Science.gov

Sample records for adsorb significant amounts

  1. Determination of maximal amount of minor gases adsorbed in a shale sample by headspace gas chromatography.

    PubMed

    Zhang, Chun-Yun; Hu, Hui-Chao; Chai, Xin-Sheng; Pan, Lei; Xiao, Xian-Ming

    2014-02-07

    In this paper, we present a novel method for determining the maximal amount of ethane, a minor gas species, adsorbed in a shale sample. The method is based on the time-dependent release of ethane from shale samples measured by headspace gas chromatography (HS-GC). The study includes a mathematical model for fitting the experimental data, calculating the maximal amount gas adsorbed, and predicting results at other temperatures. The method is a more efficient alternative to the isothermal adsorption method that is in widespread use today.

  2. 29 CFR 4.140 - Significance of contract amount.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Significance of contract amount. 4.140 Section 4.140 Labor Office of the Secretary of Labor LABOR STANDARDS FOR FEDERAL SERVICE CONTRACTS Application of the McNamara-O'Hara Service Contract Act Determining Amount of Contract § 4.140 Significance of contract...

  3. Relationship between the Amount of Bitter Substances Adsorbed onto Lipid/Polymer Membrane and the Electric Response of Taste Sensors

    PubMed Central

    Toko, Kiyoshi; Hara, Daichi; Tahara, Yusuke; Yasuura, Masato; Ikezaki, Hidekazu

    2014-01-01

    The bitterness of bitter substances can be measured by the change in the membrane electric potential caused by adsorption (CPA) using a taste sensor (electronic tongue). In this study, we examined the relationship between the CPA value due to an acidic bitter substance and the amount of the bitter substance adsorbed onto lipid/polymer membranes, which contain different lipid contents, used in the taste sensor. We used iso-α-acid which is an acidic bitter substance found in several foods and beverages. The amount of adsorbed iso-α-acid, which was determined by spectroscopy, showed a maximum at the lipid concentration 0.1 wt % of the membrane, and the same phenomenon was observed for the CPA value. At the higher lipid concentration, however, the amount adsorbed decreased and then remained constant, while the CPA value decreased monotonically to zero. This constant adsorption amount was observed when the membrane potential in the reference solution did not change with increasing lipid concentration. The decrease in CPA value in spite of the constant adsorption amount is caused by a decrease in the sensitivity of the membrane as the surface charge density increases. The reason why the peaks appeared in both the CPA value and adsorption amount is based on the contradictory adsorption properties of iso-α-acid. The increasing charged lipid concentration of the membrane causes an increasing electrostatic attractive interaction between iso-α-acid and the membrane, but simultaneously causes a decreasing hydrophobic interaction that results in decreasing adsorption of iso-α-acid, which also has hydrophobic properties, onto the membrane. Estimates of the amount of adsorption suggest that iso-α-acid molecules are adsorbed onto both the surface and interior of the membrane. PMID:25184491

  4. Mesoporous Silica Nanoparticles as an Adsorbent for Preconcentration and Determination of Trace Amount of Nickel in Environmental Samples by Atom Trap Flame Atomic Absorption Spectrometry

    NASA Astrophysics Data System (ADS)

    Shirkhanloo, H.; Falahnejad, M.; Zavvar Mousavi, H.

    2016-01-01

    A rapid enrichment method based on solid-phase extraction (SPE) has been established for preconcentration and separation of trace Ni(II) ions in water samples prior to their determination by atom trap flame atomic absorption spectrometry. A column filled with bulky NH2-UVM7 was used as the novel adsorbent. Under optimal conditions, the linear range, limit of detection (LOD), and preconcentration factor (PF) were 3-92 μg/L, 0.8 μg/L, and 100, respectively. The validity of the method was checked by the standard reference material.

  5. Thermal Behavior of d-Ribose Adsorbed on Silica: Effect of Inorganic Salt Coadsorption and Significance for Prebiotic Chemistry.

