible electroporation are valuable non-thermal electricity based tissue ablation technologies. This paper reports results from the first large animal study of a new non-thermal tissue ablation technology that employs “Synergistic electrolysis and electroporation” (SEE). The goal of this pre-clinical study is to expand on earlier studies with small animals and use the pig liver to establish SEE treatment parameters of clinical utility. We examined two SEE methods. One of the methods employs multiple electrochemotherapy-type reversible electroporation magnitude pulses, designed in such a way that the charge delivered during the electroporation pulses generates the electrolytic products. The second SEE method combines the delivery of a small number of electrochemotherapy magnitude electroporation pulses with a low voltage electrolysis generating DC current in three different ways. We show that both methods can produce lesion with dimensions of clinical utility, without the need to inject drugs as in electrochemotherapy, faster than with conventional electrolysis and with lower electric fields than irreversible electroporation and nanosecond pulsed ablation. PMID:26866693

Measuring the equation of state for a 2D colloidal membrane: A microfluidic approach to buffer exchange

NASA Astrophysics Data System (ADS)

Balchunas, Andrew; Cabanas, Rafael; Fraden, Seth; Dogic, Zvonimir

Previous work has shown that monodisperse rod-like colloidal particles, such as a filamentous bacteriophage, self assemble into a 2D monolayer smectic in the presence of a non-adsorbing depleting polymer. These structures have the same functional form of bending rigidity and lateral compressibility as conventional lipid bi-layers, so we name the monolayer smectic a colloidal membrane. We have developed a microfluidic device such that the osmotic pressure acting on a colloidal membrane may be controlled via a full in situ buffer exchange. Rod density within individual colloidal membranes was measured as a function of osmotic pressure and a first order phase transition, from 2D fluid to 2D solid, was observed. kon and koff rates of rod to membrane binding were measured by lowering the osmotic pressure until membrane evaporation occurred.

Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes

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

He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T.

2011-08-01

The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationshipmore » between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.« less

Electrical Impedance Tomography of Electrolysis

PubMed Central

Meir, Arie; Rubinsky, Boris

2015-01-01

The primary goal of this study is to explore the hypothesis that changes in pH during electrolysis can be detected with Electrical Impedance Tomography (EIT). The study has relevance to real time control of minimally invasive surgery with electrolytic ablation. To investigate the hypothesis, we compare EIT reconstructed images to optical images acquired using pH-sensitive dyes embedded in a physiological saline agar gel phantom treated with electrolysis. We further demonstrate the biological relevance of our work using a bacterial E.Coli model, grown on the phantom. The results demonstrate the ability of EIT to image pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E.coli model. The results are promising, and invite further experimental explorations. PMID:26039686

Electrolysis of simulated lunar melts

NASA Technical Reports Server (NTRS)

Lewis, R. H.; Lindstrom, D. J.; Haskin, L. A.

1985-01-01

Electrolysis of molten lunar soil or rock is examined as an attractive means of wresting useful raw materials from lunar rocks. It requires only hat to melt the soil or rock and electricity to electrolyze it, and both can be developed from solar power. The conductivities of the simple silicate diopside, Mg CaSi2O6 were measured. Iron oxide was added to determine the effect on conductivity. The iron brought about substantial electronic conduction. The conductivities of simulated lunar lavas were measured. The simulated basalt had an AC conductivity nearly a fctor of two higher than that of diopside, reflecting the basalt's slightly higher total concentration of the 2+ ions Ca, Mg, and Fe that are the dominant charge carriers. Electrolysis was shown to be about 30% efficient for the basalt composition.

Three-Man Solid Electrolyte Carbon Dioxide Electrolysis Breadboard

NASA Technical Reports Server (NTRS)

Isenberg, Arnold O.

1989-01-01

The development of the Three-Man (2.2 lb CO2/man-day) Solid Electrolyte CO2 Electrolysis Breadboard consisted of a Phase 1 and 2 effort. The Phase 1 effort constituted fabrication of three electrolysis cell types and performing parametric testing, off-design testing, and cell life testing. The Phase 2 consisted of the preliminary design, incorporation of palladium (Pd) tubes for hydrogen separation from the electrolyzer cathode feed gases, design support testing, final design, fabrication, and performance testing of the breadboard system. The results of performance tests demonstrated that CO2 electrolysis in an oxygen reclamation system for long duration space-based habitats is feasible. Closure of the oxygen system loop, therefore, can be achieved by CO2 electrolysis. In a two step process the metabolic CO2 and H2O vapor are electrolyzed into O2, H2, and CO. The CO can subsequently be disproportionated into carbon and CO2 in a carbon deposition reactor and the CO2 in turn be recycled and electrolyzed for total O2 recovery. The development effort demonstrated electrolyzer system can be designed and built to operate safely and reliably and the incorporation of Pd tubes for hydrogen diffusion can be integrated safely with predictable performance.

Sliding mode observer for proton exchange membrane fuel cell: automotive application

NASA Astrophysics Data System (ADS)

Piffard, Maxime; Gerard, Mathias; Fonseca, Ramon Da; Massioni, Paolo; Bideaux, Eric

2018-06-01

This work proposes a state observer as a tool to manage cost and durability issues for PEMFC (Proton Exchange Membrane Fuel Cell) in automotive applications. Based on a dead-end anode architecture, the observer estimates the nitrogen build-up in the anode side, as well as relative humidities in the channels. These estimated parameters can then be used at fuel cell management level to enhance the durability of the stack. This observer is based on transport equations through the membrane and it reconstructs the behavior of the water and nitrogen inside the channels without the need of additional humidity sensors to correct the estimate. The convergence of the output variables is proved with Lyapunov theory for dynamic operating conditions. The validation is made with a high-fidelity model running a WLTC (Worldwide harmonized Light vehicles Test Cycle). This observer provides the average values of nitrogen and relative humidities with sufficient precision to be used in a global real-time control scheme.

Fatigue and creep to leak tests of proton exchange membranes using pressure-loaded blisters

NASA Astrophysics Data System (ADS)

Li, Yongqiang; Dillard, David A.; Case, Scott W.; Ellis, Michael W.; Lai, Yeh-Hung; Gittleman, Craig S.; Miller, Daniel P.

In this study, three commercially available proton exchange membranes (PEMs) are biaxially tested using pressure-loaded blisters to characterize their resistance to gas leakage under either static (creep) or cyclic fatigue loading. The pressurizing medium, air, is directly used for leak detection. These tests are believed to be more relevant to fuel cell applications than quasi-static uniaxial tensile-to-rupture tests because of the use of biaxial cyclic and sustained loading and the use of gas leakage as the failure criterion. They also have advantages over relative humidity cycling test, in which a bare PEM or catalyst coated membrane is clamped with gas diffusion media and flow field plates and subjected to cyclic changes in relative humidity, because of the flexibility in allowing controlled mechanical loading and accelerated testing. Nafion ® NRE-211 membranes are tested at three different temperatures and the time-temperature superposition principle is used to construct stress-lifetime master curve. Tested at 90 °C, 2%RH extruded Ion Power ® N111-IP membranes have a longer lifetime than Gore™-Select ® 57 and Nafion ® NRE-211 membranes.

Development status of a preprototype water electrolysis subsystem

NASA Technical Reports Server (NTRS)

Martin, R. B.; Erickson, A. C.

1981-01-01

A preprototype water electrolysis subsystem was designed and fabricated for NASA's advanced regenerative life support program. A solid polymer is used for the cell electrolyte. The electrolysis module has 12 cells that can generate 5.5 kg/day of oxygen for the metabolic requirements of three crewmembers, for cabin leakage, and for the oxygen and hydrogen required for carbon dioxide collection and reduction processes. The subsystem can be operated at a pressure between 276 and 2760 kN/sq m and in a continuous constant-current, cyclic, or standby mode. A microprocessor is used to aid in operating the subsystem. Sensors and controls provide fault detection and automatic shutdown. The results of development, demonstration, and parametric testing are presented. Modifications to enhance operation in an integrated and manned test are described. Prospective improvements for the electrolysis subsystem are discussed.

Steam electrolysis by solid oxide electrolysis cells (SOECs) with proton-conducting oxides.

PubMed

Bi, Lei; Boulfrad, Samir; Traversa, Enrico

2014-12-21

Energy crisis and environmental problems caused by the conventional combustion of fossil fuels boost the development of renewable and sustainable energies. H2 is regarded as a clean fuel for many applications and it also serves as an energy carrier for many renewable energy sources, such as solar and wind power. Among all the technologies for H2 production, steam electrolysis by solid oxide electrolysis cells (SOECs) has attracted much attention due to its high efficiency and low environmental impact, provided that the needed electrical power is generated from renewable sources. However, the deployment of SOECs based on conventional oxygen-ion conductors is limited by several issues, such as high operating temperature, hydrogen purification from water, and electrode stability. To avoid these problems, proton-conducting oxides are proposed as electrolyte materials for SOECs. This review paper provides a broad overview of the research progresses made for proton-conducting SOECs, summarizing the past work and finding the problems for the development of proton-conducting SOECs, as well as pointing out potential development directions.

Asymmetric electroosmotic pumping across porous media sandwiched with perforated ion-exchange membranes.

PubMed

Yaroshchuk, A; Licón, E E; Zholkovskiy, E K; Bondarenko, M P; Heldal, T

2017-07-01

To have non-zero net flow in AC electroosmotic pumps, the electroosmosis (EO) has to be non-linear and asymmetric. This can be achieved due to ionic concentration polarization. This is known to occur close to micro-/nano-interfaces provided that the sizes of the nanopores are not too large compared to the Debye screening length. However, operation of the corresponding EO pumps can be quite sensitive to the solution concentration and, thus, unstable in practical applications. Concentration polarization of ion-exchange membranes is much more robust. However, the hydraulic permeability of the membrane is very low, which makes EO flows through them extremely small. This communication shows theoretically how this problem can be resolved via making scarce microscopic perforations in an ion-exchange membrane and putting it in series with an EO-active nano-porous medium. The problem of coupled flow, concentration and electrostatic-potential distributions is solved numerically by using finite-element methods. This analysis reveals that even quite scarce perforations of micron-scale diameters are sufficient to observe practically-interesting EO flows in the system. If the average distance between the perforations is smaller than the thickness of the EO-active layer, there is an effective homogenization of the electrolyte concentration and hydrostatic pressure in the lateral direction at some distance from the interface. The simulations show this distance to be somewhat lower than the half-distance between the perforations. On the other hand, when the surface fraction of perforations is sufficiently small (below a fraction of a percent) this "homogeneous" concentration is considerably reduced (or increased, depending on the current direction), which makes the EO strongly non-linear and asymmetric. This analysis provides initial guidance for the design of high-productivity and inexpensive AC electroosmotic pumps.

Fuel cell ion-exchange membrane investigation

NASA Technical Reports Server (NTRS)

Toy, M. S.

1972-01-01

The present deficiencies in the fluorocarbon sulfonic acid membrane used as the solid polymer electrolyte in the H2/O2 fuel cell are studied. Considered are: Adhesives selection, elastomeric formulations, scavenger exploration, and membrane characterization. The significant data are interpreted and recommendations are given for both short and long range further investigations in two of the four major areas: membrane adhesives and membrane stabilization.

High performance of nitrogen and phosphorus removal in an electrolysis-integrated biofilter.

PubMed

Gao, Y; Xie, Y W; Zhang, Q; Yu, Y X; Yang, L Y

A novel electrolysis-integrated biofilter system was developed in this study to evaluate the intensified removal of nitrogen and phosphorus from contaminated water. Two laboratory-scale biofilter systems were established, one with electrolysis (E-BF) and one without electrolysis (BF) as control. The dynamics of intensified nitrogen and phosphorus removal and the changes of inflow and outflow water qualities were also evaluated. The total nitrogen (TN) removal rate was 94.4% in our newly developed E-BF, but only 74.7% in the control BF. Ammonium removal rate was up to 95% in biofilters with or without electrolysis integration with an influent ammonium concentration of 40 mg/L, and the accumulation of nitrate and nitrite was much lower in the effluent of E-BF than that of BF. Thus electrolysis plays an important role in TN removal especially the nitrate and nitrite removal. Phosphorus removal was significantly enhanced, exceeding 90% in E-BF by chemical precipitation, physical adsorption, and flocculation of phosphorus because of the in situ formation of ferric ions by the anodizing of sacrificial iron anodes. Results from this study indicate that the electrolysis integrated biofilter is a promising solution for intensified nitrogen and phosphorus removal.

Electrode kinetics of a water vapor electrolysis cell

NASA Technical Reports Server (NTRS)

Jacobs, G.

1974-01-01

The anodic electrochemical behavior of the water vapor electrolysis cell was investigated. A theoretical review of various aspects of cell overvoltage is presented with special emphasis on concentration overvoltage and activation overvoltage. Other sources of overvoltage are described. The experimental apparatus controlled and measured anode potential and cell current. Potentials between 1.10 and 2.60 V (vs NHE) and currents between 0.1 and 3000 mA were investigated. Different behavior was observed between the standard cell and the free electrolyte cell. The free electrolyte cell followed typical Tafel behavior (i.e. activation overvoltage) with Tafel slopes of about 0.15, and the exchange current densities of 10 to the minus 9th power A/sq cm, both in good agreement with literature values. The standard cell exhibitied this same Tafel behavior at lower current densities but deviated toward lower than expected current densities at higher potentials. This behavior and other results were examined to determine their origin.

A Novel Unitized Regenerative Proton Exchange Membrane Fuel Cell

NASA Technical Reports Server (NTRS)

Murphy, O. J.; Cisar, A. J.; Gonzalez-Martin, A.; Salinas, C. E.; Simpson, S. F.

1996-01-01

A difficulty encountered in designing a unitized regenerative proton exchange membrane (PEM) fuel cell lies in the incompatibility of electrode structures and electrocatalyst materials optimized for either of the two functions (fuel cell or electrolyzer) with the needs of the other function. This difficulty is compounded in previous regenerative fuel cell designs by the fact that water, which is needed for proton conduction in the PEM during both modes of operation, is the reactant supplied to the anode in the electrolyzer mode of operation and the product formed at the cathode in the fuel cell mode. Drawbacks associated with existing regenerative fuel cells have been addressed. In a first innovation, electrodes function either as oxidation electrodes (hydrogen ionization or oxygen evolution) or as reduction electrodes (oxygen reduction or hydrogen evolution) in the fuel cell and electrolyzer modes, respectively. Control of liquid water within the regenerative fuel cell has been brought about by a second innovation. A novel PEM has been developed with internal channels that permit the direct access of water along the length of the membrane. Lateral diffusion of water along the polymer chains of the PEM provides the water needed at electrode/PEM interfaces. Fabrication of the novel single cell unitized regenerative fuel cell and results obtained on testing it are presented.

Anion permselective membrane

NASA Technical Reports Server (NTRS)

Hodgdon, R. B.; Waite, W. A.; Alexander, S. S.

