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Sample records for membranes water lift

  1. Lifting China's water spell.

    PubMed

    Guan, Dabo; Hubacek, Klaus; Tillotson, Martin; Zhao, Hongyan; Liu, Weidong; Liu, Zhu; Liang, Sai

    2014-10-07

    China is a country with significant but unevenly distributed water resources. The water stressed North stays in contrast to the water abundant and polluted South defining China's current water environment. In this paper we use the latest available data sets and adopt structural decomposition analysis for the years 1992 to 2007 to investigate the driving forces behind the emerging water crisis in China. We employ four water indicators in China, that is, freshwater consumption, discharge of COD (chemical oxygen demand) in effluent water, cumulative COD and dilution water requirements for cumulative pollution, to investigate the driving forces behind the emerging crisis. The paper finds water intensity improvements can effectively offset annual freshwater consumption and COD discharge driven by per capita GDP growth, but that it had failed to eliminate cumulative pollution in water bodies. Between 1992 and 2007, 225 million tones of COD accumulated in Chinese water bodies, which would require 3.2-8.5 trillion m(3) freshwater, depending on the water quality of the recipient water bodies to dilute pollution to a minimum reusable standard. Cumulative water pollution is a key driver to pollution induced water scarcity across China. In addition, urban household consumption, export of goods and services, and infrastructure investment are the main factors contributing to accumulated water pollution since 2000.

  2. A method for impregnating nylon transfer membranes with leucocrystal violet for enhancing and lifting bloody impressions.

    PubMed

    Michaud, Amy L; Brun-Conti, Leanora

    2004-05-01

    The objective of this research project was to demonstrate a quick and easy method for impregnating nylon transfer membranes with leucocrystal violet (LCV) for the purpose of lifting and enhancing impressions made in blood. A stamp that would simulate fine detail found in fingerprints or footwear was used to create impressions on a variety of substrates. Four different LCV formulations were tested to determine the effectiveness of the prepared membranes in lifting and enhancing the impressions. Further investigation involved the feasibility of using the LCV membranes in the field by studying the shelf life and storage of the impregnated membranes and the longevity of the lifted impressions. One of the formations studied demonstrated superior lifting and enhancing capabilities, as well as a prolonged shelf life and a resilience of the lifted impressions, thus proving LCV to be an extremely valuable technique.

  3. Water vapor diffusion membranes

    NASA Technical Reports Server (NTRS)

    Holland, F. F., Jr.; Smith, J. K.

    1974-01-01

    The program is reported, which was designed to define the membrane technology of the vapor diffusion water recovery process and to test this technology using commercially available or experimental membranes. One membrane was selected, on the basis of the defined technology, and was subjected to a 30-day demonstration trial.

  4. Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; Almlie, Jay C.

    2010-01-01

    A water membrane evaporator (WME) has been conceived and tested as an alternative to the contamination-sensitive and corrosion-prone evaporators currently used for dissipating heat from space vehicles. The WME consists mainly of the following components: An outer stainless-steel screen that provides structural support for the components mentioned next; Inside and in contact with the stainless-steel screen, a hydrophobic membrane that is permeable to water vapor; Inside and in contact with the hydrophobic membrane, a hydrophilic membrane that transports the liquid feedwater to the inner surface of the hydrophobic membrane; Inside and in contact with the hydrophilic membrane, an annular array of tubes through which flows the spacecraft coolant carrying the heat to be dissipated; and An inner exclusion tube that limits the volume of feedwater in the WME. In operation, a pressurized feedwater reservoir is connected to the volume between the exclusion tube and the coolant tubes. Feedwater fills the volume, saturates the hydrophilic membrane, and is retained by the hydrophobic membrane. The outside of the WME is exposed to space vacuum. Heat from the spacecraft coolant is conducted through the tube walls and the water-saturated hydrophilic membrane to the liquid/vapor interface at the hydrophobic membrane, causing water to evaporate to space. Makeup water flows into the hydrophilic membrane through gaps between the coolant tubes.

  5. Sheet Membrane Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  6. Water vapor diffusion membrane development

    NASA Technical Reports Server (NTRS)

    Tan, M. K.

    1976-01-01

    A total of 18 different membranes were procured, characterized, and tested in a modified bench-scale vapor diffusion water reclamation unit. Four membranes were selected for further studies involving membrane fouling. Emphasis was placed on the problem of flux decline due to membrane fouling. This is discussed in greater details under "Summary and Discussion on Membrane Fouling Studies" presented in pages 47-51. The system was also investigated for low temperature application on wash-water where the permeated water is not recovered but vented into space vacuum.

  7. Advanced underwater lift device

    NASA Technical Reports Server (NTRS)

    Flanagan, David T.; Hopkins, Robert C.

    1993-01-01

    Flexible underwater lift devices ('lift bags') are used in underwater operations to provide buoyancy to submerged objects. Commercially available designs are heavy, bulky, and awkward to handle, and thus are limited in size and useful lifting capacity. An underwater lift device having less than 20 percent of the bulk and less than 10 percent of the weight of commercially available models was developed. The design features a dual membrane envelope, a nearly homogeneous envelope membrane stress distribution, and a minimum surface-to-volume ratio. A proof-of-concept model of 50 kg capacity was built and tested. Originally designed to provide buoyancy to mock-ups submerged in NASA's weightlessness simulators, the device may have application to water-landed spacecraft which must deploy flotation upon impact, and where launch weight and volume penalties are significant. The device may also be useful for the automated recovery of ocean floor probes or in marine salvage applications.

  8. New fire-fighting water bucket is lifted from water for a demonstration

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A NASA helicopter lifts a high-impact-resistant flexible plastic bucket filled with water. The container will be used for fire protection on property and buildings at Kennedy Space Center.. Known as the 'Bambi' bucket, it will also support the Fish and Wildlife Service for controlled burns plus any wild fires in the area.

  9. Study on dynamic characteristics of coupled model for deep-water lifting system

    NASA Astrophysics Data System (ADS)

    Wu, Yunxia; Lu, Jianhui; Zhang, Chunlei

    2016-10-01

    The underwater installation of marine equipment in deep-water development requires safe lifting and accurate positioning. The heave compensation system is an important technology to ensure normal operation and improve work accuracy. To provide a theoretical basis for the heave compensation system, in this paper, the continuous modeling method is employed to build up a coupled model of deep-water lifting systems in vertical direction. The response characteristics of dynamic movement are investigated. The simulation results show that the resonance problem appears in the process of the whole releasing load, the lifting system generates resonance and the displacement response of the lifting load is maximal when the sinking depth is about 2000 m. This paper also analyzes the main influencing factors on the dynamic response of load including cable stiffness, damping coefficient of the lifting system, mass and added mass of lifting load, among which cable stiffness and damping coefficient of the lifting system have the greatest influence on dynamic response of lifting load when installation load is determined. So the vertical dynamic movement response of the load is reduced by installing a damper on the lifting cable and selecting the appropriate cable stiffness.

  10. An assessment of diurnal water uptake in a mesic prairie: evidence for hydraulic lift?

    PubMed

    O'Keefe, Kimberly; Nippert, Jesse B

    2017-04-01

    Hydraulic lift, the passive movement of water through plant roots from wet to dry soil, is an important ecohydrological process in a wide range of water-limited ecosystems. This phenomenon may also alter plant functioning, growth, and survival in mesic grasslands, where soil moisture is spatially and temporally variable. Here, we monitored diurnal changes in the isotopic signature of soil and plant xylem water to assess (1) whether hydraulic lift occurs in woody and herbaceous tallgrass prairie species (Rhus glabra, Amorpha canescens, Vernonia baldwinii, and Andropogon gerardii), (2) if nocturnal transpiration or grazing by large ungulates limits hydraulic lift, and (3) if a dominant grass, A. gerardii, utilizes water lifted by other tallgrass prairie species. Broadly, the results shown here suggest that hydraulic lift does not appear to be widespread or common in this system, but isolated instances suggest that this process does occur within tallgrass prairie. The isolated instance of hydraulic lift did not vary by grazing treatment, nor did they result in facilitation for neighboring grasses. We suggest that the topographic complexity of this tallgrass prairie and the high rates of nocturnal transpiration observed in this study likely limit the frequency and occurrence of hydraulic lift. These results suggest that hydraulic lift can be a patchy process, particularly in heterogeneous landscapes.

  11. Membrane bioreactors for water reclamation.

    PubMed

    Tao, G; Kekre, K; Wei, Z; Lee, T C; Viswanath, B; Seah, H

    2005-01-01

    Singapore has been using dual membrane technology (MF/UF RO) to produce high-grade water (NEWater) from secondary treated sewage. Membrane bioreactor (MBR) has very high potential and will lead to the further improvement of the productivity and quality of high-grade water. This study was focused on the technical feasibility of MBR system for water reclamation in Singapore, making a comparison between various membrane systems available and to get operational experience in terms of membrane cleaning and other issues. Three MBR plants were built at Bedok Water Reclamation Plant with a design flow of 300 m3/day each. They were commissioned in March 2003. Three different types of submerged membranes were tested. They are Membrane A, plate sheet membrane with pore size of 0.4 microm; Membrane B, hollow fibre membrane with pore size of 0.4 microm; and Membrane C, hollow fibre membrane with pore size of 0.035 microm. The permeate quality of all the three MBR Systems were found equivalent to or better than that of the conventional tertiary treatment by ultrafiltration. MBR permeate TOC was about 2 mg/l lower than UF permeate TOC. GC-MS, GC-ECD and HPLC scan results show that trace organic contaminants in MBR permeate and UF permeate were in the same range. MBR power consumption can be less than 1 kwh/m3. Gel layer or dynamic membrane generated on the submerged membrane surface played an important role for the lower MBR permeate TOC than the supernatant TOC in the membrane tank. Intensive chemical cleaning can temporarily remove this layer. During normal operation conditions, the formation of dynamic membrane may need one day to obtain the steady low TOC levels in MBR permeate.

  12. New fire-fighting water bucket is lifted by helicopter

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A NASA helicopter lifts a high-impact-resistant flexible plastic bucket that will be used for fire protection on property and buildings at Kennedy Space Center. Known as the 'Bambi' bucket, the 324-gallon container will also support the Fish and Wildlife Service for controlled burns plus any wild fires in the area.

  13. Water vapor diffusion membranes, 2

    NASA Technical Reports Server (NTRS)

    Holland, F. F.; Klein, E.; Smith, J. K.; Eyer, C.

    1976-01-01

    Transport mechanisms were investigated for the three different types of water vapor diffusion membranes. Membranes representing porous wetting and porous nonwetting structures as well as dense diffusive membrane structures were investigated for water permeation rate as a function of: (1) temperature, (2) solids composition in solution, and (3) such hydrodynamic parameters as sweep gas flow rate, solution flow rate and cell geometry. These properties were measured using nitrogen sweep gas to collect the effluent. In addition, the chemical stability to chromic acid-stabilized urine was measured for several of each type of membrane. A technology based on the mechanism of vapor transport was developed, whereby the vapor diffusion rates and relative susceptibility of membranes to fouling and failure could be projected for long-term vapor recovery trials using natural chromic acid-stabilized urine.

  14. Water vapor diffusion membrane development

    NASA Technical Reports Server (NTRS)

    Tan, M. K.

    1977-01-01

    An application of the water vapor diffusion technique is examined whereby the permeated water vapor is vented to space vacuum to alleviate on-board waste storage and provide supplemental cooling. The work reported herein deals primarily with the vapor diffusion-heat rejection (VD-HR) as it applies to the Space Shuttle. A stack configuration was selected, designed and fabricated. An asymmetric cellulose acetate membrane, used in reverse osmosis application was selected and a special spacer was designed to enhance mixing and promote mass transfer. A skid-mount unit was assembled from components used in the bench unit although no attempt was made to render it flight-suitable. The operating conditions of the VD-HR were examined and defined and a 60-day continuous test was carried out. The membranes performed very well throughout the test; no membrane rupture and no unusual flux decay was observed. In addition, a tentative design for a flight-suitable VD-HR unit was made.

  15. Contribution of hydraulically lifted deep moisture to the water budget in a Southern California mixed forest

    NASA Astrophysics Data System (ADS)

    Kitajima, Kuni; Allen, Michael F.; Goulden, Michael L.

    2013-12-01

    and shrubs growing in California's mountains rely on deep roots to survive the hot and dry Mediterranean climate summer. The shallow montane soil cannot hold enough water to support summer transpiration, and plants must access deeper moisture from the weathered bedrock. We used the HYDRUS-1D model to simulate the moisture flux through the soil-plant continuum in Southern California's San Jacinto Mountains. The mechanisms facilitating deep water access are poorly understood, and it is possible that either or both hydraulic lift and capillary rise contribute to the survival and activity of trees and soil microorganisms. We modified HYDRUS to incorporate hydraulic lift and drove it with meteorological and physiological data. The modeled quantity of water lifted hydraulically ranged from near zero during the wet months to ~28 mm month-1 in midsummer. Likewise, modeled capillary rise was negligible during the winter and averaged ~15 mm month-1 during June through November. Both mechanisms provided water to support evapotranspiration during the dry months. Isotopic measurements of xylem water for eight shrub and tree species confirmed the importance of a deep source of water. Conventional and automated minirhizotron observations showed that fine-root and rhizomorph biomass remained relatively constant year-round, while mycorrhizal hyphae biomass varied markedly, peaking in the wet season and declining by ~70% in the dry season. Model results predict that hydraulic lift and capillary rise play key roles in Southern California's mountains: they support evapotranspiration and photosynthesis during the summer drought; they contribute to the year-round survival of fine roots and soil microorganisms.

  16. Ionomer-Membrane Water Processing Apparatus

    NASA Technical Reports Server (NTRS)

    MacCallum, Taber K. (Inventor); Kelsey, Laura (Inventor)

    2016-01-01

    This disclosure provides water processing apparatuses, systems, and methods for recovering water from wastewater such as urine. The water processing apparatuses, systems, and methods can utilize membrane technology for extracting purified water in a single step. A containment unit can include an ionomer membrane, such as Nafion(Registered Trademark), over a hydrophobic microporous membrane, such as polytetrafluoroethylene (PTFE). The containment unit can be filled with wastewater, and the hydrophobic microporous membrane can be impermeable to liquids and solids of the wastewater but permeable to gases and vapors of the wastewater, and the ionomer membrane can be permeable to water vapor but impermeable to one or more contaminants of the gases and vapors. The containment unit can be exposed to a dry purge gas to maintain a water vapor partial pressure differential to drive permeation of the water vapor, and the water vapor can be collected and processed into potable water.

  17. Ionomer-Membrane Water Processing Methods

    NASA Technical Reports Server (NTRS)

    MacCallum, Taber K. (Inventor); Kelsey, Laura (Inventor)

    2016-01-01

    This disclosure provides water processing apparatuses, systems, and methods for recovering water from wastewater such as urine. The water processing apparatuses, systems, and methods can utilize membrane technology for extracting purified water in a single step. A containment unit can include an ionomer membrane, such as Nafion(TradeMark) over a hydrophobic microporous membrane, such as polytetrafluoroethylene (PTFE). The containment unit can be filled with wastewater, and the hydrophobic microporous membrane can be impermeable to liquids and solids of the wastewater but permeable to gases and vapors of the wastewater, and the ionomer membrane can be permeable to water vapor but impermeable to one or more contaminants of the gases and vapors. The containment unit can be exposed to a dry purge gas to maintain a water vapor partial pressure differential to drive permeation of the water vapor, and the water vapor can be collected and processed into potable water.

  18. Use of nonwettable membranes for water transfer

    NASA Technical Reports Server (NTRS)

    Hausch, H. G.

    1970-01-01

    Transfer of water through nonwettable vinyl fluoride membranes has two unique features - /1/ very low water transfer rates can be held constant by holding temperature and solute concentrations constant, /2/ the pressure gradient against which water is transported is limited only by solution breakthrough or membrane strength.

  19. The Properties of Water in Polymeric Membranes.

    DTIC Science & Technology

    cellulose acetate (CA) membranes have been investigated by magnetic resonance techniques. The data suggest existence in the CA membrane, of two ’types’ of water: a small fraction of highly immobilized ’bound’ water and the remaining large fraction of ’free’ water. The NMR spectra of water adsorbed at various relative humidities on various cellulose ester membranes also have been studied. Membranes of cellulose acetate , triacetate and acetate-butyrate were investigated. The data suggest that the dependence of the

  20. Efflux of hydraulically lifted water from mycorrhizal fungal hyphae during imposed drought.

    PubMed

    Egerton-Warburton, Louise M; Querejeta, José Ignacio; Allen, Michael F

    2008-01-01

    Apart from improving plant and soil water status during drought, it has been suggested that hydraulic lift (HL) could enhance plant nutrient capture through the flow of mineral nutrients directly from the soil to plant roots, or by maintaining the functioning of mycorrhizal fungi. We evaluated the extent to which the diel cycle of water availability created by HL covaries with the efflux of HL water from the tips of extramatrical (external) mycorrhizal hyphae, and the possible effects on biogeochemical processes. Phenotypic mycorrhizal fungal variables, such as total and live hyphal lengths, were positively correlated with HL efflux from hyphae, soil water potential (dawn), and plant response variables (foliar (15)N). The efflux of HL water from hyphae was also correlated with bacterial abundance and soil enzyme activity (P), and the moistening of soil organic matter. Such findings indicate that the efflux of HL water from the external mycorrhizal mycelia may be a complementary explanation for plant nutrient acquisition and survival during drought.

  1. A nanoporous silicon nitride membrane using a two-step lift-off pattern transfer with thermal nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Nabar, Bhargav P.; Çelik-Butler, Zeynep; Dennis, Brian H.; Billo, Richard E.

    2012-04-01

    Nanoimprint lithography is emerging as a viable contender for fabrication of large-scale arrays of 5-500 nm features. A fabrication process for the realization of thin nanoporous membranes using thermal nanoimprint lithography is presented. Suspended silicon nitride membranes were fabricated by low-pressure chemical vapor deposition (LPCVD) in conjunction with a potassium hydroxide-based bulk micromachining process. Nanoscale features were imprinted into a commercially available thermoplastic polymer resist using a prefabricated silicon mold. The pattern was reversed and transferred to a thin aluminum oxide layer by means of a novel two-stage lift-off technique. The patterned aluminum oxide was used as an etch mask in a CHF3/He-based reactive ion etch process to transfer the pattern to silicon nitride. Highly directional etch profiles with near vertical sidewalls and excellent Si3N4/Al2O3 etch selectivity were observed. One micrometer thick porous membranes with varying dimensions of 250 × 250 µm2 to 450 × 450 µm2 and a pore diameter of 400 nm have been engineered and evaluated. Results indicate that the membranes have consistent nanopore dimensions and precisely defined porosity, which makes them ideal as gas exchange interfaces in blood oxygenation systems as well as other applications such as dialysis.

  2. Paramagnetic-based NMR restraints lift residual dipolar coupling degeneracy in multidomain detergent-solubilized membrane proteins.

    PubMed

    Shi, Lei; Traaseth, Nathaniel J; Verardi, Raffaello; Gustavsson, Martin; Gao, Jiali; Veglia, Gianluigi

    2011-02-23

    Residual dipolar couplings (RDCs) are widely used as orientation-dependent NMR restraints to improve the resolution of the NMR conformational ensemble of biomacromolecules and define the relative orientation of multidomain proteins and protein complexes. However, the interpretation of RDCs is complicated by the intrinsic degeneracy of analytical solutions and protein dynamics that lead to ill-defined orientations of the structural domains (ghost orientations). Here, we illustrate how restraints from paramagnetic relaxation enhancement (PRE) experiments lift the orientational ambiguity of multidomain membrane proteins solubilized in detergent micelles. We tested this approach on monomeric phospholamban (PLN), a 52-residue membrane protein, which is composed of two helical domains connected by a flexible loop. We show that the combination of classical solution NMR restraints (NOEs and dihedral angles) with RDC and PRE constraints resolves topological ambiguities, improving the convergence of the PLN structural ensemble and giving the depth of insertion of the protein within the micelle. The combination of RDCs with PREs will be necessary for improving the accuracy and precision of membrane protein conformational ensembles, where three-dimensional structures are dictated by interactions with the membrane-mimicking environment rather than compact tertiary folds common in globular proteins.

  3. Sheet Membrane Spacesuit Water Membrane Evaporator Thermal Test

    NASA Technical Reports Server (NTRS)

    Trevino, Luis A.; Bue, Grant C.

    2009-01-01

    For future lunar extravehicular activities (EVA), one method under consideration for rejecting crew and electronics heat involves evaporating water through a hydrophobic, porous Teflon(Registered Trademark) membrane. A Spacesuit Water Membrane Evaporator (SWME) prototype using this membrane was successfully tested by Ungar and Thomas (2001) with predicted performance matching test data well. The above referenced work laid the foundation for the design of a compact sheet membrane SWME development unit for use in the Constellation System Spacesuit Element Portable Life Support System (Vogel and et. al., ICES 2008). Major design objectives included minimizing mass, volume, and manufacturing complexity while rejecting a minimum of 810 watts of heat from water flowing through the SWME at 91 kg/hr with an inlet temperature of 291K. The design meeting these objectives consisted of three concentric cylindrical water channels interlaced with four water vapor channels. Two units were manufactured for the purpose of investigating manufacturing techniques and performing thermal testing. The extensive thermal test measured SWME heat rejection as a function of water inlet temperatures, water flow-rates, water absolute pressures, water impurities, and water vapor back-pressures. This paper presents the test results and subsequent analysis, which includes a comparison of SWME heat rejection measurements to pretest predictions. In addition, test measurements were taken such that an analysis of the commercial-off-the-shelf vapor pressure control valve could be performed.

  4. The Properties of Water in Polymeric Membranes.

    DTIC Science & Technology

    The relative amounts of freezing and non-freezing water in various water-wet cellulose acetate (CA) membranes have been determined by NMR techniques...by reverse osmosis is compared to that of the commonly used cellulose acetate .

  5. Water treatment by membrane technology

    NASA Astrophysics Data System (ADS)

    Balint, Agneta M.; Balint, Stefan; Viskolcz, Béla

    2012-08-01

    This paper is a short presentation of the membrane system. For the case when the pressure differential is at the origin of the transport through the membrane, a mathematical model is proposed. In the framework of the model the membrane performance (flux and retention) can be computed. Numerical illustration is given.

  6. Surface Modification of Water Purification Membranes.

    PubMed

    Miller, Daniel J; Dreyer, Daniel R; Bielawski, Christopher W; Paul, Donald R; Freeman, Benny D

    2017-04-18

    Polymeric membranes are an energy-efficient means of purifying water, but they suffer from fouling during filtration. Modification of the membrane surface is one route to mitigating membrane fouling, as it helps to maintain high levels of water productivity. Here, a series of common techniques for modification of the membrane surface are reviewed, including surface coating, grafting, and various treatment techniques such as chemical treatment, UV irradiation, and plasma treatment. Historical background on membrane development and surface modification is also provided. Finally, polydopamine, an emerging material that can be easily deposited onto a wide variety of substrates, is discussed within the context of membrane modification. A brief summary of the chemistry of polydopamine, particularly as it may pertain to membrane development, is also described.

  7. Energetics of water permeation through fullerene membrane

    PubMed Central

    Isobe, Hiroyuki; Homma, Tatsuya; Nakamura, Eiichi

    2007-01-01

    Lipid bilayer membranes are important as fundamental structures in biology and possess characteristic water-permeability, stability, and mechanical properties. Water permeation through a lipid bilayer membrane occurs readily, and more readily at higher temperature, which is largely due to an enthalpy cost of the liquid-to-gas phase transition of water. A fullerene bilayer membrane formed by dissolution of a water-soluble fullerene, Ph5C60K, has now been shown to possess properties entirely different from those of the lipid membranes. The fullerene membrane is several orders of magnitude less permeable to water than a lipid membrane, and the permeability decreases at higher temperature. Water permeation is burdened by a very large entropy loss and may be favored slightly by an enthalpy gain, which is contrary to the energetics observed for the lipid membrane. We ascribe this energetics to favorable interactions of water molecules to the surface of the fullerene molecules as they pass through the clefts of the rigid fullerene bilayer. The findings provide possibilities of membrane design in science and technology. PMID:17846427

  8. Environmental Assessment Relocation of the Aircraft Oil/Water Separator and Lift Station

    DTIC Science & Technology

    2004-06-01

    CES/CEV),600 Chevron Ave,Dover AFB,DE,19902 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10 ...Purpose of Contact: ERP information 10 8.0 REFERENCES "Dover Air Force Base, Cultural Resources Management Plan", October 2000 "Biological and...HEADQUARTERS 436TH AIRLIFf WING (AMC) MEMORANDUM FOR 436 MSG/CC FROM: 436 AW/JA SUBJECT: FONSI for Relocation of Oil/Water Separator and Lift Station 10 May

  9. Protein Solvation in Membranes and at Water-Membrane Interfaces

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Chipot, Christophe; Wilson, Michael A.

    2002-01-01

    Different salvation properties of water and membranes mediate a host of biologically important processes, such as folding, insertion into a lipid bilayer, associations and functions of membrane proteins. These processes will be discussed in several examples involving synthetic and natural peptides. In particular, a mechanism by which a helical peptide becomes inserted into a model membrane will be described. Further, the molecular mechanism of recognition and association of protein helical segments in membranes will be discussed. These processes are crucial for proper functioning of a cell. A membrane-spanning domain of glycophorin A, which exists as a helical dimer, serves as the model system. For this system, the free energy of dissociation of the helices is being determined for both the wild type and a mutant, in which dimerization is disrupted.

  10. Coupling Mars' Dust and Water Cycles: Effects on Dust Lifting Vigor, Spatial Extent and Seasonality

    NASA Technical Reports Server (NTRS)

    Kahre, M. A.; Hollingsworth, J. L.; Haberle, R. M.; Montmessin, F.

    2012-01-01

    The dust cycle is an important component of Mars' current climate system. Airborne dust affects the radiative balance of the atmosphere, thus greatly influencing the thermal and dynamical state of the atmosphere. Dust raising events on Mars occur at spatial scales ranging from meters to planet-wide. Although the occurrence and season of large regional and global dust storms are highly variable from one year to the next, there are many features of the dust cycle that occur year after year. Generally, a low-level dust haze is maintained during northern spring and summer, while elevated levels of atmospheric dust occur during northern autumn and winter. During years without global-scale dust storms, two peaks in total dust loading were observed by MGS/TES: one peak occurred before northern winter solstice at Ls 200-240, and one peak occurred after northern winter solstice at L(sub s) 305-340. These maxima in dust loading are thought to be associated with transient eddy activity in the northern hemisphere, which has been observed to maximize pre- and post-solstice. Interactive dust cycle studies with Mars General Circulation Models (MGCMs) have included the lifting, transport, and sedimentation of radiatively active dust. Although the predicted global dust loadings from these simulations capture some aspects of the observed dust cycle, there are marked differences between the simulated and observed dust cycles. Most notably, the maximum dust loading is robustly predicted by models to occur near northern winter solstice and is due to dust lifting associated with down slope flows on the flanks of the Hellas basin. Thus far, models have had difficulty simulating the observed pre- and post- solstice peaks in dust loading. Interactive dust cycle studies typically have not included the formation of water ice clouds or their radiative effects. Water ice clouds can influence the dust cycle by scavenging dust from atmosphere and by interacting with solar and infrared radiation

  11. Microbiological safety of household membrane water filter.

    PubMed

    Zhang, Yongli; Wang, Qing; Lou, Wei; Wang, Yuxin; Zhu, Xuan

    2013-04-01

    Waterborne pathogens outbreaks are major reasons of diarrhea disease worldwide. Detecting and monitoring emerging waterborne pathogens (EWPs) is important for drinking water microbiological safety. The microbiological safety of household water hollow fiber membrane filter which is the end of drinking water treatment process was studied with heterotrophic plate count (HPC) and real-time PCR method. The effect of the flow rate, idle time and washing fashion were investigated. Among the selected filters from three manufacturers, only the PVDF membrane water filter (Brand B) could achieve a good water purification criteria. Brand A was found a certain degree of EWPs in its effluent. The lowest bacteria-removing efficiency of the PVC membrane water filter was found Brand C. Our study showed that the microorganisms could reach up to 10(6) CFU ml(-1) and the 16s rDNA could reach up to 10(6) copies ml(-1) in the initial filtrate of Brand C. More species and amounts of EWPs were detected in the washing water. These results suggested that the popular household membrane filters might cause microbiological risks at certain circumstances such as the shock load of EWPs and leakage of the membranes in the case of abnormal source water or poor membrane filter quality.

  12. Common mycorrhizal networks provide a potential pathway for the transfer of hydraulically lifted water between plants.

    PubMed

    Egerton-Warburton, Louise M; Querejeta, José Ignacio; Allen, Michael F

    2007-01-01

    Plant roots may be linked by shared or common mycorrhizal networks (CMNs) that constitute pathways for the transfer of resources among plants. The potential for water transfer by such networks was examined by manipulating CMNs independently of plant roots in order to isolate the role(s) of ectomycorrhizal (EM) and arbuscular mycorrhizal fungal (AMF) networks in the plant water balance during drought (soil water potential -5.9 MPa). Fluorescent tracer dyes and deuterium-enriched water were used to follow the pathways of water transfer from coastal live oak seedlings (Quercus agrifolia Nee; colonized by EM and AMF) conducting hydraulic lift (HL) into the roots of water-stressed seedlings connected only by EM (Q. agrifolia) or AMF networks (Q. agrifolia, Eriogonum fasciculatum Benth., Salvia mellifera Greene, Keckiella antirrhinoides Benth). When connected to donor plants by hyphal linkages, deuterium was detected in the transpiration flux of receiver oak plants, and dye-labelled extraradical hyphae, rhizomorphs, mantles, and Hartig nets were observed in receiver EM oak roots, and in AMF hyphae of Salvia. Hyphal labelling was scarce in Eriogonum and Keckiella since these species are less dependent on AMF. The observed patterns of dye distribution also indicated that only a small percentage of mycorrhizal roots and extraradical hyphae were involved with water transfer among plants. Our results suggest that the movement of water by CMNs is potentially important to plant survival during drought, and that the functional ecophysiological traits of individual mycorrhizal fungi may be a component of this mechanism.

  13. Efflux of hydraulically lifted water from mycorrhizal fungal hyphae during imposed drought

    PubMed Central

    Querejeta, José Ignacio; Allen, Michael F

    2008-01-01

    Apart from improving plant and soil water status during drought, it has been suggested that hydraulic lift (HL) could enhance plant nutrient capture through the flow of mineral nutrients directly from the soil to plant roots, or by maintaining the functioning of mycorrhizal fungi. We evaluated the extent to which the diel cycle of water availability created by HL covaries with the efflux of HL water from the tips of extramatrical (external) mycorrhizal hyphae, and the possible effects on biogeochemical processes. Phenotypic mycorrhizal fungal variables, such as total and live hyphal lengths, were positively correlated with HL efflux from hyphae, soil water potential (dawn), and plant response variables (foliar 15N). The efflux of HL water from hyphae was also correlated with bacterial abundance and soil enzyme activity (P), and the moistening of soil organic matter. Such findings indicate that the efflux of HL water from the external mycorrhizal mycelia may be a complementary explanation for plant nutrient acquisition and survival during drought. PMID:19704776

  14. Biological Principles and Physiology of Bone Regeneration under the Schneiderian Membrane after Sinus Lift Surgery: A Radiological Study in 14 Patients Treated with the Transcrestal Hydrodynamic Ultrasonic Cavitational Sinus Lift (Intralift)

    PubMed Central

    Troedhan, A.; Kurrek, A.; Wainwright, M.

    2012-01-01

    Introduction. Sinus lift procedures are a commonly accepted method of bone augmentation in the lateral maxilla with clinically good results. Nevertheless the role of the Schneiderian membrane in the bone-reformation process is discussed controversially. Aim of this study was to prove the key role of the sinus membrane in bone reformation in vivo. Material and Methods. 14 patients were treated with the minimal invasive tHUCSL-Intralift, and 2 ccm collagenous sponges were inserted subantrally and the calcification process followed up with CBCT scans 4 and 7 months after surgery. Results. An even and circular centripetal calcification under the sinus membrane and the antral floor was detected 4 months after surgery covering 30% of the entire augmentation width/height/depth at each wall. The calcification process was completed in the entire augmentation volume after 7 months. A loss of approximately 13% of absolute augmentation height was detected between the 4th and 7th month. Discussion. The results of this paper prove the key role of the sinus membrane as the main carrier of bone reformation after sinus lift procedures as multiple experimental studies suggested. Thus the importance of minimal invasive and rupture free sinuslift procedures is underlined and does not depend on the type of grafting material used. PMID:22754571

  15. Understanding transport in model water desalination membranes

    NASA Astrophysics Data System (ADS)

    Chan, Edwin

    Polyamide based thin film composites represent the the state-of-the-art nanofiltration and reverse osmosis membranes used in water desalination. The performance of these membranes is enabled by the ultrathin (~100 nm) crosslinked polyamide film in facilitating the selective transport of water over salt ions. While these materials have been refined over the last several decades, understanding the relationships between polyamide structure and membrane performance remains a challenge because of the complex and heterogeneous nature of the polyamide film. In this contribution, we present our approach to addressing this challenge by studying the transport properties of model polyamide membranes synthesized via molecular layer-by-layer (mLbL) assembly. First, we demonstrate that mLbL can successfully construct polyamide membranes with well-defined nanoscale thickness and roughness using a variety of monomer formulations. Next, we present measurement tools for characterizing the network structure and transport of these model polyamide membranes. Specifically, we used X-ray and neutron scattering techniques to characterize their structure as well as a recently-developed indentation based poromechanics approach to extrapolate their water diffusion coefficient. Finally, we illustrate how these measurements can provide insight into the original problem by linking the key polyamide network properties, i.e. water-polyamide interaction parameter and characteristic network mesh size, to the membrane performance.

  16. Multilayer Nanoporous Graphene Membranes for Water Desalination.

    PubMed

    Cohen-Tanugi, David; Lin, Li-Chiang; Grossman, Jeffrey C

    2016-02-10

    While single-layer nanoporous graphene (NPG) has shown promise as a reverse osmosis (RO) desalination membrane, multilayer graphene membranes can be synthesized more economically than the single-layer material. In this work, we build upon the knowledge gained to date toward single-layer graphene to explore how multilayer NPG might serve as a RO membrane in water desalination using classical molecular dynamic simulations. We show that, while multilayer NPG exhibits similarly promising desalination properties to single-layer membranes, their separation performance can be designed by manipulating various configurational variables in the multilayer case. This work establishes an atomic-level understanding of the effects of additional NPG layers, layer separation, and pore alignment on desalination performance, providing useful guidelines for the design of multilayer NPG membranes.

  17. Spontaneous release of epiretinal membrane in a young weight-lifting athlete by presumed central rupture and centrifugal pull

    PubMed Central

    Mansour, Ahmad M; Mansour, Hana A; Arevalo, J Fernando

    2014-01-01

    This patient presented for surgery at the age of 32 years, 14 months after his initial complaint of metamorphopsia and visual loss in the right eye. Past tests demonstrated a whitish epiretinal membrane (ERM) with translucent stress lines over a thickened macula. Visual acuity was found on last presentation to be normal with minimal alteration on Amsler grid testing. A torn ERM was found in the center with left-over ERM temporally and rolled-over ERM nasally at the site of the epicenter with no posterior vitreous detachment. Visual recovery occurred gradually over several days 2 months prior to presentation apparently following heavy weight-lifting with a sensation of severe eye pressure. Sequential funduscopy and optical coherence tomography scans demonstrated the peeling of an ERM accompanied by normalization of foveal thickness. Valsalva maneuver had put excessive tension on ERM which tore in its center at the weakest line with gradual contraction of the ERM away from the fovea towards the peripapillary area. This is a new mechanism of self-separation of ERM induced by Valsalva. ERM in young subjects is subject to rupture and subsequent separation by tangential traction. There are three mechanisms for spontaneous separation of ERM: 1) posterior vitreous detachment with pulling of ERM by detaching vitreous (most common in adults); 2) the contracting forces of the immature ERM become stronger than its adhesions to the retina resulting in slow tangential traction on the edges of the ERM and gradual separation from the edges towards the center (remodeling common in youngsters); and 3) acute tearing of ERM at its weakest central point and retraction of part of the membrane towards the epicenter (current case report). PMID:25484573

  18. Shrinking water's no man's land by lifting its low-temperature boundary

    NASA Astrophysics Data System (ADS)

    Seidl, Markus; Fayter, Alice; Stern, Josef N.; Zifferer, Gerhard; Loerting, Thomas

    2015-04-01

    Investigation of the properties and phase behavior of noncrystalline water is hampered by rapid crystallization in the so-called "no man's land." We here show that it is possible to shrink the no man's land by lifting its low-temperature boundary, i.e., the pressure-dependent crystallization temperature Tx(p ) . In particular, we investigate two types of high-density amorphous ice (HDA) in the pressure range of 0.10 -0.50 GPa and show that the commonly studied unannealed state, uHDA, is up to 11 K less stable against crystallization than a pressure-annealed state called eHDA. We interpret this finding based on our previously established microscopic picture of uHDA and eHDA, respectively [M. Seidl et al., Phys. Rev. B 88, 174105 (2013), 10.1103/PhysRevB.88.174105]. In this picture the glassy uHDA matrix contains ice Ih-like nanocrystals, which simply grow upon heating uHDA at pressures ≤0.20 GPa . By contrast, they experience a polymorphic phase transition followed by subsequent crystal growth at higher pressures. In comparison, upon heating purely glassy eHDA, ice nuclei of a critical size have to form in the first step of crystallization, resulting in a lifted Tx(p ) . Accordingly, utilizing eHDA enables the study of amorphous ice at significantly higher temperatures at which we regard it to be in the ultraviscous liquid state. This will boost experiments aiming at investigating the proposed liquid-liquid phase transition.

  19. Separation of tritiated water from water using composite membranes

    SciTech Connect

    Duncan, J.; Nelson, D.

    1996-10-01

    Polymeric composite membranes are being developed to remove tritium from contaminated water at DOE sites. Industrial membrane systems are being developed that have proven to be energy efficient, and membrane technologies such as reverse-osmosis have been well developed for desalination and other industrial/municipal applications. Aromatic polyphosphazene membranes are being investigated because they have excellent radiological, thermal, and chemical stability. The FY 1996 effort is directed toward delineating a potential mechanism, providing a statistical approach to data acquisition, refining a mass balance, and designing a staged array module.

  20. SEPARATION OF TRITIATED WATER FROM WATER USING COMPOSITE MEMBRANES

    SciTech Connect

    DUNCAN JB; NELSON DA

    1995-12-18

    The work in this task involves the use of composite membranes to remove tritium from contaminated water at DOE sites. Experience with membrane systems in industry indicates that they are inherently energy efficient. Furthermore, membrane technologies such as reverse-osmosis have been well developed for desalination and other industrial/municipal applications. Aromatic polyphosphazenes were chosen as the polymeric material for the membranes being investigated because they have excellent radiological, thermal, and chemical stability. The FY-96 effort is directed toward empirical delineation of a potential mechanism, providing a statistical approach to data acquisition, further mass balance determination, and a preliminary design for the module staged array.

  1. Calculation of water drop trajectories to and about arbitrary three-dimensional lifting and nonlifting bodies in potential airflow

    NASA Technical Reports Server (NTRS)

    Norment, H. G.

    1985-01-01

    Subsonic, external flow about nonlifting bodies, lifting bodies or combinations of lifting and nonlifting bodies is calculated by a modified version of the Hess lifting code. Trajectory calculations can be performed for any atmospheric conditions and for all water drop sizes, from the smallest cloud droplet to large raindrops. Experimental water drop drag relations are used in the water drop equations of motion and effects of gravity settling are included. Inlet flow can be accommodated, and high Mach number compressibility effects are corrected for approximately. Seven codes are described: (1) a code used to debug and plot body surface description data; (2) a code that processes the body surface data to yield the potential flow field; (3) a code that computes flow velocities at arrays of points in space; (4) a code that computes water drop trajectories from an array of points in space; (5) a code that computes water drop trajectories and fluxes to arbitrary target points; (6) a code that computes water drop trajectories tangent to the body; and (7) a code that produces stereo pair plots which include both the body and trajectories. Accuracy of the calculations is discussed, and trajectory calculation results are compared with prior calculations and with experimental data.

  2. Microfiltration and Ultrafiltration Membranes for Drinking Water

    EPA Science Inventory

    This article provides a concise and abbreviated summary of AWWA Manual of Practice M53, Microfiltration and Ultrafiltration Membranes for Drinking Water, to serve as a quick point of reference. For convenience, the article’s organization matches that of M53, as follows: • wate...

  3. Time resolved measurements of particle lift off from the wall in a turbulent water channel flow

    NASA Astrophysics Data System (ADS)

    van Hout, Rene; Rabencov, Boris; Arca, Javier

    2011-11-01

    Time-Resolved Particle Image Velocimetry (TR-PIV) and digital holography measurements were carried out in a dilute particle-laden flow tracking both Polystyrene Spheres (PS, ~0.583 mm, d+ ~ 10) as well as resolving the instantaneous velocity field of the turbulent flow. Measurements were performed in a closed loop, transparent, square channel facility (50x50 mm2) at 127.5cm from the inlet with bulk water velocity 0.3 m/s (Reh = 7353) and friction velocity 0.0174 m/s. Data were captured at 1 kHz, corresponding to a time scale 5x smaller than the flow's viscous scale. Single view digital holographic cinematography was used to track the 3D PS motion inside the VOI (17x17x50 mm3) including the wall bottom. TR-PIV in a vertical plane (29.3x29.3 mm2) oriented along the channel's centerline imaged PS together with flow tracers. Discrimination was based on their size difference. Instantaneous sequences of PS plotted on the spatial velocity, vorticity and swirling strength maps showed the effect of turbulent flow structures and resulting particle movement. Results are presented for particles that lift off from the bottom wall as a result of complex interaction with ejection and sweep motions.

  4. Thermoelectric integrated membrane evaporation water recovery technology

    NASA Technical Reports Server (NTRS)

    Roebelen, G. J., Jr.; Winkler, H. E.; Dehner, G. F.

    1982-01-01

    The recently developed Thermoelectric Integrated Membrane Evaporation Subsystem (TIMES) offers a highly competitive approach to water recovery from waste fluids for future on-orbit stations such as the Space Operations Center. Low power, compactness and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber membrane evaporator with a thermoelectric heat pump. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than pumps and an accumulator, thus solving problems inherent in other reclamation subsystem designs. In an extensive test program, over 850 hours of operation were accumulated during which time high quality product water was recovered from both urine and wash water at an average steady state production rate of 2.2 pounds per hour.

  5. The measured field performances of eight different mechanical and air-lift water-pumping wind-turbines

    SciTech Connect

    Kentfield, J.A.C.

    1996-12-31

    Results are presented of the specific performances of eight, different, water-pumping wind-turbines subjected to impartial tests at the Alberta Renewable Energy Test Site (ARETS), Alberta, Canada. The results presented which were derived from the test data, obtained independently of the equipment manufacturers, are expressed per unit of rotor projected area to eliminate the influence of machine size. Hub-height wind speeds and water flow rates for a common lift of 5.5 m (18 ft) constitute the essential test data. A general finding was that, to a first approximation, there were no major differences in specific performance between four units equipped with conventional reciprocating pumps two of which employed reduction gearing and two of which did not. It was found that a unit equipped with a Moyno pump performed well but three air-lift machines had, as was expected, poorer specific performances than the more conventional equipment. 10 refs., 9 figs.

  6. Carbon Nanotube Membranes for Water Purification

    NASA Astrophysics Data System (ADS)

    Bakajin, Olgica

    2009-03-01

    Carbon nanotubes are an excellent platform for the fundamental studies of transport through channels commensurate with molecular size. Water transport through carbon nanotubes is also believed to be similar to transport in biological channels such as aquaporins. I will discuss the transport of gas, water and ions through microfabricated membranes with sub-2 nanometer aligned carbon nanotubes as ideal atomically-smooth pores. The measured gas flow through carbon nanotubes exceeded predictions of the Knudsen diffusion model by more than an order of magnitude. The measured water flow exceeded values calculated from continuum hydrodynamics models by more than three orders of magnitude and is comparable to flow rates extrapolated from molecular dynamics simulations and measured for aquaporins. More recent reverse osmosis experiments reveal ion rejection by our membranes. Based on our experimental findings, the current understanding of the fundamentals of water and gas transport and of ion rejection will be discussed. The potential application space that exploits these unique nanofluidic phenomena will be explored. The extremely high permeabilities of these membranes, combined with their small pore size will enable energy efficient filtration and eventually decrease the cost of water purification.[4pt] In collaboration with Francesco Fornasiero, Biosciences and Biotechnology Division, PLS, LLNL, Livermore, CA 94550; Sangil Kim, NSF Center for Biophotonics Science & Technology, University of California at Davis, Sacramento CA 95817; Jung Bin In, Mechanical Engineering Department, UC Berkeley, Berkeley CA 94720; Hyung Gyu Park, Jason K Holt, and Michael Stadermann, Biosciences and Biotechnology Division, PLS, LLNL; Costas P. Grigoropoulos, Mechanical Engineering Department, UC Berkeley; Aleksandr Noy, Biosciences and Biotechnology Division, PLS, LLNL and School of Natural Sciences, University of California at Merced.

  7. Evaluations of membrane fouling potential in water treatment applications

    SciTech Connect

    Tu, S.C.; Ravindran, V.; Pirbazari, M.

    1999-07-01

    Membrane processes such as ultrafiltration, nanofiltration, and reverse osmosis are becoming increasingly popular in water treatment utilities because of their ability to produce high finished water quality. A major problem affecting the economics of these processes is permeate flux decline due to membrane fouling. The types of membrane fouling can be broadly categorized as follows: organic fouling, biofouling, colloidal fouling, inorganic fouling, and precipitation scaling. The membrane performance with respect to resistance to fouling as well as rejection characteristics is an important consideration. Selection of appropriate membranes for performance improvement in water treatment applications mandates the evaluation of the fouling potential, an aspect related to the membrane material, membrane type, nature of feed solution, and interactions between membranes and solutes. In the present study, the membrane fouling potential is evaluated by membrane performance tests with respect to permeate flux and solute rejections, and by membrane surface characterization techniques including measurements of membrane sorption, zeta potential, contact angles, and membrane surface morphology. These surface characterization techniques are intended to evaluate membrane sorption characteristics (with respect to foulants), membrane surface hydrophobicity, membrane surface charge under different solution conditions, and changes on membrane surface topography on the clean and fouled membranes.

  8. Hollow-Fiber Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Settles, Joseph

    2013-01-01

    The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

  9. Origin of subdiffusion of water molecules on cell membrane surfaces

    PubMed Central

    Yamamoto, Eiji; Akimoto, Takuma; Yasui, Masato; Yasuoka, Kenji

    2014-01-01

    Water molecules play an important role in providing unique environments for biological reactions on cell membranes. It is widely believed that water molecules form bridges that connect lipid molecules and stabilize cell membranes. Using all-atom molecular dynamics simulations, we show that translational and rotational diffusion of water molecules on lipid membrane surfaces exhibit subdiffusion and aging. Moreover, we provide evidence that both divergent mean trapping time (continuous-time random walk) and long-correlated noise (fractional Brownian motion) contribute to this subdiffusion. These results suggest that subdiffusion on cell membranes causes the water retardation, an enhancement of cell membrane stability, and a higher reaction efficiency. PMID:24739933

  10. Process Intensification with Integrated Water-Gas-Shift Membrane Reactor

    SciTech Connect

    2009-11-01

    This factsheet describes a research project whose objective is to develop hydrogen-selective membranes for an innovative gas-separation process based on a water-gas-shift membrane reactor (WGS-MR) for the production of hydrogen.

  11. Water permeation through single-layer graphyne membrane

    NASA Astrophysics Data System (ADS)

    Kou, Jianlong; Zhou, Xiaoyan; Chen, Yanyan; Lu, Hangjun; Wu, Fengmin; Fan, Jintu

    2013-08-01

    We report the molecular dynamics simulations of spontaneous and continuous permeation of water molecules through a single-layer graphyne-3 membrane. We found that the graphyne-3 membrane is more permeable to water molecules than (5, 5) carbon nanotube membranes of similar pore diameter. The remarkable hydraulic permeability of the single-layer graphyne-3 membrane is attributed to the hydrogen bond formation, which connects the water molecules on both sides of the monolayer graphyne-3 membrane and aids to overcome the resistance of the nanopores, and to the relatively lower energy barrier at the pore entrance. Consequently, the single-layer graphyne-3 membrane has a great potential for application as membranes for desalination of sea water, filtration of polluted water, etc.

  12. The Variation Characteristic of Sulfides and VOSc in a Source Water Reservoir and Its Control Using a Water-Lifting Aerator

    PubMed Central

    Shi, Jian-Chao; Huang, Ting-Lin; Wen, Gang; Liu, Fei; Qiu, Xiao-Peng; Wang, Bao-Shan

    2016-01-01

    Sulfides and volatile organic sulfur compounds (VOSc) in water are not only malodorous but also toxic to humans and aquatic organisms. They cause serious deterioration in the ecological environment and pollute drinking water sources. In the present study, a source water reservoir—Zhoucun Reservoir in East China—was selected as the study site. Through a combination of field monitoring and in situ release experiments of sulfides, the characteristics of seasonal variation and distribution of sulfides and VOSc in the reservoir were studied, and the cause of the sulfide pollution was explained. The results show that sulfide pollution was quite severe in August and September 2014 in the Zhoucun Reservoir, with up to 1.59 mg·L−1 of sulfides in the lower layer water. The main source of sulfides is endogenous pollution. VOSc concentration correlates very well with that of sulfides during the summer, with a peak VOSc concentration of 44.37 μg·L−1. An installed water-lifting aeration system was shown to directly oxygenate the lower layer water, as well as mix water from the lower and the upper layers. Finally, the principle and results of controlling sulfides and VOSc in reservoirs using water-lifting aerators are clarified. Information about sulfides and VOSc fluctuation and control gained in this study may be applicable to similar reservoirs, and useful in practical water quality improvement and pollution prevention. PMID:27092517

  13. The Variation Characteristic of Sulfides and VOSc in a Source Water Reservoir and Its Control Using a Water-Lifting Aerator.

    PubMed

    Shi, Jian-Chao; Huang, Ting-Lin; Wen, Gang; Liu, Fei; Qiu, Xiao-Peng; Wang, Bao-Shan

    2016-04-15

    Sulfides and volatile organic sulfur compounds (VOSc) in water are not only malodorous but also toxic to humans and aquatic organisms. They cause serious deterioration in the ecological environment and pollute drinking water sources. In the present study, a source water reservoir--Zhoucun Reservoir in East China--was selected as the study site. Through a combination of field monitoring and in situ release experiments of sulfides, the characteristics of seasonal variation and distribution of sulfides and VOSc in the reservoir were studied, and the cause of the sulfide pollution was explained. The results show that sulfide pollution was quite severe in August and September 2014 in the Zhoucun Reservoir, with up to 1.59 mg·L(-1) of sulfides in the lower layer water. The main source of sulfides is endogenous pollution. VOSc concentration correlates very well with that of sulfides during the summer, with a peak VOSc concentration of 44.37 μg·L(-1). An installed water-lifting aeration system was shown to directly oxygenate the lower layer water, as well as mix water from the lower and the upper layers. Finally, the principle and results of controlling sulfides and VOSc in reservoirs using water-lifting aerators are clarified. Information about sulfides and VOSc fluctuation and control gained in this study may be applicable to similar reservoirs, and useful in practical water quality improvement and pollution prevention.

  14. Membrane water deaerator investigation. [fluid filter breadboard model

    NASA Technical Reports Server (NTRS)

    Elam, J.; Ruder, J.; Strumpf, H.

    1974-01-01

    The purpose of the membrane water deaerator program was to develop data on a breadboard hollow fiber membrane unit that removes both dissolved and evolved gas from a water transfer system in order to: (1) assure a hard fill of the EVLSS expendable water tank; (2) prevent flow blockage by gas bubbles in circulating systems; and (3) prevent pump cavitation.

  15. Advanced Water-Gas Shift Membrane Reactor

    SciTech Connect

    Sean Emerson; Thomas Vanderspurt; Susanne Opalka; Rakesh Radhakrishnan; Rhonda Willigan

    2009-01-07

    The overall objectives for this project were: (1) to identify a suitable PdCu tri-metallic alloy membrane with high stability and commercially relevant hydrogen permeation in the presence of trace amounts of carbon monoxide and sulfur; and (2) to identify and synthesize a water gas shift catalyst with a high operating life that is sulfur and chlorine tolerant at low concentrations of these impurities. This work successfully achieved the first project objective to identify a suitable PdCu tri-metallic alloy membrane composition, Pd{sub 0.47}Cu{sub 0.52}G5{sub 0.01}, that was selected based on atomistic and thermodynamic modeling alone. The second objective was partially successful in that catalysts were identified and evaluated that can withstand sulfur in high concentrations and at high pressures, but a long operating life was not achieved at the end of the project. From the limited durability testing it appears that the best catalyst, Pt-Re/Ce{sub 0.333}Zr{sub 0.333}E4{sub 0.333}O{sub 2}, is unable to maintain a long operating life at space velocities of 200,000 h{sup -1}. The reasons for the low durability do not appear to be related to the high concentrations of H{sub 2}S, but rather due to the high operating pressure and the influence the pressure has on the WGS reaction at this space velocity.

  16. Forehead lift

    MedlinePlus

    ... both sides even. If you have already had plastic surgery to lift your upper eyelids, a forehead ... Managing the cosmetic patient. In: Neligan PC, ed. Plastic Surgery . 3rd ed. Philadelphia, PA: Elsevier Saunders; 2013: ...

  17. Buttock Lift

    MedlinePlus

    ... after surgery using a needle and syringe. Poor wound healing. Sometimes areas along the incision line heal poorly ... might be given antibiotics if there is a wound healing problem. Scarring. Incision scars from a buttock lift ...

  18. Fouling-tolerant nanofibrous polymer membranes for water treatment.

    PubMed

    Lee, Jang-Woo; Jung, Jiyoung; Cho, Young Hoon; Yadav, Santosh Kumar; Baek, Kyung Youl; Park, Ho Bum; Hong, Soon Man; Koo, Chong Min

    2014-08-27

    Nafion/polyvinylidene fluoride (PVDF) nanofibrous membranes with electrostatically negative charges on the fiber surface were fabricated via electrospinning with superior water permeability and antifouling behaviors in comparison with the conventional microfiltration membranes. The fiber diameter and the resultant pore size in the nanofibrous membranes were easily controlled through tailoring the properties of the electrospinning solutions. The electrospun Nafion/PVDF nanofibrous membranes revealed high porosities (>80%) and high densities of sulfonate groups on the membrane surface, leading to praiseworthy water permeability. Unexpectedly, the water permeability was observed as proportional to the fiber diameter and pore size in the membrane. The presence of sulfonate groups on the membrane improved the antifouling performance against negatively charged oily foulants.

  19. Selective sorption of latex membranes with ethanol-water mixtures

    SciTech Connect

    Wei, Y.; Huang, R.Y.M. )

    1994-02-01

    Latex membranes have recently found use in pervaporation separation. The sorption of water-ethanol mixtures to latex membranes was carried out on three types of latex membranes, poly(acrylonitrile-co-butyl acrylate) [P(AN-BuA)], poly(methyl methacrylate-co-butyl acrylate) [P(MMA-BuA)], and poly(styrene-co-butyl acrylate) [P(ST-BuA)], which were prepared in our laboratory by direct casting of polymer latexes synthesized by emulsion polymerization. These latex membranes all exhibit preferential sorption and permeation toward water. Both water and ethanol sorption to the latex membranes exhibited nonideal sorption, with water sorption being enhanced greatly by the presence of ethanol. It was shown that the solubility parameter theory did not give correct predictions for the preferential sorption of latex membranes. Better results were obtained by using the Flory-Huggins interaction parameter. 12 refs., 4 figs., 2 tabs.

  20. Interfacial Water-Transport Effects in Proton-Exchange Membranes

    SciTech Connect

    Kienitz, Brian; Yamada, Haruhiko; Nonoyama, Nobuaki; Weber, Adam

    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. 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.

  1. Effect of Schneiderian membrane perforation on sinus lift graft outcome using two different donor sites: a retrospective study of 105 maxillary sinus elevation procedures

    PubMed Central

    Sakkas, Andreas; Konstantinidis, Ioannis; Winter, Karsten; Schramm, Alexander; Wilde, Frank

    2016-01-01

    Background: Sinuslift is meanwhile an established method of bone augmentation in the posterior maxilla. Aim of the study was to evaluate the significance of intraoperative Schneiderian membrane perforations during maxillary sinus floor elevation surgery using autogenous bone harvested from two different donor sites using a Safescraper device on the success rate, graft survival and implant integration. Methods: The investigators conducted a retrospective cohort study at the Department of Oral and Maxillofacial Surgery of Military Hospital Ulm composed of patients with severe maxillary atrophy who underwent sinus augmentation from January 2011 until December 2011. Ninety-nine consecutive patients (89 men, 10 women) with a mean age of 43.1 years underwent sinus graft procedures in a 2-stage procedure using the lateral wall approach, as described by Tatum (1986). Data on patient age, smoking status, donor site and surgical complications were recorded and the relationship between Schneiderian membrane perforation and complication rate was evaluated. Dental implants were inserted 4 months after grafting. Results: A total of 105 sinus lift procedures were performed in 99 patients. Sixty-one patients (61.6%) underwent sinus elevation with autogenous bone from the buccal sinus wall, while 38 patients (38.4%) bone harvesting from the iliac crest. Intraoperative perforation of the Schneiderian membrane was observed in 11 of the 105 sinuses (10.4%). These perforations resulted in 4 (36.3%) of the cases in major postoperative complications accompanied by swelling and wound infection. Membrane perforations were slightly associated with the appearance of postoperative complications (p=0.0762). In 2.4% of all cases, regarding 2 patients the final rehabilitation with dental implants was not possible because of extensive bone resorption. Conclusion: Intraoperative complications performing sinus augmentation may lead to postoperative complications. With careful clinical and

  2. Water desalination by air-gap membrane distillation using meltblown polypropylene nanofiber membrane

    NASA Astrophysics Data System (ADS)

    Rosalam, S.; Chiam, C. K.; Widyaparamitha, S.; Chang, Y. W.; Lee, C. A.

    2016-06-01

    This paper presents a study of air gap membrane distillation (AGMD) using meltblown polypropylene (PP) nanofiber membrane to produce fresh water via desalination process. PP nanofiber membranes with the effective area 0.17 m2 are tested with NaCl solutions (0.5 - 4.0 wt.%) and seawater as the feed solutions (9400 - 64800 μS/cm) in a tubular membrane module. Results show that the flux decreases with increasing the membrane thickness from 547 to 784 μm. The flux increases with the feed flow rate and temperature difference across the membrane. The feed concentration affects the flux insignificantly. The AGMD system can reject the salts at least 96%. Water vapor permeation rate is relatively higher than solute permeation rate resulting in the conductivity value of permeate decreases when the corresponding flux increases. The AGMD system produces the fresh water (200 - 1520 μS/cm) that is suitable for drinking, fisheries or irrigation.

  3. Modeling of membrane processes for air revitalization and water recovery

    NASA Technical Reports Server (NTRS)

    Lange, Kevin E.; Foerg, Sandra L.; Dall-Bauman, Liese A.

    1992-01-01

    Gas-separation and reverse-osmosis membrane models are being developed in conjunction with membrane testing at NASA JSC. The completed gas-separation membrane model extracts effective component permeabilities from multicomponent test data, and predicts the effects of flow configuration, operating conditions, and membrane dimensions on module performance. Variable feed- and permeate-side pressures are considered. The model has been applied to test data for hollow-fiber membrane modules with simulated cabin-air feeds. Results are presented for a membrane designed for air drying applications. Extracted permeabilities are used to predict the effect of operating conditions on water enrichment in the permeate. A first-order reverse-osmosis model has been applied to test data for spiral wound membrane modules with a simulated hygiene water feed. The model estimates an effective local component rejection coefficient under pseudosteady-state conditions. Results are used to define requirements for a detailed reverse-osmosis model.

  4. Removal of glyphosate herbicide from water using biopolymer membranes.

    PubMed

    Carneiro, Rafael T A; Taketa, Thiago B; Gomes Neto, Reginaldo J; Oliveira, Jhones L; Campos, Estefânia V R; de Moraes, Mariana A; da Silva, Camila M G; Beppu, Marisa M; Fraceto, Leonardo F

    2015-03-15

    Enormous amounts of pesticides are manufactured and used worldwide, some of which reach soils and aquatic systems. Glyphosate is a non-selective herbicide that is effective against all types of weeds and has been used for many years. It can therefore be found as a contaminant in water, and procedures are required for its removal. This work investigates the use of biopolymeric membranes prepared with chitosan (CS), alginate (AG), and a chitosan/alginate combination (CS/AG) for the adsorption of glyphosate present in water samples. The adsorption of glyphosate by the different membranes was investigated using the pseudo-first order and pseudo-second order kinetic models, as well as the Langmuir and Freundlich isotherm models. The membranes were characterized regarding membrane solubility, swelling, mechanical, chemical and morphological properties. The results of kinetics experiments showed that adsorption equilibrium was reached within 4 h and that the CS membrane presented the best adsorption (10.88 mg of glyphosate/g of membrane), followed by the CS/AG bilayer (8.70 mg of glyphosate/g of membrane). The AG membrane did not show any adsorption capacity for this herbicide. The pseudo-second order model provided good fits to the glyphosate adsorption data on CS and CS/AG membranes, with high correlation coefficient values. Glyphosate adsorption by the membranes could be fitted by the Freundlich isotherm model. There was a high affinity between glyphosate and the CS membrane and moderate affinity in the case of the CS/AG membrane. Physico-chemical characterization of the membranes showed low values of solubility in water, indicating that the membranes are stable and not soluble in water. The SEM and AFM analysis showed evidence of the presence of glyphosate on CS membranes and on chitosan face on CS/AG membranes. The results showed that the glyphosate herbicide can be adsorbed by chitosan membranes and the proposed membrane-based methodology was successfully used to

  5. Molecular level water and solute transport in reverse osmosis membranes

    NASA Astrophysics Data System (ADS)

    Lueptow, Richard M.; Shen, Meng; Keten, Sinan

    2015-11-01

    The water permeability and rejection characteristics of six solutes, methanol, ethanol, 2-propanol, urea, Na+, and Cl-, were studied for a polymeric reverse osmosis (RO) membrane using non-equilibrium molecular dynamics simulations. Results indicate that water flux increases with an increasing fraction of percolated free volume in the membrane polymer structure. Solute molecules display Brownian motion and hop from pore to pore as they pass through the membrane. The solute rejection depends on both the size of the solute molecule and the chemical interaction of the solute with water and the membrane. When the open spaces in the polymeric structure are such that solutes have to shed at least one water molecule from their solvation shell to pass through the membrane molecular structure, the water-solute pair interaction energy governs solute rejection. Organic solutes more easily shed water molecules than ions to more readily pass through the membrane. Hydrogen-bonding sites for molecules like urea also lead to a higher rejection. These findings underline the importance of the solute's solvation shell and solute-water-membrane chemistry in solute transport and rejection in RO membranes. Funded by the Institute for Sustainability and Energy at Northwestern with computing resources from XSEDE (NSF grant ACI-1053575).

  6. Water and polymer dynamics in highly crosslinked polyamide membranes

    NASA Astrophysics Data System (ADS)

    Frieberg, Bradley; Chan, Edwin; Tyagi, Madhu; Stafford, Christopher; Soles, Christopher

    Highly crosslinked polyamides for reverse osmosis are the state-of-the-art active material in membranes for desalination. The thin film composite membrane structure that is used commercially has been empirically designed to selectively allow the passage of water molecules and minimize the passage of solutes such as salt. However, due to the large roughness and variability of the polyamide layer, there is a limited understanding of the structure-property relationship for these materials as well as the transport mechanism. To better understand the water transport mechanism we measure the water and polymer dynamics of polyamide membranes using quasi-elastic neutron scattering (QENS). By hydrating the membrane with deuterated water, we are able to isolate the dynamics of the hydrogenated membrane on the pico- and nanosecond time scales. By subsequently hydrating the membranes with hydrogenated water, the QENS measurements on the same times scales reveal information about both the translational and rotational dynamics of water confined within the polyamide membrane. Further understanding of the water diffusion mechanism will establish design rules in which the performance of future membrane materials can be improved.