    PubMed

    Akouche, Mariame; Jaber, Maguy; Zins, Emilie-Laure; Maurel, Marie-Christine; Lambert, Jean-Francois; Georgelin, Thomas

    2016-10-24

    Understanding ribose reactivity is a crucial step in the "RNA world" scenario because this molecule is a component of all extant nucleotides that make up RNA. In solution, ribose is unstable and susceptible to thermal destruction. We examined how ribose behaves upon thermal activation when adsorbed on silica, either alone or with the coadsorption of inorganic salts (MgCl2 , CaCl2 , SrCl2 , CuCl2 , FeCl2 , FeCl3 , ZnCl2 ). A combination of (13) C NMR, in situ IR, and TGA analyses revealed a variety of phenomena. When adsorbed alone, ribose remains stable up to 150 °C, at which point ring opening is observed, together with minor oxidation to a lactone. All the metal salts studied showed specific interactions with ribose after dehydration, resulting in the formation of polydentate metal ion complexes. Anomeric equilibria were affected, generally favoring ribofuranoses. Zn(2+) stabilized ribose up to higher temperatures than bare silica (180 to 200 °C). Most other cations had an adverse effect on ribose stability, with ring opening already upon drying at 70 °C. In addition, alkaline earth cations catalyzed the dehydration of ribose to furfural and, to variable degrees, its further decarbonylation to furan. Transition-metal ions with open d-shells took part in redox reactions with ribose, either as reagents or as catalysts. These results allow the likelihood of prebiotic chemistry scenarios to be evaluated, and may also be of interest for the valorization of biomass-derived carbohydrates by heterogeneous catalysis.

  6. Meteorites at Meridiani Planum provide evidence for significant amounts of surface and near-surface water on early Mars

    USGS Publications Warehouse

    Fairen, Alberto G.; Dohm, James M.; Baker, Victor R.; Thompson, Shane D.; Mahaney, William C.; Herkenhoff, Kenneth E.; Rodriguez, J. Alexis P.; Davila, Alfonso F.; Schulze-Makuch, Dirk; El Maarry, M. Ramy; Uceda, Esther R.; Amils, Ricardo; Miyamoto, Hirdy; Kim, Kyeong J.; Anderson, Robert C.; McKay, Christopher P.

    2011-01-01

    Six large iron meteorites have been discovered in the Meridiani Planum region of Mars by the Mars Exploration Rover Opportunity in a nearly 25 km-long traverse. Herein, we review and synthesize the available data to propose that the discovery and characteristics of the six meteorites could be explained as the result of their impact into a soft and wet surface, sometime during the Noachian or the Hesperian, subsequently to be exposed at the Martian surface through differential erosion. As recorded by its sediments and chemical deposits, Meridiani has been interpreted to have undergone a watery past, including a shallow sea, a playa, an environment of fluctuating ground water, and/or an icy landscape. Meteorites could have been encased upon impact and/or subsequently buried, and kept underground for a long time, shielded from the atmosphere. The meteorites apparently underwent significant chemical weathering due to aqueous alteration, as indicated by cavernous features that suggest differential acidic corrosion removing less resistant material and softer inclusions. During the Amazonian, the almost complete disappearance of surface water and desiccation of the landscape, followed by induration of the sediments and subsequent differential erosion and degradation of Meridiani sediments, including at least 10–80 m of deflation in the last 3–3.5 Gy, would have exposed the buried meteorites. We conclude that the iron meteorites support the hypothesis that Mars once had a denser atmosphere and considerable amounts of water and/or water ice at and/or near the surface.

  7. Meteorites at Meridiani Planum provide evidence for significant amounts of surface and near-surface water on early Mars

    USGS Publications Warehouse

    Fairen, A.G.; Dohm, J.M.; Baker, V.R.; Thompson, S.D.; Mahaney, W.C.; Herkenhoff, K. E.; Rodriguez, J.A.P.; Davila, A.F.; Schulze-Makuch, D.; El Maarry, M.R.; Uceda, E.R.; Amils, R.; Miyamoto, H.; Kim, K.J.; Anderson, R.C.; McKay, C.P.