1984-01-01

Two polymer ion exchange membranes were synthesized to fulfill the needs of both electrical resistivity and anolyte/catholyte separation for utility load leveling utilizing the DOE/NASA mixed electrolyte REDOX battery. Both membranes were shown to meet mixed electrolyte utility load leveling criteria. Several modifications of an anion exchange membrane failed to meet utility load leveling REDOX battery criteria using the unmixed electrolyte REDOX cell.

Raman spectroscopy investigation and improved knowledge on industrial cation-exchange membranes involved in electrodialysis process

NASA Astrophysics Data System (ADS)

Chaouki, M.; Huguet, P.; Bribes, J.-L.

1996-06-01

Raman spectra of three specific, industrial, cation-exchange membranes (CEMs) have shown the existence of an extra vibrational band. The relative intensity of this band is different in each membrane spectrum recorded. Chlorosulfonation of polymeric ethylenetrifluoroethylene (ETFE) film grafted with polystyrene chains is used to obtain these CEMs involved in the electrodialysis process. A Raman study of the above reaction has been undertaken and has shown that non-sulfonated polystyrene rings give rise to this extra vibrational band. Different behavior of CEMs synthesized under similar conditions can be explained by a variable amount of non-sulfonated polystyrene rings contained in these materials.

Application of electrolysis to inactivation of antibacterials in clinical use.

PubMed

Nakano, Takashi; Hirose, Jun; Kobayashi, Toyohide; Hiro, Naoki; Kondo, Fumitake; Tamai, Hiroshi; Tanaka, Kazuhiko; Sano, Kouichi

2013-04-01

Contamination of surface water by antibacterial pharmaceuticals (antibacterials) from clinical settings may affect aquatic organisms, plants growth, and environmental floral bacteria. One of the methods to decrease the contamination is inactivation of antibacterials before being discharged to the sewage system. Recently, we reported the novel method based on electrolysis for detoxifying wastewater containing antineoplastics. In the present study, to clarify whether the electrolysis method is applicable to the inactivation of antibacterials, we electrolyzed solutions of 10 groups of individual antibacterials including amikacin sulfate (AMK) and a mixture (MIX) of some commercial antibacterials commonly prescribed at hospitals, and measured their antibacterial activities. AMK was inactivated in its antibacterial activities and its concentration decreased by electrolysis in a time-dependent manner. Eighty to ninety-nine percent of almost all antibacterials and MIX were inactivated within 6h of electrolysis. Additionally, cytotoxicity was not detected in any of the electrolyzed solutions of antibacterials and MIX by the Molt-4-based cytotoxicity test. Copyright © 2012 Elsevier Inc. All rights reserved.

Stability of a Cu0.7Co2.3O4 electrode during the oxygen evolution reaction for alkaline anion-exchange membrane water electrolysis

NASA Astrophysics Data System (ADS)

Kang, Kyoung Eun; Kim, Chi Ho; Lee, Myung Sup; Jung, Chang Wook; Kim, Yang Do; Lee, Jae Ho

2018-01-01

The electrode materials for oxygen evolution, especially non-platinum group metal oxides, have attracted increasing attention. Among the spinel-type transition metal oxides, Cu0.7Co2.3O4 powders were evaluated as a potential replacement for expensive dimensionally stabilized anode materials. Cu0.7Co2.3O4 powder for use as an electrode material for oxygen evolution in an alkaline anion-exchange membrane water electrolyzer was prepared using a thermal decomposition method. The Cu0.7Co2.3O4 powders heat-treated at 250 °C exhibited the same X-ray diffraction patterns without any secondary phases as the Co3O4 spinel structure did. The Cu0.7Co2.3O4 powders heat-treated at 250 °C for 30 minutes showed the smallest mean particle size of approximately 376 nm with the powders having a homogeneous shape and size distribution. The fine powders with a relatively homogeneous size distribution showed a higher current density during the oxygen evolution reaction. The lifetime of the Cu0.7Co2.3O4 electrode was relatively long at a low current density, but was quickly shortened due to physical detachment of the Cu0.7Co2.3O4 powders as the current density was increased. This study showed that the efficiency and the stability of Cu0.7Co2.3O4 powders during the oxygen evolution reaction were related directly to the active electrode area.

Formic acid production using a microbial electrolysis desalination and chemical-production cell.

PubMed

Lu, Yaobin; Luo, Haiping; Yang, Kunpeng; Liu, Guangli; Zhang, Renduo; Li, Xiao; Ye, Bo

2017-11-01

The aim of this study was to investigate the feasibility and optimization of formic acid production in the microbial electrolysis desalination and chemical-production cell (MEDCC). The maximum current density in the MEDCC with 72cm of the anode fiber length (72-MEDCC) reached 24.0±2.0A/m 2 , which was much higher than previously reported. The maximum average formic acid production rate in the 72-MEDCC was 5.28 times higher than that in the MEDCC with 24cm of the anode fiber length (37.00±1.15vs. 7.00±0.25mg/h). High performance in the 72-MEDCC was attributed to small membrane spacing (1mm), high flow rate (1500μL/min) on the membrane surface and high anode biomass. The minimum electricity consumption of 0.34±0.04kWh/kg in the 72-MEDCC was only 3.1-18.8% of those in the EDBMs. The MEDCC should be a promising technology for the formic acid production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Crosslinked anion exchange membranes with primary diamine-based crosslinkers for vanadium redox flow battery application

NASA Astrophysics Data System (ADS)

Cha, Min Suc; Jeong, Hwan Yeop; Shin, Hee Young; Hong, Soo Hyun; Kim, Tae-Ho; Oh, Seong-Geun; Lee, Jang Yong; Hong, Young Taik

2017-09-01

A series of polysulfone-based crosslinked anion exchange membranes (AEMs) with primary diamine-based crosslinkers has been prepared via simple a crosslinking process as low-cost and durable membranes for vanadium redox flow batteries (VRFBs). Chloromethylated polysulfone is used as a precursor polymer for crosslinked AEMs (CAPSU-x) with different degrees of crosslinking. Among the developed AEMs, CAPSU-2.5 shows outstanding dimensional stability and anion (Cl-, SO42-, and OH-) conductivity. Moreover, CAPSU-2.5 exhibits much lower vanadium ion permeability (2.72 × 10-8 cm2 min-1) than Nafion 115 (2.88 × 10-6 cm2 min-1), which results in an excellent coulombic efficiency of 100%. The chemical and operational stabilities of the membranes have been investigated via ex situ soaking tests in 0.1 M VO2+ solution and in situ operation tests for 100 cycles, respectively. The excellent chemical, physical, and electrochemical properties of the CAPSU-2.5 membrane make it suitable for use in VRFBs.

Stereochemistry-Dependent Proton Conduction in Proton Exchange Membrane Fuel Cells.

PubMed

Thimmappa, Ravikumar; Devendrachari, Mruthyunjayachari Chattanahalli; Kottaichamy, Alagar Raja; Tiwari, Omshanker; Gaikwad, Pramod; Paswan, Bhuneshwar; Thotiyl, Musthafa Ottakam

2016-01-12

Graphene oxide (GO) is impermeable to H2 and O2 fuels while permitting H(+) shuttling, making it a potential candidate for proton exchange membrane fuel cells (PEMFC), albeit with a large anisotropy in their proton transport having a dominant in plane (σIP) contribution over the through plane (σTP). If GO-based membranes are ever to succeed in PEMFC, it inevitably should have a dominant through-plane proton shuttling capability (σTP), as it is the direction in which proton gets transported in a real fuel-cell configuration. Here we show that anisotropy in proton conduction in GO-based fuel cell membranes can be brought down by selectively tuning the geometric arrangement of functional groups around the dopant molecules. The results show that cis isomer causes a selective amplification of through-plane proton transport, σTP, pointing to a very strong geometry angle in ionic conduction. Intercalation of cis isomer causes significant expansion of GO (001) planes involved in σTP transport due to their mutual H-bonding interaction and efficient bridging of individual GO planes, bringing down the activation energy required for σTP, suggesting the dominance of a Grotthuss-type mechanism. This isomer-governed amplification of through-plane proton shuttling resulted in the overall boosting of fuel-cell performance, and it underlines that geometrical factors should be given prime consideration while selecting dopant molecules for bringing down the anisotropy in proton conduction and enhancing the fuel-cell performance in GO-based PEMFC.

Post-irradiation time effects on the graft of poly(ethylene-alt-tetrafluoroethylene) (ETFE) films for ion exchange membrane application

NASA Astrophysics Data System (ADS)

Geraldes, Adriana N.; Zen, Heloísa A.; Ribeiro, Geise; Ferreira, Henrique P.; Souza, Camila P.; Parra, Duclerc F.; Santiago, Elisabete I.; Lugão, Ademar B.

2010-03-01

Grafting of styrene followed by sulfonation onto poly(ethylene-alt-tetrafluoroethylene) (ETFE) was studied for synthesis of ion exchange membranes. Radiation-induced grafting of styrene onto ETFE films was investigated after simultaneous irradiation (in post-irradiation condition) using a 60Co source. The ETFE films were irradiated at 20 kGy dose at room temperature and chemical changes were monitored after contact with styrene for grafting. The post-irradiation time was established at 14 days when the films were remained in styrene/toluene 1:1 v/v. After this period the grafting degree was evaluated in the samples. The grafted films were sulfonated using chlorosulfonic acid and 1, 2-dichloroethane 20:80 (v/v) at room temperature for 5 h. The membranes were analyzed by infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), thermogravimetric measurements (TG) and degree of grafting (DOG). The ion exchange capacity (IEC) of membranes was determined by acid-base titration and the values for ETFE membranes were achieved higher than Nafion ® films. Preliminary single cell performance was made using pure H 2 and O 2 as reactants at a cell temperature of 80 °C and atmospheric gas pressure. The fuel cell performance of ETFE films was satisfactory when compared to state-of-art Nafion ® membranes.

Conditioning of sewage sludge with electrolysis: effectiveness and optimizing study to improve dewaterability.

PubMed

Yuan, Haiping; Zhu, Nanwen; Song, Lijie

2010-06-01

The potential benefits of electrolysis-conditioned sludge dewatering treatment were investigated in this paper. Focuses were placed on effectiveness and factors affecting such novel application of electrolysis process. Experiments have demonstrated that a significant improvement of sludge dewaterability evaluated by capillary suction time (CST) could be obtained at a relative low value of electrolysis voltage. A Box-Behnken experimental design based on the response surface methodology (RSM) was applied to evaluate the optimum of the influencing variables. The optimal values for electrolysis voltage, electrode distance and electrolysis time are 21 V, 5 cm and 12 min, respectively, at which the CST reduction efficiency of 18.8+/-3.1% could be achieved, this agreed with that predicted by an established polynomial model in this study. (c) 2010 Elsevier Ltd. All rights reserved.

A proton-exchange membrane prepared by the radiation grafting of styrene and silica into polytetrafluoroethylene films

NASA Astrophysics Data System (ADS)

Yu, Hongyan; Shi, Jianheng; Zeng, Xinmiao; Bao, Mao; Zhao, Xinqing

2009-07-01

A polytetrafluoroethylene (PTFE) based organic-inorganic hybrid proton-exchange membrane was prepared from simultaneous radiation grafting of styrene (St) into porous PTFE membrane with the in situ sol-gel reaction of tetraethoxysilane (TEOS) followed by sulfonation in fuming sulfonic acid. The effect of radiation on the sol-gel reaction was studied. The results show that radiation promotes the sol-gel reaction with the help of St at room temperature. Incorporated silica gel helps to produce higher degree of grafting (DOG). SEM analysis was conducted to confirm that the inorganic silicon oxide was introduced to produce hybrid membrane in this work. The proton conductivity of membrane evaluated using electrochemical impedance spectroscopy is much higher (14.3×10 -2 S cm -1) than that of Nafion ® 117 at temperature of 80 °C with acceptable water uptake 51 wt%.

Endurance Test and Evaluation of Alkaline Water Electrolysis Cells

NASA Technical Reports Server (NTRS)

Kovach, Andrew J.; Schubert, Franz H.; Chang, B. J.; Larkins, Jim T.

1985-01-01

The overall objective of this program is to assess the state of alkaline water electrolysis cell technology and its potential as part of a Regenerative Fuel Cell System (RFCS) of a multikilowatt orbiting powerplant. The program evaluates the endurance capabilities of alkaline electrolyte water electrolysis cells under various operating conditions, including constant condition testing, cyclic testing and high pressure testing. The RFCS demanded the scale-up of existing cell hardware from 0.1 sq ft active electrode area to 1.0 sq ft active electrode area. A single water electrolysis cell and two six-cell modules of 1.0 sq ft active electrode area were designed and fabricated. The two six-cell 1.0 sq ft modules incorporate 1.0 sq ft utilized cores, which allow for minimization of module assembly complexity and increased tolerance to pressure differential. A water electrolysis subsystem was designed and fabricated to allow testing of the six-cell modules. After completing checkout, shakedown, design verification and parametric testing, a module was incorporated into the Regenerative Fuel Cell System Breadboard (RFCSB) for testing at Life Systems, Inc., and at NASA JSC.

Mediated water electrolysis in biphasic systems.