  7. Histological and Radiological Analyses of a Maxillary Sinus Lift with Extensive Drilling of the Schneider Membrane Using Xenogeneic Bone

    PubMed Central

    Romano, Marcelo M.; Smanio, Júlia A.; Ferreira, Lorraine B.; Arana-Chavez, Victor E.; Soares, Mário S.

    2014-01-01

    The objective of this study is to report a clinical case of maxillary sinus with lyophilized, xenogeneic graft, in which, despite a large perforation of the sinus membrane, the surgery was not aborted and the results of histological examinations indicate bone neoformation in the surgical area. Results. This case showed that the biomaterials evaluated in this study and the procedure used to place them proved to be biocompatible and presented high osteogenic potential, leading to a successful surgery and osseointegration implant. Conclusion. Positioning Schneider's membrane and filling it with the graft biomaterial helped to achieve the desired osteoconduction and proliferation of bone cells even though the patient had a large perforation of the sinus membrane. PMID:25258686

  8. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...

  9. Tunable water desalination across Graphene Oxide Framework membranes

    SciTech Connect

    Nicolai, Adrien; Sumpter, Bobby G; Meunier, V.

    2014-01-01

    The performance of graphene oxide framework (GOF) membranes for water desalination is assessed using classical molecular dynamics (MD) simulations. The coupling between water permeability and salt rejection GOF membranes is studied as a function of linker concentration n, thickness h and applied pressure DP. The simulations reveal that water permeability in GOF-(n,h) membranes can be tuned from 5 (n = 32 and h = 6.5 nm) to 400 L/cm2/day/MPa (n = 64 and h = 2.5 nm) and follows the law Cnh an . For a given pore size (n = 16 or 32), water permeability of GOF membranes increases when the pore spacing decreases, whereas for a given pore spacing (n = 32 or 64), water permeability increases by up to two orders of magnitude when the pore size increases. Furthermore, for linker concentrations n 32, the high water permeability corresponds to a 100% salt rejection, elevating this type of GOF membrane as an ideal candidate for water desalination. Compared to experimental performance of reverse osmosis membranes, our calculations suggest that under the same conditions of applied pressure and characteristics of membranes (DP 10 MPa and h 100 nm), one can expect a perfect salt rejection coupled to a water permeability two orders of magnitude higher than existing technologies, i.e., from a few cL/cm2/day/MPa to a few L/cm2/day/MPa.

  10. Creating biological membranes on the micron scale: forming patterned lipid bilayers using a polymer lift-off technique.

    PubMed

    Orth, R N; Kameoka, J; Zipfel, W R; Ilic, B; Webb, W W; Clark, T G; Craighead, H G

    2003-11-01

    We present a new method for creating patches of fluid lipid bilayers with conjugated biotin and other compounds down to 1 microm resolution using a photolithographically patterned polymer lift-off technique. The patterns are realized as the polymer is mechanically peeled away in one contiguous piece in solution. The functionality of these surfaces is verified with binding of antibodies and avidin on these uniform micron-scale platforms. The biomaterial patches, measuring 1 micro m-76 microm on edge, provide a synthetic biological substrate for biochemical analysis that is approximately 100x smaller in width than commercial printing technologies. 100 nm unilamellar lipid vesicles spread to form a supported fluid lipid bilayer on oxidized silicon surface as confirmed by fluorescence photobleaching recovery. Fluorescence photobleaching recovery measurements of DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiIC(18)(3))) stained bilayer patches yielded an average diffusion coefficient of 7.54 +/- 1.25 microm(2) s(-1), equal to or slightly faster than typically found in DiI stained cells. This diffusion rate is approximately 3x faster than previous values for bilayers on glass. This method provides a new means to form functionalized fluid lipid bilayers as micron-scale platforms to immobilize biomaterials, capture antibodies and biotinylated reagents from solution, and form antigenic stimuli for cell stimulation.

  11. Water and Molecular Transport across Nanopores in Monolayer Graphene Membranes

    NASA Astrophysics Data System (ADS)

    Jang, Doojoon; O'Hern, Sean; Kidambi, Piran; Boutilier, Michael; Song, Yi; Idrobo, Juan-Carlos; Kong, Jing; Laoui, Tahar; Karnik, Rohit

    2015-11-01

    Graphene's atomic thickness and high tensile strength allow it to outstand as backbone material for next-generation high flux separation membrane. Molecular dynamics simulations predicted that a single-layer graphene membrane could exhibit high permeability and selectivity for water over ions/molecules, qualifying as novel water desalination membranes. However, experimental investigation of water and molecular transport across graphene nanopores had remained barely explored due to the presence of intrinsic defects and tears in graphene. We introduce two-step methods to seal leakage across centimeter scale single-layer graphene membranes create sub-nanometer pores using ion irradiation and oxidative etching. Pore creation parameters were varied to explore the effects of created pore structures on water and molecular transport driven by forward osmosis. The results demonstrate the potential of nanoporous graphene as a reliable platform for high flux nanofiltration membranes.

  12. Plasma treatment of polyethersulfone membrane for benzene removal from water by air gap membrane distillation.

    PubMed

    Pedram, Sara; Mortaheb, Hamid Reza; Arefi-Khonsari, Farzaneh

    2017-03-13

    In order to obtain a durable cost-effective membrane for membrane distillation (MD) process, flat sheet polyethersulfone (PES) membranes were modified by an atmospheric pressure nonequilibrium plasma generated using a dielectric barrier discharge in a mixture of argon and hexamethyldisiloxane as the organosilicon precursor. The surface properties of the plasma-modified membranes were characterized by water contact angle (CA), liquid entry pressure, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The water CA of the membrane was increased from 64° to 104° by depositing a Si(CH3)-rich thin layer. While the pristine PES membrane was not applicable in the MD process, the modified PES membrane could be applied for the first time in an air gap membrane distillation setup for the removal of benzene as a volatile organic compound from water. The experimental design using central composite design and response surface methodology was applied to study the effects of feed temperature, concentration, and flow rate as well as their binary interactions on the overall permeate flux and separation factor. The separation factor and permeation flux of the modified PES membrane at optimum conditions were comparable with those of commercial polytetrafluoroethylene membrane.

  13. Radiation-Grafted Polymer Electrolyte Membranes for Water Electrolysis Cells: Evaluation of Key Membrane Properties.

    PubMed

    Albert, Albert; Barnett, Alejandro O; Thomassen, Magnus S; Schmidt, Thomas J; Gubler, Lorenz

    2015-10-14

    Radiation-grafted membranes can be considered an alternative to perfluorosulfonic acid (PFSA) membranes, such as Nafion, in a solid polymer electrolyte electrolyzer. Styrene, acrylonitrile, and 1,3-diisopropenylbenzene monomers are cografted into preirradiated 50 μm ethylene tetrafluoroethylene (ETFE) base film, followed by sulfonation to introduce proton exchange sites to the obtained grafted films. The incorporation of grafts throughout the thickness is demonstrated by scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analysis of the membrane cross-sections. The membranes are analyzed in terms of grafting kinetics, ion-exchange capacity (IEC), and water uptake. The key properties of radiation-grafted membranes and Nafion, such as gas crossover, area resistance, and mechanical properties, are evaluated and compared. The plot of hydrogen crossover versus area resistance of the membranes results in a property map that indicates the target areas for membrane development for electrolyzer applications. Tensile tests are performed to assess the mechanical properties of the membranes. Finally, these three properties are combined to establish a figure of merit, which indicates that radiation-grafted membranes obtained in the present study are promising candidates with properties superior to those of Nafion membranes. A water electrolysis cell test is performed as proof of principle, including a comparison to a commercial membrane electrode assembly (MEA).

  14. Antifouling membranes for sustainable water purification: strategies and mechanisms.

    PubMed

    Zhang, Runnan; Liu, Yanan; He, Mingrui; Su, Yanlei; Zhao, Xueting; Elimelech, Menachem; Jiang, Zhongyi

    2016-10-24

    One of the greatest challenges to the sustainability of modern society is an inadequate supply of clean water. Due to its energy-saving and cost-effective features, membrane technology has become an indispensable platform technology for water purification, including seawater and brackish water desalination as well as municipal or industrial wastewater treatment. However, membrane fouling, which arises from the nonspecific interaction between membrane surface and foulants, significantly impedes the efficient application of membrane technology. Preparing antifouling membranes is a fundamental strategy to deal with pervasive fouling problems from a variety of foulants. In recent years, major advancements have been made in membrane preparation techniques and in elucidating the antifouling mechanisms of membrane processes, including ultrafiltration, nanofiltration, reverse osmosis and forward osmosis. This review will first introduce the major foulants and the principal mechanisms of membrane fouling, and then highlight the development, current status and future prospects of antifouling membranes, including antifouling strategies, preparation techniques and practical applications. In particular, the strategies and mechanisms for antifouling membranes, including passive fouling resistance and fouling release, active off-surface and on-surface strategies, will be proposed and discussed extensively.

  15. Photo Induced Membrane Separation for Water Purification and Desalination Using Azobenzene Modified Anodized Alumina Membranes.

    PubMed

    Fujiwara, Masahiro; Imura, Tatsuki

    2015-06-23

    Water purification and desalination to produce end-use water are important agendas in 21st century, because the global water shortage is becoming increasingly serious. Those processes using light energy, especially solar energy, without the consumption of fossil fuels are desired for creating sustainable society. For these earth-friendly water treatments, nanoporous materials and membranes are expected to provide new technologies. We have reported before that the repetitive photo isomerization of azobenzene groups between the trans and cis isomers induced by the simultaneous irradiation of UV and visible lights accelerates the molecular movement of nearby molecules in nanoporous materials. After further studies, we recently found that the permeation of water through azobenzene modified anodized alumina membranes as a photo responsive nanoporous membrane was achieved by the simultaneous irradiation of UV and visible lights, while no water penetration occurred under no light, only single UV or visible light. The photo induced permeation of water was promoted by the vaporization of water with the repetitive photo isomerization of azobenzene. This membrane permeation achieved the purification of water solutions, because dye molecules and a protein dissolved in aqueous solutions were not involved in the photo induced penetrated water. When 3.5% of sodium chloride solution as model seawater was employed for this membrane separation, the salt content of the permeated water was less than 0.01% to accomplish the complete desalination of seawater.

  16. Carbon membranes for efficient water-ethanol separation

    NASA Astrophysics Data System (ADS)

    Gravelle, Simon; Yoshida, Hiroaki; Joly, Laurent; Ybert, Christophe; Bocquet, Lydéric

    2016-09-01

    We demonstrate, on the basis of molecular dynamics simulations, the possibility of an efficient water-ethanol separation using nanoporous carbon membranes, namely, carbon nanotube membranes, nanoporous graphene sheets, and multilayer graphene membranes. While these carbon membranes are in general permeable to both pure liquids, they exhibit a counter-intuitive "self-semi-permeability" to water in the presence of water-ethanol mixtures. This originates in a preferred ethanol adsorption in nanoconfinement that prevents water molecules from entering the carbon nanopores. An osmotic pressure is accordingly expressed across the carbon membranes for the water-ethanol mixture, which agrees with the classic van't Hoff type expression. This suggests a robust and versatile membrane-based separation, built on a pressure-driven reverse-osmosis process across these carbon-based membranes. In particular, the recent development of large-scale "graphene-oxide" like membranes then opens an avenue for a versatile and efficient ethanol dehydration using this separation process, with possible application for bio-ethanol fabrication.

  17. Hydraulic lifting device

    NASA Technical Reports Server (NTRS)

    Terrell, Kyle (Inventor)

    1990-01-01

    A piston and cylinder assembly is disclosed which is constructed of polyvinyl chloride that uses local water pressure to perform small lifting tasks. The chamber is either pressurized to extend the piston or depressurized to retract the piston. The present invention is best utilized for raising and lowering toilet seats.

  18. Scalable Production Method for Graphene Oxide Water Vapor Separation Membranes

    SciTech Connect

    Fifield, Leonard S.; Shin, Yongsoon; Liu, Wei; Gotthold, David W.

    2016-01-01

    ABSTRACT

    Membranes for selective water vapor separation were assembled from graphene oxide suspension using techniques compatible with high volume industrial production. The large-diameter graphene oxide flake suspensions were synthesized from graphite materials via relatively efficient chemical oxidation steps with attention paid to maintaining flake size and achieving high graphene oxide concentrations. Graphene oxide membranes produced using scalable casting methods exhibited water vapor flux and water/nitrogen selectivity performance meeting or exceeding that of membranes produced using vacuum-assisted laboratory techniques. (PNNL-SA-117497)

  19. High Surface Area Inorganic Membrane for Water Removal

    SciTech Connect

    2008-12-01

    This factsheet describes a research project whose objective is to demonstrate the fabrication and performance advantages of minichannel planar membrane modules made of porous metallic supports of surface area packing density one order of magnitude higher than the conventional membrane tube. The new, transformational, ceramic/metallic, hybrid membrane technology will be used for water/ethanol separations and reduce energy consumption by >20% over distillation and adsorption.

  20. The State of Water in Proton Conducting Membranes

    SciTech Connect

    Allcock, Harry R.; Benesi, Alan; Macdonald, Digby D.

    2010-08-27

    The research carried out under grant No. DE-FG02-07ER46371, "The State of Water in Proton Conducting Membranes", during the period June 1, 2008 - May 31, 2010 was comprised of three related parts. These are: 1. An examination of the state of water in classical proton conduction membranes with the use of deuterium T1 NMR spectroscopy (Allcock and Benesi groups). 2. A dielectric relaxation examination of the behavior of water in classical ionomer membranes (Macdonald program). 3. Attempts to synthesize new proton-conduction polymers and membranes derived from the polyphosphazene system. (Allcock program) All three are closely related, crucial aspects of the design and development of new and improved polymer electrolyte fuel cell membranes on which the future of fuel cell technology for portable applications depends.

  1. Membranes with Surface-Enhanced Antifouling Properties for Water Purification

    PubMed Central

    Shahkaramipour, Nima; Tran, Thien N.; Ramanan, Sankara; Lin, Haiqing

    2017-01-01

    Membrane technology has emerged as an attractive approach for water purification, while mitigation of fouling is key to lower membrane operating costs. This article reviews various materials with antifouling properties that can be coated or grafted onto the membrane surface to improve the antifouling properties of the membranes and thus, retain high water permeance. These materials can be separated into three categories, hydrophilic materials, such as poly(ethylene glycol), polydopamine and zwitterions, hydrophobic materials, such as fluoropolymers, and amphiphilic materials. The states of water in these materials and the mechanisms for the antifouling properties are discussed. The corresponding approaches to coat or graft these materials on the membrane surface are reviewed, and the materials with promising performance are highlighted. PMID:28273869

  2. Recovery of real dye bath wastewater using integrated membrane process: considering water recovery, membrane fouling and reuse potential of membranes.

    PubMed

    Balcik-Canbolat, Cigdem; Sengezer, Cisel; Sakar, Hacer; Karagunduz, Ahmet; Keskinler, Bulent

    2016-12-30

    It has been recognized by the whole world that textile industry which produce large amounts of wastewater with strong color and toxic organic compounds is a major problematical industry requiring effective treatment solutions. In this study, reverse osmosis (RO) membranes were tested on biologically treated real dye bath wastewater with and without pretreatment by nanofiltration (NF) membrane to recovery. Also membrane fouling and reuse potential of membranes were investigated by multiple filtrations. Obtained results showed that only NF is not suitable to produce enough quality to reuse the wastewater in a textile industry as process water while RO provide successfully enough permeate quality. The results recommend that integrated NF/RO membrane process is able to reduce membrane fouling and allow long-term operation for real dye bath wastewater.

  3. Structural and thermodynamic properties of water-membrane interphases: significance for peptide/membrane interactions.

    PubMed

    Disalvo, E A; Martini, M F; Bouchet, A M; Hollmann, A; Frías, M A

    2014-09-01

    Water appears as a common intermediary in the mechanisms of interaction of proteins and polypeptides with membranes of different lipid composition. In this review, how water modulates the interaction of peptides and proteins with lipid membranes is discussed by correlating the thermodynamic response and the structural changes of water at the membrane interphases. The thermodynamic properties of the lipid-protein interaction are governed by changes in the water activity of monolayers of different lipid composition according to the lateral surface pressure. In this context, different water populations can be characterized below and above the phase transition temperature in relation to the CH₂ conformers' states in the acyl chains. According to water species present at the interphase, lipid membrane acts as a water state regulator, which determines the interfacial water domains in the surface. It is proposed that those domains are formed by the contact between lipids themselves and between lipids and the water phase, which are needed to trigger adsorption-insertion processes. The water domains are essential to maintain functional dynamical properties and are formed by water beyond the hydration shell of the lipid head groups. These confined water domains probably carries information in local units in relation to the lipid composition thus accounting for the link between lipidomics and aquaomics. The analysis of these results contributes to a new insight of the lipid bilayer as a non-autonomous, responsive (reactive) structure that correlates with the dynamical properties of a living system.

  4. Ultrafast permeation of water through protein-based membranes

    NASA Astrophysics Data System (ADS)

    Peng, Xinsheng; Jin, Jian; Nakamura, Yoshimichi; Ohno, Takahisa; Ichinose, Izumi

    2009-06-01

    Pressure-driven filtration by porous membranes is widely used in the production of drinking water from ground and surface water. Permeation theory predicts that filtration rate is proportional to the pressure difference across the filtration membrane and inversely proportional to the thickness of the membrane. However, these membranes need to be able to withstand high water fluxes and pressures, which means that the active separation layers in commercial filtration systems typically have a thickness of a few tens to several hundreds of nanometres. Filtration performance might be improved by the use of ultrathin porous silicon membranes or carbon nanotubes immobilized in silicon nitride or polymer films, but these structures are difficult to fabricate. Here, we report a new type of filtration membrane made of crosslinked proteins that are mechanically robust and contain channels with diameters of less than 2.2 nm. We find that a 60-nm-thick membrane can concentrate aqueous dyes from fluxes up to 9,000 l h-1 m-2 bar-1, which is ~1,000 times higher than the fluxes that can be withstood by commercial filtration membranes with similar rejection properties. Based on these results and molecular dynamics simulations, we propose that protein-surrounded channels with effective lengths of less than 5.8 nm can separate dye molecules while allowing the ultrafast permeation of water at applied pressures of less than 1 bar.

  5. Why Hydrophilic Water can Permeate Hydrophobic Interior of Lipid Membranes

    NASA Astrophysics Data System (ADS)

    Qiao, Baofu; Olvera de La Cruz, Monica

    2014-03-01

    Water molecules as well as some small molecules have long been found to be able to diffuse across lipid membranes. Such permeation is of significant biological and biotechnological importance. For instance, the permeation of water across lipid membrane plays a important role in regulating ionic concentrations inside of cells. Such water permeation without the assistance of proteins embedded in membranes has been found to be a energetically unfavorable process. We, for the first time, explicitly depict the driving force for such an energetically unfavorable process. Atomistic molecular dynamics simulations are employed to investigate water diffusion in both liquid-crystalline and ordered gel phases of membranes containing zwitterionic DPPC or anionic DLPS lipid. The membrane conformation is calculated to have a critical role in water permeation, regardless of the type of lipid. The fluctuations in the potential energy are found to have a significant, if not the exclusive, role in the transportation of water across lipid membranes. Our results are also informative for the diffusion of small molecules of CO2, O2 and drug molecules, the absence of diffusion of ions, and the diffusion of water into the hydrophobic pores of carbon nanotubes. The authors acknowledge the support from the Office of the Director of Defense Research and Engineering (DDR & E) under Award No. FA9550-10-1-0167.

  6. Understanding the Permeation of Solutes in Water Treatment Membranes

    NASA Astrophysics Data System (ADS)

    Phillip, William

    2013-03-01

    The responsible management of the world's water resources is essential to supporting human life on earth. The successful development of reverse osmosis seawater desalination makes it a crucial component in the portfolio of water supply options. However, other measures to alleviate the stresses on water supplies are necessary to responsibly and sustainably meet the worldwide demand for fresh water. Osmotically driven membrane processes (ODMP) are an emerging set of technologies that show promise in water conservation and reuse, as well as wastewater reclamation. The majority of research in the field has focused on predicting and enhancing water permeation through membranes, however, the effective operation of ODMP systems requires that the permeation of solutes across water treatment membranes be better understood. For example, the reverse flux of draw solute from the concentrated draw solution into the feed solution should be minimized. Additionally, due to the presence of solute-solute interactions that arise because of the unique geometry of ODMPs, the rejection of dilute solutes in these processes can be dramatically different than those observed in traditional pressure driven operations. In this talk, theoretical and experimental approaches are used to explore the permeation of solutes in osmotically driven membrane processes. Phenomenological models were developed that describe the forward and reverse permeation of the solutes across an asymmetric membrane in forward osmosis operation; and experiments were carried out to validate the model predictions. Using independently determined membrane transport coefficients, strong agreement between the model predictions and experimental results was observed.

  7. Membrane augmented distillation to separate solvents from water

    SciTech Connect

    Huang, Yu; Baker, Richard W.; Daniels, Rami; Aldajani, Tiem; Ly, Jennifer H.; Alvarez, Franklin R.; Vane, Leland M.

    2012-09-11

    Processes for removing water from organic solvents, such as ethanol. The processes include distillation to form a rectified overhead vapor, compression of the rectified vapor, and treatment of the compressed vapor by two sequential membrane separation steps.

  8. Hygro-responsive membranes for effective oil-water separation.

    PubMed

    Kota, Arun K; Kwon, Gibum; Choi, Wonjae; Mabry, Joseph M; Tuteja, Anish

    2012-01-01

    There is a critical need for new energy-efficient solutions to separate oil-water mixtures, especially those stabilized by surfactants. Traditional membrane-based separation technologies are energy-intensive and limited, either by fouling or by the inability of a single membrane to separate all types of oil-water mixtures. Here we report membranes with hygro-responsive surfaces, which are both superhydrophilic and superoleophobic, in air and under water. Our membranes can separate, for the first time, a range of different oil-water mixtures in a single-unit operation, with >99.9% separation efficiency, by using the difference in capillary forces acting on the two phases. Our separation methodology is solely gravity-driven and consequently is expected to be highly energy-efficient. We anticipate that our separation methodology will have numerous applications, including the clean-up of oil spills, wastewater treatment, fuel purification and the separation of commercially relevant emulsions.

  9. Prism-patterned Nafion membrane for enhanced water transport in polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Kim, Sang Moon; Kang, Yun Sik; Ahn, Chiyeong; Jang, Segeun; Kim, Minhyoung; Sung, Yung-Eun; Yoo, Sung Jong; Choi, Mansoo

    2016-06-01

    Here, we report a simple and effective strategy to enhance the performance of the polymer electrolyte membrane fuel cell by imprinting prism-patterned arrays onto the Nafion membrane, which provides three combined effects directly related to the device performance. First, a locally thinned membrane via imprinted micro prism-structures lead to reduced membrane resistance, which is confirmed by electrochemical impedance spectroscopy. Second, increments of the geometrical surface area of the prism-patterned Nafion membrane compared to a flat membrane result in the increase in the electrochemical active surface area. Third, the vertically asymmetric geometry of prism structures in the cathode catalyst layer lead to enhanced water transport, which is confirmed by oxygen gain calculation. To explain the enhanced water transport, we propose a simple theoretical model on removal of water droplets existing in the asymmetric catalyst layer. These three combined effects achieved via incorporating prism patterned arrays into the Nafion membrane effectively enhance the performance of the polymer electrolyte membrane fuel cell.

  10. Removal of alkanes from drinking water using membrane technologies

    SciTech Connect

    Fronk, C.A.

    1995-10-01

    Increasingly, the public is concerned about the quality of its drinking water. The chlorinated alkanes are saturated, aliphatic, synthetic organic compounds (SOC`s). When hydrocarbon feedstocks are chlorinated, a wide variety of chlorocarbons and chlorohydrocarbons are produced that are used as industrial solvents, degreasers and intermediaries. Because compounds such as Carbon Tetrachloride and 1,2-Dichloroethane are widely used, they often find their way into drinking water, particularly groundwaters. Surface waters are somewhat less affected bemuse of the high volatility of many chlorinated alkanes. The Drinking Water Research Division is responsible for evaluating various membrane technologies that may be feasible for meeting Maximum Contaminant Levels. Several membrane processes are under investigation to determine their effectiveness in removing SOC`s from drinking water. One study addressed the removal of a variety of alkanes from spiked groundwater by six reverse osmosis membranes: a cellulose acetate, a polyamide (hollow fiber), and four different types of thin-film composite membranes. Progressive chlorination of methanes, ethanes and propanes produces compounds that exhibit differing physicochemical properties. The differences in compound properties have an effect on the removal of these compounds by reverse osmosis membranes. For example only 25% of the methylene chloride (Dichloromethane) was removed by one thin-film composite versus 90% removal of the carbon tetrachloride. In addition, the various membranes are made of different polymeric materials and showed a wide range of removals. Generally, the thin-film composite membranes out performed the other membranes and the more highly chlorinated the compound the better the removal. Pervaporation is yet another membrane process that may prove effective in removal of alkanes and future studies will address its usefulness as a drinking water.

  11. HYDROGEN ISOTOPE RECOVERY USING PROTON EXCHANGE MEMBRANE ELECTROLYSIS OF WATER

    SciTech Connect

    Fox, E; Scott Greenway, S; Amy Ekechukwu, A

    2007-08-27

    A critical component of tritium glovebox operations is the recovery of high value tritium from the water vapor in the glove box atmosphere. One proposed method to improve existing tritium recovery systems is to replace the disposable hot magnesium beds used to separate the hydrogen and oxygen in water with continuous use Proton Exchange Membrane Electrolyzers (PEMEs). This study examines radiation exposure to the membrane of a PEME and examines the sizing difference that would be needed if the electrolyzer were operated with a cathode water vapor feed instead of an anode liquid water feed.

  12. Vapor compression distiller and membrane technology for water revitalization

    NASA Technical Reports Server (NTRS)

    Ashida, A.; Mitani, K.; Ebara, K.; Kurokawa, H.; Sawada, I.; Kashiwagi, H.; Tsuji, T.; Hayashi, S.; Otsubo, K.; Nitta, K.

    1987-01-01

    Water revitalization for a space station can consist of membrane filtration processes and a distillation process. Water recycling equipment using membrane filtration processes was manufactured for ground testing. It was assembled using commercially available components. Two systems for the distillation are studied: one is absorption type thermopervaporation cell and the other is a vapor compression distiller. Absorption type thermopervaporation, able to easily produce condensed water under zero gravity, was investigated experimentally and through simulated calculation. The vapor compression distiller was studied experimentally and it offers significant energy savings for evaporation of water.

  13. Separation of tritiated water using graphene oxide membrane

    SciTech Connect

    Sevigny, Gary J.; Motkuri, Radha K.; Gotthold, David W.; Fifield, Leonard S.; Frost, Anthony P.; Bratton, Wesley

    2015-06-28

    In future nuclear fuel reprocessing plants and possibly for nuclear power plants, the cleanup of tritiated water will be needed for hundreds of thousands of gallons of water with low activities of tritium. This cleanup concept utilizes graphene oxide laminar membranes (GOx) for the separation of low-concentration (10-3-10 µCi/g) tritiated water to create water that can be released to the environment and a much smaller waste stream with higher tritium concentrations. Graphene oxide membranes consist of hierarchically stacked, overlapping molecular layers and represent a new class of materials. A permeation rate test was performed with a 2-µm-thick cast Asbury membrane using mixed gas permeability testing with zero air (highly purified atmosphere) and with air humidified with either H2O or D2O to a nominal 50% relative humidity. The membrane permeability for both H2O and D2O was high with N2 and O2 at the system measurement limit. The membrane water permeation rate was compared to a Nafion® membrane and the GOx permeation was approximately twice as high at room temperature. The H2O vapor permeation rate was 5.9 × 102 cc/m2/min (1.2 × 10-6 g/min-cm2), which is typical for graphene oxide membranes. To demonstrate the feasibility of such isotopic water separation through GOX laminar membranes, an experimental setup was constructed to use pressure-driven separation by heating the isotopic water mixture at one side of the membrane to create steam while cooling the other side. Several membranes were tested and were prepared using different starting materials and by different pretreatment methods. The average separation result was 0.8 for deuterium and 0.6 for tritium. Higher or lower temperatures may also improve separation efficiency but neither has been tested yet. A rough estimate of cost compared to current technology was also included as an indication of potential viability of the process. The relative process costs were based on the rough size of facility to

  14. Membrane-Based Water Evaporator for a Space Suit

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; McCann, Charles J.; O'Connell, Mary K.; Andrea, Scott

    2004-01-01

    A membrane-based water evaporator has been developed that is intended to serve as a heat-rejection device for a space suit. This evaporator would replace the current sublimator that is sensitive to contamination of its feedwater. The design of the membrane-based evaporator takes advantage of recent advances in hydrophobic micropore membranes to provide robust heat rejection with much less sensitivity to contamination. The low contamination sensitivity allows use of the heat transport loop as feedwater, eliminating the need for the separate feedwater system used for the sublimator. A cross section of the evaporator is shown in the accompanying figure. The space-suit cooling loop water flows into a distribution plenum, through a narrow annulus lined on both sides with a hydrophobic membrane, into an exit plenum, and returns to the space suit. Two perforated metal tubes encase the membranes and provide structural strength. Evaporation at the membrane inner surface dissipates the waste heat from the space suit. The water vapor passes through the membrane, into a steam duct and is vented to the vacuum environment through a back-pressure valve. The back-pressure setting can be adjusted to regulate the heat-rejection rate and the water outlet temperature.

  15. Linking ceragenins to water-treatment membranes to minimize biofouling.

    SciTech Connect

    Hibbs, Michael R.; Altman, Susan Jeanne; Feng, Yanshu; Savage, Paul B.; Pollard, Jacob; Branda, Steven S.; Goeres, Darla; Buckingham-Meyer, Kelli; Stafslien, Shane; Marry, Christopher; Jones, Howland D. T.; Lichtenberger, Alyssa; Kirk, Matthew F.; McGrath, Lucas K.

    2012-01-01

    Ceragenins were used to create biofouling resistant water-treatment membranes. Ceragenins are synthetically produced antimicrobial peptide mimics that display broad-spectrum bactericidal activity. While ceragenins have been used on bio-medical devices, use of ceragenins on water-treatment membranes is novel. Biofouling impacts membrane separation processes for many industrial applications such as desalination, waste-water treatment, oil and gas extraction, and power generation. Biofouling results in a loss of permeate flux and increase in energy use. Creation of biofouling resistant membranes will assist in creation of clean water with lower energy usage and energy with lower water usage. Five methods of attaching three different ceragenin molecules were conducted and tested. Biofouling reduction was observed in the majority of the tests, indicating the ceragenins are a viable solution to biofouling on water treatment membranes. Silane direct attachment appears to be the most promising attachment method if a high concentration of CSA-121a is used. Additional refinement of the attachment methods are needed in order to achieve our goal of several log-reduction in biofilm cell density without impacting the membrane flux. Concurrently, biofilm forming bacteria were isolated from source waters relevant for water treatment: wastewater, agricultural drainage, river water, seawater, and brackish groundwater. These isolates can be used for future testing of methods to control biofouling. Once isolated, the ability of the isolates to grow biofilms was tested with high-throughput multiwell methods. Based on these tests, the following species were selected for further testing in tube reactors and CDC reactors: Pseudomonas ssp. (wastewater, agricultural drainage, and Colorado River water), Nocardia coeliaca or Rhodococcus spp. (wastewater), Pseudomonas fluorescens and Hydrogenophaga palleronii (agricultural drainage), Sulfitobacter donghicola, Rhodococcus fascians, Rhodobacter

  16. A carbon nanotube wall membrane for water treatment.

    PubMed

    Lee, Byeongho; Baek, Youngbin; Lee, Minwoo; Jeong, Dae Hong; Lee, Hong H; Yoon, Jeyong; Kim, Yong Hyup

    2015-05-14

    Various forms of carbon nanotubes have been utilized in water treatment applications. The unique characteristics of carbon nanotubes, however, have not been fully exploited for such applications. Here we exploit the characteristics and corresponding attributes of carbon nanotubes to develop a millimetre-thick ultrafiltration membrane that can provide a water permeability that approaches 30,000 l m(-2) h(-1) bar(-1), compared with the best water permeability of 2,400 l m(-2) h(-1) bar(-1) reported for carbon nanotube membranes. The developed membrane consists only of vertically aligned carbon nanotube walls that provide 6-nm-wide inner pores and 7-nm-wide outer pores that form between the walls of the carbon nanotubes when the carbon nanotube forest is densified. The experimental results reveal that the permeance increases as the pore size decreases. The carbon nanotube walls of the membrane are observed to impede bacterial adhesion and resist biofilm formation.

  17. A carbon nanotube wall membrane for water treatment

    NASA Astrophysics Data System (ADS)

    Lee, Byeongho; Baek, Youngbin; Lee, Minwoo; Jeong, Dae Hong; Lee, Hong H.; Yoon, Jeyong; Kim, Yong Hyup

    2015-05-01

    Various forms of carbon nanotubes have been utilized in water treatment applications. The unique characteristics of carbon nanotubes, however, have not been fully exploited for such applications. Here we exploit the characteristics and corresponding attributes of carbon nanotubes to develop a millimetre-thick ultrafiltration membrane that can provide a water permeability that approaches 30,000 l m-2 h-1 bar-1, compared with the best water permeability of 2,400 l m-2 h-1 bar-1 reported for carbon nanotube membranes. The developed membrane consists only of vertically aligned carbon nanotube walls that provide 6-nm-wide inner pores and 7-nm-wide outer pores that form between the walls of the carbon nanotubes when the carbon nanotube forest is densified. The experimental results reveal that the permeance increases as the pore size decreases. The carbon nanotube walls of the membrane are observed to impede bacterial adhesion and resist biofilm formation.

  18. Polymerization and Functionalization of Membrane Pores for Water Related Applications

    PubMed Central

    2015-01-01

    Poly(vinylidene fluoride) (PVDF) was modified by chemical treatments in order to create active double bonds to obtain covalent grafting of poly(acrylic acid) (PAA) on membrane. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrum confirms the formation of conjugated C=C double bonds with surface dehydrofluorination. The membrane morphology was studied by scanning electron microscopy (SEM). The surface composition was characterized by X-ray photoelectron spectroscopy (XPS). The thermal stability of the dehydrofluorinated membrane (Def-PVDF) and functionalized membranes were investigated by differential scanning calorimetry (DSC) analysis. The influence of covalently attached PAA on Def-PVDF membrane has been investigated to determine its effect on the transport of water and charged solute. Variations in the solution pH show an effect on both permeability and solute retention in a reversible fashion. Metal nanoparticles were also immobilized in the membrane for the degradation of toxic chlorinated organics from water. In addition, PVDF membranes with an asymmetric and sponge-like morphology were developed by immersion-precipitation phase-inversion methods in both lab-scale and large-scale. The new type of spongy PVDF membrane shows high surface area with higher yield of PAA functionalization. The ion-capacity with Ca2+ ions was also investigated. PMID:26074669

  19. Polymerization and Functionalization of Membrane Pores for Water Related Applications.

    PubMed

    Xiao, Li; Davenport, Douglas M; Ormsbee, Lindell; Bhattacharyya, Dibakar

    2015-04-29

    Poly(vinylidene fluoride) (PVDF) was modified by chemical treatments in order to create active double bonds to obtain covalent grafting of poly(acrylic acid) (PAA) on membrane. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrum confirms the formation of conjugated C=C double bonds with surface dehydrofluorination. The membrane morphology was studied by scanning electron microscopy (SEM). The surface composition was characterized by X-ray photoelectron spectroscopy (XPS). The thermal stability of the dehydrofluorinated membrane (Def-PVDF) and functionalized membranes were investigated by differential scanning calorimetry (DSC) analysis. The influence of covalently attached PAA on Def-PVDF membrane has been investigated to determine its effect on the transport of water and charged solute. Variations in the solution pH show an effect on both permeability and solute retention in a reversible fashion. Metal nanoparticles were also immobilized in the membrane for the degradation of toxic chlorinated organics from water. In addition, PVDF membranes with an asymmetric and sponge-like morphology were developed by immersion-precipitation phase-inversion methods in both lab-scale and large-scale. The new type of spongy PVDF membrane shows high surface area with higher yield of PAA functionalization. The ion-capacity with Ca(2+) ions was also investigated.

  20. REMOVAL OF CHLORINATED ALKENE SOLVENTS FROM DRINKING WATER BY VARIOUS REVERSE OSMOSIS MEMBRANES

    EPA Science Inventory

    Historically, membranes have been used to desalinate water. As new membrane materials are developed, traditional water treatment schemes may incorporate membrane technologies, such as reverse osmosis, to address a variety of new concerns such as low molecular weight volatile org...

  1. Biological black water treatment combined with membrane separation.

    PubMed

    van Voorthuizen, Ellen; Zwijnenburg, Arie; van der Meer, Walter; Temmink, Hardy

    2008-10-01

    Separate treatment of black (toilet) water offers the possibility to recover energy and nutrients. In this study three combinations of biological treatment and membrane filtration were compared for their biological and membrane performance and nutrient conservation: a UASB followed by effluent membrane filtration, an anaerobic MBR and an aerobic MBR. Methane production in the anaerobic systems was lower than expected. Sludge production was highest in the aerobic MBR, followed by the anaerobic MBR and the UASB-membrane system. The level of nutrient conservation in the effluent was high in all three treatment systems, which is beneficial for their recovery from the effluent. Membrane treatment guaranteed an effluent which is free of suspended and colloidal matter. However, the concentration of soluble COD in the effluent still was relatively high and this may seriously hamper subsequent nutrient recovery by physical-chemical processes. The membrane filtration behaviour of the three systems was very different, and seemed to be dominated by the concentration of colloidals in the membrane feed. In general, membrane fouling was the lowest in the aerobic MBR, followed by the membranes used for UASB effluent filtration and the anaerobic MBR.

  2. Preparation of new composite membranes for water desalination using electrodialysis

    NASA Astrophysics Data System (ADS)

    Klaysom, Chalida; Germain, Leatitia; Burr, Shawn; Ladewig, Bradley P.; Wang, Lianzhou; da Costa, Joe D.; Lu, G. Q. M.

    2008-12-01

    The use of polyethersulfone (PES), an excellent but highly hydrophobic thermoplastic, as a matrix material for ionexchange membranes was investigated. To make PES ion-exchangeable, sulfonate groups were introduced to the polymer chains by sulfonation reaction with chlorosulfonic acid. The degree of sulfonation of sPES was estimated to be 21%. Preliminary experiments investigated the effect of polyethylene glycol (PEG) and Pluronic F127 as fillers to improve the hydrophilicity of the membranes. Moreover, a lab scale electrodialysis cell has been designed and set up to evaluate the performance of these novel membranes compared to the benchmark of commercial membranes. The results show promising properties of ion-exchange capacity, water uptake, conductivity and hydophilicity from blended membranes, comparable to commercial membranes, though the performance of the prepared membranes did not exceed the commercial one. Further characterization of the transport properties of ion-exchange membranes need to be investigated to be able to understand the effects of the fillers on the performance of the membranes in ED application.

  3. Cleaning of Oil Fouling with Water Enabled by Zwitterionic Polyelectrolyte Coatings: Overcoming the Imperative Challenge of Oil-Water Separation Membranes.

    PubMed

    He, Ke; Duan, Haoran; Chen, George Y; Liu, Xiaokong; Yang, Wensheng; Wang, Dayang

    2015-09-22

    Herein we report a self-cleaning coating derived from zwitterionic poly(2-methacryloyloxylethyl phosphorylcholine) (PMPC) brushes grafted on a solid substrate. The PMPC surface not only exhibits complete oil repellency in a water-wetted state (i.e., underwater superoleophobicity), but also allows effective cleaning of oil fouled on dry surfaces by water alone. The PMPC surface was compared with typical underwater superoleophobic surfaces realized with the aid of surface roughening by applying hydrophilic nanostructures and those realized by applying smooth hydrophilic polyelectrolyte multilayers. We show that underwater superoleophobicity of a surface is not sufficient to enable water to clean up oil fouling on a dry surface, because the latter circumstance demands the surface to be able to strongly bond water not only in its pristine state but also in an oil-wetted state. The PMPC surface is unique with its described self-cleaning performance because the zwitterionic phosphorylcholine groups exhibit exceptional binding affinity to water even when they are already wetted by oil. Further, we show that applying this PMPC coating onto steel meshes produces oil-water separation membranes that are resilient to oil contamination with simply water rinsing. Consequently, we provide an effective solution to the oil contamination issue on the oil-water separation membranes, which is an imperative challenge in this field. Thanks to the self-cleaning effect of the PMPC surface, PMPC-coated steel meshes can not only separate oil from oil-water mixtures in a water-wetted state, but also can lift oil out from oil-water mixtures even in a dry state, which is a very promising technology for practical oil-spill remediation. In contrast, we show that oil contamination on conventional hydrophilic oil-water separation membranes would permanently induce the loss of oil-water separation function, and thus they have to be always used in a completely water-wetted state, which significantly

  4. Proton conducting membranes for high temperature fuel cells with solid state water free membranes

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram R. (Inventor); Yen, Shiao-Pin S. (Inventor)

    2006-01-01

    A water free, proton conducting membrane for use in a fuel cell is fabricated as a highly conducting sheet of converted solid state organic amine salt, such as converted acid salt of triethylenediamine with two quaternized tertiary nitrogen atoms, combined with a nanoparticulate oxide and a stable binder combined with the converted solid state organic amine salt to form a polymeric electrolyte membrane. In one embodiment the membrane is derived from triethylenediamine sulfate, hydrogen phosphate or trifiate, an oxoanion with at least one ionizable hydrogen, organic tertiary amine bisulfate, polymeric quaternized amine bisulfate or phosphate, or polymeric organic compounds with quaternizable nitrogen combined with Nafion to form an intimate network with ionic interactions.

  5. Reverse osmosis membrane of high urea rejection properties. [water purification

    NASA Technical Reports Server (NTRS)

    Johnson, C. C.; Wydeven, T. J. (Inventor)

    1980-01-01

    Polymeric membranes suitable for use in reverse osmosis water purification because of their high urea and salt rejection properties are prepared by generating a plasma of an unsaturated hydrocarbon monomer and nitrogen gas from an electrical source. A polymeric membrane is formed by depositing a polymer of the unsaturated monomer from the plasma onto a substrate, so that nitrogen from the nitrogen gas is incorporated within the polymer in a chemically combined form.

  6. Design of a high-lift experiment in water including active flow control

    NASA Astrophysics Data System (ADS)

    Beutel, T.; Sattler, S.; El Sayed, Y.; Schwerter, M.; Zander, M.; Büttgenbach, S.; Leester-Schädel, M.; Radespiel, R.; Sinapius, M.; Wierach, P.

    2014-07-01

    This paper describes the structural design of an active flow-control experiment. The aim of the experiment is to investigate the increase in efficiency of an internally blown Coanda flap using unsteady blowing. The system uses tailor-made microelectromechanical (MEMS) pressure sensors to determine the state of the oncoming flow and an actuated lip to regulate the mass flow and velocity of a stream near a wall over the internally blown flap. Sensors and actuators are integrated into a highly loaded system that is extremely compact. The sensors are connected to a bus system that feeds the data into a real-time control system. The piezoelectric actuators using the d 33 effect at a comparable low voltage of 120 V are integrated into a lip that controls the blowout slot height. The system is designed for closed-loop control that efficiently avoids flow separation on the Coanda flap. The setup is designed for water-tunnel experiments in order to reduce the free-stream velocity and the system’s control frequency by a factor of 10 compared with that in air. This paper outlines the function and verification of the system’s main components and their development.

  7. [Movement characteristics of Cyanobacteria under stress of water-lifting aeration].

    PubMed

    Sun, Xiu-Xiu; Cong, Hai-Bing; Gao, Zheng-Juan; Cui, Chao-Jie; Cao, Qian-Qian

    2014-05-01

    In order to study the impact of algae control mixing technology on the distribution characteristics and movement of Cyanobacteria, the floating and subsiding velocity of Cyanobacteria in Taihu Lake was measured under different conditions such as different illuminance, temperature and pressure. The Cyanobacteria showed strong propensity of floating under the illuminance from 1500 1x to 6000 1x. The Cyanobacteria particle with floating velocity of more than 0.8 cm.min-1 accounted for 58% under the illuminance of 1 500 1x. The floating velocity slowed down when the illuminance was lower than 1 500 1x or higher than 6 000 1x. In the temperature range of 8 to 25 Celsius degree, the Cyanobacteria floated and the floating velocity increased with temperature. The Cyanobacteria floated under the pressure of 0- 0. 1 MPa and the floating velocity slowed down as the pressure increased. Most Cyanobacteria were suspended in the water when the pressure reached 0. 2-0. 3 MPa and only a small part of the Cyanobacteria floated or settled. When the pressure reached 0. 4-0. 6 MPa, the Cyanobacteria notably settled and the subsiding velocity increased with the increase of pressure. The Cyanobacteria particles with subsiding velocity of more than 1.0 cm.min-1 accounted for 52.5% when the pressure was 0. 6 MPa. Gas vesicles bursted when the gas vesicles of the Cyanobacteria could not bear the external pressure. The buoyancy of the Cyanobacteria diminished until the floating force became smaller than its weight, causing the particles of the Cyanobacteria to settle. Under normal atmospheric pressure, the particle diameter was positively correlated to the floating velocity, while negatively correlated to the density. Under high pressure, the particle diameter was positively correlated to the subsiding velocity and the density.

  8. Detritiation of water using microporous hollow-fiber membranes

    SciTech Connect

    Kelso, R.C.; Ahmed, T.; Middlebrooks, E.J.

    1997-03-01

    A novel concept of tritium (HTO) removal with microporous hollow fiber membranes was evaluated in this study. Small-scale laboratory modules were constructed and tested to determine the mass transfer characteristics of the hollow fibers under varying system parameters. Tritiated water is pumped through the fiber lumen and air, saturated with water vapor, is pumped over the exterior of the fibers in a countercurrent mode. The high HTO concentration gradient encourages the HTO to diffuse across the porous membrane wall, and to transfer directly into the saturated air stream. A dimensionless mathematical correlation that predicts the tritium transfer coefficient across the membranes is presented for parallel flow modules. The measured overall mass transfer coefficients in the membrane module are two to three orders of magnitude greater than those of conventional bubble stripping. In additions, factors that influence the mass transfer performance of the membrane modules in practical applications are evaluated. The results indicate that very low concentrations of HTO can be separated from water using microporous hollow fiber membranes. 33 refs., 8 figs., 3 tabs.

  9. Solid-State Water Electrolysis with an Alkaline Membrane

    SciTech Connect

    Leng, YJ; Chen, G; Mendoza, AJ; Tighe, TB; Hickner, MA; Wang, CY

    2012-06-06

    We report high-performance, durable alkaline membrane water electrolysis in a solid-state cell. An anion exchange membrane (AEM) and catalyst layer ionomer for hydroxide ion conduction were used without the addition of liquid electrolyte. At 50 degrees C, an AEM electrolysis cell using iridium oxide as the anode catalyst and Pt black as the cathode catalyst exhibited a current density of 399 mA/cm(2) at 1.80 V. We found that the durability of the AEM-based electrolysis cell could be improved by incorporating a highly durable ionomer in the catalyst layer and optimizing the water feed configuration. We demonstrated an AEM-based electrolysis cell with a lifetime of > 535 h. These first-time results of water electrolysis in a solid-state membrane cell are promising for low-cost, scalable hydrogen production.

  10. Spacesuit Water Membrane Evaporator Development for Lunar Missions

    NASA Technical Reports Server (NTRS)

    Vogel, Matt R.; Peterson, Keith; Zapata, Felipe, III; Dillon, Paul; Trevino, Luis A.

    2008-01-01

    For future lunar extra-vehicular activities (EVA), one method under consideration for rejecting crew and electronics heat involves evaporating water through a hydrophobic, porous Teflon membrane. A Spacesuit Water Membrane Evaporator (SWME) prototype using the Teflon membrane was tested successfully by Ungar and Thomas (2001) with predicted performance matching test data well. The above referenced work laid the foundation for the design of the SWME development unit, which is being considered for service in the Constellation System Spacesuit Element (CSSE) Portable Life Support System (PLSS). Multiple PLSS SWME configurations were considered on the basis of thermal performance, mass, volume, and performance and manufacturing risk. All configurations were a variation of an alternating concentric water and vapor channel configuration or a stack of alternating rectangular water and vapor channels. Supporting thermal performance trades mapped maximum SWME heat rejection as a function of water channel thickness, vapor channel thickness, channel length, number of water channels, porosity of the membrane structural support, and backpressure valve throat area. Preliminary designs of each configuration were developed to determine total mass and volume as well as to understand manufacturing issues. Review of configurations led to the selection of a concentric annulus configuration that meets the requirements of 800 watts (W) of heat rejection. Detailed design of the SWME development unit will be followed by fabrication of a prototype test unit, with thermal testing expected to start in 2008.

  11. Water vapor diffusion membrane development. [for water recovery purposes onboard manned spacecraft

    NASA Technical Reports Server (NTRS)

    Tan, M. K.

    1974-01-01

    The phase separator component used as a membrane in the vapor diffusion process (VRD) for the recovery of potable water from urine on manned space missions of extended duration was investigated, with particular emphasis on cation-selective membranes because of their noted mechanical strength, superior resistance to acids, oxidants, and germicides, and their potential resistance to organic foulants. Two of the membranes were tested for 700 hours continuously, and were selected on the basis of criteria deemed important to an effective water reclamation system onboard spacecraft. The samples of urine were successfully processed by removing 93 percent of their water content in 70 hours using the selected membranes. Pretreatment with an acid-oxidant formulation improved product quality. Cation exchange membranes were shown to possess superior mechanical strength and chemical resistance, as compared to cellulosic membranes.

  12. Quantized Water Transport: Ideal Desalination through Graphyne-4 Membrane

    PubMed Central

    Zhu, Chongqin; Li, Hui; Zeng, Xiao Cheng; Wang, E. G.; Meng, Sheng

    2013-01-01

    Graphyne sheet exhibits promising potential for nanoscale desalination to achieve both high water permeability and salt rejection rate. Extensive molecular dynamics simulations on pore-size effects suggest that γ-graphyne-4, with 4 acetylene bonds between two adjacent phenyl rings, has the best performance with 100% salt rejection and an unprecedented water permeability, to our knowledge, of ~13 L/cm2/day/MPa, 3 orders of magnitude higher than prevailing commercial membranes based on reverse osmosis, and ~10 times higher than the state-of-the-art nanoporous graphene. Strikingly, water permeability across graphyne exhibits unexpected nonlinear dependence on the pore size. This counter-intuitive behavior is attributed to the quantized nature of water flow at the nanoscale, which has wide implications in controlling nanoscale water transport and designing highly effective membranes. PMID:24196437

  13. Confinement effects on water structure in membrane lyotropic phases.

    PubMed

    Guégan, Régis

    2011-06-15

    The change of the water structure in aqueous solutions of the tri-ethyleneglycol mono n-decyl ether (C(10)E(3)) was studied by micro Raman scattering. The results obtained on the O-H stretching band show that the behavior of the hydrogen bonding (H-bonds) water network can be used as a probe to follow the lamellar (L(α)) to sponge (L(3)) phase transition. In the lamellar phase, the stack of the surfactant molecules aggregated into a two-dimensional structure (membrane) acts as a soft confinement system for the H-bond water network of which the regular tetrahedral structure is perturbed. The change of the planar organization of the membranes to a highly disordered and infinite array of bilayers in the sponge phase amplifies the surface of contact between amphiphilic surfactant and water molecules which drives a strong disruption of the regular tetrahedral H-bonding water network.

  14. Removal of phenolic compounds in water by ultrafiltration membrane treatments.

    PubMed

    Acero, Juan L; Benítez, F Javier; Leal, Ana I; Real, Francisco J

    2005-01-01

    The ultrafiltration (UF) of aqueous solutions containing mixtures of three phenolic compounds (gallic acid, acetovanillone, and esculetin) was studied in a tangential UF laboratory system. These substances were selected as model pollutants present in the tannic fraction of the cork processing wastewaters. The two membranes used were a polyethersulfone membrane (Biomax5K) and a regenerated cellulose membrane (Ultracel5K), both with a molecular weight cut-off (MWCO) of 5000 Da. Previous experiments for the characterization of the membranes led to values for the water hydraulic permeability of 70.3 and 18.1 L/h x m2 x bar for the Biomax5K and Ultracel5K membranes, respectively. During the UF experiments, the permeate flow rate remained almost constant with processing time and the evolution of the pollutants concentrations varied depending on the nature of the membranes and the substances. The influence of the main operating variables (tansmembrane pressure and feed flow rate) on the permeate flux was established, and values for the apparent and intrinsic rejection coefficients were evaluated. Cork processing wastewater UF experiments were also conducted under similar operating conditions to those applied to the ultrapure water solutions. Removals of chemical oxygen demand, aromatic and tannic contents, and color were determined in these experiments, and the elimination of the three model compounds in the wastewater was also followed, with the evaluation of their apparent rejection coefficients.

  15. Advanced Water Removal via Membrane Solvent Extraction

    SciTech Connect

    2009-02-01

    This factsheet describes a research project that will focus on further concept and technology development and verification at the pilot scale of an MSE technology developed by 3M. The technology shows great promise to substantially decrease energy and water consumption in bioethanol production.

  16. Interactions of anesthetics with the membrane-water interface

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Cieplak, P.; Wilson, M. A.

    1996-01-01

    Although the potency of conventional anesthetics correlates with lipophilicity, an affinity to water also is essential. It was recently found that compounds with very low affinities to water do not produce anesthesia regardless of their lipophilicity. This finding implies that clinical anesthesia might arise because of interactions at molecular sites near the interface of neuronal membranes with the aqueous environment and, therefore, might require increased concentrations of anesthetic molecules at membrane interfaces. As an initial test of this hypothesis, we calculated in molecular dynamics simulations the free energy profiles for the transfer of anesthetic 1,1,2-trifluoroethane and nonanesthetic perfluoroethane across water-membrane and water-hexane interfaces. Consistent with the hypothesis, it was found that trifluoroethane, but not perfluoroethane, exhibits a free energy minimum and, therefore, increased concentrations at both interfaces. The transfer of trifluoroethane from water to the nonpolar hexane or interior of the membrane is accompanied by a considerable, solvent-induced shift in the conformational equilibrium around the C-C bond.

  17. Effectiveness of Water Desalination by Membrane Distillation Process

    PubMed Central

    Gryta, Marek

    2012-01-01

    The membrane distillation process constitutes one of the possibilities for a new method for water desalination. Four kinds of polypropylene membranes with different diameters of capillaries and pores, as well as wall thicknesses were used in studied. The morphology of the membrane used and the operating parameters significantly influenced process efficiency. It was found that the membranes with lower wall thickness and a larger pore size resulted in the higher yields. Increasing both feed flow rate and temperature increases the permeate flux and simultaneously the process efficiency. However, the use of higher flow rates also enhanced heat losses by conduction, which decreases the thermal efficiency. This efficiency also decreases when the salt concentration in the feed was enhanced. The influence of fouling on the process efficiency was considered. PMID:24958289

  18. Hybrid membrane operations in water desalination and industrial process rationalisation.

    PubMed

    Drioli, E; Di Profio, G; Curcio, E

    2005-01-01

    Membrane science and technology are recognized today as powerful tools in resolving some important global problems, and developing newer industrial processes, needed from the imperative of sustainable industrial growth. In seawater desalination, for resolving the dramatic increase of freshwater demand in many regions of the world, membrane unitary operations or the combination of some of them in integrated systems are already a real means for producing water from the sea, at lower costs and minimum environmental impact, with a very interesting prospective in particular for poor economy countries. However, membranes are used or are becoming used in some important industrial fields, for developing more efficient productive cycles, with reduced waste of raw-material, reducing the polluting charge by controlling byproduct generation, and reducing overall costs. In the present paper, other than for seawater desalination applications, some industrial applications where membrane technology has led already to match the goal of process intensification are discussed.

  19. Highly Water Resistant Anion Exchange Membrane for Fuel Cells.

    PubMed

    Yang, Zhengjin; Hou, Jianqiu; Wang, Xinyu; Wu, Liang; Xu, Tongwen

    2015-07-01

    For anion exchange membranes (AEMs), achieving efficient hydroxide conductivity without excessive hydrophilicity presents a challenge. Hence, new strategies for constructing mechanically strengthened and hydroxide conductive (especially at controlled humidity) membranes are critical for developing better AEMs. Macromolecular modification involving ylide chemistry (Wittig reaction) for the fabrication of novel AEMs with an interpenetrating polymer network structure is reported. The macromolecular modification is cost effective, facile, and based on a one-pot synthesis. AEM water uptake is reduced to 3.6 wt% and a high hydroxide conductivity (69.7 mS cm(-1) , 90 °C) is achieved simultaneously. More importantly, the membrane exhibits similar tensile strength (>35 MPa) and comparable flexibility in both dry and wet states. These AEMs could find further applications within anion exchange membrane fuel cells with low humidity or photoelectric assemblies.

  20. Membrane-based processes for sustainable power generation using water.

    PubMed

    Logan, Bruce E; Elimelech, Menachem

    2012-08-16

    Water has always been crucial to combustion and hydroelectric processes, but it could become the source of power in membrane-based systems that capture energy from natural and waste waters. Two processes are emerging as sustainable methods for capturing energy from sea water: pressure-retarded osmosis and reverse electrodialysis. These processes can also capture energy from waste heat by generating artificial salinity gradients using synthetic solutions, such as thermolytic salts. A further source of energy comes from organic matter in waste waters, which can be harnessed using microbial fuel-cell technology, allowing both wastewater treatment and power production.

  1. 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.

  2. Pilot study of a submerged membrane bioreactor for water reclamation.

    PubMed

    Qin, Jian-Jun; Oo, Maung Htun; Tao, Guihe; Kekre, Kiran A; Hashimoto, Tomotaka

    2009-01-01

    The objective of this pilot study was to investigate the operational conditions of newly developed MBR modules for water reclamation under tropical conditions. MUDC-620A MBR modules with hollow fibre PVDF membranes from Asahi-Kasei Chemicals were used in the study. The pilot plant with capacity of 50 m(3)/d was operated continuously (24-hour) over four months on site of Ulu Pandan Water Reclamation Plant (UPWRP) in Singapore. During the study, the MLSS in membrane tank was in the range of 6,840 approximately 9,540 mg/L. Filtration operation mode of the membrane unit was 9 minutes on production and 1 minute backwash. The air scouring for the membranes was 0.18-0.30 Nm(3)/h per m(2) membrane area all of the time. Trials on different membrane fluxes were conducted to obtain the sustainable flux. The analytical results showed that COD, TOC, T-N and NH4-N of the treated water were <30 mg/L, 5-7 mg/L, <13 mg/L and <0.1 mg/L, respectively, which met the requirement of Industrial Water for reuse. TMP was in the range of 12-40 kPa and could be recovered after cleaning with 2,000 mg/L sodium hypochlorite solution. Sludge clogging could be a challenge for long-term operation with the current module design. It was concluded that it was feasible for MUDC-620A MBR to operate at a net flux of 25-29 LMH (or 0.6-0.7 m/d) for treating the municipal wastewater at UPWRP.

  3. Use of ceregenins to create novel biofouling resistant water water-treatment membranes.

    SciTech Connect

    Kirk, Matthew F.; Jones, Howland D. T.; Feng, Yanshu; McGrath, Lucas K.; Altman, Susan Jeanne; Pollard, Jacob; Hibbs, Michael R.; Savage, Paul B.

    2010-05-01

    Scoping studies have demonstrated that ceragenins, when linked to water-treatment membranes have the potential to create biofouling resistant water-treatment membranes. Ceragenins are synthetically produced molecules that mimic antimicrobial peptides. Evidence includes measurements of CSA-13 prohibiting the growth of and killing planktonic Pseudomonas fluorescens. In addition, imaging of biofilms that were in contact of a ceragenin showed more dead cells relative to live cells than in a biofilm that had not been treated with a ceragenin. This work has demonstrated that ceragenins can be attached to polyamide reverse osmosis (RO) membranes, though work needs to improve the uniformity of the attachment. Finally, methods have been developed to use hyperspectral imaging with multivariate curve resolution to view ceragenins attached to the RO membrane. Future work will be conducted to better attach the ceragenin to the RO membranes and more completely test the biocidal effectiveness of the ceragenins on the membranes.

  4. The structure of graphene oxide membranes in liquid water, ethanol and water-ethanol mixtures.

    PubMed

    Talyzin, Alexandr V; Hausmaninger, Tomas; You, Shujie; Szabó, Tamás

    2014-01-07

    The structure of graphene oxide (GO) membranes was studied in situ in liquid solvents using synchrotron radiation X-ray diffraction in a broad temperature interval. GO membranes are hydrated by water similarly to precursor graphite oxide powders but intercalation of alcohols is strongly hindered, which explains why the GO membranes are permeated by water and not by ethanol. Insertion of ethanol into the membrane structure is limited to only one monolayer in the whole studied temperature range, in contrast to precursor graphite oxide powders, which are intercalated with up to two ethanol monolayers (Brodie) and four ethanol monolayers (Hummers). As a result, GO membranes demonstrate the absence of "negative thermal expansion" and phase transitions connected to insertion/de-insertion of alcohols upon temperature variations reported earlier for graphite oxide powders. Therefore, GO membranes are a distinct type of material with unique solvation properties compared to parent graphite oxides even if they are composed of the same graphene oxide flakes.

  5. Water hydrogen bonding in proton exchange and neutral polymer membranes

    NASA Astrophysics Data System (ADS)

    Smedley, Sarah Black

    Understanding the dynamics of water sorbed into polymer films is critical to reveal structure-property relationships in membranes for energy and water treatment applications, where membranes must interact with water to facilitate or inhibit the transport of ions. The chemical structure of the polymer has drastic effects on the transport properties of the membrane due to the morphological structure of the polymer and how water is interacting with the functional groups on the polymer backbone. Therefore studying the dynamics of water adsorbed into a membrane will give insight into how water-polymer interactions influence transport properties of the film. With a better understanding of how to design materials to have specific properties, we can accelerate development of smarter materials for both energy and water treatment applications to increase efficiency and create high-flux materials and processes. The goal of this dissertation is to investigate the water-polymer interactions in proton exchange and uncharged membranes and make correlations to their charge densities and transport properties. A linear Fourier Transform Infrared (FTIR) spectroscopic method for measuring the hydrogen bonding distribution of water sorbed in proton exchange membranes is described in this thesis. The information on the distribution of the microenvironments of water in an ionic polymer is critical to understanding the effects of different acidic groups on the proton conductivity of proton exchange membranes at low relative humidity. The OD stretch of dilute HOD in H2O is a single, well-defined vibrational band. When HOD in dilute H2O is sorbed into a proton exchange membrane, the OD stretch peak shifts based on the microenvironment that water encounters within the nanophase separated structure of the material. This peak shift is a signature of different hydrogen bonding populations within the membrane, which can be deconvoluted rigorously for dilute HOD in H 2O compared to only

  6. Membrane contactor/separator for an advanced ozone membrane reactor for treatment of recalcitrant organic pollutants in water

    SciTech Connect

    Chan, Wai Kit; Joueet, Justine; Heng, Samuel; Yeung, King Lun; Schrotter, Jean-Christophe

    2012-05-15

    An advanced ozone membrane reactor that synergistically combines membrane distributor for ozone gas, membrane contactor for pollutant adsorption and reaction, and membrane separator for clean water production is described. The membrane reactor represents an order of magnitude improvement over traditional semibatch reactor design and is capable of complete conversion of recalcitrant endocrine disrupting compounds (EDCs) in water at less than three minutes residence time. Coating the membrane contactor with alumina and hydrotalcite (Mg/Al=3) adsorbs and traps the organics in the reaction zone resulting in 30% increase of total organic carbon (TOC) removal. Large surface area coating that diffuses surface charges from adsorbed polar organic molecules is preferred as it reduces membrane polarization that is detrimental to separation. - Graphical abstract: Advanced ozone membrane reactor synergistically combines membrane distributor for ozone, membrane contactor for sorption and reaction and membrane separator for clean water production to achieve an order of magnitude enhancement in treatment performance compared to traditional ozone reactor. Highlights: Black-Right-Pointing-Pointer Novel reactor using membranes for ozone distributor, reaction contactor and water separator. Black-Right-Pointing-Pointer Designed to achieve an order of magnitude enhancement over traditional reactor. Black-Right-Pointing-Pointer Al{sub 2}O{sub 3} and hydrotalcite coatings capture and trap pollutants giving additional 30% TOC removal. Black-Right-Pointing-Pointer High surface area coating prevents polarization and improves membrane separation and life.