    2011-01-01

    Six large iron meteorites have been discovered in the Meridiani Planum region of Mars by the Mars Exploration Rover Opportunity in a nearly 25km-long traverse. Herein, we review and synthesize the available data to propose that the discovery and characteristics of the six meteorites could be explained as the result of their impact into a soft and wet surface, sometime during the Noachian or the Hesperian, subsequently to be exposed at the Martian surface through differential erosion. As recorded by its sediments and chemical deposits, Meridiani has been interpreted to have undergone a watery past, including a shallow sea, a playa, an environment of fluctuating ground water, and/or an icy landscape. Meteorites could have been encased upon impact and/or subsequently buried, and kept underground for a long time, shielded from the atmosphere. The meteorites apparently underwent significant chemical weathering due to aqueous alteration, as indicated by cavernous features that suggest differential acidic corrosion removing less resistant material and softer inclusions. During the Amazonian, the almost complete disappearance of surface water and desiccation of the landscape, followed by induration of the sediments and subsequent differential erosion and degradation of Meridiani sediments, including at least 10-80m of deflation in the last 3-3.5Gy, would have exposed the buried meteorites. We conclude that the iron meteorites support the hypothesis that Mars once had a denser atmosphere and considerable amounts of water and/or water ice at and/or near the surface. ?? The Meteoritical Society, 2011.

  8. Adsorbent phosphates

    NASA Technical Reports Server (NTRS)

    Watanabe, S.

    1983-01-01

    An adsorbent which uses as its primary ingredient phosphoric acid salts of zirconium or titanium is presented. Production methods are discussed and several examples are detailed. Measurements of separating characteristics of some gases using the salts are given.

  9. Regenerative adsorbent heat pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  10. Insight into the adsorption of PPCPs by porous adsorbents: Effect of the properties of adsorbents and adsorbates.

    PubMed

    Zhu, Zengyin; Xie, Jiawen; Zhang, Mancheng; Zhou, Qing; Liu, Fuqiang

    2016-07-01

    Adsorption is an efficient method for removal of pharmaceuticals and personal care products (PPCPs). Magnetic resins are efficient adsorbents for water treatment and exhibit potential for PPCP removal. In this study, the magnetic hypercrosslinked resin Q100 was used for adsorption of PPCPs. The adsorption behavior of this resin was compared with those of two activated carbons, namely, Norit and F400D. Norit exhibited the fastest adsorption kinetics, followed by Q100. Norit featured a honeycomb shape and long-range ordered pore channels, which facilitated the diffusion of PPCPs. Moreover, the large average pore size of Q100 reduced diffusion resistance. The adsorbed amounts of 11 PPCPs on the three adsorbents increased with increasing adsorbate hydrophobicity. For Q100, a significant linear correlation was observed between the adsorption performance for PPCPs and hydrophobicity (logD value) of adsorbates (R(2) = 0.8951); as such, PPCPs with high logD values (>1.69) could be efficiently removed. Compared with those of Norit and F400D, the adsorption performance of Q100 was less affected by humic acid because of the dominant hydrophobic interaction. Furthermore, Q100 showed improved regeneration performance, which renders it promising for PPCP removal in practical applications.

  11. Patients with CYP3A4∗1G genetic polymorphism consumed significantly lower amount of sufentanil in general anesthesia during lung resection

    PubMed Central

    Zhang, Huidong; Chen, Minghao; Wang, Xiaodong; Yu, Songyang

    2017-01-01

    Abstract CYP3A4, an isoform of cytochrome P450 enzymes, is responsible for the metabolism of 45% to 60% of currently prescribed drugs. It has been shown that CYP3A4∗1G, a single nucleotide polymorphism (SNP), affects the enzymatic activity of CYP3A4. Sufentanil, a synthetic opioid commonly used for the induction and maintenance of general anesthesia, analgesia, and sedation, is mainly metabolized by CYP3A4. So far, the impact of CYP3A4∗1G on sufentanil metabolism has not been investigated. In the present study, we first determined the frequency of CYP3A4∗1G polymorphism in patients of Chinese Han nationality who underwent lung resection, and then compared the amount of sufentanil used in general anesthesia during the surgical procedure between wild type and mutant patients. DNA sequencing was performed to genotype the CYP3A4∗1G allele in 191 patients. The sufentanil dosages consumed in general anesthesia were recorded and compared between wild-type and mutant patients. The frequency of the CYP3A4∗1G variant allele was 0.202 (77/382). No significant difference was observed in age, body weight, or operation time between wild-type and mutant patients. The amount of sufentanil consumed by patients with the point mutation was significantly lower than that in the wild type group. No significant difference in sufentanil dosages was observed between females and males within wild type or within mutant group. High frequency of CYP3A4∗1G variants was detected in patients of Chinese Han nationality. Significantly lower amount of sufentanil was consumed in mutant patients compared with wild type subjects, likely a result of impaired CYP3A4 activity due to the point mutation. These findings suggest genotyping of CYP3A4 might be of value in providing guidance for the use of sufentanil. PMID:28121959

  12. Enhanced membrane filtration of wood hydrolysates for hemicelluloses recovery by pretreatment with polymeric adsorbents.