PubMed

Scanlon, Micheál D; Peljo, Pekka; Rivier, Lucie; Vrubel, Heron; Girault, Hubert H

2017-08-30

The concept of efficient electrolysis by linking photoelectrochemical biphasic H 2 evolution and water oxidation processes in the cathodic and anodic compartments of an H-cell, respectively, is introduced. Overpotentials at the cathode and anode are minimised by incorporating light-driven elements into both biphasic reactions. The concepts viability is demonstrated by electrochemical H 2 production from water splitting utilising a polarised water-organic interface in the cathodic compartment of a prototype H-cell. At the cathode the reduction of decamethylferrocenium cations ([Cp 2 *Fe (III) ] + ) to neutral decamethylferrocene (Cp 2 *Fe (II) ) in 1,2-dichloroethane (DCE) solvent takes place at the solid electrode/oil interface. This electron transfer process induces the ion transfer of a proton across the immiscible water/oil interface to maintain electroneutrality in the oil phase. The oil-solubilised proton immediately reacts with Cp 2 *Fe (II) to form the corresponding hydride species, [Cp 2 *Fe (IV) (H)] + . Subsequently, [Cp 2 *Fe (IV) (H)] + spontaneously undergoes a chemical reaction in the oil phase to evolve hydrogen gas (H 2 ) and regenerate [Cp 2 *Fe (III) ] + , whereupon this catalytic Electrochemical, Chemical, Chemical (ECC') cycle is repeated. During biphasic electrolysis, the stability and recyclability of the [Cp 2 *Fe (III) ] + /Cp 2 *Fe (II) redox couple were confirmed by chronoamperometric measurements and, furthermore, the steady-state concentration of [Cp 2 *Fe (III) ] + monitored in situ by UV/vis spectroscopy. Post-biphasic electrolysis, the presence of H 2 in the headspace of the cathodic compartment was established by sampling with gas chromatography. The rate of the biphasic hydrogen evolution reaction (HER) was enhanced by redox electrocatalysis in the presence of floating catalytic molybdenum carbide (Mo 2 C) microparticles at the immiscible water/oil interface. The use of a superhydrophobic organic electrolyte salt was critical to

Manipulating Water in High-Performance Hydroxide Exchange Membrane Fuel Cells through Asymmetric Humidification and Wetproofing

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

Kaspar, RB; Letterio, MP; Wittkopf, JA

Hydroxide exchange membrane fuel cells (HEMFCs) are an emerging low-cost alternative to conventional proton exchange membrane fuel cells. In addition to producing water at the anode, HEMFCs consume water at the cathode, leading to distinctive water transport behavior. We report that gas diffusion layer (GDL) wetproofing strictly lowers cell performance, but that the penalty is much higher when the anode side is wetproofed compared to the cathode side. We attribute this penalty primarily to mass transport losses from anode flooding, suggesting that cathode humidification may be more beneficial than anode humidification for this device. GDLs with little or no wetproofingmore » perform best, yielding a competitive peak power density of 737 mW cm(-2). (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, hup://creativecommons.orgilicenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.« less

Effects of Cationic Pendant Groups on Ionic Conductivity for Anion Exchange Membranes: Structure Conductivity Relationships

NASA Astrophysics Data System (ADS)

Kim, Sojeong; Choi, Soo-Hyung; Lee, Won Bo

Anion exchange membranes(AEMs) have been widely studied due to their various applications, especially for Fuel cells. Previous proton exchange membranes(PEMs), such as Nafions® have better conductivity than AEMs so far. However, technical limitations such as slow electrode kinetics, carbon monoxide (CO) poisoning of metal catalysts, high methanol crossover and high cost of Pt-based catalyst detered further usages. AEMs have advantages to supplement its drawbacks. AEMs are environmentally friendly and cost-efficient. Based on the well-defined block copolymer, self-assembled morphology is expected to have some relationship with its ionic conductivity. Recently AEMs based on various cations, including ammonium, phosphonium, guanidinium, imidazolium, metal cation, and benzimidazolium cations have been developed and extensively studied with the aim to prepare high- performance AEMs. But more fundamental approach, such as relationships between nanostructure and conductivity is needed. We use well-defined block copolymer Poly(styrene-block-isoprene) as a backbone which is synthesized by anionic polymerization. Then we graft various cationic functional groups and analysis the relation between morphology and conductivity. Theoretical and computational soft matter lab.

Enhancing the efficiency of zero valent iron by electrolysis: Performance and reaction mechanism.

PubMed

Xiong, Zhaokun; Lai, Bo; Yang, Ping

2018-03-01

Electrolysis was applied to enhance the efficiency of micron-size zero valent iron (mFe 0 ) and thereby promote p-nitrophenol (PNP) removal. The rate of PNP removal by mFe 0 with electrolysis was determined in cylindrical electrolysis reactor that employed annular aluminum plate cathode as a function of experimental factors, including initial pH, mFe 0 dosage and current density. The rate constants of PNP removal by Ele-mFe 0 were 1.72-144.50-fold greater than those by pristine mFe 0 under various tested conditions. The electrolysis-induced improvement could be primarily ascribed to stimulated mFe 0 corrosion, as evidenced by Fe 2+ release. The application of electrolysis could extend the working pH range of mFe 0 from 3.0 to 6.0 to 3.0-10.0 for PNP removal. Additionally, intermediates analysis and scavengers experiments unraveled the reduction capacity of mFe 0 was accelerated in the presence of electrolysis instead of oxidation. Moreover, the electrolysis effect could also delay passivation of mFe 0 under acidic condition, as evidenced by SEM-EDS, XRD, and XPS analysis after long-term operation. This is mainly due to increased electromigration meaning that iron corrosion products (iron hydroxides and oxides) are not primarily formed in the vicinity of the mFe 0 or at its surface. In the presence of electrolysis, the effect of electric field significantly promoted the efficiency of electromigration, thereby enhanced mFe 0 corrosion and eventually accelerated the PNP removal rates. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ultrasonic-assisted synthesis of ZrO2 nanoparticles and their application to improve the chemical stability of Nafion membrane in proton exchange membrane (PEM) fuel cells.

PubMed

Taghizadeh, Mohammad Taghi; Vatanparast, Morteza

2016-12-01

Zirconium dioxide (ZrO2) nanoparticles were fabricated successfully via ultrasonic-assisted method using ZrO(NO3)2·H2O, ethylenediamine and hydrazine as precursors in aqueous solution. Morphology, structure and composition of the obtained products were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR) and diffuse reflectance spectroscopy (DRS). Then, the synthesized nanoparticles were used to prepare Nafion/ZrO2 nanocomposite membranes. The properties of the membranes were studied by ion exchange capacity (IEC) proton conductivity (σ), thermal stability and water uptake measurements. The ex-situ Fenton's test was used to investigate the chemical stability of the membranes. From our results, compared with Nafion membrane, the nanocomposite membrane exhibited lower fluoride release and weight loss. Therefore, it can concluded that Nafion/ZrO2 nanocomposite exhibit more chemical stability than the pure Nafion membrane. ATR-FTIR spectra and SEM surface images of membranes also confirm these results. Copyright © 2016 Elsevier Inc. All rights reserved.

High Temperature Electrolysis 4 kW Experiment Design, Operation, and Results

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

J.E. O'Brien; X. Zhang; K. DeWall

2012-09-01

This report provides results of long-term stack testing completed in the new high-temperature steam electrolysis multi-kW test facility recently developed at INL. The report includes detailed descriptions of the piping layout, steam generation and delivery system, test fixture, heat recuperation system, hot zone, instrumentation, and operating conditions. This facility has provided a demonstration of high-temperature steam electrolysis operation at the 4 kW scale with advanced cell and stack technology. This successful large-scale demonstration of high-temperature steam electrolysis will help to advance the technology toward near-term commercialization.

Preface–JES focus issue on electrolysis for increased renewable energy penetration

DOE PAGES

Pivovar, B.; Carmo, M.; Ayers, K.; ...

2016-10-22

The objective here of this special issue is to help identify the leading research being performed in the electrolysis area and provide context for the electrolysis advances that will be required for a larger role in tomorrow's energy system.

Intensification of heat and mass transfer by ultrasound: application to heat exchangers and membrane separation processes.

PubMed

Gondrexon, N; Cheze, L; Jin, Y; Legay, M; Tissot, Q; Hengl, N; Baup, S; Boldo, P; Pignon, F; Talansier, E

2015-07-01

This paper aims to illustrate the interest of ultrasound technology as an efficient technique for both heat and mass transfer intensification. It is demonstrated that the use of ultrasound results in an increase of heat exchanger performances and in a possible fouling monitoring in heat exchangers. Mass transfer intensification was observed in the case of cross-flow ultrafiltration. It is shown that the enhancement of the membrane separation process strongly depends on the physico-chemical properties of the filtered suspensions. Copyright © 2014 Elsevier B.V. All rights reserved.

Graphene-doped electrospun nanofiber membrane electrodes and proton exchange membrane fuel cell performance

NASA Astrophysics Data System (ADS)

Wei, Meng; Jiang, Min; Liu, Xiaobo; Wang, Min; Mu, Shichun

2016-09-01

A rational electrode structure can allow proton exchange membrane (PEM) fuel cells own high performance with a low noble metal loading and an optimal transport pathway for reaction species. In this study, we develop a graphene doped polyacrylonitile (PAN)/polyvinylident fluoride (PVDF) (GPP) electrospun nanofiber electrode with improved electrical conductivity and high porosity, which could enhance the triple reaction boundary and promote gas and water transport throughout the porous electrode. Thus the increased electrochemical active surface area (ECSA) of Pt catalysts and fuel cell performance can be expected. As results, the ECSA of hot-pressed electrospun electrodes with 2 wt% graphene oxide (GO) is up to 84.3 m2/g, which is greatly larger than that of the conventional electrode (59.5 m2/g). Significantly, the GPP nanofiber electrospun electrode with Pt loading of 0.2 mg/cm2 exhibits higher fuel cell voltage output and stability than the conventional electrode.

A review of high temperature co-electrolysis of H2O and CO2 to produce sustainable fuels using solid oxide electrolysis cells (SOECs): advanced materials and technology.

PubMed

Zheng, Yun; Wang, Jianchen; Yu, Bo; Zhang, Wenqiang; Chen, Jing; Qiao, Jinli; Zhang, Jiujun

2017-03-06

High-temperature solid oxide electrolysis cells (SOECs) are advanced electrochemical energy storage and conversion devices with high conversion/energy efficiencies. They offer attractive high-temperature co-electrolysis routes that reduce extra CO 2 emissions, enable large-scale energy storage/conversion and facilitate the integration of renewable energies into the electric grid. Exciting new research has focused on CO 2 electrochemical activation/conversion through a co-electrolysis process based on the assumption that difficult C[double bond, length as m-dash]O double bonds can be activated effectively through this electrochemical method. Based on existing investigations, this paper puts forth a comprehensive overview of recent and past developments in co-electrolysis with SOECs for CO 2 conversion and utilization. Here, we discuss in detail the approaches of CO 2 conversion, the developmental history, the basic principles, the economic feasibility of CO 2 /H 2 O co-electrolysis, and the diverse range of fuel electrodes as well as oxygen electrode materials. SOEC performance measurements, characterization and simulations are classified and presented in this paper. SOEC cell and stack designs, fabrications and scale-ups are also summarized and described. In particular, insights into CO 2 electrochemical conversions, solid oxide cell material behaviors and degradation mechanisms are highlighted to obtain a better understanding of the high temperature electrolysis process in SOECs. Proposed research directions are also outlined to provide guidelines for future research.

A concise guide to sustainable PEMFCs: recent advances in improving both oxygen reduction catalysts and proton exchange membranes.

PubMed

Scofield, Megan E; Liu, Haiqing; Wong, Stanislaus S

2015-08-21

The rising interest in fuel cell vehicle technology (FCV) has engendered a growing need and realization to develop rational chemical strategies to create highly efficient, durable, and cost-effective fuel cells. Specifically, technical limitations associated with the major constituent components of the basic proton exchange membrane fuel cell (PEMFC), namely the cathode catalyst and the proton exchange membrane (PEM), have proven to be particularly demanding to overcome. Therefore, research trends within the community in recent years have focused on (i) accelerating the sluggish kinetics of the catalyst at the cathode and (ii) minimizing overall Pt content, while simultaneously (a) maximizing activity and durability as well as (b) increasing membrane proton conductivity without causing any concomitant loss in either stability or as a result of damage due to flooding. In this light, as an example, high temperature PEMFCs offer a promising avenue to improve the overall efficiency and marketability of fuel cell technology. In this Critical Review, recent advances in optimizing both cathode materials and PEMs as well as the future and peculiar challenges associated with each of these systems will be discussed.

The critical relation between chemical stability of cations and water in anion exchange membrane fuel cells environment

NASA Astrophysics Data System (ADS)

Dekel, Dario R.; Willdorf, Sapir; Ash, Uri; Amar, Michal; Pusara, Srdjan; Dhara, Shubhendu; Srebnik, Simcha; Diesendruck, Charles E.

2018-01-01

Anion exchange membrane fuel cells can potentially revolutionize energy storage and delivery; however, their commercial development is hampered by a significant technological impedance: the chemical decomposition of the anion exchange membranes during operation. The hydroxide anions, while transported from the cathode to the anode, attack the positively charged functional groups in the polymer membrane, neutralizing it and suppressing its anion-conducting capability. In recent years, several new quaternary ammonium salts have been proposed to address this challenge, but while they perform well in ex-situ chemical studies, their performance is very limited in real fuel cell studies. Here, we use experimental work, corroborated by molecular dynamics modeling to show that water concentration in the environment of the hydroxide anion, as well as temperature, significantly impact its reactivity. We compare different quaternary ammonium salts that have been previously studied and test their stabilities in the presence of relatively low hydroxide concentration in the presence of different amounts of solvating water molecules, as well as different temperatures. Remarkably, with the right amount of water and at low enough temperatures, even quaternary ammonium salts which are considered "unstable", present significantly improved lifetime.

Electrolysis of lunar soil to produce oxygen and metals

NASA Technical Reports Server (NTRS)

Colson, Russell O.; Haskin, Larry A.; Keller, R.

1991-01-01

The discussion of melt electrolysis consists of three sections. The implications of the chemistry and physics of fluxed and raw melts on melt electrolysis are discussed first. This includes discussion of the factor that influence melt resistivity, melt viscosity, oxygen production efficiency, and the theoretical energy required to produce oxygen. Second, the implications of phase equilibria and solubilities in silicate melts on the selection of materials for container and electrodes are discussed. The implications of proposed container and electrode materials on melt composition and how this effects expected resistivities, viscosities, as outlined in the first section are discussed. Finally, a general discussion of the basic features of both the fluxed and unfluxed melt electrolysis is given, including their advantages and disadvantages and how they compare with alternative processes.

Bionic multisilicon copolymers used as novel cross-linking agents for preparing anion exchange hybrid membranes.

PubMed

Wu, Yonghui; Luo, Jingyi; Wu, Cuiming; Xu, Tongwen; Fu, Yanxun

2011-05-26

Bionic multisilicon copolymers have long-main chains and many branched chains, and contain multifunctional groups of -N(+)(CH(3))(3)Cl(-) and -Si(OCH(3))(3), which are similar to the stem, branch, fruit, and acetabula of a vine from bionic aspect, respectively. They have high flexibility, charge density, and cross-linking ability and thus can be used as novel cross-linking agents for preparing anion-exchange hybrid membranes. High content of -Si(OCH(3))(3) groups (68-78%) is suitable to enhance membrane stabilities. The membranes are stable in 65 °C water up to 120 h and can keep integrity in 2 mol/L NaOH for 192 h. High content of -N(+)(CH(3))(3)Cl(-) groups (42-55%) is suitable to enhance membrane electrical properties. The membranes have low membrane resistance (R(m), 0.59-0.94 Ω cm(2)) and high diffusion dialysis performance. The acid (H(+)) dialysis coefficients (U(H)) are in the range of 0.007-0.075 m h(-1) at room temperature and 0.015-0.115 m h(-1) at 40 °C. The separation factor (S(H/Fe)) can reach up to 43 at room temerature and 49 at 40 °C. All of the membranes are highly homogeneous, mechanically stable (21-31 MPa, 25-147%), and thermally stable (227-275 °C for halide form membranes, and 157-172 °C for OH(-) form membranes). Hence, the investigation of multisilicon copolymers will give rise to a new developing field in material and membrane sciences.

Multiple-membrane multiple-electrolyte redox flow battery design

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

Yan, Yushan; Gu, Shuang; Gong, Ke

A redox flow battery is provided. The redox flow battery involves multiple-membrane (at least one cation exchange membrane and at least one anion exchange membrane), multiple-electrolyte (one electrolyte in contact with the negative electrode, one electrolyte in contact with the positive electrode, and at least one electrolyte disposed between the two membranes) as the basic characteristic, such as a double-membrane, triple electrolyte (DMTE) configuration or a triple-membrane, quadruple electrolyte (TMQE) configuration. The cation exchange membrane is used to separate the negative or positive electrolyte and the middle electrolyte, and the anion exchange membrane is used to separate the middle electrolytemore » and the positive or negative electrolyte.« less

Highly stable pyridinium-functionalized cross-linked anion exchange membranes for all vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Zeng, L.; Zhao, T. S.; Wei, L.; Zeng, Y. K.; Zhang, Z. H.