  7. Quantized Water Transport: Ideal Desalination through Graphyne-4 Membrane

    NASA Astrophysics Data System (ADS)

    Zhu, Chongqin; Li, Hui; Zeng, Xiao Cheng; Wang, E. G.; Meng, Sheng

    2014-03-01

    The shortage of clean and fresh water is one of most pervasive problems afflicting human being's life in the world. Desalination is one viable solution to produce clean water, since 98% of the available water in the form of salty water. Using molecular dynamics simulations, we demonstrate that graphyne sheet exhibits promising potential for nanoscale desalination to achieve both high water permeability and salt rejection rate. In addition, Graphyne sheets also are mechanically robust with high tolerance to deformation. Especially, γ-graphyne-4 has the best performance with 100% slat rejection and an unprecedented water permeability of ~ 13L/cm2/day/MPa. 3 orders of magnitude higher than prevailing commercial membranes based on reverse osmosis, and ~ 10 times higher than the state-of-the-art nanoporous graphene. Strikingly, water permeability across graphyne exhibits unexpected nonlinear dependence on the pore area. This counter-intuitive behavior is attributed to the quantized nature of water flow at the nanoscale, which has wide implications in controlling nanoscale water transport and designing highly effective membrane.

  8. Tailor-made polyamide membranes for water desalination.

    PubMed

    Choi, Wansuk; Gu, Joung-Eun; Park, Sang-Hee; Kim, Seyong; Bang, Joona; Baek, Kyung-Youl; Park, Byoungnam; Lee, Jong Suk; Chan, Edwin P; Lee, Jung-Hyun

    2015-01-27

    Independent control of the extrinsic and intrinsic properties of the polyamide (PA) selective layer is essential for designing thin-film composite (TFC) membranes with performance characteristics required for water purification applications besides seawater desalination. Current commercial TFC membranes fabricated via the well-established interfacial polymerization (IP) approach yield materials that are far from ideal because their layer thickness, surface roughness, polymer chemistry, and network structure cannot be separately tailored. In this work, tailor-made PA-based desalination membranes based on molecular layer-by-layer (mLbL) assembly are presented. The mLbL technique enables the construction of an ultrathin and highly cross-linked PA selective layer in a precisely and independently controlled manner. The mLbL-assembled TFC membranes exhibit significant enhancements in performance compared to their IP-assembled counterparts. A maximum sodium chloride rejection of 98.2% is achieved along with over 2.5 times higher water flux than the IP-assembled counterpart. More importantly, this work demonstrates the broad applicability of mLbL in fabricating a variety of PA-based TFC membranes with nanoscale control of the selective layer thickness and roughness independent of the specific polyamide chemistry.

  9. Membrane coagulation bioreactor (MCBR) for drinking water treatment.

    PubMed

    Tian, Jia-Yu; Liang, Heng; Li, Xing; You, Shi-jie; Tian, Sen; Li, Gui-bai

    2008-08-01

    In this paper, a novel submerged ultrafiltration (UF) membrane coagulation bioreactor (MCBR) process was evaluated for drinking water treatment at a hydraulic retention time (HRT) as short as 0.5h. The MCBR performed well not only in the elimination of particulates and microorganisms, but also in almost complete nitrification and phosphate removal. As compared to membrane bioreactor (MBR), MCBR achieved much higher removal efficiencies of organic matter in terms of total organic carbon (TOC), permanganate index (COD(Mn)), dissolved organic carbon (DOC) and UV absorbance at 254nm (UV(254)), as well as corresponding trihalomethanes formation potential (THMFP) and haloacetic acids formation potential (HAAFP), due to polyaluminium chloride (PACl) coagulation in the bioreactor. However, the reduction of biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) by MCBR was only 8.2% and 10.1% higher than that by MBR, indicating that biodegradable organic matter (BOM) was mainly removed through biodegradation. On the other hand, the trans-membrane pressure (TMP) of MCBR developed much lower than that of MBR, which implies that coagulation in the bioreactor could mitigate membrane fouling. It was also identified that the removal of organic matter was accomplished through the combination of three unit effects: rejection by UF, biodegradation by microorganism and coagulation by PACl. During filtration operation, a fouling layer was formed on the membranes surface of both MCBR and MBR, which functioned as a second membrane for further separating organic matter.

  10. Total facelift: forehead lift, midface lift, and neck lift.

    PubMed

    Park, Dong Man

    2015-03-01

    Patients with thick skin mainly exhibit the aging processes of sagging, whereas patients with thin skin develop wrinkles or volume loss. Asian skin is usually thicker than that of Westerners; and thus, the sagging of skin due to aging, rather than wrinkling, is the chief problem to be addressed in Asians. Asian skin is also relatively large in area and thick, implying that the weight of tissue to be lifted is considerably heavier. These factors account for the difficulties in performing a facelift in Asians. Facelifts can be divided into forehead lift, midface lift, and lower face lift. These can be performed individually or with 2-3 procedures combined.

  11. Total Facelift: Forehead Lift, Midface Lift, and Neck Lift

    PubMed Central

    2015-01-01

    Patients with thick skin mainly exhibit the aging processes of sagging, whereas patients with thin skin develop wrinkles or volume loss. Asian skin is usually thicker than that of Westerners; and thus, the sagging of skin due to aging, rather than wrinkling, is the chief problem to be addressed in Asians. Asian skin is also relatively large in area and thick, implying that the weight of tissue to be lifted is considerably heavier. These factors account for the difficulties in performing a facelift in Asians. Facelifts can be divided into forehead lift, midface lift, and lower face lift. These can be performed individually or with 2-3 procedures combined. PMID:25798381

  12. The Mars Dust Cycle: Investigating the Effects of Radiatively Active Water Ice Clouds on Surface Stresses and Dust Lifting Potential with the NASA Ames Mars General Circulation Model

    NASA Technical Reports Server (NTRS)

    Kahre, Melinda A.; Hollingsworth, Jeffery

    2012-01-01

    The dust cycle is a critically important component of Mars' current climate system. Dust is present in the atmosphere of Mars year-round but the dust loading varies with season in a generally repeatable manner. Dust has a significant influence on the thermal structure of the atmosphere and thus greatly affects atmospheric circulation. The dust cycle is the most difficult of the three climate cycles (CO2, water, and dust) to model realistically with general circulation models. Until recently, numerical modeling investigations of the dust cycle have typically not included the effects of couplings to the water cycle through cloud formation. In the Martian atmosphere, dust particles likely provide the seed nuclei for heterogeneous nucleation of water ice clouds. As ice coats atmospheric dust grains, the newly formed cloud particles exhibit different physical and radiative characteristics. Thus, the coupling between the dust and water cycles likely affects the distributions of dust, water vapor and water ice, and thus atmospheric heating and cooling and the resulting circulations. We use the NASA Ames Mars GCM to investigate the effects of radiatively active water ice clouds on surface stress and the potential for dust lifting. The model includes a state-of-the-art water ice cloud microphysics package and a radiative transfer scheme that accounts for the radiative effects of CO2 gas, dust, and water ice clouds. We focus on simulations that are radiatively forced by a prescribed dust map, and we compare simulations that do and do not include radiatively active clouds. Preliminary results suggest that the magnitude and spatial patterns of surface stress (and thus dust lifting potential) are substantial influenced by the radiative effects of water ice clouds.

  13. Bioinspired Bifunctional Membrane for Efficient Clean Water Generation.

    PubMed

    Liu, Yang; Lou, Jinwei; Ni, Mengtian; Song, Chengyi; Wu, Jianbo; Dasgupta, Neil P; Tao, Peng; Shang, Wen; Deng, Tao

    2016-01-13

    Solving the problems of water pollution and water shortage is an urgent need for the sustainable development of modern society. Different approaches, including distillation, filtration, and photocatalytic degradation, have been developed for the purification of contaminated water and the generation of clean water. In this study, we explored a new approach that uses solar light for both water purification and clean water generation. A bifunctional membrane consisting of a top layer of TiO2 nanoparticles (NPs), a middle layer of Au NPs, and a bottom layer of anodized aluminum oxide (AAO) was designed and fabricated through multiple filtration processes. Such a design enables both TiO2 NP-based photocatalytic function and Au NP-based solar-driven plasmonic evaporation. With the integration of these two functions into a single membrane, both the purification of contaminated water through photocatalytic degradation and the generation of clean water through evaporation were demonstrated using simulated solar illumination. Such a demonstration should also help open up a new strategy for maximizing solar energy conversion and utilization.

  14. Origin of anomalous water permeation through graphene oxide membrane.

    PubMed

    Boukhvalov, Danil W; Katsnelson, Mikhail I; Son, Young-Woo

    2013-08-14

    Water inside the low-dimensional carbon structures has been considered seriously owing to fundamental interest in its flow and structures as well as its practical impact. Recently, the anomalous perfect penetration of water through graphene oxide membrane was demonstrated although the membrane was impenetrable for other liquids and even gases. The unusual auxetic behavior of graphene oxide in the presence of water was also reported. Here, on the basis of first-principles calculations, we establish atomistic models for hybrid systems composed of water and graphene oxides revealing the anomalous water behavior inside the stacked graphene oxides. We show that formation of hexagonal ice bilayer in between the flakes as well as melting transition of ice at the edges of flakes are crucial to realize the perfect water permeation across the whole stacked structures. The distance between adjacent layers that can be controlled either by oxygen reduction process or pressure is shown to determine the water flow thus highlighting a unique water dynamics in randomly connected two-dimensional spaces.

  15. Application of Membrane Crystallization for Minerals’ Recovery from Produced Water

    PubMed Central

    Ali, Aamer; Quist-Jensen, Cejna Anna; Macedonio, Francesca; Drioli, Enrico

    2015-01-01

    Produced water represents the largest wastewater stream from oil and gas production. Generally, its high salinity level restricts the treatment options. Membrane crystallization (MCr) is an emerging membrane process with the capability to extract simultaneously fresh water and valuable components from various streams. In the current study, the potential of MCr for produced water treatment and salt recovery was demonstrated. The experiments were carried out in lab scale and semi-pilot scale. The effect of thermal and hydrodynamic conditions on process performance and crystal characteristics were explored. Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses confirmed that the recovered crystals are sodium chloride with very high purity (>99.9%), also indicated by the cubic structure observed by microscopy and SEM (scanning electron microscopy) analysis. It was demonstrated experimentally that at recovery factor of 37%, 16.4 kg NaCl per cubic meter of produced water can be recovered. Anti-scaling surface morphological features of membranes were also identified. In general, the study provides a new perspective of isolation of valuable constituents from produced water that, otherwise, is considered as a nuisance. PMID:26610581

  16. Barriers to superfast water transport in carbon nanotube membranes.

    PubMed

    Walther, Jens H; Ritos, Konstantinos; Cruz-Chu, Eduardo R; Megaridis, Constantine M; Koumoutsakos, Petros

    2013-05-08

    Carbon nanotube (CNT) membranes hold the promise of extraordinary fast water transport for applications such as energy efficient filtration and molecular level drug delivery. However, experiments and computations have reported flow rate enhancements over continuum hydrodynamics that contradict each other by orders of magnitude. We perform large scale molecular dynamics simulations emulating for the first time the micrometer thick CNTs membranes used in experiments. We find transport enhancement rates that are length dependent due to entrance and exit losses but asymptote to 2 orders of magnitude over the continuum predictions. These rates are far below those reported experimentally. The results suggest that the reported superfast water transport rates cannot be attributed to interactions of water with pristine CNTs alone.

  17. Swelling of ultrathin crosslinked polyamide water purification membranes

    NASA Astrophysics Data System (ADS)

    Chan, Edwin; Stafford, Christopher

    2013-03-01

    Polyamide (PA) ultrathin films represent the state-of-the-art nanofiltration and reverse osmosis membranes used in water desalination. The performance of these materials, such as permselectivity, is intimately linked with extent of swelling of the PA network. Thus, quantifying their swelling behavior would be a useful and simple route to understanding the specific network structural parameters that control membrane performance. In this work, we measure the swelling behavior of PA ultrathin films using X-ray reflectivity as a function of water hydration. By applying the Flory-Rehner theory used to describe the swelling behavior of polymer networks, we quantify the PA network properties including Flory interaction parameter and the monomer units between crosslinks. Finally, we demonstrate application of this measurement approach for characterizing the network properties of different types of PA ultrathin films relevant to water purification and discuss the relationship between network and transport properties. Materials Science and Engineering Division

  18. Desalting and water treatment membrane manual: A guide to membranes for municipal water treatment. Water treatment technology program report No. 1

    SciTech Connect

    Chapman-Wilbert, M.

    1993-09-01

    The Bureau of Reclamation prepared this manual to provide an overview of microfiltration, ultrafiltration, nanofiltration, reverse osmosis, and electrodialysis processes as they are used for water treatment. Membrane composition, the chemical processes, and the physical processes involved with each membrane type are described and compared. Because care and maintenance of water treatment membranes are vital to their performance and life expectancy, pretreatment, cleaning, and storage requirements are discussed in some detail. Options for concentrate disposal, also a problematic feature of membrane processes, are discussed. The culmination of this wealth of knowledge is an extensive comparison of water treatment membranes commercially available at this time. The tables cover physical characteristics, performance data, and operational tolerances.

  19. Membrane Technology for Produced Water in Lea County

    SciTech Connect

    Cecilia Nelson; Ashok Ghosh

    2011-06-30

    Southeastern New Mexico (SENM) is rich in mineral resources, including oil and gas. Produced water is a byproduct from oil and gas recovery operations. SENM generates approximately 400 million barrels per year of produced water with total dissolved solids (TDS) as high as ~ 200,000 ppm. Typically, produced water is disposed of by transporting it to injection wells or disposal ponds, costing around $1.2 billion per year with an estimated use of 0.3 million barrels of transportation fuel. New Mexico ranks first among U.S. states in potash production. Nationally, more than 85% of all potash produced comes from the Carlsbad potash district in SENM. Potash manufacturing processes use large quantities of water, including fresh water, for solution mining. If the produced water from oilfield operations can be treated and used economically in the potash industry, it will provide a beneficial use for the produced water as well as preserve valuable water resources in an area where fresh water is scarce. The goal of this current research was to develop a prototype desalination system that economically treats produced water from oil and/or natural gas operations for the beneficial use of industries located in southeastern New Mexico. Up until now, most water cleaning technologies have been developed for treating water with much lower quantities of TDS. Seawater with TDS of around 30,000 ppm is the highest concentration that has been seriously studied by researchers. Reverse osmosis (RO) technology is widely used; however the cost remains high due to high-energy consumption. Higher water fluxes and recoveries are possible with a properly designed Forward Osmosis (FO) process as large driving forces can be induced with properly chosen membranes and draw solution. Membrane fouling and breakdown is a frequent and costly problem that drives the cost of desalination very high. The technology developed by New Mexico Tech (NMT) researchers not only protects the membrane, but has also

  20. Transient bubble oscillations near an elastic membrane in water

    NASA Astrophysics Data System (ADS)

    Turangan, C. K.; Khoo, B. C.

    2015-12-01

    We present a study of transient oscillating bubble-elastic membrane interaction by means of an experiment and a numerical simulation to study the dynamics of bubble's inertial collapse near an elastic interface. The bubble is generated very close to a thin elastic membrane using an electric spark, and their interaction is observed using high speed photography. The high pressure and temperature plasma from the dielectric breakdown precedes the bubble formation. The bubble then expands and creates a dimple on the membrane. After reaching its maximum size, the bubble begins to collapse. The membrane retracts back, transmitting a perturbation on the bubble surface. The coupling between bubble contraction and this perturbation strengthens the collapse and leads to the formation of a mushroom-shaped bubble, bubble pinching and splitting. Towards the end of the collapse, the water inertia surrounding the bubble pulls the membrane upwards forming a relatively sharp conical hump. The dynamics of this interaction is well predicted by the boundary element method (BEM) simulation.

  1. Amyloid-carbon hybrid membranes for universal water purification

    NASA Astrophysics Data System (ADS)

    Bolisetty, Sreenath; Mezzenga, Raffaele

    2016-04-01

    Industrial development, energy production and mining have led to dramatically increased levels of environmental pollutants such as heavy metal ions, metal cyanides and nuclear waste. Current technologies for purifying contaminated waters are typically expensive and ion specific, and there is therefore a significant need for new approaches. Here, we report inexpensive hybrid membranes made from protein amyloid fibrils and activated porous carbon that can be used to remove heavy metal ions and radioactive waste from water. During filtration, the concentration of heavy metal ions drops by three to five orders of magnitude per passage and the process can be repeated numerous times. Notably, their efficiency remains unaltered when filtering several ions simultaneously. The performance of the membrane is enabled by the ability of the amyloids to selectively absorb heavy metal pollutants from solutions. We also show that our membranes can be used to recycle valuable heavy metal contaminants by thermally reducing ions trapped in saturated membranes, leading to the creation of elemental metal nanoparticles and films.

  2. Amyloid-carbon hybrid membranes for universal water purification.

    PubMed

    Bolisetty, Sreenath; Mezzenga, Raffaele

    2016-04-01

    Industrial development, energy production and mining have led to dramatically increased levels of environmental pollutants such as heavy metal ions, metal cyanides and nuclear waste. Current technologies for purifying contaminated waters are typically expensive and ion specific, and there is therefore a significant need for new approaches. Here, we report inexpensive hybrid membranes made from protein amyloid fibrils and activated porous carbon that can be used to remove heavy metal ions and radioactive waste from water. During filtration, the concentration of heavy metal ions drops by three to five orders of magnitude per passage and the process can be repeated numerous times. Notably, their efficiency remains unaltered when filtering several ions simultaneously. The performance of the membrane is enabled by the ability of the amyloids to selectively absorb heavy metal pollutants from solutions. We also show that our membranes can be used to recycle valuable heavy metal contaminants by thermally reducing ions trapped in saturated membranes, leading to the creation of elemental metal nanoparticles and films.

  3. Protic Salt Polymer Membranes: High-Temperature Water-Free Proton-Conducting Membranes

    SciTech Connect

    Gervasio, Dominic Francis

    2010-09-30

    This research on proton-containing (protic) salts directly addresses proton conduction at high and low temperatures. This research is unique, because no water is used for proton ionization nor conduction, so the properties of water do not limit proton fuel cells. A protic salt is all that is needed to give rise to ionized proton and to support proton mobility. A protic salt forms when proton transfers from an acid to a base. Protic salts were found to have proton conductivities that are as high as or higher than the best aqueous electrolytes at ambient pressures and comparable temperatures without or with water present. Proton conductivity of the protic salts occurs providing two conditions exist: i) the energy difference is about 0.8 eV between the protic-salt state versus the state in which the acid and base are separated and 2) the chemical constituents rotate freely. The physical state of these proton-conducting salts can be liquid, plastic crystal as well as solid organic and inorganic polymer membranes and their mixtures. Many acids and bases can be used to make a protic salt which allows tailoring of proton conductivity, as well as other properties that affect their use as electrolytes in fuel cells, such as, stability, adsorption on catalysts, environmental impact, etc. During this project, highly proton conducting (~ 0.1S/cm) protic salts were made that are stable under fuel-cell operating conditions and that gave highly efficient fuel cells. The high efficiency is attributed to an improved oxygen electroreduction process on Pt which was found to be virtually reversible in a number of liquid protic salts with low water activity (< 1% water). Solid flexible non-porous composite membranes, made from inorganic polymer (e.g., 10%indium 90%tin pyrophosphate, ITP) and organic polymer (e.g., polyvinyl pyridinium phosphate, PVPP), were found that give conductivity and fuel cell performances similar to phosphoric acid electrolyte with no need for hydration at

  4. Renewable Water: Direct Contact Membrane Distillation Coupled With Solar Ponds

    NASA Astrophysics Data System (ADS)

    Suarez, F. I.; Tyler, S. W.; Childress, A. E.

    2010-12-01

    The exponential population growth and the accelerated increase in the standard of living have increased significantly the global consumption of two precious resources: water and energy. These resources are intrinsically linked and are required to allow a high quality of human life. With sufficient energy, water may be harvested from aquifers, treated for potable reuse, or desalinated from brackish and seawater supplies. Even though the costs of desalination have declined significantly, traditional desalination systems still require large quantities of energy, typically from fossil fuels that will not allow these systems to produce water in a sustainable way. Recent advances in direct contact membrane distillation can take advantage of low-quality or renewable heat to desalinate brackish water, seawater or wastewater. Direct contact membrane distillation operates at low pressures and can use small temperature differences between the feed and permeate water to achieve a significant freshwater production. Therefore, a much broader selection of energy sources can be considered to drive thermal desalination. A promising method for providing renewable source of heat for direct contact membrane distillation is a solar pond, which is an artificially stratified water body that captures solar radiation and stores it as thermal energy at the bottom of the pond. In this work, a direct contact membrane distillation/solar pond coupled system is modeled and tested using a laboratory-scale system. Freshwater production rates on the order of 2 L day-1 per m2 of solar pond (1 L hr-1 per m2 of membrane area) can easily be achieved with minimal operating costs and under low pressures. While these rates are modest, they are six times larger than those produced by other solar pond-powered desalination systems - and they are likely to be increased if heat losses in the laboratory-scale system are reduced. Even more, this system operates at much lower costs than traditional desalination

  5. Variable Lifting Index (VLI)

    PubMed Central

    Waters, Thomas; Occhipinti, Enrico; Colombini, Daniela; Alvarez-Casado, Enrique; Fox, Robert

    2015-01-01

    Objective: We seek to develop a new approach for analyzing the physical demands of highly variable lifting tasks through an adaptation of the Revised NIOSH (National Institute for Occupational Safety and Health) Lifting Equation (RNLE) into a Variable Lifting Index (VLI). Background: There are many jobs that contain individual lifts that vary from lift to lift due to the task requirements. The NIOSH Lifting Equation is not suitable in its present form to analyze variable lifting tasks. Method: In extending the prior work on the VLI, two procedures are presented to allow users to analyze variable lifting tasks. One approach involves the sampling of lifting tasks performed by a worker over a shift and the calculation of the Frequency Independent Lift Index (FILI) for each sampled lift and the aggregation of the FILI values into six categories. The Composite Lift Index (CLI) equation is used with lifting index (LI) category frequency data to calculate the VLI. The second approach employs a detailed systematic collection of lifting task data from production and/or organizational sources. The data are organized into simplified task parameter categories and further aggregated into six FILI categories, which also use the CLI equation to calculate the VLI. Results: The two procedures will allow practitioners to systematically employ the VLI method to a variety of work situations where highly variable lifting tasks are performed. Conclusions: The scientific basis for the VLI procedure is similar to that for the CLI originally presented by NIOSH; however, the VLI method remains to be validated. Application: The VLI method allows an analyst to assess highly variable manual lifting jobs in which the task characteristics vary from lift to lift during a shift. PMID:26646300

  6. Long Duration Testing of a Spacesuit Water Membrane Evaporator Prototype

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Makinen, Janice; Cox, Marlon; Watts, Carly; Campbell, Colin; Vogel, Matthew; Colunga, Aaron

    2011-01-01

    The Spacesuit Water Membrane Evaporator (SWME) is a heat-rejection device that is being developed to perform thermal control for advanced spacesuits. Cooling is achieved by circulating water from the liquid cooling garment (LCG) through hollow fibers (HoFi?s), which are small hydrophobic tubes. Liquid water remains within the hydrophobic tubes, but water vapor is exhausted to space, thereby removing heat. A SWME test article was tested over the course of a year, for a total of 1200 cumulative hours. In order to evaluate SWME tolerance to contamination due to constituents caused by distillation processes, these constituents were allowed to accumulate in the water as evaporation occurred. A test article was tested over the course of a year for a total of 1200 cumulative hours. The heat rejection performance of the SWME degraded significantly--below 700 W, attributable to the accumulation of rust in the circulating loop and biofilm growth. Bubble elimination capability, a feature that was previously proven with SWME, was compromised during the test, most likely due to loss of hydrophobic properties of the hollow fibers. The utilization of water for heat rejection was shown not to be dependent on test article, life cycle, heat rejection rate, or freezing of the membranes.

  7. Long Duration Testing of a Spacesuit Water Membrane Evaporator Prototype

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Makinen, Janice; Cox, Marlon; Watts, Carly; Campbell, Colin; Vogel, Matthew; Colunga, Aaron; Conger, Bruce

    2012-01-01

    The Spacesuit Water Membrane Evaporator (SWME) is a heat-rejection device that is being developed to perform thermal control for advanced spacesuits. Cooling is achieved by circulating water from the liquid cooling garment (LCG) through hollow fibers (HoFi s), which are small hydrophobic tubes. Liquid water remains within the hydrophobic tubes, but water vapor is exhausted to space, thereby removing heat. A SWME test article was tested over the course of a year, for a total of 600 cumulative hours. In order to evaluate SWME tolerance to contamination due to constituents caused by distillation processes, these constituents were allowed to accumulate in the water as evaporation occurred. A test article was tested over the course of a year for a total of 600 cumulative hours. The heat rejection performance of the SWME degraded significantly--below 700 W, attributable to the accumulation of rust in the circulating loop and biofilm growth. Bubble elimination capability, a feature that was previously proven with SWME, was compromised during the test, most likely due to loss of hydrophobic properties of the hollow fibers. The utilization of water for heat rejection was shown not to be dependent on test article, life cycle, heat rejection rate, or freezing of the membranes.

  8. Membrane Bioprocesses for Pharmaceutical Micropollutant Removal from Waters

    PubMed Central

    de Cazes, Matthias; Abejón, Ricardo; Belleville, Marie-Pierre; Sanchez-Marcano, José

    2014-01-01

    The purpose of this review work is to give an overview of the research reported on bioprocesses for the treatment of domestic or industrial wastewaters (WW) containing pharmaceuticals. Conventional WW treatment technologies are not efficient enough to completely remove all pharmaceuticals from water. Indeed, these compounds are becoming an actual public health problem, because they are more and more present in underground and even in potable waters. Different types of bioprocesses are described in this work: from classical activated sludge systems, which allow the depletion of pharmaceuticals by bio-degradation and adsorption, to enzymatic reactions, which are more focused on the treatment of WW containing a relatively high content of pharmaceuticals and less organic carbon pollution than classical WW. Different aspects concerning the advantages of membrane bioreactors for pharmaceuticals removal are discussed, as well as the more recent studies on enzymatic membrane reactors to the depletion of these recalcitrant compounds. PMID:25295629

  9. Water Permeability of Chlorella Cell Membranes by Nuclear Magnetic Resonance

    PubMed Central

    Stout, Darryl G.; Steponkus, Peter L.; Bustard, Larry D.; Cotts, Robert M.

    1978-01-01

    Measurement by two nuclear magnetic resonance (NMR) techniques of the mean residence time τa of water molecules inside Chlorella vulgaris (Beijerinck) var. “viridis” (Chodot) is reported. The first is the Conlon and Outhred (1972 Biochim Biophys Acta 288: 354-361) technique in which extracellular water is doped with paramagnetic Mn2+ ions. Some complications in application of this technique are identified as being caused by the affinity of Chlorella cell walls for Mn2+ ions which shortens the NMR relaxation times of intra- and extracellular water. The second is based upon observations of effects of diffusion on the spin echo of intra- and extracellular water. Echo attenuation of intracellular water is distinguished from that of extracellular water by the extent to which diffusive motion is restricted. Intracellular water, being restricted to the cell volume, suffers less echo attenuation. From the dependence of echo amplitude upon gradient strength at several values of echo time, the mean residence time of intracellular water can be determined. From the mean residence time of intracellular water, the diffusional water permeability coefficient of the Chlorella membrane is calculated to be 2.1 ± 0.4 × 10−3 cm sec−1. PMID:16660456

  10. Interferometric tomography of fuel cells for monitoring membrane water content.

    PubMed

    Waller, Laura; Kim, Jungik; Shao-Horn, Yang; Barbastathis, George

    2009-08-17

    We have developed a system that uses two 1D interferometric phase projections for reconstruction of 2D water content changes over time in situ in a proton exchange membrane (PEM) fuel cell system. By modifying the filtered backprojection tomographic algorithm, we are able to incorporate a priori information about the object distribution into a fast reconstruction algorithm which is suitable for real-time monitoring.

  11. New and expected developments in artificial lift

    SciTech Connect

    Lea, J.F.; Winkler, H.W.

    1994-12-31

    Artificial lift is a broad subject. This paper discusses some of the new developments in the major areas of artificial lift. These are (1) beam lift, (2) electrical submersible pumping, (3) gas lift, (4) hydraulic pumping and (5) miscellaneous topics. The beam lift discussion concerns a new rod material, downhole measurements for rod loading, unit design and some miscellaneous topics. The ESP (Electrical Submersible Pump) section includes a discussion on solids handling, downhole sensor technology, new motor temperature limitations, motor efficiency, and other topics. The gas lift discussion includes mention of coiled tubing with gas lift valves internal, a surface controlled gas lift valve concept, and gas lift valve testing and modeling. Hydraulic pumping is used in many locations with deep pay and fairly small production rates. New hydraulic developments include a wider availability of power fluid pumps other than positive displacement pumps, and small jet pumps specifically designed for de-watering gas wells. Some miscellaneous developments include an insertable PC (progressing cavity) pump and improved plunger lift algorithms and equipment.

  12. Rotating carbon nanotube membrane filter for water desalination

    NASA Astrophysics Data System (ADS)

    Tu, Qingsong; Yang, Qiang; Wang, Hualin; Li, Shaofan

    2016-05-01

    We have designed a porous nanofluidic desalination device, a rotating carbon nanotube membrane filter (RCNT-MF), for the reverse osmosis desalination that can turn salt water into fresh water. The concept as well as design strategy of RCNT-MF is modeled, and demonstrated by using molecular dynamics simulation. It has been shown that the RCNT-MF device may significantly improve desalination efficiency by combining the centrifugal force propelled reverse osmosis process and the porous CNT-based fine scale selective separation technology.

  13. Rotating carbon nanotube membrane filter for water desalination.

    PubMed

    Tu, Qingsong; Yang, Qiang; Wang, Hualin; Li, Shaofan

    2016-05-18

    We have designed a porous nanofluidic desalination device, a rotating carbon nanotube membrane filter (RCNT-MF), for the reverse osmosis desalination that can turn salt water into fresh water. The concept as well as design strategy of RCNT-MF is modeled, and demonstrated by using molecular dynamics simulation. It has been shown that the RCNT-MF device may significantly improve desalination efficiency by combining the centrifugal force propelled reverse osmosis process and the porous CNT-based fine scale selective separation technology.

  14. Rotating carbon nanotube membrane filter for water desalination

    PubMed Central

    Tu, Qingsong; Yang, Qiang; Wang, Hualin; Li, Shaofan

    2016-01-01

    We have designed a porous nanofluidic desalination device, a rotating carbon nanotube membrane filter (RCNT-MF), for the reverse osmosis desalination that can turn salt water into fresh water. The concept as well as design strategy of RCNT-MF is modeled, and demonstrated by using molecular dynamics simulation. It has been shown that the RCNT-MF device may significantly improve desalination efficiency by combining the centrifugal force propelled reverse osmosis process and the porous CNT-based fine scale selective separation technology. PMID:27188982

  15. Membrane contactor/separator for an advanced ozone membrane reactor for treatment of recalcitrant organic pollutants in water

    NASA Astrophysics Data System (ADS)

    Kit Chan, Wai; Jouët, Justine; Heng, Samuel; Lun Yeung, King; Schrotter, Jean-Christophe

    2012-05-01

    An advanced ozone membrane reactor that synergistically combines membrane distributor for ozone gas, membrane contactor for pollutant adsorption and reaction, and membrane separator for clean water production is described. The membrane reactor represents an order of magnitude improvement over traditional semibatch reactor design and is capable of complete conversion of recalcitrant endocrine disrupting compounds (EDCs) in water at less than three minutes residence time. Coating the membrane contactor with alumina and hydrotalcite (Mg/Al=3) adsorbs and traps the organics in the reaction zone resulting in 30% increase of total organic carbon (TOC) removal. Large surface area coating that diffuses surface charges from adsorbed polar organic molecules is preferred as it reduces membrane polarization that is detrimental to separation.

  16. Lift truck safety review

    SciTech Connect

    Cadwallader, L.C.

    1997-03-01

    This report presents safety information about powered industrial trucks. The basic lift truck, the counterbalanced sit down rider truck, is the primary focus of the report. Lift truck engineering is briefly described, then a hazard analysis is performed on the lift truck. Case histories and accident statistics are also given. Rules and regulations about lift trucks, such as the US Occupational Safety an Health Administration laws and the Underwriter`s Laboratories standards, are discussed. Safety issues with lift trucks are reviewed, and lift truck safety and reliability are discussed. Some quantitative reliability values are given.

  17. Measurement of water content in polymer electrolyte membranes using high resolution neutron imaging

    SciTech Connect

    Spernjak, Dusan; Mukundan, Rangachary; Borup, Rodney L; Davey, John; Mukherjee, Partha P; Hussey, Daniel S; Jacobson, David

    2010-01-01

    Sufficient water content within a polymer electrolyte membrane (PEM) is necessary for adequate ionic conductivity. Membrane hydration is therefore a fundamental requirement for fuel cell operation. The hydration state of the membrane affects the water transport within, as both the diffusion coefficient and electro-osmotic drag depend on the water content. Membrane's water uptake is conventionally measured ex situ by weighing free-swelling samples equilibrated at controlled water activity. In the present study, water profiles in Nafion{reg_sign} membranes were measured using the high-resolution neutron imaging. The state-of-the-art, 10 {micro}m resolution neutron detector is capable of resolving water distributions across N1120, N1110 and N117 membranes. It provides a means to measure the water uptake and transport properties of fuel cell membranes in situ.

  18. Molecular, Cellular and Pharmaceutical Aspects of bone grafting materials and membranes during maxillary sinus-lift procedures. Part 2: detailed characteristics of the materials.

    PubMed

    Iezzi, Giovanna; Piatelli, Adriano; Giuliani, Alessandra; Mangano, Carlo; Barone, Antonio; Manzon, Licia; Degidi, Marco; Scarano, Antonio; Filippone, Antonella; Perrotti, Vittoria

    2016-12-01

    Various grafts or combination of bone substitute materials have been used in sinus lift procedures. Currently, ongoing developments in several disciplines, from molecular biology and chemistry to computer science and engineering, have contributed to the understanding of biological processes leading to bone healing after the use of bone substitute materials (BSBs) and therefore of the behavior of BSBs. The understanding of the properties of each graft enables individual treatment concepts and therefore allows shift from a simple replacement material to the modern concept of an individually created composite biomaterial. Indeed, the choice of the best BSB still remains crucial for success in maxillary sinus augmentation procedures. The present article provides an overview of most of the materials currently available for sinus lift, with a specific focus on their histological, molecular, cellular and pharmaceutical aspects.

  19. Testing of Commercial Hollow Fiber Membranes for Space Suit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Trevino, Luis; Tsioulos, Gus; Hanford, Anthony

    2009-01-01

    Three commercial-off-the-shelf (COTS) hollow fiber (HoFi) membrane evaporators, modified for low pressure, were tested in a vacuum chamber at pressures below 33 pascals as potential space suit water membrane evaporator (SWME) heat rejection technologies. Water quality was controlled in a series of 25 tests, first simulating potable water reclaimed from waste water and then changing periodically to simulate the ever concentrating make-up of the circulating coolant over that is predicted over the course of 100 EVAs. Two of the systems, comprised of non-porous tubes with hydrophilic molecular channels as the water vapor transport mechanism, were severely impacted by the increasing concentrations of cations in the water. One of the systems, based on hydrophobic porous polypropylene tubes was not affected by the degrading water quality, or the presence of microbes. The polypropylene system, called SWME 1, was selected for further testing. An inverse flow configuration was also tested with SWME 1, with vacuum exposure on the inside of the tubes, provided only 20% of the performance of the standard configuration. SWME 1 was also modified to block 50% and 90% of the central tube layers, and tested to investigate performance efficiency. Performance curves were also developed in back-pressure regulation tests, and revealed important design considerations arising from the fully closed valve. SWME 1 was shown to be insensitive to air bubbles injected into the coolant loop. Development and testing of a full-scale prototype based on this technology and these test results is in progress.

  20. Thermal properties of phosphoric acid-doped polybenzimidazole membranes in water and methanol-water mixtures

    NASA Astrophysics Data System (ADS)

    Nores-Pondal, Federico J.; Buera, M. Pilar; Corti, Horacio R.

    The thermal properties of phosphoric acid-doped poly[2-2‧-(m-phenylene)-5-5‧ bi-benzimidazole] (PBI) and poly[2,5-benzimidazole] (ABPBI) membranes, ionomeric materials with promising properties to be used as electrolytes in direct methanol and in high temperature polymer electrolyte membrane (PEM) fuel cells, were studied by means of differential scanning calorimetry (DSC) technique in the temperature range from -145 °C to 200 °C. The DSC scans of samples equilibrated in water at different relative humidities (RH) and in liquid water-methanol mixtures were analyzed in relation to glass transition, water crystallization/melting and solvent desorption in different temperature regions. The thermal relaxation observed in the very low temperature region could be ascribed to the glass transition of the H 3PO 4-H 2O mixture confined in the polymeric matrix. After cooling the samples up to -145 °C, frozen water was detected in PBI and ABPBI at different RH, although at 100% RH less amount of water had crystallized than that observed in Nafion membranes under the same conditions. Even more important is the fact that the freezing degree of water is much lower in ABPBI membranes equilibrated in liquid water-methanol mixtures than that observed for PBI and, in a previous study, for Nafion. Thus, apart from other well known properties, acid-doped ABPBI emerges as an excellent ionomer for applications in direct methanol fuel cells working in cold environments.

  1. A novel membrane device for the removal of water vapor and water droplets from air

    NASA Technical Reports Server (NTRS)

    Ray, Rod; Newbold, David D.; Mccray, Scott B.; Friesen, Dwayne T.; Kliss, Mark

    1992-01-01

    One of the key challenges facing NASA engineers is the development of systems for separating liquids and gases in microgravity environments. In this paper, a novel membrane-based phase separator is described. This device, known as a water recovery heat exchanger (WRHEX), overcomes the inherent deficiencies of current phase-separation technology. Specifically, the WRHEX cools and removes water vapor or water droplets from feed-air streams without the use of a vacuum or centrifugal force. As is shown in this paper, only a low-power air blower and a small stream of recirculated cool water is required for WRHEX operation. This paper presents the results of tests using this novel membrane device over a wide range of operating conditions. The data show that the WRHEX produces a dry air stream containing no entrained or liquid water - even when the feed air contains water droplets or mist. An analysis of the operation of the WRHEX is presented.

  2. Nonequilibrium molecular dynamics simulation of pressure-driven water transport through modified CNT membranes.

    PubMed

    Wang, Luying; Dumont, Randall S; Dickson, James M

    2013-03-28

    Nonequilibrium molecular dynamics (NEMD) simulations are presented to investigate the effect of water-membrane interactions on the transport properties of pressure-driven water flow passing through carbon nanotube (CNT) membranes. The CNT membrane is modified with different physical properties to alter the van der Waals interactions or the electrostatic interactions between water molecules and the CNT membranes. The unmodified and modified CNT membranes are models of simplified nanofiltration (NF) membranes at operating conditions consistent with real NF systems. All NEMD simulations are run with constant pressure difference (8.0 MPa) temperature (300 K), constant pore size (0.643 nm radius for CNT (12, 12)), and membrane thickness (6.0 nm). The water flow rate, density, and velocity (in flow direction) distributions are obtained by analyzing the NEMD simulation results to compare transport through the modified and unmodified CNT membranes. The pressure-driven water flow through CNT membranes is from 11 to 21 times faster than predicted by the Navier-Stokes equations. For water passing through the modified membrane with stronger van der Waals or electrostatic interactions, the fast flow is reduced giving lower flow rates and velocities. These investigations show the effect of water-CNT membrane interactions on water transport under NF operating conditions. This work can help provide and improve the understanding of how these membrane characteristics affect membrane performance for real NF processes.

  3. Nonequilibrium molecular dynamics simulation of pressure-driven water transport through modified CNT membranes

    NASA Astrophysics Data System (ADS)

    Wang, Luying; Dumont, Randall S.; Dickson, James M.

    2013-03-01

    Nonequilibrium molecular dynamics (NEMD) simulations are presented to investigate the effect of water-membrane interactions on the transport properties of pressure-driven water flow passing through carbon nanotube (CNT) membranes. The CNT membrane is modified with different physical properties to alter the van der Waals interactions or the electrostatic interactions between water molecules and the CNT membranes. The unmodified and modified CNT membranes are models of simplified nanofiltration (NF) membranes at operating conditions consistent with real NF systems. All NEMD simulations are run with constant pressure difference (8.0 MPa) temperature (300 K), constant pore size (0.643 nm radius for CNT (12, 12)), and membrane thickness (6.0 nm). The water flow rate, density, and velocity (in flow direction) distributions are obtained by analyzing the NEMD simulation results to compare transport through the modified and unmodified CNT membranes. The pressure-driven water flow through CNT membranes is from 11 to 21 times faster than predicted by the Navier-Stokes equations. For water passing through the modified membrane with stronger van der Waals or electrostatic interactions, the fast flow is reduced giving lower flow rates and velocities. These investigations show the effect of water-CNT membrane interactions on water transport under NF operating conditions. This work can help provide and improve the understanding of how these membrane characteristics affect membrane performance for real NF processes.

  4. Integrated Water Gas Shift Membrane Reactors Utilizing Novel, Non Precious Metal Mixed Matrix Membrane

    SciTech Connect

    Ferraris, John

    2013-09-30

    Nanoparticles of zeolitic imidazolate frameworks and other related hybrid materials were prepared by modifying published synthesis procedures by introducing bases, changing stoichiometric ratios, or adjusting reaction conditions. These materials were stable at temperatures >300 °C and were compatible with the polymer matrices used to prepare mixed- matrix membranes (MMMs). MMMs tested at 300 °C exhibited a >30 fold increase in permeability, compared to those measured at 35 °C, while maintaining H{sub 2}/CO{sub 2} selectivity. Measurements at high pressure (up to 30 atm) and high temperature (up to 300 °C) resulted in an increase in gas flux across the membrane with retention of selectivity. No variations in permeability were observed at high pressures at either 35 or 300 °C. CO{sub 2}-induced plasticization was not observed for Matrimid®, VTEC, and PBI polymers or their MMMs at 30 atm and 300 °C. Membrane surface modification by cross-linking with ethanol diamine resulted in an increase in H{sub 2}/CO{sub 2} selectivity at 35 °C. Spectrometric analysis showed that the cross-linking was effective to temperatures <150 °C. At higher temperatures, the cross-linked membranes exhibit a H{sub 2}/CO{sub 2} selectivity similar to the uncross-linked polymer. Performance of the polybenzimidazole (PBI) hollow fibers prepared at Santa Fe Science and Technology (SFST, Inc.) showed increased flux o to a flat PBI membrane. A water-gas shift reactor has been built and currently being optimized for testing under DOE conditions.

  5. Highly hydrophilic poly(vinylidene fluoride)/meso-titania hybrid mesoporous membrane for photocatalytic membrane reactor in water

    NASA Astrophysics Data System (ADS)

    Wang, Meng; Yang, Guang; Jin, Peng; Tang, Hao; Wang, Huanhuan; Chen, Yong

    2016-01-01

    The high hydrophobicity of poly(vinylidene fluoride) (PVDF) membrane remains an obstacle to be applied in some purification processes of water or wastewater. Herein, a highly hydrophilic hybrid mesoporous titania membrane composed of mesoporous anatase titania (meso-TiO2) materials inside the three-dimensional (3D) macropores of PVDF membrane was successfully prepared by using the dual-templated synthesis method combined with solvent extraction and applied as the photocatalytic membrane reactor for the photodegredation of organic dye in water. The structure and the properties of as-prepared hybrid membranes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption–desorption and contact angle measurements. It was found that the hydrophilicity of PVDF membrane can be significantly improved by filling mesoporous TiO2 inside the 3D macropores of PVDF membrane. Moreover, such a PVDF/meso-TiO2 hybrid membrane exhibits promising photocatalytic degradation of dye in water due to the existence of mesoporous anatase TiO2 materials inside PVDF membrane. This study provides a new strategy to simultaneously introduce hydrophilicity and some desirable properties into PVDF and other hydrophobic membranes.

  6. Highly hydrophilic poly(vinylidene fluoride)/meso-titania hybrid mesoporous membrane for photocatalytic membrane reactor in water

    PubMed Central

    Wang, Meng; Yang, Guang; Jin, Peng; Tang, Hao; Wang, Huanhuan; Chen, Yong

    2016-01-01

    The high hydrophobicity of poly(vinylidene fluoride) (PVDF) membrane remains an obstacle to be applied in some purification processes of water or wastewater. Herein, a highly hydrophilic hybrid mesoporous titania membrane composed of mesoporous anatase titania (meso-TiO2) materials inside the three-dimensional (3D) macropores of PVDF membrane was successfully prepared by using the dual-templated synthesis method combined with solvent extraction and applied as the photocatalytic membrane reactor for the photodegredation of organic dye in water. The structure and the properties of as-prepared hybrid membranes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption–desorption and contact angle measurements. It was found that the hydrophilicity of PVDF membrane can be significantly improved by filling mesoporous TiO2 inside the 3D macropores of PVDF membrane. Moreover, such a PVDF/meso-TiO2 hybrid membrane exhibits promising photocatalytic degradation of dye in water due to the existence of mesoporous anatase TiO2 materials inside PVDF membrane. This study provides a new strategy to simultaneously introduce hydrophilicity and some desirable properties into PVDF and other hydrophobic membranes. PMID:26754440

  7. Advanced Membrane Filtration Technology for Cost Effective Recovery of Fresh Water from Oil & Gas Produced Brine

    SciTech Connect

    David B. Burnett

    2004-09-29

    Produced water is a major waste generated at the oil and natural gas wells in the state of Texas. This water could be a possible source of new fresh water to meet the growing demands of the state after treatment and purification. Treatment of brine generated in oil fields or produced water with an ultrafiltration membranes were the subject of this thesis. The characterization of ultrafiltration membranes for oil and suspended solids removal of produced water, coupled with the reverse osmosis (RO) desalination of brine were studied on lab size membrane testing equipment and a field size testing unit to test whether a viable membrane system could be used to treat produced water. Oil and suspended solids were evaluated using turbidity and oil in water measurements taken periodically. The research considered the effect of pressure and flow rate on membrane performance of produced water treatment of three commercially available membranes for oily water. The study also analyzed the flux through the membrane and any effect it had on membrane performance. The research showed that an ultrafiltration membrane provided turbidity removal of over 99% and oil removal of 78% for the produced water samples. The results indicated that the ultrafiltration membranes would be asset as one of the first steps in purifying the water. Further results on selected RO membranes showed that salt rejection of greater than 97% could be achieved with satisfactory flux and at reasonable operating cost.

  8. Development of Novel Water-Gas Shift Membrane Reactor

    SciTech Connect

    Ho, W. S. Winston

    2004-12-29

    This report summarizes the objectives, technical barrier, approach, and accomplishments for the development of a novel water-gas-shift (WGS) membrane reactor for hydrogen enhancement and CO reduction. We have synthesized novel CO{sub 2}-selective membranes with high CO{sub 2} permeabilities and high CO{sub 2}/H{sub 2} and CO{sub 2}/CO selectivities by incorporating amino groups in polymer networks. We have also developed a one-dimensional non-isothermal model for the countercurrent WGS membrane reactor. The modeling results have shown that H{sub 2} enhancement (>99.6% H{sub 2} for the steam reforming of methane and >54% H{sub 2} for the autothermal reforming of gasoline with air on a dry basis) via CO{sub 2} removal and CO reduction to 10 ppm or lower are achievable for synthesis gases. With this model, we have elucidated the effects of system parameters, including CO{sub 2}/H{sub 2} selectivity, CO{sub 2} permeability, sweep/feed flow rate ratio, feed temperature, sweep temperature, feed pressure, catalyst activity, and feed CO concentration, on the membrane reactor performance. Based on the modeling study using the membrane data obtained, we showed the feasibility of achieving H{sub 2} enhancement via CO{sub 2} removal, CO reduction to {le} 10 ppm, and high H{sub 2} recovery. Using the membrane synthesized, we have obtained <10 ppm CO in the H{sub 2} product in WGS membrane reactor experiments. From the experiments, we verified the model developed. In addition, we removed CO{sub 2} from a syngas containing 17% CO{sub 2} to about 30 ppm. The CO{sub 2} removal data agreed well with the model developed. The syngas with about 0.1% CO{sub 2} and 1% CO was processed to convert the carbon oxides to methane via methanation to obtain <5 ppm CO in the H{sub 2} product.

  9. Industrial membrane processes in the treatment of process waters and liquors.

    PubMed

    Mänttäri, M; Kallioinen, M; Pihlajamäki, A; Nyström, M

    2010-01-01

    A review on pulp and paper industrial membrane processes using a variety of modules and processes is presented. Membranes are mostly used today to purify process waters and to recover coating colours. Ultrafiltration using tubular membrane modules or cross-rotational (CR) filtration has been widely applied for the purification of process waters. The reuse of UF membrane permeate has decreased the fresh water consumption to lower than 6 m³/t of paper in some paper machines. Some industrial membrane processes also recover valuable products from different streams (e.g lignosulphonates). Membranes are also combined with biological degradation processes in some paper mills. Nanofiltration has been used to purify the effluents discharged from the activated sludge process. At least two reverse osmosis plants purify river water to be used as raw water in the mill. Furthermore, advantages of different membrane modules and the current ways to treat membrane concentrate are discussed.

  10. The membrane-water interface region of membrane proteins: structural bias and the anti-snorkeling effect.

    PubMed

    Liang, Jie; Adamian, Larisa; Jackups, Ronald

    2005-07-01

    Membrane proteins have important roles in many cellular processes. Computational analysis of their sequences and structures has provided much insight into the organizing principles of transmembrane helices. In a recent study, the membrane-water interface region was examined in detail for the first time. The results have revealed that this interface region has an important role in constraining protein secondary structure. This study raises new questions and opens up new directions for studying membrane proteins.

  11. Water free proton conducting membranes based on poly-4-vinylpyridinebisulfate for fuel cells

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram R. (Inventor); Yen, Shiao-Pin S. (Inventor)

    2007-01-01

    Disclosed are methods for forming a water-free electrolyte membrane useful in fuel cells. Also provided is a water-free electrolyte membrane comprising a quaternized amine salt including poly-4-vinylpyridinebisulfate, a poly-4-vinylpyridinebisulfate silica composite, and a combination thereof and a fuel cell comprising the membrane.

  12. Characterization of organic matter and disinfection by-products in membrane backwash water from drinking water treatment.

    PubMed

    Zhang, Lingling; Gu, Ping; Zhong, Zijie; Yang, Dong; He, Wenjie; Han, Hongda

    2009-09-15

    Two pilot-scale membrane plants were set up to produce drinking water, and membrane backwash water was discharged during the production process. This work studied the characteristics of dissolved organic matter (DOM) in membrane backwash water from submerged microfiltration (MBWS) and pressurized ultrafiltration (MBWP) both of which are coupled with the pre-coagulation process. The results showed that the two waters had similar molecular weight (MW) distributions. Dissolved organic carbon (DOC) and trihalomethane formation potential (THMFP) in MBWS and MBWP were both mainly distributed in MW>30 kDa and MW<1 kDa, and UV(254) was mainly in MW<1 kDa. For Luan River water (LRW, the raw water for the two pilot-scale membrane plants in this study), organic matter enriched in membrane backwash water was mainly in sizes of MW>30 kDa. In addition, organic matter with MW>10 kDa was higher in MBWP than in MBWS. The quality of membrane backwash water was influenced by the changes in LRW quality during different periods. The quality of membrane backwash water was worse in alga-laden period than in normal period and organic matter concentrations in MW<1 kDa increased significantly in this period. The small size DOM in membrane backwash water was more reactive to form trihalomethanes (THMs) in the disinfection process. The variability of specific UV absorbance and THMFP/DOC was consistent in membrane backwash water.

  13. REMOVAL OF MICROBIAL CONTAMINANTS IN DRINKING WATER: KOCH MEMBRANE SYSTEMS, HF-82-35-PMPW™ ULTRAFILTRATION MEMBRANE

    EPA Science Inventory

    Two Koch Membrane Systems HF-82-35-PMPW ultrafiltration membrane cartridges were tested for removal of viruses, bacteria, and protozoan cysts at NSF’s Drinking Water Treatment Systems Laboratory. The ETV testing was conducted as part of a series of evaluations of the Expeditiona...

  14. Mechanics of water pore formation in lipid membrane under electric field

    NASA Astrophysics Data System (ADS)

    Bu, Bing; Li, Dechang; Diao, Jiajie; Ji, Baohua

    2017-02-01

    Transmembrane water pores are crucial for substance transport through cell membranes via membrane fusion, such as in neural communication. However, the molecular mechanism of water pore formation is not clear. In this study, we apply all-atom molecular dynamics and bias-exchange metadynamics simulations to study the process of water pore formation under an electric field. We show that water molecules can enter a membrane under an electric field and form a water pore of a few nanometers in diameter. These water molecules disturb the interactions between lipid head groups and the ordered arrangement of lipids. Following the movement of water molecules, the lipid head groups are rotated and driven into the hydrophobic region of the membrane. The reorientated lipid head groups inside the membrane form a hydrophilic surface of the water pore. This study reveals the atomic details of how an electric field influences the movement of water molecules and lipid head groups, resulting in water pore formation.

  15. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... below the outermost edge of the bridge span structure so as to be visible from an approaching vessel... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span...

  16. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... below the outermost edge of the bridge span structure so as to be visible from an approaching vessel... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span...

  17. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... below the outermost edge of the bridge span structure so as to be visible from an approaching vessel... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span...

  18. High lift selected concepts

    NASA Technical Reports Server (NTRS)

    Henderson, M. L.

    1979-01-01

    The benefits to high lift system maximum life and, alternatively, to high lift system complexity, of applying analytic design and analysis techniques to the design of high lift sections for flight conditions were determined and two high lift sections were designed to flight conditions. The influence of the high lift section on the sizing and economics of a specific energy efficient transport (EET) was clarified using a computerized sizing technique and an existing advanced airplane design data base. The impact of the best design resulting from the design applications studies on EET sizing and economics were evaluated. Flap technology trade studies, climb and descent studies, and augmented stability studies are included along with a description of the baseline high lift system geometry, a calculation of lift and pitching moment when separation is present, and an inverse boundary layer technique for pressure distribution synthesis and optimization.

  19. Water-Free Proton-Conducting Membranes for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram; Yen, Shiao-Pin

    2007-01-01

    Poly-4-vinylpyridinebisulfate (P4VPBS) is a polymeric salt that has shown promise as a water-free proton-conducting material (solid electrolyte) suitable for use in membrane/electrode assemblies in fuel cells. Heretofore, proton-conducting membranes in fuel cells have been made from perfluorinated ionomers that cannot conduct protons in the absence of water and, consequently, cannot function at temperatures >100 C. In addition, the stability of perfluorinated ionomers at temperatures >100 C is questionable. However, the performances of fuel cells of the power systems of which they are parts could be improved if operating temperatures could be raised above 140 C. What is needed to make this possible is a solid-electrolyte material, such as P4VPBS, that can be cast into membranes and that both retains proton conductivity and remains stable in the desired higher operating temperature range. A family of solid-electrolyte materials different from P4VPBS was described in Anhydrous Proton-Conducting Membranes for Fuel Cells (NPO-30493), NASA Tech Briefs, Vol. 29, No. 8 (August 2005), page 48. Those materials notably include polymeric quaternized amine salts. If molecules of such a polymeric salt could be endowed with flexible chain structures, it would be possible to overcome the deficiencies of simple organic amine salts that must melt before being able to conduct protons. However, no polymeric quaternized amine salts have yet shown to be useful in this respect. The present solid electrolyte is made by quaternizing the linear polymer poly- 4-vinylpyridine (P4VP) to obtain P4VPBS. It is important to start with P4VP having a molecular weight of 160,000 daltons because P4VPBS made from lower-molecular-weight P4VP yields brittle membranes. In an experimental synthesis, P4VP was dissolved in methanol and then reacted with an excess of sulfuric acid to precipitate P4VPBS. The precipitate was recovered, washed several times with methanol to remove traces of acid, and dried to a

  20. 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.

  1. Fabrication and Water Treatment Application of Carbon Nanotubes (CNTs)-Based Composite Membranes: A Review

    PubMed Central

    Ma, Lining; Dong, Xinfa; Chen, Mingliang; Zhu, Li; Wang, Chaoxian; Yang, Fenglin; Dong, Yingchao

    2017-01-01

    Membrane separation technology is widely explored for various applications, such as water desalination and wastewater treatment, which can alleviate the global issue of fresh water scarcity. Specifically, carbon nanotubes (CNTs)-based composite membranes are increasingly of interest due to the combined merits of CNTs and membrane separation, offering enhanced membrane properties. This article first briefly discusses fabrication and growth mechanisms, characterization and functionalization techniques of CNTs, and then reviews the fabrication methods for CNTs-based composite membranes in detail. The applications of CNTs-based composite membranes in water treatment are comprehensively reviewed, including seawater or brine desalination, oil-water separation, removal of heavy metal ions and emerging pollutants as well as membrane separation coupled with assistant techniques. Furthermore, the future direction and perspective for CNTs-based composite membranes are also briefly outlined. PMID:28335452

  2. Tunable C2N Membrane for High Efficient Water Desalination

    PubMed Central

    Yang, Yanmei; Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2016-01-01

    Water scarcity represents one of the most serious global problems of our time and challenges the advancements in desalination techniques. Although water-filtering architectures based on graphene have greatly advanced the approach to high performance desalination membranes, the controlled-generation of nanopores with particular diameter is tricky and has stunted its wide applications. Here, through molecular dynamic simulations and first-principles calculations, we propose that the recently reported graphene-like carbon nitride (g-C2N) monolayer can serve as high efficient filters for water desalination. Taking the advantages of the intrisic nanoporous structure and excellent mechanical properties of g-C2N, high water transparency and strong salt filtering capability have been demonstrated in our simulations. More importantly, the “open” and “closed” states of the g-C2N filter can be precisely regulated by tensile strain. It is found that the water permeability of g-C2N is significantly higher than that reported for graphene filters by almost one order of magnitude. In the light of the abundant family of graphene-like carbon nitride monolayered materials, our results thus offer a promising approach to the design of high efficient filteration architectures. PMID:27384666

  3. Tunable C2N Membrane for High Efficient Water Desalination.

    PubMed

    Yang, Yanmei; Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2016-07-07

    Water scarcity represents one of the most serious global problems of our time and challenges the advancements in desalination techniques. Although water-filtering architectures based on graphene have greatly advanced the approach to high performance desalination membranes, the controlled-generation of nanopores with particular diameter is tricky and has stunted its wide applications. Here, through molecular dynamic simulations and first-principles calculations, we propose that the recently reported graphene-like carbon nitride (g-C2N) monolayer can serve as high efficient filters for water desalination. Taking the advantages of the intrisic nanoporous structure and excellent mechanical properties of g-C2N, high water transparency and strong salt filtering capability have been demonstrated in our simulations. More importantly, the "open" and "closed" states of the g-C2N filter can be precisely regulated by tensile strain. It is found that the water permeability of g-C2N is significantly higher than that reported for graphene filters by almost one order of magnitude. In the light of the abundant family of graphene-like carbon nitride monolayered materials, our results thus offer a promising approach to the design of high efficient filteration architectures.

  4. Operation of passive membrane systems for drinking water treatment.

    PubMed

    Oka, P A; Khadem, N; Bérubé, P R

    2017-05-15

    The widespread adoption of submerged hollow fibre ultrafiltration (UF) for drinking water treatment is currently hindered by the complexity and cost of these membrane systems, especially in small/remote communities. Most of the complexity is associated with auxiliary fouling control measures, which include backwashing, air sparging and chemical cleaning. Recent studies have demonstrated that sustained operation without fouling control measures is possible, but little is known regarding the conditions under which extended operation can be sustained with minimal to no fouling control measures. The present study investigated the contribution of different auxiliary fouling control measures to the permeability that can be sustained, with the intent of minimizing the mechanical and operational complexity of submerged hollow fiber UF membrane systems while maximizing their throughput capacity. Sustained conditions could be achieved without backwashing, air sparging or chemical cleaning (i.e. passive operation), indicating that these fouling control measures can be eliminated, substantially simplifying the mechanical and operational complexity of submerged hollow fiber UF systems. The adoption of hydrostatic pressure (i.e. gravity) to provide the driving force for permeation further reduced the system complexity. Approximately 50% of the organic material in the raw water was removed during treatment. The sustained passive operation and effective removal of organic material was likely due to the microbial community that established itself on the membrane surface. The permeability that could be sustained was however only approximately 20% of that which can be maintained with fouling control measures. Retaining a small amount of air sparging (i.e. a few minutes daily) and incorporating a daily 1-h relaxation (i.e. permeate flux interruption) period prior to sparging more than doubled the permeability that could be sustained. Neither the approach used to interrupt the permeate

  5. Water repellent Ag/Ag2O@bamboo cellulose fiber membrane as bioinspired cargo carriers.

    PubMed

    Wang, Yaru; Zhang, Ximu; Zhang, Xiaofang; Zhao, Jiangqi; Zhang, Wei; Lu, Canhui

    2015-11-20

    Water striders can walk on water. To mimic this function, a porous membrane consisted of bamboo cellulose fiber was hybridized with Ag/Ag2O nanoparticles through a facile in situ method to produce water repellent and well-ventilated materials. Herein, we report the sole surface roughness created by Ag/Ag2O nanoparticles could render the membrane a water contact angle (CA) of 140±3.0°. When floating on water, the hybrid membrane was able to support a heavy load more than 10 times the weight of the membrane itself. Additionally, this membrane demonstrated capabilities for oil sampling under water or oil/water separation and strong antibacterial activity against Escherichia coli. Thus we foresee that this novel hybrid membrane can be potentially utilized as drag-reducing, gas permeable and antibiotic substrates for constructing miniature aquatic devices.

  6. Hepatocyte membrane water permeability measured by silicone layer filtering centrifugation.

    PubMed

    Gradilone, Sergio A; Ochoa, J Elena; García, Fabiana; Larocca, M Cecilia; Pellegrino, José M; Marinelli, Raúl A

    2002-03-01

    We previously found that hepatocytes are able to control their osmotic membrane water permeability (P(f)) by regulating the number of surface aquaporin water channels. Hepatocyte P(f) has been assessed by phase-contrast microscopy and cell image analysis, an established but relatively laborious procedure. We report here an alternative method to assess hepatocyte P(f) based on a single silicone layer filtering centrifugation system. Isolated rat hepatocytes were incubated in hypotonic or isotonic buffers containing (3)H(2)O as a tracer and, then, were filtered by rapid centrifugation through a silicone layer down to a lysis layer. Osmotically driven radioactivity (i.e., (3)H(2)O) within hepatocytes was calculated as the difference between the dpm in lysis media measured under hypotonic and isotonic conditions. The P(f) calculated from the initial slope of the radioactivity-versus-time curve was 18 microm/s at 4 degrees C. Hepatocytes treated with dibutyryl cyclic AMP, to increase P(f) through the plasma membrane insertion of aquaporins, showed an increased P(f) value of 37 microm/s. The aquaporin blocker dimethyl sulfoxide selectively prevented the agonist-induced hepatocyte P(f). These data are in good agreement with the corresponding values determined by quantitative phase-contrast microscopy; thus, the method developed allows the rapid and reliable measurement of hepatocyte P(f).

  7. Development of an integrated membrane process for water reclamation.

    PubMed

    Lew, C H; Hu, J Y; Song, L F; Lee, L Y; Ong, S L; Ng, W J; Seah, H

    2005-01-01

    An integrated membrane process (IMP) comprising a membrane bioreactor (MBR) and a reverse osmosis (RO) process was developed for water reclamation. Wastewater was treated by an MBR operated at a sludge retention time (SRT) of 20 days and a hydraulic retention time (HRT) of 5.5 h. The IMP had an overall recovery efficiency of 80%. A unique feature of the IMP was the recycling of a fraction of RO concentrate back to the MBR. Experimental results revealed that a portion of the slow- and hard-to-degrade organic constituents in the recycle stream could be degraded by an acclimated biomass leading to an improved MBR treatment efficiency. Although recycling concentrated constituents could impose an inhibitory effect on the biomass and suppress their respiratory activities, results obtained suggested that operating MBR (in the novel IMP) at an F/M ratio below 0.03 g TOC/g VSS.day could yield an effluent quality comparable to that achievable without concentrate recycling. It is noted in this study that the novel IMP could achieve an average overall TOC removal efficiency of 88.940% and it consistently produced product water usable for high value reuse applications.