    PubMed

    Koivula, Elsi; Kallioinen, Mari; Sainio, Tuomo; Antón, Enrique; Luque, Susana; Mänttäri, Mika

    2013-09-01

    In this study adsorption of foulants from birch and pine/eucalyptus wood hydrolysates on two polymeric adsorbents was studied aiming to reduce the membrane fouling. The effect of the pretreatment of hydrolysate on polyethersulphone membrane performance was studied in dead-end filtration experiments. Adsorption pretreatment improved significantly filtration capacity and decreased membrane fouling. Especially high-molecular weight lignin was efficiently removed. A multistep adsorption pretreatment was found to reduce the amount of adsorbent required. While large adsorbent amount was shown to increase flux in filtration, it was found also to cause significant hemicellulose losses.

  13. Adsorption and trace detection of pharmacologically significant 5-methylthio-1, 3, 4-thiadiazole-2-thiol molecule adsorbed on silver nanocolloids and understanding the role of Albrecht's “A” and Herzberg-Teller contributions in the SERS spectra

    NASA Astrophysics Data System (ADS)

    Chowdhury, Joydeep; Chandra, Subhendu; Ghosh, Manash

    2015-01-01

    The surface enhanced Raman scattering (SERS) spectra of biologically and industrially significant 5-methylthio-1, 3, 4-thiadiazole 2-thiol molecule have been investigated. The SERS spectra at various concentrations of the adsorbate are compared with the Fourier transform Infrared (FTIR) and normal Raman spectra (NRS) of the probe molecule recorded in different environmental conditions. The optimized molecular structures of the most probable thione and the thiol forms of the molecule have been estimated from the density functional theory (DFT) calculations. The vibrational signatures of the molecule have been assigned from the potential energy distributions (PEDs). The detail vibrational analyses reveal that ∼54% of the thione form of the molecule is prevalent in the solid state and its population increases to ∼65% in ACN solvent medium. Concentration dependent SERS, together with the 2-dimensional correlation spectra (2D-COS), corroborate the presence of both the thione and the thiol forms of the molecule even in the surface adsorbed state. The orientations of the thione and the thiol forms of the molecule on the nanocolloidal silver surface have been predicted from the surface selection rule. The selective enhancement of Raman bands in the SERS spectra have been explored from the view of the Albrecht's "A" and Herzberg-Teller (HT) charge transfer (CT) contribution.

  14. Very low amount of TiO2 on N-doped carbon nanotubes significantly improves oxygen reduction activity and stability of supported Pt nanoparticles.

    PubMed

    Zhao, Anqi; Masa, Justus; Xia, Wei

    2015-04-28

    Electrochemical corrosion is a major problem for carbon materials used in electrocatalysis. Highly dispersed TiO2 was deposited on O-functionalized and N-doped carbon nanotubes by chemical vapour deposition to tackle the carbon corrosion problem. Very low Ti loadings of about 1 wt% were applied to minimize the negative influence of TiO2 as a semiconductor on the high conductivity of carbon materials. Both N doping and TiO2 coating facilitate strong metal-support interactions and favour the formation of small Pt particles. N doping improved the intrinsic catalytic activity of the carbon support and enhanced the conductivity due to the removal of surface oxygen groups, while the negative effect of TiO2 on conductivity is counterbalanced by its promoting effect on metal-support interactions leading to enhanced overall catalytic performance. Pt/TiO2/NCNTs showed the highest ORR activity, and significantly outperformed Pt/NCNTs in electrochemical stability tests.

  15. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    SciTech Connect

    Tsouris, Costas; Mayes, Richard T.; Janke, Christopher James; Dai, Sheng; Das, S.; Liao, W. -P.; Kuo, Li-Jung; Wood, Jordana; Gill, Gary; Byers, Maggie Flicker; Schneider, Eric

    2015-09-30

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  16. Adsorbed natural gas storage with activated carbon

    SciTech Connect

    Sun, Jian; Brady, T.A.; Rood, M.J.