2016-11-01

It has recently been demonstrated that the use of anion exchange membranes (AEMs) in vanadium redox flow batteries (VRFBs) can reduce the migration of vanadium ions through the membrane due to the Donnan exclusion effect among the positively charged functional groups and vanadium ions. However, AEMs are plagued by low chemical stability in harsh chemical environments. Here we propose and fabricate a pyridinium-functionalized cross-linked AEM for VRFBs. The pyridinium-functionalized bromomethylated poly (2,6-dimethyl-1,4-phenylene oxide) exhibits a superior chemical stability as a result of the strengthened internal cross-linking networks and the chemical inertness of the polymer backbone. Therefore, the membrane exhibits littler decay in a harsh environment for 20 days during the course of an ex situ immersion test. A cycling test also demonstrates that the VRFB assembled with the membrane enable to retain 80% of the initial discharge capacity over 537 cycles with a capacity decay rate of 0.037% cycle-1. Meanwhile, the membrane also shows a low vanadium permeability and a reasonably high conductivity in supporting electrolytes. Hence, all the measurements and performance tests reported in this work suggest that the membrane is a promising AEM for redox flow batteries to achieve excellent cycling stability and superior cell performance.

Advancements in oxygen generation and humidity control by water vapor electrolysis

NASA Technical Reports Server (NTRS)

Heppner, D. B.; Sudar, M.; Lee, M. C.

1988-01-01

Regenerative processes for the revitalization of manned spacecraft atmospheres or other manned habitats are essential for realization of long-term space missions. These processes include oxygen generation through water electrolysis. One promising technique of water electrolysis is the direct conversion of the water vapor contained in the cabin air to oxygen. This technique is the subject of the present program on water vapor electrolysis development. The objectives were to incorporate technology improvements developed under other similar electrochemical programs and add new ones; design and fabricate a mutli-cell electrochemical module and a testing facility; and demonstrate through testing the improvements. Each aspect of the water vapor electrolysis cell was reviewed. The materials of construction and sizing of each element were investigated analytically and sometime experimentally. In addition, operational considerations such as temperature control in response to inlet conditions were investigated. Three specific quantitative goals were established.

Experimental study of the electrolysis of silicate melts

NASA Technical Reports Server (NTRS)

Keller, Rudolf

1992-01-01

Melting and electrolyzing lunar silicates yields oxygen gas and potentially can be practiced in situ to produce oxygen. With the present experiments conducted with simulant oxides at 1425-1480 C, it was ascertained that oxygen can be obtained anodically at feasible rates and current efficiencies. An electrolysis cell was operated with platinum anodes in a sealed vessel, and the production of gas was monitored. In these electrolysis experiments, stability of anodes remained a problem, and iron and silicon did not reduce readily into the liquid silver cathode.

A Small-Scale and Low-Cost Apparatus for the Electrolysis of Water

ERIC Educational Resources Information Center

Eggeen, Per-Odd; Kvittingen, Lise

2004-01-01

The construction of two simple, inexpensive apparatuses that clearly show the electrolysis of water are described. Traditionally the electrolysis of water is conducted in a Hofmann apparatus which is expensive and fragile.

A novel unitized regenerative proton exchange membrane fuel cell

NASA Technical Reports Server (NTRS)

Murphy, O. J.; Cisar, A. J.; Gonzalez-Martin, A.; Salinas, C. E.; Simpson, S. F.

1995-01-01

A difficulty encountered in designing a unitized regenerative proton exchange membrane (PEM) fuel cell lies in the incompatibility of electrode structures and electrocatalyst materials optimized for either of the two functions (fuel cell or electrolyzer) with the needs of the other function. This difficulty is compounded in previous regenerative fuel cell designs by the fact that water, which is needed for proton conduction in the PEM during both modes of operation, is the reactant supplied to the anode in the electrolyzer mode of operation and the product formed at the cathode in the fuel cell mode. Drawbacks associated with existing regenerative fuel cells have been addressed in work performed at Lynntech. In a first innovation, electrodes function either as oxidation electrodes (hydrogen ionization or oxygen evolution) or as reduction electrodes (oxygen reduction or hydrogen evolution) in the fuel cell and electrolyzer modes, respectively. Control of liquid water within the regenerative fuel cell has been brought about by a second innovation. A novel PEM has been developed with internal channels that permit the direct access of water along the length of the membrane. Lateral diffusion of water along the polymer chains of the PEM provides the water needed at electrode/PEM interfaces. Fabrication of the novel unitized regenerative fuel cell and results obtained on testing it will be presented.

Enhanced Flux and Electrochemical Cleaning of Silicate Scaling on Carbon Nanotube-Coated Membrane Distillation Membranes Treating Geothermal Brines.

PubMed

Tang, Li; Iddya, Arpita; Zhu, Xiaobo; Dudchenko, Alexander V; Duan, Wenyan; Turchi, Craig; Vanneste, Johann; Cath, Tzahi Y; Jassby, David

2017-11-08

The desalination of inland brackish groundwater offers the opportunity to provide potable drinking water to residents and industrial cooling water to industries located in arid regions. Geothermal brines are used to generate electricity, but often contain high concentrations of dissolved salt. Here, we demonstrate how the residual heat left in spent geothermal brines can be used to drive a membrane distillation (MD) process and recover desalinated water. Porous polypropylene membranes were coated with a carbon nanotube (CNT)/poly(vinyl alcohol) layer, resulting in composite membranes having a binary structure that combines the hydrophobic properties critical for MD with the hydrophilic and conductive properties of the CNTs. We demonstrate that the addition of the CNT layer increases membrane flux due to enhanced heat transport from the bulk feed to the membrane surface, a result of CNT's high thermal transport properties. Furthermore, we show how hydroxide ion generation, driven by water electrolysis on the electrically conducting membrane surface, can be used to efficiently dissolve silicate scaling that developed during the process of desalinating the geothermal brine, negating the need for chemical cleaning.

Development of high-productivity, strong cation-exchange adsorbers for protein capture by graft polymerization from membranes with different pore sizes

PubMed Central

Chenette, Heather C.S.; Robinson, Julie R.; Hobley, Eboni; Husson, Scott M.

2012-01-01

This paper describes the surface modification of macroporous membranes using ATRP (atom transfer radical polymerization) to create cation-exchange adsorbers with high protein binding capacity at high product throughput. The work is motivated by the need for a more economical and rapid capture step in downstream processing of protein therapeutics. Membranes with three reported nominal pore sizes (0.2, 0.45, 1.0 μm) were modified with poly(3-sulfopropyl methacrylate, potassium salt) tentacles, to create a high density of protein binding sites. A special formulation was used in which the monomer was protected by a crown ether to enable surface-initiated ATRP of this cationic polyelectrolyte. Success with modification was supported by chemical analysis using Fourier-transform infrared spectroscopy and indirectly by measurement of pure water flux as a function of polymerization time. Uniformity of modification within the membranes was visualized with confocal laser scanning microscopy. Static and dynamic binding capacities were measured using lysozyme protein to allow comparisons with reported performance data for commercial cation-exchange materials. Dynamic binding capacities were measured for flow rates ranging from 13 to 109 column volumes (CV)/min. Results show that this unique ATRP formulation can be used to fabricate cation-exchange membrane adsorbers with dynamic binding capacities as high as 70 mg/mL at a throughput of 100 CV/min and unprecedented productivity of 300 mg/mL/min. PMID:23175597

Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane

PubMed Central

Monet, Michael; Birgy-Barelli, Eléonore; Léna, Isabelle; Counillon, Laurent

2015-01-01

Endosomal acidification is critical for a wide range of processes, such as protein recycling and degradation, receptor desensitization, and neurotransmitter loading in synaptic vesicles. This acidification is described to be mediated by proton ATPases, coupled to ClC chloride transporters. Highly-conserved electroneutral protons transporters, the Na+/H+ exchangers (NHE) 6, 7 and 9 are also expressed in these compartments. Mutations in their genes have been linked with human cognitive and neurodegenerative diseases. Paradoxically, their roles remain elusive, as their intracellular localization has prevented detailed functional characterization. This manuscript shows a method to solve this problem. This consists of the selection of mutant cell lines, capable of surviving acute cytosolic acidification by retaining intracellular NHEs at the plasma membrane. It then depicts two complementary protocols to measure the ion selectivity and activity of these exchangers: (i) one based on intracellular pH measurements using fluorescence video microscopy, and (ii) one based on the fast kinetics of lithium uptake. Such protocols can be extrapolated to measure other non-electrogenic transporters. Furthermore, the selection procedure presented here generates cells with an intracellular retention defective phenotype. Therefore these cells will also express other vesicular membrane proteins at the plasma membrane. The experimental strategy depicted here may therefore constitute a potentially powerful tool to study other intracellular proteins that will be then expressed at the plasma membrane together with the vesicular Na+/H+ exchangers used for the selection. PMID:25867523

Functional characterization of Na+/H+ exchangers of intracellular compartments using proton-killing selection to express them at the plasma membrane.

PubMed

Milosavljevic, Nina; Poët, Mallorie; Monet, Michael; Birgy-Barelli, Eléonore; Léna, Isabelle; Counillon, Laurent

2015-03-30

Endosomal acidification is critical for a wide range of processes, such as protein recycling and degradation, receptor desensitization, and neurotransmitter loading in synaptic vesicles. This acidification is described to be mediated by proton ATPases, coupled to ClC chloride transporters. Highly-conserved electroneutral protons transporters, the Na+/H+ exchangers (NHE) 6, 7 and 9 are also expressed in these compartments. Mutations in their genes have been linked with human cognitive and neurodegenerative diseases. Paradoxically, their roles remain elusive, as their intracellular localization has prevented detailed functional characterization. This manuscript shows a method to solve this problem. This consists of the selection of mutant cell lines, capable of surviving acute cytosolic acidification by retaining intracellular NHEs at the plasma membrane. It then depicts two complementary protocols to measure the ion selectivity and activity of these exchangers: (i) one based on intracellular pH measurements using fluorescence video microscopy, and (ii) one based on the fast kinetics of lithium uptake. Such protocols can be extrapolated to measure other non-electrogenic transporters. Furthermore, the selection procedure presented here generates cells with an intracellular retention defective phenotype. Therefore these cells will also express other vesicular membrane proteins at the plasma membrane. The experimental strategy depicted here may therefore constitute a potentially powerful tool to study other intracellular proteins that will be then expressed at the plasma membrane together with the vesicular Na+/H+ exchangers used for the selection.

Pyruvate and ketone-body transport across the mitochondrial membrane. Exchange properties, pH-dependence and mechanism of the carrier.

PubMed

Halestrap, A P

1978-06-15

The effects of exchangeable ions and pH on the efflux of pyruvate from preloaded mitochondria are reported. Efflux obeys first-order kinetics, and the stimulation of efflux by exchangeable ions such as acetoacetate and lactate obeys Michaelis--Menten kinetics. The apparent Km value +/- S.E. for acetoacetate was 0.56 +/- 0.14 mM (n = 5) and that for lactate 12.3 +/- 2.3 mM (n = 6). The Vmax. values +/- S.E. at 0 degrees C were 16.2 +/- 2.0 and 21.9 +/- 2.7 nmol/min per mg of protein. The exchange of a variety of other substituted monocarboxylates was also studied. Efflux was also stimulated by increasing the external pH. The data gave a pK for the transport process of 8.35 and a Vmax. of 3.31 +/- 0.14 nmol/min per mg. The similarity of the Vmax. values for various exchangeable ions but the difference of this from the Vmax. in the absence of exchangeable ions may indicate that transport of pyruvate occurs with H+ and not in exchange for an OH- ion. The inhibition of transport by alpha-cyano-4-hydroxycinnamate took several seconds to reach completion at 0 degrees C. It is proposed that inhibition occurs by binding to the substrate site and subsequent reaction with an -SH group on the inside of the membrane. The inhibitor can be displaced by substrates that can also enter the mitochondria independently of the carrier and so compete with the inhibitor for the substrate-binding site on the inside of the membrane. A mechanism for transport is proposed that invokes a transition state of pyruvate involving addition of an -SH group to the 2-carbon of pyruvate. Evidence is presented that suggests that ketone bodies may cross the mitochondrial membrane either on the carrier or by free diffusion. The physiological involvement of the carrier in ketone-body metabolism is discussed. The role of ketone bodies and pH in the physiological regulation of pyruvate transport is considered.

Analysis of cavitation effect for water purifier using electrolysis

NASA Astrophysics Data System (ADS)

Shin, Dong Ho; Ko, Han Seo; Lee, Seung Ho

2015-11-01

Water is a limited and vital resource, so it should not be wasted by pollution. A development of new water purification technology is urgent nowadays since the original and biological treatments are not sufficient. The microbubble-aided method was investigated for removal of algal in this study since it overcomes demerits of the existing purification technologies. Thus, the cavitation effect in a venturi-type tube using the electrolysis was analyzed. Ruthenium-coated titanium plates were used as electrodes. Optimum electrode interval and applied power were determined for the electrolysis. Then, the optimized electrodes were installed in the venturi-type tube for generating cavitation. The cavitation effect could be enhanced without any byproduct by the bubbly flow induced by the electrolysis. The optimum mass flow rate and current were determined for the cavitation with the electrolysis. Finally, the visualization techniques were used to count the cell number of algal and microbubbles for the confirmation of the performance. As a result, the energy saving and high efficient water purifier was fabricated in this study. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Korean government (MEST) (No. 2013R1A2A2A01068653).

A green approach for preparing anion exchange membrane based on cardo polyetherketone powders

NASA Astrophysics Data System (ADS)

Hu, Jue; Zhang, Chengxu; Zhang, Xiaodong; Chen, Longwei; Jiang, Lin; Meng, Yuedong; Wang, Xiangke

2014-12-01

Anion exchange membranes (AEMs) have attracted great attention due to their irreplaceable role in platinum-free fuel cell applications. The majority of AEM preparations have been performed in two steps: the grafting of functional groups and quaternization. Here, we adopted a simpler, more eco-friendly approach for the first time to prepare AEMs by atmospheric-pressure plasma-grafting. This approach enables the direct introduction of anion exchange groups (benzyltrimethylammonium groups) into the polymer matrix, overcoming the need for toxic chloromethyl ether and quaternization reagents. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and 1H NMR spectroscopy results demonstrate that benzyltrimethylammonium groups have been successfully grafted into the cardo polyetherketone (PEK-C) matrix. Thermogravimetric analysis reveals that the plasma-grafting technique is a facile and non-destructive method able to improve the thermal stability of the polymer matrix due to the strong preservation of the PEK-C backbone structure and the cross-linking of the grafted side chains. The plasma-grafted PG-NOH membrane, which shows satisfactory alcohol resistance (ethanol permeability of 6.3 × 10-7 cm2 s-1), selectivity (1.2 × 104 S s cm-3), thermal stability (safely used below 130 °C), chemical stability, anion conductivity (7.7 mS cm-1 at 20 °C in deionized water) and mechanical properties is promising for the construction of high-performance fuel cells.