  8. Pervaporation properties of dense polyamide-6 membranes in separation of water-ethanol mixtures

    SciTech Connect

    Kujawski, W.; Waczynski, M.; Lasota, M.

    1996-04-01

    Several dense polyamide-6 membranes were prepared by casting 7 wt% and/or 10 wt% solutions of polymer in trifluoroethanol. The cast membranes were dried at different temperatures from 25 to 80{degrees}C. Sorption and pervaporation properties of PA-6 membranes in water-ethanol mixtures were obtained. The data obtained showed that water was preferentially sorbed into the membrane and transported through the membrane; however, the pervaporation selectivity factor {alpha}{sup PV} was close to unity at higher concentrations. The selectivity parameters in pervaporation were improved for membranes obtained from 10 wt% polymer and dried at higher temperatures.

  9. A facile TiO2/PVDF composite membrane synthesis and their application in water purification

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Zhang, Yiming; Fan, Rong; Lewis, Rosmala

    2016-01-01

    In this work, we have demonstrated a facile wet chemical method to synthesise TiO2/PVDF composite membranes as alternative water purification method to traditional polymer-based membrane. For the first time, hydrothermally grown TiO2 nanofibers under alkali conditions were successfully inserted into PVDF membranes matrix. The structure, permeability and anti-fouling performance of as-prepared PVDF/TiO2 composite membranes were studied systematically. The TiO2/PVDF composite membranes prepared in this work promise great potential uses in water purification applications as microfiltration membranes due to its excellent physical/chemical resistance, anti-fouling and mechanical properties.

  10. Distribution of Fullerene Nanoparticles between Water and Solid Supported Lipid Membranes: Thermodynamics and Effects of Membrane Composition on Distribution.

    PubMed

    Ha, Yeonjeong; Katz, Lynn E; Liljestrand, Howard M

    2015-12-15

    The distribution coefficient (Klipw) of fullerene between solid supported lipid membranes (SSLMs) and water was examined using different lipid membrane compositions. Klipw of fullerene was significantly higher with a cationic lipid membrane compared to that with a zwitterionic or anionic lipid membrane, potentially due to the strong interactions between negative fullerene dispersions and positive lipid head groups. The higher Klipw for fullerene distribution to ternary lipid mixture membranes was attributed to an increase in the interfacial surface area of the lipid membrane resulting from phase separation. These results imply that lipid composition can be a critical factor that affects bioconcentration of fullerene. Distribution of fullerene into zwitterionic unsaturated lipid membranes was dominated by the entropy contribution (ΔS) and the process was endothermic (ΔH > 0). This result contrasts the partitioning thermodynamics of highly and moderately hydrophobic chemicals indicating that the lipid-water distribution mechanism of fullerene may be different from that of molecular level chemicals. Potential mechanisms for the distribution of fullerene that may explain these differences include adsorption on the lipid membrane surfaces and partitioning into the center of lipid membranes (i.e., absorption).

  11. Effects of pressure reductions in a proposed siphon water lift system at St. Stephen Dam, South Carolina, on mortality rates of juvenile American shad and blueback herring. Technical report

    SciTech Connect

    Nestler, J.M.; Schilt, C.R.; Jones, D.P.

    1998-09-01

    This report presents results of studies to predict the mortality rate of juvenile blueback herring (Alosa aestivalis) and American shad (A. sapidissima) associated with reduced pressure as they pass downstream through a proposed siphon water lift system at St. Stephen Dam, South Carolina. The primary function of the siphon is to increase attracting flow to better guide upstream migrating adult herring of both species into the existing fish lift for upstream passage. The US Army Engineer District, Charleston, wishes to consider the siphon as an alternative bypass route through the dam for downstream migrating juvenile and adult herring. A pressure-reduction testing system that emulates some of the pressure characteristics of the siphon was used to determine the approximate percentage of juvenile fishes that could be reasonably expected to be killed passing through the reduced pressures anticipated for the siphon water lift system. The testing system could duplicate the range of pressure change anticipated for the siphon lift system but could not obtain pressures lower than 4.1 psi, whereas pressures for some design alternatives may approach the theoretical minimum pressure of 0.0 psi. Study results indicate that the mortality rate is probably about 20 percent. Power analysis indicates that mortality rate above 30 percent is unlikely. Conducting additional mortality studies is recommended to refine predicted mortality rates. Measures should be taken to prevent juvenile fish from entering the siphon lift system if excessive mortality rates are observed.

  12. Water reclamation during drinking water treatments using polyamide nanofiltration membranes on a pilot scale.

    PubMed

    Kukučka, Miroslav; Kukučka, Nikoleta; Habuda-Stanić, Mirna

    2016-09-01

    The aim of this study was to investigate the performances of polyamide nanofiltration membranes during water reclamation. The study was conducted using nanofiltration concentrates obtained from two different nanofiltration drinking water treatment plants placed in the northern part of Serbia (Kikinda and Zrenjanin). Used nanofiltration concentrates contained high concentrations of arsenic (45 and 451 μg/L) and natural organic matter (43.1 and 224.40 mgKMnO4/L). Performances of polyamide nanofiltration membranes during water reclamation were investigated under various fluxes and transmembrane pressures in order to obtain drinking water from nanofiltration concentrates and, therefore, reduce the amount of produced concentrates and minimize the waste that has to be discharged in the environment. Applied polyamide nanofiltration membranes showed better removal efficiency during water reclamation when the concentrate with higher content of arsenic and natural organic matter was used while the obtained permeates were in accordance with European regulations. This study showed that total concentrate yield can be reduced to ~5 % of the optimum flux value, in both experiments. The obtained result for concentrate yield under the optimum flux presents considerable amount of reclaimed drinking water and valuable reduced quantity of produced wastewater.

  13. Polymeric Membrane Made of Cellulose Isolated from Tropical Water Hyacinth Blended with Chitosan

    NASA Astrophysics Data System (ADS)

    Istirokhatun, Titik; Rachmawaty, Richa; Meriyani, Metty; Rokhati, Nur; Susanto, Heru

    2017-02-01

    In Indonesia, membrane application is limited by the use of high cost imported membranes. Therefore, efforts to produce membrane using local materials are very important to be performed. Cellulose and chitosan are two materials, which their availability in Indonesia is abundant. In this work, cellulose acetate (CA) has been successfully produced from tropical water hyacinth via isolation and acetylation processes. By using FTIR, a comparative analysis of functional groups between the resulted CA and commercial CA was also investigated. The result shows that the IR spectra of the resulted CA and commercial CA are similar. The produced CA can further be processed into membrane. The resulting membranes were then characterized using SEM. In addition, the membranes were examined for filtering humic acid solution as surface water model. To improve the performance, CA membranes prepared from water hyacinth were modified by addition of chitosan (Chi) via blending in phase separation method. The resulting CA-Chi membranes were characterized using SEM and FTIR.

  14. Evidence of hydraulic lift for pre-rainy season leaf out and dry-season stem water enrichment in Sclerocarya birrea, a tropical agroforestry tree

    NASA Astrophysics Data System (ADS)

    Ceperley, Natalie; Mande, Theophile; Rinaldo, Andrea; Parlange, Marc B.

    2014-05-01

    We use stable isotopes of water as tracers to follow water use by five Sclerocarya birrea trees in a catchment in South Eastern Burkina Faso interspersed with millet fields, gallery forest, Sudanian savanna, and fallow fields. Isotopic ratios were determined from water extracted from stems of the trees and sub-canopy soil of two of them, while nearby ground water, precipitation, and surface water was sampled weekly. A unique configuration of sensors connected with a wireless sensor network of meteorological stations measured sub-canopy shading, the temperature and humidity in the canopy, through-fall, and soil moisture under two of the trees. Both water extracted from sap and water extracted from soil is extremely enriched in the dry season, but drop to levels close to the ground water in February or March, which coincides with the growth of leaves. Dates of leaf out were confirmed by changes in δDH and δO18 concentrations of water, photographic documentation & pixel analysis, and analysis of sub-canopy radiation and proceeded the rise in humidity and flow that was later detected in the sub-canopy soil, the trunk of the tree (sap-flow), and atmosphere (canopy VPD). Examination of the isotopic signature suggests that size of tree plays an important role in duration and timing of this leaf-out as well as the degree of enrichment during the peak of the dry season. Further examination of the isotopic signatures of the roots suggested that the trees are performing hydraulic redistribution, or lifting the ground water and "sharing it" with the soil in the rooting zone in the dry season. The enriched level of xylem in this case is a product of water loss, and enrichment, along the travel path of the water from the roots to the tip of the stem, as evidenced by the variation according to size of tree. Vapor pressure deficit, soil water, and soil moisture interactions support this picture of interacting controls, separate from hydrologic triggers on the water movement in

  15. Self-Sealing and Puncture Resistant Breathable Membranes for Water-Evaporation Applications.

    PubMed

    Rother, Martin; Barmettler, Jonas; Reichmuth, Andreas; Araujo, Jose V; Rytka, Christian; Glaied, Olfa; Pieles, Uwe; Bruns, Nico

    2015-11-01

    Breathable and waterproof membranes that self-seal damaged areas are prepared by modifying a poly(ether ester) membrane with an amphiphilic polymer co-network. The latter swells in water and the gel closes punctures. Damaged composite membranes remain water tight up to pressures of at least 1.6 bar. This material is useful for applications where water-vapor permeability, self-sealing properties, and waterproofness are desired, as demonstrated for a medical cooling device.

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

    SciTech Connect

    Duan, QJ; Ge, SH; Wang, CY

    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. (C) 2013 Elsevier B.V. All rights reserved.

  17. Water vapor sorption thermodynamics of the Nafion ionomer membrane.

    PubMed

    Wadsö, Lars; Jannasch, Patric

    2013-07-18

    The water interactions of polymer electrolyte membranes are of significant interest when these materials are used in, for example, fuel cells. We have therefore studied the sorption thermodynamics of Nafion with a sorption calorimeter that simultaneously measures the sorption isotherm and the mixing (sorption) enthalpy. This unique method is suitable for investigating the sorption thermodynamics of ionic polymers. The measurements were made at 25 °C on a series of samples dried at different temperatures from 25 to 120 °C. The sorption isotherms indicate that the samples dried at 120 °C lost about 0.8 more water molecules per sulfonic group during the drying than did the samples dried at 25 °C, and this result was verified gravimetrically. The mixing enthalpies showed several peaks or plateaus for the samples dried at 60-120 °C. This behavior was seen up to about 2 water molecules per sulfonic group. As these peaks were not directly related to any feature in the sorption isotherm, they probably have their origin in a secondary process, such as a reorganization of the polymer.

  18. Ionic site imaging in polymer membranes for water filtration applications

    NASA Astrophysics Data System (ADS)

    Rothe, Deborah Ruth

    The morphologies of ionic domains within poly(styrene-co-acrylic acid) (SAA) copolymers and sulfonated biphenyl sulfone (BPS) copolymers neutralized with Cu(II) were investigated using scanning transmission electron microscopy (STEM) and X-ray scattering. The ionic domain size for the SAA copolymers was independent of acid content while the BPS copolymers revealed an increase in ionic aggregate diameter with increasing sulfonate content. STEM imaging revealed large ionic groups in the higher sulfonate-containing polymer. It was the higher sulfonate material which had high water flux but poorer salt rejection properties. Additional analysis of the BPS copolymers with differential scanning calorimetry (DSC) did not show a detectable glass transition temperature (Tg), suggesting a distribution of ionic interactions which tethered polymer chains, restricting their mobility and governed thermal behavior. These results suggest the heterogeneous distribution of large ionic domains within the BPS polymer that may facilitate salt transport through the membrane via overlapping ion rich regions.

  19. Selective Removal of Technetium from Water Using Graphene Oxide Membranes.

    PubMed

    Williams, Christopher D; Carbone, Paola

    2016-04-05

    The effective removal of radioactive technetium ((99)Tc) from contaminated water is of enormous importance from an environmental and public health perspective, yet many current methodologies are highly ineffective. In this work, however, we demonstrate that graphene oxide membranes may remove (99)Tc, present in the form of pertechnetate (TcO4(-)), from water with a high degree of selectivity, suggesting they provide a cost-effective and efficient means of achieving (99)Tc decontamination. The results were obtained by quantifying and comparing the free energy changes associated with the entry of the ions into the membrane capillaries (ΔFperm), using molecular dynamics simulations. Initially, three capillary widths were investigated (0.35, 0.68, and 1.02 nm). In each case, the entry of TcO4(-) from aqueous solution into the capillary is associated with a decrease in free energy, unlike the other anions (SO4(2-), I(-), and Cl(-)) investigated. For example, in the model with a capillary width of 0.68 nm, ΔFperm(TcO4(-)) = -6.3 kJ mol(-1), compared to ΔFperm(SO4(2-)) = +22.4 kJ mol(-1). We suggest an optimum capillary width (0.48 nm) and show that a capillary with this width results in a difference between ΔFperm(TcO4(-)) and ΔFperm(SO4(2-)) of 89 kJ mol(-1). The observed preference for TcO4(-) is due to its weakly hydrating nature, reflected in its low experimental hydration free energy.

  20. Structural transition of actin filament in a cell-sized water droplet with a phospholipid membrane

    NASA Astrophysics Data System (ADS)

    Hase, M.; Yoshikawa, K.

    2006-03-01

    Actin filament, F-actin, is a semiflexible polymer with a negative charge, and is one of the main constituents of cell membranes. To clarify the effect of cross talk between a phospholipid membrane and actin filaments in cells, we conducted microscopic observations on the structural changes in actin filaments in a cell-sized (several tens of micrometers in diameter) water droplet coated with a phospholipid membrane such as phosphatidylserine (PS; negatively charged head group) or phosphatidylethanolamine (PE; neutral head group) as a simple model of a living cell membrane. With PS, actin filaments are distributed uniformly in the water phase without adsorption onto the membrane surface between 2 and 6mM Mg2+, while between 6 and 12mM Mg2+, actin filaments are adsorbed onto the inner membrane surface. With PE, the actin filaments are uniformly adsorbed onto the inner membrane surface between 2 and 12mM Mg2+. With both PS and PE membranes, at Mg2+ concentrations higher than 12mM, thick bundles are formed in the bulk water droplet accompanied by the dissolution of actin filaments from the membrane surface. The attraction between actin filaments and membrane is attributable to an increase in the translational entropy of counterions accompanied by the adsorption of actin filaments onto the membrane surface. These results suggest that a microscopic water droplet coated with phospholipid can serve as an easy-to-handle model of cell membranes.

  1. Pretreatment of agriculture field water for improving membrane flux during pesticide removal

    NASA Astrophysics Data System (ADS)

    Mehta, Romil; Saha, N. K.; Bhattacharya, A.

    2016-09-01

    Pretreatment of feed water to improve membrane flux during filtration of agriculture field water containing substituted phenyl urea pesticide diuron has been reported. Laboratory-made reverse osmosis membrane was used for filtration. Preliminary experiments were conducted with model solution containing natural organic matter extracted from commercial humic acids, divalent ions Ca2+, Mg2+. Membrane fouling was characterized by pure water flux decline, change in membrane hydrophilicity and infrared spectroscopy. Natural organic matter present in field water causes severe membrane fouling. The presence of divalent cations further aggravated fouling. Use of ethylenediaminetetraacetic acid (EDTA) and polyacrylic acids (PAA) in feed resulted in the decrease in membrane fouling. Pretreatment of field water is a must if it is contaminated with micro-organism having membrane fouling potential. Feed water pretreatment and use of PAA restricted membrane fouling to 16 % after 60 h of filtration. Membrane permeate flux decline was maximum at the first 12 h and thereafter remained steady at around 45-46 lm-2h-1 till the end of 60 h. Diuron rejection remained consistently greater than 93 % throughout the experiment. Diuron rejection was found to be unaffected by membrane fouling.

  2. Separation of alcohol-water mixture by pervaporation through a reinforced polyvinylpyridine membrane

    SciTech Connect

    Uramoto, Hiromu; Kawabata, Nariyoshi . Dept. of Chemistry and Materials Technology)

    1993-10-05

    A membrane consisted of cross-linked poly (4-vinylpyridine) and reinforced by a nonwoven cloth made of poly (ethylene terephthalate) was prepared by copolymerization of 4-vinyl-pyridine with divinylbenzene in the presence of the nonwoven cloth. Pervaporation performance of this polyvinylpyridine membrane was examined at several feed alcohol concentrations and temperatures. The membrane showed water selectivity, and the permselectivity, [alpha][sub W/A], for the alcohol-water mixture was in the order isopropyl > propyl > tertbutyl > ethyl > methyl. The membranes showed a large permeability, and the pervaporation flux, [phi], for the ethanol-water mixtures was 7-13 kg/h per square meter of the membrane in pervaporation with sweeping of carbon dioxide under atmospheric pressure and at 40 C. The membrane was durable and long lasting for a prolonged-period, and permselectivity and permeability of the membrane did not fall off even after repeated use for 1000 h.

  3. Molecular Dynamics Studies of Structure and Functions of Water-Membrane Interfaces

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Wilson, Michael A.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    A large number of essential cellular processes occur at the interfaces between water and membranes. The selectivity and dynamics of these processes are largely determined by the structural and electrical properties of the water-membrane interface. We investigate these properties by the molecular dynamics method. Over the time scales of the simulations, the membrane undergoes fluctuations described by the capillary wave model. These fluctuations produce occasional thinning defects in the membrane which provide effective pathways for passive transport of ions and small molecules across the membrane. Ions moving through the membrane markedly disrupt its structure and allow for significant water penetration into the membrane interior. Selectivity of transport, with respect to ionic charge, is determined by the interfacial electrostatic potential. Many small molecules. of potential significance in catalysis, bioenergetics and pharmacology, are shown to bind to the interface. The energetics and dynamics of this process will be discussed.

  4. Modeling the improvement of ultrafiltration membrane mass transfer when using biofiltration pretreatment in surface water applications.

    PubMed

    Netcher, Andrea C; Duranceau, Steven J

    2016-03-01

    In surface water treatment, ultrafiltration (UF) membranes are widely used because of their ability to supply safe drinking water. Although UF membranes produce high-quality water, their efficiency is limited by fouling. Improving UF filtrate productivity is economically desirable and has been attempted by incorporating sustainable biofiltration processes as pretreatment to UF with varying success. The availability of models that can be applied to describe the effectiveness of biofiltration on membrane mass transfer are lacking. In this work, UF water productivity was empirically modeled as a function of biofilter feed water quality using either a quadratic or Gaussian relationship. UF membrane mass transfer variability was found to be governed by the dimensionless mass ratio between the alkalinity (ALK) and dissolved organic carbon (DOC). UF membrane productivity was optimized when the biofilter feed water ALK to DOC ratio fell between 10 and 14.

  5. Hollow Fiber Spacesuit Water Membrane Evaporator Development and Testing for Advanced Spacesuits

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Trevino, Luis; Tsioulos, Gus; Settles, Joseph; Colunga, Aaron; Vogel, Matthew; Vonau, Walt

    2010-01-01

    Grant Bue and Matthew Vogel presented the two types of Spacesuit Water Membrane Evaporators (SWME) that were developed based on hydrophobic microporous membranes. One type, the Sheet Membrane (SaM) SWME, is composed of six concentric Teflon sheet membranes fixed on cylindrical-supporting screens to form three concentric annular water channels. Those water channels are surrounded by vacuum passages to draw off the water vapor that passes through the membrane. The other type, the Hollow Fiber (HoFi) SWME, is composed of more than 14,000 tubes. Water flows through the tubes and water vapor passes through the tube wall to the shell side that vents to the vacuum of space. Both SWME types have undergone testing to baseline the performance at predicted operating temperatures and flow rates; the units also have been subjected to contamination testing and other conditions to test resiliency.

  6. Transport of water and solutes in reverse osmosis and nanofiltration membranes

    NASA Astrophysics Data System (ADS)

    Cahill, David

    2009-03-01

    The polyamide active layers of reverse osmosis and nanofiltration membranes used for water purification are real-world examples of nanoscale functional materials: the active layer is only ˜100 nm thick. Because the active layer is formed by a process of interfacial polymerization, the structure and composition of the membrane is highly inhomogeneous and even such basic physical and chemical properties as the atomic density, swelling in water, the distribution of charged species between water and membrane, and the mobility of water and ions, are poorly understood. We are using Rutherford backscattering spectrometry (RBS) to determine the composition, roughness, and thickness of the membrane; reveal the surprisingly high solubility of salt ions in the polymer active layer; analyze the acid-base chemistry of charged functional groups; and determine the degree of polymer cross-linking. Measurements of mass-uptake and adsorption-induced mechanical stress of membranes in humid air enable us to determine the water solubility, specific volume of water, and the mechanical strength of the membrane. Comparisons between these equilibrium data and the permeability of the membrane to water and salts show that the mobility of water molecules in the membrane approaches the mobility of bulk water, and that the rejection of salt ions is accomplished by low mobility, not low solubility. My collaborators in this work are Xijing Zhang, Orlando Coronell, and Prof. Benito Mariñas.

  7. Catwalk grate lifting tool

    DOEpatents

    Gunter, L.W.

    1992-08-11

    A device is described for lifting catwalk grates comprising an elongated bent member with a handle at one end and a pair of notched braces and a hook at the opposite end that act in conjunction with each other to lock onto the grate and give mechanical advantage in lifting the grate. 10 figs.

  8. Catwalk grate lifting tool

    DOEpatents

    Gunter, Larry W.

    1992-01-01

    A device for lifting catwalk grates comprising an elongated bent member with a handle at one end and a pair of notched braces and a hook at the opposite end that act in conjunction with each other to lock onto the grate and give mechanical advantage in lifting the grate.

  9. High lift aerodynamics

    NASA Technical Reports Server (NTRS)

    Sullivan, John; Schneider, Steve; Campbell, Bryan; Bucci, Greg; Boone, Rod; Torgerson, Shad; Erausquin, Rick; Knauer, Chad

    1994-01-01

    The current program is aimed at providing a physical picture of the flow physics and quantitative turbulence data of the interaction of a high Reynolds number wake with a flap element. The impact of high lift on aircraft performance is studied for a 150 passenger transport aircraft with the goal of designing optimum high lift systems with minimum complexity.

  10. Portable Lifting Seat

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce

    1993-01-01

    Portable lifting machine assists user in rising from seated position to standing position, or in sitting down. Small and light enough to be carried like briefcase. Used on variety of chairs and benches. Upholstered aluminum box houses mechanism of lifting seat. Springs on outer shaft-and-arm subassembly counterbalance part of user's weight to assist motor.

  11. Understanding Wing Lift

    ERIC Educational Resources Information Center

    Silva, J.; Soares, A. A.

    2010-01-01

    The conventional explanation of aerodynamic lift based on Bernoulli's equation is one of the most common mistakes in presentations to school students and is found in children's science books. The fallacies in this explanation together with an alternative explanation for aerofoil lift have already been presented in an excellent article by Babinsky…

  12. Portable seat lift

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce (Inventor)

    1994-01-01

    A portable seat lift that can help individuals either (1) lower themselves to a sitting position or (2) raise themselves to a standing position is presented. The portable seat lift consists of a seat mounted on a base with two levers, which are powered by a drive unit.

  13. Cross-linked high conductive membranes based on water soluble ionomer for high performance proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Jiang, Hao; Guo, Xin; Zhang, Gang; Ni, Jing; Zhao, Chengji; Liu, Zhongguo; Zhang, Liyuan; Li, Mingyu; Xu, Shuai; Na, Hui

    2013-11-01

    In this paper, a series of proton exchange membranes prepared by “Click Reaction” are reported. The cross-linked membranes are based on water soluble sulfonated poly (ether ether ketone) containing dipropenyl groups (SDPEEK-nE/nH). Compared with self-crosslinked membranes (SDPEEK-nS), this “Click” cross-linked membranes using 1,2-Ethanedithiol and 1,6-Hexanedithiol as the cross-linker exhibit extremely reduced water uptake and swelling ratio. The lowest proton conductivity at 80 °C of the “Click” cross-linked membranes reaches to 0.168 S cm-1, and the highest methanol permeability of the “Click” cross-linked SDPEEK-8E is only 4.13 × 10-7 cm2 s-1, which is 5 times lower than that of Nafion 117 membrane. All the results imply that the cross-linked membranes with novel thiol cross-linker are promising alternative material for fuel cell application.

  14. Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Rector, Tony; Peyton, Barbara M.; Steele, John W.; Makinen, Janice; Bue, Grant C.; Campbell, Colin

    2014-01-01

    Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a recirculating control loop which had no water quality maintenance. Results show that periodic water maintenance can improve performance of the SWME. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage of this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the evaluation of water recirculation maintenance components was to enhance the robustness of the SWME through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A patented bed design that was developed for a United Technologies Aerospace System military application provided a low pressure drop means for water maintenance in the SWME recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for the ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

  15. Removal of bisphenol A (BPA) from water by various nanofiltration (NF) and reverse osmosis (RO) membranes.

    PubMed

    Yüksel, Suna; Kabay, Nalan; Yüksel, Mithat

    2013-12-15

    The removal of an endocrine disrupting compound, bisphenol A (BPA), from model solutions by selected nanofiltration (NF) and reverse osmosis (RO) membranes was studied. The commercially available membranes NF 90, NF 270, XLE BWRO, BW 30 (Dow FilmTech), CE BWRO and AD SWRO (GE Osmonics) were used to compare their performances for BPA removal. The water permeability coefficients, rejection of BPA and permeate flux values were calculated for all membranes used. No significant changes in their BPA removal were observed for all tight polyamide based NF and RO membranes tested except for loose NF 270 membrane. The polyamide based membranes exhibited much better performance than cellulose acetate membrane for BPA removal. Almost a complete rejection (≥ 98%) for BPA was obtained with three polyamide based RO membranes (BW 30, XLE BWRO and AD SWRO). But cellulose acetate based CE BWRO membrane offered a low and variable (10-40%) rejection for BPA.

  16. Antimicrobial PVK:SWNT nanocomposite coated membrane for water purification: performance and toxicity testing.

    PubMed

    Ahmed, Farid; Santos, Catherine M; Mangadlao, Joey; Advincula, Rigoberto; Rodrigues, Debora F

    2013-08-01

    This study demonstrated that coated nitrocellulose membranes with a nanocomposite containing 97% (wt%) of polyvinyl-N-carbazole (PVK) and 3% (wt%) of single-walled carbon nanotubes (SWNTs) (97:3 wt% ratio PVK:SWNT) achieve similar or improved removal of bacteria when compared with 100% SWNTs coated membranes. Membranes coated with the nanocomposite exhibited significant antimicrobial activity toward Gram-positive and Gram-negative bacteria (≈ 80-90%); and presented a virus removal efficiency of ≈ 2.5 logs. Bacterial cell membrane damage was considered a possible mechanism of cellular inactivation since higher efflux of intracellular material (Deoxyribonucleic acid, DNA) was quantified in the filtrate of PVK-SWNT and SWNT membranes than in the filtrate of control membranes. To evaluate possible application of these membrane filters for drinking water treatment, toxicity of PVK-SWNT was tested against fibroblast cells. The results demonstrated that PVK-SWNT was non toxic to fibroblast cells as opposed to pure SWNT (100%). These results suggest that it is possible to synthesize antimicrobial nitrocellulose membranes coated with SWNT based nanocomposites for drinking water treatment. Furthermore, membrane filters coated with the nanocomposite PVK-SWNT (97:3 wt% ratio PVK:SWNT) will produce more suitable coated membranes for drinking water than pure SWNTs coated membranes (100%), since the reduced load of SWNT in the nanocomposite will reduce the use of costly and toxic SWNT nanomaterial on the membranes.

  17. Surface modification of cellulose acetate membrane using thermal annealing to enhance produced water treatment

    SciTech Connect

    Kusworo, T. D. Aryanti, N. Firdaus, M. M. H.; Sukmawati, H.

    2015-12-29

    This study is performed primarily to investigate the effect of surface modification of cellulose acetate using thermal annealing on the enhancement of membrane performance for produced water treatment. In this study, Cellulose Acetate membranes were casted using dry/wet phase inversion technique. The effect of additive and post-treatment using thermal annealing on the membrane surface were examined for produced water treatment. Therma annealing was subjected to membrane surface at 60 and 70 °C for 5, 10 and 15 second, respectively. Membrane characterizations were done using membrane flux and rejection with produced water as a feed, Scanning Electron Microscopy (SEM) and Fourier Transform Infra Red (FTIR) analysis. Experimental results showed that asymmetric cellulose acetate membrane can be made by dry/wet phase inversion technique. The results from the Scanning Electron Microscopy (FESEM) analysis was also confirmed that polyethylene glycol as additivie in dope solution and thermal annealing was affected the morphology and membrane performance for produced water treatment, respectively. Scanning electron microscopy micrographs showed that the selective layer and the substructure of membrane became denser and more compact after the thermal annealing processes. Therefore, membrane rejection was significantly increased while the flux was slighty decreased, respectively. The best membrane performance is obtained on the composition of 18 wt % cellulose acetate, poly ethylene glycol 5 wt% with thermal annealing at 70° C for 15 second.

  18. Surface modification of cellulose acetate membrane using thermal annealing to enhance produced water treatment

    NASA Astrophysics Data System (ADS)

    Kusworo, T. D.; Aryanti, N.; Firdaus, M. M. H.; Sukmawati, H.

    2015-12-01

    This study is performed primarily to investigate the effect of surface modification of cellulose acetate using thermal annealing on the enhancement of membrane performance for produced water treatment. In this study, Cellulose Acetate membranes were casted using dry/wet phase inversion technique. The effect of additive and post-treatment using thermal annealing on the membrane surface were examined for produced water treatment. Therma annealing was subjected to membrane surface at 60 and 70 °C for 5, 10 and 15 second, respectively. Membrane characterizations were done using membrane flux and rejection with produced water as a feed, Scanning Electron Microscopy (SEM) and Fourier Transform Infra Red (FTIR) analysis. Experimental results showed that asymmetric cellulose acetate membrane can be made by dry/wet phase inversion technique. The results from the Scanning Electron Microscopy (FESEM) analysis was also confirmed that polyethylene glycol as additivie in dope solution and thermal annealing was affected the morphology and membrane performance for produced water treatment, respectively. Scanning electron microscopy micrographs showed that the selective layer and the substructure of membrane became denser and more compact after the thermal annealing processes. Therefore, membrane rejection was significantly increased while the flux was slighty decreased, respectively. The best membrane performance is obtained on the composition of 18 wt % cellulose acetate, poly ethylene glycol 5 wt% with thermal annealing at 70° C for 15 second.

  19. Samus Counter Lifting Fixture

    SciTech Connect

    Stredde, H.; /Fermilab

    1998-05-27

    A lifting fixture has been designed to handle the Samus counters. These counters are being removed from the D-zero area and will be transported off site for further use at another facility. This fixture is designed specifically for this particular application and will be transferred along with the counters. The future use of these counters may entail installation at a facility without access to a crane and therefore a lift fixture suitable for both crane and/or fork lift usage has been created The counters weigh approximately 3000 lbs. and have threaded rods extended through the counter at the top comers for lifting. When these counters were first handled/installed these rods were used in conjunction with appropriate slings and handled by crane. The rods are secured with nuts tightened against the face of the counter. The rod thread is M16 x 2({approx}.625-inch dia.) and extends 2-inch (on average) from the face of the counter. It is this cantilevered rod that the lift fixture engages with 'C' style plates at the four top comers. The strongback portion of the lift fixture is a steel rectangular tube 8-inch (vertical) x 4-inch x .25-inch wall, 130-inch long. 1.5-inch square bars are welded perpendicular to the long axis of the rectangular tube at the appropriate lift points and the 'C' plates are fastened to these bars with 3/4-10 high strength bolts -grade 8. Two short channel sections are positioned-welded-to the bottom of the rectangular tube on 40 feet centers, which are used as locators for fork lift tines. On the top are lifting eyes for sling/crane usage and are rated at 3500 lbs. safe working load each - vertical lift only.

  20. Free-Standing Graphene Oxide-Palygorskite Nanohybrid Membrane for Oil/Water Separation.

    PubMed

    Zhao, Xueting; Su, Yanlei; Liu, Yanan; Li, Yafei; Jiang, Zhongyi

    2016-03-01

    Graphene oxide (GO) is an emerging kind of building block for advanced membranes with tunable passageway for water molecules. To synergistically manipulate the channel and surface structures/properties of GO-based membranes, the different building blocks are combined and the specific interfacial interactions are designed in this study. With vacuum-assisted filtration self-assembly, palygorskite nanorods are intercalated into adjacent GO nanosheets, and GO nanosheets are assembled into laminate structures through π-π stacking and cation cross-linking. The palygorskite nanorods in the free-standing GOP nanohybrid membranes take a 3-fold role, rendering enlarged mass transfer channels, elevating hydration capacity, and creating hierarchical nanostructures of membrane surfaces. Accordingly, the permeate fluxes from 267 L/(m(2) h) for GO membrane to 1867 L/(m(2) h) for GOP membrane. The hydration capacity and hierarchical nanostructures synergistically endow GOP membranes with underwater superoleophobic and low oil-adhesive water/membrane interfaces. Moreover, by rationally imparting chemical and physical joint defense mechanisms, the GOP membranes exhibit outstanding separation performance and antifouling properties for various oil-in-water emulsion systems (with different concentration, pH, or oil species). The high water permeability, high separation efficiency, as well as superior anti-oil-fouling properties of GOP membranes enlighten the great prospects of graphene-based nanostructured materials in water purification and wastewater treatment.

  1. Zeolite Membrane Reactor for Water Gas Shift Reaction for Hydrogen Production

    SciTech Connect

    Lin, Jerry Y.S.

    2013-01-29

    Gasification of biomass or heavy feedstock to produce hydrogen fuel gas using current technology is costly and energy-intensive. The technology includes water gas shift reaction in two or more reactor stages with inter-cooling to maximize conversion for a given catalyst volume. This project is focused on developing a membrane reactor for efficient conversion of water gas shift reaction to produce a hydrogen stream as a fuel and a carbon dioxide stream suitable for sequestration. The project was focused on synthesizing stable, hydrogen perm-selective MFI zeolite membranes for high temperature hydrogen separation; fabricating tubular MFI zeolite membrane reactor and stable water gas shift catalyst for membrane reactor applications, and identifying experimental conditions for water gas shift reaction in the zeolite membrane reactor that will produce a high purity hydrogen stream. The project has improved understanding of zeolite membrane synthesis, high temperature gas diffusion and separation mechanisms for zeolite membranes, synthesis and properties of sulfur resistant catalysts, fabrication and structure optimization of membrane supports, and fundamentals of coupling reaction with separation in zeolite membrane reactor for water gas shift reaction. Through the fundamental study, the research teams have developed MFI zeolite membranes with good perm-selectivity for hydrogen over carbon dioxide, carbon monoxide and water vapor, and high stability for operation in syngas mixture containing 500 part per million hydrogen sulfide at high temperatures around 500°C. The research teams also developed a sulfur resistant catalyst for water gas shift reaction. Modeling and experimental studies on the zeolite membrane reactor for water gas shift reaction have demonstrated the effective use of the zeolite membrane reactor for production of high purity hydrogen stream.

  2. A Carbonaceous Membrane based on a Polymer of Intrinsic Microporosity (PIM-1) for Water Treatment.

    PubMed

    Kim, Hee Joong; Kim, Dong-Gyun; Lee, Kyuchul; Baek, Youngbin; Yoo, Youngjae; Kim, Yong Seok; Kim, Byoung Gak; Lee, Jong-Chan

    2016-10-26

    As insufficient access to clean water is expected to become worse in the near future, water purification is becoming increasingly important. Membrane filtration is the most promising technologies to produce clean water from contaminated water. Although there have been many studies to prepare highly water-permeable carbon-based membranes by utilizing frictionless water flow inside the carbonaceous pores, the carbon-based membranes still suffer from several issues, such as high cost and complicated fabrication as well as relatively low salt rejection. Here, we report for the first time the use of microporous carbonaceous membranes via controlled carbonization of polymer membranes with uniform microporosity for high-flux nanofiltration. Further enhancement of membrane performance is observed by O2 plasma treatment. The optimized membrane exhibits high water flux (13.30 LMH Bar(-1)) and good MgSO4 rejection (77.38%) as well as antifouling properties. This study provides insight into the design of microporous carbonaceous membranes for water purification.

  3. A Carbonaceous Membrane based on a Polymer of Intrinsic Microporosity (PIM-1) for Water Treatment

    NASA Astrophysics Data System (ADS)

    Kim, Hee Joong; Kim, Dong-Gyun; Lee, Kyuchul; Baek, Youngbin; Yoo, Youngjae; Kim, Yong Seok; Kim, Byoung Gak; Lee, Jong-Chan

    2016-10-01

    As insufficient access to clean water is expected to become worse in the near future, water purification is becoming increasingly important. Membrane filtration is the most promising technologies to produce clean water from contaminated water. Although there have been many studies to prepare highly water-permeable carbon-based membranes by utilizing frictionless water flow inside the carbonaceous pores, the carbon-based membranes still suffer from several issues, such as high cost and complicated fabrication as well as relatively low salt rejection. Here, we report for the first time the use of microporous carbonaceous membranes via controlled carbonization of polymer membranes with uniform microporosity for high-flux nanofiltration. Further enhancement of membrane performance is observed by O2 plasma treatment. The optimized membrane exhibits high water flux (13.30 LMH Bar‑1) and good MgSO4 rejection (77.38%) as well as antifouling properties. This study provides insight into the design of microporous carbonaceous membranes for water purification.

  4. A Carbonaceous Membrane based on a Polymer of Intrinsic Microporosity (PIM-1) for Water Treatment

    PubMed Central

    Kim, Hee Joong; Kim, Dong-Gyun; Lee, Kyuchul; Baek, Youngbin; Yoo, Youngjae; Kim, Yong Seok; Kim, Byoung Gak; Lee, Jong-Chan

    2016-01-01

    As insufficient access to clean water is expected to become worse in the near future, water purification is becoming increasingly important. Membrane filtration is the most promising technologies to produce clean water from contaminated water. Although there have been many studies to prepare highly water-permeable carbon-based membranes by utilizing frictionless water flow inside the carbonaceous pores, the carbon-based membranes still suffer from several issues, such as high cost and complicated fabrication as well as relatively low salt rejection. Here, we report for the first time the use of microporous carbonaceous membranes via controlled carbonization of polymer membranes with uniform microporosity for high-flux nanofiltration. Further enhancement of membrane performance is observed by O2 plasma treatment. The optimized membrane exhibits high water flux (13.30 LMH Bar−1) and good MgSO4 rejection (77.38%) as well as antifouling properties. This study provides insight into the design of microporous carbonaceous membranes for water purification. PMID:27782212

  5. Smart Fiber Membrane for pH-Induced Oil/Water Separation.

    PubMed

    Li, Jin-Jin; Zhou, Yin-Ning; Luo, Zheng-Hong

    2015-09-09

    Wastewater contaminated with oil or organic compounds poses threats to the environment and humans. Efficient separation of oil and water are highly desired yet still challenging. This paper reports the fabrication of a smart fiber membrane by depositing pH-responsive copolymer fibers on a stainless steel mesh through electrospinning. The cost-effective precursor material poly(methyl methacrylate)-block-poly(4-vinylpyridine) (PMMA-b-P4VP) was synthesized using copper(0)-mediated reversible-deactivation radical polymerization. The pH-responsive P4VP and the underwater oleophilic/hydrophilic PMMA confer the as-prepared membrane with switchable surface wettability toward water and oil. The three-dimensional network structure of the fibers considerably strengthens the oil/water wetting property of the membrane, which is highly desirable in the separation of oil and water mixtures. The as-prepared fiber membrane accomplishes gravity-driven pH-controllable oil/water separations. Oil selectively passes through the membrane, whereas water remains at the initial state; after the membrane is wetted with acidic water (pH 3), a reverse separation is realized. Both separations are highly efficient, and the membrane also exhibits switchable wettability after numerous cycles of the separation process. This cost-effective and easily mass-produced smart fiber membrane with excellent oil-fouling repellency has significant potential in practical applications, such as water purification and oil recovery.

  6. Trade Study for 9 kW Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Ungar, Gene; Stephan, Ryan

    2010-01-01

    Sublimators have been proposed and used in spacecraft for heat rejection. Sublimators are desirable heat rejection devices for short duration use because they can transfer large amounts of heat using little mass and are self-regulating devices. Sublimators reject heat into space by freezing water inside a porous substrate, allowing it to sublimate into vapor, and finally venting it into space. The state of the art thermal control system in orbiting spacecraft is a two loop, two fluid system. The external coolant loop typically uses a toxic single phase fluid that acquires heat from the spacecraft and rejects most of it via a radiator. The sublimator functions as a transient topper for orbiting spacecraft during day pass periods when radiator efficiency decreases. The sublimator interfaces with the internal loop through a built in heat exchanger. The internal loop fluid is non-toxic and is typically a propylene glycol and water solution with inhibitors to prevent corrosion with aluminum fins of the heat exchangers. Feedwater is supplied from a separate line to the sublimator to maintain temperature control of the cabin and vehicle hardware. Water membrane evaporators have been developed for spacecraft and spacesuits. They function similar to a sublimator but require a backpressure valve which could be actuated for this application with a simple fully open or fully closed modes. This technology would be applied to orbital thermal control (lunar or planetary). This paper details a trade study showing that evaporators would greatly reduce the consumable that is used, effectively wasted, by sublimators during start up and shut down during the topping phases of each orbit. State of the art for 9 kW sublimators reject about 870 W per kilogram of mass and 1150 W per liter of volume. If water with corrosion inhibitors is used the evaporators would be about 80% of the mass and volume of the equivalent system. The size and mass increases to about 110% if the internal fluid is

  7. Development of Ultrafiltration Membrane-Separation Technology for Energy-Efficient Water Treatment and Desalination Process

    SciTech Connect

    Yim, Woosoon; Bae, Chulsung

    2016-10-28

    The growing scarcity of fresh water is a major political and economic challenge in the 21st century. Compared to thermal-based distillation technique of water production, pressure driven membrane-based water purification process, such as ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), can offer more energy-efficient and environmentally friendly solution to clean water production. Potential applications also include removal of hazardous chemicals (i.e., arsenic, pesticides, organics) from water. Although those membrane-separation technologies have been used to produce drinking water from seawater (desalination) and non-traditional water (i.e., municipal wastewater and brackish groundwater) over the last decades, they still have problems in order to be applied in large-scale operations. Currently, a major huddle of membrane-based water purification technology for large-scale commercialization is membrane fouling and its resulting increases in pressure and energy cost of filtration process. Membrane cleaning methods, which can restore the membrane properties to some degree, usually cause irreversible damage to the membranes. Considering that electricity for creating of pressure constitutes a majority of cost (~50%) in membrane-based water purification process, the development of new nano-porous membranes that are more resistant to degradation and less subject to fouling is highly desired. Styrene-ethylene/butylene-styrene (SEBS) block copolymer is one of the best known block copolymers that induces well defined morphologies. Due to the polarity difference of aromatic styrene unit and saturated ethylene/butylene unit, these two polymer chains self-assemble each other and form different phase-separated morphologies depending on the ratios of two polymer chain lengths. Because the surface of SEBS is hydrophobic which easily causes fouling of membrane, incorporation of ionic group (e,g, sulfonate) to the polymer is necessary to reduces fouling

  8. Influence of cholesterol and ceramide VI on the structure of multilamellar lipid membranes at water exchange

    SciTech Connect

    Ryabova, N. Yu. Kiselev, M. A.; Balagurov, A. M.

    2010-05-15

    The structural changes in the multilamellar lipid membranes of dipalmitoylphosphatidylcholine (DPPC)/cholesterol and DPPC/ceramide VI binary systems during hydration and dehydration have been studied by neutron diffraction. The effect of cholesterol and ceramide on the kinetics of water exchange in DPPC membranes is characterized. Compared to pure DPPC, membranes of binary systems swell faster during hydration (with a characteristic time of {approx}30 min). Both compounds, ceramide VI and cholesterol, similarly affect the hydration of DPPC membranes, increasing the repeat distance due to the bilayer growth. However, in contrast to cholesterol, ceramide significantly reduces the thickness of the membrane water layer. The introduction of cholesterol into a DPPC membrane slows down the change in the parameters of the bilayer internal structure during dehydration. In the DPPC/ceramide VI/cholesterol ternary system (with a molar cholesterol concentration of 40%), cholesterol is partially released from the lamellar membrane structure into the crystalline phase.

  9. Photoresist-free patterning by mechanical abrasion of water-soluble lift-off resists and bare substrates: toward green fabrication of transparent electrodes.

    PubMed

    Printz, Adam D; Chan, Esther; Liong, Celine; Martinez, René S; Lipomi, Darren J

    2013-01-01

    This paper describes the fabrication of transparent electrodes based on grids of copper microwires using a non-photolithographic process. The process--"abrasion lithography"--takes two forms. In the first implementation (Method I), a water-soluble commodity polymer film is abraded with a sharp tool, coated with a conductive film, and developed by immersion in water. Water dissolves the polymer film and lifts off the conductive film in the unabraded areas. In the second implementation (Method II), the substrate is abraded directly by scratching with a sharp tool (i.e., no polymer film necessary). The abraded regions of the substrate are recessed and roughened. Following deposition of a conductive film, the lower profile and roughened topography in the abraded regions prevents mechanical exfoliation of the conductive film using adhesive tape, and thus the conductive film remains only where the substrate is scratched. As an application, conductive grids exhibit average sheet resistances of 17 Ω sq(-1) and transparencies of 86% are fabricated and used as the anode in organic photovoltaic cells in concert with the conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Compared to devices in which PEDOT:PSS alone serves as an anode, devices comprising grids of copper/nickel microwires and PEDOT:PSS exhibit lowered series resistance, which manifests in greater fill factor and power conversion efficiency. This simple method of forming micropatterns could find use in applications where cost and environmental impact should be minimized, especially as a potential replacement for the transparent electrode indium tin oxide (ITO) in thin-film electronics over large areas (i.e., solar cells) or as a method of rapid prototyping for laboratory-scale devices.

  10. Photoresist-Free Patterning by Mechanical Abrasion of Water-Soluble Lift-Off Resists and Bare Substrates: Toward Green Fabrication of Transparent Electrodes

    PubMed Central

    Printz, Adam D.; Chan, Esther; Liong, Celine; Martinez, René S.; Lipomi, Darren J.

    2013-01-01

    This paper describes the fabrication of transparent electrodes based on grids of copper microwires using a non-photolithographic process. The process—“abrasion lithography”—takes two forms. In the first implementation (Method I), a water-soluble commodity polymer film is abraded with a sharp tool, coated with a conductive film, and developed by immersion in water. Water dissolves the polymer film and lifts off the conductive film in the unabraded areas. In the second implementation (Method II), the substrate is abraded directly by scratching with a sharp tool (i.e., no polymer film necessary). The abraded regions of the substrate are recessed and roughened. Following deposition of a conductive film, the lower profile and roughened topography in the abraded regions prevents mechanical exfoliation of the conductive film using adhesive tape, and thus the conductive film remains only where the substrate is scratched. As an application, conductive grids exhibit average sheet resistances of 17 Ω sq–1 and transparencies of 86% are fabricated and used as the anode in organic photovoltaic cells in concert with the conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Compared to devices in which PEDOT:PSS alone serves as an anode, devices comprising grids of copper/nickel microwires and PEDOT:PSS exhibit lowered series resistance, which manifests in greater fill factor and power conversion efficiency. This simple method of forming micropatterns could find use in applications where cost and environmental impact should be minimized, especially as a potential replacement for the transparent electrode indium tin oxide (ITO) in thin-film electronics over large areas (i.e., solar cells) or as a method of rapid prototyping for laboratory-scale devices. PMID:24358321

  11. Exclusion and tortuosity effects for alcohol/water separation by zeolite-filled PDMS membranes. [polydimethylsiloxane

    SciTech Connect

    Te Hennepe, H.J.C.; Smolders, C.A.; Bargeman, D.; Mulder, M.H.V. )

    1991-01-01

    A resistance model has been developed to describe the increased pervaporation flux and selectivity for the separation of ethanol/water mixtures with silicalite-filled silicone rubber (SR) membranes as compared to unfilled SR membranes. The model interprets the increased component flux for ethanol in terms of an increasing ethanol permeability of the membrane. Membrane permeability is given as a function of rubber and silicalite permeabilities and of the silicalite content of the membrane. It is shown that silicalite permeability varies with the type of alcohol and the alcohol concentration in the feed mixture. In the series methanol, ethanol propanol, and butanol, the alcohol permeability of silicalite varies with the length of the alcohol molecule, the lowest permeability being found for butanol. In the presence of propanol an butanol, the silicalite particles are impermeable to water and obstruct water transport through the membrane.

  12. Adsorption of Small Molecules at Water--Hexane and Water--Membrane Interfaces

    NASA Astrophysics Data System (ADS)

    Wilson, Michael A.

    1996-03-01

    The interaction of solutes with aqueous interfaces plays a significant role in a variety of physical processes, including general anesthesia and atmospheric chemistry. We present molecular dynamics results for the transfer of several small solutes across water liquid--vapor, water--hexane and water--GMO bilayer membrane interfaces. (A. Pohorille and M. A. Wilson, J. Chem. Phys. (in press, 1995).)^, (A. Pohorille, P. CIeplak, and M. A. Wilson, Chem. Phys. (in press, 1995).) The free energies of transferring small polar molecules across the interface exhibit fairly deep minima while those of nonpolar molecules do not. This is due to a balance between nonelectrostatic contributions --- primarily the work required to create a cavity large enough to accommodate the solute --- and the solute--solvent electrostatic interactions.^1 The surface excess of solute is calculated and compared with experimental results from the Gibbs adsorption isotherm. The interfacial solubilities correlate with measured anesthetic potencies of these compounds, implying that the binding sites for anesthetics are located near the water--membrane interface.

  13. Excess chemical potential of small solutes across water--membrane and water--hexane interfaces

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Wilson, M. A.

    1996-01-01

    The excess chemical potentials of five small, structurally related solutes, CH4, CH3F, CH2F2, CHF3, and CF4, across the water-glycerol 1-monooleate bilayer and water-hexane interfaces were calculated at 300, 310, and 340 K using the particle insertion method. The excess chemical potentials of nonpolar molecules (CH4 and CF4) decrease monotonically or nearly monotonically from water to a nonpolar phase. In contrast, for molecules that possess permanent dipole moments (CH3F, CH2F, and CHF3), the excess chemical potentials exhibit an interfacial minimum that arises from superposition of two monotonically and oppositely changing contributions: electrostatic and nonelectrostatic. The nonelectrostatic term, dominated by the reversible work of creating a cavity that accommodates the solute, decreases, whereas the electrostatic term increases across the interface from water to the membrane interior. In water, the dependence of this term on the dipole moment is accurately described by second order perturbation theory. To achieve the same accuracy at the interface, third order terms must also be included. In the interfacial region, the molecular structure of the solvent influences both the excess chemical potential and solute orientations. The excess chemical potential across the interface increases with temperature, but this effect is rather small. Our analysis indicates that a broad range of small, moderately polar molecules should be surface active at the water-membrane and water-oil interfaces. The biological and medical significance of this result, especially in relation to the mechanism of anesthetic action, is discussed.

  14. [Evaluation of Goldmann applanation tonometer with thin membrane water manometer].

    PubMed

    Imamura, T; Imamura, T

    1994-06-01

    In order to evaluate the accuracy of applanation tonometry, we prepared a thin membrane water manometer with a 0.07 mm thick HEMA soft contact lens and measured the internal pressure using a Goldmann type applanation tonometer (KOWA HA-1). The results were as follows. When the inner rims of the fluorescein ring were in contact with each other, the measured pressure value was lower than the theoretical value by about 5-15 mmHg; the higher the internal pressure, the larger the difference from the theoretical value. When the applanated condition was observed carefully, a dark ring about 0.2 mm in width could be seen inside the fluorescein ring. By applanating until the inner rims of this dark ring contacted each other, the theoretical value and the measured value matched approximately. Observing the contact surface by means of specular reflection, the applanated surface was located inside the dark ring, maintaining a circular shape with distinct boundary and this plane showed concentric circles or map-like color interference fringes. Newton's rings appeared on the boundary between this light interference surface and the dark ring. So we concluded that the true applanated area existed inside the dark ring and the inner rim of the fluorescein ring did not constitute an indicator of the boundary of applanated area.

  15. Continuum simulations of water flow in carbon nanotube membranes

    NASA Astrophysics Data System (ADS)

    Popadić, A.; Walther, J. H.; Koumoutsakos, P.; Praprotnik, M.

    2014-08-01

    We propose the use of the Navier-Stokes equations subject to partial-slip boundary conditions to simulate water flows in Carbon NanoTube (CNT) membranes. The finite volume discretizations of the Navier-Stokes equations are combined with slip lengths extracted from molecular dynamics (MD) simulations to predict the pressure losses at the CNT entrance as well as the enhancement of the flow rate in the CNT. The flow quantities calculated from the present hybrid approach are in excellent agreement with pure MD results while they are obtained at a fraction of the computational cost. The method enables simulations of system sizes and times well beyond the present capabilities of MD simulations. Our simulations provide an asymptotic flow rate enhancement and indicate that the pressure losses at the CNT ends can be reduced by reducing their curvature. More importantly, our results suggest that flows at nanoscale channels can be described by continuum solvers with proper boundary conditions that reflect the molecular interactions of the liquid with the walls of the nanochannel.

  16. Continuum Simulations of Water Flow in Carbon Nanotube Membranes

    NASA Astrophysics Data System (ADS)

    Walther, J. H.; Popadic, A.; Koumoutsakos, P.; Praprotnik, M.

    2014-11-01

    We propose the use of the Navier-Stokes equations subject to partial-slip boundary conditions to simulate water flows in Carbon NanoTube (CNT) membranes. The finite volume discretisations of the Navier-Stokes equations are combined with slip lengths extracted from Molecular Dynamics (MD) simulations to predict the pressure losses at the CNT entrance as well as the enhancement of the flow rate in the CNT. The flow quantities calculated from the present hybrid approach are in excellent agreement with pure MD results while they are obtained at a fraction of the computational cost. The method enables simulations of system sizes and times well beyond the present capabilities of MD simulations. Our simulations provide an asymptotic flow rate enhancement and indicate that the pressure losses at the CNT ends can be reduced by reducing their curvature. More importantly, our results suggest that flows at nanoscale channels can be described by continuum solvers with proper boundary conditions that reflect the molecular interactions of the liquid with the walls of the nanochannel.

  17. Spacesuit Water Membrane Evaporator Integration with the ISS Extravehicular Mobility

    NASA Technical Reports Server (NTRS)

    Margiott, Victoria; Boyle, Robert

    2014-01-01

    NASA has developed a Solid Water Membrane Evaporation (SWME) to provide cooling for the next generation spacesuit. One approach to increasing the TRL of the system is to incorporate this hardware with the existing EMU. Several integration issues were addressed to support a potential demonstration of the SWME with the existing EMU. Systems analysis was performed to assess the capability of the SWME to maintain crewmember cooling and comfort as a replacement for sublimation. The materials of the SWME were reviewed to address compatibility with the EMU. Conceptual system placement and integration with the EMU via an EVA umbilical system to ensure crew mobility and Airlock egress were performed. A concept of operation for EVA use was identified that is compatible with the existing system. This concept is extensible as a means to provide cooling for the existing EMU. The cooling system of one of the EMUs on orbit has degraded, with the root cause undetermined. Should there be a common cause resident on ISS, this integration could provide a means to recover cooling capability for EMUs on orbit.

  18. Amphiphile grafted membranes for the separation of oil-in-water dispersions.

    PubMed

    Howarter, John A; Youngblood, Jeffrey P

    2009-01-01

    Perfluorinated end-capped polyethylene glycol surfactants were covalently attached to fritted glass membranes as a means to improve the separation of oil-in-water emulsions. Hexadecane was used as representative oil for the oil-in-water emulsions; membrane pore size was varied between 10 and 174 microm. Membranes were characterized with respect to contact angle, permeability of bulk fluids, and separation efficiency. Performance was compared to similar metrics applied to unmodified membranes. Modified membranes demonstrated static hexadecane contact angles which were higher than static water contact angles converse to their unmodified counterparts. The relative hydrophilicity and corresponding oleophobicity of the modified membranes resulted in greater water permeability as compared to hexadecane permeability. The presence of the perfluorinated constituent of the amphiphile retarded the flow of hexadecane. For modified membranes, suspended hexadecane coalesced at the membrane surface, was undercut by water, and floated to the surface such that only trace amounts of oil were present in the permeate. Therefore, modified membranes resisted fouling from oil due to the self-cleaning properties of the attached amphiphile.

  19. Osmotic versus conventional membrane bioreactors integrated with reverse osmosis for water reuse: Biological stability, membrane fouling, and contaminant removal.

    PubMed

    Luo, Wenhai; Phan, Hop V; Xie, Ming; Hai, Faisal I; Price, William E; Elimelech, Menachem; Nghiem, Long D

    2017-02-01

    This study systematically compares the performance of osmotic membrane bioreactor - reverse osmosis (OMBR-RO) and conventional membrane bioreactor - reverse osmosis (MBR-RO) for advanced wastewater treatment and water reuse. Both systems achieved effective removal of bulk organic matter and nutrients, and almost complete removal of all 31 trace organic contaminants investigated. They both could produce high quality water suitable for recycling applications. During OMBR-RO operation, salinity build-up in the bioreactor reduced the water flux and negatively impacted the system biological treatment by altering biomass characteristics and microbial community structure. In addition, the elevated salinity also increased soluble microbial products and extracellular polymeric substances in the mixed liquor, which induced fouling of the forward osmosis (FO) membrane. Nevertheless, microbial analysis indicated that salinity stress resulted in the development of halotolerant bacteria, consequently sustaining biodegradation in the OMBR system. By contrast, biological performance was relatively stable throughout conventional MBR-RO operation. Compared to conventional MBR-RO, the FO process effectively prevented foulants from permeating into the draw solution, thereby significantly reducing fouling of the downstream RO membrane in OMBR-RO operation. Accumulation of organic matter, including humic- and protein-like substances, as well as inorganic salts in the MBR effluent resulted in severe RO membrane fouling in conventional MBR-RO operation.

  20. Super square carbon nanotube network: a new promising water desalination membrane

    NASA Astrophysics Data System (ADS)

    Sun, Ligang; He, Xiaoqiao; Lu, Jian

    2016-04-01

    Super square (SS) carbon nanotube (CNT) networks, acting as a new kind of nanoporous membrane, manifest excellent water desalination performance. Nanopores in SS CNT network can efficiently filter NaCl from water. The water desalination ability of such nanoporous membranes critically depends on the pore diameter, permitting water molecule permeatration while salt ion obstruction. On the basis of the systematical analysis on the interaction among water permeability, salt concentration limit and pressure on the membranes, an empirical formula is developed to describe the relationship between pressure and concentration limit. In the meantime, the nonlinear relationship between pressure and water permeability is examined. Hence, by controlling pressure, optimal plan can be easily made to efficiently filter the saltwater. Moreover, steered molecular dynamics (MD) method uncovers bending and local buckling of SS CNT network that leads to salt ions passing through membranes. These important mechanical behaviours are neglected in most MD simulations, which may overestimate the filtration ability. Overall, water permeability of such material is several orders of magnitude higher than the conventional reverse osmosis membranes and several times higher than nanoporous graphene membranes. SS CNT networks may act as a new kind of membrane developed for water desalination with excellent filtration ability.

  1. Performance of Water Recirculation Loop Maintentance Components for the Advanced Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Rector, Tony; Peyton, Barbara; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2014-01-01

    Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessonslearned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

  2. Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Rector, Tony; Peyton, Barbara M.; Steele, John W.; Makinen, Janice; Bue, Grant C.; Campbell, Colin

    2014-01-01

    Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

  3. Membrane attack complex of complement: distribution of subunits between the hydrocarbon phase of target membranes and water.

    PubMed Central

    Podack, E R; Stoffel, W; Esser, A F; Müller-Eberhard, H J

    1981-01-01

    Membrane destruction by complement is effected by the membrane attack complex (MAC) which is the dimer of a fusion product of the complement proteins C5b, C6, C7, C8, and C9. Phospholipid bilayer vesicles were used as target membranes for the MAC and its intermediate complexes. The subunits of these membrane-bound complexes were explored as to their relative exposure to the hydrocarbon phase of the lipid bilayer and to water surrounding the lipid vesicles. Protein exposed to the aqueous phase was labeled with 125I; protein exposed to the hydrocarbon phase was labeled by using tritiated azido phospholipids and irradiation. Analysis of the membrane-bound MAC showed that subunits C5b, C8 beta, and C9 were exposed to the aqueous phase. The subunits C8 alpha-gamma and C9 were primarily in contact with the hydrocarbon phase. C6 and C7 were little exposed to either phase, suggesting that these proteins are inaccessible within the MAC. Analysis of the intermediate complexes showed that C5b was the subunit most exposed to water in membrane-bound C5b-7, and C5b and C8 beta were the water-exposed subunits in C5b-8. Subunit exposure to the hydrocarbon phase of the lipid bilayer changed during MAC assembly. Whereas all three subunits of C5b-7 carried the phospholipid photolabel; most of the label was bound to the C8 subunit in C5b-8 and to C9 in the MAC. It is proposed that contact with the hydrocarbon core of membranes is established by C5b-7 through each of its subunits, by C5b-8 through C8, and by the MAC through C8 and, particularly, C9. PMID:6270682

  4. Hydrogen production by high-temperature water splitting using electron-conducting membranes

    DOEpatents

    Lee, Tae H.; Wang, Shuangyan; Dorris, Stephen E.; Balachandran, Uthamalingam

    2004-04-27

    A device and method for separating water into hydrogen and oxygen is disclosed. A first substantially gas impervious solid electron-conducting membrane for selectively passing hydrogen is provided and spaced from a second substantially gas impervious solid electron-conducting membrane for selectively passing oxygen. When steam is passed between the two membranes at disassociation temperatures the hydrogen from the disassociation of steam selectively and continuously passes through the first membrane and oxygen selectively and continuously passes through the second membrane, thereby continuously driving the disassociation of steam producing hydrogen and oxygen.

  5. Temperature-modulated water filtration using microgel-functionalized hollow-fiber membranes.

    PubMed

    Menne, Daniel; Pitsch, Fee; Wong, John E; Pich, Andrij; Wessling, Matthias

    2014-05-26

    In the present work, we investigate the potential of aqueous polymer microgels in membrane technology, especially for filtration applications. The poly(N-vinylcaprolactam)-based microgels exhibit thermoresponsive behavior and were employed to coat hollow-fiber membranes used for micro- and ultrafiltration. We discuss the preparation of microgel-modified membranes (by "inside-out" as well as "outside-in" filtration in dead-end mode). The clean-water permeability and stability of these membranes was studied not only as a function of time, but also of temperature. The microgel-modified membranes exhibit a reversible thermoresponsive behavior whereby both the resistance and the retention increased with decreasing temperature.

  6. Mineral-Coated Polymer Membranes with Superhydrophilicity and Underwater Superoleophobicity for Effective Oil/Water Separation

    PubMed Central

    Chen, Peng-Cheng; Xu, Zhi-Kang

    2013-01-01

    Oil-polluted water is a worldwide problem due to the increasing industrial oily wastewater and the frequent oil spill accidents. Here, we report a novel kind of superhydrophilic hybrid membranes for effective oil/water separation. They were prepared by depositing CaCO3-based mineral coating on PAA-grafted polypropylene microfiltration membranes. The rigid mineral-coating traps abundant water in aqueous environment and forms a robust hydrated layer on the membrane pore surface, thus endowing the membranes with underwater superoleophobicity. Under the drive of either gravity or external pressure, the hybrid membranes separate a range of oil/water mixtures effectively with high water flux (>2000 L m−2 h−1), perfect oil/water separation efficiency (>99%), high oil breakthrough pressure (>140 kPa) and low oil fouling. The oil/water mixtures include not only free mixtures but also oil-in-water emulsions. Therefore, the mineral-coated membrane enables an efficient and energy-saving separation for various oil/water mixtures, showing attractive potential for practical oil/water separation. PMID:24072204

  7. Mineral-coated polymer membranes with superhydrophilicity and underwater superoleophobicity for effective oil/water separation.