    1996-12-31

    Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

  17. Modeling adsorption: Investigating adsorbate and adsorbent properties

    NASA Astrophysics Data System (ADS)

    Webster, Charles Edwin

    1999-12-01

    Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

  18. Titanium-incorporated organic–inorganic hybrid adsorbent for improved CO{sub 2} adsorption performance

    SciTech Connect

    Zhang, Xiaoyun; Qin, Hongyan; Zhang, Sisi; Wu, Wei

    2015-02-15

    Highlights: • Titanium-incorporated organic–inorganic hybrid adsorbent was prepared. • The incorporation of Ti to the adsorbent showed significant effect. • The sorbent shows high CO{sub 2} capture capacity both in pure and diluted CO{sub 2} at RT. • The sorbent exhibits a high recycling stability after 15 cycling runs. - Abstract: The CO{sub 2} adsorption performance of acrylonitrile (AN)–tetraethylenepentamine (TEPA) adduct (hereafter referred to as TN) impregnated adsorbent was greatly enhanced by introduction of Titanium atom into the silica matrix. The adsorbents were characterized by X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} adsorption/desorption, UV–vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy. The adsorption experiments together with the physicochemical characterization demonstrated that these adsorbents containing an optimal amount of Titanium (Ti/Si ≈ 0.1) remarkably reinforced the CO{sub 2} adsorption capacity and recycling stability. The highest CO{sub 2} uptakes reached 4.65 and 1.80 mmol CO{sub 2}/g adsorbent at 25 °C under 90% CO{sub 2} (CO{sub 2}/N{sub 2}, 90:10 V/V) and 1% CO{sub 2} (CO{sub 2}/N{sub 2}, 1:99 V/V) conditions for sample Ti(0.1)-DMS-TN, respectively. Repeated adsorption/desorption cycles revealed that the Ti-incorporated adsorbent showed only a tiny decrease in adsorption capacity (1.778 mmol CO{sub 2}/g adsorbent after 15 cycles, decreased by 0.95%), significantly enhanced the adsorbent recycling stability.

  19. Adsorbed Water Illustration

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Thermal and Electrical Conductivity Probe on NASA's Phoenix Mars Lander detected small and variable amounts of water in the Martian soil.

    In this schematic illustration, water molecules are represented in red and white; soil minerals are represented in green and blue. The water, neither liquid, vapor, nor solid, adheres in very thin films of molecules to the surfaces of soil minerals. The left half illustrates an interpretation of less water being adsorbed onto the soil-particle surface during a period when the tilt, or obliquity, of Mars' rotation axis is small, as it is in the present. The right half illustrates a thicker film of water during a time when the obliquity is greater, as it is during cycles on time scales of hundreds of thousands of years. As the humidity of the atmosphere increases, more water accumulates on mineral surfaces. Thicker films behave increasingly like liquid water.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  20. Enhanced Photovoltaic Properties of Potassium-Adsorbed Titania Nanotubes

    SciTech Connect

    Richter, C.; Jaye, C; Fischer, D; Lewis, L; Willey, R; Menon, L

    2009-01-01

    It is demonstrated that vertically-aligned titania nanotube planar arrays fabricated by electrochemical anodization using standard potassium-containing electrolytes invariably contain a significant amount of surface-adsorbed potassium ions, hitherto undetected, that affect the titania photoelectrochemical or PEC performance. Synchrotron-based near edge X-ray absorption fine structure (NEXAFS) spectroscopy reveals the strong ionic nature of surface potassium-titania bonds that alters the PEC performance over that of pure titania nanotubes through reduction of the external electrical bias needed to produce hydrogen at maximum efficiency. This result implies that the external electrical energy input required per liter of solar hydrogen produced with potassium-adsorbed titania nanotubes may be reduced. Tailoring the potassium content may thus be an alternative means to fine-tune the photoelectrochemical response of TiO2 nanotube-based PEC electrodes.

  1. Molecular Adsorber Coating

    NASA Technical Reports Server (NTRS)

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  2. Adsorbent and adsorbent bed for materials capture and separation processes

    DOEpatents

    Liu, Wei

    2011-01-25

    A method device and material for performing adsorption wherein a fluid mixture is passed through a channel in a structured adsorbent bed having a solid adsorbent comprised of adsorbent particles having a general diameter less than 100 um, loaded in a porous support matrix defining at least one straight flow channel. The adsorbent bed is configured to allow passage of a fluid through said channel and diffusion of a target material into said adsorbent under a pressure gradient driving force. The targeted molecular species in the fluid mixture diffuses across the porous support retaining layer, contacts the adsorbent, and adsorbs on the adsorbent, while the remaining species in the fluid mixture flows out of the channel.