Proton exchange membrane based on chitosan and solvent-free carbon nanotube fluids for fuel cells applications.

PubMed

Wang, Jie; Gong, Chunli; Wen, Sheng; Liu, Hai; Qin, Caiqin; Xiong, Chuanxi; Dong, Lijie

2018-04-15

Poor dispersion and inert ionic conduction are two major obstacles towards using carbon nanotubes (CNTs) to modify polymer electrolyte membranes (PEMs) in energy conversion devices. In this work, solvent-free carbon nanotube fluids (CNT fluids) with liquid-like behavior are prepared through an ion exchange method and incorporated into a chitosan (CS) matrix to fabricate composite membranes. The electrostatic interactions between SO 3 - groups in the CNT fluids and NH 2 groups in the CS matrix, in addition to the unique flow properties of the CNT fluids, promote the uniform dispersion of CNT fluids in the CS matrix. Markedly, the CS/CNT fluid-3 composite membrane is simultaneously reinforced and toughened by 180% and 300% compared to pure CS membrane, respectively. Moreover, the SO 3 - groups in the CNT fluids facilitate the proton transfer such that the proton conductivity of CS/CNT fluid-3 composite membrane reaches a maximum value of 0.044 S cm -1 at 80 °C. Copyright © 2018 Elsevier Ltd. All rights reserved.

Photosynthetic solar cell using nanostructured proton exchange membrane for microbial biofilm prevention.

PubMed

Lee, Dong Hyun; Oh, Hwa Jin; Bai, Seoung Jae; Song, Young Seok

2014-06-24

Unwanted biofilm formation has a detrimental effect on bioelectrical energy harvesting in microbial cells. This issue still needs to be solved for higher power and longer durability and could be resolved with the help of nanoengineering in designing and manufacturing. Here, we demonstrate a photosynthetic solar cell (PSC) that contains a nanostructure to prevent the formation of biofilm by micro-organisms. Nanostructures were fabricated using nanoimprint lithography, where a film heater array system was introduced to precisely control the local wall temperature. To understand the heat and mass transfer phenomena behind the manufacturing and energy harvesting processes of PSC, we carried out a numerical simulation and experimental measurements. It revealed that the nanostructures developed on the proton exchange membrane enable PSC to produce enhanced output power due to the retarded microbial attachment on the Nafion membrane. We anticipate that this strategy can provide a pathway where PSC can ensure more renewable, sustainable, and efficient energy harvesting performance.

Hydrogen Production from Nuclear Energy via High Temperature Electrolysis

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

James E. O'Brien; Carl M. Stoots; J. Stephen Herring

2006-04-01

This paper presents the technical case for high-temperature nuclear hydrogen production. A general thermodynamic analysis of hydrogen production based on high-temperature thermal water splitting processes is presented. Specific details of hydrogen production based on high-temperature electrolysis are also provided, including results of recent experiments performed at the Idaho National Laboratory. Based on these results, high-temperature electrolysis appears to be a promising technology for efficient large-scale hydrogen production.

Effects of Polymer Structure and Relaxations on Ionic Conductivity in Anion Exchange Membranes with Quaternary Ammonium Functional Groups

NASA Astrophysics Data System (ADS)

Maes, Ashley M.

Anion exchange membranes (AEMs) are of considerable interest to developers and researchers of electrochemical conversion and storage devices such as anion exchange membrane fuel cells (AAEMFCs), alkaline polymer electrolyte electrolysers, redox flow batteries and bioelectrochemical devices. AEMs are generally in competition with more established proton exchange membranes (PEMs), but offer the potential for reduction of materials costs and greater fuel flexibility across these applications. This work includes an introduction to AEMs in the context of fuel cell technologies and some key techniques for AEM characterization. There are many synthetic strategies to incorporate cationic functional groups, which promote anion transport, into a polymer matrix. Two membrane chemistries are investigated in the following chapters. The first is based on a simple synthesis procedure that produced a membrane consisting of random, crosslinked polypropylene- ran-polyethyleneimine with quaternary ammonium functional groups. This membrane had moderate chloride ionic conductivity of 0.03 S cm -1 at 95 °C and high water uptake with minimal dimensional swelling. However, the lack of control of crosslink location and density during synthesis produced a material with a very random nature, making it a poor candidate for more fundamental transport studies. The second membrane chemistry is a block copolymer with a hydrophobic and hydrophilic block. The hydrophobic block was selected to provide favorable mechanical and barrier characteristics while a hydrophilic block was selected to provide water uptake and anion conducting functionalities. Poly(vinyl benzyl trimethyl ammonium bromide)-b-poly(methylbutylene) ([PVBTMA][Br]- b-PMB) was synthesized by partners at the University of Massachusetts-Amherst with varied degrees of functionalization (DF) along the hydrophilic block, resulting in ion exchange capacities ranging from 0.77 to 2.20 mmol g -1. Water uptake, in-plane ionic conductivity and

Carbon dioxide and water vapor high temperature electrolysis

NASA Technical Reports Server (NTRS)

Isenberg, Arnold O.; Verostko, Charles E.

1989-01-01

The design, fabrication, breadboard testing, and the data base obtained for solid oxide electrolysis systems that have applications for planetary manned missions and habitats are reviewed. The breadboard tested contains sixteen tubular cells in a closely packed bundle for the electrolysis of carbon dioxide and water vapor. The discussion covers energy requirements, volume, weight, and operational characteristics related to the measurement of the reactant and product gas compositions, temperature distribution along the electrolyzer tubular cells and through the bundle, and thermal energy losses. The reliability of individual cell performance in the bundle configuration is assessed.

Selective growth of MoS2 for proton exchange membranes with extremely high selectivity.

PubMed

Feng, Kai; Tang, Beibei; Wu, Peiyi

2013-12-26

Proton conductivity and methanol permeability are the most important transport properties of proton exchange membranes (PEMs). The ratio of proton conductivity to methanol permeability is usually called selectivity. Herein, a novel strategy of in situ growth of MoS2 is employed to prepare MoS2/Nafion composite membranes for highly selective PEM. The strong interactions between the Mo precursor ((NH4)2MoS4) and Nafion's sulfonic groups in a suitable solvent environment (DMF) probably lead to a selective growth of MoS2 flakes mainly around the ionic clusters of the resultant MoS2/Nafion composite membrane. Therefore, it would significantly promote the aggregation and hence lead to a better connectivity of these ionic clusters, which favors the increase in proton conductivity. Meanwhile, the existence of MoS2 in the ionic channels effectively prevents methanol transporting through the PEM, contributing to the dramatic decrease in the methanol permeability. Consequently, the MoS2/Nafion composite membranes exhibit greatly increased selectivity. Under some severe conditions, such as 50 °C with 80 v/v% of methanol concentration, an increase in the membrane selectivity by nearly 2 orders of magnitude compared with that of the recast Nafion membrane could be achieved here, proving our method as a very promising way to prepare high-performance PEMs. All these conclusions are confirmed by various characterizations, such as (FE-) SEM, TEM, AFM, IR, Raman, TGA, XRD, etc.

Alkaline direct alcohol fuel cells using an anion exchange membrane

NASA Astrophysics Data System (ADS)

Matsuoka, Koji; Iriyama, Yasutoshi; Abe, Takeshi; Matsuoka, Masao; Ogumi, Zempachi

Alkaline direct alcohol fuel cells using an OH-form anion exchange membrane and polyhydric alcohols were studied. A high open circuit voltage of ca. 800 mV was obtained for a cell using Pt-Ru/C (anode) and Pt/C (cathode) at 323 K, which was about 100-200 mV higher than that for a DMFC using Nafion ®. The maximum power densities were in the order of ethylene glycol > glycerol > methanol > erythritol > xylitol. Silver catalysts were used as a cathode catalyst to fabricate alkaline fuel cells, since silver catalyst is almost inactive in the oxidation of polyhydric alcohols. Alkaline direct ethylene glycol fuel cells using silver as a cathode catalyst gave excellent performance because higher concentrations of fuel could be supplied to the anode.

A review on the performance and modelling of proton exchange membrane fuel cells

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

Boucetta, A., E-mail: abirboucetta@yahoo.fr; Ghodbane, H., E-mail: h.ghodbane@mselab.org; Bahri, M., E-mail: m.bahri@mselab.org

2016-07-25

Proton Exchange Membrane Fuel Cells (PEMFC), are energy efficient and environmentally friendly alternative to conventional energy conversion for various applications in stationary power plants, portable power device and transportation. PEM fuel cells provide low operating temperature and high-energy efficiency with near zero emission. A PEM fuel cell is a multiple distinct parts device and a series of mass, energy, transport through gas channels, electric current transport through membrane electrode assembly and electrochemical reactions at the triple-phase boundaries. These processes play a decisive role in determining the performance of the Fuel cell, so that studies on the phenomena of gas flowsmore » and the performance modelling are made deeply. This paper gives a comprehensive overview of the state of the art on the Study of the phenomena of gas flow and performance modelling of PEMFC.« less

Anion exchange membranes based on terminally crosslinked methyl morpholinium-functionalized poly(arylene ether sulfone)s

NASA Astrophysics Data System (ADS)

Kwon, Sohyun; Rao, Anil H. N.; Kim, Tae-Hyun

2018-01-01

Azide-assisted terminal crosslinking of methyl morpholinium-functionalized poly(arylene ether sulfone) block copolymers yields products (xMM-PESs) suitable for use as anion exchange membranes. By combining the advantages of bulky morpholinium conductors and our unique polymer network crosslinked only at the termini of the polymer chains, we can produce AEMs that after the crosslinking show minimal loss in conductivity, yet with dramatically reduced water uptake. Terminal crosslinking also significantly increases the thermal, mechanical and chemical stability levels of the membranes. A high ion conductivity of 73.4 mS cm-1 and low water uptake of 26.1% at 80 °C are obtained for the crosslinked membrane with higher amount of hydrophilic composition, denoted as xMM-PES-1.5-1. In addition, the conductivity of the crosslinked xMM-PES-1.5-1 membrane exceeds that of its non-crosslinked counterpart (denoted as MM-PES-1.5-1) above 60 °C at 95% relative humidity because of its enhanced water retention capacity caused by the terminally-crosslinked structure.

Electrically facilitated molecular transport. Analysis of the relative contributions of diffusion, migration, and electroosmosis to solute transport in an ion-exchange membrane.

PubMed

Bath, B D; White, H S; Scott, E R

2000-02-01

Electrically facilitated molecular transport in an ion-exchange membrane (Nafion, 1100 equiv wt) has been studied using a scanning electrochemical microscope. The transport rates of ferrocenylmethyltrimethylammonium (a cation), acetaminophen (a neutral molecule), and ascorbate (an anion) through approximately 120-micron-thick membranes were measured as a function of the iontophoretic current passed across the membrane (-1.0 to +1.0 A/cm2). Transport rates were analyzed by employing the Nernst-Planck equation, modified to account for electric field-driven convective transport. Excellent agreement between experimental and theoretical values of the molecular flux was obtained using a single fitting parameter for each molecule (electroosmotic drag coefficient). The electroosmotic velocity of the neutral molecule, acetaminophen, was shown to be a factor of approximately 500 larger than that of the cation ferrocenylmethyltrimethylammonium, a consequence of the electrostatic interaction of the cation with the negatively charged pore walls of the ion-exchange membrane. Electroosmotic transport of ascorbate occurred at a negligible rate due to repulsion of the anion by the cation-selective membrane. These results suggest that electroosmotic velocities of solute molecules are determined by specific chemical interactions of the permeant and membrane and may be very different from the average solution velocity. The efficiency of electroosmotic transport was also shown to be a function of the membrane thickness, in addition to membrane/solute interactions.

Electrolysis of a molten semiconductor

PubMed Central

Yin, Huayi; Chung, Brice; Sadoway, Donald R.

2016-01-01

Metals cannot be extracted by electrolysis of transition-metal sulfides because as liquids they are semiconductors, which exhibit high levels of electronic conduction and metal dissolution. Herein by introduction of a distinct secondary electrolyte, we reveal a high-throughput electro-desulfurization process that directly converts semiconducting molten stibnite (Sb2S3) into pure (99.9%) liquid antimony and sulfur vapour. At the bottom of the cell liquid antimony pools beneath cathodically polarized molten stibnite. At the top of the cell sulfur issues from a carbon anode immersed in an immiscible secondary molten salt electrolyte disposed above molten stibnite, thereby blocking electronic shorting across the cell. As opposed to conventional extraction practices, direct sulfide electrolysis completely avoids generation of problematic fugitive emissions (CO2, CO and SO2), significantly reduces energy consumption, increases productivity in a single-step process (lower capital and operating costs) and is broadly applicable to a host of electronically conductive transition-metal chalcogenides. PMID:27553525

Electrolysis of a molten semiconductor

DOE PAGES

Yin, Huayi; Chung, Brice; Sadoway, Donald R.

2016-08-24

Metals cannot be extracted by electrolysis of transition-metal sulfides because as liquids they are semiconductors, which exhibit high levels of electronic conduction and metal dissolution. Herein by introduction of a distinct secondary electrolyte, we reveal a high-throughput electro-desulfurization process that directly converts semiconducting molten stibnite (Sb 2S 3) into pure (99.9%) liquid antimony and sulfur vapour. At the bottom of the cell liquid antimony pools beneath cathodically polarized molten stibnite. At the top of the cell sulfur issues from a carbon anode immersed in an immiscible secondary molten salt electrolyte disposed above molten stibnite, thereby blocking electronic shorting across themore » cell. In conclusion, as opposed to conventional extraction practices, direct sulfide electrolysis completely avoids generation of problematic fugitive emissions (CO 2, CO and SO 2), significantly reduces energy consumption, increases productivity in a single-step process (lower capital and operating costs) and is broadly applicable to a host of electronically conductive transition-metal chalcogenides.« less

Electrolysis of a molten semiconductor.

PubMed

Yin, Huayi; Chung, Brice; Sadoway, Donald R

2016-08-24

Metals cannot be extracted by electrolysis of transition-metal sulfides because as liquids they are semiconductors, which exhibit high levels of electronic conduction and metal dissolution. Herein by introduction of a distinct secondary electrolyte, we reveal a high-throughput electro-desulfurization process that directly converts semiconducting molten stibnite (Sb2S3) into pure (99.9%) liquid antimony and sulfur vapour. At the bottom of the cell liquid antimony pools beneath cathodically polarized molten stibnite. At the top of the cell sulfur issues from a carbon anode immersed in an immiscible secondary molten salt electrolyte disposed above molten stibnite, thereby blocking electronic shorting across the cell. As opposed to conventional extraction practices, direct sulfide electrolysis completely avoids generation of problematic fugitive emissions (CO2, CO and SO2), significantly reduces energy consumption, increases productivity in a single-step process (lower capital and operating costs) and is broadly applicable to a host of electronically conductive transition-metal chalcogenides.