    PubMed

    Chen, Peng-Cheng; Xu, Zhi-Kang

    2013-09-27

    Oil-polluted water is a worldwide problem due to the increasing industrial oily wastewater and the frequent oil spill accidents. Here, we report a novel kind of superhydrophilic hybrid membranes for effective oil/water separation. They were prepared by depositing CaCO3-based mineral coating on PAA-grafted polypropylene microfiltration membranes. The rigid mineral-coating traps abundant water in aqueous environment and forms a robust hydrated layer on the membrane pore surface, thus endowing the membranes with underwater superoleophobicity. Under the drive of either gravity or external pressure, the hybrid membranes separate a range of oil/water mixtures effectively with high water flux (>2000 L m(-2) h(-1)), perfect oil/water separation efficiency (>99%), high oil breakthrough pressure (>140 kPa) and low oil fouling. The oil/water mixtures include not only free mixtures but also oil-in-water emulsions. Therefore, the mineral-coated membrane enables an efficient and energy-saving separation for various oil/water mixtures, showing attractive potential for practical oil/water separation.

  8. Gravity-driven hybrid membrane for oleophobic-superhydrophilic oil-water separation and water purification by graphene.

    PubMed

    Yoon, Hyun; Na, Seung-Heon; Choi, Jae-Young; Latthe, Sanjay S; Swihart, Mark T; Al-Deyab, Salem S; Yoon, Sam S

    2014-10-07

    We prepared a simple, low-cost membrane suitable for gravity-driven oil-water separation and water purification. Composite membranes with selective wettability were fabricated from a mixture of aqueous poly(diallyldimethylammonium chloride) solution, sodium perfluorooctanoate, and silica nanoparticles. Simply dip-coating a stainless steel mesh using this mixture produced the oil-water separator. The contact angles (CAs) of hexadecane and water on the prepared composite membranes were 95 ± 2° and 0°, respectively, showing the oleophobicity and superhydrophilicity of the membrane. In addition, a graphene plug was stacked below the membrane to remove water-soluble organics by adsorption. As a result, this multifunctional device not only separates hexadecane from water, but also purifies water by the permeation of the separated water through the graphene plug. Here, methylene blue (MB) was removed as a demonstration. Membranes were characterized by high-resolution scanning electron microscopy (HRSEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy to elucidate the origin of their selective wettability.

  9. Effects of Pressure Reductions in a Proposed Siphon Water Lift System at St. Stephen Dam, South Carolina, on Mortality Rates of Juvenile American Shad and Blueback Herring.

    DTIC Science & Technology

    1998-09-01

    unlikely. Conducting additional mortality studies is recommended to refine predicted mortality rates . Measures should be taken to prevent juvenile fish...from entering the siphon lift system if excessive mortality rates are observed.

  10. Tensile deformation of polytetrafluoroethylene hollow fiber membranes used for water purification.

    PubMed

    Yonezu, Akio; Iio, Shouichi; Itonaga, Takehiro; Yamamura, Hiroshi; Chen, Xi

    2014-01-01

    The tensile deformation behavior of polytetrafluoroethylene (PTFE) hollow fiber membranes is studied. PTFE membranes at present have sub-micron pores with an open cell structure, which plays a critical role in water purification. One of the main challenges in water purification is that the pore structure becomes covered with biofouling, leading to blocked pores. To maintain the capacity for water purification, physical cleaning along with mechanical deformation is usually conducted. Thus, it is crucial to understand the mechanical properties, in particular the deformation behavior, of the membrane fibers. Using uniaxial tension experiments, we established a fundamental discrete model to describe the deformation behavior of a porous structure using a finite element method. The present model enables the prediction of the macroscopic deformation behavior of the membrane, by taking into account the changes of pore structure. The insight may be useful for porous membrane fabrication and provide insights for the reliable operation of water purification.

  11. Mechanically and structurally robust sulfonated block copolymer membranes for water purification applications

    NASA Astrophysics Data System (ADS)

    Yeo, J.; Kim, S. Y.; Kim, S.; Ryu, D. Y.; Kim, T.-H.; Park, M. J.

    2012-06-01

    The effective removal of ionic pollutants from contaminated water using negatively charged nanofiltration membranes is demonstrated. Block copolymers comprising polystyrene (PS) and partially hydrogenated polyisoprene (hPI) were synthesized by varying chain architectures. A one step procedure of cross-linking (hPI blocks) and sulfonation reactions (PS chains) was then carried out, which was revealed as an effective method to enhance mechanical integrity of membranes while hydrophilic sulfonated chains remain intact. In particular, the control of chain architecture allows us to create a synergetic effect on optimizing charge densities of the membrane, water permeability, and mechanical integrity under water purification conditions. The best performing membrane can almost completely (>99%) reject various divalent cations and also show NO3- rejection > 85% and Na+ rejection > 87%. Well defined nanostructures (tens of nanometers) as well as the periodically arranged water domains (a few nanometers) within hydrophilic phases of the hydrated membranes were confirmed by in situ neutron scattering experiments.

  12. FREIGHT CONTAINER LIFTING STANDARD

    SciTech Connect

    POWERS DJ; SCOTT MA; MACKEY TC

    2010-01-13

    This standard details the correct methods of lifting and handling Series 1 freight containers following ISO-3874 and ISO-1496. The changes within RPP-40736 will allow better reading comprehension, as well as correcting editorial errors.

  13. Aerodynamic Lifting Force.

    ERIC Educational Resources Information Center

    Weltner, Klaus

    1990-01-01

    Describes some experiments showing both qualitatively and quantitatively that aerodynamic lift is a reaction force. Demonstrates reaction forces caused by the acceleration of an airstream and the deflection of an airstream. Provides pictures of demonstration apparatus and mathematical expressions. (YP)

  14. Wind tower service lift

    DOEpatents

    Oliphant, David; Quilter, Jared; Andersen, Todd; Conroy, Thomas

    2011-09-13

    An apparatus used for maintaining a wind tower structure wherein the wind tower structure may have a plurality of legs and may be configured to support a wind turbine above the ground in a better position to interface with winds. The lift structure may be configured for carrying objects and have a guide system and drive system for mechanically communicating with a primary cable, rail or other first elongate member attached to the wind tower structure. The drive system and guide system may transmit forces that move the lift relative to the cable and thereby relative to the wind tower structure. A control interface may be included for controlling the amount and direction of the power into the guide system and drive system thereby causing the guide system and drive system to move the lift relative to said first elongate member such that said lift moves relative to said wind tower structure.

  15. High resolution neutron imaging of water in the polymer electrolyte fuel cell membrane

    SciTech Connect

    Mukherjee, Partha P; Makundan, Rangachary; Spendelow, Jacob S; Borup, Rodney L; Hussey, D S; Jacobson, D L; Arif, M

    2009-01-01

    Water transport in the ionomeric membrane, typically Nafion{reg_sign}, has profound influence on the performance of the polymer electrolyte fuel cell, in terms of internal resistance and overall water balance. In this work, high resolution neutron imaging of the Nafion{reg_sign} membrane is presented in order to measure water content and through-plane gradients in situ under disparate temperature and humidification conditions.

  16. Low-pressure membrane integrity tests for drinking water treatment: A review.

    PubMed

    Guo, H; Wyart, Y; Perot, J; Nauleau, F; Moulin, P

    2010-01-01

    Low-pressure membrane systems, including microfiltration (MF) and ultrafiltration (UF) membranes, are being increasingly used in drinking water treatments due to their high level of pathogen removal. However, the pathogen will pass through the membrane and contaminate the product if the membrane integrity is compromised. Therefore, an effective on-line integrity monitoring method for MF and UF membrane systems is essential to guarantee the regulatory requirements for pathogen removal. A lot of works on low-pressure membrane integrity tests have been conducted by many researchers. This paper provides a literature review about different low-pressure membrane integrity monitoring methods for the drinking water treatment, including direct methods (pressure-based tests, acoustic sensor test, liquid porosimetry, etc.) and indirect methods (particle counting, particle monitoring, turbidity monitoring, surrogate challenge tests). Additionally, some information about the operation of membrane integrity tests is presented here. It can be realized from this review that it remains urgent to develop an alternative on-line detection technique for a quick, accurate, simple, continuous and relatively inexpensive evaluation of low-pressure membrane integrity. To better satisfy regulatory requirements for drinking water treatments, the characteristic of this ideal membrane integrity test is proposed at the end of this paper.

  17. Produced water treatment by membranes: A review from a colloidal perspective.

    PubMed

    Dickhout, J M; Moreno, J; Biesheuvel, P M; Boels, L; Lammertink, R G H; de Vos, W M

    2017-02-01

    While the world faces an increased scarcity in fresh water supply, it is of great importance that water from industry and waste streams can be treated for re-use. One of the largest waste streams in the oil and gas industry is produced water. After the phase separation of oil and gas, the produced water is left. This mixture contains dissolved and dispersed hydrocarbons, surfactants, clay particles and salts. Before this water can be used for re-injection, irrigation or as industrial water, it has to be treated. Conventional filtration techniques such as multi media filters and cartridge filters, are able to remove the majority of the contaminants, but the smallest, stabilized oil droplets (<10μm) remain present in the treated water. In recent years, research has focused on membranes to remove these small oil droplets, because this technology requires no frequent replacement of filters and the water quality after treatment is better. Membranes however suffer from fouling by the contaminants in produced water, leading to a lower clean water flux and increased energy costs. Current research on produced water treatment by membranes is mainly focused on improving existing processes and developing fouling-resistant membranes. Multiple investigations have determined the importance of different factors (such as emulsion properties and operating conditions) on the fouling process, but understanding the background of fouling is largely absent. In this review, we describe the interaction between the membrane and a produced water emulsion from a colloidal perspective, with the aim to create a clear framework that can lead to much more detailed understanding of membrane fouling in produced water treatment. Better understanding of the complex interactions at the produced water/membrane interface is essential to achieve more efficient applications.

  18. Coriolis effects enhance lift on revolving wings.

    PubMed

    Jardin, T; David, L

    2015-03-01

    At high angles of attack, an aircraft wing stalls. This dreaded event is characterized by the development of a leading edge vortex on the upper surface of the wing, followed by its shedding which causes a drastic drop in the aerodynamic lift. At similar angles of attack, the leading edge vortex on an insect wing or an autorotating seed membrane remains robustly attached, ensuring high sustained lift. What are the mechanisms responsible for both leading edge vortex attachment and high lift generation on revolving wings? We review the three main hypotheses that attempt to explain this specificity and, using direct numerical simulations of the Navier-Stokes equations, we show that the latter originates in Coriolis effects.

  19. Sequential concentration of bacteria and viruses from marine waters using a dual membrane system.

    PubMed

    Abdelzaher, A M; Solo-Gabriele, H M; Wright, M E; Palmer, C J

    2008-01-01

    The ability to rapidly and effectively concentrate diverse microbes is an essential component for monitoring water quality at recreational beaches. The purpose of this study was to develop a 0.45 microm pore size dual membrane system, which can sequentially concentrate both viruses and bacteria. The top PVDF membrane was used to filter bacteria by physical straining while the bottom HA membrane retained viruses through adsorption. The recovery of this system was assessed using test organisms: enterococci and somatic coliphage. Volumes of 100 to 400 mL of unspiked and sewage-spiked beach water were filtered through both types of membranes. The PVDF membrane recovered statistically equivalent amounts of enterococci when compared to traditional membranes. All of the coliphage passed through the PVDF membrane, while 22% passed through the HA membrane. Increasing the volume from 100 to 400 mL did not significantly influence recoveries. Up to 35% of coliphage was eluted from the bottom membrane using beef extract solution. Rinsing bottom membranes with 0.5 mmol L(-1) H(2)S0(4) was found to deactivate somatic coliphage. This research demonstrates the potential of using a dual membrane adsorption system for the concentration of both bacteria and viruses from recreational beaches. A proposed bi-layer filtration system can be designed for simultaneous bacteria and virus filtration. Future experiments should focus on measurements utilizing additional bacteria and viruses.

  20. Addition of a Magnetite Layer onto a Polysulfone Water Treatment Membrane to Enhance Virus Removal

    NASA Astrophysics Data System (ADS)

    Raciny, Isabel

    The applicability of low-pressure membranes systems in distributed (point of use) water treatment is hindered by, among other things, their inability to remove potentially harmful viruses and ions via size exclusion. According to the USEPA and the Safe Drinking Water Act, drinking water treatment processes must be designed for 4-log virus removal. Batch experiments using magnetite nanoparticle (nano-Fe3O4) suspensions and water filtration experiments with Polysulfone (PSf) membranes coated with nano-Fe3O 4 were conducted to assess the removal of a model virus (bacteriophage MS2). The membranes were coated via a simple filtration protocol. Unmodified membranes were a poor adsorbent for MS2 bacteriophage with less than 0.5-log removal, whereas membranes coated with magnetite nanoparticles exhibited a removal efficiency exceeding 99.99% (4-log). Thus, a cartridge of PSf membranes coated with nano-Fe3O4 particles could be used to remove viruses from water. Such membranes showed negligible iron leaching into the filtrate, thus obviating concern about colored water. Further research is needed to reduce the loss of water flux caused by coating.

  1. Addition of a magnetite layer onto a polysulfone water treatment membrane to enhance virus removal.

    PubMed

    Raciny, I; Zodrow, K R; Li, D; Li, Q; Alvarez, P J J

    2011-01-01

    The applicability of low-pressure membranes systems in distributed (point of use) water treatment is hindered by, among other things, their inability to remove potentially harmful viruses and ions via size exclusion. According to the USEPA and the Safe Drinking Water Act, drinking water treatment processes must be designed for 4-log virus removal. Batch experiments using magnetite nanoparticle (nano-Fe3O4) suspensions and water filtration experiments with polysulfone membranes coated with nano-Fe3O4 were conducted to assess the removal of a model virus (bacteriophage MS2). The membranes were coated via a simple filtration protocol. Unmodified membranes were a poor adsorbent for MS2 bacteriophage with less than 0.5-log removal, whereas membranes coated with magnetite nanoparticles exhibited a removal efficiency exceeding 99.99% (4-log). Thus, a cartridge of PSf membranes coated with nano-Fe3O4 particles could be used to remove viruses from water. Such membranes showed negligible iron leaching into the filtrate, thus obviating concern about coloured water. Further research is needed to reduce the loss of water flux caused by coating.

  2. High-Performance Water Filtration Membranes using Surface Modification and New Materials

    NASA Astrophysics Data System (ADS)

    Huang, Xinwei

    Water scarcity is one of the most critical challenges faced by mankind and it is only getting worse due to source pollution and rising population. There is critical need for the development of water filtration membranes in order to treat polluted water and turn water from non-potable sources such as waste waster and ocean water into freshwater for human consumption and agricultural irrigation. Filtration Membranes are generally classified into four categories: microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), with decreasing pore size for rejecting different sized substances. Commercial filtration membranes are able to provide decent flux and rejection for their targeted applications. However, most of them suffer from fouling issues when the microorganisms and organic matter such as proteins and polysaccharides in the water source deposit onto the membrane surface, impeding the permeation of water and lowering the flux. Therefore, it is of high demand to develop membranes that are anti-fouling. Foulants such as protein particles adhere to the membrane surface via hydrophobic interactions. In order to minimize such effects, a typical way is to increase the hydrophilicity of the membrane by surface modification or by utilizing hydrophilic membrane materials. Foulants also tend to get trapped in the open "pores" on a rough membrane surface with ridges and valleys. It is then expected that a smoother membrane surface tend to lessen such effects. Incorporating antimicrobial properties into the membrane is also an effective way to reduce fouling as this inhibits the growth of microorganisms on the membrane surfaces. New materials are also used to fabricate membranes with improved performance. Conducting polymers have recently been discovered as a new category of membrane-making materials that are hydrophilic and low-fouling. A new type of polyaniline derivative has been used to fabricate UF membranes that demonstrate chlorine

  3. Preparation and evaluation of water-in-soybean oil-in-water emulsions by repeated premix membrane emulsification method using cellulose acetate membrane.

    PubMed

    Muhamad, Ida Idayu; Quin, Chang Hui; Selvakumaran, Suguna

    2016-04-01

    The purpose of this study was to investigate the preparation of formulated water- in-soybean oil-in-water emulsions by repeated premix membrane emulsification method using a cellulose acetate membrane. The effect of selective membrane emulsification process parameters (concentration of the emulsifiers, number of passes of the emulsions through the membrane and storage temperature) on the properties and stability of the developed emulsions were also investigated. 1, 3, 6, 8-pyrenetetrasulfonic acid tetrasodium salt (PTSA) was used as a hydrophilic model ingredient for the encapsulation of bioactive substances. W/O emulsions with 7 wt% (weight percentage) PGPR displays homogeneous and very fine dispersions, with the median diameter at 0.640 μm. Meanwhile, emulsions prepared by membrane emulsification (fine W/O/W) showed the highest stability at Tween 80 concentrations of 0.5 wt.% (weight percentage). It concluded that at 7 wt.% (weight percentage) PGPR concentration and 0.5 wt.% (weight percentage) Tween 80 concentrations, the most uniform particles with minimum mean size of oil drops (9.926 μm) were obtained after four passes through the membrane. Thus, cellulose acetate membrane can be used for preparing a stable W/O/W emulsions by repeated premix ME due to low cost and relatively easy to handle.

  4. Membrane Proteins Are Dramatically Less Conserved than Water-Soluble Proteins across the Tree of Life

    PubMed Central

    Sojo, Victor; Dessimoz, Christophe; Pomiankowski, Andrew; Lane, Nick

    2016-01-01

    Membrane proteins are crucial in transport, signaling, bioenergetics, catalysis, and as drug targets. Here, we show that membrane proteins have dramatically fewer detectable orthologs than water-soluble proteins, less than half in most species analyzed. This sparse distribution could reflect rapid divergence or gene loss. We find that both mechanisms operate. First, membrane proteins evolve faster than water-soluble proteins, particularly in their exterior-facing portions. Second, we demonstrate that predicted ancestral membrane proteins are preferentially lost compared with water-soluble proteins in closely related species of archaea and bacteria. These patterns are consistent across the whole tree of life, and in each of the three domains of archaea, bacteria, and eukaryotes. Our findings point to a fundamental evolutionary principle: membrane proteins evolve faster due to stronger adaptive selection in changing environments, whereas cytosolic proteins are under more stringent purifying selection in the homeostatic interior of the cell. This effect should be strongest in prokaryotes, weaker in unicellular eukaryotes (with intracellular membranes), and weakest in multicellular eukaryotes (with extracellular homeostasis). We demonstrate that this is indeed the case. Similarly, we show that extracellular water-soluble proteins exhibit an even stronger pattern of low homology than membrane proteins. These striking differences in conservation of membrane proteins versus water-soluble proteins have important implications for evolution and medicine. PMID:27501943

  5. Experimental evidence of rapid water transport through carbon nanotubes embedded in polymeric desalination membranes.

    PubMed

    Lee, Hee Dae; Kim, Hyo Won; Cho, Young Hoon; Park, Ho Bum

    2014-07-09

    As water molecules permeate ultrafast through carbon nanotubes (CNTs), many studies have prepared CNTs-based membranes for water purification as well as desalination, particularly focusing on high flux membranes. Among them, vertically aligned CNTs membranes with ultrahigh water flux have been successfully demonstrated for fundamental studies, but they lack scalability for bulk production and sufficiently high salt rejection. CNTs embedded in polymeric desalination membranes, i.e., polyamide thin-film composite (TFC) membranes, can improve water flux without any loss of salt rejection. This improved flux is achieved by enhancing the dispersion properties of CNTs in diamine aqueous solution and also by using cap-opened CNTs. Hydrophilic CNTs were prepared by wrapping CNT walls via bio-inspired surface modification using dopamine solution. Cap-opening of pristine CNTs is performed by using a thermo-oxidative process. As a result, hydrophilic, cap-opened CNTs-embedded polyamide TFC membranes are successfully prepared, which show much higher water flux than pristine polyamide TFC membrane. On the other hand, less-disperse, less cap-opened CNTs-embedded TFC membranes do not show any flux improvement and rather lead to lower salt rejection properties.

  6. Understanding the Effects of Compression and Constraints on Water Uptake of Fuel-Cell Membranes

    SciTech Connect

    Kusoglu, Ahmet; Kienitz, Brian L.; Weber, Adam Z.

    2011-01-01

    Accurate characterization of polymer-electrolyte fuel cells (PEFCs) requires understanding the impact of mechanical and electrochemical loads on cell components. An essential aspect of this relationship is the effect of compression on the polymer membrane?s water-uptake behavior and transport properties. However, there is limited information on the impact of physical constraints on membrane properties. In this paper, we investigate both theoretically and experimentally how the water uptake of Nafion membrane changes under external compression loads. The swelling of a compressed membrane is modeled by modifying the swelling pressure in the polymer backbone which relies on the changes in the microscopic volume of the polymer. The model successfully predicts the water content of the compressed membrane measured through in-situ swelling-compression tests and neutron imaging. The results show that external mechanical loads could reduce the water content and conductivity of the membrane, especially at lower temperatures, higher humidities, and in liquid water. The modeling framework and experimental data provide valuable insight for the swelling and conductivity of constrained and compressed membranes, which are of interest in electrochemical devices such as batteries and fuel cells.

  7. Pervaporation separation of ethanol-water mixtures using polyethylenimine composite membranes

    SciTech Connect

    Neidlinger, H.H.; Schissel, P.O.; Orth, R.A.

    1987-04-21

    The method of separating which consists of an ethanol-water mixture through a membrane film, comprising: providing a polymeric membrane film having a first and second side and consisting essentially of ethylenimine polymers supported on a microporous member and having a partially cross-linked and heat-cured surface, the cross-linking having been achieved by the use of a cross-linking agent consisting essentially of an isocyanate compound; providing an ethanol-water feed solution on the first side of the membrane film; applying a pressure differential between the first and the second sides of the membrane film sufficient to induce a diffusion flow of a permeate from the feed solution through the membrane; and recovering the permeate on the second side of the membrane film.

  8. Superhydrophobic membranes with ordered arrays of nanospiked microchannels for water desalination.

    PubMed

    Ma, Zeyu; Hong, Yan; Ma, Liyuan; Su, Ming

    2009-05-19

    Membrane distillation can desalinate seawater using low-grade heat energy or solar heat, but it has limited mass fluxes and membrane fouling issues. Glass membranes with integrated arrays of nanospiked microchannels and a narrow pore size distribution are made through a process that involves glass fiber drawing, dissolving template material from microchannels and differential chemical etching. After surface modification, superhydrophobic glass membranes with water contact angles of over 160 degrees are produced because of the formations of ordered arrays of spiked nanostructures. The superhydrophobic membrane has shown better antifouling ability and higher flux than those of existing polymer membranes, especially at high salt concentration, owing to its large pore diameter, straight pore shape, narrow pore size distribution, high chemical and thermal stabilities, and water-repelling ability.

  9. Use of ceragenins to create novel biofouling resistant water-treatment membranes.

    SciTech Connect

    Hibbs, Michael R.; Altman, Susan Jeanne; Feng, Yanshu; Savage, Paul B.; Pollard, Jacob; Sanchez, Andres L.; Fellows, Benjamin D.; Jones, Howland D. T.; McGrath, Lucas K.

    2008-12-01

    Scoping studies have demonstrated that ceragenins, when linked to water-treatment membranes have the potential to create biofouling resistant water-treatment membranes. Ceragenins are synthetically produced molecules that mimic antimicrobial peptides. Evidence includes measurements of CSA-13 prohibiting the growth of and killing planktonic Pseudomonas fluorescens. In addition, imaging of biofilms that were in contact of a ceragenin showed more dead cells relative to live cells than in a biofilm that had not been treated with a ceragenin. This work has demonstrated that ceragenins can be attached to polyamide reverse osmosis (RO) membranes, though work needs to improve the uniformity of the attachment. Finally, methods have been developed to use hyperspectral imaging with multivariate curve resolution to view ceragenins attached to the RO membrane. Future work will be conducted to better attach the ceragenin to the RO membranes and more completely test the biocidal effectiveness of the ceragenins on the membranes.

  10. Pervaporative removal of organics from water using hydrophobic membranes. Binary mixtures

    SciTech Connect

    Kujawski, W.

    2000-01-01

    Results of pervaporation experiments are presented for the separation of several polar and nonpolar organic solvents from their aqueous solutions. Three membranes were evaluated: a polydimethylsiloxane (PERVAP-1060) membrane, a PDMS ZSM-5 zeolite filled (PERVAP-1070) membrane, and a poly(ether-block-amide) (PEBAX-4033) membrane. The effect of feed composition on flux and selectivity was also investigated. Performance parameters of a given membrane depended both on the kind of the organic solvent and the feed composition. The PERVAP-1070 membrane exhibited the highest selectivity with a separation factor over 900 in contact with a water-butyl acetate mixture. Polar solvents like methanol were also preferentially separated from aqueous solutions, but the separation factors were close to those obtained from liquid-vapor equilibria data. Permeate fluxes of organics increased with increasing feed concentration. Synergetic effects between water and organics fluxes were also observed.

  11. Advancement in electrospun nanofibrous membranes modification and their application in water treatment.

    PubMed

    Nasreen, Shaik Anwar Ahamed Nabeela; Sundarrajan, Subramanian; Nizar, Syed Abdulrahim Syed; Balamurugan, Ramalingam; Ramakrishna, Seeram

    2013-09-30

    Water, among the most valuable natural resources available on earth, is under serious threat as a result of undesirable human activities: for example, marine dumping, atmospheric deposition, domestic, industrial and agricultural practices. Optimizing current methodologies and developing new and effective techniques to remove contaminants from water is the current focus of interest, in order to renew the available water resources. Materials like nanoparticles, polymers, and simple organic compounds, inorganic clay materials in the form of thin film, membrane or powder have been employed for water treatment. Among these materials, membrane technology plays a vital role in removal of contaminants due to its easy handling and high efficiency. Though many materials are under investigation, nanofibers driven membrane are more valuable and reliable. Synthetic methodologies applied over the modification of membrane and its applications in water treatment have been reviewed in this article.

  12. Advancement in Electrospun Nanofibrous Membranes Modification and Their Application in Water Treatment

    PubMed Central

    Nasreen, Shaik Anwar Ahamed Nabeela; Sundarrajan, Subramanian; Nizar, Syed Abdulrahim Syed; Balamurugan, Ramalingam; Ramakrishna, Seeram

    2013-01-01

    Water, among the most valuable natural resources available on earth, is under serious threat as a result of undesirable human activities: for example, marine dumping, atmospheric deposition, domestic, industrial and agricultural practices. Optimizing current methodologies and developing new and effective techniques to remove contaminants from water is the current focus of interest, in order to renew the available water resources. Materials like nanoparticles, polymers, and simple organic compounds, inorganic clay materials in the form of thin film, membrane or powder have been employed for water treatment. Among these materials, membrane technology plays a vital role in removal of contaminants due to its easy handling and high efficiency. Though many materials are under investigation, nanofibers driven membrane are more valuable and reliable. Synthetic methodologies applied over the modification of membrane and its applications in water treatment have been reviewed in this article. PMID:24957057

  13. Influence of zeolites in PDMS membranes. Pervaporation of water/alcohol mixtures

    SciTech Connect

    Vankelecom, I.F.J.; Depre, D.; De Beukelaer, S.; Uytterhoeven, J.B.

    1995-08-31

    A strong influence of the zeolite was found on the pervaporation of alcohol/water mixtures using filled PDMS membranes. In all cases, the zeolites reduced the swelling of the PDMS. Incorporation of the hydrophilic zeolite Y increased water fluxes, while ZSM-5 reduced both water and alcohol fluxes due to a partial retention of these molecules in the zeolite. For branched alcohols, the extreme importance of diffusion led to a strong dependency of selectivity and flux on temperature. Compared with commercially available PDMS membranes, better results were realized with the self-prepared membranes. 19 refs., 7 figs., 1 tab.

  14. Synthesis of PVDF ultrafiltration membranes supported on polyester fabrics for separation of organic matter from water

    NASA Astrophysics Data System (ADS)

    Mhlanga, Sabelo D.; Tshabalala, Tumelo G.; Nxumalo, Edward N.; Mamba, Bhekie B.

    2014-08-01

    Polyvinylidene flouride (PVDF) membranes supported on non-woven fabrics (NWF) of polyester are reported. The PVDF membranes were fabricated using the phase inversion method followed by modification of the active top layer of the PVDF thin film by adding polyvinylpyrolidone (PVP) into the cast solution. A PVDF resin was used with N- methyl-2-pyrrolidone (NMP) as a solvent. Sessile drop contact angle measurements and scanning electron microscopy (SEM) were used to study the physical properties of the membranes. Membrane rejection of humic acid was studied using a cross-flow membrane testing unit. The contact angle results revealed that the hydrophilicity of PVDF membranes increased as the PVP concentration was increased from 3 to 10 wt%. SEM analysis of the membranes revealed that the membrane pore sizes increased when PVP was added. AFM analysis also showed that membrane roughness changed when PVP was added. Total organic carbon (TOC) analysis of water samples spiked with humic acid was performed to test the rejection capacity of the membranes. Rejections of up to 97% were achieved for PVDF membranes supported on polyester NWF1, which had smaller thickness and higher permeability compared to polyester NWF2. The NWFs provided the high strength required for the membranes despite the modifications done on the PDVF surface and microstructure.

  15. Peptide Folding and Translocation Across the Water-Membrane Interface

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Chang, Sherwood (Technical Monitor)

    1997-01-01

    The ability of small peptides to organize at aqueous interfaces was examined by performing a series of large-scale, molecular dynamics computer simulations of several peptides composed of two amino acids, nonpolar leucine (L) and polar glutamine (Q). The peptides differed in size and sequence of the amino acids. Studies on dipeptides LL, LQ, QL and QQ were extended to two heptamers, LQQLLQL and LQLQLQL, designed to maximize interfacial stability of an alpha-helix and a beta-strand, respectively, by exposing polar side chains to water and nonpolar side chains to a nonpolar phase. Finally, a transition of an undecamer, composed entirely of leucine residues, from a disordered structure in water to an alpha-helix in a nonpolar phase representing the interior of the membrane was investigated. Complete folding of a peptide in solution was accomplished for the first time in computer simulations. The simulations revealed several basic principles governing the sequence-dependent organization of peptides at interfaces. Short peptides tend to accumulate at interfaces and acquire ordered structures, providing that they have a proper sequence of polar and nonpolar amino acids. The dominant factor determining the interfacial structure of peptides is the hydrophobic effect, which is manifested at aqueous interfaces as a tendency for polar and nonpolar groups of the solute to segregate into the aqueous and nonpolar phases, respectively. If peptides consist of nonpolar residue's only, they become inserted into the nonpolar phase. As demonstrated by the example of the leucine undecamer, such peptides fold into an alpha-helix as they partition into the nonpolar medium. The folding proceeds through an intermediate, called 3-10-helix, which remains in equilibrium with the alpha-helix. Once in the nonpolar environment, the peptides can readily change their orientation with respect to the interface from parallel to perpendicular, especially in response to local electric fields. The

  16. Membrane-associated aquaporin-1 facilitates osmotically driven water flux across the basolateral membrane of the thick ascending limb

    PubMed Central

    Cabral, Pablo D.

    2012-01-01

    The thick ascending limb of the loop of Henle (TAL) reabsorbs ∼30% of filtered NaCl but is impermeable to water. The observation that little water traverses the TAL indicates an absence of water channels at the apical membrane. Yet TAL cells swell when peritubular osmolality decreases indicating that water channels must be present in the basolateral side. Consequently, we hypothesized that the water channel aquaporin-1 (AQP1) facilitates water flux across the basolateral membrane of TALs. Western blotting revealed AQP1 expression in microdissected rat and mouse TALs. Double immunofluorescence showed that 95 ± 2% of tubules positive for the TAL-specific marker Tamm-Horsfall protein were also positive for AQP1 (n = 6). RT-PCR was used to demonstrate presence of AQP1 mRNA and the TAL-specific marker NKCC2 in microdissected TALs. Cell surface biotinylation assays showed that 23 ± 3% of the total pool of AQP1 was present at the TAL basolateral membrane (n = 7). To assess the functional importance of AQP1 in the basolateral membrane, we measured the rate of cell swelling initiated by decreasing peritubular osmolality as an indicator of water flux in microdissected TALs. Water flux was decreased by ∼50% in Aqp1 knockout mice compared with wild-types (4.0 ± 0.8 vs. 8.9 ± 1.7 fluorescent U/s, P < 0.02; n = 7). Furthermore, arginine vasopressin increased TAL AQP1 expression by 135 ± 17% (glycosylated) and 41 ± 11% (nonglycosylated; P < 0.01; n =5). We conclude that 1) the TAL expresses AQP1, 2) ∼23% of the total pool of AQP1 is localized to the basolateral membrane, 3) AQP1 mediates a significant portion of basolateral water flux, and 4) AQP1 is upregulated in TALs of rats infused with dDAVP. AQP1 could play an important role in regulation of TAL cell volume during changes in interstitial osmolality, such as during a high-salt diet or water deprivation. PMID:22674028

  17. Nonequilibrium molecular dynamics simulation of water transport through carbon nanotube membranes at low pressure.

    PubMed

    Wang, Luying; Dumont, Randall S; Dickson, James M

    2012-07-28

    Nonequilibrium molecular dynamics (NEMD) simulations are used to investigate pressure-driven water flow passing through carbon nanotube (CNT) membranes at low pressures (5.0 MPa) typical of real nanofiltration (NF) systems. The CNT membrane is modeled as a simplified NF membrane with smooth surfaces, and uniform straight pores of typical NF pore sizes. A NEMD simulation system is constructed to study the effects of the membrane structure (pores size and membrane thickness) on the pure water transport properties. All simulations are run under operating conditions (temperature and pressure difference) similar to a real NF processes. Simulation results are analyzed to obtain water flux, density, and velocity distributions along both the flow and radial directions. Results show that water flow through a CNT membrane under a pressure difference has the unique transport properties of very fast flow and a non-parabolic radial distribution of velocities which cannot be represented by the Hagen-Poiseuille or Navier-Stokes equations. Density distributions along radial and flow directions show that water molecules in the CNT form layers with an oscillatory density profile, and have a lower average density than in the bulk flow. The NEMD simulations provide direct access to dynamic aspects of water flow through a CNT membrane and give a view of the pressure-driven transport phenomena on a molecular scale.

  18. Nonequilibrium molecular dynamics simulation of water transport through carbon nanotube membranes at low pressurea)

    NASA Astrophysics Data System (ADS)

    Wang, Luying; Dumont, Randall S.; Dickson, James M.

    2012-07-01

    Nonequilibrium molecular dynamics (NEMD) simulations are used to investigate pressure-driven water flow passing through carbon nanotube (CNT) membranes at low pressures (5.0 MPa) typical of real nanofiltration (NF) systems. The CNT membrane is modeled as a simplified NF membrane with smooth surfaces, and uniform straight pores of typical NF pore sizes. A NEMD simulation system is constructed to study the effects of the membrane structure (pores size and membrane thickness) on the pure water transport properties. All simulations are run under operating conditions (temperature and pressure difference) similar to a real NF processes. Simulation results are analyzed to obtain water flux, density, and velocity distributions along both the flow and radial directions. Results show that water flow through a CNT membrane under a pressure difference has the unique transport properties of very fast flow and a non-parabolic radial distribution of velocities which cannot be represented by the Hagen-Poiseuille or Navier-Stokes equations. Density distributions along radial and flow directions show that water molecules in the CNT form layers with an oscillatory density profile, and have a lower average density than in the bulk flow. The NEMD simulations provide direct access to dynamic aspects of water flow through a CNT membrane and give a view of the pressure-driven transport phenomena on a molecular scale.

  19. Quaternized poly (styrene-co-vinylbenzyl chloride) anion exchange membranes for alkaline water electrolysers

    NASA Astrophysics Data System (ADS)

    Vengatesan, S.; Santhi, S.; Jeevanantham, S.; Sozhan, G.

    2015-06-01

    In this study, poly (ST-co-VBC) based anion exchange membranes with different styrene to VBC ratios (1: 0.16, 1: 0.33 and 1: 1) have been prepared via chloromethylation-free synthetic route using aromatic vinyl monomers. The synthesized co-polymers are identified by FTIR and 1H-NMR analysis. Hydroxide (OH-) ion conductivity of the anion exchange membrane with styrene to VBC ratio of 1: 0.33 is as high as 6.8 × 10-3 S cm-1 in de-ionised water at 25 °C. The membrane also acquires the ion-exchange capacity of 2.14 meq. g-1, and the water uptake of 127%. Membrane-electrode-assembly (MEA) using the anion exchange membrane and Ni - foam catalyst demonstrate the current density of 40 mA cm-2 at 2.3 V in a water electrolyser cell.

  20. Separating Oil-Water Nanoemulsions using Flux-Enhanced Hierarchical Membranes

    PubMed Central

    Solomon, Brian R.; Hyder, Md. Nasim; Varanasi, Kripa K.

    2014-01-01

    Membranes that separate oil-water mixtures based on contrasting wetting properties have recently received significant attention. Separation of nanoemulsions, i.e. oil-water mixtures containing sub-micron droplets, still remains a key challenge. Tradeoffs between geometric constraints, high breakthrough pressure for selectivity, high flux, and mechanical durability make it challenging to design effective membranes. In this paper, we fabricate a hierarchical membrane by the phase inversion process that consists of a nanoporous separation skin layer supported by an integrated microporous layer. We demonstrate the separation of water-in-oil emulsions well below 1 μm in size. In addition, we tune the parameters of the hierarchical membrane fabrication to control the skin layer thickness and increase the total flux by a factor of four. These simple yet robust hierarchical membranes with engineered wetting characteristics show promise for large-scale, efficient separation systems. PMID:24980852

  1. Synthesis of superhydrophobic alumina membrane: Effects of sol-gel coating, steam impingement and water treatment

    NASA Astrophysics Data System (ADS)

    Ahmad, N. A.; Leo, C. P.; Ahmad, A. L.

    2013-11-01

    Ceramic membranes possess natural hydrophilicity thus tending to absorb water droplets. The absorption of water molecules on membrane surface reduces their application in filtration, membrane distillation, osmotic evaporation and membrane gas absorption. Fluoroalkylsilane (FAS) grafting allows the conversion of hydrophilic ceramic membranes into superhydrophobic thin layer, but it usually introduces a great increment of mass transfer resistance. In this study, superhydrophobic alumina membranes were synthesized by dip coating alumina support into sol-gel and grafted with the fluoroalkylsilane (FAS) named (heptadecafluoro-1,1,2,2-tetra hydrodecyl) triethoxysilane. Steam impingement and water treatment acted as additional steps to generate surface roughness on sol-gel and most importantly to reduce mass transfer resistance. Superhydrophobic alumina membrane with high water contact angle (158.4°) and low resistance (139.5 ± 24.9 G m-1) was successfully formed when the alumina membrane was dip coated into sol-gel for 7 s, treated with steam impingement for 1 min and immersed in hot water at 100 °C. However, the mass transfer resistance was greatly induced to 535.6 ± 23.5 G m-1 when the dip coating time was increased to 60 s. Long dip coating time contributes more on the blockage of porous structure rather than creates a thin film on the top of membrane surface. Reducing the pore size and porosity significantly due to increase of coating molecules deposited on the membrane. Steam impingement for 1 min promoted the formation of cones and valleys on the sol-gel, but the macro-roughness was destroyed when the steam impingement duration was extended to more than 3 min. The immersions of membranes into hot water at temperatures higher than 60 °C encouraged the formation of boehmite which enhances the formation of additional roughness and enlarges pore size greatly. Thus, this work showed that the formation of superhydrophobic alumina membrane with low resistance is

  2. Improving irrigation efficiency of sandy soils by subsurface water retaining membranes

    NASA Astrophysics Data System (ADS)

    Guber, Andrey; Smucker, Alvin; Berhanu, Samrawi

    2014-05-01

    Sustainable crop production in sandy soils is challenging due to low soil water holding capacity and high water permeability. The subsurface water retention technology (SWRT) is a relatively new long-term approach that offers precision control of water and nutrients in the root zone. However, multiple design of SWRT membrane configurations and spatial distributions require more modeling for best application in arid regions with relevant irrigation methods. The objective of this study was to define optimal geometric parameters of the SWRT membranes and the most accurate irrigation rates for corn production in sandy soils. HYDRUS-2D model, that describes two-dimensional water flow in unsaturated soil, was calibrated and validated on data in a large sand-filled lysimeter with SWRT membranes installed at different depths with different aspect ratios. The model adequately reproduced soil water content dynamics measured at 12 locations inside the sand profile. Then HYDRUS-2D simulations were repeated with different SWRT installation depths and aspect ratios. The installation depths in these simulations were 20 cm, 40 cm, and 60 cm, while the aspect ratios were 2:1, 3:1, 5:1 and 10:1. The results of simulations confirmed water holding capacity of the soil can be differentially controlled by aspect ratios of SWRT membranes. SWRT membranes with an aspect ratio of 2:1 substantially increased soil water content at 20-cm soil layer above the membrane, and this effect diminished with increasing aspect ratio of the membrane. Installation depth within the soil profile had no significant effect on water loss. The HYDRUS-2D simulations were repeated with SWRT installed at depth of 20 cm for sprinkle, surface drip and subsurface drip irrigation. Corn irrigation was triggered at pressure head of -30cm at a depth of 15 cm for all irrigation techniques. Simulated water losses by deep infiltration in sands without SWRT membranes approached 60% with approximately 15% losses when SWRT

  3. Nanofiltration of Mine Water: Impact of Feed pH and Membrane Charge on Resource Recovery and Water Discharge

    PubMed Central

    Mullett, Mark; Fornarelli, Roberta; Ralph, David

    2014-01-01

    Two nanofiltration membranes, a Dow NF 270 polyamide thin film and a TriSep TS 80 polyamide thin film, were investigated for their retention of ionic species when filtering mine influenced water streams at a range of acidic pH values. The functional iso-electric point of the membranes, characterized by changes in retention over a small pH range, were examined by filtering solutions of sodium sulphate. Both membranes showed changes in retention at pH 3, suggesting a zero net charge on the membranes at this pH. Copper mine drainage and synthetic solutions of mine influenced water were filtered using the same membranes. These solutions were characterized by pH values within 2 and 5, thus crossing the iso-electric point of both membranes. Retention of cations was maximized when the feed solution pH was less than the iso-electric point of the membrane. In these conditions, the membrane has a net positive charge, reducing the transmission rate of cations. From the recoveries of a range of cations, the suitability of nanofiltration was discussed relative to the compliance with mine water discharge criteria and the recovery of valuable commodity metals. The nanofiltration process was demonstrated to offer advantages in metal recovery from mine waste streams, concomitantly enabling discharge criteria for the filtrate disposal to be met. PMID:24957170

  4. Nanofiltration of Mine Water: Impact of Feed pH and Membrane Charge on Resource Recovery and Water Discharge.

    PubMed

    Mullett, Mark; Fornarelli, Roberta; Ralph, David

    2014-03-27

    Two nanofiltration membranes, a Dow NF 270 polyamide thin film and a TriSep TS 80 polyamide thin film, were investigated for their retention of ionic species when filtering mine influenced water streams at a range of acidic pH values. The functional iso-electric point of the membranes, characterized by changes in retention over a small pH range, were examined by filtering solutions of sodium sulphate. Both membranes showed changes in retention at pH 3, suggesting a zero net charge on the membranes at this pH. Copper mine drainage and synthetic solutions of mine influenced water were filtered using the same membranes. These solutions were characterized by pH values within 2 and 5, thus crossing the iso-electric point of both membranes. Retention of cations was maximized when the feed solution pH was less than the iso-electric point of the membrane. In these conditions, the membrane has a net positive charge, reducing the transmission rate of cations. From the recoveries of a range of cations, the suitability of nanofiltration was discussed relative to the compliance with mine water discharge criteria and the recovery of valuable commodity metals. The nanofiltration process was demonstrated to offer advantages in metal recovery from mine waste streams, concomitantly enabling discharge criteria for the filtrate disposal to be met.

  5. Use of semipermeable membrane devices (SPMDs) in petroleum polluted waters

    USGS Publications Warehouse

    Alvarez, David A.

    2010-01-01

    Passive samplers, in particular semipermeable membrane devices (SPMDs), can be used in monitoring petroleum spills. This document is intended to provide a brief discussion of issues surrounding the use and capabilities of the SPMD.

  6. Coalification process waste water reusability: separation of organics by membranes

    SciTech Connect

    Bhattacharyya, D.; Kermode, R.I.; Dickinson, R.L.

    1983-02-01

    The overall objective of this investigation is to provide a critical evaluation of the current information concerning coal-gasification wastewaters and to establish experimentally the extent of separation of phenolics and polynuclear aromatic hydrocarbons (from single and multi-solute synthetic systems) by low-and high-pressure composite membranes. The compounds selected for experimental investigation were: phenol, O-cresol, 2,3-dimethylphenol, catechol, resorcinol, 2-naphthol, naphthalene, and indole. The development of membrane separation processes is gaining considerable importance because of the feasibility of simultaneous removal of organics and inorganic dissolved solids. Cellulose-acetate membranes developed for desalination processes show no rejection of phenolics; however, recently developed thin-film, noncellulosic composite membranes (even at low-pressure operation) may be useful in gasification wastewater reuse schemes. 24 references, 11 figures, 5 tables.

  7. Treating Coalbed Natural Gas Produced Water for Beneficial Use By MFI Zeolite Membranes

    SciTech Connect

    Robert Lee; Liangxiong Li

    2008-03-31

    Desalination of brines produced from oil and gas fields is an attractive option for providing potable water in arid regions. Recent field-testing of subsurface sequestration of carbon dioxide for climate management purposes provides new motivation for optimizing efficacy of oilfield brine desalination: as subsurface reservoirs become used for storing CO{sub 2}, the displaced brines must be managed somehow. However, oilfield brine desalination is not economical at this time because of high costs of synthesizing membranes and the need for sophisticated pretreatments to reduce initial high TDS and to prevent serious fouling of membranes. In addition to these barriers, oil/gas field brines typically contain high concentrations of multivalent counter cations (eg. Ca{sup 2+} and SO{sub 4}{sup 2-}) that can reduce efficacy of reverse osmosis (RO). Development of inorganic membranes with typical characteristics of high strength and stability provide a valuable option to clean produced water for beneficial uses. Zeolite membranes have a well-defined subnanometer pore structure and extreme chemical and mechanical stability, thus showing promising applicability in produced water purification. For example, the MFI-type zeolite membranes with uniform pore size of {approx}0.56 nm can separate ions from aqueous solution through a mechanism of size exclusion and electrostatic repulsion (Donnan exclusion). Such a combination allows zeolite membranes to be unique in separation of both organics and electrolytes from aqueous solutions by a reverse osmosis process, which is of great interest for difficult separations, such as oil-containing produced water purification. The objectives of the project 'Treating Coalbed Natural Gas Produced Water for Beneficial Use by MFI Zeolite Membranes' are: (1) to conduct extensive fundamental investigations and understand the mechanism of the RO process on zeolite membranes and factors determining the membrane performance, (2) to improve the

  8. HIGH PERMEABILITY MEMBRANES FOR THE DEHYDRATION OF LOW WATER CONTENT ETHANOL BY PERVAPORATION

    EPA Science Inventory

    Energy efficient dehydration of low water content ethanol is a challenge for the sustainable production of fuel-grade ethanol. Pervaporative membrane dehydration using a recently developed hydrophilic polymer membrane formulation consisting of a cross-linked mixture of poly(allyl...

  9. Mixed reverse micelles facilitated downstream processing of lipase involving water-oil-water liquid emulsion membrane.

    PubMed

    Bhowal, Saibal; Priyanka, B S; Rastogi, Navin K

    2014-01-01

    Our earlier work for the first time demonstrated that liquid emulsion membrane (LEM) containing reverse micelles could be successfully used for the downstream processing of lipase from Aspergillus niger. In the present work, we have attempted to increase the extraction and purification fold of lipase by using mixed reverse micelles (MRM) consisting of cationic and nonionic surfactants in LEM. It was basically prepared by addition of the internal aqueous phase solution to the organic phase followed by the redispersion of the emulsion in the feed phase containing enzyme, which resulted in globules of water-oil-water (WOW) emulsion for the extraction of lipase. The optimum conditions for maximum lipase recovery (100%) and purification fold (17.0-fold) were CTAB concentration 0.075 M, Tween 80 concentration 0.012 M, at stirring speed of 500 rpm, contact time 15 min, internal aqueous phase pH 7, feed pH 9, KCl concentration 1 M, NaCl concentration 0.1 M, and ratio of membrane emulsion to feed volume 1:1. Incorporation of the nonionic surfactant (e.g., Tween 80) resulted in remarkable improvement in the purification fold (3.1-17.0) of the lipase. LEM containing a mixture of nonionic and cationic surfactants can be successfully used for the enhancement in the activity recovery and purification fold during downstream processing of enzymes/proteins.

  10. Osmotically-driven membrane processes for water reuse and energy recovery

    NASA Astrophysics Data System (ADS)

    Achilli, Andrea

    Osmotically-driven membrane processes are an emerging class of membrane separation processes that utilize concentrated brines to separate liquid streams. Their versatility of application make them an attractive alternative for water reuse and energy production/recovery. This work focused on innovative applications of osmotically-driven membrane processes. The novel osmotic membrane bioreactor (OMBR) system for water reuse was presented. Experimental results demonstrated high sustainable flux and relatively low reverse diffusion of solutes from the draw solution into the mixed liquor. Membrane fouling was minimal and controlled with osmotic backwashing. The OMBR system was found to remove greater than 99% of organic carbon and ammonium-nitrogen. Forward osmosis (FO) can employ different draw solution in its process. More than 500 inorganic compounds were screened as draw solution candidates, the desktop screening process resulted in 14 draw solutions suitable for FO applications. The 14 draw solutions were then tested in the laboratory to evaluate water flux and reverse salt diffusion through the membrane. Results indicated a wide range of water flux and reverse salt diffusion depending on the draw solution utilized. Internal concentration polarization was found to lower both water flux and reverse salt diffusion by reducing the draw solution concentration at the interface between the support and dense layer of the membrane. A small group of draw solutions was found to be most suitable for FO processes with currently available FO membranes. Another application of osmotically-driven membrane processes is pressure retarded osmosis (PRO). PRO was investigated as a viable source of renewable energy. A PRO model was developed to predict water flux and power density under specific experimental conditions. The predictive model was tested using experimental results from a bench-scale PRO system. Previous investigations of PRO were unable to verify model predictions due to

  11. UNDERSTANDING THE EFFECT OF DYNAMIC FEED CONDITIONS ON WATER RECOVERY FROM IC ENGINE EXHAUST BY CAPILLARY CONDENSATION WITH INORGANIC MEMBRANES

    SciTech Connect

    DeBusk, Melanie Moses; Bischoff, Brian L; Hunter, James A; Klett, James William; Nafziger, Eric J; Daw, C Stuart

    2014-01-01

    An inorganic membrane water recovery concept is evaluated as a method to recovering water from the exhaust of an internal combustion engine. Integrating the system on-board a vehicle would create a self-sustaining water supply that would make engine water injection technologies consumer transparent . In laboratory experiments, water recovery from humidified air was measured to evaluate how different operating parameters affect the membrane system s efficiency. The observed impact of transmembrane pressure and gas flow rate suggest that gas residence time is more important than water flux through the membrane. Heat transfer modeling suggests that increasing membrane length can be used to improve efficiency and allow greater flow per membrane, an important parameter for practical applications where space is limited. The membrane water recovery concept was also experimentally validated by extracting water from diesel exhaust coming from a stationary generator. The insight afforded by these studies provides a basis for developing improved membrane designs that balance both efficiency and cost.

  12. Design and development of new polymer membranes for water filtration applications

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Evan S.

    The overall objective of this thesis research is to design and develop new polymer membranes that overcome several limitations that exist in conventional water filtration membranes. Two separate research thrusts were explored. In the first study, new polymer coatings for water ultrafiltration (UF) membranes were developed to reduce protein adsorption and fouling. Fifteen different functional monomers were synthesized, coated, and polymerized onto UF supports. Their resistance to protein adsorption and membrane protein fouling were then examined. For the first time, certain simple quaternary phosphonium- and ammonium-based polymer coatings were shown to be effective at resisting protein adsorption and membrane fouling. The second research objective is to design and develop new nanoporous polymer membranes with uniform, sub-1-nanometer pores for water purification via a size-exclusion mechanism. Cross-linkable lyotropic liquid crystals (LLCs) were examined due to their ability to self-organize into regular, porous nanostructures when mixed with water. Photo-radical cross-linking of these LLC assemblies resulted in robust polymer membranes with uniform nanopores. A 1st-generation LLC membrane containing a type I bicontinuous cubic (QI) phase structure and 3D-interconnected nanopores was made using a gemini phosphonium monomer. Comprehensive water filtration experiments and the use of a modified Donnan-steric pore model (DSPM) showed that this membrane has an effective pore diameter of 0.90 nm with a monodisperse pore size. It can remove small organic and inorganic solutes better than a nanofiltration (NF) membrane and almost as well as a reverse osmosis (RO) membrane. It also resisted chlorine degradation and protein adsorption. However, this monomer is difficult and expensive to synthesis and process. A 2 nd-generation QI-phase gemini ammonium-based monomer was developed to overcome these issues. Two homologues were found to form Q I-phase. Water transport studies

  13. Pilot Scale Water Gas Shift - Membrane Device for Hydrogen from Coal

    SciTech Connect

    Barton, Tom

    2013-06-30

    The objectives of the project were to build pilot scale hydrogen separation systems for use in a gasification product stream. This device would demonstrate fabrication and manufacturing techniques for producing commercially ready facilities. The design was a 2 lb/day hydrogen device which included composite hydrogen separation membranes, a water gas shift monolith catalyst, and stainless steel structural components. Synkera Technologies was to prepare hydrogen separation membranes with metallic rims, and to adjust the alloy composition in their membranes to a palladium-gold composition which is sulfur resistant. Chart was to confirm their brazing technology for bonding the metallic rims of the composite membranes to their structural components and design and build the 2 lbs/day device incorporating membranes and catalysts. WRI prepared the catalysts and completed the testing of the membranes and devices on coal derived syngas. The reactor incorporated eighteen 2'' by 7'' composite palladium alloy membranes. These membranes were assembled with three stacks of three paired membranes. Initial vacuum testing and visual inspection indicated that some membranes were cracked, either in transportation or in testing. During replacement of the failed membranes, while pulling a vacuum on the back side of the membranes, folds were formed in the flexible composite membranes. In some instances these folds led to cracks, primarily at the interface between the alumina and the aluminum rim. The design of the 2 lb/day device was compromised by the lack of any membrane isolation. A leak in any membrane failed the entire device. A large number of tests were undertaken to bring the full 2 lb per day hydrogen capacity on line, but no single test lasted more than 48 hours. Subsequent tests to replace the mechanical seals with brazing have been promising, but the technology remains promising but not proven.

  14. Hydrogen production by water dissociation using ceramic membranes - annual report for FY 2008.

    SciTech Connect

    Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y.; Picciolo, J. J.; Energy Systems

    2009-03-25

    The objective of this project is to develop dense ceramic membranes that, without using an external power supply or circuitry, can produce hydrogen via coal/coal gas-assisted water dissociation. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen by means of OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.

  15. Hydrogen production by water dissociation using ceramic membranes. Annual report for FY 2009.

    SciTech Connect

    Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y.; Picciolo, J. J.; Energy Systems

    2010-04-20

    The objective of this project is to develop dense ceramic membranes that can produce hydrogen via coal/coal gas-assisted water dissociation without using an external power supply or circuitry. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen by means of OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.

  16. Hydrogen production by water dissociation using ceramic membranes - annual report for FY 2010.

    SciTech Connect

    Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y.; Picciolo, J. J.

    2011-03-14

    The objective of this project is to develop dense ceramic membranes that can produce hydrogen via coal/coal gas-assisted water dissociation without using an external power supply or circuitry. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen using OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.

  17. Development of implantable hemodialysis system using PES membranes with high water-permeability.

    PubMed

    To, N; Sanada, I; Ito, H; Morita, S; Kanno, Y; Miki, N

    2015-08-01

    This paper presents development of high water-permeable dialysis membranes. We proposed the system that does not use dialysis fluid for the implantable micro dialysis treatment and development of such membranes is crucial. We developed micro dialysis system composed by nanoporous membranes and microfluidic channels in our prior work. The membranes were made of nanoporous polyethersulfone (PES), which was not water-permeable. By not using dialysate, our device can be simplified because the pumps and storage tanks for the dialysis fluid are not necessary. This treatment is termed as hemofiltration. We measured the water permeability of PES membrane with respect to the concentrations of the PES, the additives, and the solvents in the casting solution. We could find the membranes with sufficiently high water permeability through in vitro experiments using a syringe pomp and whole cow blood, and the membrane had enough mechanical strength. We conducted experiments with multi-layered device in in vitro and in vivo using rats, where the system was connected to the vein and artery. We successfully collected the filtrate beyond target line, which was set by a medical doctor, without any leakage of blood from the device. The results verified that the filtration device can be scaled-up by increasing a number of the layer. We connected the device to a rat for 5h. It was verified the device maintained almost constant water permeability beyond our target line.

  18. 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.

  19. Computational and experimental platform for understanding and optimizing water flux and salt rejection in nanoporous membranes.

    SciTech Connect

    Rempe, Susan B.

    2010-09-01

    Affordable clean water is both a global and a national security issue as lack of it can cause death, disease, and international tension. Furthermore, efficient water filtration reduces the demand for energy, another national issue. The best current solution to clean water lies in reverse osmosis (RO) membranes that remove salts from water with applied pressure, but widely used polymeric membrane technology is energy intensive and produces water depleted in useful electrolytes. Furthermore incremental improvements, based on engineering solutions rather than new materials, have yielded only modest gains in performance over the last 25 years. We have pursued a creative and innovative new approach to membrane design and development for cheap desalination membranes by approaching the problem at the molecular level of pore design. Our inspiration comes from natural biological channels, which permit faster water transport than current reverse osmosis membranes and selectively pass healthy ions. Aiming for an order-of-magnitude improvement over mature polymer technology carries significant inherent risks. The success of our fundamental research effort lies in our exploiting, extending, and integrating recent advances by our team in theory, modeling, nano-fabrication and platform development. A combined theoretical and experimental platform has been developed to understand the interplay between water flux and ion rejection in precisely-defined nano-channels. Our innovative functionalization of solid state nanoporous membranes with organic protein-mimetic polymers achieves 3-fold improvement in water flux over commercial RO membranes and has yielded a pending patent and industrial interest. Our success has generated useful contributions to energy storage, nanoscience, and membrane technology research and development important for national health and prosperity.

  20. A clinoptilolite-PDMS mixed-matrix membrane for high temperature water softening.

    PubMed

    Yazdanbakhsh, Farzad; Alizadehgiashi, Moien; Sawada, James A; Kuznicki, Steven M

    2016-01-01

    A mixed-matrix membrane composed of polydimethylsiloxane (PDMS) as the continuous phase and clinoptilolite, a naturally occurring zeolite, as the active phase has been used to decrease the conductivity of water by more than 80% across the membrane. Testing was carried out using a cross-flow configuration at temperatures as high as 160 °C using a constant transmembrane pressure of 8 bar. The simple fabrication method for the membrane, the durability of the system under the test conditions, and a suitable flux rate make such membranes promising candidates for industrial wastewater treatment.

  1. Structure changes and water filtration properties of electrospun polyamide nanofibre membranes.

    PubMed

    Daels, N; Harinck, L; Goethals, A; De Clerck, K; Van Hulle, S W H

    2016-01-01

    Nanofibre membranes are studied extensively in water treatment. Inappropriate storage, however, could alter their performance, e.g. regarding water filtration. This shows the need for investigating this effect in more detail so as to offer a solution for long-term behaviour and stability. In this study, polyamide nanofibre membranes were treated under different conditions, simulating the diverse storage conditions and to simulate their use in water filtration systems. Under all these different settings, nanofibre properties (scanning electron microscope pictures, dimensional changes, tensile strength) and water filtration performance (clean water permeability (CWP), bacterial removal) were investigated. The results demonstrate that, as soon as the dimensional change of a membrane is >2%, the CWP, tensile strength and bacterial removal significantly decrease. These dimensional changes occurred when the membrane became dry after it had been in contact with water. As such, it is important to keep the membrane either in dry or in wet conditions to store its unique properties. When heat-treated, the membrane had a higher tensile strength and kept its morphology and characteristics better during storage.

  2. In situ polymerized superhydrophobic and superoleophilic nanofibrous membranes for gravity driven oil-water separation.

    PubMed

    Tang, Xiaomin; Si, Yang; Ge, Jianlong; Ding, Bin; Liu, Lifang; Zheng, Gang; Luo, Wenjing; Yu, Jianyong

    2013-12-07

    Creating an efficient, cost-effective method that can provide simple, practical and high-throughput separation of oil-water mixtures has proved extremely challenging. This work responds to these challenges by designing, fabricating and evaluating a novel fluorinated polybenzoxazine (F-PBZ) modified nanofibrous membrane optimized to achieve gravity driven oil-water separation. The membrane design is then realized by a facile combination of electrospun poly(m-phenylene isophthalamide) (PMIA) nanofibers and an in situ polymerized F-PBZ functional layer incorporating SiO2 nanoparticles (SiO2 NPs). By employing the F-PBZ/SiO2 NP modification, the pristine hydrophilic PMIA nanofibrous membranes are endowed with promising superhydrophobicity with a water contact angle of 161° and superoleophilicity with an oil contact angle of 0°. This new membrane shows high thermal stability (350 °C) and good repellency to hot water (80 °C), and achieves an excellent mechanical strength of 40.8 MPa. Furthermore, the as-prepared membranes exhibited fast and efficient separation of oil-water mixtures by a solely gravity driven process, which makes them good candidates for industrial oil-polluted water treatments and oil spill cleanup, and also provided new insights into the design and development of functional nanofibrous membranes through F-PBZ modification.

  3. Incorporation of Graphene-Related Carbon Nanosheets in Membrane Fabrication for Water Treatment: A Review

    PubMed Central

    Lawler, Jenny

    2016-01-01

    The minimization of the trade-off between the flux and the selectivity of membranes is a key area that researchers are continually working to optimise, particularly in the area of fabrication of novel membranes. Flux versus selectivity issues apply in many industrial applications of membranes, for example the unwanted diffusion of methanol in fuel cells, retention of valuable proteins in downstream processing of biopharmaceuticals, rejection of organic matter and micro-organisms in water treatment, or salt permeation in desalination. The incorporation of nanosheets within membrane structures can potentially lead to enhancements in such properties as the antifouling ability, hydrophilicy and permeability of membranes, with concomitant improvements in the flux/selectivity balance. Graphene nanosheets and derivatives such as graphene oxide and reduced graphene oxide have been investigated for this purpose, for example inclusion of nanosheets within the active layer of Reverse Osmosis or Nanofiltration membranes or the blending of nanosheets as fillers within Ultrafiltration membranes. This review summarizes the incorporation of graphene derivatives into polymeric membranes for water treatment with a focus on a number of industrial applications, including desalination and pharmaceutical removal, where enhancement of productivity and reduction in fouling characteristics have been afforded by appropriate incorporation of graphene derived nanosheets during membrane fabrication. PMID:27999364

  4. Novel carboxymethyl cellulose based nanocomposite membrane: Synthesis, characterization and application in water treatment.

    PubMed

    Saber-Samandari, Samaneh; Saber-Samandari, Saeed; Heydaripour, Samira; Abdouss, Majid

    2016-01-15

    Significant efforts have been made to develop composite membranes with high adsorption efficiencies for water treatment. In this study, a carboxymethyl cellulose-graft-poly(acrylic acid) membrane was synthesized in the presence of silica gel, which was used as an inorganic support. Then, different amounts of bentonite were introduced to the carboxymethyl cellulose (CMC) grafted networks as a multifunctional crosslinker, and nanocomposite membranes were prepared. The nanocomposite membranes were characterized using Fourier transform infrared spectroscopy, and scanning electron microscopy, which revealed their compositions and surface morphologies. The novel synthesized nanocomposite membranes were utilized as adsorbents for the removal of crystal violet (CV) and cadmium (Cd (II)) ions, which were selected as representatives of a dye and a heavy metal, respectively. We explored the effects of various parameters, such as time, pH, temperature, initial concentration of adsorbate solution and amount of adsorbent, on membrane adsorption capacity. Furthermore, the kinetic, adsorption isotherm models and thermodynamic were employed for the description of adsorption processes. The maximum adsorption capacities of membranes for CV and Cd (II) ions were found to be 546 and 781 mg g(-1), respectively. The adsorption of adsorbate ions by all types of nanocomposite membranes followed pseudo-second-order kinetic model and was best fit with the Freundlich adsorption isotherm. The results indicated that the synthesized nanocomposite membrane is an efficient adsorbent for the removal of cationic dye and metal contaminants from aqueous solution during water treatment.