  3. Synthesis of novel aminated cellulose microsphere adsorbent for efficient Cr(VI) removal

    NASA Astrophysics Data System (ADS)

    Yu, Tianlin; Liu, Siqi; Xu, Min; Peng, Jing; Li, Jiuqiang; Zhai, Maolin

    2016-08-01

    A novel aminated cellulose microsphere adsorbent (CVN) was successfully prepared by radiation-induced graft polymerization of vinylbenzyl chloride (VBC) onto cellulose microsphere (CMS), followed by amination. Micro-FTIR, XPS and SEM confirmed the structure of CVN. The adsorption behavior of Cr(VI) onto CVN from solution was well fitted by the pseudo-second order kinetic model. The isothermal adsorption of Cr(VI) was observed at pH 4.68 with adsorption capacity of 129 mg/g in accordance with Langmuir thermal model, and the removal of Cr(VI) from solution could be 91% at a low amount (20 mg) of adsorbent. The best pH for adsorption of Cr(VI) was nearly 3.08, and with the increasing of temperature, the adsorption capacity of Cr(VI) increased. XPS analysis confirmed the adsorption mechanism of Cr(VI) was ion-exchange mechanism, while common co-ions such as Na+, Mg2+, Cu2+, Ca2+, Zn2+, Ni2+, Cl-, NO3- has no significant effect on the adsorption capacity of Cr(VI), and the Cr(VI) removal of 80% still could be obtained compared with that of fresh CVN adsorbent. Finally, spent CVN could be regenerated under 2 mol/L NaCl. The work indicated that aminated cellulose adsorbent could be prepared successfully by radiation-induced grafting and amination and CVN is a promising bio-adsorbent in the removing Cr(VI) from waste water.

  4. Mercury removal from solution by superconducting magnetic separation with nanostructured magnetic adsorbents

    NASA Astrophysics Data System (ADS)

    Okamoto, T.; Tachibana, S.; Miura, O.; Takeuchi, M.

    2011-11-01

    Recently, mercury Hg concentration in human blood increases due to expanding the global mercury contamination. Excess mercury bioaccumulation poses a significant health risk. In order to decrease mercury concentration in the environment and human blood, we have developed two different kinds of nanostructured magnetic adsorbents for mercury to apply them to superconducting magnetic separation instead of conventional filtration. One is magnetic beads (MBs) which have nanosize magnetite particles in the core and a lot of SH radicals on the surface to adsorb Hg ions effectively. MBs were developed mainly to remove mercury from human blood. The maximum amount of the adsorption for MBs is 6.3 mg/g in the solution in less than a minute. Dithiothreitol can easily remove mercury adsorbed to MBs, hence MBs can be reusable. The other is nanostructured magnetic activated carbon (MAC) which is activated carbon with mesopores and nanosize magnetite. The maximum amount of the adsorption for MAC is 38.3 mg/g in the solution. By heat-treatment mercury can be easily removed from MAC. We have studied superconducting magnetic separation using each adsorbent for mercury removal from solution.

  5. Adsorbent materials from paper industry waste materials and their use in Cu(II) removal from water.

    PubMed

    Méndez, A; Barriga, S; Fidalgo, J M; Gascó, G

    2009-06-15

    This paper deals with the removal of Cu(2+) from water using adsorbent materials prepared from paper industry waste materials (one de-inking paper sludge and other sludge from virgin pulp mill). Experimental results showed that de-inking paper sludge leads to mesoporous materials (V(mic)/V(T)=0.13 and 0.14), whereas the sludge from virgin pulp mill produces high microporous adsorbents (V(mic)/V(T)=0.39 and 0.41). Adsorbent materials were then used for Cu(2+) removal from water at acid pH. During water treatment, heavy metals lixiviation from adsorbent materials was not produced. However, important Ca and Mg leaching was observed. Final pH significantly increases after treatment of water with adsorbent materials probably due to their elevated CaCO(3) content. In general, highest Cu(2+) removal was obtained using adsorbent materials from de-inking paper sludge. This result could be due to their higher content in oxygenated surface groups, high average pore diameter, elevated superficial charge density, high CaCO(3) amount and high Ca and Mg exchange content.