Electrolysis of a molten semiconductor

NASA Astrophysics Data System (ADS)

Yin, Huayi; Chung, Brice; Sadoway, Donald R.

2016-08-01

Metals cannot be extracted by electrolysis of transition-metal sulfides because as liquids they are semiconductors, which exhibit high levels of electronic conduction and metal dissolution. Herein by introduction of a distinct secondary electrolyte, we reveal a high-throughput electro-desulfurization process that directly converts semiconducting molten stibnite (Sb2S3) into pure (99.9%) liquid antimony and sulfur vapour. At the bottom of the cell liquid antimony pools beneath cathodically polarized molten stibnite. At the top of the cell sulfur issues from a carbon anode immersed in an immiscible secondary molten salt electrolyte disposed above molten stibnite, thereby blocking electronic shorting across the cell. As opposed to conventional extraction practices, direct sulfide electrolysis completely avoids generation of problematic fugitive emissions (CO2, CO and SO2), significantly reduces energy consumption, increases productivity in a single-step process (lower capital and operating costs) and is broadly applicable to a host of electronically conductive transition-metal chalcogenides.

Removal of pigments from molasses wastewater by combining micro-electrolysis with biological treatment method.

PubMed

Chen, Ben; Tian, Xiaofei; Yu, Lian; Wu, Zhenqiang

2016-12-01

Pigments in molasses wastewater (MWW) effluent, such as melanoidins, were considered as kinds of the most recalcitrant and hazardous colorant contaminants to the environment. In this study, de-coloring the MWW by a synergistic combination of micro-electrolysis with bio-treatment was performed. Aiming to a high de-colorization yield, levels of nutrition source supplies, MWW dilution ratio, and micro-electrolysis reaction time were optimized accordingly. For a diluted (50 %, v/v) MWW, an maximum overall de-colorization yield (97.1 ± 0.5 %, for absorbance at 475 nm) was achieved through the bio-electrolysis treatment. In electrolysis bio-treatment, the positive effect of micro-electrolysis was also revealed by a promoted growth of fungal biomass as well as activities of ligninolytic enzymes. Activities of lignin peroxidase, manganese peroxidase, and laccase were promoted by 111.2, 103.9, and 7.7 %, respectively. This study also implied that the bio-treatment and the micro-electrolysis had different efficiencies on removal of pigments with distinct polarities.

Kinetics of nitrate and perchlorate reduction in ion exchange brine using the membrane biofilm reactor (MBfR)

EPA Science Inventory

Several sources of bacterial inocula were tested for their ability to reduce nitrate and perchlorate in synthetic ion-exchange spent brine (3-4.5% salinity) using a hydrogen-based membrane biofilm reactor (MBfR). Nitrate and perchlorate removal fluxes reached as high as 5.4 g N ...

LARGE-SCALE HYDROGEN PRODUCTION FROM NUCLEAR ENERGY USING HIGH TEMPERATURE ELECTROLYSIS

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

James E. O'Brien

2010-08-01

Hydrogen can be produced from water splitting with relatively high efficiency using high-temperature electrolysis. This technology makes use of solid-oxide cells, running in the electrolysis mode to produce hydrogen from steam, while consuming electricity and high-temperature process heat. When coupled to an advanced high temperature nuclear reactor, the overall thermal-to-hydrogen efficiency for high-temperature electrolysis can be as high as 50%, which is about double the overall efficiency of conventional low-temperature electrolysis. Current large-scale hydrogen production is based almost exclusively on steam reforming of methane, a method that consumes a precious fossil fuel while emitting carbon dioxide to the atmosphere. Demandmore » for hydrogen is increasing rapidly for refining of increasingly low-grade petroleum resources, such as the Athabasca oil sands and for ammonia-based fertilizer production. Large quantities of hydrogen are also required for carbon-efficient conversion of biomass to liquid fuels. With supplemental nuclear hydrogen, almost all of the carbon in the biomass can be converted to liquid fuels in a nearly carbon-neutral fashion. Ultimately, hydrogen may be employed as a direct transportation fuel in a “hydrogen economy.” The large quantity of hydrogen that would be required for this concept should be produced without consuming fossil fuels or emitting greenhouse gases. An overview of the high-temperature electrolysis technology will be presented, including basic theory, modeling, and experimental activities. Modeling activities include both computational fluid dynamics and large-scale systems analysis. We have also demonstrated high-temperature electrolysis in our laboratory at the 15 kW scale, achieving a hydrogen production rate in excess of 5500 L/hr.« less

Non-covalent bonding interaction of surfactants with functionalized carbon nanotubes in proton exchange membranes for fuel cell applications.

PubMed

Sayeed, M Abu; Kim, Young Ho; Park, Younjin; Gopalan, A I; Lee, Kwang-Pill; Choi, Sang-June

2013-11-01

Dispersion of functionalized multiwalled carbon nanotubes (MWCNTs) in proton exchange membranes (PEMs) was conducted via non-covalent bonding between benzene rings of various surfactants and functionalized MWCNTs. In the solution casting method, dispersion of functionalized MWCNTs in PEMs such as Nafion membranes is a critical issue. In this study, 1 wt.% pristine MWCNTs (p-MWCNTs) and oxidized MWCNTs (ox-MWCNTs) were reinforced in Nafion membranes by adding 0.1-0.5 wt.% of a surfactant such as benzalkonium chloride (BKC) as a cationic surfactant with a benzene ring, Tween-80 as a nonanionic surfactant without a benzene ring, sodium dodecylsulfonate (SDS) as an anionic surfactant without a benzene ring, or sodium dodecylben-zenesulfonate (SDBS) as an anionic surfactant with a benzene ring and their effects on the dispersion of nanocomposites were then observed. Among these surfactants, those with benzene rings such as BKC and SDBS produced enhanced dispersion via non-covalent bonding interaction between CNTs and surfactants. Specifically, the surfactants were adsorbed onto the surface of functionalized MWCNTs, where they prevented re-aggregation of MWCNTs in the nanocomposites. Furthermore, the prepared CNTs reinforced nanocomposite membranes showed reduced methanol uptake values while the ion exchange capacity values were maintained. The enhanced properties, including thermal property of the CNTs reinforced PEMs with surfactants, could be applicable to fuel cell applications.

Assessing the influence of side-chain and main-chain aromatic benzyltrimethyl ammonium on anion exchange membranes.

PubMed

Li, Xiuhua; Nie, Guanghui; Tao, Jinxiong; Wu, Wenjun; Wang, Liuchan; Liao, Shijun

2014-05-28

3,3'-Di(4″-methyl-phenyl)-4,4'-difluorodiphenyl sulfone (DMPDFPS), a new monomer with two pendent benzyl groups, was easily prepared by Suzuki coupling reaction in high yield. A series of side-chain type ionomers (PAES-Qs) containing pendant side-chain benzyltrimethylammonium groups, which linked to the backbone by alkaline resisting conjugated C-C bonds, were synthesized via polycondensation, bromination, followed by quaternization and alkalization. To assess the influence of side-chain and main-chain aromatic benzyltrimethylammonium on anion exchange membranes (AEMs), the main-chain type ionomers (MPAES-Qs) with the same backbone were synthesized following the similar procedure. GPC and (1)H NMR results indicate that the bromination shows no reaction selectivity of polymer configurations and ionizations of the side-chain type polymers display higher conversions than that of the main-chain type ones do. These two kinds of AEMs were evaluated in terms of ion exchange capacity (IEC), water uptake, swelling ratio, λ, volumetric ion exchange capacity (IECVwet), hydroxide conductivity, mechanical and thermal properties, and chemical stability, respectively. The side-chain type structure endows AEMs with lower water uptake, swelling ratio and λ, higher IECVwet, much higher hydroxide conductivity, more robust dimensional stability, mechanical and thermal properties, and higher stability in hot alkaline solution. The side-chain type cationic groups containing molecular configurations have the distinction of being practical AEMs and membrane electrode assemblies of AEMFCs.

Coupled electro-thermal field in a high current electrolysis cell or liquid metal batteries

PubMed Central

Cai, Liwei; Ni, Haiou; Lu, Gui-Min; Yu, Jian-Guo

2018-01-01

Coupled electro-thermal field exists widely in chemical batteries and electrolysis industry. In this study, a three-dimensional numerical model, which is based on the finite-element software ANSYS, has been built to simulate the electro-thermal field in a magnesium electrolysis cell. The adjustment of the relative position of the anode and cathode can change the energy consumption of the magnesium electrolysis process significantly. Besides, the current intensity has a nonlinear effect on heat balance, and the effects of heat transfer coefficients, electrolysis and air temperature on the heat balance have been released to maintain the thermal stability in a magnesium electrolysis cell. The relationship between structure as well as process parameters and electro-thermal field has been obtained and the simulation results can provide experience for the scale-up design in liquid metal batteries. PMID:29515848

Synthesis and Characterization of Perfluoro Quaternary Ammonium Ion Exchange Membranes for Fuel Cell Applications

DTIC Science & Technology

2012-01-01

complex fuels (2, 4-6). Current research on alkali fuel cells is primarily focused on the development of a solid polymer anion exchange membrane ( AEM ...a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. a...research focus the last few decades due to their high power density and low emissions when operating with hydrogen fuel (1-3). Recently however

Phosphoric acid functionalized pre-sintered meso-silica for high temperature proton exchange membrane fuel cells.

PubMed

Zeng, Jie; He, Beibei; Lamb, Krystina; De Marco, Roland; Shen, Pei Kang; Jiang, San Ping

2013-05-21

An inorganic proton exchange membrane based on sintered mesoporous silica and phosphoric acid was developed with a high proton conductivity of 0.06 S cm(-1) at 200 °C, achieving an excellent power output of 689 mW cm(-2) in H2 at 190 °C and 200 mW cm(-2) in methanol at 200 °C with no external humidification.

Improved Durability of SOEC Stacks for High Temperature Electrolysis

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

James E. O'Brien; Robert C. O'Brien; Xiaoyu Zhang

2013-01-01

High temperature steam electrolysis is a promising technology for efficient and sustainable large-scale hydrogen production. Solid oxide electrolysis cells (SOECs) are able to utilize high temperature heat and electric power from advanced high-temperature nuclear reactors or renewable sources to generate carbon-free hydrogen at large scale. However, long term durability of SOECs needs to be improved significantly before commercialization of this technology can be realized. A degradation rate of 1%/khr or lower is proposed as a threshold value for commercialization of this technology. Solid oxide electrolysis stack tests have been conducted at Idaho National Laboratory to demonstrate recent improvements in long-termmore » durability of SOECs. Electrolyte-supported and electrode-supported SOEC stacks were provided by Ceramatec Inc. and Materials and Systems Research Inc. (MSRI), respectively, for these tests. Long-term durability tests were generally operated for a duration of 1000 hours or more. Stack tests based on technologies developed at Ceramatec and MSRI have shown significant improvement in durability in the electrolysis mode. Long-term degradation rates of 3.2%/khr and 4.6%/khr were observed for MSRI and Ceramatec stacks, espectively. One recent Ceramatec stack even showed negative degradation (performance improvement) over 1900 hours of operation. Optimization of electrode materials, interconnect coatings, and electrolyte-electrode interface microstructures contribute to better durability of SOEC stacks.« less

Installation of Ohio's First Electrolysis-Based Hydrogen Fueling Station

NASA Technical Reports Server (NTRS)

Scheidegger, Brianne T.; Lively, Michael L.

2012-01-01

This paper describes progress made towards the installation of a hydrogen fueling station in Northeast Ohio. In collaboration with several entities in the Northeast Ohio area, the NASA Glenn Research Center is installing a hydrogen fueling station that uses electrolysis to generate hydrogen on-site. The installation of this station is scheduled for the spring of 2012 at the Greater Cleveland Regional Transit Authority s Hayden bus garage in East Cleveland. This will be the first electrolysis-based hydrogen fueling station in Ohio.

Principles and implementations of electrolysis systems for water splitting

DOE PAGES

Xiang, Chengxiang; Papadantonakis, Kimberly M.; Lewis, Nathan S.

2016-02-12

Efforts to develop renewable sources of carbon-neutral fuels have brought a renewed focus to research and development of sunlight-driven water-splitting systems. Electrolysis of water to produce H 2 and O 2 gases is the foundation of such systems, is conceptually and practically simple, and has been practiced both in the laboratory and industrially for many decades. In this Focus article, the fundamentals of water splitting and practices which distinguish commercial water-electrolysis systems from simple laboratory-scale demonstrations are described.

High Performance, Low Cost Hydrogen Generation from Renewable Energy

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

Ayers, Katherine; Dalton, Luke; Roemer, Andy

Renewable hydrogen from proton exchange membrane (PEM) electrolysis is gaining strong interest in Europe, especially in Germany where wind penetration is already at critical levels for grid stability. For this application as well as biogas conversion and vehicle fueling, megawatt (MW) scale electrolysis is required. Proton has established a technology roadmap to achieve the necessary cost reductions and manufacturing scale up to maintain U.S. competitiveness in these markets. This project represents a highly successful example of the potential for cost reduction in PEM electrolysis, and provides the initial stack design and manufacturing development for Proton’s MW scale product launch. Themore » majority of the program focused on the bipolar assembly, from electrochemical modeling to subscale stack development through prototyping and manufacturing qualification for a large active area cell platform. Feasibility for an advanced membrane electrode assembly (MEA) with 50% reduction in catalyst loading was also demonstrated. Based on the progress in this program and other parallel efforts, H2A analysis shows the status of PEM electrolysis technology dropping below $3.50/kg production costs, exceeding the 2015 target.« less

Radiolytic preparation of ETFE and PFA based anion exchange membranes for alkaline fuel cell

NASA Astrophysics Data System (ADS)

Ko, Beom-Seok; Sohn, Joon-Yong; Nho, Young-Chang; Shin, Junhwa

2011-11-01

In this study, a versatile monomer, vinylbenzyl chloride (VBC) was radiolytically grafted onto a partially fluorinated ETFE and perfluorinated polymer PFA films. The VBC grafted films were treated with trimethylamine to prepare the alkaline anion exchange membranes (AAEMs). No significant differences in the ion exchange capacities and water uptakes were observed between the ETFE and PFA based AAEMs with similar degree of grafting (DOG). However, the distribution patterns of the graft chains over the cross-section of the ETFE and PFA based AAEMs were found to be quite different; the even distribution was observed from the ETFE based AAEMs while the uneven distribution was observed from the PFA based AAEMs. It was also found that the PFA based AAEMs have the higher ionic conductivity and chemical stability, compared to the ETFE based AAEMs.