  5. Incorporation of Graphene-Related Carbon Nanosheets in Membrane Fabrication for Water Treatment: A Review.

    PubMed

    Lawler, Jenny

    2016-12-19

    The minimization of the trade-off between the flux and the selectivity of membranes is a key area that researchers are continually working to optimise, particularly in the area of fabrication of novel membranes. Flux versus selectivity issues apply in many industrial applications of membranes, for example the unwanted diffusion of methanol in fuel cells, retention of valuable proteins in downstream processing of biopharmaceuticals, rejection of organic matter and micro-organisms in water treatment, or salt permeation in desalination. The incorporation of nanosheets within membrane structures can potentially lead to enhancements in such properties as the antifouling ability, hydrophilicy and permeability of membranes, with concomitant improvements in the flux/selectivity balance. Graphene nanosheets and derivatives such as graphene oxide and reduced graphene oxide have been investigated for this purpose, for example inclusion of nanosheets within the active layer of Reverse Osmosis or Nanofiltration membranes or the blending of nanosheets as fillers within Ultrafiltration membranes. This review summarizes the incorporation of graphene derivatives into polymeric membranes for water treatment with a focus on a number of industrial applications, including desalination and pharmaceutical removal, where enhancement of productivity and reduction in fouling characteristics have been afforded by appropriate incorporation of graphene derived nanosheets during membrane fabrication.

  6. Chitosan and alginate biopolymer membranes for remediation of contaminated water with herbicides.

    PubMed

    Agostini de Moraes, Mariana; Cocenza, Daniela Sgarbi; da Cruz Vasconcellos, Fernando; Fraceto, Leonardo Fernandes; Beppu, Marisa Masumi

    2013-12-15

    This study investigated the adsorption behavior of the herbicides diquat, difenzoquat and clomazone on biopolymer membranes prepared with alginate and chitosan (pristine and multi-layer model) for contaminated water remediation applications. Herbicides, at concentrations ranging from 5 μM to 200 μM, were adsorbed in either pure alginate, pure chitosan or a bilayer membrane composed of chitosan/alginate. No adsorption of clomazone was observed on any of the membranes, probably due to lack of electrostatic interactions between the herbicide and the membranes. Diquat and difenzoquat were only adsorbed on the alginate and chitosan/alginate membranes, indicating that this adsorption takes place in the alginate layer. At a concentration of 50 μM, diquat adsorption reaches ca. 95% after 120 min on both the alginate and chitosan/alginate membranes. The adsorption of difenzoquat, at the same concentration, reaches ca. 62% after 120 min on pure alginate membranes and ca. 12% on chitosan/alginate bilayer membranes. The adsorption isotherms for diquat and difenzoquat were further evaluated using the isotherm models proposed by Langmuir and by Freundlich, where the latter represented the best-fit model. Results indicate that adsorption occurs via coulombic interactions between the herbicides and alginate and is strongly related to the electrostatic charge, partition coefficients and dissociation constants of the herbicides. Biopolymer based membranes present novel systems for the removal of herbicides from contaminated water sources and hold great promise in the field of environmental science and engineering.

  7. Hydrogen production by high temperature water splitting using electron conducting membranes

    DOEpatents

    Balachandran, Uthamalingam; Wang, Shuangyan; Dorris, Stephen E.; Lee, Tae H.

    2006-08-08

    A device and method for separating water into hydrogen and oxygen is disclosed. A first substantially gas impervious solid electron-conducting membrane for selectively passing protons or hydrogen is provided and spaced from a second substantially gas impervious solid electron-conducting membrane for selectively passing oxygen. When steam is passed between the two membranes at dissociation temperatures the hydrogen from the dissociation of steam selectively and continuously passes through the first membrane and oxygen selectively and continuously passes through the second membrane, thereby continuously driving the dissociation of steam producing hydrogen and oxygen. The oxygen is thereafter reacted with methane to produce syngas which optimally may be reacted in a water gas shift reaction to produce CO2 and H2.

  8. 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.

  9. Scanning force microscopy of synthetic membranes in air and under water: surfaces, cross sections, and fouling

    NASA Astrophysics Data System (ADS)

    Dietz, Peter; Herrmann, Karl-Heinz; Inacker, Otto; Lehmann, Hans-Dieter; Hansma, Paul K.

    1992-05-01

    Atomic force microscopy was used to image surfaces and cross sections of different types of microporous membranes used for ultrafiltration and dialysis. Characteristic surface structures with funnel-shaped pores could be detected with resolution better than 10 nm. Ultrafiltration membranes with molecular weight cutoff values between 5,000 and 100,000 show wide variations in homogeneity, roughness, size and density of pores, but with a basic network-like fine structure. Cross sections allow one to compare inner structure and surface. An evident change of the surface of one membrane was observed after using the membrane over a long time for clearfiltration of juice. Cellulosic dialysis membranes with different biocompatibility were compared in air and under water. Structural differences could be observed between modified and unmodified type. Under water the structures are considerably changed due to swelling processes.

  10. [Track membranes in the filtration technique of determination of the quality of water from bacteriological values].

    PubMed

    Bogatyreva, I A

    2007-01-01

    The paper describes a new class of microfiltration track membranes (TMs) proposed for laboratories to carry out a sanitary water bacteriological test. TMs have a strictly reference pore structure, a low sorption capacity do not contain the components that able to migrate into the filtrate, they are noted for a screening mechanism of holding microparticles onto the surface. The TMs made in Russia, the reticular membranes "Vladipore", and the foreign Millipore membranes certified by the international standards were comprehensively assessed. TMs are superior to the membranes manufactured in Russia at the moment in a number of basic properties that are most essential for the study of water quality and to foreign certified membranes in physical parameters, the specific features of growth of coliform bacteria, the rate of performance of an oxidase test, and the efficiency of retention of various microorganisms.

  11. Membrane permeability and the loss of germination factor from Neurospora crassa at low water activities

    NASA Technical Reports Server (NTRS)

    Charlang, G.; Horowitz, N. H.

    1974-01-01

    Neurospora crassa conidia incubating in buffer at low water activities release a germination-essential component as well as 260-nm absorbing and ninhydrin-positive materials, regardless of whether an electrolyte or nonelectrolyte is used to reduce water activity. Chloroform and antibiotics known to increase cell-membrane permeability have a similar effect. This suggests that membrane damage occurs in media of low water activity and that an increase in permeability is responsible for the release of cellular components. The damage caused in media of low water activity is nonlethal in most cases, and the conidia recover when transferred to nutrient medium.

  12. Pervaporation of water/ethanol mixtures by an aromatic polyetherimide membrane

    SciTech Connect

    Huang, R.Y.M.; Xianshe Feng )

    1992-10-01

    The pervaporation of water/ethanol mixtures through an aromatic polyetherimide membrane was attempted. The membrane was laboratory prepared using the solution casting technique. The sorption characteristics in relation to pervaporation were also studied. It was found that the preferential sorption was altered when the liquid composition was changed, whereas the water component permeated through the membrane preferentially over the whole range of feed mixture compositions. The experimental results were analyzed in terms of sorption ratio and permeation ratio to characterize nonideality of sorption and pervaporation. The effects of some operating parameters, including temperature, feed concentration, and permeate pressure, on the pervaporation performance were also investigated.

  13. Pervaporation separation of ethanol-water mixtures using polyethylenimine composite membranes

    DOEpatents

    Neidlinger, H.H.; Schissel, P.O.; Orth, R.A.

    1987-04-21

    Synthetic, organic, polymeric membranes were prepared from polyethylenimine for use with pervaporation apparatus in the separation of ethanol-water mixtures. The polymeric material was prepared in dilute aqueous solution and coated onto a polysulfone support film, from which excess polymeric material was subsequently removed. Cross-links were then generated by limited exposure to toluene-2,4-diisocyanate solution, after which the prepared membrane was heat-cured. The resulting membrane structures showed high selectivity in permeating ethanol or water over a wide range of feed concentrations.

  14. Pervaporation separation of ethanol-water mixtures using polyacrylic acid composite membranes

    DOEpatents

    Neidlinger, H.H.

    1985-05-07

    Synthetic, organic, polymeric membranes were prepared from polyacrylic acid salts for use with pervaporation apparatus in the separation of ehthanol-water mixtures. The polymeric material was prepared in dilute aqueous solution and coated onto a polysulfone support film, from which excess polymeric material was subsequently removed. Cross-links were then generated by limited exposure to toluene-2,4-diisocyanata solution, after which the prepared membrane was heat-cured. The resulting membrane structure showed selectivity in permeating water over a wide range of feed concentrations. 4 tabs.

  15. Pervaporation separation of ethanol-water mixtures using polyethylenimine composite membranes

    DOEpatents

    Neidlinger, H.H.; Schissel, P.O.; Orth, R.A.

    1985-06-19

    Synthetic, organic, polymeric membranes were prepared from polyethylenimine for use with pervaporation apparatus in the separation of ethanol-water mixtures. The polymeric material was prepared in dilute aqueous solution and coated onto a polysulfone support film, from which excess polymeric material was subsequently removed. Cross-links were then generated by limited exposure to toluene-2,4-diisocyanate solution, after which the prepared membrane was heat-cured. The resulting membrane structures showed high selectivity in permeating ethanol or water over a wide range of feed concentrations. 2 tabs.

  16. Pervaporation separation of ethanol-water mixtures using polyethylenimine composite membranes

    DOEpatents

    Neidlinger, Hermann H.; Schissel, Paul O.; Orth, Richard A.

    1987-01-01

    Synthetic, organic, polymeric membranes were prepared from polyethylenimine for use with pervaporation apparatus in the separation of ethanol-water mixtures. The polymeric material was prepared in dilute aqueous solution and coated onto a polysulfone support film, from which excess polymeric material was subsequently removed. Cross-links were then generated by limited exposure to toluene-2,4-diisocyanate solution, after which the prepared membrane was heat-cured. The resulting membrane structures showed high selectivity in permeating ethanol or water over a wide range of feed concentrations.

  17. Methods for attaching polymerizable ceragenins to water treatment membranes using silane linkages

    DOEpatents

    Hibbs, Michael; Altman, Susan J.; Jones, Howland D. T.; Savage, Paul B.

    2013-09-10

    This invention relates to methods for chemically grafting and attaching ceragenin molecules to polymer substrates; methods for synthesizing ceragenin-containing copolymers; methods for making ceragenin-modified water treatment membranes and spacers; and methods of treating contaminated water using ceragenin-modified treatment membranes and spacers. Ceragenins are synthetically produced antimicrobial peptide mimics that display broad-spectrum bactericidal activity. Alkene-functionalized ceragenins (e.g., acrylamide-functionalized ceragenins) can be attached to polyamide reverse osmosis membranes using amine-linking, amide-linking, UV-grafting, or silane-coating methods. In addition, silane-functionalized ceragenins can be directly attached to polymer surfaces that have free hydroxyls.

  18. Methods for attaching polymerizable ceragenins to water treatment membranes using amine and amide linkages

    DOEpatents

    Hibbs, Michael; Altman, Susan J.; Jones, Howland D.T.; Savage, Paul B.

    2013-10-15

    This invention relates to methods for chemically grafting and attaching ceragenin molecules to polymer substrates; methods for synthesizing ceragenin-containing copolymers; methods for making ceragenin-modified water treatment membranes and spacers; and methods of treating contaminated water using ceragenin-modified treatment membranes and spacers. Ceragenins are synthetically produced antimicrobial peptide mimics that display broad-spectrum bactericidal activity. Alkene-functionalized ceragenins (e.g., acrylamide-functionalized ceragenins) can be attached to polyamide reverse osmosis membranes using amine-linking, amide-linking, UV-grafting, or silane-coating methods. In addition, silane-functionalized ceragenins can be directly attached to polymer surfaces that have free hydroxyls.

  19. Measurement of permeation of membranes by ethanol and water with integrated optics and Raman spectroscopy

    SciTech Connect

    Scherer, J.R.; Bailey, G.F.; Malladi, D.P.

    1983-03-25

    A new method for measuring the permeability of synthetic membranes to water and ethanol has been developed. The technique involves using the membrane as a laser waveguide and making Raman scattering measurements from the guided laser beam. The measurements show that alcohol can be detected at low levels within damp cellulose acetate membranes. The results suggest that further exploration using waveguide and Raman measurements might lead to a better understanding of the mechanisms which affect the relative permeability of alcohol and water. 6 references, 4 figures, 1 table.

  20. Study of polydimethylsiloxane/aromatic polyamide laminated membranes for separation of acetic acid/water mixtures by pervaporation process

    SciTech Connect

    Deng, S.; Sourirajan, S.; Matsuura, T. )

    1994-06-01

    Separation of acetic acid/water mixtures by pervaporation was attempted over a range of compositions using polydimethylsiloxane (PDMS), aromatic polyamide (PA), and laminated polydimethylsiloxane-aromatic polyamide membranes. PDMS membranes are hydrophobic and acetic acid selective, whereas PA membranes are hydrophilic and water selective. When PDMS and PA membranes were laminated, with PDMS on the top side and in contact with the feed, water selectivity of the bottom PA membrane was intensified. On the other hand, when the PA membrane was on the top side and in contact with the feed, the selectivity was lowered. 10 refs., 4 figs.

  1. Influence of Brij58 on the Characteristic and Performance of PES Membrane for Water Treatment Process

    NASA Astrophysics Data System (ADS)

    Mukramah; Syawaliah; Mulyati, S.; Arahman, N.

    2017-03-01

    This study proposes a modification of polyether sulfone (PES) membrane by blending the polymer with a hydrophilic additive of Brij-58. Flat-sheet PES membrane was prepared through a non-solvent induced phase separation (NIPS) method using dimethylformamide (DMF) as a solvent. PES membrane was modified by adding Brij-58 into dope solution at a different concentration, i.e 1, 3, 5, 7, and 10 wt %. The fabricated membranes were characterized by means of Scanning Electron Microscopy (SEM) and Fourier Transform Infra-Red (FTIR) spectroscopy. Filtration performance of membrane was analyzed by using a dead-end module. It is found that the addition of a small amount of Brij into polymer solution brought about the increase of water flux. FT-IR investigation showed that the additive exist on the surface of a blended membrane.

  2. Metalized Nanocellulose Composites as a Feasible Material for Membrane Supports: Design and Applications for Water Treatment.

    PubMed

    Cruz-Tato, Perla; Ortiz-Quiles, Edwin O; Vega-Figueroa, Karlene; Santiago-Martoral, Liz; Flynn, Michael; Díaz-Vázquez, Liz M; Nicolau, Eduardo

    2017-04-04

    Herein, we study the feasibility of using nanocellulose (NC)-based composites with silver and platinum nanoparticles as additive materials to fabricate the support layer of thin film composite (TFC) membranes for water purification applications. In brief, the NC surface was chemically modified and then was decorated with silver and platinum nanoparticles, respectively, by chemical reduction. These metalized nanocellulose composites (MNC) were characterized by several techniques including: FTIR, XPS, TGA, XRD, and XANES to probe their integrity. Thereafter, we fabricated the MNC-TFC membranes and the support layer was modified to improve the membrane properties. The membranes were thoroughly characterized, and the performance was evaluated in forward osmosis (FO) mode with various feed solutions: nanopure water, urea, and wastewater samples. The fabricated membranes exhibited finger-like pore morphologies and varying pore sizes. Interestingly, higher water fluxes and solute rejection was obtained with the MNC-TFC membranes with wastewater samples. The overall approach of this work provides an effort to fabricated membranes with high water flux and enhanced selectivity.

  3. Pyrosequencing demonstrated complex microbial communities in a membrane filtration system for a drinking water treatment plant.

    PubMed

    Kwon, Soondong; Moon, Eunjeong; Kim, Taek-Seung; Hong, Seungkwan; Park, Hee-Deung

    2011-01-01

    Microbial community composition in a pilot-scale microfiltration plant for drinking water treatment was investigated using high-throughput pyrosequencing technology. Sequences of 16S rRNA gene fragments were recovered from raw water, membrane tank particulate matter, and membrane biofilm, and used for taxonomic assignments, estimations of diversity, and the identification of potential pathogens. Greater bacterial diversity was observed in each sample (1,133-1,731 operational taxonomic units) than studies using conventional methods, primarily due to the large number (8,164-22,275) of sequences available for analysis and the identification of rare species. Betaproteobacteria predominated in the raw water (61.1%), while Alphaproteobacteria were predominant in the membrane tank particulate matter (42.4%) and membrane biofilm (32.8%). The bacterial community structure clearly differed for each sample at both the genus and species levels, suggesting that different environmental and growth conditions were generated during membrane filtration. Moreover, signatures of potential pathogens including Legionella, Pseudomonas, Aeromonas, and Chromobacterium were identified, and the proportions of Legionella and Chromobacterium were elevated in the membrane tank particulate matter, suggesting a potential threat to drinking water treated by membrane filtration.

  4. Virus disinfection in water by biogenic silver immobilized in polyvinylidene fluoride membranes.

    PubMed

    De Gusseme, Bart; Hennebel, Tom; Christiaens, Eline; Saveyn, Hans; Verbeken, Kim; Fitts, Jeffrey P; Boon, Nico; Verstraete, Willy

    2011-02-01

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag(0)) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag(0) particles, preventing aggregation during encapsulation. In this study, bio-Ag(0) was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag(0) and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag(+) from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag(0)(powder) m(-2) in a submerged plate membrane reactor operated at a flux of 3.1 L m(-2) h(-1). Upon startup, the silver concentration in the effluent initially increased to 271 μg L(-1) but after filtration of 31 L m(-2), the concentration approached the drinking water limit ( = 100 μg L(-1)). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m(-2) h(-1), showing the potential of this membrane technology for water disinfection on small scale.

  5. Removal of endotoxin from water by microfiltration through a microporous polyethylene hollow-fiber membrane

    SciTech Connect

    Sawada, Y.; Fujii, R.; Igami, I.; Kawai, A.; Kamiki, T.; Niwa, M.

    1986-04-01

    The microporous polyethylene hollow-fiber membrane has a unique microfibrile structure throughout its depth and has been found to possess the functions of filtration and adsorption of endotoxin in water. The membrane has a maximum pore diameter of approximately 0.04 micron, a diameter which is within the range of microfiltration. Approximately 10 and 20% of the endotoxin in tap water and subterranean water, respectively, was smaller than 0.025 micron. Endotoxin in these water sources was efficiently removed by the microporous polyethylene hollow-fiber membrane. Escherichia coli O113 culture broth contained 26.4% of endotoxin smaller than 0.025 micron which was also removed. Endotoxin was leaked into the filtrate only when endotoxin samples were successively passed through the membrane. These results indicate that endotoxin smaller than the pore size of the membrane was adsorbed and then leaked into the filtrate because of a reduction in binding sites. Dissociation of /sup 3/H-labeled endotoxin from the membrane was performed, resulting in the removal of endotoxin associated with the membrane by alcoholic alkali at 78% efficiency.

  6. Ion transport through dimethyl sulfoxide (DMSO) induced transient water pores in cell membranes.

    PubMed

    He, Fei; Liu, Weirong; Zheng, Shengchao; Zhou, Li; Ye, Benlan; Qi, Zhi

    2012-01-01

    It is well known that dimethyl sulphoxide (DMSO) increases membrane permeability, which makes it widely used as a vehicle to facilitate drug delivery across biological membranes. However, the mechanism of how DMSO increases membrane permeability has not been well understood. Recently, molecular dynamics simulations have demonstrated that DMSO can induce water pores in biological membranes, but no direct experimental evidence is so far available to prove the simulation result. Using FluxOR Tl⁺ influx assay and intracellular Ca²⁺ imaging technique, we studied the effect of DMSO on Tl⁺ and Ca²⁺ permeation across cell membranes. Upon application of DMSO on CHO-K1 cell line, Tl⁺ influx was transiently increased in a dose-dependent manner. The increase in Tl⁺ permeability induced by DMSO was not changed in the presence of blockers for K⁺ channel and Na⁺-K⁺ ATPase, suggesting that Tl⁺ permeates through transient water pores induced by DMSO to enter into the cell. In addition, Ca²⁺ permeability was significantly increased upon application of DMSO, indicating that the transient water pores induced by DMSO were non-selective pores. Furthermore, similar results could be obtained from RAW264.7 macrophage cell line. Therefore, this study provided experimental evidence to support the prediction that DMSO can induce transient water pores in cell membranes, which in turn facilitates the transport of active substances across membranes.

  7. Permeability of Rubbery and Glassy Membranes of Ionic Liquid Filled Polymersome Nanoreactors in Water.

    PubMed

    So, Soonyong; Yao, Letitia J; Lodge, Timothy P

    2015-12-03

    Nanoemulsion-like polymer vesicles (polymersomes) having ionic liquid interiors dispersed in water are attractive for nanoreactor applications. In a previous study, we demonstrated that small molecules could pass through rubbery polybutadiene membranes on a time scale of seconds, which is practical for chemical transformations. It is of interest to determine how sensitive the rate of transport is to temperature, particularly for membranes in the vicinity of the glass transition (Tg). In this work, the molecular exchange rate of 1-butylimidazole through glassy polystyrene (PS) bilayer membranes is investigated via pulsed field gradient nuclear magnetic resonance (PFG-NMR) over the temperature range from 25 to 70 °C. The vesicles were prepared by the cosolvent method in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([EMIM][TFSI]), and four different polystyrene-b-poly(ethylene oxide) (PS-PEO) diblock polymers with varying PS molecular weights were examined. The vesicles were transferred from the ionic liquid to water at room temperature to form nanoemulsion solutions of polymer vesicles in water. The exchange rate of 1-butylimidazole added to the aqueous solutions was observed under equilibrium conditions at each temperature. The exchange rate decreased as the membrane thickness increased, and the exchange rate through the glassy membranes was three to four times slower than through the rubbery polybutadiene membranes under the same experimental conditions. These results demonstrate that the permeability through nanosized membranes depends on both the dimension and chemistry of membrane-forming blocks. Furthermore, the exchange rate was investigated as a function of temperature in the vicinity of the Tg of PS-PEO membranes. The exchange rate, however, is not a strong function of the temperature in the vicinity of the membrane Tg, due to a combination of the nanoscopic dimension of the membrane, and some degree of solvent

  8. Structure/property relationships in polymer membranes for water purification and energy applications

    NASA Astrophysics Data System (ADS)

    Geise, Geoffrey

    Providing sustainable supplies of purified water and energy is a critical global challenge for the future, and polymer membranes will play a key role in addressing these clear and pressing global needs for water and energy. Polymer membrane-based processes dominate the desalination market, and polymer membranes are crucial components in several rapidly developing power generation and storage applications that rely on membranes to control rates of water and/or ion transport. Much remains unknown about the influence of polymer structure on intrinsic water and ion transport properties, and these relationships must be developed to design next generation polymer membrane materials. For desalination applications, polymers with simultaneously high water permeability and low salt permeability are desirable in order to prepare selective membranes that can efficiently desalinate water, and a tradeoff relationship between water/salt selectivity and water permeability suggests that attempts to prepare such materials should rely on approaches that do more than simply vary polymer free volume. One strategy is to functionalize hydrocarbon polymers with fixed charge groups that can ionize upon exposure to water, and the presence of charged groups in the polymer influences transport properties. Additionally, in many emerging energy applications, charged polymers are exposed to ions that are very different from sodium and chloride. Specific ion effects have been observed in charged polymers, and these effects must be understood to prepare charged polymers that will enable emerging energy technologies. This presentation discusses research aimed at further understanding fundamental structure/property relationships that govern water and ion transport in charged polymer films considered for desalination and electric potential field-driven applications that can help address global needs for clean water and energy.

  9. Pervaporation study for the dehydration of tetrahydrofuran-water mixtures by polymeric and ceramic membranes.

    PubMed

    McGinness, Colleen A; Slater, C Stewart; Savelski, Mariano J

    2008-12-01

    Pervaporation technology can effectively separate a tetrahydrofuran (THF) solvent-water waste stream at an azeotropic concentration. The performance of a Sulzer 2210 polyvinyl alcohol (PVA) membrane and a Pervatech BV silica membrane were studied, as the operating variables feed temperature and permeate pressure, were varied. The silica membrane was found to exhibit a flux of almost double that of the PVA membrane, but both membranes had comparable separation ability in purifying the solvent-water mixture. At benchmark feed conditions of 96 wt% THF and 4 wt% water, 50 degrees C and 10 torr permeate pressure, the silica membrane flux was 0.276 kg/m(2)hr and selectivity was 365. For both membranes, flux was found to increase at an exponential rate as the feed temperature increased from 20 to 60 degrees C. The flux through the silica membrane increases at a 6% faster rate than the PVA membrane. Flux decreased as permeate pressure was increased from 5 to 25 torr for both membranes. The amount of water in the permeate decreased exponentially as the permeate pressure was increased, but increased linearly with increasing temperature. Optimum conditions for flux and selectivity are at low permeate pressure and high feed temperature. When a small amount of salt is added to the feed solution, an increase in flux is observed. Overall models for flux and permeate concentration were created from the experimental data. The models were used to predict scale-up performance in separating an azeotropic feed waste to produce dehydrated THF solvent for reuse and a permeate stream with a dilute THF concentration.

  10. Dependences of water permeation through cyclic octa-peptide nanotubes on channel length and membrane thickness.

    PubMed

    Liu, Jian; Fan, Jianfen; Cen, Min; Song, Xuezeng; Liu, Dongyan; Zhou, Weiqun; Liu, Zhao; Yan, Jianfeng

    2012-08-27

    Effects of the channel length and membrane thickness on the water permeation through the transmembrane cyclic octa-peptide nanotubes (octa-PNTs) have been studied by molecular dynamics (MD) simulations. The water osmotic permeability (p(f)) through the PNTs of k × (WL)(4)/POPE (1-palmitoyl-2-oleoyl-glycerophosphoethanolamine; k = 6, 7, 8, 9, and 10) was found to decay with the channel length (L) along the axis (~L(-2.0)). Energetic analysis showed that a series of water binding sites exist in these transmembrane PNTs, with the barriers of ~3k(B)T, which elucidates the tendency of p(f) well. Water diffusion permeability (p(d)) exhibits a relationship of ~L(-1.8), which results from the novel 1-2-1-2 structure of water chain in such confined nanolumens. In the range of simulation accuracy, the ratio (p(f)/p(d)) of the water osmotic and diffusion permeability is approximately a constant. MD simulations of water permeation through the transmembrane PNTs of 8 × (WL)(4)/octane with the different octane membrane thickness revealed that the water osmotic and diffusion permeability (p(f) and p(d)) are both independent of the octane membrane thickness, confirmed by the weak and nearly same interactions between the channel water and octane membranes with the different thickness. The results may be helpful for revealing the permeation mechanisms of biological water channels and designing artificial nanochannels.

  11. 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

  12. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    NASA Astrophysics Data System (ADS)

    Rønnest, A. K.; Peters, G. H.; Hansen, F. Y.; Taub, H.; Miskowiec, A.

    2016-04-01

    Molecular dynamics simulations have been used to investigate the influence of the valency of counter-ions on the structure of freestanding bilayer membranes of the anionic 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) lipid at 310 K and 1 atm. At this temperature, the membrane is in the fluid phase with a monovalent counter-ion and in the gel phase with a divalent counter-ion. The diffusion constant of water as a function of its depth in the membrane has been determined from mean-square-displacement calculations. Also, calculated incoherent quasielastic neutron scattering functions have been compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic potential within phospholipid membranes imply an enormous electric field of 108-109 V m-1, which is likely to have great significance in controlling the conformation of translocating membrane proteins and in the transfer of ions and molecules across the membrane. We have calculated the membrane potential for DMPG bilayers and found ˜1 V (˜2 ṡ 108 V m-1) when in the fluid phase with a monovalent counter-ion and ˜1.4 V (˜2.8 ṡ 108 V m-1) when in the gel phase with a divalent counter-ion. The number of water molecules for a fully hydrated DMPG membrane has been estimated to be 9.7 molecules per lipid in the gel phase and 17.5 molecules in the fluid phase, considerably smaller than inferred experimentally for 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC

  13. Ultrathin cellulose nanosheet membranes for superfast separation of oil-in-water nanoemulsions

    NASA Astrophysics Data System (ADS)

    Zhou, Ke; Zhang, Qiu Gen; Li, Hong Mei; Guo, Nan Nan; Zhu, Ai Mei; Liu, Qing Lin

    2014-08-01

    Oily wastewater is generated in diverse industrial processes, and its treatment has become crucial due to increasing environmental concerns. Herein, novel ultrathin nanoporous membranes of cellulose nanosheets have been fabricated for separation of oil-in-water nanoemulsions. The fabrication approach is facile and environmentally friendly, in which cellulose nanosheets are prepared by freeze-extraction of a very dilute cellulose solution. The as-prepared membranes have a cellulose nanosheet layer with a cut-off of 10-12 nm and a controllable thickness of 80-220 nm. They allow ultrafast water permeation and exhibit excellent size-selective separation properties. A 112 nm-thick membrane has a water flux of 1620 l m-2 h-1 bar-1 and a ferritin rejection of 92.5%. These membranes have been applied to remove oil from its aqueous nanoemulsions successfully, and they show an ultrafast and effective separation of oil-in-water nanoemulsions. The newly developed ultrathin cellulose membranes have a wide application in oily wastewater treatment, separation and purification of nanomaterials.Oily wastewater is generated in diverse industrial processes, and its treatment has become crucial due to increasing environmental concerns. Herein, novel ultrathin nanoporous membranes of cellulose nanosheets have been fabricated for separation of oil-in-water nanoemulsions. The fabrication approach is facile and environmentally friendly, in which cellulose nanosheets are prepared by freeze-extraction of a very dilute cellulose solution. The as-prepared membranes have a cellulose nanosheet layer with a cut-off of 10-12 nm and a controllable thickness of 80-220 nm. They allow ultrafast water permeation and exhibit excellent size-selective separation properties. A 112 nm-thick membrane has a water flux of 1620 l m-2 h-1 bar-1 and a ferritin rejection of 92.5%. These membranes have been applied to remove oil from its aqueous nanoemulsions successfully, and they show an ultrafast and effective

  14. Influence of swelling on water transport through PVA-based membrane

    NASA Astrophysics Data System (ADS)

    Praptowidodo, Veronica S.

    2005-04-01

    Dehydration of ethanol is studied using various PVA-based membranes. Due to its high solubility in water, PVA membrane has a great extent of swelling in ethanol-water mixture, resulting in a remarkable decline of selectivity. To restrict the extent of swelling, PVA membranes were chemically modified by crosslinking reaction by glutaraldehyde. Crosslinking reaction was conducted by using two concentrations of glutaraldehyde, i.e. 0.025 and 0.100% by weight, and the degree of crosslinking was varied by changing the reaction time. The difference degree of crosslinking was examined by the extent of swelling. Those modified membranes were performed by pervaporation to study the effect of crosslinking on separation process. Crosslinked PVA-membrane with 26.5% swelling degree, produced flux 0.28 kg/m 2 h, and separation factor 104 at the condition of pervaporation at 40 °C and 0.4 mbar downstream pressure, using feed solution 90 wt% of ethanol. The present of charged groups in PVA-N and PVA-It membranes decrease the swelling degree to 15.65 and 14.00%, respectively. At feed concentration of ethanol 96% by pervaporation, PVA membrane with swelling degree 26.5%, produced flux, J=0.279 kg/m 2 h and separation factor, α=107; PVA-N membrane flux, J=0.123 kg/m 2 h and separation factor, α=216; PVA-It membrane flux, J=0.119 kg/m 2 h and separation factor, α=228. The present of charged groups increase selectivity, however it decrease flux. By decreasing down stream pressure from 0.4 to 0.14 mbar at the same pervaporation condition, the membrane selectivity changed to a higher values, PVA membrane flux, J=0.189 kg/m 2 h and separation factor, α=335; PVA-N membranes flux, J=0.089 kg/m 2 h and separation factor α=709; PVA-It membranes flux, J=0.086 kg/m 2 h and separation factor α=837. The presence of charged groups in polymers and the down stream pressure influence potentially to improve membrane selectivity. Substitution of anionic and cationic charged groups to PVA

  15. Removal of aqueous nC60 fullerene from water by low pressure membrane filtration.

    PubMed

    Floris, R; Nijmeijer, K; Cornelissen, E R

    2016-03-15

    The potential environmental and health risks of engineered nanoparticles such as buckminsterfullerene C60 in water require their removal during the production of drinking water. We present a study focusing on (i) the removal mechanism and (ii) the elucidation of the role of the membrane pore size during removal of nC60 fullerene nanoparticle suspensions in dead-end microfiltration and ultrafiltration mimicking separation in real industrial water treatment plants. Membranes were selected with pore sizes ranging from 18 nm to 500 nm to determine the significance of the nC60 to membrane pore size ratio and the adsorption affinity between nC60 and membrane material during filtration. Experiments were carried out with a dead-end bench-scale system operated at constant flux conditions including a hydraulic backwash cleaning procedure. nC60 nanoparticles can be efficiently removed by low pressure membrane technology with smaller and, unexpectedly, also by mostly similar or larger pores than the particle size, although the nC60 filtration behaviour appeared to be different. The nC60 size to membrane pore size ratio and the ratio of the cake-layer deposition resistance to the clean membrane resistance, both play an important role on the nC60 filtration behaviour and on the efficiency of the backwash procedure recovering the initial membrane filtration conditions. These results become specifically significant in the context of drinking water production, for which they provide relevant information for an accurate selection between membrane processes and operational parameters for the removal of nC60 in the drinking water treatment.

  16. Microbial community analysis of fouled reverse osmosis membranes used in water recycling.

    PubMed

    Ayache, C; Manes, C; Pidou, M; Croué, J P; Gernjak, W

    2013-06-15

    Biofouling on RO membranes has major cost implications in water reclamation. In this study membranes and water samples were collected from a RO pilot-plant operated on two sites to study the differences in microbial communities in order to develop a better understanding of the biofouling. For the two sites studied, the examination of the front membrane of the first stage and the tail membrane of the second stage of the RO train using 16S rRNA gene-based molecular technique showed that bacteria were similar on both stages and no significant effect of the membrane location within the RO train on the biofilm development could be discerned. However, the comparison of the identified bacteria from membrane samples between the two sites showed that each site is specific, leading to a different composition of microbial communities. The different nutrient concentrations in the RO feed water due to the different biological pre-treatments are one potential explanation for the observed differences in the microbial communities. Seasonal variations also play a major role in the development of microbial communities as shown by the significant differences observed between the communities measured in the samples in winter and summer on the second site. The results did not show similarity between the species identified on the RO membranes and in the feed water. Hence, the relationship of microbial community between the water generated during the pre-treatment process and RO membranes is not obvious. From this study, results showed that there is an actual need to investigate the development of microbial communities on membrane surface in real conditions in order to suggest tailored solutions for biofouling control and removal.

  17. Local area water removal analysis of a proton exchange membrane fuel cell under gas purge conditions.

    PubMed

    Lee, Chi-Yuan; Lee, Yu-Ming; Lee, Shuo-Jen

    2012-01-01

    In this study, local area water content distribution under various gas purging conditions are experimentally analyzed for the first time. The local high frequency resistance (HFR) is measured using novel micro sensors. The results reveal that the liquid water removal rate in a membrane electrode assembly (MEA) is non-uniform. In the under-the-channel area, the removal of liquid water is governed by both convective and diffusive flux of the through-plane drying. Thus, almost all of the liquid water is removed within 30 s of purging with gas. However, liquid water that is stored in the under-the-rib area is not easy to remove during 1 min of gas purging. Therefore, the re-hydration of the membrane by internal diffusive flux is faster than that in the under-the-channel area. Consequently, local fuel starvation and membrane degradation can degrade the performance of a fuel cell that is started from cold.

  18. Contaminant Permeation in the Ionomer-Membrane Water Processor (IWP) System

    NASA Technical Reports Server (NTRS)

    Kelsey, Laura K.; Finger, Barry W.; Pasadilla, Patrick; Perry, Jay

    2016-01-01

    The Ionomer-membrane Water Processor (IWP) is a patented membrane-distillation based urine brine water recovery system. The unique properties of the IWP membrane pair limit contaminant permeation from the brine to the recovered water and purge gas. A paper study was conducted to predict volatile trace contaminant permeation in the IWP system. Testing of a large-scale IWP Engineering Development Unit (EDU) with urine brine pretreated with the International Space Station (ISS) pretreatment formulation was then conducted to collect air and water samples for quality analysis. Distillate water quality and purge air GC-MS results are presented and compared to predictions, along with implications for the IWP brine processing system.

  19. Swollen-dry-layer model for the pervaporation of ethanol-water solution through hydrophilic membranes

    SciTech Connect

    Ito, A.; Watanabe, K.; Feng, Y.

    1995-09-01

    A swollen-dry-layer model is presented for the pervaporation of ethanol-water solution through hydrophilic polymer membranes: poly(vinyl alcohol) and carboxymethyl cellulose. Independent measurements were conducted of the sorption equilibrium, the hydraulic permeation rates through the swollen membranes, and the permeabilities of ethanol and water vapors. The hydraulic permeabilities were estimated from the mutual diffusion coefficients of solution in the swollen membrane. Sorption behavior and hydraulic permeabilities showed a dependence on feed concentration. Vapor permeabilities of water and ethanol through dry membranes differ by a factor of about 20. Comparisons between the experimental data from the pervaporation run and the results calculated from the model were made. The model offers a quantitative explanation for the dependency of selectivity and flux on feed concentration. The model explained that the flux dependency caused by a change in the swollen-dry-layer ratio, and that the selectivity is governed by vapor permeabilities through the dry layer.

  20. Membrane-Based Gas Traps for Ammonia, Freon-21, and Water Systems to Simplify Ground Processing

    NASA Technical Reports Server (NTRS)

    Ritchie, Stephen M. C.

    2003-01-01

    Gas traps are critical for the smooth operation of coolant loops because gas bubbles can cause loss of centrifugal pump prime, interference with sensor readings, inhibition of heat transfer, and blockage of passages to remote systems. Coolant loops are ubiquitous in space flight hardware, and thus there is a great need for this technology. Conventional gas traps will not function in micro-gravity due to the absence of buoyancy forces. Therefore, clever designs that make use of adhesion and momentum are required for adequate separation, preferable in a single pass. The gas traps currently used in water coolant loops on the International Space Station are composed of membrane tube sets in a shell. Each tube set is composed of a hydrophilic membrane (used for water transport and capture of bubbles) and a hydrophobic membrane (used for venting of air bubbles). For the hydrophilic membrane, there are two critical pressures, the pressure drop and the bubble pressure. The pressure drop is the decrease in system pressure across the gas trap. The bubble pressure is the pressure required for air bubbles to pass across the water filled membrane. A significant difference between these pressures is needed to ensure complete capture of air bubbles in a single pass. Bubbles trapped by the device adsorb on the hydrophobic membrane in the interior of the hydrophilic membrane tube. After adsorption, the air is vented due to a pressure drop of approximately 1 atmosphere across the membrane. For water systems, the air is vented to the ambient (cabin). Because water vapor can also transport across the hydrophobic membrane, it is critical that a minimum surface area is used to avoid excessive water loss (would like to have a closed loop for the coolant). The currently used gas traps only provide a difference in pressure drop and bubble pressure of 3-4 psid. This makes the gas traps susceptible to failure at high bubble loading and if gas venting is impaired. One mechanism for the latter

  1. Analysis of micromixers and biocidal coatings on water-treatment membranes to minimize biofouling.

    SciTech Connect

    Webb, Stephen W.; James, Darryl L.; Hibbs, Michael R.; Jones, Howland D. T.; Hart, William Eugene; Khalsa, Siri Sahib; Altman, Susan Jeanne; Clem, Paul Gilbert; Elimelech, Menachem; Cornelius, Christopher James; Sanchez, Andres L.; Noek, Rachael M.; Ho, Clifford Kuofei; Kang, Seokatae; Sun, Amy Cha-Tien; Adout, Atar; McGrath, Lucas K.; Cappelle, Malynda A.; Cook, Adam W.

    2009-12-01

    Biofouling, the unwanted growth of biofilms on a surface, of water-treatment membranes negatively impacts in desalination and water treatment. With biofouling there is a decrease in permeate production, degradation of permeate water quality, and an increase in energy expenditure due to increased cross-flow pressure needed. To date, a universal successful and cost-effect method for controlling biofouling has not been implemented. The overall goal of the work described in this report was to use high-performance computing to direct polymer, material, and biological research to create the next generation of water-treatment membranes. Both physical (micromixers - UV-curable epoxy traces printed on the surface of a water-treatment membrane that promote chaotic mixing) and chemical (quaternary ammonium groups) modifications of the membranes for the purpose of increasing resistance to biofouling were evaluated. Creation of low-cost, efficient water-treatment membranes helps assure the availability of fresh water for human use, a growing need in both the U. S. and the world.

  2. Novel Perfluorinated Polymer-Based Pervaporation Membranes for Separation of Solvent/Water Mixtures.

    PubMed

    Smuleac, V; Wu, J; Nemser, S; Majumdar, S; Bhattacharyya, D

    2010-04-15

    Traditionally, the pervaporation of water-solvent mixtures where the solvent is the major component is performed using hydrophilic membranes (such as PVA or zeolites). In the present paper a new type of pervaporation membrane (amorphous perfluorinated polymer, hydrophobic) was studied for separation of water-solvent mixtures. This membrane has high free volume and is inert for all solvents, and has a remarkable mechanical, chemical and thermal stability. The water is transported by solution diffusion model and the separation of solvent is primarily based on molecular sieving (size exclusion) principles. The membrane shows a high stability for operation over a broad range of feed concentrations without swelling; the operating temperature does not have a significant effect on membrane separation performance. Separation factors as high as 349 and 500 for water-ethanol and water-IPA mixtures (2-98 % wt water-solvent) and fluxes of 0.15 and 0.05 kg/m(2)h, respectively were obtained at 22 °C. The permeance-based selectivities were also calculated, and the selectivity is approximately constant for a wide range of feed concentrations. The pervaporation of more complex (ternary) mixtures of water-ethanol-ethyl acetate showed that this system could be successfully applied for solute separation based on size exclusion.

  3. Review on the fate of organic micropollutants in wastewater treatment and water reuse with membranes.

    PubMed

    Siegrist, H; Joss, A

    2012-01-01

    A brief review of the fate of micropollutants in membrane-based wastewater treatment due to sorption, stripping, biological degradation/transformation and membrane separation is discussed, to give an overview of these technologies due to the growing importance for water reuse purposes. Compared with conventional activated sludge treatment (CAS) micropollutant removal in membrane bioreactor (MBR) is slightly improved due to complete suspended solids removal and increased sludge age. For discharge to sensitive receiving waters advanced treatment, such as post-ozonation or activated carbon adsorption, is recommended. In water reuse plants nanofiltration (NF) and reverse osmosis (RO) efficiently reject micropollutants due to size exclusions as well as electrostatic and hydrophobic effects reaching potable quality. To remove micropollutants fully, additionally post-ozone or the addition of powdered activated carbon (PAC) have to be applied, which in parallel also reduce NDMA precursors. The concentrate has to be treated if disposed to sensitive receiving waters due to its high micropollutant concentration and ecotoxicity potential. The present review summarizes principles and capabilities for the most important membrane-based applications for wastewater treatment, i.e. porous membranes in MBRs (micro- or ultrafiltration) and dense membrane applications (NF and RO) for water reuse.

  4. Modeling of a water vapor selective membrane unit to increase the energy efficiency of humidity harvesting

    NASA Astrophysics Data System (ADS)

    Bergmair, D.; Metz, S. J.; de Lange, H. C.; van Steenhoven, A. A.

    2012-11-01

    Air humidity is a promising source of clean and safe drinking water. However, in conventional systems a lot of energy is wasted on the production of cold air, rather than the condensation of water vapor. This study examines the possibility of using a hollow fiber membrane module to make this process more energy efficient, by separating the vapor from other gases, prior to the cooling process with the help of selective membranes. The water vapor concentration within a fiber has been modeled using a random walker approach, and the membrane permeability has been implemented as a re-bounce probability for simulation particles interacting with the membrane. Considering the additional work requirement for driving a feed flow through the membrane section and the computed water vapor permeation it could be shown that the energy demand per unit water is lowest for slow flow speeds and favors short and thin fibers. The total energy requirement was estimated to be less than half of the conventional one. Comparison with other CFD simulations and a real life module has shown a good level of agreement, indicating that a membrane section could improve the energy efficiency of humidity harvesting significantly.

  5. Removal of organics from offshore produced waters using nanofiltration membrane technology

    SciTech Connect

    Dyke, C.A.; Bartels, C.R. )

    1990-08-01

    The separation of oil and produced water mixtures from oil and gas producing wells has traditionally been accomplished by gravity settlers (e.g., multi-phase separators, skimmers, and flotation cells). However, current EPA regulations on the organic content of discharged produced water have reached the limits of these separation techniques. The industry is in need of new technologies to treat these waters. One such technology that the authors have found promising is organics/water separation by nanofiltration membranes.

  6. JWST Lifting System

    NASA Technical Reports Server (NTRS)

    Tolleson, William

    2012-01-01

    A document describes designing, building, testing, and certifying a customized crane (Lifting Device LD) with a strong back (cradle) to facilitate the installation of long wall panels and short door panels for the GHe phase of the James Webb Space Telescope (JWST). The LD controls are variable-frequency drive controls designed to be adjustable for very slow and very-short-distance movements throughout the installation. The LD has a lift beam with an electric actuator attached at the end. The actuator attaches to a rectangular strong back (cradle) for lifting the long wall panels and short door panels from a lower angle into the vertical position inside the chamber, and then rotating around the chamber for installation onto the existing ceiling and floor. The LD rotates 360 (in very small increments) in both clockwise and counterclockwise directions. Eight lifting pads are on the top ring with 2-in. (.5-cm) eye holes spaced evenly around the ring to allow for the device to be suspended by three crane hoists from the top of the chamber. The LD is operated by remote controls that allow for a single, slow mode for booming the load in and out, with slow and very slow modes for rotating the load.

  7. Forehead lift - slideshow

    MedlinePlus

    ... Indications URL of this page: //medlineplus.gov/ency/presentations/100020.htm Forehead lift - series—Indications To use the sharing features on this page, please enable JavaScript. Go to slide 1 out of 3 Go to slide 2 ...

  8. Breast lift (mastopexy) - slideshow

    MedlinePlus

    ... Incisions URL of this page: //medlineplus.gov/ency/presentations/100188.htm Breast lift (mastopexy) - series—Incisions To use the sharing features on this page, please enable JavaScript. Go to slide 1 out of 3 Go to slide 2 ...

  9. Lifting as You Climb

    ERIC Educational Resources Information Center

    Sullivan, Debra R.

    2009-01-01

    This article addresses leadership themes and answers leadership questions presented to "Exchange" by the Panel members who attended the "Exchange" Panel of 300 Reception in Dallas, Texas, last November. There is an old proverb that encourages people to lift as they climb: "While you climb a mountain, you must not forget others along the way." With…

  10. Using permeable membranes to produce hydrogen and oxygen from water

    NASA Technical Reports Server (NTRS)

    Sanders, A. P.; Williams, R. J.; Downs, W. R.; Mcbryar, H.

    1975-01-01

    Concept may make it profitable to obtain hydrogen fuel from water. Laboratory tests have demonstrated that method enables decomposition of water several orders of magnitude beyond equilibrium state where only small amounts of free hydrogen are present.

  11. Bi-modal water transport behavior across a simple Nafion membrane

    NASA Astrophysics Data System (ADS)

    Zhang, Ziheng; Promislow, Keith; Martin, Jonathan; Wang, Haijiang; Balcom, Bruce J.

    2011-10-01

    The development of predictive mathematical models for water management in polymer electrolyte membrane fuel cells requires detailed understanding of water distribution and water transport across the Nafion layer. The anisotropic microstructure of Nafion suggests the measurement of water content and mass transport should be along the fuel cell functional direction, i.e. across the membrane. Non-invasive, high resolution, microscopy measurements of this type are very challenging. We report here the calibration of a minimal mathematical model for diffusive water transport in Nafion against data from high-resolution water content maps determined with a new magnetic resonance imaging methodology developed for this purpose. A mock fuel cell was designed to permit well-controlled wetting and drying boundary conditions. With no chemical potential driving force involved, we assume the water transport behavior will be dominated by diffusion. Moreover we show that, in this context, our model is mathematically equivalent to the traditional permeation models based upon saturation dependent pressure gradients via a capillary pressure ansatz. The non-linear equilibrium water distribution across the Nafion membrane measured in this work suggests a bi-modal diffusivity. The model constructed associates distinct transport behaviors to water contents above and below a critical threshold, consistent with a rearrangement of a micro-structural pore network. The experimental observation and the model prediction agree with the primary features of Weber's model of Nafion, which predicts distinct modes of transport for hydration fronts traversing the through-plane direction of the membrane.

  12. Alkali doped poly (2,5-benzimidazole) membrane for alkaline water electrolysis: Characterization and performance

    NASA Astrophysics Data System (ADS)

    Diaz, Liliana A.; Hnát, Jaromír; Heredia, Nayra; Bruno, Mariano M.; Viva, Federico A.; Paidar, Martin; Corti, Horacio R.; Bouzek, Karel; Abuin, Graciela C.

    2016-04-01

    The properties and performance of linear and cross-linked KOH doped ABPBI membranes as electrolyte/separator for zero gap alkaline water electrolysis cells are evaluated and compared with a commercial Zirfon® diaphragm. Stability in alkaline environment, swelling, thermal properties, water sorption, KOH uptake and conductivity of linear (L-ABPBI) and cross-linked (C-ABPBI) membranes doped with different concentrations of KOH are analyzed. Linear membranes show stability up to 3.0 mol·dm-3 KOH doping, while cross-linked membranes are stable up to 4.2 mol·dm-3 KOH doping. Both kinds of membranes exhibit good thermal stability and reasonable specific ionic conductivity at 22 °C in the range between 7 and 25 mS·cm-1, being slightly higher the conductivity of C-ABPBI membranes than that of L-ABPBI ones. In short-term electrolysis tests both L-ABPBI and C-ABPBI membranes show better performance than Zirfon diaphragm in the range from 50 to 70 °C. A current density of 335 mA·cm-2 at a cell voltage of 2.0 V is attained with C-ABPBI membranes doped in 3 mol·dm-3 KOH at 70 °C, a performance comparable with that of commercial units operating at temperatures ca. 80 °C and 30 wt% KOH (6.7 mol·dm-3) as electrolyte.

  13. Blood compatibility of thermoplastic polyurethane membrane immobilized with water-soluble chitosan/dextran sulfate.

    PubMed

    Lin, Wen-Ching; Yu, Da-Guang; Yang, Ming-Chien

    2005-08-01

    Water-soluble chitosan (WSC)/dextran sulfate (DS) was immobilized onto the surface of thermoplastic polyurethane (TPU) membrane after ozone-induced graft polymerization of poly(acrylic acid) (PAA). The surface was characterized with contact angle measurement and X-ray photoelectron spectroscopy (XPS). The adsorption of human plasma fibrinogen (HPF) followed the Langmuir adsorption isotherm. The results showed that the surface density of peroxides generated and poly(acrylic acid) (PAA) grafted reached the maximum value at 20 min of ozone treatment. It was found that the WSC- and DS-immobilized amount increased with pH and the molecular weight of WSC. The membrane/water interfacial free energy increased with PAA-grafting and WSC/DS-immobilization, indicating the increasing wettability of TPU membrane. The adsorption of HPF on TPU-WSC/DS membranes could be effectively curtailed and exhibited unfavorable adsorption. Moreover, WSC/DS immobilization could effectively reduce platelet adhesion and prolong the blood coagulation time, thereby membrane improving blood compatibility of TPU membrane. In addition, the in vitro cytotoxicity test of PEC modification was non-cytotoxic according to much low growth inhibition of L929 fibroblasts. Furthermore, TPU-WSC/DS membranes exhibited higher cell viability than native TPU membrane.

  14. Slow solvation dynamics in the microheterogeneous water channels of nafion membranes.

    PubMed

    Burai, Tarak Nath; Datta, Anindya

    2009-12-10

    Solvation dynamics in Nafion membrane is studied using the well-known solvation probe, coumarin 102 (C102). In native Nafion membrane, the fluorescence maximum of C102 occurs at 525 nm. The decays recorded at different wavelengths are superimposable. There is no time-dependent Stokes shift (TDSS) in the time scale of the experiment. This is rationalized in light of the strongly acidic environment in Nafion membrane, which causes the C102 molecules to become protonated. The protonated molecules are bound tightly to the negatively charged sulfonate groups. In Na(+)- and Me(4)N(+)-exchanged Nafion membranes, the fluorescence gets blue-shifted by 65 nm, indicating the deprotonation of the cation and formation of neutral C102 in these membranes. TDSS is observed in the picosecond-nanosecond time scale, in the cation-exchanged Nafion membranes, although the amount of Stokes' shift is rather small, as compared to that observed in organic solvents, indicating that a significant amount of the solvation is ultrafast and is missed in the present experiment. The observed solvation dynamics is bimodal with fast ( approximately 1 ns) and slow (>10 ns) components. The ultraslow component is ascribed to the quasi-static water molecules in the Nafion membrane. The difference in the extents of apparently missing ultrafast components, between Me(4)N(+)- and Na(+)-substituted membranes is rationalized by a model involving the difference in distributions of the cations in the water channel.

  15. Preparation of hydrophilic nanofiltration membranes for removal of pharmaceuticals from water.

    PubMed

    Omidvar, Maryam; Soltanieh, Mohammad; Mousavi, Seyed Mahmoud; Saljoughi, Ehsan; Moarefian, Ahmad; Saffaran, Hoda

    2015-01-01

    Asymmetric polyethersulfone (PES) nanofiltration membranes were prepared via phase inversion technique. PES polymer, Brij 58 as surfactant additive, polyvinylpyrrolidone (PVP) as pore former and 1-methyl-2-pyrrolidone (NMP) as solvent were used in preparation of the casting solutions. Distillated water was used as the gelation media. The scanning electron microscopy (SEM) images and measurements of contact angle (CA) and zeta potential were used to characterize the prepared membranes. Also performance of the membranes was examined by determining the pure water flux (PWF) and pharmaceuticals rejection. The addition of Brij 58 to the casting solution resulted in formation of the membranes with higher thickness and more porous structure in the sublayer in comparison with the net PES membrane. The surface hydrophilicity of the membranes was remarkably enhanced via the presence of Brij 58 in the casting solution, so that, the contact angel diminished from 74.7° to 28.3° with adding 6 wt. % of Brij 58 to the casting solution. The addition of Brij 58 to the casting solution resulted in formation of the membranes with superior PWF and higher rejection of amoxicillin and ceftriaxone in comparison with the pure PES membrane.

  16. Robust Thermoresponsive Polymer Composite Membrane with Switchable Superhydrophilicity and Superhydrophobicity for Efficient Oil-Water Separation.

    PubMed

    Ou, Ranwen; Wei, Jing; Jiang, Lei; Simon, George P; Wang, Huanting

    2016-01-19

    Herein, we report for the first time on the fabrication of a robust, thermoresponsive polymer membrane produced by the combination of an elastic polyurethane (TPU) microfiber web and poly(N-isopropylacrylamide) (PNIPAM). PNIPAM hydrogel is evenly coated on the surface of TPU microfibers, and thus, the wettability of TPU-PNIPAM membrane is amplified by taking advantage of the hierarchical structure and increased surface roughness. The TPU-PNIPAM membrane possesses switchable superhydrophilicity and superhydrophobicity as the temperature of membrane changes from 25 to 45 °C. The composite membrane is shown successfully able to separate a 1 wt % oil-in-water emulsion and 1 wt % water-in-oil emulsion at 25 and 45 °C, respectively, with a high separation efficiency of ≥99.26%. Furthermore, the composite membranes show excellent mechanical properties, and they are highly flexible and mechanically tough. The smart composite membranes reported here have shown great potential for further development for practical high-efficiency oil-water separations.

  17. Membrane fouling in ultrafiltration of natural water after pretreatment to different extents.

    PubMed

    Ao, Lu; Liu, Wenjun; Zhao, Lin; Wang, Xiaomao

    2016-05-01

    The combined fouling during ultrafiltration (UF) of surface water pretreated to different extents was investigated to disclose the roles of polysaccharides, proteins, and inorganic particles in UF membrane fouling. Both reversible and irreversible fouling decreased with enhanced pretreatment (biologically active carbon (BAC) treatment and sand filtration). The sand filter effluent fouled the membrane very slowly. The UF membrane removed turbidity to less than 0.1 nephelometric turbidity unit (NTU), reduced polysaccharides by 25.4%-29.9%, but rejected few proteins. Both polysaccharides and inorganic particles were detected on the fouled membranes, but inorganic particles could be effectively removed by backwashing. The increase of turbidity in the sand filter effluent to 3.05 NTU did not significantly increase the fouling rate, but an increase in the turbidity in the BAC effluent to 6.11 NTU increased the fouling rate by more than 100%. The results demonstrated that the polysaccharide, not the protein, constituents of biopolymers were responsible for membrane fouling. Membrane fouling was closely associated with a small fraction of polysaccharides in the feed water. Inorganic particles exacerbated membrane fouling only when the concentration of fouling-inducing polysaccharides in the feed water was relatively high. The combined fouling was largely reversible, and polysaccharides were the predominant substances responsible for irreversible fouling.

  18. Novel nanocomposite Kevlar fabric membranes: Fabrication characterization, and performance in oil/water separation

    NASA Astrophysics Data System (ADS)

    Karimnezhad, Hanieh; Rajabi, Laleh; Salehi, Ehsan; Derakhshan, Ali Ashraf; Azimi, Sara

    2014-02-01

    Nanocomposite membranes with hydrophilic surface were fabricated for separation of oil (n-hexane) from oil/water emulsion. Three different nanomaterials namely, para-aminobenzoate alumoxane (PAB-A), boehmite-epoxide and polycitrate alumoxane (PC-A) were coated on the Kevlar fabric (support), according to a three-step dip-coating protocol. FTIR, SEM, TEM, UV/vis spectrophotometer, and wettability analyses were used to characterize the composite membranes. The three coating layers interacted chemically with one another and also physically with the Kevlar fabric. Water uptake measurements indicated that the membrane is a hydrophilic one. SEM and TEM analyses showed the smooth surface of the composite membrane and three-dimensional dendrimeric hyper-branched structure of (PC-A), respectively. A dead-end filtration setup was applied to test the membranes performance under natural gravity force. Effect of pH as an important variable affecting separation process was investigated with the neutral pH provided the optimum condition for the separation. Oil rejection and permeate fluxes were also monitored. The optimum flux and rejection obtained, were 7392 (Lm-2 h-1) and 89.06% at pH 7, respectively. Fouling occurred as a gel layer on the membrane surface. The deposited oil droplets on the surface of the membrane were successfully washed away with satisfactory permeate flux recovery (FRR = 88.88% at neutral pH), using hot distilled water and acidic solution as eluents.

  19. Cost factors and chemical pretreatment effects in the membrane filtration of waters containing natural organic matter.

    PubMed

    Schäfer, A I; Fane, A G; Waite, T D

    2001-04-01

    This paper compares the membrane processes available for water treatment. Membranes have the advantage of currently decreasing capital cost, a relatively small footprint compared to conventional treatment, generally a reduction in chemicals usage and comparably low maintenance requirements. Three membrane processes applicable to water treatment, micro- (MF), ultra- (UF), and nanofiltration (NF), are compared in terms of intrinsic rejection, variation of rejection due to membrane fouling and increase in rejection by ferric chloride pretreatment. Twelve different membranes are compared on the basis of their membrane pore size which was calculated from their molecular weight cut-off. A pore size of < 6 nm is required to achieve substantial (> 50%) organics removal. For a fouled membrane this pore size is about 11 nm. UV rejection is higher than DOC rejection. Coagulation pretreatment allows a higher rejection of organics by MF and UF and the cut-off criterion due to initial membrane pore size is no longer valid. A water quality parameter (WQP) is introduced which describes the product water quality achieved as a function of colloid, DOC and cation rejection. The relationship between log (pore size) and WQP is linear. Estimation of membrane costs as a function of WQP suggests that open UF is superior to MF (similar cost at higher WQP) and NF is superior to tight UF. Chemical pretreatment could compensate for the difference between MF and UF. However, when considering chemicals and energy costs, it appears that a process operated at a higher energy is cheaper at a guaranteed product quality (less dependent on organic type). This argument is further supported by environmental issues of chemicals usage, as energy may be provided from renewable sources.

  20. Development of a hybrid ozonation biofilm-membrane filatration process for the production of drinking water.

    PubMed

    Leiknes, T; Lazarova, M; Odegaard, H

    2005-01-01

    Drinking water sources in Norway are characterized by high concentrations of natural organic matter (NOM), low alkalinity and low turbidity. The removal of NOM is therefore a general requirement in producing potable water. Drinking water treatment plants are commonly designed with coagulation direct filtration or NF spiral wound membrane processes. This study has investigated the feasibility and potential of a hybrid process combining ozonation and biofiltration with a rotating disk membrane for treating drinking water with high NOM concentrations. Ozonation will oxidize the NOM content removing colour and form biodegradable organic compounds, which can be removed in biological filters. A constructed water was used in this study which is representative of ozonated NOM-containing water. A rotating membrane disk bioreactor downstream the ozonation process was used to carry out both the biodegradation as well as biomass separation in the same reactor. Maintenance of biodegradation of the organic matter while controlling biofouling of the membrane and acceptable water production rates was the focus in the study. Three operating modes were investigated. Removal of the biodegradable organics was consistent throughout the study indicating that sufficient biomass was maintained in the reactor for all operating conditions tested. Biofouling control was not achieved through shear-induced cleaning by periodically rotating the membrane disks at high speed. By adding a small amount of sponges in the membrane chamber the biofouling could be controlled by mechanical cleaning of the membrane surface during disk rotation. The overall results indicate that the system can favorably be used in an ozonation/biofiltration process by carrying out both biodegradation as well as biomass separation in the same reactor.

  1. Evolution of water sorption in catalyst coated membranes subjected to combined chemical and mechanical degradation.

    PubMed

    Venkatesan, Senthil velan; Lim, Chan; Rogers, Erin; Holdcroft, Steven; Kjeang, Erik

    2015-06-07

    Catalyst coated perfluorosulfonic acid ionomer membranes (CCMs) were subjected to a combined chemical/mechanical accelerated stress test (AST) designed for rapid benchmarking of in situ membrane stability in polymer electrolyte fuel cells. In order to understand the evolution of the ionomer water sorption characteristics during combined chemical/mechanical degradation, CCM samples were periodically extracted from the AST and analyzed for ionomer mass fraction and water sorption properties. In spite of severe fluoride release and membrane thinning, the water uptake per unit mass of the partially degraded CCMs was found to be essentially constant. The mass fraction of ionomer in the CCM samples determined from thermogravimetric analysis (TGA) showed significant material loss throughout the AST process due to ionomer degradation and fluoride release, up to roughly 50% at end-of-life. The effects proceeding at different stages of degradation were therefore more accurately revealed by ionomer mass-normalized data. The water uptake per unit gram of ionomer was shown to increase significantly with degradation, in contrast to the previous results normalized by CCM dry mass. Although increased water sorption may indicate enlarged solvated hydrophilic domains in the membrane, which would be beneficial for enhanced proton mobility, the proton conductivity was found to decrease. This finding suggests that the additional water sorbed in the membrane was not contributing to proton conduction and was therefore likely situated in non-ionic cavities formed through degradation rather than in the ionic clusters.