  6. Effect of Polarity of Activated Carbon Surface, Solvent and Adsorbate on Adsorption of Aromatic Compounds from Liquid Phase.

    PubMed

    Goto, Tatsuru; Amano, Yoshimasa; Machida, Motoi; Imazeki, Fumio

    2015-01-01

    In this study, introduction of acidic functional groups onto a carbon surface and their removal were carried out through two oxidation methods and outgassing to investigate the adsorption mechanism of aromatic compounds which have different polarity (benzene and nitrobenzene). Adsorption experiments for these aromatics in aqueous solution and n-hexane solution were conducted in order to obtain the adsorption isotherms for commercial activated carbon (BAC) as a starting material, its two types of oxidized BAC samples (OXs), and their outgassed samples at 900 °C (OGs). Adsorption and desorption kinetics of nitrobenzene for the BAC, OXs and OGs in aqueous solution were also examined. The results showed that the adsorption of benzene molecules was significantly hindered by abundant acidic functional groups in aqueous solution, whereas the adsorbed amount of nitrobenzene on OXs gradually increased as the solution concentration increased, indicating that nitrobenzene can adsorb favourably on a hydrophilic surface due to its high dipole moment, in contrast to benzene. In n-hexane solution, it was difficult for benzene to adsorb on any sample owing to the high affinity between benzene and n-hexane solvent. On the other hand, adsorbed amounts of nitrobenzene on OXs were larger than those of OGs in n-hexane solution, implying that nitrobenzene can adsorb two adsorption sites, graphene layers and surface acidic functional groups. The observed adsorption and desorption rate constants of nitrobenzene on the OXs were lower than those on the BAC due to disturbance of diffusion by the acidic functional groups.

  7. Radiation synthesis of a new amidoximated UHMWPE fibrous adsorbent with high adsorption selectivity for uranium over vanadium in simulated seawater

    NASA Astrophysics Data System (ADS)

    Gao, Qianhong; Hu, Jiangtao; Li, Rong; Xing, Zhe; Xu, Lu; Wang, Mouhua; Guo, Xiaojing; Wu, Guozhong

    2016-05-01

    A new kind of highly efficient adsorbent material has been fabricated in this study for the purpose of extracting uranium from seawater. Ultra-high molecular weight polyethylene (UHMWPE) fiber was used as a trunk material for the adsorbent, which was prepared by a series of modification reactions, as follows: (1) grafting of glycidyl methacrylate (GMA) and methyl acrylate (MA) onto UHMWPE fibers via 60Co γ-ray pre-irradiation; (2) aminolyzation of UHMWPE fiber by the ring-opening reaction between of epoxy groups PGMA and ethylene diamine (EDA); (3) Michael addition of amino groups with acrylonitrile (AN) to yield nitrile groups; (4) amidoximation of the attached nitrile moieties by hydroxylamine in dimethyl sulfoxide-water mixture. Modified UHMWPE fibers were characterized by means of attenuated total reflectance-Fourier transformed infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) to confirm the attachment of amidoxime (AO) groups onto the UHMWPE fibers. The results of X-ray diffraction (XRD) and single fiber tensile strength verified that the modified UHMWPE fiber retained excellent mechanical properties at a low absorbed radiation dose. The adsorption performance of the UHMWPE fibrous adsorbent was evaluated by subjecting it to an adsorption test in simulated seawater using a continuous-flow mode. The amount of uranium adsorbed by this AO-based UHMWPE fibrous adsorbent was 1.97 mg-U/g after 42 days. This new adsorbent also showed high selectivity for the uranyl ion, and its selectivity for metal ions was found to decrease in the following order: U>Cu>Fe>Ca>Mg>Ni>Zn>Pb>V>Co. The adsorption selectivity for uranium is significantly higher than that for vanadium. In addition, preparation of this modified adsorbent consumes much smaller amounts of the toxic acrylonitrile monomer than the conventional preparation methods of AO-based polyethylene fibers.

  8. Properties of competitively adsorbed BSA and fibrinogen from their mixture on mixed and hybrid surfaces

    NASA Astrophysics Data System (ADS)

    Pandey, Lalit M.; Pattanayek, Sudip K.