H3PO4 imbibed polyacrylamide-graft-chitosan frameworks for high-temperature proton exchange membranes

NASA Astrophysics Data System (ADS)

Yuan, Shuangshuang; Tang, Qunwei; He, Benlin; Chen, Haiyan; Li, Qinghua; Ma, Chunqing; Jin, Suyue; Liu, Zhichao

2014-03-01

Proton exchange membrane (PEM), transferring protons from anode to cathode, is a key component in a PEM fuel cell. In the current work, a new class of PEMs are synthesized benefiting from the imbibition behavior of three-dimensional (3D) polyacrylamide-graft-chitosan (PAAm-graft-chitosan) frameworks to H3PO4 aqueous solution. Interconnected 3D framework of PAAm-graft-chitosan provides tremendous space for holding proton-conducting H3PO4. The highest anhydrous proton conductivity of 0.13 S cm-1 at 165 °C is obtained. A fuel cell using a thick membrane as a PEM showed a peak power density of 405 mW cm-2 with O2 and H2 as the oxidant and fuel, respectively. Results indicate that the interconnected 3D framework provides superhighway for proton conduction. The valued merits on anhydrous proton conductivity, huge H3PO4 loading, and easy synthesis promise the new membranes to be good alternatives as high-temperature PEMs.

A pulse NMR study of water exchange across the erythrocyte membrane

NASA Astrophysics Data System (ADS)

Lahajnar, G.

1993-03-01

A pulse nuclear magnetic resonance (NMR) technique is employed to study the temperature dependence (5-40°C) of the diffusional water exchange time τexch for normal and p-hydroxymercuribenzoate ( p-HMB) treated bovine erythrocytes. The Arrhenius plot of τexch for normal erythrocytes implies the activation energy Ea of 20.4 kJ/mol, similar to that for self-diffusion of water ( Ea = 19.3 - 20.1 kJ/mol), and the value τexch of 12.5 ms at 20°C corresponds to the cell membrane diffusional water permeability coefficient P d of 3.6 × 10 -3 cm/s. The data for p-HMB treated cells display lengthening of τexch (i.e., τexch = 17.3 ms at 20°C) and increased E a of 29.0 kJ/mol. This E a value and a permeability coefficient P d of 2.6 × 10 -3 cm/s at 20°C, if compared to corresponding data for artificial lipid bilayer membranes, indicate either incomplete closure of the specialized water-selective protein channels on binding of p-HMB to their SH-groups, or complete channel closure plus new leaks.

Modelling heat and mass transfer in a membrane-based air-to-air enthalpy exchanger

NASA Astrophysics Data System (ADS)

Dugaria, S.; Moro, L.; Del, D., Col

2015-11-01

The diffusion of total energy recovery systems could lead to a significant reduction in the energy demand for building air-conditioning. With these devices, sensible heat and humidity can be recovered in winter from the exhaust airstream, while, in summer, the incoming air stream can be cooled and dehumidified by transferring the excess heat and moisture to the exhaust air stream. Membrane based enthalpy exchangers are composed by different channels separated by semi-permeable membranes. The membrane allows moisture transfer under vapour pressure difference, or water concentration difference, between the two sides and, at the same time, it is ideally impermeable to air and other contaminants present in exhaust air. Heat transfer between the airstreams occurs through the membrane due to the temperature gradient. The aim of this work is to develop a detailed model of the coupled heat and mass transfer mechanisms through the membrane between the two airstreams. After a review of the most relevant models published in the scientific literature, the governing equations are presented and some simplifying assumptions are analysed and discussed. As a result, a steady-state, two-dimensional finite difference numerical model is setup. The developed model is able to predict temperature and humidity evolution inside the channels. Sensible and latent heat transfer rate, as well as moisture transfer rate, are determined. A sensitive analysis is conducted in order to determine the more influential parameters on the thermal and vapour transfer.

Electroosmosis through a Cation-Exchange Membrane: Effect of an ac Perturbation on the Electroosmotic Flow.

PubMed

Barragán; Ruíz Bauzá C

2000-10-15

Electroosmosis experiments through a cation-exchange membrane have been performed using NaCl solutions in different experimental situations. The influence of an alternating (ac) sinusoidal perturbation, of known angular frequency and small amplitude, superimposed to the usual applied continuous (dc) signal on the electroosmotic flow has been studied. The experimental results show that the presence of the ac perturbation affects the electroosmotic flow value, depending on the frequency of the ac signal and on the solution stirring conditions. In the frequency range studied, two regions have been observed where the electroosmotic flow reaches a maximum value: one at low frequencies ( approximately Hz); and another at frequencies of the order of kHz. These regions could be related to membrane relaxation phenomena. Copyright 2000 Academic Press.

In-situ membrane hydration measurement of proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Lai, Yeh-Hung; Fly, Gerald W.; Clapham, Shawn

2015-01-01

Achieving proper membrane hydration control is one of the most critical aspects of PEM fuel cell development. This article describes the development and application of a novel 50 cm2 fuel cell device to study the in-situ membrane hydration by measuring the through-thickness membrane swelling via an array of linear variable differential transducers. Using this setup either as an air/air (dummy) cell or as a hydrogen/air (operating) cell, we performed a series of hydration and dehydration experiments by cycling the RH of the inlet gas streams at 80 °C. From the linear relationship between the under-the-land swelling and the over-the-channel water content, the mechanical constraint within the fuel cell assembly can suppress the membrane water uptake by 11%-18%. The results from the air/air humidity cycling test show that the membrane can equilibrate within 120 s for all RH conditions and that membrane can reach full hydration at a RH higher than 140% in spite of the use of a liquid water impermeable Carbel MP30Z microporous layer. This result confirms that the U.S. DOE's humidity cycling mechanical durability protocol induces sufficient humidity swings to maximize hygrothermal mechanical stresses. This study shows that the novel experimental technique can provide a robust and accurate means to study the in-situ hydration of thin membranes subject to a wide range of fuel cell conditions.

[Measurement of pancreatic microcirculation using hydrogen gas generated by electrolysis in dogs].

PubMed

Nishiwaki, H; Satake, K; Ko, I; Tanaka, H; Kanazawa, G; Nagai, Y; Umeyama, K

1986-11-01

Measurements of pancreatic microflow were investigated using hydrogen gas generated by electrolysis in dog. After laparatomy under general anesthesia, uncinate process of the pancreas was punctured by a needle electrode for electrolysis and determination of hydrogen gas. The consecutive measurements of pancreatic microflow revealed the good reproducibility at the same point of the pancreas. The simultaneous measurements of pancreatic microflow by electrolysis and pancreatic tissue blood flow by H2 inhalation method were carried out at the same point of the pancreas. Correlation analysis of both measurements revealed coefficient of 0.751 and a significant relationship was observed (p less than 0.05). However, the value was a little higher in pancreatic microflow as compared with pancreatic tissue blood flow. Pancreatic microflow and pancreatic exocrine secretion increased after intravenous administration of Dopamine and Secretin (10 micrograms/kg/min). It is concluded that the measurement of pancreatic microflow by hydrogen gas generated by electrolysis is a useful method on understanding the microcirculation of the pancreas.

Enhanced Flux and Electrochemical Cleaning of Silicate Scaling on Carbon Nanotube-Coated Membrane Distillation Membranes Treating Geothermal Brines

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

Tang, Li; Iddya, Arpita; Zhu, Xiaobo

The desalination of inland brackish groundwater offers the opportunity to provide potable drinking water to residents and industrial cooling water to industries located in arid regions. Geothermal brines are used to generate electricity, but often contain high concentrations of dissolved salt. Here in this paper, we demonstrate how the residual heat left in spent geothermal brines can be used to drive a membrane distillation (MD) process and recover desalinated water. Porous polypropylene membranes were coated with a carbon nanotube (CNT)/poly(vinyl alcohol) layer, resulting in composite membranes having a binary structure that combines the hydrophobic properties critical for MD with themore » hydrophilic and conductive properties of the CNTs. We demonstrate that the addition of the CNT layer increases membrane flux due to enhanced heat transport from the bulk feed to the membrane surface, a result of CNT's high thermal transport properties. Furthermore, we show how hydroxide ion generation, driven by water electrolysis on the electrically conducting membrane surface, can be used to efficiently dissolve silicate scaling that developed during the process of desalinating the geothermal brine, negating the need for chemical cleaning.« less

Enhanced Flux and Electrochemical Cleaning of Silicate Scaling on Carbon Nanotube-Coated Membrane Distillation Membranes Treating Geothermal Brines

DOE PAGES

Tang, Li; Iddya, Arpita; Zhu, Xiaobo; ...

2017-10-13

The desalination of inland brackish groundwater offers the opportunity to provide potable drinking water to residents and industrial cooling water to industries located in arid regions. Geothermal brines are used to generate electricity, but often contain high concentrations of dissolved salt. Here in this paper, we demonstrate how the residual heat left in spent geothermal brines can be used to drive a membrane distillation (MD) process and recover desalinated water. Porous polypropylene membranes were coated with a carbon nanotube (CNT)/poly(vinyl alcohol) layer, resulting in composite membranes having a binary structure that combines the hydrophobic properties critical for MD with themore » hydrophilic and conductive properties of the CNTs. We demonstrate that the addition of the CNT layer increases membrane flux due to enhanced heat transport from the bulk feed to the membrane surface, a result of CNT's high thermal transport properties. Furthermore, we show how hydroxide ion generation, driven by water electrolysis on the electrically conducting membrane surface, can be used to efficiently dissolve silicate scaling that developed during the process of desalinating the geothermal brine, negating the need for chemical cleaning.« less

Analysis performance of proton exchange membrane fuel cell (PEMFC)

NASA Astrophysics Data System (ADS)

Mubin, A. N. A.; Bahrom, M. H.; Azri, M.; Ibrahim, Z.; Rahim, N. A.; Raihan, S. R. S.

2017-06-01

Recently, the proton exchange membrane fuel cell (PEMFC) has gained much attention to the technology of renewable energy due to its mechanically ideal and zero emission power source. PEMFC performance reflects from the surroundings such as temperature and pressure. This paper presents an analysis of the performance of the PEMFC by developing the mathematical thermodynamic modelling using Matlab/Simulink. Apart from that, the differential equation of the thermodynamic model of the PEMFC is used to explain the contribution of heat to the performance of the output voltage of the PEMFC. On the other hand, the partial pressure equation of the hydrogen is included in the PEMFC mathematical modeling to study the PEMFC voltage behaviour related to the input variable input hydrogen pressure. The efficiency of the model is 33.8% which calculated by applying the energy conversion device equations on the thermal efficiency. PEMFC’s voltage output performance is increased by increasing the hydrogen input pressure and temperature.

The Effect of Ambient Carbon Dioxide on Anion-Exchange Membrane Fuel Cells.

PubMed

Ziv, Noga; Mustain, William E; Dekel, Dario R

2018-04-09

Over the past 10 years, there has been a surge of interest in anion-exchange membrane fuel cells (AEMFCs) as a potentially lower cost alternative to proton-exchange membrane fuel cells (PEMFCs). Recent work has shown that AEMFCs achieve nearly identical performance to that of state-of-the-art PEMFCs; however, much of that data has been collected while feeding CO 2 -free air or pure oxygen to the cathode. Usually, removing CO 2 from the oxidant is done to avoid the detrimental effect of CO 2 on AEMFC performance, through carbonation, whereby CO 2 reacts with the OH - anions to form HCO 3 - and CO 3 2- . In spite of the crucial importance of this topic for the future development and commercialization of AEMFCs, unfortunately there have been very few investigations devoted to this phenomenon and its effects. Much of the data available is widely spread out and there currently does not exist a resource that researchers in the field, or those looking to enter the field, can use as a reference text that explains the complex influence of CO 2 and HCO 3 - /CO 3 2- on all aspects of AEMFC performance. The purpose of this Review is to summarize the experimental and theoretical work reported to date on the effect of ambient CO 2 on AEMFCs. This systematic Review aims to create a single comprehensive account of what is known regarding how CO 2 behaves in AEMFCs, to date, as well as identify the most important areas for future work in this field. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phosphate barrier on pore-filled cation-exchange membrane for blocking complexing ions in presence of non-complexing ions

NASA Astrophysics Data System (ADS)

Chavan, Vivek; Agarwal, Chhavi; Shinde, Rakesh N.

2018-06-01

In present work, an approach has been used to form a phosphate groups bearing surface barrier on a cation-exchange membrane (CEM). Using optimized conditions, the phosphate bearing monomer bis[2-(methacryloyloxy)ethyl] phosphate has been grafted on the surface of the host poly(ethersulfone) membranes using UV light induced polymerization. The detailed characterizations have shown that less than a micron layer of phosphate barrier is formed without disturbing the original microporous structure of the host membrane. The pores of thus formed membrane have been blocked by cationic-gel formed by in situ UV-initiator induced polymerization of 2-acrylamido-2-methyl-1-propane sulphonic acid along with crosslinker ethylene glycol dimethacrylate in the pores of the membrane. UV-initiator is required for pore-filling as UV light would not penetrate the interior matrix of the membrane. The phosphate functionalized barrier membrane has been examined for permselectivity using a mixture of representative complexing Am3+ ions and non-complexing Cs+ ions. This experiment has demonstrated that complex forming Am3+ ions are blocked by phosphate barrier layer while non-complexing Cs+ ions are allowed to pass through the channels formed by the crosslinked cationic gel.

Electrolysis Bubbles Make Waterflow Visible

NASA Technical Reports Server (NTRS)

Schultz, Donald F.

1990-01-01

Technique for visualization of three-dimensional flow uses tiny tracer bubbles of hydrogen and oxygen made by electrolysis of water. Strobe-light photography used to capture flow patterns, yielding permanent record that is measured to obtain velocities of particles. Used to measure simulated mixing turbulence in proposed gas-turbine combustor and also used in other water-table flow tests.

Water electrolysis

NASA Technical Reports Server (NTRS)

Schubert, Franz H. (Inventor); Grigger, David J. (Inventor)

1992-01-01

This disclosure is directed to an electrolysis cell forming hydrogen and oxygen at space terminals. The anode terminal is porous and able to form oxygen within the cell and permit escape of the gaseous oxygen through the anode and out through a flow line in the presence of backpressure. Hydrogen is liberated in the cell at the opposing solid metal cathode which is permeable to hydrogen but not oxygen so that the migratory hydrogen formed in the cell is able to escape from the cell. The cell is maintained at an elevated pressure so that the oxygen liberated by the cell is delivered at elevated pressure without pumping to raise the pressure of the oxygen.

Desalination and hydrogen, chlorine, and sodium hydroxide production via electrophoretic ion exchange and precipitation.

PubMed

Shkolnikov, Viktor; Bahga, Supreet S; Santiago, Juan G

2012-08-28

We demonstrate and analyze a novel desalination method which works by electrophoretically replacing sodium and chloride in feed salt water with a pair of ions, calcium and carbonate, that react and precipitate out. The resulting calcium carbonate precipitate is benign to health, and can be filtered or settled out, yielding low ionic strength product water. The ion exchange and precipitation employs self-sharpening interfaces induced by movement of multiple ions in an electric field to prevent contamination of the product water. Simultaneously, the electrolysis associated with the electromigration produces hydrogen gas, chlorine gas, and sodium hydroxide. We conducted an experimental study of this method's basic efficacy to desalinate salt water from 100 to 600 mol m(-3) sodium chloride. We also present physicochemical models of the process, and analyze replacement reagents consumption, permeate recovery ratio, and energy consumption. We hypothesize that the precipitate can be recycled back to replacement reagents using the well-known, commercially implemented Solvay process. We show that the method's permeate recovery ratio is 58% to 46%, which is on par with that of reverse osmosis. We show that the method's energy consumption requirement over and above that necessary to generate electrolysis is 3 to 10 W h l(-1), which is on par with the energy consumed by state-of-the-art desalination methods. Furthermore, the method operates at ambient temperature and pressure, and uses no specialized membranes. The process may be feasible as a part of a desalination-co-generation facility: generating fresh water, hydrogen and chlorine gas, and sodium hydroxide.