  2. Application of forward osmosis membrane technology for oil sands process-affected water desalination.

    PubMed

    Jiang, Yaxin; Liang, Jiaming; Liu, Yang

    2016-01-01

    The extraction process used to obtain bitumen from the oil sands produces large volumes of oil sands process-affected water (OSPW). As a newly emerging desalination technology, forward osmosis (FO) has shown great promise in saving electrical power requirements, increasing water recovery, and minimizing brine discharge. With the support of this funding, a FO system was constructed using a cellulose triacetate FO membrane to test the feasibility of OSPW desalination and contaminant removal. The FO systems were optimized using different types and concentrations of draw solution. The FO system using 4 M NH4HCO3 as a draw solution achieved 85% water recovery from OSPW, and 80 to 100% contaminant rejection for most metals and ions. A water backwash cleaning method was applied to clean the fouled membrane, and the cleaned membrane achieved 77% water recovery, a performance comparable to that of new FO membranes. This suggests that the membrane fouling was reversible. The FO system developed in this project provides a novel and energy efficient strategy to remediate the tailings waters generated by oil sands bitumen extraction and processing.

  3. Infrared spectral marker bands characterizing a transient water wire inside a hydrophobic membrane protein

    SciTech Connect

    Wolf, Steffen; Gerwert, Klaus; Freier, Erik; Cui, Qiang

    2014-12-14

    Proton conduction along protein-bound “water wires” is an essential feature in membrane proteins. Here, we analyze in detail a transient water wire, which conducts protons via a hydrophobic barrier within a membrane protein to create a proton gradient. It is formed only for a millisecond out of three water molecules distributed at inactive positions in a polar environment in the ground state. The movement into a hydrophobic environment causes characteristic shifts of the water bands reflecting their different chemical properties. These band shifts are identified by time-resolved Fourier Transform Infrared difference spectroscopy and analyzed by biomolecular Quantum Mechanical/Molecular Mechanical simulations. A non-hydrogen bonded (“dangling”) O–H stretching vibration band and a broad continuum absorbance caused by a combined vibration along the water wire are identified as characteristic marker bands of such water wires in a hydrophobic environment. The results provide a basic understanding of water wires in hydrophobic environments.

  4. Model-Based Design of Energy Efficient Palladium Membrane Water Gas Shift Fuel Processors for PEM Fuel Cell Power Plants

    NASA Astrophysics Data System (ADS)

    Gummalla, Mallika; Vanderspurt, Thomas Henry; Emerson, Sean; She, Ying; Dardas, Zissis; Olsommer, Benoît

    An integrated, palladium alloy membrane Water-Gas Shift (WGS) reactor can significantly reduce the size, cost and complexity of a fuel processor for a Polymer Electrolyte Membrane fuel cell power system.

  5. Lifting speed preferences and their effects on the maximal lifting capacity

    PubMed Central

    LIN, Chiuhsiang Joe; CHENG, Chih-Feng

    2016-01-01

    The objectives of this study were to evaluate how lifting capacity and subjective preferences are affected by different lifting speeds. The maximum lifting capacity of lift was determined with three independent variables, lifting speed, lifting technique, and lifting height. Questionnaires were evaluated after the experiment by the participants for the lifting speed preferences. This study found that the lifting speed was a significant factor in the lifting capacity (p<0.001); and the lifting height (p<0.001) and the interaction of lifting speed and lifting height (p=0.005) affected the lifting capacity significantly. The maximal lifting capacity was achieved around the optimal speed that was neither too fast nor too slow. Moreover, the participants’ preferred lifting speeds were consistently close to the optimal lifting speed. The results showed that the common lifting practice guideline to lift slowly might make the worker unable to generate a large lifting capacity. PMID:27383532

  6. Lifting speed preferences and their effects on the maximal lifting capacity.

    PubMed

    Lin, Chiuhsiang Joe; Cheng, Chih-Feng

    2017-02-07

    The objectives of this study were to evaluate how lifting capacity and subjective preferences are affected by different lifting speeds. The maximum lifting capacity of lift was determined with three independent variables, lifting speed, lifting technique, and lifting height. Questionnaires were evaluated after the experiment by the participants for the lifting speed preferences. This study found that the lifting speed was a significant factor in the lifting capacity (p<0.001); and the lifting height (p<0.001) and the interaction of lifting speed and lifting height (p=0.005) affected the lifting capacity significantly. The maximal lifting capacity was achieved around the optimal speed that was neither too fast nor too slow. Moreover, the participants' preferred lifting speeds were consistently close to the optimal lifting speed. The results showed that the common lifting practice guideline to lift slowly might make the worker unable to generate a large lifting capacity.

  7. USE OF MEMBRANE BIOREACTOR FOR BIODEGRADATION OF MTBE IN CONTAMINATED WATER1

    EPA Science Inventory

    An ultrafiltration membrane bioreactor was evaluated for biodegradation of methyl tert-butyl ether (MTBE) in contaminated water. The system was fed 5 mg/L MTBE in granular activated carbon (GAC) treated Cincinnati tap water containing ample buffer and nutrients. Within 120...

  8. Small Water System Alternatives: Media and Membrane Filtration Alternatives for Small Communities and Households

    EPA Science Inventory

    This webinar presentation will highlight research case studies on innovative drinking water treatment alternatives for small community water systems. Emphasis will be placed on media and membrane filtration technologies capable of meeting the requirements of the Long-Term 2 Enha...

  9. Transport Membrane Condenser for Water and Energy Recovery from Power Plant Flue Gas

    SciTech Connect

    Dexin Wang

    2012-03-31

    The new waste heat and water recovery technology based on a nanoporous ceramic membrane vapor separation mechanism has been developed for power plant flue gas application. The recovered water vapor and its latent heat from the flue gas can increase the power plant boiler efficiency and reduce water consumption. This report describes the development of the Transport Membrane Condenser (TMC) technology in details for power plant flue gas application. The two-stage TMC design can achieve maximum heat and water recovery based on practical power plant flue gas and cooling water stream conditions. And the report includes: Two-stage TMC water and heat recovery system design based on potential host power plant coal fired flue gas conditions; Membrane performance optimization process based on the flue gas conditions, heat sink conditions, and water and heat transport rate requirement; Pilot-Scale Unit design, fabrication and performance validation test results. Laboratory test results showed the TMC system can exact significant amount of vapor and heat from the flue gases. The recovered water has been tested and proved of good quality, and the impact of SO{sub 2} in the flue gas on the membrane has been evaluated. The TMC pilot-scale system has been field tested with a slip stream of flue gas in a power plant to prove its long term real world operation performance. A TMC scale-up design approach has been investigated and an economic analysis of applying the technology has been performed.

  10. Underwater self-cleaning scaly fabric membrane for oily water separation.

    PubMed

    Zheng, Xi; Guo, Zhenyan; Tian, Dongliang; Zhang, Xiaofang; Li, Wenxian; Jiang, Lei

    2015-02-25

    Oily wastewater is always a threat to biological and human safety, and it is a worldwide challenge to solve the problem of disposing of it. The development of interface science brings hope of solving this serious problem, however. Inspired by the capacity for capturing water of natural fabrics and by the underwater superoleophobic self-cleaning property of fish scales, a strategy is proposed to design and fabricate micro/nanoscale hierarchical-structured fabric membranes with superhydrophilicity and underwater superoleophobicity, by coating scaly titanium oxide nanostructures onto fabric microstructures, which can separate oil/water mixtures efficiently. The microstructures of the fabrics are beneficial for achieving high water-holding capacity of the membranes. More importantly, the special scaly titanium oxide nanostructures are critical for achieving the desired superwetting property toward water of the membranes, which means that air bubbles cannot exist on them in water and there is ultralow underwater-oil adhesion. The cooperative effects of the microscale and nanoscale structures result in the formation of a stable oil/water/solid triphase interface with a robust underwater superoleophobic self-cleaning property. Furthermore, the fabrics are common, commercially cheap, and environmentally friendly materials with flexible but robust mechanical properties, which make the fabric membranes a good candidate for oil/water separation even under strong water flow. This work would also be helpful for developing new underwater superoleophobic self-cleaning materials and related devices.

  11. Polyaniline coated membranes for effective separation of oil-in-water emulsions.

    PubMed

    Liu, Mingming; Li, Jing; Guo, Zhiguang

    2016-04-01

    Polyaniline (PANI) decorated commercial filtration membranes, such as stainless steel meshes (SSMs) with 5μm pore size and polyvinylidene fluoride (PVDF) membranes with 2-0.22μm pore sizes, were fabricated by a simple one-step dilute polymerization at low temperature. Lots of short PANI nanofibers were firmly and uniformly coated onto the membrane surfaces, forming rough micro- and nanoscale structures and leading to underwater superoleophobicity with low oil-adhesion characteristic. Furthermore, we systematically studied the effect of pore size and pressure difference on oil-water separation ability of the obtained membranes. It was found that the PANI-modified SSMs with 5μm pore size were suitable for the separation of non-surfactant emulsions with water fluxes of more than 1000Lm(-2)h(-1) under gravity only. The PANI-modified PVDF membranes were used for the effective separation of surfactant-stabilized emulsions with water fluxes up to 3000Lm(-2)h(-1) for 2μm pore size under 0.1bar or 0.22μm pore size under 0.6bar. In addition, the superhydrophilic membranes with PANI coatings were demonstrated for high oil rejection, stable underwater superoleophobic properties after ultrasonic treatment and immersing in oils and various harsh conditions, and high and steady water permeation flux after several cycles.

  12. Study of antifouling modified ultrafiltration membrane based on the secondary treated water of urban sewage.

    PubMed

    Meng, Xiao-rong; Zhao, Liang; Wang, Lei; Wang, Xu-dong; Huang, Dan-xi; Miao, Rui

    2012-01-01

    Mixtures of polyvinylidene fluoride (PVDF) and polyvinyl alcohol (PVA) containing hydrophilic ultrafiltration membranes were prepared by adding PVA (5 to 30%) to PVDF by the phase inversion method. The hydrophilic contact angle (CA), equilibrium water content, pure water flux and bovine serum albumin retention were studied to assess the membrane performance. The anti-fouling performance of modified membrane to the secondary treated water was evaluated by flux decline, washing recovery rate and fouling resistance analysis. Scanning electron microscopy showed that the cross-section structure of the membranes had finger-like pores, which were well developed and uniformly distributed, and the sub-layer structure was looser and more porous with the increasing content of PVA. The CA gradually decreased. The steady flux was 800 L/m(2) h from P15 to P30, and the BSA retention sharply declined. The ultrafiltration tests for secondary treated water indicated that the main fouling source of the modified membrane was the concentration polarization and cake layer resistance. After physical flushing, the flux recovery ratio of the membrane could reach 100% when the PVA content was 5-15%, which shows excellent anti-pollution performance and good prospects for use in processing wastewater from urban sewage.

  13. Near-infrared imaging of water in a polymer electrolyte membrane during a fuel cell operation.

    PubMed

    Morita, Shigeaki; Jojima, Yuki; Miyata, Yasushi; Kitagawa, Kuniyuki

    2010-11-15

    A novel technique of spectroscopic imaging using a near-infrared (NIR) laser sheet beam was developed for visualization of liquid water in a proton-exchange membrane (PEM) sandwiched between two opaque electrodes set in a polymer electrolyte fuel cell (PEFC). In-plane two-dimensional distribution of water in the thin membrane was clearly visualized during the fuel cell operation. Under the condition of fuel feeding into the PEFC without humidification, water was generated by the fuel cell reaction in the whole electrode area. In contrast, under the condition of fuel feeding with humidification, the PEM got wet in the vicinity of a gas flow field locally.

  14. Quantitation of water in membranes by neutron diffraction and X-ray techniques

    SciTech Connect

    Knott, R.B.; Schoenborn, B.P.

    1986-01-01

    The general principle of placing neutron and X-ray scattering density profiles on an absolute scale is being applied to an increasing number of problems in structural biology. This maximizes the information from the experiments by facilitating the identification of various molecular species. The greater detail available on the membrane water distribution has been highlighted in this chapter. The quantitative analysis of water in the headgroup region and the intermembrane water layer provides valuable information on membrane structure and function. The single most important limitation of the method is the lack of resolution. Improvements in experimental techniques will improve the resolution in a number of situations.

  15. Helicopter Toy and Lift Estimation

    ERIC Educational Resources Information Center

    Shakerin, Said

    2013-01-01

    A $1 plastic helicopter toy (called a Wacky Whirler) can be used to demonstrate lift. Students can make basic measurements of the toy, use reasonable assumptions and, with the lift formula, estimate the lift, and verify that it is sufficient to overcome the toy's weight. (Contains 1 figure.)

  16. Reduced Graphene Oxide Bipolar Membranes for Integrated Solar Water Splitting in Optimal pH.

    PubMed

    McDonald, Michael B; Bruce, Jared P; McEleney, Kevin; Freund, Michael S

    2015-08-24

    The integration of light absorbers and catalysts for the water splitting process requires a membrane capable of both ion and electron management and product separation to realize efficient solar fuels systems. Bipolar membranes can maintain a pH gradient for optimal reaction conditions by the dissociation of water. Such membranes that contain graphene in the interfacial layer are fabricated by the chemical reduction of a uniformly deposited graphene oxide layer to convert sp(3) catalyst regions to sp(2) conductive regions. The resulting electrical and water dissociation properties are optimized by adjusting the exposure conditions, and treatments of less than 5 min render an interface that exceeds the conductivity requirements for integrated solar water splitting and increases the overpotential by <0.3 V. Integration with photoelectrodes is examined by characterizing the electrical interface formed between graphene and Si microwires, and we found that efficient Ohmic junctions are possible.

  17. Transport of Water in Semicrystalline Block Copolymer Membranes

    NASA Astrophysics Data System (ADS)

    Hallinan, Daniel; Oparaji, Onyekachi

    Poly(styrene)-block-poly(ethylene oxide) (PS- b-PEO) is a semicrystalline block copolymer (BCP) with interesting properties. It is mechanically tough, amphiphilic, and has a polar phase. The mechanical toughness is due to the crystallinity of PEO and the high glass transition temperature of PS, as well as the morphological structure of the BCP. The polymer has high CO2, water, and salt solubility that derive from the polar PEO component. Potential applications include CO2 separation, water purification, and lithium air batteries. In all of the aforementioned applications, water transport is an important parameter. The presence of water can also affect thermal and mechanical properties. Water transport and thermal and mechanical properties of a lamellar PS- b-PEO copolymer have been measured as a function of water activity. Water transport can be affected by the heterogeneous nature of a semicrystalline BCP. Therefore, Fourier transform infrared - attenuated total reflectance (FTIR-ATR) spectroscopy has been employed, because water transport and polymer swelling can be measured simultaneously. The effect of BCP structure on transport has been investigated by comparing water transport in PS- b-PEO to a PEO homopolymer. The crystalline content of the PEO and the presence of glassy PS lamellae will be used to explain the transport results.

  18. Active Trans-Plasma Membrane Water Cycling in Yeast Is Revealed by NMR

    PubMed Central

    Zhang, Yajie; Poirier-Quinot, Marie; Springer, Charles S.; Balschi, James A.

    2011-01-01

    Plasma membrane water transport is a crucial cellular phenomenon. Net water movement in response to an osmotic gradient changes cell volume. Steady-state exchange of water molecules, with no net flux or volume change, occurs by passive diffusion through the phospholipid bilayer and passage through membrane proteins. The hypothesis is tested that plasma membrane water exchange also correlates with ATP-driven membrane transport activity in yeast (Saccharomyces cerevisiae). Longitudinal 1H2O NMR relaxation time constant (T1) values were measured in yeast suspensions containing extracellular relaxation reagent. Two-site-exchange analysis quantified the reversible exchange kinetics as the mean intracellular water lifetime (τi), where τi−1 is the pseudo-first-order rate constant for water efflux. To modulate cellular ATP, yeast suspensions were bubbled with 95%O2/5%CO2 (O2) or 95%N2/5%CO2 (N2). ATP was high during O2, and τi−1 was 3.1 s−1 at 25°C. After changing to N2, ATP decreased and τi−1 was 1.8 s−1. The principal active yeast ion transport protein is the plasma membrane H+-ATPase. Studies using the H+-ATPase inhibitor ebselen or a yeast genetic strain with reduced H+-ATPase found reduced τi−1, notwithstanding high ATP. Steady-state water exchange correlates with H+-ATPase activity. At volume steady state, water is cycling across the plasma membrane in response to metabolic transport activity. PMID:22261073

  19. Recent Trends in Nanofibrous Membranes and Their Suitability for Air and Water Filtrations

    PubMed Central

    Balamurugan, Ramalingam; Sundarrajan, Subramanian; Ramakrishna, Seeram

    2011-01-01

    In recent decades, engineered membranes have become a viable separation technology for a wide range of applications in environmental, food and biomedical fields. Membranes are now competitive compared to conventional techniques such as adsorption, ion exchangers and sand filters. The main advantage of membrane technology is the fact that it works without the addition of any chemicals, with relatively high efficiency and low energy consumption with well arranged process conductions. Hence they are widely utilized in biotechnology, food and drink manufacturing, air filtration and medical uses such as dialysis for kidney failure patients. Membranes from nanofibrous materials possess high surface area to volume ratio, fine tunable pore sizes and their ease of preparation prompted both industry and academic researchers to study their use in many applications. In this paper, modern concepts and current research progress on various nanofibrous membranes, such as water and air filtration media, are presented. PMID:24957734

  20. Replacement of chemical intensive water treatment processes with energy saving membrane. Final report

    SciTech Connect

    Mickley, M.C.; Goering, S.W.

    1983-11-01

    The project investigated the use of charged ultrafiltration membranes to treat hard water. More specifically, the work was undertaken to (1) make charged ultrafiltration membranes to demonstrate the technical feasibility of the chemical grafting approach; (2) evaluate the market potential for charged ultrafiltration membranes; and (3) evaluate the cost and energy savings for using charged ultrafiltration as compared to lime-based clarification and other treatment methods. The results suggest that chemical grafting is a relatively simple, reproducible and low-cost way to modify existing substrate materials to give them enhanced transport performance. Process studies lead to the identification of good market potential for membrane processes using charged ultrafiltration membranes. Capital and operating costs relative to lime-based clarification are favorable for low- and medium-sized treatment plants. Finally, substantial energy savings are apparent as compared to lime-based precipitation systems which incur substantial energy consumption in the lime production and transportation steps.

  1. The environmental applications and implications of nanotechnology in membrane-based separations for water treatment

    NASA Astrophysics Data System (ADS)

    Shan, Wenqian

    This dissertation presents results of three related projects focused on the applications of membrane separation technology to water treatment: 1) Experimental design and evaluation of polyelectrolyte multilayer films as regenerable membrane coatings with controllable surface properties; 2) Modeling of the interactions of nanoscale TiO2 and NOM molecules in aqueous solutions of environmentally relevant compositions; 3) Experimental design and preliminary testing of a membrane-based crossflow filtration hydrocyclone process for the separation of oil-in-water dispersions. Chapter 2 describes the design of polyelectrolyte multilayers as nanoscale membrane coatings and their application in nanofiltration of feed waters that contain suspended colloids and dissolved species. Layer-by-layer deposition of anionic and cationic polyelectrolytes was employed to prepare membrane coatings allowing for a fine control over their surface properties. This approach to membrane design also affords a possibility of regenerating coatings after they are fouled by colloids. This project demonstrated, for first time, the possibility of designing nanofiltration membranes with regenerable skin. Chapter 3 describes a study on the mechanisms of natural organic matter (NOM) adsorption onto the surface of titania nanoparticles. Titainia (TiO 2) is often used in the fabrication of ceramic membranes and understanding how NOM interacts with TiO2 can help to better predict ceramic membrane fouling by NOM-containing waters. The combined effect of pH and calcium on the interactions of nonozonated and ozonated NOM with nanoscale TiO 2 was investigated by applying extended Derjaguin --- Landau --- Verwey - Overbeek (XDLVO) modeling. XDLVO surface energy analysis predicted NOM adsorption onto TiO2 in the ozone-controlled regime but not in the calcium-controlled regime. In both regimes, short range NOM-NOM and NOM-TiO2 interactions were governed by acid-base and van der Waals forces, whereas the role of

  2. Silicone Membranes to Inhibit Water Uptake into Thermoset Polyurethane Shape-Memory Polymer Conductive Composites.

    PubMed

    Yu, Ya-Jen; Infanger, Stephen; Grunlan, Melissa A; Maitland, Duncan J

    2015-01-05

    Electroactive shape memory polymer (SMP) composites capable of shape actuation via resistive heating are of interest for various biomedical applications. However, water uptake into SMPs will produce a depression of the glass transition temperature (Tg ) resulting in shape recovery in vivo. While water actuated shape recovery may be useful, it is foreseen to be undesirable during early periods of surgical placement into the body. Silicone membranes have been previously reported to prevent release of conductive filler from an electroactive polymer composite in vivo. In this study, a silicone membrane was used to inhibit water uptake into a thermoset SMP composite containing conductive filler. Thermoset polyurethane (PU) SMPs were loaded with either 5 wt% carbon black (CB) or 5 wt% carbon nanotubes (CNT) and subsequently coated with either an Al2O3- or silica-filled silicone membrane. It was observed that the silicone membranes, particularly the silica-filled membrane, reduced the rate of water absorption (37 °C) and subsequent Tg depression versus uncoated composites. In turn, this led to a reduction in the rate of recovery of the permanent shape when exposed to water at 37 °C.

  3. Natural clinoptilolite composite membranes on tubular stainless steel supports for water softening.

    PubMed

    Adamaref, Solmaz; An, Weizhu; Jarligo, Maria Ophelia; Kuznicki, Tetyana; Kuznicki, Steven M

    2014-01-01

    Disk membranes generated from high-purity natural clinoptilolite mineral rock have shown promising water desalination and de-oiling performance. In order to scale up production of these types of membranes for industrial wastewater treatment applications, a coating strategy was devised. A composite mixture of natural clinoptilolite from St. Cloud (Winston, NM, USA) and aluminum phosphate was deposited on the inner surface of porous stainless steel tubes by the slip casting technique. The commercial porous stainless steel tubes were pre-coated with a TiO2 layer of about 10 μm. Phase composition and morphology of the coating materials were investigated using X-ray diffraction and scanning electron microscopy. Water softening performance of the fabricated membranes was evaluated using Edmonton (Alberta, Canada) municipal tap water as feed source. Preliminary experimental results show a high water flux of 7.7 kg/(m(2) h) and 75% reduction of hardness and conductivity in a once-through membrane process at 95 °C and feed pressure of 780 kPa. These results show that natural zeolite coated, stainless steel tubular membranes have high potential for large-scale purification of oil sands steam-assisted gravity drainage water at high temperature and pressure requirements.

  4. Silicone Membranes to Inhibit Water Uptake into Thermoset Polyurethane Shape-Memory Polymer Conductive Composites

    PubMed Central

    Yu, Ya-Jen; Infanger, Stephen; Grunlan, Melissa A.; Maitland, Duncan J.

    2014-01-01

    Electroactive shape memory polymer (SMP) composites capable of shape actuation via resistive heating are of interest for various biomedical applications. However, water uptake into SMPs will produce a depression of the glass transition temperature (Tg) resulting in shape recovery in vivo. While water actuated shape recovery may be useful, it is foreseen to be undesirable during early periods of surgical placement into the body. Silicone membranes have been previously reported to prevent release of conductive filler from an electroactive polymer composite in vivo. In this study, a silicone membrane was used to inhibit water uptake into a thermoset SMP composite containing conductive filler. Thermoset polyurethane (PU) SMPs were loaded with either 5 wt% carbon black (CB) or 5 wt% carbon nanotubes (CNT) and subsequently coated with either an Al2O3- or silica-filled silicone membrane. It was observed that the silicone membranes, particularly the silica-filled membrane, reduced the rate of water absorption (37 °C) and subsequent Tg depression versus uncoated composites. In turn, this led to a reduction in the rate of recovery of the permanent shape when exposed to water at 37 °C. PMID:25663711

  5. A water and heat management model for proton-exchange-membrane fuel cells

    SciTech Connect

    Nguyen, T.V.; White, R.E. . Dept. of Chemical Engineering)

    1993-08-01

    Proper water and heat management are essential for obtaining high-power-density performance at high energy efficiency for proton-exchange-membrane fuel cells. A water and heat management model was developed and used to investigate the effectiveness of various humidification designs. The model accounts for water transport across the membrane by electro-osmosis and diffusion, heat transfer from the solid phase to the gas phase and latent heat associated with water evaporation and condensation in the flow channels. Results from the model showed that at high current (> 1A/cm[sup 2]) ohmic loss in the membrane accounts for a large fraction of the voltage loss in the cell and back diffusion of water from the cathode side of the membrane is insufficient to keep the membrane hydrated (i.e., conductive). Consequently, to minimize this ohmic loss the anode stream must be humidified, and when air is used instead of pure oxygen the cathode stream must also be humidified.

  6. Application of membrane filters for spectrophotometric determination of cationic surfactants in river water and sediment.

    PubMed

    Huij-Feng, S; Takamori, M; Hata, N; Kasahara, I; Taguchi, S

    2001-01-01

    Cationic surfactant (CS+) in urban river water and sediment was extracted and determined spectrophotometrically with 2 membrane filters. The CS+ in the water samples, mostly in the form of an ion associate with the coexisting anionic surfactant (AS), was collected on a polytetrafluoroethylene (PTFE) membrane filter and eluted with methanol. Bromphenol blue (BPB), hydrochloric acid, and water were added to the methanol solution successively, and the mixed solution was filtered through a mixed cellulose ester membrane filter. The CS+-BPB- ion associate, formed by a counter ion exchange, was collected on the filter and dissolved into N,N-dimethylformamide (DMF) together with the mixed cellulose ester membrane filter. After addition of 2 drops of triethanolamine, the absorbance of the DMF solution was measured. The CS+ in sediment samples was extracted with methanol by ultrasonic irradiation; the methanol solution was then passed through a PTFE membrane filter and evaporated to dryness. The CS+ was redissolved in a small amount of methanol. For water samples, recoveries and relative standard deviations for 0.30 microM benzyldimethyl-tetradecylammonium ion, a standard material, were > or =93 and < or =5%, with a detection limit of 0.02 microM. Concentrations of CS+ in sediments were much higher than those in water samples, indicating that CS+ is adsorbed on the surface of the sediment.

  7. Silicone membranes to inhibit water uptake into thermoset polyurethane shape-memory polymer conductive composites

    SciTech Connect

    Yu, Ya-Jen; Infanger, Stephen; Grunlan, Melissa A.; Maitland, Duncan J.

    2014-07-24

    Electroactive shape memory polymer (SMP) composites capable of shape actuation via resistive heating are of interest for various biomedical applications. However, water uptake into SMPs will produce a depression of the glass transition temperature (Tg) resulting in shape recovery in vivo. While water actuated shape recovery may be useful, it is foreseen to be undesirable during early periods of surgical placement into the body. Silicone membranes have been previously reported to prevent release of conductive filler from an electroactive polymer composite in vivo. In this paper, a silicone membrane was used to inhibit water uptake into a thermoset SMP composite containing conductive filler. Thermoset polyurethane SMPs were loaded with either 5 wt % carbon black or 5 wt % carbon nanotubes, and subsequently coated with either an Al2O3- or silica-filled silicone membrane. It was observed that the silicone membranes, particularly the silica-filled membrane, reduced the rate of water absorption (37°C) and subsequent Tg depression versus uncoated composites. Finally, in turn, this led to a reduction in the rate of recovery of the permanent shape when exposed to water at 37°C.

  8. Silicone membranes to inhibit water uptake into thermoset polyurethane shape-memory polymer conductive composites

    DOE PAGES

    Yu, Ya-Jen; Infanger, Stephen; Grunlan, Melissa A.; ...

    2014-07-24

    Electroactive shape memory polymer (SMP) composites capable of shape actuation via resistive heating are of interest for various biomedical applications. However, water uptake into SMPs will produce a depression of the glass transition temperature (Tg) resulting in shape recovery in vivo. While water actuated shape recovery may be useful, it is foreseen to be undesirable during early periods of surgical placement into the body. Silicone membranes have been previously reported to prevent release of conductive filler from an electroactive polymer composite in vivo. In this paper, a silicone membrane was used to inhibit water uptake into a thermoset SMP compositemore » containing conductive filler. Thermoset polyurethane SMPs were loaded with either 5 wt % carbon black or 5 wt % carbon nanotubes, and subsequently coated with either an Al2O3- or silica-filled silicone membrane. It was observed that the silicone membranes, particularly the silica-filled membrane, reduced the rate of water absorption (37°C) and subsequent Tg depression versus uncoated composites. Finally, in turn, this led to a reduction in the rate of recovery of the permanent shape when exposed to water at 37°C.« less

  9. Diffusion of water and selected atoms in DMPC lipid bilayer membranes

    NASA Astrophysics Data System (ADS)

    Hansen, F. Y.; Peters, G. H.; Taub, H.; Miskowiec, A.

    2012-11-01

    Molecular dynamics simulations have been used to determine the diffusion of water molecules as a function of their position in a fully hydrated freestanding 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) bilayer membrane at 303 K and 1 atm. The diffusion rate of water in a ˜10 Å thick layer just outside the membrane surface is reduced on average by a factor of ˜2 relative to bulk. For water molecules penetrating deeper into the membrane, there is an increasing reduction in the average diffusion rate with up to one order of magnitude decrease for those deepest in the membrane. A comparison with the diffusion rate of selected atoms in the lipid molecules shows that ˜6 water molecules per lipid molecule move on the same time scale as the lipids and may therefore be considered to be tightly bound to them. The quasielastic neutron scattering functions for water and selected atoms in the lipid molecule have been simulated and compared to observed quasielastic neutron scattering spectra from single-supported bilayer DMPC membranes.

  10. Spontaneous water filtration of bio-inspired membrane

    NASA Astrophysics Data System (ADS)

    Kim, Kiwoong; Kim, Hyejeong; Lee, Sang Joon

    2016-11-01

    Water is one of the most important elements for plants, because it is essential for various metabolic activities. Thus, water management systems of vascular plants, such as water collection and water filtration have been optimized through a long history. In this view point, bio-inspired technologies can be developed by mimicking the nature's strategies for the survival of the fittest. However, most of the underlying biophysical features of the optimized water management systems remain unsolved In this study, the biophysical characteristics of water filtration phenomena in the roots of mangrove are experimentally investigated. To understand water-filtration features of the mangrove, the morphological structures of its roots are analyzed. The electrokinetic properties of the root surface are also examined. Based on the quantitatively analyzed information, filtration of sodium ions in the roots are visualized. Motivated by this mechanism, spontaneous desalination mechanism in the root of mangrove is proposed by combining the electrokinetics and hydrodynamic transportation of ions. This study would be helpful for understanding the water-filtration mechanism of the roots of mangrove and developing a new bio-inspired desalination technology. This research was financially supported by the National Research Foundation (NRF) of Korea (Contract Grant Number: 2008-0061991).

  11. Determination of water content and resistivity of perfluorosulfonic acid fuel cell membranes

    SciTech Connect

    Sen, A.; Leach, K.E.; Varjian, R.D.

    1995-12-31

    Water uptake and resistivity have been determined for Dupont`s Nafion-115{reg_sign} and Dow membrane 800 EW while in contact with a water-saturated nitrogen atmosphere using fourier transform near-infrared (NIR), and AC impedance four point techniques in the temperature range of 23 C to 100 C. Results show that at room temperature there is a significant increase in water content and a corresponding decrease in the electrical resistivity as the relative humidity increases from 0% to 100%. Results also indicate that there is a substantial decrease in water uptake from water vapor at 100 C relative to that at 23 C. The water contents of Dow PFSA 800 EW and Nafion-115 membranes at about 92% R.H. and 23 C are approximately 25 wt% and 18 wt%, respectively. The corresponding water content values at 100 C are 10 wt% and 8 wt%, respectively. The resistivity of the membranes decreases sharply with the temperature up to 60 C, reaches a minimum near 80 C then increases up to 100 C. The Dow membrane has lower resistivity than Nafion-115 over the entire range.

  12. Selective separation of oil and water with mesh membranes by capillarity.

    PubMed

    Yu, Yuanlie; Chen, Hua; Liu, Yun; Craig, Vincent S J; Lai, Zhiping

    2016-09-01

    The separation of oil and water from wastewater generated in the oil-production industries, as well as in frequent oil spillage events, is important in mitigating severe environmental and ecological damage. Additionally, a wide arrange of industrial processes require oils or fats to be removed from aqueous systems. The immiscibility of oil and water allows for the wettability of solid surfaces to be engineered to achieve the separation of oil and water through capillarity. Mesh membranes with extreme, selective wettability can efficiently remove oil or water from oil/water mixtures through a simple filtration process using gravity. A wide range of different types of mesh membranes have been successfully rendered with extreme wettability and applied to oil/water separation in the laboratory. These mesh materials have typically shown good durability, stability as well as reusability, which makes them promising candidates for an ever widening range of practical applications.

  13. Structure and functions of simple membrane-water interfaces. [Abstract only

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Wilson, M. A.

    1994-01-01

    The structure and functions of the earliest ancestors of contemporary cells are focal points in studies of the origin of life. Probably the first cell-like structures were vesicles - closed, spheroidal structures with aqueous medium trapped inside. The membranous walls of vesicles were most likely bilayers composed of simple amphiphilic material available on early earth. The membrane studied was composed of glycerol 1-monooleate (GMO). Glycerol forms the polar head group and the oily tail contains 18 carbon atoms. All head groups have been found to be located in two narrow regions at the interfaces with water. The membrane interior, formed by the hydrophobic tails, is quite fluid with chain disorder increasing towards the center of the bilayer. These results are in agreement with x-ray and neutron scattering data from related bilayers. The width of the membrane is not constant, but fluctuates in time and space. Occasional thinning defects in the membrane, observed during the course of the simulations, may have a significant influence on rates of passive transport of small molecules across membranes. It has been found that water penetrates the head group region but not the oily interior of the membrane. Water molecules near the interface are oriented by dipoles of the head groups. The resulting electrostatic potential across the interface, determined in our simulations, has been found to be markedly larger than across the water-oil interface. This quantity has been implicated as the source of selectivity, with respect to the sign of the charge, as an ion approaches the interface and during transport of hydrophobic ions across membranes.

  14. Simulating Mars' Dust Cycle with a Mars General Circulation Model: Effects of Water Ice Cloud Formation on Dust Lifting Strength and Seasonality

    NASA Technical Reports Server (NTRS)

    Kahre, Melinda A.; Haberle, Robert; Hollingsworth, Jeffery L.

    2012-01-01

    The dust cycle is critically important for the current climate of Mars. The radiative effects of dust impact the thermal and dynamical state of the atmosphere [1,2,3]. Although dust is present in the Martian atmosphere throughout the year, the level of dustiness varies with season. The atmosphere is generally the dustiest during northern fall and winter and the least dusty during northern spring and summer [4]. Dust particles are lifted into the atmosphere by dust storms that range in size from meters to thousands of kilometers across [5]. Regional storm activity is enhanced before northern winter solstice (Ls200 degrees - 240 degrees), and after northern solstice (Ls305 degrees - 340 degrees ), which produces elevated atmospheric dust loadings during these periods [5,6,7]. These pre- and post- solstice increases in dust loading are thought to be associated with transient eddy activity in the northern hemisphere with cross-equatorial transport of dust leading to enhanced dust lifting in the southern hemisphere [6]. Interactive dust cycle studies with Mars General Circulation Models (MGCMs) have included the lifting, transport, and sedimentation of radiatively active dust. Although the predicted global dust loadings from these simulations capture some aspects of the observed dust cycle, there are marked differences between the simulated and observed dust cycles [8,9,10]. Most notably, the maximum dust loading is robustly predicted by models to occur near northern winter solstice and is due to dust lifting associated with down slope flows on the flanks of the Hellas basin. Thus far, models have had difficulty simulating the observed pre- and post- solstice peaks in dust loading.

  15. Computational fluid dynamics simulations of membrane filtration process adapted for water treatment of aerated sewage lagoons.

    PubMed

    Cano, Grégory; Mouahid, Adil; Carretier, Emilie; Guasp, Pascal; Dhaler, Didier; Castelas, Bernard; Moulin, Philippe

    2015-01-01

    The aim of this study is to apply the membrane bioreactor technology in an oxidation ditch in submerged conditions. This new wastewater filtration process will benefit rural areas (<5,000 population equivalent) subject to chronic water shortages by reusing this water for irrigation of green areas. For this purpose, the membranes developed without support are immersed in an aeration well and work in suction mode. The development of the membrane without support and more precisely the performance of spacers are approached by computational fluid dynamics in order to provide the best compromise between pressure drop/flow velocity and permeate flux. The numerical results on the layout and the membrane modules' geometry in the aeration well indicate that the optimal configuration is to install the membranes horizontally on three levels. Membranes should be connected to each other to a manifold providing a total membrane area of 18 m². Loss rate compared to the theoretical throughput is relatively low (less than 3%). Preliminary data obtained by modeling the lagoon provide access to its hydrodynamics, revealing that recirculation zones can be optimized by making changes in the operating conditions. The experimental validation of these results and taking into account the aeration in the numerical models are underway.

  16. Chemical and microstructural analyses for heavy metals removal from water media by ceramic membrane filtration.

    PubMed

    Ali, Asmaa; Ahmed, Abdelkader; Gad, Ali

    2017-01-01

    This study aims to investigate the ability of low cost ceramic membrane filtration in removing three common heavy metals namely; Pb(2+), Cu(2+), and Cd(2+) from water media. The work includes manufacturing ceramic membranes with dimensions of 15 by 15 cm and 2 cm thickness. The membranes were made from low cost materials of local clay mixed with different sawdust percentages of 0.5%, 2.0%, and 5.0%. The used clay was characterized by X-ray diffraction (XRD) and X-ray fluorescence analysis. Aqueous solutions of heavy metals were prepared in the laboratory and filtered through the ceramic membranes. The influence of the main parameters such as pH, initial driving pressure head, and concentration of heavy metals on their removal efficiency by ceramic membranes was investigated. Water samples were collected before and after the filtration process and their heavy metal concentrations were determined by chemical analysis. Moreover, a microstructural analysis using scanning electronic microscope (SEM) was performed on ceramic membranes before and after the filtration process. The chemical analysis results showed high removal efficiency up to 99% for the concerned heavy metals. SEM images approved these results by showing adsorbed metal ions on sides of the internal pores of the ceramic membranes.

  17. Hollow fiber membrane decorated with Ag/MWNTs: toward effective water disinfection and biofouling control.

    PubMed

    Gunawan, Poernomo; Guan, Cong; Song, Xianghua; Zhang, Quanyuan; Leong, Susanna Su Jan; Tang, Chuyang; Chen, Yuan; Chan-Park, Mary B; Chang, Matthew Wook; Wang, Kean; Xu, Rong

    2011-12-27

    The currently applied disinfection methods during water treatment provide effective solutions to kill pathogens, but also generate harmful byproducts, which are required to be treated with additional efforts. In this work, an alternative and safer water disinfection system consisting of silver nanoparticle/multiwalled carbon nanotubes (Ag/MWNTs) coated on a polyacrylonitrile (PAN) hollow fiber membrane, Ag/MWNTs/PAN, has been developed. Silver nanoparticles of controlled sizes were coated on polyethylene glycol-grafted MWNTs. Ag/MWNTs were then covalently coated on the external surface of a chemically modified PAN hollow fiber membrane to act as a disinfection barrier. A continuous filtration test using E. coli containing feedwater was conducted for the pristine PAN and Ag/MWNTs/PAN composite membranes. The Ag/MWNT coating significantly enhanced the antimicrobial activities and antifouling properties of the membrane against E. coli. Under the continuous filtration mode using E. coli feedwater, the relative flux drop over Ag/MWNTs/PAN was 6%, which was significantly lower than that over the pristine PAN (55%) at 20 h of filtration. The presence of the Ag/MWNT disinfection layer effectively inhibited the growth of bacteria in the filtration module and prevented the formation of biofilm on the surface of the membrane. Such distinctive antimicrobial properties of the composite membrane is attributed to the proper dispersion of silver nanoparticles on the external surface of the membrane, leading to direct contact with bacterium cells.

  18. Final Report - Energy Reduction and Advanced Water Removal via Membrane Solvent Extraction Technology

    SciTech Connect

    Reed, John; Fanselow, Dan; Abbas, Charles; Sammons, Rhea; Kinchin, Christopher

    2014-08-06

    3M and Archer Daniels Midland (ADM) collaborated with the U.S. Department of Energy (DOE) to develop and demonstrate a novel membrane solvent extraction (MSE) process that can substantially reduce energy and water consumption in ethanol production, and accelerate the fermentation process. A cross-flow membrane module was developed, using porous membrane manufactured by 3M. A pilot process was developed that integrates fermentation, MSE and vacuum distillation. Extended experiments of 48-72 hours each were conducted to develop the process, verify its performance and begin establishing commercial viability.

  19. High lift wake investigation

    NASA Technical Reports Server (NTRS)

    Sullivan, J. P.; Schneider, S. P.; Hoffenberg, R.

    1996-01-01

    The behavior of wakes in adverse pressure gradients is critical to the performance of high-lift systems for transport aircraft. Wake deceleration is known to lead to sudden thickening and the onset of reversed flow; this 'wake bursting' phenomenon can occur while surface flows remain attached. Although known to be important for high-lift systems, few studies of such decelerated wakes exist. In this study, the wake of a flat plate has been subjected to an adverse pressure gradient in a two-dimensional diffuser, whose panels were forced to remain attached by use of slot blowing. Pitot probe surveys, L.D.V. measurements, and flow visualization have been used to investigate the physics of this decelerated wake, through the onset of reversed flow.

  20. Tracking inorganic foulants irreversibly accumulated on low-pressure membranes for treating surface water.

    PubMed

    Yamamura, Hiroshi; Kimura, Katsuki; Higuchi, Kumiko; Watanabe, Yoshimasa; Ding, Qing; Hafuka, Akira

    2015-12-15

    While low-pressure membrane filtration processes (i.e., microfiltration and ultrafiltration) can offer precise filtration than sand filtration, they pose the problem of reduced efficiency due to membrane fouling. Although many studies have examined membrane fouling by organic substances, there is still not enough data available concerning membrane fouling by inorganic substances. The present research investigated changes in the amounts of inorganic components deposited on the surface of membrane filters over time using membrane specimens sampled thirteen times at arbitrary time intervals during pilot testing in order to determine the mechanism by which irreversible fouling by inorganic substances progresses. The experiments showed that the inorganic components that primarily contribute to irreversible fouling vary as filtration continues. It was discovered that, in the initial stage of operation, the main membrane-fouling substance was iron, whereas the primary membrane-fouling substances when operation finished were manganese, calcium, and silica. The amount of iron accumulated on the membrane increased up to the thirtieth day of operation, after which it reached a steady state. After the accumulation of iron became static, subsequent accumulation of manganese was observed. The fact that the removal rates of these inorganic components also increased gradually shows that the size of the exclusion pores of the membrane filter narrows as operation continues. Studying particle size distributions of inorganic components contained in source water revealed that while many iron particles are approximately the same size as membrane pores, the fraction of manganese particles slightly smaller than the pores in diameter was large. From these results, it is surmised that iron particles approximately the same size as the pores block them soon after the start of operation, and as the membrane pores narrow with the development of fouling, they become further blocked by manganese

  1. Lifting liquid from boreholes

    SciTech Connect

    Reese, T.E.

    1983-05-17

    A device for lifting liquid from boreholes comprises a pump which is located downhole in the region of a production formation and which consists of a fluid-actuated, double-action piston. The pump is connected by fluid pressure lines to a source of fluid pressure disposed above ground and a switching valve is connected to provide fluid pressure to alternate sides of the piston to effect reciprocation thereof.

  2. Enhanced Rescue Lift Capability

    NASA Technical Reports Server (NTRS)

    Young, Larry A.

    2007-01-01

    The evolving and ever-increasing demands of emergency response and disaster relief support provided by rotorcraft dictate, among other things, the development of enhanced rescue lift capability for these platforms. This preliminary analysis is first-order in nature but provides considerable insight into some of the challenges inherent in trying to effect rescue using a unique form of robotic rescue device deployed and operated from rotary-wing aerial platforms.

  3. Transport Modeling of Membrane Extraction of Chlorinated Hydrocarbon from Water for Ion Mobility Spectrometry

    SciTech Connect

    Zhang, Wei; Du, Yongzhai; Feng, Zhili; Xu, Jun

    2010-01-01

    Membrane-extraction Ion Mobility Spectrometry (ME-IMS) is a feasible technique for the continuous monitoring of chlorinated hydrocarbons in water. This work studies theoretically the time-dependent characteristics of sampling and detection of trichloroethylene (TCE). The sampling is configured so that aqueous contaminants permeate through a hollow polydimethylsiloxane (PDMS) membrane and are carried away by a transport gas flowing through the membrane tube into IMS analyzer. The theoretical study is based on a two-dimensional transient fluid flow and mass transport model. The model describes the TCE mixing in the water, permeation through the membrane layer, and convective diffusion in the air flow inside membrane tube. The effect of various transport gas flow rates on temporal profiles of IMS signal intensity is investigated. The results show that fast time response and high transport yield can be achieved for ME-IMS by controlling the flow rate in the extraction membrane tube. These modeled time-response profiles are important for determining duty cycles of field-deployable sensors for monitoring chlorinated hydrocarbons in water.

  4. The effect of coupling coagulation and flocculation with membrane filtration in water treatment: a review.

    PubMed

    Leiknes, TorOve

    2009-01-01

    Water supply and sanitation demands are foreseen to face enormous challenges over the coming decades to meet the fast growing needs in a global perspective. Significant growth in the industry is predicted and membrane separation technologies have been identified as one of the possible solutions to meet future demands. Application and implementation of membrane technology is expected both in production of potable water as well as in treatment of wastewater. In potable water production membranes are substituting conventional separation technologies due to the superior performance, potential for less chemical use and sludge production, as well as the potential to fulfill hygienic barrier requirements. Membrane bio-reactor (MBR) technology is probably the membrane process which has had most success and has the best prospects for the future in wastewater treatment. Trends and developments indicate that this technology is becoming accepted and is rapidly becoming the best available technology for many wastewater treatment applications. A major drawback of MBR systems is membrane fouling. Studies have shown that fouling mitigation in MBR systems can potentially be done by coupling coagulation and flocculation to the process.

  5. Hydrogen production by water dissociation using ceramic membranes. Annual report for FY 2007.

    SciTech Connect

    Balachandran, U.; Chen, L.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Park, C. Y.; Picciolo, J. J.; Song, S. J.; Energy Systems

    2008-03-04

    The objective of this project is to develop dense ceramic membranes that, without using an external power supply or circuitry, can produce hydrogen via coal/coal gas-assisted water dissociation. This project grew out of an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions [1]. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen to be produced by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting [1, 2]. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen by means of OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.

  6. Powered-lift aircraft technology

    NASA Technical Reports Server (NTRS)

    Deckert, W. H.; Franklin, J. A.

    1989-01-01

    Powered lift aircraft have the ability to vary the magnitude and direction of the force produced by the propulsion system so as to control the overall lift and streamwise force components of the aircraft, with the objective of enabling the aircraft to operate from minimum sized terminal sites. Power lift technology has contributed to the development of the jet lift Harrier and to the forth coming operational V-22 Tilt Rotor and the C-17 military transport. This technology will soon be expanded to include supersonic fighters with short takeoff and vertical landing capability, and will continue to be used for the development of short- and vertical-takeoff and landing transport. An overview of this field of aeronautical technology is provided for several types of powered lift aircraft. It focuses on the description of various powered lift concepts and their operational capability. Aspects of aerodynamics and flight controls pertinent to powered lift are also discussed.

  7. 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 (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.

  8. 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

  9. Structural and functional properties of hydration and confined water in membrane interfaces.

    PubMed

    Disalvo, E A; Lairion, F; Martini, F; Tymczyszyn, E; Frías, M; Almaleck, H; Gordillo, G J

    2008-12-01

    The scope of the present review focuses on the interfacial properties of cell membranes that may establish a link between the membrane and the cytosolic components. We present evidences that the current view of the membrane as a barrier of permeability that contains an aqueous solution of macromolecules may be replaced by one in which the membrane plays a structural and functional role. Although this idea has been previously suggested, the present is the first systematic work that puts into relevance the relation water-membrane in terms of thermodynamic and structural properties of the interphases that cannot be ignored in the understanding of cell function. To pursue this aim, we introduce a new definition of interphase, in which the water is organized in different levels on the surface with different binding energies. Altogether determines the surface free energy necessary for the structural response to changes in the surrounding media. The physical chemical properties of this region are interpreted in terms of hydration water and confined water, which explain the interaction with proteins and could affect the modulation of enzyme activity. Information provided by several methodologies indicates that the organization of the hydration states is not restricted to the membrane plane albeit to a region extending into the cytoplasm, in which polar head groups play a relevant role. In addition, dynamic properties studied by cyclic voltammetry allow one to deduce the energetics of the conformational changes of the lipid head group in relation to the head-head interactions due to the presence of carbonyls and phosphates at the interphase. These groups are, apparently, surrounded by more than one layer of water molecules: a tightly bound shell, that mostly contributes to the dipole potential, and a second one that may be displaced by proteins and osmotic stress. Hydration water around carbonyl and phosphate groups may change by the presence of polyhydroxylated compounds

  10. In situ polymerized superhydrophobic and superoleophilic nanofibrous membranes for gravity driven oil-water separation

    NASA Astrophysics Data System (ADS)

    Tang, Xiaomin; Si, Yang; Ge, Jianlong; Ding, Bin; Liu, Lifang; Zheng, Gang; Luo, Wenjing; Yu, Jianyong

    2013-11-01

    Creating an efficient, cost-effective method that can provide simple, practical and high-throughput separation of oil-water mixtures has proved extremely challenging. This work responds to these challenges by designing, fabricating and evaluating a novel fluorinated polybenzoxazine (F-PBZ) modified nanofibrous membrane optimized to achieve gravity driven oil-water separation. The membrane design is then realized by a facile combination of electrospun poly(m-phenylene isophthalamide) (PMIA) nanofibers and an in situ polymerized F-PBZ functional layer incorporating SiO2 nanoparticles (SiO2 NPs). By employing the F-PBZ/SiO2 NP modification, the pristine hydrophilic PMIA nanofibrous membranes are endowed with promising superhydrophobicity with a water contact angle of 161° and superoleophilicity with an oil contact angle of 0°. This new membrane shows high thermal stability (350 °C) and good repellency to hot water (80 °C), and achieves an excellent mechanical strength of 40.8 MPa. Furthermore, the as-prepared membranes exhibited fast and efficient separation of oil-water mixtures by a solely gravity driven process, which makes them good candidates for industrial oil-polluted water treatments and oil spill cleanup, and also provided new insights into the design and development of functional nanofibrous membranes through F-PBZ modification.Creating an efficient, cost-effective method that can provide simple, practical and high-throughput separation of oil-water mixtures has proved extremely challenging. This work responds to these challenges by designing, fabricating and evaluating a novel fluorinated polybenzoxazine (F-PBZ) modified nanofibrous membrane optimized to achieve gravity driven oil-water separation. The membrane design is then realized by a facile combination of electrospun poly(m-phenylene isophthalamide) (PMIA) nanofibers and an in situ polymerized F-PBZ functional layer incorporating SiO2 nanoparticles (SiO2 NPs). By employing the F-PBZ/SiO2 NP

  11. A review of water flooding issues in the proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Li, Hui; Tang, Yanghua; Wang, Zhenwei; Shi, Zheng; Wu, Shaohong; Song, Datong; Zhang, Jianlu; Fatih, Khalid; Zhang, Jiujun; Wang, Haijiang; Liu, Zhongsheng; Abouatallah, Rami; Mazza, Antonio

    We have reviewed more than 100 references that are related to water management in proton exchange membrane (PEM) fuel cells, with a particular focus on the issue of water flooding, its diagnosis and mitigation. It was found that extensive work has been carried out on the issues of flooding during the last two decades, including prediction through numerical modeling, detection by experimental measurements, and mitigation through the design of cell components and manipulating the operating conditions. Two classes of strategies to mitigate flooding have been developed. The first is based on system design and engineering, which is often accompanied by significant parasitic power loss. The second class is based on membrane electrode assembly (MEA) design and engineering, and involves modifying the material and structural properties of the gas diffusion layer (GDL), cathode catalyst layer (CCL) and membrane to function in the presence of liquid water. In this review, several insightful directions are also suggested for future investigation.

  12. Development of a preprototype thermoelectric integrated membrane evaporation subsystem for water recovery

    NASA Technical Reports Server (NTRS)

    Winkler, H. E.; Roebelen, G. J., Jr.

    1980-01-01

    A three-man urine water recovery preprototype subsystem using a new concept to provide efficient potable water recovery from waste fluids on extended duration space flights has been designed, fabricated, and tested. Low power, compactness, and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber polysulfone membrane evaporator with a thermoelectric heat pump. Application and integration of these key elements have solved problems inherent in previous reclamation subsystem designs. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than a waste liquid recirculation pump and a product water withdrawal pump. Tubular membranes provide structural integrity, improving on previous flat sheet membrane designs. A thermoelectric heat pump provides latent energy recovery.

  13. Water populations in restricted environments of lipid membrane interphases.

    PubMed

    Alarcón, Laureano M; de Los Angeles Frías, M; Morini, Marcela A; Belén Sierra, M; Appignanesi, Gustavo A; Anibal Disalvo, E

    2016-10-01

    We employ molecular dynamics simulations to study the hydration properties of Dipalmitoylphosphatidylcholine (DPPC) bilayers, both in the gel and the liquid crystalline states. We show that while the tight hydration centers (PO and CO moieties) are significantly hydrated in both phases, the gel-fluid transition involves significant changes at the second hydration shell, particularly at the buried region between the hydrocarbon tails. Thus, while almost no buried water population exists in the gel state below the carbonyls, this hydrophobic region becomes partially water accesible in the liquid crystalline state. We shall also show that such water molecules present a lower H-bond coordination as compared to the molecules at the primary hydration shell. This means that, while the latter are arranged in relatively compact nanoclusters (as already proposed), the buried water molecules tend to organize themselves in less compact structures, typically strings or branched strings, with a scarce population of isolated molecules. This behavior is similar to that observed in other hydration contexts, like water penetrating carbon nanotubes or model hydrophobic channels or pores, and reflects the reluctance of water to sacrifice HB coordination.

  14. Highly permeable polymeric membranes based on the incorporation of the functional water channel protein Aquaporin Z

    PubMed Central

    Kumar, Manish; Grzelakowski, Mariusz; Zilles, Julie; Clark, Mark; Meier, Wolfgang

    2007-01-01

    The permeability and solute transport characteristics of amphiphilic triblock-polymer vesicles containing the bacterial water-channel protein Aquaporin Z (AqpZ) were investigated. The vesicles were made of a block copolymer with symmetric poly-(2-methyloxazoline)-poly-(dimethylsiloxane)-poly-(2-methyloxazoline) (PMOXA15-PDMS110-PMOXA15) repeat units. Light-scattering measurements on pure polymer vesicles subject to an outwardly directed salt gradient in a stopped-flow apparatus indicated that the polymer vesicles were highly impermeable. However, a large enhancement in water productivity (permeability per unit driving force) of up to ≈800 times that of pure polymer was observed when AqpZ was incorporated. The activation energy (Ea) of water transport for the protein-polymer vesicles (3.4 kcal/mol) corresponded to that reported for water-channel-mediated water transport in lipid membranes. The solute reflection coefficients of glucose, glycerol, salt, and urea were also calculated, and indicated that these solutes are completely rejected. The productivity of AqpZ-incorporated polymer membranes was at least an order of magnitude larger than values for existing salt-rejecting polymeric membranes. The approach followed here may lead to more productive and sustainable water treatment membranes, whereas the variable levels of permeability obtained with different concentrations of AqpZ may provide a key property for drug delivery applications. PMID:18077364

  15. Polymer Electrolyte Fuel Cells Membrane Hydration by Direct Liquid Water Contact

    SciTech Connect

    Wilson, M.S.; Zawodzinski, C.; Gottesfeld, S.

    1998-11-01

    An effective means of providing direct liquid hydration of the membrane tends to improve performance particularly of cells with thicker membranes or at elevated temperatures. Supplying the water to the membrane from the anode flow-field through the anode backing via wicks would appear to have advantages over delivering the water through the thickness of the membrane with regards to the uniformity and stability of the supply and the use of off-the-shelf membranes or MEAs. In addition to improving cell performance, an important contribution of direct liquid hydration approaches may be that the overall fuel cell system becomes simpler and more effective. The next steps in the evolution of this approach are a demonstration of the effectiveness of this technique with larger active area cells as well as the implementation of an internal flow-field water reservoir (to eliminate the injection method). Scale-up to larger cell sizes and the use of separate water channels within the anode flow-field is described.

  16. Determination of fuel ethers in water by membrane extraction ion mobility spectrometry.

    PubMed

    Holopainen, Sanna; Nousiainen, Marjaana; Sillanpää, Mika

    2013-03-15

    Fuel oxygenates are environmentally detrimental compounds due to their rapid migration to groundwater. Fuel oxygenates have been reported to cause taste and odour problems in drinking water, and they also have long-term health effects. Feasible analytical methods are required to observe the presence of fuel oxygenates in drinking and natural water. The authors studied ion mobility spectrometry (IMS) to determinate isomeric fuel ether oxygenates; ethyl tert-butyl ether (ETBE), diisopropyl ether (DIPE), and tert-amyl methyl ether (TAME), separated from aqueous matrices with a pervaporation membrane module. Methyl tert-butyl ether (MTBE) was also membrane extracted and detected with IMS. The authors demonstrated that fuel ethers (MTBE, ETBE, DIPE, and TAME) can be quantified at μg/L level with membrane extraction IMS. A membrane extraction module coupled to IMS is a time and cost effective analysis method because sampling can be performed in a single procedure and from different natural water matrices within a few minutes. Consequently, IMS combined with membrane extraction is suitable not only for waterworks and other online applications but also in the field monitoring the quality of drinking and natural water.

  17. 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).

  18. Diffusion of water in nano-porous polyamide membranes: Quasielastic neutron scattering study

    NASA Astrophysics Data System (ADS)

    Sharma, V. K.; Mitra, S.; Singh, P.; Jurányi, F.; Mukhopadhyay, R.

    2010-10-01

    Dynamics of water sorbed in a reverse osmosis polyamide membrane (ROPM) as studied by quasielastic neutron scattering (QENS) is reported here. The trimesoylchloride-m-phenylene diamine based ROPM is synthesized by interfacial polymerization technique. QENS data indicates that translational motion of water confined in ROPM gets modified compared to bulk water whereas rotational motion remains unaltered. Translational motion of water in ROPM is found to follow random jump diffusion with lower diffusivity compared to bulk water. Translational diffusivity does not show the Arrhenius behaviour.

  19. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    The efforts on the synthesis of polymer anion redox membranes were mainly concentrated in two areas, membrane development and membrane fabrication. Membrane development covered the preparation and evaluation of experimental membranes systems with improved resistance stability and/or lower permeability. Membrane fabrication covered the laboratory scale production of prime candidate membranes in quantities of up to two hundred and sizes up to 18 inches x 18 inches (46 cm x 46 cm). These small (10 in x 11 in) and medium sized membranes were mainly for assembly into multicell units. Improvements in processing procedures and techniques for preparing such membrane sets lifted yields to over 90 percent.

  20. Biologically Inspired Photocatalytically Active Membranes for Water Treatment

    NASA Astrophysics Data System (ADS)

    Kinsinger, Nichola M.

    There is an alarming increase of a variety of new chemicals that are now being discharged into the wastewater system causing increased concern for public health and safety because many are not removed by typical wastewater treatment practices. Titanium Dioxide (TiO2) is a heterogeneous photocatalytic material that rapidly and completely mineralizing organics without harmful byproducts. TiO2 is synthesized by various methods, which lack the necessary control of crystal size, phase, and morphological features that yield optimized semiconductor materials. Mineralizing organisms demonstrate how nature can produce elegant structures at room temperature through controlled organic-mineral interactions. Here, we utilize biologically-inspired scaffolds to template the nucleation and growth of inorganic materials such as TiO2, which aid in controlling the size and phase of these particles and ultimately, their properties. Nanosized rutile and anatase particles were synthesized under solution conditions at relatively low temperatures and mild pH conditions. The effects of reaction conditions on phase and grain size were investigated and discussed from coordination chemistry and coarsening mechanisms. Photocatalytic characterization of TiO2 phase mixtures was performed to investigate their synergistic effect. The suspension conditions of these catalytic nanomaterials were modulated to optimize the degradation rate of organic analytes. Through the addition of an organic scaffold during the synthesis reaction, a mechanically robust (elastic) composite material containing TiO2 nanoparticles was produced. This composite was subsequently heat-treated to produce a porous, high surface area TiO2 nanoparticulate membrane. Processing conditions were investigated to characterize the growth and phase transformation of TiO2, which ultimately impacts photocatalytic performance. These bulk porous TiO2 structures can be fabricated and tailored to act as stand-alone photocatalytic membranes

  1. Carbon nanotube membranes with ultrahigh specific adsorption capacity for water desalination and purification.

    PubMed

    Yang, Hui Ying; Han, Zhao Jun; Yu, Siu Fung; Pey, Kin Leong; Ostrikov, Kostya; Karnik, Rohit

    2013-01-01

    Development of technologies for water desalination and purification is critical to meet the global challenges of insufficient water supply and inadequate sanitation, especially for point-of-use applications. Conventional desalination methods are energy and operationally intensive, whereas adsorption-based techniques are simple and easy to use for point-of-use water purification, yet their capacity to remove salts is limited. Here we report that plasma-modified ultralong carbon nanotubes exhibit ultrahigh specific adsorption capacity for salt (exceeding 400% by weight) that is two orders of magnitude higher than that found in the current state-of-the-art activated carbon-based water treatment systems. We exploit this adsorption capacity in ultralong carbon nanotube-based membranes that can remove salt, as well as organic and metal contaminants. These ultralong carbon nanotube-based membranes may lead to next-generation rechargeable, point-of-use potable water purification appliances with superior desalination, disinfection and filtration properties.

  2. Fast Water Thermo-pumping Flow Across Nanotube Membranes for Desalination.

    PubMed

    Zhao, Kuiwen; Wu, Huiying

    2015-06-10

    Development of high-efficiency and low-cost seawater desalination technologies is critical to meet global water crisis. Here we report a fast water pumping method in which the water molecules in seawater are continuously pumped across nanotube membranes driven by a small temperature difference, opening the possibility of high-throughput small-scale desalination devices driven by low-grade thermal energy. Using molecular dynamics simulations, we show that an equivalent driving pressure of 5.3 MPa is achieved with a temperature difference of only 15 K. The remarkable water pumping ability is attributed to the asymmetric thermal fluctuation of water molecules. With this method, a 10 cm(2) nanotube membrane with 1.5 × 10(13) pores per cm(2) will produce freshwater with a flow rate of 7.77 L/h under a small temperature difference of 15 K.

  3. Water permeability of polyethylene terephthalate track membranes modified in plasma of dimethylaniline

    NASA Astrophysics Data System (ADS)

    Kravets, Lyubov; Dmitriev, Serguei; Gilman, Alla; Drachev, Alexander

    2004-09-01

    The surface properties and hydrodynamic characteristics of composite membranes consisting of a porous substrate, on which a polymer layer from a direct current discharge in a mixture of air and vapours of dimethylaniline was deposited, have been investigated. As a substrate, we used poly(ethylene) terephthalate track membrane (PET TM) of the thickness of 10 μ m and the effective pore diameter of 0.215 μ m (pore density is 2\\cdot 10^8 cm-2). The performed researches show that when treating the membranes in plasma, two competing processes are observed: deposition of the polymer layer on a membrane surface, that testifies increase of the mass of sample, and etching of a polymeric matrix which causes growth of effective pore diameter. The last process is stipulated by presence of oxygen in the gas mixture. Decreasing the degree of overweight of the sample at increasing the treatment time leads us to a supposition that a dominating process in this case becomes the process of gas-discharge etching. In all cases, if treating PET TM, a drop of the water contact angle occurs, i.e. hydrophilization of the membrane surface takes place that is connected first of all with a grafting of polymer layer containing polar functional groups. The research in the hydrodynamic characteristics of the initial PET TM and the membranes modified in plasma at neutral and subacid pH value of filtrate leads to a linear dependence of their permeability upon the quantity of applied pressure. It is connected with a viscous character of the flow, that is, when the diameter of the pores of the membrane is much more than the size of the water molecules. This fact shows that the macromolecules of the deposited polymer layer in this case have a compact conformation, which does not hinder the water molecules infiltration. At a lower pH value of the filtrate, the picture cardinally changes. For modified in plasma membranes a diversion from the linear relation is observed. This means that in this case

  4. Virus disinfection in water by biogenic silver immobilized in polyvinylidene fluoride membranes

    SciTech Connect

    Gusseme, B.D.; Fitts, J.; Hennebel, T.; Christiaens, E.; Saveyn, H.; Verbeken, K.; Boon, N.; Verstraete, W.