Activity targets for nanostructured platinum-group-metal-free catalysts in hydroxide exchange membrane fuel cells.

PubMed

Setzler, Brian P; Zhuang, Zhongbin; Wittkopf, Jarrid A; Yan, Yushan

2016-12-06

Fuel cells are the zero-emission automotive power source that best preserves the advantages of gasoline automobiles: low upfront cost, long driving range and fast refuelling. To make fuel-cell cars a reality, the US Department of Energy has set a fuel cell system cost target of US$30 kW -1 in the long-term, which equates to US$2,400 per vehicle, excluding several major powertrain components (in comparison, a basic, but complete, internal combustion engine system costs approximately US$3,000). To date, most research for automotive applications has focused on proton exchange membrane fuel cells (PEMFCs), because these systems have demonstrated the highest power density. Recently, however, an alternative technology, hydroxide exchange membrane fuel cells (HEMFCs), has gained significant attention, because of the possibility to use stable platinum-group-metal-free catalysts, with inherent, long-term cost advantages. In this Perspective, we discuss the cost profile of PEMFCs and the advantages offered by HEMFCs. In particular, we discuss catalyst development needs for HEMFCs and set catalyst activity targets to achieve performance parity with state-of-the-art automotive PEMFCs. Meeting these targets requires careful optimization of nanostructures to pack high surface areas into a small volume, while maintaining high area-specific activity and favourable pore-transport properties.

Activity targets for nanostructured platinum-group-metal-free catalysts in hydroxide exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Setzler, Brian P.; Zhuang, Zhongbin; Wittkopf, Jarrid A.; Yan, Yushan

2016-12-01

Fuel cells are the zero-emission automotive power source that best preserves the advantages of gasoline automobiles: low upfront cost, long driving range and fast refuelling. To make fuel-cell cars a reality, the US Department of Energy has set a fuel cell system cost target of US$30 kW-1 in the long-term, which equates to US$2,400 per vehicle, excluding several major powertrain components (in comparison, a basic, but complete, internal combustion engine system costs approximately US$3,000). To date, most research for automotive applications has focused on proton exchange membrane fuel cells (PEMFCs), because these systems have demonstrated the highest power density. Recently, however, an alternative technology, hydroxide exchange membrane fuel cells (HEMFCs), has gained significant attention, because of the possibility to use stable platinum-group-metal-free catalysts, with inherent, long-term cost advantages. In this Perspective, we discuss the cost profile of PEMFCs and the advantages offered by HEMFCs. In particular, we discuss catalyst development needs for HEMFCs and set catalyst activity targets to achieve performance parity with state-of-the-art automotive PEMFCs. Meeting these targets requires careful optimization of nanostructures to pack high surface areas into a small volume, while maintaining high area-specific activity and favourable pore-transport properties.

Effect of Divalent Cations on RED Performance and Cation Exchange Membrane Selection to Enhance Power Densities.

PubMed

Rijnaarts, Timon; Huerta, Elisa; van Baak, Willem; Nijmeijer, Kitty

2017-11-07

Reverse electrodialysis (RED) is a membrane-based renewable energy technology that can harvest energy from salinity gradients. The anticipated feed streams are natural river and seawater, both of which contain not only monovalent ions but also divalent ions. However, RED using feed streams containing divalent ions experiences lower power densities because of both uphill transport and increased membrane resistance. In this study, we investigate the effects of divalent cations (Mg 2+ and Ca 2+ ) on RED and demonstrate the mitigation of those effects using both novel and existing commercial cation exchange membranes (CEMs). Monovalent-selective Neosepta CMS is known to block divalent cations transport and can therefore mitigate reductions in stack voltage. The new multivalent-permeable Fuji T1 is able to transport divalent cations without a major increase in resistance. Both strategies significantly improve power densities compared to standard-grade CEMs when performing RED using streams containing divalent cations.

Hydrogen production profiles using furans in microbial electrolysis cells.

PubMed

Catal, Tunc; Gover, Tansu; Yaman, Bugra; Droguetti, Jessica; Yilancioglu, Kaan

2017-06-01

Microbial electrochemical cells including microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are novel biotechnological tools that can convert organic substances in wastewater or biomass into electricity or hydrogen. Electroactive microbial biofilms used in this technology have ability to transfer electrons from organic compounds to anodes. Evaluation of biofilm formation on anode is crucial for enhancing our understanding of hydrogen generation in terms of substrate utilization by microorganisms. In this study, furfural and hydroxymethylfurfural (HMF) were analyzed for hydrogen generation using single chamber membrane-free MECs (17 mL), and anode biofilms were also examined. MECs were inoculated with mixed bacterial culture enriched using chloroethane sulphonate. Hydrogen was succesfully produced in the presence of HMF, but not furfural. MECs generated similar current densities (5.9 and 6 mA/cm 2 furfural and HMF, respectively). Biofilm samples obtained on the 24th and 40th day of cultivation using aromatic compounds were evaluated by using epi-fluorescent microscope. Our results show a correlation between biofilm density and hydrogen generation in single chamber MECs.

Understanding ion and solvent transport in anion exchange membranes under humidified conditions

NASA Astrophysics Data System (ADS)

Sarode, Himanshu

Anion exchange membranes (AEM) have been studied for more than a decade for potential applications in low temperature fuel cells and other electrochemical devices. They offer the advantage of faster reaction kinetics under alkaline conditions and ability to perform without costly platinum catalyst. Inherently slow diffusion of hydroxide ions compared to protons is a primary reason for synthesizing and studying the ion transport properties in AEMs. The aim of this thesis is to understand ion transport in novel AEMs using Pulse Gradient stimulated Spin Echo Nuclear Magnetic Resonance technique (PGSE NMR), water uptake, ionic conductivity, Small Angle X-ray Scattering (SAXS) etc. All experiments were performed under humidified conditions (80--95% relative humidity) and fuel cell operating temperatures of 30--90°C. In this work, the NMR tube design was modified for humidifying the entire NMR tube evenly from our previous design. We have developed a new protocol for replacing caustic hydroxide with harmless fluoride or bicarbonate ions for 19F and 13 C NMR diffusion experiments. After performing these NMR experiments, we have obtained in-depth understanding of the morphology linked ion transport in AEMs. We have obtained the highest fluoride self-diffusion coefficient of > 1 x 10-5 cm2/sec ( 55°C) for ETFE-g-PVBTMA membrane which is a result of low tortuosity of 1 obtained for the membrane. This faster fluoride transport combined with low tortuosity of the membrane resulted in > 100mS/cm hydroxide conductivity for the membrane. Polycyclooctene (PCOE) based triblock copolymers are also studied for in-depth understanding of molecular weight, IEC, mechanical and transport properties. Effect of melting temperature of PCOE has favorable effect on increasing ion conductivity and lowering activation energy. Mechanical properties of these types of membranes were studied showing detrimental effect of water plasticization which results in unsuitable mechanical properties

Effects of electrolysis time and electric potential on chlorine generation of electrolyzed deep ocean water.

PubMed

Hsu, Guoo-Shyng Wang; Lu, Yi-Fa; Hsu, Shun-Yao

2017-10-01

Electrolyzed water is a sustainable disinfectant, which can comply with food safety regulations and is environmentally friendly. A two-factor central composite design was adopted for studying the effects of electrolysis time and electric potential on the chlorine generation efficiency of electrolyzed deep ocean water (DOW). DOW was electrolyzed in a glass electrolyzing cell equipped with platinum-plated titanium anode and cathode. The results showed that chlorine concentration reached maximal level in the batch process. Prolonged electrolysis reduced chlorine concentration in the electrolyte and was detrimental to electrolysis efficiency, especially under high electric potential conditions. Therefore, the optimal choice of electrolysis time depends on the electrolyzable chloride in DOW and cell potential adopted for electrolysis. The higher the electric potential, the faster the chlorine level reaches its maximum, but the lower the electric efficiency will be. Copyright © 2016. Published by Elsevier B.V.

Transport properties of proton-exchange membranes: Effect of supercritical-fluid processing and chemical functionality

NASA Astrophysics Data System (ADS)

Pulido Ayazo

NafionRTM membranes commonly used in direct methanol fuel cells (DMFC), are tipically limited by high methanol permeability (also known as the cross-over limitation). These membranes have phase segregated sulfonated ionic domains in a perfluorinated backbone, which makes processing challenging and limited by phase equilibria considerations. This study used supercritical fluids (SCFs) as a processing alternative, since the gas-like mass transport properties of SCFs allow a better penetration into the membranes and the use of polar co-solvents influenced their morphology, fine-tuning the physical and transport properties in the membrane. Measurements of methanol permeability and proton conductivity were performed to the NafionRTM membranes processed with SCFs at 40ºC and 200 bar and the co-solvents as: acetone, tetrahydrofuran (THF), isopropyl alcohol, HPLC-grade water, acetic acid, cyclohexanone. The results obtained for the permeability data were of the order of 10 -8-10-9 cm2/s, two orders of magnitude lower than unprocessed Nafion. Proton conductivity results obtained using AC impedance electrochemical spectroscopy was between 0.02 and 0.09 S/cm, very similar to the unprocessed Nafion. SCF processing with ethanol as co-solvent reduced the methanol permeability by two orders of magnitude, while the proton conductivity was only reduced by 4%. XRD analysis made to the treated samples exhibited a decreasing pattern in the crystallinity, which affects the transport properties of the membrane. Also, SAXS profiles of the Nafion membranes processed were obtained with the goal of determining changes produced by the SCF processing in the hydrophilic domains of the polymer. With the goal of searching for new alternatives in proton exchange membranes (PEMs) triblock copolymer of poly(styrene-isobutylene-styrene) (SIBS) and poly(styrene-isobutylene-styrene) SEBS were studied. These sulfonated tri-block copolymers had lower methanol permeabilities, but also lower proton

Flagellar membrane fusion and protein exchange in trypanosomes; a new form of cell-cell communication?

PubMed Central

Imhof, Simon; Fragoso, Cristina; Hemphill, Andrew; von Schubert, Conrad; Li, Dong; Legant, Wesley; Betzig, Eric; Roditi, Isabel

2016-01-01

Diverse structures facilitate direct exchange of proteins between cells, including plasmadesmata in plants and tunnelling nanotubes in bacteria and higher eukaryotes.  Here we describe a new mechanism of protein transfer, flagellar membrane fusion, in the unicellular parasite Trypanosoma brucei. When fluorescently tagged trypanosomes were co-cultured, a small proportion of double-positive cells were observed. The formation of double-positive cells was dependent on the presence of extracellular calcium and was enhanced by placing cells in medium supplemented with fresh bovine serum. Time-lapse microscopy revealed that double-positive cells arose by bidirectional protein exchange in the absence of nuclear transfer.  Furthermore, super-resolution microscopy showed that this process occurred in ≤1 minute, the limit of temporal resolution in these experiments. Both cytoplasmic and membrane proteins could be transferred provided they gained access to the flagellum. Intriguingly, a component of the RNAi machinery (Argonaute) was able to move between cells, raising the possibility that small interfering RNAs are transported as cargo. Transmission electron microscopy showed that shared flagella contained two axonemes and two paraflagellar rods bounded by a single membrane. In some cases flagellar fusion was partial and interactions between cells were transient. In other cases fusion occurred along the entire length of the flagellum, was stable for several hours and might be irreversible. Fusion did not appear to be deleterious for cell function: paired cells were motile and could give rise to progeny while fused. The motile flagella of unicellular organisms are related to the sensory cilia of higher eukaryotes, raising the possibility that protein transfer between cells via cilia or flagella occurs more widely in nature. PMID:27239276

Small Business Innovation Research Award Success Story: Proton Energy Systems

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

None

2011-04-01

This success story describes Proton Energy Systems, a small business that designs and manufactures proton exchange membrane (PEM) electrolysis sytems to produce hydrogen from water. The U.S. Department of Energy's Fuel Cell Technologies Program has supported much of Proton's technology development through Small Business Innovation Research (SBIR) Awards and other non-SBIR funding.

Electrolysis of Water in the Secondary School Science Laboratory with Inexpensive Microfluidics

ERIC Educational Resources Information Center

Davis, T. A.; Athey, S. L.; Vandevender, M. L.; Crihfield, C. L.; Kolanko, C. C. E.; Shao, S.; Ellington, M. C. G.; Dicks, J. K.; Carver, J. S.; Holland, L. A.

2015-01-01

This activity allows students to visualize the electrolysis of water in a microfluidic device in under 1 min. Instructional materials are provided to demonstrate how the activity meets West Virginia content standards and objectives. Electrolysis of water is a standard chemistry experiment, but the typical laboratory apparatus (e.g., Hoffman cell)…

Stainless steel anodes for alkaline water electrolysis and methods of making

DOEpatents

Soloveichik, Grigorii Lev

2014-01-21

The corrosion resistance of stainless steel anodes for use in alkaline water electrolysis was increased by immersion of the stainless steel anode into a caustic solution prior to electrolysis. Also disclosed herein are electrolyzers employing the so-treated stainless steel anodes. The pre-treatment process provides a stainless steel anode that has a higher corrosion resistance than an untreated stainless steel anode of the same composition.

Effect of end-group cross-linking on transport properties of sulfonated poly(phenylene sulfide nitrile)s for proton exchange membranes

NASA Astrophysics Data System (ADS)

Kang, Na Rae; Lee, So Young; Shin, Dong Won; Hwang, Doo Sung; Lee, Kang Hyuck; Cho, Doo Hee; Kim, Ji Hoon; Lee, Young Moo

2016-03-01

A series of end-group cross-linked membranes (Az-XESPSN) were prepared by click reaction to investigate the effects of cross-linking on the morphology and proton transport properties of proton exchange membranes. The morphological transformations resulting from thermal annealing and cross-linking were observed by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM). Compared to the non-cross-linked ESPSN membranes, the Az-XESPSN membranes exhibited lower water uptake and improved mechanical and chemical stabilities. In addition, the Az-XESPSN membranes exhibited higher proton conductivities (0.018-0.028 S cm-1) compared to those of the ESPSN membranes (0.0044-0.0053 S cm-1) and Nafion 212 (0.0061 S cm-1), particularly in conditions of elevated temperature (120 °C) and low relative humidity (35%). Such enhancements can be attributed to a synergistic effect of well-defined hydrophilic ionic clusters and triazole groups that function as proton carriers under anhydrous conditions. Furthermore, the Az-XESPSN membranes exhibited significantly enhanced single cell performance and long-term stability compared to those of ESPSN membranes.