    2011-03-01

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag{sup 0}) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag{sup 0} particles, preventing aggregation during encapsulation. In this study, bio-Ag{sup 0} was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag{sup 0} and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag{sup +} from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag{sub powder}{sup 0} m{sup -2} in a submerged plate membrane reactor operated at a flux of 3.1 L m{sup -2} h{sup -1}. Upon startup, the silver concentration in the effluent initially increased to 271 {micro}g L{sup -1} but after filtration of 31 L m{sup -2}, the concentration approached the drinking water limit (= 100 {micro}g L{sup -1}). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m{sup -2} h{sup -1}, showing the potential of this membrane technology for water disinfection on small scale. In biogenic silver, silver nanoparticles are attached to a bacterial carrier matrix. Bio-Ag{sup 0} was successfully immobilized in PVDF membranes using immersion-precipitation. The antiviral activity of this material was demonstrated in a plate membrane reactor. The antimicrobial mechanism was most probably related to the slow release of Ag{sup +} ions. The membranes can be applied for treatment of limited volumes of contaminated water.

  5. Improving the Performance and Antifouling Properties of Thin-Film Composite Membranes for Water Separation Technologies

    NASA Astrophysics Data System (ADS)

    Tiraferri, Alberto

    Membrane-based water separation processes utilize semi-permeable membranes to retain dissolved solids and contaminants. Deployment of these technologies for desalination and wastewater reuse has the potential to sustainably increase the supply of potable, agricultural, and industrial water. Despite considerable development of semi-permeable membranes in the last decades, several design obstacles hampering their progress have yet to be overcome. Specifically, major membrane improvements are currently sought with respect to their performance and productivity, as well as their resistance to fouling. This dissertation research aims at the advancement of semi-permeable membranes by rational optimization of their design to: (i) understand and improve their transport properties and (ii) reduce fouling by organic molecules and delay biofouling by microorganisms. In particular, thin-film composite polyamide membranes for both reverse osmosis and forward osmosis processes are the main target of the investigation. The structural and physicochemical properties of thin-film composite membranes are both characterized and tailored through implementation of original techniques and novel functionalization protocols. The membrane structure and morphology are rationally modified to enhance the mass transport within the support layer. The influence of fabrication conditions on support layer formation and on its final structure is elucidated. The intricate interrelationship among the performance of the different layers of the composite membrane is highlighted and a new protocol is developed to characterize the transport properties of membranes deployed in forward osmosis processes. Novel approaches to impart targeted properties to the active surface of thin-film composite membranes are also proposed. The functionalization is achieved by exploiting the inherent moieties of the polyamide layer to irreversibly bind nanomaterials with desired properties. An experimental method to determine

  6. Biofouling of Water Treatment Membranes: A Review of the Underlying Causes, Monitoring Techniques and Control Measures

    PubMed Central

    Nguyen, Thang; Roddick, Felicity A.; Fan, Linhua

    2012-01-01

    Biofouling is a critical issue in membrane water and wastewater treatment as it greatly compromises the efficiency of the treatment processes. It is difficult to control, and significant economic resources have been dedicated to the development of effective biofouling monitoring and control strategies. This paper highlights the underlying causes of membrane biofouling and provides a review on recent developments of potential monitoring and control methods in water and wastewater treatment with the aim of identifying the remaining issues and challenges in this area. PMID:24958430

  7. Assessment of a membrane drinking water filter in an emergency setting.

    PubMed

    Ensink, Jeroen H J; Bastable, Andy; Cairncross, Sandy

    2015-06-01

    The performance and acceptability of the Nerox(TM) membrane drinking water filter were evaluated among an internally displaced population in Pakistan. The membrane filter and a control ceramic candle filter were distributed to over 3,000 households. Following a 6-month period, 230 households were visited and filter performance and use were assessed. Only 6% of the visited households still had a functioning filter, and the removal performance ranged from 80 to 93%. High turbidity in source water (irrigation canals), together with high temperatures and large family size were likely to have contributed to poor performance and uptake of the filters.

  8. Zwitterion functionalized carbon nanotube/polyamide nanocomposite membranes for water desalination.

    PubMed

    Chan, Wai-Fong; Chen, Hang-yan; Surapathi, Anil; Taylor, Michael G; Shao, Xiaohong; Marand, Eva; Johnson, J Karl

    2013-06-25

    We have shown from both simulations and experiments that zwitterion functionalized carbon nanotubes (CNTs) can be used to construct highly efficient desalination membranes. Our simulations predicted that zwitterion functional groups at the ends of CNTs allow a high flux of water, while rejecting essentially all ions. We have synthesized zwitterion functionalized CNT/polyamide nanocomposite membranes with varying loadings of CNTs and assessed these membranes for water desalination. The CNTs within the polyamide layer were partially aligned through a high-vacuum filtration step during membrane synthesis. Addition of zwitterion functionalized CNTs into a polyamide membrane increased both the flux of water and the salt rejection ratio. The flux of water was found to increase by more than a factor of 4, from 6.8 to 28.7 GFD (gallons per square foot per day), as the fraction of CNTs was increased from 0 to 20 wt %. Importantly, the ion rejection ratio increased slightly from 97.6% to 98.6%. Thus, the nanotubes imparted an additional transport mechanism to the polyamide membrane, having higher flow rate and the same or slightly better selectivity. Simulations show that when two zwitterions are attached to each end of CNTs having diameters of about 15 Å, the ion rejection ratio is essentially 100%. In contrast, the rejection ratio for nonfunctionalized CNTs is about 0%, and roughly 20% for CNTs having five carboxylic acid groups per end. The increase in ion rejection for the zwitterion functionalized CNTs is due to a combination of steric hindrance from the functional groups partially blocking the tube ends and electrostatic repulsion between functional groups and ions, with steric effects dominating. Theoretical predictions indicate that an ideal CNT/polymer membrane having a loading of 20 wt % CNTs would have a maximum flux of about 20000 GFD at the conditions of our experiments.

  9. Virus Disinfection in Water by Biogenic Silver Immobilized in Polyvinylidene Fluoride Membranes

    SciTech Connect

    B De Gusseme; T Hennebel; E Christiaens; H Saveyn; K Verbeken; J Fitts; N Boon; W Vertraete

    2011-12-31

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag{sup 0}) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag{sup 0} particles, preventing aggregation during encapsulation. In this study, bio-Ag{sup 0} was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag{sup 0} and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag{sup +} from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag{sup 0}{sub powder} m{sup -2} in a submerged plate membrane reactor operated at a flux of 3.1 L m{sup -2} h{sup -1}. Upon startup, the silver concentration in the effluent initially increased to 271 {mu}g L{sub -1} but after filtration of 31 L m{sup -2}, the concentration approached the drinking water limit (= 100 {mu}g L{sup -1}). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m{sup -2} h{sup -1}, showing the potential of this membrane technology for water disinfection on small scale.

  10. Probing membrane protein structure using water polarization transfer solid-state NMR

    NASA Astrophysics Data System (ADS)

    Williams, Jonathan K.; Hong, Mei

    2014-10-01

    Water plays an essential role in the structure and function of proteins, lipid membranes and other biological macromolecules. Solid-state NMR heteronuclear-detected 1H polarization transfer from water to biomolecules is a versatile approach for studying water-protein, water-membrane, and water-carbohydrate interactions in biology. We review radiofrequency pulse sequences for measuring water polarization transfer to biomolecules, the mechanisms of polarization transfer, and the application of this method to various biological systems. Three polarization transfer mechanisms, chemical exchange, spin diffusion and NOE, manifest themselves at different temperatures, magic-angle-spinning frequencies, and pulse irradiations. Chemical exchange is ubiquitous in all systems examined so far, and spin diffusion plays the key role in polarization transfer within the macromolecule. Tightly bound water molecules with long residence times are rare in proteins at ambient temperature. The water polarization-transfer technique has been used to study the hydration of microcrystalline proteins, lipid membranes, and plant cell wall polysaccharides, and to derive atomic-resolution details of the kinetics and mechanism of ion conduction in channels and pumps. Using this approach, we have measured the water polarization transfer to the transmembrane domain of the influenza M2 protein to obtain information on the structure of this tetrameric proton channel. At short mixing times, the polarization transfer rates are site-specific and depend on the pH, labile protons, sidechain conformation, as well as the radial position of the residues in this four-helix bundle. Despite the multiple dependences, the initial transfer rates reflect the periodic nature of the residue positions from the water-filled pore, thus this technique provides a way of gleaning secondary structure information, helix tilt angle, and the oligomeric structure of membrane proteins.

  11. Probing membrane protein structure using water polarization transfer solid-state NMR.

    PubMed

    Williams, Jonathan K; Hong, Mei

    2014-10-01

    Water plays an essential role in the structure and function of proteins, lipid membranes and other biological macromolecules. Solid-state NMR heteronuclear-detected (1)H polarization transfer from water to biomolecules is a versatile approach for studying water-protein, water-membrane, and water-carbohydrate interactions in biology. We review radiofrequency pulse sequences for measuring water polarization transfer to biomolecules, the mechanisms of polarization transfer, and the application of this method to various biological systems. Three polarization transfer mechanisms, chemical exchange, spin diffusion and NOE, manifest themselves at different temperatures, magic-angle-spinning frequencies, and pulse irradiations. Chemical exchange is ubiquitous in all systems examined so far, and spin diffusion plays the key role in polarization transfer within the macromolecule. Tightly bound water molecules with long residence times are rare in proteins at ambient temperature. The water polarization-transfer technique has been used to study the hydration of microcrystalline proteins, lipid membranes, and plant cell wall polysaccharides, and to derive atomic-resolution details of the kinetics and mechanism of ion conduction in channels and pumps. Using this approach, we have measured the water polarization transfer to the transmembrane domain of the influenza M2 protein to obtain information on the structure of this tetrameric proton channel. At short mixing times, the polarization transfer rates are site-specific and depend on the pH, labile protons, sidechain conformation, as well as the radial position of the residues in this four-helix bundle. Despite the multiple dependences, the initial transfer rates reflect the periodic nature of the residue positions from the water-filled pore, thus this technique provides a way of gleaning secondary structure information, helix tilt angle, and the oligomeric structure of membrane proteins.

  12. Removal of bromate from drinking water using the ion exchange membrane bioreactor concept.

    PubMed

    Matos, Cristina T; Velizarov, Svetlozar; Reis, Maria A M; Crespo, João G

    2008-10-15

    Bromate is a disinfection byproduct with carcinogenic properties that has to be removed from drinking water to concentrations below 10 or 25 microg/L. This work evaluates the applicability of the ion exchange membrane bioreactor (IEMB) concept for the removal of bromate from drinking water, in situations where nitrate is also present in concentrations up to 3 orders of magnitude higher than bromate. The batch results obtained show that the biological reduction of bromate was slow and only occurring after the complete reduction of nitrate. The specific bromate reduction rates varied from 0.027 +/- 0.01 mg BrO3(-)/g(cell dry weight) x h to 0.090 mg BrO3(-)/ g(cell dry weight) x h for the studied concentrations. On the other hand, transport studies, using anion exchange membranes showed that Donnan dialysis could efficiently remove bromate from polluted waters. Therefore, the use of a dense, nonporous membrane in the IEMB system, isolates the water stream from the biological compartment, allowing for the uncoupling of the water production rate from the biological reduction rate. The IEMB system was used for the treatment of a polluted water stream containing 200 microg/L of BrO3(-) and 60 mg/L of NO3(-). The concentrations of both ions in the treated water were reduced below the recommended levels. No bromate accumulation was observed in the biocompartment of the IEMB, suggesting its complete reduction in the biofilm formed on the membrane surface contacting the biocompartment. Therefore, the IEMB has proven to be a technology able to solve specific problems associated with the removal of bromate from water streams, since it efficiently removes bromate from drinking water even in the presence of nitrate, a known competitor of bromate biological reduction, without secondary contamination of the treated water by cells or excess of carbon source.

  13. Preparation of antifouling polyvinylpyrrolidone (PVP 40K) modified polyethersulfone (PES) ultrafiltration (UF) membrane for water purification

    NASA Astrophysics Data System (ADS)

    Vatsha, Banele; Ngila, Jane Catherine; Moutloali, Richard M.

    This study reports the fabrication of polyethersulfone (PES) membrane using the phase inversion method in the presence of polyvinylpyrrolidone (PVP, 40K) as pore-forming agent. The membranes were made from two PES concentration types, i.e. 16 and 18 wt.%. The effect of high molecular weight PVP concentration (2-10%) was examined in order to obtain a membrane with good performance, i.e. high water flux and reasonable Bovine Serum Albumin (BSA, protein model solution) rejection. The optimised membranes were characterised by ATR-FTIR, AFM, SEM, contact angle and dead-end membrane filtration tests. It was found that PVP moieties have positive influence in the prepared PES membranes. SEM surface and cross-sectional images were used to observed morphological changes as PVP content was varied. The pore sizes increased with PVP content for membranes prepared from 16 wt.% PES polymer, whereas at the higher PVP content in 18 wt.% PES membrane, pore sizes tend to decrease or completely disappear. The CA decreased gradually for the 16 wt.% PES with increasing PVP content whereas in the 18 wt.% PES the CA decreased initially before tapering off or increasing slightly. The rejection of BSA solution by both neat PES and PVP-containing PES membrane was above 85%. AFM surface topography exhibited increase in roughness value with PVP content. FTIR/ATR spectra corroborated the functional composition of neat PES and PVP molecule dispersed on PES membrane backbone. The results attained confirmed the potential industrial application of PVP molecule to minimise fouling tendencies.

  14. SiC-BASED HYDROGEN SELECTIVE MEMBRANES FOR WATER-GAS-SHIFT REACTION

    SciTech Connect

    Paul K.T. Liu

    2001-10-16

    This technical report summarizes our activities conducted in Yr II. In Yr I we successfully demonstrated the feasibility of preparing the hydrogen selective SiC membrane with a chemical vapor deposition (CVD) technique. In addition, a SiC macroporous membrane was fabricated as a substrate candidate for the proposed SiC membrane. In Yr II we have focused on the development of a microporous SiC membrane as an intermediate layer between the substrate and the final membrane layer prepared from CVD. Powders and supported thin silicon carbide films (membranes) were prepared by a sol-gel technique using silica sol precursors as the source of silicon, and phenolic resin as the source of carbon. The powders and films were prepared by the carbothermal reduction reaction between the silica and the carbon source. The XRD analysis indicates that the powders and films consist of SiC, while the surface area measurement indicates that they contain micropores. SEM and AFM studies of the same films also validate this observation. The powders and membranes were also stable under different corrosive and harsh environments. The effects of these different treatments on the internal surface area, pore size distribution, and transport properties, were studied for both the powders and the membranes using the aforementioned techniques and XPS. Finally the SiC membrane materials are shown to have satisfactory hydrothermal stability for the proposed application. In Yr III, we will focus on the demonstration of the potential benefit using the SiC membrane developed from Yr I and II for the water-gas-shift (WGS) reaction.

  15. Mechanics and molecular filtration performance of graphyne nanoweb membranes for selective water purification

    NASA Astrophysics Data System (ADS)

    Lin, Shangchao; Buehler, Markus J.

    2013-11-01

    Two-dimensional carbon materials such as the 2D nanoweb-like graphyne membrane are promising as molecular sieves for energy and environmental applications. Based on the application of water purification - the removal of contaminants from wastewater and seawater - here we use molecular dynamics (MD) simulations to investigate the interplay between mechanical forces, filtration mechanisms, and overall performance for graphyne membranes with different pore sizes. We carry out biaxial tensile tests and verify the superior mechanical robustness and tolerance of graphyne membranes against possible deformations from the membrane installation process. A possible ultimate stress in excess of 15 GPa and an ultimate strain of 1.2-2.7% are determined. We also demonstrate their excellent filtration performance with barrier-free water permeation and perfect rejection of the representative contaminants considered here, including divalent heavy metal salts (copper sulfate), hydrophobic organic chemicals (benzene and carbon tetrachloride), and inorganic monovalent salts (sodium chloride). We find that graphtriyne, with an effective pore diameter of 3.8 Å, exhibits an optimal purification performance, because the contaminant rejection rate is more sensitive to pore size than water permeability. In addition, we find that the hydrophobic graphyne membranes exhibit higher rejection rates for hydrophilic contaminants compared to the hydrophobic ones. This size exclusion effect is a result of the larger hydrated radii of hydrophilic species due to stronger interactions between them and water molecules. Finally, we find that the maximum deformation of graphtriyne at the ultimate strain before material failure has only a minor impact on its filtration performance. One of the advantages of using graphyne for water purification is that no chemical functionalization or defects need to be introduced, which maintains the structural integrity of the membrane, and possibly, the long-term device

  16. Sensitivity of Hollow Fiber Spacesuit Water Membrane Evaporator Systems to Potable Water Constituents, Contaminants and Air Bubbles

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Trevino, Luis A.; Fritts, Sharon; Tsioulos, Gus

    2008-01-01

    The Spacesuit Water Membrane Evaporator (SWME) is the baseline heat rejection technology selected for development for the Constellation lunar suit. The first SWME prototype, designed, built, and tested at Johnson Space Center in 1999 used a Teflon hydrophobic porous membrane sheet shaped into an annulus to provide cooling to the coolant loop through water evaporation to the vacuum of space. This present study describes the test methodology and planning and compares the test performance of three commercially available hollow fiber materials as alternatives to the sheet membrane prototype for SWME, in particular, a porous hydrophobic polypropylene, and two variants that employ ion exchange through non-porous hydrophilic modified Nafion. Contamination tests will be performed to probe for sensitivities of the candidate SWME elements to ordinary constituents that are expected to be found in the potable water provided by the vehicle, the target feedwater source. Some of the impurities in potable water are volatile, such as the organics, while others, such as the metals and inorganic ions are nonvolatile. The non-volatile constituents will concentrate in the SWME as evaporated water from the loop is replaced by the feedwater. At some point in the SWME mission lifecycle as the concentrations of the non-volatiles increase, the solubility limits of one or more of the constituents may be reached. The resulting presence of precipitate in the coolant water may begin to plug pores and tube channels and affect the SWME performance. Sensitivity to macroparticles, lunar dust simulant, and air bubbles will also be investigated.

  17. Membrane-Extraction Ion Mobility Spectrometry for In-Situ Detection of Chlorinated Hydrocarbons in Water

    SciTech Connect

    Du, Yongzhai; Zhang, Wei; Whitten, William B; Li, Haiyang; Watson, David B; Xu, Jun

    2010-01-01

    Membrane-extraction ion mobility spectrometry (ME-IMS) has been developed for in-situ sampling and analysis of trace chlorinated hydrocarbons in water in a single procedure. The sampling is configured so that aqueous contaminants permeate through a spiral hollow polydimethylsiloxane (PDMS) membrane and are carried away by a vapor flow through the membrane tube. The extracted analyte flows into an atmospheric pressure chemical ionization (APCI) chamber and is analyzed in a home-made IMS analyzer. PDMS membrane is found to effectively extract chlorinated hydrocarbon solvents from liquid phase to vapor. The specialized IMS analyzer has been found to have resolutions of R=33 and 41, respectively, for negative- and positive-modes and is capable of detecting aqueous tetrachloroethylene (PCE) and trichloroethylene (TCE) as low as 80 g/L and 74 g/L in negative ion mode, respectively. The time-dependent characteristics of sampling and detection of TCE are both experimentally and theoretically studied for various concentrations, membrane lengths, and flow rates. These characteristics demonstrate that membrane-extraction IMS is feasible for the continuous monitoring of chlorinated hydrocarbons in water.

  18. A reversible water electrolyser with porous PTFE based OH- conductive membrane as energy storage cells

    NASA Astrophysics Data System (ADS)

    Wu, Xu; Scott, Keith; Xie, Fang; Alford, Neil

    2014-01-01

    An OH- conductive anion exchange membrane was prepared by a pore-filling method with porous polytetrafluoroethylene and a quaternary ammonium polymethacrylate ionomer. The composite membrane exhibited less swelling ratios of thickness and area variation and stronger tensile strength than the pristine polymethacrylate membrane. The ionic conductivity of the composite membrane was not as good as the pristine polymethacrylate ionomer membrane. However, the composite membrane was ultra-thin therefore it leaded to a smaller ionic resistance of the MEA and improved current densities. In fuel cell mode, the peak power densities were respectively 0.114 and 0.163 W cm-2 at 20 and 45 °C. In water electrolyser mode, at a current density of 100 mA cm-2 the cell voltages were about 1.61 V and 1.52 V respectively at 22 °C and 50 °C. In the water electrolyser mode, the degradation rate was only 0.0379 mV h-1 after 120 h at a current density of 100 mA cm-2 at 22 °C.

  19. Water circuit closure with membrane technology in the pulp and paper industry.

    PubMed

    Nuortila-Jokinen, J; Mänttäri, M; Huuhilo, T; Kallioinen, M; Nyström, M

    2004-01-01

    In this study, membrane filtration as an internal purification method, "the kidney", in the pulp and paper industry is discussed. Membrane filtration is economically competitive and a very versatile process. It can be used to remove the enriched organic and/or inorganic loads either partially or totally from, for example, the mechanical pulping and paper making water circuits and it can be applied to various points within the process. With the so-called shear enhanced membrane modules very high fluxes, in ultrafiltration about 400 L/(m2h) and in nanofiltration fluxes almost 200 L/(m2h), have been obtained. Depending on the membrane, suspended solids (microfiltration), polysaccharides, extractives and high molar mass lignous substances (ultrafiltration) and multivalent salts (nanofiltration) can be removed. Ultrafiltration permeate can well be used in paper machine showers to replace fresh water. The quality of the nanofiltration permeate is significantly higher than that of ultrafiltration. The membrane processes can be enhanced by various pre-treatment techniques to produce higher permeate fluxes and to eliminate membrane fouling. Such pre-treatment methods are, e.g., chemical treatment, ozonation and biological treatment. The most cost-effective processes were chemical flocculation, pH adjustment and thermophilic aerobic biological treatment.

  20. Detail of lift wire rope attachment to lift span at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of lift wire rope attachment to lift span at southeast corner. Note rope-adjustment turnbuckle with strap keepers to prevent its rotation, which could pull the bridge out of alignment. A single rope and light-gauge attachment at each corner were adequate for lifting the span because most of its weight was balanced by the two counterweights. - Potomac Edison Company, Chesapeake & Ohio Canal Bridge, Spanning C & O Canal South of U.S. 11, Williamsport, Washington County, MD

  1. The effect of intermittent operation on a wind-powered membrane system for brackish water desalination.

    PubMed

    Park, G L; Schäfer, A I; Richards, B S

    2012-01-01

    Renewable energy powered membrane systems that are directly-connected must take account of both the inherent fluctuations and the intermittency of the energy resource. In order to determine the effect of intermittent operation, a membrane system was tested with variables of (i) amplitude from 60 to 300 W and (ii) length of time with no power from 0.5 to 3 min. This was performed over one hour periods with six on/off cycles to simulate the system operating under intermittent operation for short periods of time when directly-connected to a small wind turbine. The setup used a Filmtec BW30-4040 brackish water reverse osmosis membrane with feed waters of 2,750 mg/L and 5,500 mg/L NaCl. The results showed that the membrane system produced potable water under the majority of intermittency experiments performed. There was a relatively large increase in the average salt concentration of the permeate, especially when the system was off for shorter periods of time (0.5-1 min). Longer periods of no power (1-3 min) did not have as significant an effect on the average water quality. This is important when the need for energy buffering or short term storage is considered for these systems as it shows the potential for improving the overall flux and water quality using temporary energy storage.

  2. Influence of Hydration Level on Polymer and Water Dynamics in Alkaline Anion Exchange Fuel Cell Membranes

    NASA Astrophysics Data System (ADS)

    Tarver, Jacob; Kim, Jenny; Tyagi, Madhu; Soles, Christopher; Tsai, Tsung-Han; Coughlin, Bryan

    2015-03-01

    Triblock copolymers based on poly(chloromethylstyrene)-b-poly(ethylene)-b-poly(chloromethylstyrene) can be quaternized to different extents to yield anion exchange membranes for alkaline fuel cells. In the absence of moisture, these membranes demonstrate bilayer lamellar morphology. Upon high levels of hydration, however, in-situ small angle neutron scattering reveals the emergence of higher-order diffraction peaks. This phenomena has previously been observed in analogous diblock copolymer-based membranes and has been attributed to the induction of a multilayer lamellar morphology in which selective striping of water occurs in the center of the ion-rich domain. By conducting humidity-resolved quasielastic neutron scattering (QENS) measurements using deuterated water, we are able to isolate differences in the pico- to nanosecond timescale dynamics of the hydrogenated membrane upon hydration. QENS measurements in the presence of a hydrogenated water source subsequently permit deconvolution and isolation of the translational and rotational dynamics of water as a function of relative humidity, revealing spatial and temporal changes in polymer and water motion at high levels of hydration.

  3. SIC-BASED HYDROGEN SELECTIVE MEMBRANES FOR WATER-GAS-SHIFT REACTION

    SciTech Connect

    Paul K.T. Liu

    2003-12-01

    A hydrogen selective membrane as a membrane reactor (MR) can significantly improve the power generation efficiency with a reduced capital and operating cost for the waster-gas-shift reaction. Existing hydrogen selective ceramic membranes are not suitable for the proposed MR due to their poor hydrothermal stability. In this project we have focused on the development of innovative silicon carbide (SiC) based hydrogen selective membranes, which can potentially overcome this technical barrier. SiC macro-porous membranes have been successfully fabricated via extrusion of commercially available SiC powder. Also, an SiC hydrogen selective thin film was prepared via our CVD/I technique. This composite membrane demonstrated excellent hydrogen selectivity at high temperature ({approx}600 C). More importantly, this membrane also exhibited a much improved hydrothermal stability at 600 C with 50% steam (atmospheric pressure) for nearly 100 hours. In parallel, we have explored an alternative approach to develop a H{sub 2} selective SiC membrane via pyrolysis of selected pre-ceramic polymers and sol-gel techniques. Building upon the positive progress made in the membrane development study, we conducted an optimization study to develop an H{sub 2} selective SiC membrane with sufficient hydrothermal stability suitable for the WGS environment. In addition, mathematical simulation has been performed to compare the performance of the membrane reactor (MR) vs conventional packed bed reactor for WGS reaction. Our result demonstrates that >99.999% conversion can be accomplished via WGS-MR using the hydrogen selective membrane developed by us. Further, water/CO ratio can be reduced, and >97% hydrogen recovery and <200 ppm CO can be accomplished according to the mathematical simulation. Thus, we believe that the operating economics of WGS can be improved significantly based upon the proposed MR concept. In parallel, gas separations and hydrothermal and long-term-storage stability of the

  4. Bioavailability of endocrine disrupting chemicals (EDCs): Liposome-water partitioning and lipid membrane permeation

    NASA Astrophysics Data System (ADS)

    Kwon, Jung-Hwan

    The bioavailability of endocrine disrupting chemicals (EDCs) is a function of a number of parameters including the ability of the chemical to partition into organic tissue and reach receptor sites within an organism. In this dissertation, equilibrium partition coefficients between water and lipid membrane vesicles and artificial lipid membrane permeability were investigated for evaluating bioavailability of aqueous pollutants. Structurally diverse endocrine disrupting chemicals were chosen as model compounds for partitioning experiments and simple hydrophobic organic chemicals were used for the evaluation of a parallel artificial membrane device developed to mimic bioconcentration rates in fish. Hydrophobic interactions represented by octanol/water partition coefficients (KOWs) were not appropriate for estimating lipid membrane/water partition coefficients (Klipws) for the selected EDCs having a relatively large molar liquid volume (MLV) and containing polar functional groups. Correlations that include MLV and polar surface area (PSA) reduce the predicted value of log K lipw, suggesting that lipid membranes are less favorable than 1-octanol for a hydrophobic solute because of the changes in membrane fluidity and the amount of cholesterol in the lipid bilayers. These results suggested that KOW alone has limited potential for estimating K lipw, and MLV or PSA may be used as additional descriptors for developing quantitative structure-activity relationships (QSARs). The poor correlations between KOW and Klipw observed in this research may be due to the highly organized structure of lipid bilayers. Measured thermodynamic constants demonstrated that the entropy contribution becomes more dominant for more organized liposomes having saturated lipid tails. This implies that entropy-driven partitioning process makes Klipw different from KOW especially for more saturated lipid bilayer membranes. In the parallel artificial membrane system developed, a membrane filter

  5. Elaboration of new ceramic microfiltration membranes from mineral coal fly ash applied to waste water treatment.

    PubMed

    Jedidi, Ilyes; Saïdi, Sami; Khemakhem, Sabeur; Larbot, André; Elloumi-Ammar, Najwa; Fourati, Amine; Charfi, Aboulhassan; Salah, Abdelhamid Ben; Amar, Raja Ben

    2009-12-15

    This work aims to develop a new mineral porous tubular membrane based on mineral coal fly ash. Finely ground mineral coal powder was calcinated at 700 degrees C for about 3 h. The elaboration of the mesoporous layer was performed by the slip-casting method using a suspension made of the mixture of fly-ash powder, water and polyvinyl alcohol (PVA). The obtained membrane was submitted to a thermal treatment which consists in drying at room temperature for 24 h then a sintering at 800 degrees C. SEM photographs indicated that the membrane surface was homogeneous and did not present any macrodefects (cracks, etc...). The average pore diameter of the active layer was 0.25 microm and the thickness was around 20 microm. The membrane permeability was 475 l/h m(2) bar. This membrane was applied to the treatment of the dying effluents generated by the washing baths in the textile industry. The performances in term of permeate flux and efficiency were determined and compared to those obtained using a commercial alumina microfiltration membrane. Almost the same stabilised permeate flux was obtained (about 100 l h(-1)m(-2)). The quality of permeate was almost the same with the two membranes: the COD and color removal was 75% and 90% respectively.

  6. Impact of polymeric membrane filtration of oil sands process water on organic compounds quantification.

    PubMed

    Moustafa, Ahmed M A; Kim, Eun-Sik; Alpatova, Alla; Sun, Nian; Smith, Scott; Kang, Seoktae; Gamal El-Din, Mohamed

    2014-01-01

    The interaction between organic fractions in oil sands process-affected water (OSPW) and three polymeric membranes with varying hydrophilicity (nylon, polyvinylidene fluoride and polytetrafluoroethylene) at different pHs was studied to evaluate the impact of filtration on the quantification of acid-extractable fraction (AEF) and naphthenic acids (NAs). Four functional groups predominated in OSPW (amine, phosphoryl, carboxyl and hydroxyl) as indicated by the linear programming method. The nylon membranes were the most hydrophilic and exhibited the lowest AEF removal at pH of 8.7. However, the adsorption of AEF on the membranes increased as the pH of OSPW decreased due to hydrophobic interactions between the membrane surfaces and the protonated molecules. The use of ultra pressure liquid chromatography-high resolution mass spectrometry (UPLC/HRMS) showed insignificant adsorption of NAs on the tested membranes at pH 8.7. However, 26±2.4% adsorption of NAs was observed at pH 5.3 following the protonation of NAs species. For the nylon membrane, excessive carboxylic acids in the commercial NAs caused the formation of negatively charged assisted hydrogen bonds, resulting in increased adsorption at pH 8.2 (25%) as compared to OSPW (0%). The use of membranes for filtration of soluble compounds from complex oily wastewaters before quantification analysis of AEF and NAs should be examined prior to application.

  7. Permeation liquid membrane as a tool for monitoring bioavailable Pb in natural waters.

    PubMed

    Slaveykova, Vera I; Parthasarathy, Nalini; Buffle, Jacques; Wilkinson, Kevin J

    2004-07-26

    In order to predict metal bioavailability by microorganisms in natural waters, analytical speciation techniques such as the permeation liquid membrane (PLM) are required. A planar sheet PLM has been characterized by measuring Pb fluxes in the absence and presence of tiron and nitrilotriacetic, iminodiacetic, malonic, citric, polyacrylic and fulvic (Suwannee River fulvic, SRFA) acids. Important parameters such as the diffusion coefficient in the membrane phase and the effective distribution coefficient between the solution and membrane were evaluated in order to determine limiting conditions for the overall transport flux through the membrane. Subsequently, the PLM was tested for its ability to predict bioavailability by the freshwater alga, Chlorella kesslerii by comparing Pb PLM fluxes (JPLM) to Pb biouptake fluxes (Jint) in the absence and presence of the synthetic ligands and SRFA. The capability of the PLM to mimic transport across biological membranes was demonstrated, in particular, from the similarity between the accumulated (PLM, algal) Pb vs. time plots under the different conditions. Under membrane transport limiting conditions, fluxes across both the PLM and biological membranes were proportional to the free metal ion and directly correlated to each other in the zone below saturation of the biological metal uptake sites. The correlation between the different fluxes may be used to predict Pb uptake by C. kesslerii in the presence of the synthetic ligands. However, in the presence of SRFA, the observed Jint was much higher than predicted by results obtained either in the absence or presence of the synthetic ligands.

  8. Water diffusion membranes 3 (pervaporation and heat rejection through composite membranes)

    NASA Technical Reports Server (NTRS)

    Cabasso, I.

    1977-01-01

    The problem of waste management in space is discussed for manned space flight. It is shown that such waste can be accounted for in one of four ways: (1) the waste may be dumped into space; (2) it may be accumulated for return to earth; (3) the waste may be separated into two fractions, one fraction (water) to be dumped into space and the remaining portion to be returned to earth; or (4) the waste components may be beneficially reused.

  9. Synthesis of single-crystal-like nanoporous carbon membranes and their application in overall water splitting

    NASA Astrophysics Data System (ADS)

    Wang, Hong; Min, Shixiong; Ma, Chun; Liu, Zhixiong; Zhang, Weiyi; Wang, Qiang; Li, Debao; Li, Yangyang; Turner, Stuart; Han, Yu; Zhu, Haibo; Abou-Hamad, Edy; Hedhili, Mohamed Nejib; Pan, Jun; Yu, Weili; Huang, Kuo-Wei; Li, Lain-Jong; Yuan, Jiayin; Antonietti, Markus; Wu, Tom

    2017-01-01

    Nanoporous graphitic carbon membranes with defined chemical composition and pore architecture are novel nanomaterials that are actively pursued. Compared with easy-to-make porous carbon powders that dominate the porous carbon research and applications in energy generation/conversion and environmental remediation, porous carbon membranes are synthetically more challenging though rather appealing from an application perspective due to their structural integrity, interconnectivity and purity. Here we report a simple bottom-up approach to fabricate large-size, freestanding and porous carbon membranes that feature an unusual single-crystal-like graphitic order and hierarchical pore architecture plus favourable nitrogen doping. When loaded with cobalt nanoparticles, such carbon membranes serve as high-performance carbon-based non-noble metal electrocatalyst for overall water splitting.

  10. Development of an improved membrane for a vapor diffusion water recovery process. [onboard manned spacecraft

    NASA Technical Reports Server (NTRS)

    Rich, T. R.; Mix, T. W.

    1974-01-01

    Recovery of potable water from urine on manned space missions of extended duration was the objective of work aimed at the improvement of membrane performance for the vapor diffusion process (VDR). Kynar, Teflon, PVC, and polysulfone candidate membranes were evaluated from chemical, thermal, mechanical, and fabricating standpoints to determine their suitability for operation in the VDR pervaporation module. Pervaporation rates and other performance characteristics were determined in a breadboard pervaporator test rig. Kynar and Teflon membranes were demonstrated to be chemically stable at pervaporation temperatures in urine pretreated with chromic acid bactericide. The separation of the pervaporator and condenser modules, the use of a recirculating sweep gas to conduct pervaporate to the condenser, and the selection of a hollow fiber membrane configuration for pervaporator module design is recommended as a result of the investigation.

  11. Synthesis of single-crystal-like nanoporous carbon membranes and their application in overall water splitting

    PubMed Central

    Wang, Hong; Min, Shixiong; Ma, Chun; Liu, Zhixiong; Zhang, Weiyi; Wang, Qiang; Li, Debao; Li, Yangyang; Turner, Stuart; Han, Yu; Zhu, Haibo; Abou-hamad, Edy; Hedhili, Mohamed Nejib; Pan, Jun; Yu, Weili; Huang, Kuo-Wei; Li, Lain-Jong; Yuan, Jiayin; Antonietti, Markus; Wu, Tom

    2017-01-01

    Nanoporous graphitic carbon membranes with defined chemical composition and pore architecture are novel nanomaterials that are actively pursued. Compared with easy-to-make porous carbon powders that dominate the porous carbon research and applications in energy generation/conversion and environmental remediation, porous carbon membranes are synthetically more challenging though rather appealing from an application perspective due to their structural integrity, interconnectivity and purity. Here we report a simple bottom–up approach to fabricate large-size, freestanding and porous carbon membranes that feature an unusual single-crystal-like graphitic order and hierarchical pore architecture plus favourable nitrogen doping. When loaded with cobalt nanoparticles, such carbon membranes serve as high-performance carbon-based non-noble metal electrocatalyst for overall water splitting. PMID:28051082

  12. State of the reverse osmosis membrane of sea water corso plant desalination (Algiers)

    NASA Astrophysics Data System (ADS)

    Abdessemed, D.; Hamouni, S.; Nezzal, G.

    2009-11-01

    Seawater reverse osmosis (SWRO) desalination is being increasingly emphasized as a strategy for conservation of limited resources of freshwater. Although desalination has been developed for the last few decades, the SWRO operation is still affected by membrane fouling. The membrane fouling of SWRO has a significant impact on operation of desalination plants. We follow the evolution of the permeate conductivity during three months of the sea water Corso (Algiers) plant desalination. The purpose of this work is to conduct an autopsy of fouled membranes in seawater using the scanning electron microscopy (SEM) coupled by an analysis EDX. This membrane shows a change of the surface morphology, which justifies the abrupt increase in the conductivity of the permeate in May 2006. In order to identify the nature of the fouling deposit, we analysed this deposit by Xrays diffraction (XRD).

  13. Use of charge-selective membranes for electrodialytic desalination of mineralized drainage collector waters

    SciTech Connect

    Grebenyuk, V.D.; Veisov, B.K.; Chebotareva, R.D.; Braude, K.P.; Nefedova, G.Z.

    1986-10-10

    The purpose of this work was to examine the possibility of desalination, without preliminary softening, of drainage collector waters of a medium degree mineralization, represented by a simulated solution of the same cation composition, with the use of single-charge-selective membranes. A cation-exchange membrane obtained by modification of the commercial MK-100 membrane with ethylenediamine (6), was used for this purpose. The modification was effected by treatment of the chlorosulfonated matrix with aqueous ethylenediamine solution at room temperature. The matrix, aminated on one side was then treated with concentrated NaOH solution to convert unreacted sulfonyl chloride groups into sulfo. The capacity of the modified MK-100M membrane for sulfo groups was 1.8 meq/g. The possibility of obtaining highly concentrated brines was examined at the same time.

  14. Emergency membrane contactor based absorption system for ammonia leaks in water treatment plants.

    PubMed

    Shao, Jiahui; Fang, Xuliang; He, Yiliang; Jin, Qiang

    2008-01-01

    Abstract Because of the suspected health risks of trihalomethanes (THMs), more and more water treatment plants have replaced traditional chlorine disinfection process with chloramines but often without the proper absorption system installed in the case of ammonia leaks in the storage room. A pilot plant membrane absorption system was developed and installed in a water treatment plant for this purpose. Experimentally determined contact angle, surface tension, and corrosion tests indicated that the sulfuric acid was the proper choice as the absorbent for leaking ammonia using polypropylene hollow fiber membrane contactor. Effects of several operating conditions on the mass transfer coefficient, ammonia absorption, and removal efficiency were examined, including the liquid concentration, liquid velocity, and feed gas concentration. Under the operation conditions investigated, the gas absorption efficiency over 99.9% was achieved. This indicated that the designed pilot plant membrane absorption system was effective to absorb the leaking ammonia in the model storage room. The removal rate of the ammonia in the model storage room was also experimentally and theoretically found to be primarily determined by the ammonia suction flow rate from the ammonia storage room to the membrane contactor. The ammonia removal rate of 99.9% was expected to be achieved within 1.3 h at the ammonia gas flow rate of 500 m3/h. The success of the pilot plant membrane absorption system developed in this study illustrated the potential of this technology for ammonia leaks in water treatment plant, also paved the way towards a larger scale application.

  15. Recent advances in cellulose and chitosan based membranes for water purification: A concise review.

    PubMed

    Thakur, Vijay Kumar; Voicu, Stefan Ioan

    2016-08-01

    Recently membrane technology has emerged as a new promising and pervasive technology due to its innate advantages over traditional technologies such as adsorption, distillation and extraction. In this article, some of the recent advances in developing polymeric composite membrane materials for water purification from natural polysaccharide based polymers namely cellulose derivatives and chitosan are concisely reviewed. The impact of human social, demographic and industrial evolution along with expansion through environment has significantly affected the quality of water by pollution with large quantities of pesticides, minerals, drugs or other residues. At the forefront of decontamination and purification techniques, we found the membrane materials from polymers as a potential alternative. In an attempt to reduce the number of technical polymers widely used in the preparation of membranes, many researchers have reported new solutions for desalination or retention of organic yeasts, based on bio renewable polymers like cellulose derivatives and chitosan. These realizations are presented and discussed in terms of the most important parameters of membrane separation especially water flux and retention in this article.

  16. Technical and economical evaluation of water recycling in the carwash industry with membrane processes.

    PubMed

    Boussu, K; Eelen, D; Vanassche, S; Vandecasteele, C; Van der Bruggen, B; Van Baelen, G; Colen, W; Vanassche, S

    2008-01-01

    In the carwash industry, water recycling is necessary to be in accordance with present and upcoming environmental laws. As this is not possible with traditional techniques, membrane processes (like ultrafiltration (UF) and nanofiltration (NF)) are technically and economically evaluated in this study. Concerning the technical part, there needs to be a compromise between a high permeate permeability on the one hand and a high permeate purity on the other hand. Depending on the use of the purified wastewater, ultrafiltration (to recycle wastewater in the main wash cycle) or nanofiltration (to recycle wastewater in the rinsing step) would be the optimal choice. Concerning the financial part, the implementation of membrane processes in the wastewater purification installation is economically feasible, especially when expensive tap water is used as pure water. These positive evaluations imply that membrane processes can be useful to recycle wastewater in the carwash industry, on condition that the right membrane type (with the least membrane fouling) and the right process format (e.g., hybrid process of UF and/or NF with a biological treatment) is selected.

  17. Self-assembly in Nafion membranes upon hydration: water mobility and adsorption isotherms.

    PubMed

    Vishnyakov, Aleksey; Neimark, Alexander V

    2014-09-25

    By means of dissipative particle dynamics (DPD) and Monte Carlo (MC) simulations, we explored geometrical, transport, and sorption properties of hydrated Nafion-type polyelectrolyte membranes. Composed of a perfluorinated backbone with sulfonate side chains, Nafion self-assembles upon hydration and segregates into interpenetrating hydrophilic and hydrophobic subphases. This segregated morphology determines the transport properties of Nafion membranes that are widely used as compartment separators in fuel cells and other electrochemical devices, as well as permselective diffusion barriers in protective fabrics. We introduced a coarse-grained model of Nafion, which accounts explicitly for polymer rigidity and electrostatic interactions between anionic side chains and hydrated metal cations. In a series of DPD simulations with increasing content of water, a classical percolation transition from a system of isolated water clusters to a 3D network of hydrophilic channels was observed. The hydrophilic subphase connectivity and water diffusion were studied by constructing digitized replicas of self-assembled morphologies and performing random walk simulations. A non-monotonic dependence of the tracer diffusivity on the water content was found. This unexpected behavior was explained by the formation of large and mostly isolated water domains detected at high water content and high equivalent polymer weight. Using MC simulations, we calculated the chemical potential of water in the hydrated polymer and constructed the water sorption isotherms, which extended to the oversaturated conditions. We determined that the maximum diffusivity and the onset of formation of large water domains corresponded to the saturation conditions at 100% humidity. The oversaturated membrane morphologies generated in the canonical ensemble DPD simulations correspond to the metastable and unstable states of Nafion membrane that are not realized in the experiments.

  18. The Membrane Protein LasM Promotes the Culturability of Legionella pneumophila in Water

    PubMed Central

    Li, Laam; Faucher, Sébastien P.

    2016-01-01

    The water-borne pathogen Legionella pneumophila (Lp) strongly expresses the lpg1659 gene in water. This gene encodes a hypothetical protein predicted to be a membrane protein using in silico analysis. While no conserved domains were identified in Lpg1659, similar proteins are found in many Legionella species and other aquatic bacteria. RT-qPCR showed that lpg1659 is positively regulated by the alternative sigma factor RpoS, which is essential for Lp to survive in water. These observations suggest an important role of this novel protein in the survival of Lp in water. Deletion of lpg1659 did not affect cell morphology, membrane integrity or tolerance to high temperature. Moreover, lpg1659 was dispensable for growth of Lp in rich medium, and during infection of the amoeba Acanthamoeba castellanii and of THP-1 human macrophages. However, deletion of lpg1659 resulted in an early loss of culturability in water, while over-expression of this gene promoted the culturability of Lp. Therefore, these results suggest that lpg1659 is required for Lp to maintain culturability, and possibly long-term survival, in water. Since the loss of culturability observed in the absence of Lpg1659 was complemented by the addition of trace metals into water, this membrane protein is likely a transporter for acquiring essential trace metal for maintaining culturability in water and potentially in other metal-deprived conditions. Given its role in the survival of Lp in water, Lpg1659 was named LasM for Legionella aquatic survival membrane protein. PMID:27734007

  19. Toward a predictive understanding of water and charge transport in proton exchange membranes.

    PubMed

    Selvan, Myvizhi Esai; Calvo-Muñoz, Elisa; Keffer, David J

    2011-03-31

    An analytical model for water and charge transport in highly acidic and highly confined systems such as proton exchange membranes of fuel cells is developed and compared to available experimental data. The model is based on observations from both experiment and multiscale simulation. The model accounts for three factors in the system including acidity, confinement, and connectivity. This model has its basis in the molecular-level mechanisms of water transport but has been coarse-grained to the extent that it can be expressed in an analytical form. The model uses the concentration of H(3)O(+) ion to characterize acidity, interfacial surface area per water molecule to characterize confinement, and percolation theory to describe connectivity. Several important results are presented. First, an integrated multiscale simulation approach including both molecular dynamics simulation and confined random walk theory is capable of quantitatively reproducing experimentally measured self-diffusivities of water in the perfluorinated sulfonic acid proton exchange membrane material, Nafion. The simulations, across a range of hydration conditions from minimally hydrated to fully saturated, have an average error for the self-diffusivity of water of 16% relative to experiment. Second, accounting for three factors-acidity, confinement, and connectivity-is necessary and sufficient to understand the self-diffusivity of water in proton exchange membranes. Third, an analytical model based on percolation theory is capable of quantitatively reproducing experimentally measured self-diffusivities of both water and charge in Nafion across a full range of hydration.

  20. Highly permeable double-skinned forward osmosis membranes for anti-fouling in the emulsified oil-water separation process.

    PubMed

    Duong, Phuoc H H; Chung, Tai-Shung; Wei, Shawn; Irish, Lana

    2014-04-15

    Forward osmosis (FO) has attracted wide attention in recent years. However, the FO performance may be restricted due to internal concentration polarization (ICP) and fast fouling propensity that occurs in the membrane sublayer. Particularly, these problems significantly affect the membrane performance when treating highly contaminated oily wastewater. Recently, double-skinned flat sheet cellulose acetate (CA) membranes consisting of two selective skins via the phase inversion method have demonstrated less ICP and fouling propensity over typical single-skinned membranes. However, these membranes exhibit low water fluxes of <12 LMH under 2 M NaCl draw solution. Therefore, a novel double-skinned FO membrane with a high water flux has been aimed for in this study for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between (i) a truly dense skin for salt rejection and (ii) a fairly loose dense skin for emulsified oil particle rejection. The former dense skin is a polyamide synthesized via interfacial polymerization, while the latter one is a self-assembled sulfonated pentablock copolymer (Nexar copolymer) layer. The resultant double-skinned membrane exhibits a high water flux of 17.2 LMH and a low reverse salt transport of 4.85 gMH using 0.5 M NaCl as the draw solution and DI water as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation.

  1. Fresh water production from municipal waste water with RO membrane technology and its application for agriculture and industry in arid area

    NASA Astrophysics Data System (ADS)

    Yokoyama, F.

    2015-04-01

    One of the biggest problems of the 21st century is the global water shortage. Therefore it is difficult to increase the quantity of conventional water resources such as surface water and groundwater for agriculture and industry in arid area. Technical advancement in water treatment membrane technology including RO membrane has been remarkable especially in recent years. As the pore size of RO membrane is less than one nanometer, it is possible to produce the fresh water, which satisfies the drinking water quality standards, with utilizing RO membrane. In this report a new fresh water resource from municipal waste water is studied to apply to the plant factory which is the water saving type agriculture and industry in arid area.

  2. Modification of poly(vinylidene fluoride) ultrafiltration membranes with poly(vinyl alcohol) for fouling control in drinking water treatment.

    PubMed

    Du, Jennifer R; Peldszus, Sigrid; Huck, Peter M; Feng, Xianshe

    2009-10-01

    A commercial poly(vinylidene fluoride) flat sheet membrane was modified by surface coating with a dilute poly(vinyl alcohol) (PVA) aqueous solution followed by solid-vapor interfacial crosslinking. The resulting PVA layer increased membrane smoothness and hydrophilicity and resulted in comparable pure water permeation between the modified and unmodified membranes. Fouling tests using a 5 mg/L protein solution showed that a short period of coating and crosslinking improved the anti-fouling performance. After 18 h ultrafiltration of a surface water with a TOC of approximately 7 mg C/L, the flux of the modified membrane was twice as high as that of the unmodified membrane. The improved fouling resistance of the modified membrane was related to the membrane physiochemical properties, which were confirmed by pure water permeation, X-ray photoelectron spectroscopy, and contact angle, zeta potential and roughness measurements.

  3. Cell membrane water exchange effects in prostate DCE-MRI

    NASA Astrophysics Data System (ADS)

    Li, Xin; Priest, Ryan A.; Woodward, William J.; Siddiqui, Faisal; Beer, Tomasz M.; Garzotto, Mark G.; Rooney, William D.; Springer, Charles S.

    2012-05-01

    Prostate Dynamic-Contrast-Enhanced (DCE) MRI often exhibits fast and extensive global contrast reagent (CR) extravasation - measured by Ktrans, a pharmacokinetic parameter proportional to its rate. This implies that the CR concentration [CR] is high in the extracellular, extravascular space (EES) during a large portion of the DCE-MRI study. Since CR is detected indirectly, through water proton signal change, the effects of equilibrium transcytolemmal water exchange may be significant in the data and thus should be admitted in DCE-MRI pharmacokinetic modeling. The implications for parameter values were investigated through simulations, and analyses of actual prostate data, with different models. Model parameter correlation and precision were also explored. A near-optimal version of the exchange-sensitized model was found. Our results indicate that ΔKtrans (the Ktrans difference returned by this version and a model assuming exchange to be effectively infinitely fast) may be a very useful biomarker for discriminating malignant from benign prostate tissue. Using an exchange-sensitized model, we find that the mean intracellular water lifetime (τi) - an exchange measure - can be meaningfully mapped for the prostate. Our results show prostate glandular zone differences in τi values.

  4. Cell membrane water exchange effects in prostate DCE-MRI.

    PubMed

    Li, Xin; Priest, Ryan A; Woodward, William J; Siddiqui, Faisal; Beer, Tomasz M; Garzotto, Mark G; Rooney, William D; Springer, Charles S

    2012-05-01

    Prostate Dynamic-Contrast-Enhanced (DCE) MRI often exhibits fast and extensive global contrast reagent (CR) extravasation - measured by K(trans), a pharmacokinetic parameter proportional to its rate. This implies that the CR concentration [CR] is high in the extracellular, extravascular space (EES) during a large portion of the DCE-MRI study. Since CR is detected indirectly, through water proton signal change, the effects of equilibrium transcytolemmal water exchange may be significant in the data and thus should be admitted in DCE-MRI pharmacokinetic modeling. The implications for parameter values were investigated through simulations, and analyses of actual prostate data, with different models. Model parameter correlation and precision were also explored. A near-optimal version of the exchange-sensitized model was found. Our results indicate that ΔK(trans) (the K(trans) difference returned by this version and a model assuming exchange to be effectively infinitely fast) may be a very useful biomarker for discriminating malignant from benign prostate tissue. Using an exchange-sensitized model, we find that the mean intracellular water lifetime (τ(i)) - an exchange measure - can be meaningfully mapped for the prostate. Our results show prostate glandular zone differences in τ(i) values.

  5. Effect of porous polymer films (track membranes) on the isothermal evaporation kinetics of water

    NASA Astrophysics Data System (ADS)

    Novikov, S. N.; Ermolaeva, A. I.; Timoshenkov, S. P.; Korobova, N. E.; Goryunova, E. P.

    2016-06-01

    The kinetics of isothermal evaporation of distilled water that was in remote (10-15-mm) contact with porous polymer films (track membranes (TMs)) was studied by microgravimetry (derivatograph). When the H2O-TM system contained a disperse medium, the supramolecular structure of water changed, and the number of clusters (coherent domains) drastically decreased. The extraction of the light phase from liquid water was correlated with the chemisorption of H2O molecules containing the para-isomer of hydrogen, which predominantly form coherent domains of water.

  6. Application of membrane processes in fractionation of elements in river water.

    PubMed

    Wu, N; Wyart, Y; Rose, J; Angeletti, B; Moulin, P

    2015-01-01

    The influence of wastewater treatment plant (WWTP) effluents from one microelectronic industrial zone on element concentrations and partitioning in river water was investigated. The stepwise membrane filtration is used to distinguish different size fractions including large particulate (>18 μm), particulate (0.2-18 μm), colloidal/nanoparticle (10 kDa-0.2 μm) and truly dissolved fractions (<10 kDa) in river water samples and WWTP effluents. Results demonstrated that anthropogenic inputs (WWTP effluents and industrial area) had an important influence on concentrations and partitioning of some elements in river water. Mass balance results showed that membrane filtration processes could realize a good fractionation for many elements (good recoveries) in water samples. Flux decline during 0.2 μm and 10 kDa filtrations were analyzed, and corresponding fouling mechanisms are discussed.

  7. Reclaiming agricultural drainage water with nanofiltration membranes: Imperial Valley, California, USA

    USGS Publications Warehouse

    Kharaka, Y.K.; Schroeder, R.A.; Setmire, J.G.; ,

    2003-01-01

    We conducted pilot-scale field experiments using nanofiltration membranes to lower the salinity and remove Se, As and other toxic contaminants from saline agricultural wastewater in the Imperial Valley, California, USA. Farmlands in the desert climate (rainfall - 7.4 cm/a) of Imperial Valley cover -200,000 ha that are irrigated with water (-1.7 km3 annually) imported from the Colorado River. The salinity (-850 mg/L) and concentration of Se (-2.5 ??g/L) in the Colorado River water are high and evapotranpiration further concentrates salts in irrigation drainage water, reaching salinities of 3,000-15,000 mg/L TDS and a median Se value of -30 ??g/L. Experiments were conducted with two commercially available nanofiltration membranes, using drainage water of varying composition, and with or without the addition of organic precipitation inhibitors. Results show that these membranes selectively remove more than 95% of Se, SO4, Mo, U and DOC, and -30% of As from this wastewater. Low percentages of Cl, NO3 and HCO3, with enough cations to maintain electrical neutrality also were removed. The product water treated by these membranes comprised more than 90% of the wastewater tested. Results indicate that the treated product water from the Alamo River likely will have less than 0.2 ??g/L Se, salinity of 300-500 mg/L TDS and other chemical concentrations that meet the water quality criteria for irrigation and potable use. Because acceptability is a major issue for providing treated wastewater to urban centers, it may be prudent to use the reclaimed water for irrigation and creation of lower salinity wetlands near the Salton Sea; an equivalent volume of Colorado River water can then be diverted for the use of increasing populations of San Diego and other urban centers in southern California. Nanofiltration membranes yield greater reclaimed-water output and require lower pressure and less pretreatment, and therefore are generally more cost effective than traditional reverse

  8. Robust Alginate-Catechol@Polydopamine Free-Standing Membranes Obtained from the Water/Air Interface.

    PubMed

    Ponzio, Florian; Le Houerou, Vincent; Zafeiratos, Spyridon; Gauthier, Christian; Garnier, Tony; Jierry, Loic; Ball, Vincent

    2017-03-07

    The formation of polydopamine composite membranes at the water/air interface using different chemical strategies is reported. The use of either small molecules (urea, pyrocatechol) or polymers paves the way to understand which kind of compounds can be used for the formation of PDA-composite free-standing membranes produced at the water/air interface. On the basis of these screening results, we have found that alginate grafted with catechol groups allows the formation of robust free-standing films with asymmetric composition, stimuli-responsiveness, and self-healing properties. The stickiness of these membranes depends on the relative humidity, and its adhesion behavior on PDMS was characterized using the JKR method. Thus, alginate-catechol polydopamine films appear as a new class of PDA composites, mechanically robust through covalent cross-linking and based on fully biocompatible constituting partners. These results open the door to potential applications in the biomedical field.

  9. The Structure of the Yeast Plasma Membrane SNARE Complex Reveals Destabilizing Water Filled Cavities

    SciTech Connect

    Strop, P.; Kaiser, S.E.; Vrljic, M.; Brunger, A.T.

    2009-05-26

    Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins form a complex that leads to membrane fusion between vesicles, organelles, and plasma membrane in all eukaryotic cells. We report the 1.7{angstrom} resolution structure of the SNARE complex that mediates exocytosis at the plasma membrane in the yeast Saccharomyces cerevisiae. Similar to its neuronal and endosomal homologues, the S. cerevisiae SNARE complex forms a parallel four-helix bundle in the center of which is an ionic layer. The S. cerevisiae SNARE complex exhibits increased helix bending near the ionic layer, contains water-filled cavities in the complex core, and exhibits reduced thermal stability relative to mammalian SNARE complexes. Mutagenesis experiments suggest that the water-filled cavities contribute to the lower stability of the S. cerevisiae complex.

  10. Performance evaluation of attached growth membrane bioreactor for treating polluted surface water.

    PubMed

    Li, Lu; Suwanate, Siwaporn; Visvanathan, C

    2017-01-25

    Attached growth membrane bioreactor (aMBR) process was investigated for treating polluted surface water with CODMn around 10mg/L of raw water. Lab scale reactors, aMBR with 15% PVA-gel as carrier and conventional membrane filtration reactor (MF) were tested in parallel. aMBR achieved two times higher CODMn removal than MF system. Ammonia removal occurred almost completely in both MF and aMBR system - around 94% and 96%, respectively. Permeate turbidity was almost totally removed while UV254 removal was around 15% in MF and 20% in aMBR system. aMBR system largely mitigated membrane fouling and prolonged the system operation time. Results showed 2h hydraulic retention time provided relatively higher removal efficiency and stable operation performance. Modified Stover Kincannon model was able to match the aMBR system.

  11. Aquaporin-1 in the peritoneal membrane: Implications for water transport across capillaries and peritoneal dialysis.

    PubMed

    Devuyst, Olivier; Ni, Jie

    2006-08-01

    Peritoneal dialysis (PD) is an established mode of renal replacement therapy, based on the exchange of fluid and solutes between blood in peritoneal capillaries and a dialysate that has been introduced in the peritoneal cavity. The dialysis involves diffusive and convective transports and osmosis through the highly vascularized peritoneal membrane. Computer simulations predicted that the membrane contains ultrasmall pores (radius < 3 A) responsible for the transport of solute-free water across the capillary endothelium during crystalloid osmosis. The distribution of the water channel aquaporin-1 (AQP1), as well as its molecular structure ensuring an exquisite selectivity for water perfectly fit with the characteristics of the ultrasmall pore. Treatment with corticosteroids induces the expression of AQP1 in peritoneal capillaries and increases water permeability and ultrafiltration in rats, without affecting the osmotic gradient and the permeability for small solutes. Studies in knockout mice provided further evidence that osmotically-driven water transport across the peritoneal membrane is mediated by AQP1. AQP1 and endothelial NO synthase (eNOS) show a distinct regulation within the endothelium lining peritoneal capillaries. In acute peritonitis, the upregulation of eNOS and increased release of NO dissipate the osmotic gradient and result in ultrafiltration failure, despite the unchanged expression of AQP1. These data illustrate the potential of the peritoneal membrane to investigate the role and regulation of AQP1 in the endothelium. They also emphasize the critical role of AQP1 during peritoneal dialysis and suggest that manipulating AQP1 expression may be used to increase water permeability across the peritoneal membrane.

  12. Concentrations of anesthetics across the water-membrane interface; the Meyer-Overton hypothesis revisited

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Wilson, M. A.; New, M. H.; Chipot, C.

    1998-01-01

    The free energies of transferring a variety of anesthetic and nonanesthetic compounds across water-oil and water-membrane interfaces were obtained using computer simulations. Anesthetics exhibit greatly enhanced concentrations at these interfaces, compared to nonanesthetics. The substitution of the interfacial solubilites of the anesthetics for their bulk lipid solubilities in the Meyer-Overton relation, was found to give a better correlation, indicating that the potency of an anesthetic is directly proportional to its solubility at the interface.

  13. Novel Nonporous Fouling-Resistant Enzymatic Composite Membranes for Waste Water Treatment

    DTIC Science & Technology

    2007-11-02

    aromatic residues, and pronase from. Streptomyces griseus is unusually non-specific. Lipase PS from Burkholderia cepacia was reported to exhibit the...Waste Water N00014-02-1-0445 Treatment 5b. GRANT NUMBER N00014-02-1-0445 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Benny D. Freeman...oxide) was prepared. These membrane materials showed high water uptake and excellent resistance to bovine serum albumin (BSA) fouling. By controlling

  14. Development of a two-stage membrane-based wash-water reclamation subsystem

    NASA Technical Reports Server (NTRS)

    Mccray, S. B.

    1988-01-01

    A two-stage membrane-based subsystem was designed and constructed to enable the recycle of wash waters generated in space. The first stage is a fouling-resistant tube-side-feed hollow-fiber ultrafiltration module, and the second stage is a spiral-wound reverse-osmosis module. Throughout long-term tests, the subsystem consistently produced high-quality permeate, processing actual wash water to 95 percent recovery.

  15. A Trade Study of Two Membrane-Aerated Biological Water Processors

    NASA Technical Reports Server (NTRS)

    Allada, Ram; Lange, Kevin; Vega. Leticia; Roberts, Michael S.; Jackson, Andrew; Anderson, Molly; Pickering, Karen

    2011-01-01

    Biologically based systems are under evaluation as primary water processors for next generation life support systems due to their low power requirements and their inherent regenerative nature. This paper will summarize the results of two recent studies involving membrane aerated biological water processors and present results of a trade study comparing the two systems with regards to waste stream composition, nutrient loading and system design. Results of optimal configurations will be presented.

  16. Graphene Oxide as an Effective Barrier on a Porous Nanofibrous Membrane for Water Treatment.

    PubMed

    Wang, Jianqiang; Zhang, Pan; Liang, Bin; Liu, Yuxuan; Xu, Tao; Wang, Lifang; Cao, Bing; Pan, Kai

    2016-03-09

    A novel graphene oxide (GO)-based nanofiltration membrane on a highly porous polyacrylonitrile nanofibrous mat (GO@PAN) is prepared for water treatment applications. GO with large lateral size (more than 200 μm) is first synthesized through an improved Hummers method and then assembled on a highly porous nanofibrous mat by vacuum suction method. The prepared GO@PAN membrane is characterized by scanning electron microscopy, transmission electron microscopy, Raman spectrum, X-ray diffraction, and so forth. The results show that graphene oxide can form a barrier on the top of a PAN nanofibrous mat with controllable thickness. The obtained graphene oxide layer exhibits "ideal" pathways (hydrophobic nanochannel) for water molecules between the well-stacked GO nanosheets. Water flux under an extremely low external pressure (1.0 bar) significantly increased due to the unique structure of the GO layer and nanofibrous support. Furthermore, the GO@PAN membrane shows high rejection performance (nearly 100% rejection of Congo red and 56.7% for Na2SO4). A hydrophilic-hydrophobic "gate"-na