    2013-01-01

    We have studied the adsorption of BSA and fibrinogen from their mixture onto surfaces with mixed self-assembled monolayer (SAM) of amine and octyl (ratio 1:1) and hybrid SAM. The properties of adsorbed proteins obtained from individual protein solution differ considerably from the properties of the adsorbed proteins obtained from mixture of proteins at same total concentration. The adsorbed amount of proteins is lesser and the adsorbed protein is more elastic if it is adsorbing from mixture of proteins. It is found that with increasing total protein concentration, adsorbed amount increases and elasticity of the adsorbed proteins decreases. The apparent displacements of BSA with Fb are observed on the graphs of change in frequency with time, which are obtained from quartz crystal microbalance.

  9. Contact time optimization of two-stage batch adsorber design using second-order kinetic model for the adsorption of phosphate onto alunite.

    PubMed

    Ozacar, Mahmut

    2006-09-01

    The adsorption of phosphate onto alunite in a batch adsorber has been studied. Four kinetic models including pseudo first- and second-order equation, intraparticle diffusion equation and the Elovich equation were selected to follow the adsorption process. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was shown that the adsorption of phosphate onto alunite could be described by the pseudo second-order equation. Adsorption of phosphate onto alunite followed the Langmuir isotherm. A model has been used for the design of a two-stage batch adsorber based on pseudo second-order adsorption kinetics. The model has been optimized with respect to operating time in order to minimize total operating time to achieve a specified amount of phosphate removal using a fixed mass of adsorbent. The results of two-stage batch adsorber design studies showed that the required times for specified amounts of phosphate removal significantly decreased. It is particularly suitable for low-cost adsorbents/adsorption systems when minimising operating time is a major operational and design criterion, such as, for highly congested industrial sites in which significant volume of effluent need to be treated in the minimum amount of time.

  10. Mercury adsorption properties of sulfur-impregnated adsorbents

    USGS Publications Warehouse

    Hsi, N.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

    2002-01-01

    Carbonaceous and noncarbonaceous adsorbents were impregnated with elemental sulfur to evaluate the chemical and physical properties of the adsorbents and their equilibrium mercury adsorption capacities. Simulated coal combustion flue gas conditions were used to determine the equilibrium adsorption capacities for Hg0 and HgCl2 gases to better understand how to remove mercury from gas streams generated by coal-fired utility power plants. Sulfur was deposited onto the adsorbents by monolayer surface deposition or volume pore filling. Sulfur impregnation increased the total sulfur content and decreased the total and micropore surface areas and pore volumes for all of the adsorbents tested. Adsorbents with sufficient amounts of active adsorption sites and sufficient microporous structure had mercury adsorption capacities up to 4,509 ??g Hg/g adsorbent. Elemental sulfur, organic sulfur, and sulfate were formed on the adsorbents during sulfur impregnation. Correlations were established with R2>0.92 between the equilibrium Hg0/HgCl2 adsorption capacities and the mass concentrations of elemental and organic sulfur. This result indicates that elemental and organic sulfur are important active adsorption sites for Hg0 and HgCl2.

  11. Surface properties of mesoporous carbon-silica gel adsorbents

    SciTech Connect

    Leboda, R.; Turov, V.V.; Charmas, B.; Skubiszewska-Zieba, J.; Gun'ko, V.M.

    2000-03-01

    Carbon/silica (carbosil) samples prepared utilizing mesoporous silica gel (Si-60) modified by methylene chloride pyrolysis were studied by nitrogen adsorption, quasi-isothermal thermogravimetry, p-nitrophenol adsorption from aqueous solution, and {sup 1}H NMR methods. The structural characteristics and other properties of carbosils depend markedly on the synthetic conditions and the amount of carbon deposited. The changes in the pore size distribution with increasing carbon concentration suggest grafting of carbon mainly in pores, leading to diminution of the mesopore radii. However, heating pure silica gel at the pyrolysis temperature of 550 C leads to an increase in the pore radii. The quasi-isothermal thermogravimetry and {sup 1}H NMR spectroscopy methods used to investigate the water layers on carbosils showed a significant capability of carbosils to adsorb water despite a relatively large content of the hydrophobic carbon deposit, which represents a nonuniform layer incompletely covering the oxide surface.

  12. Solvent cleanup using base-treated silica gel solid adsorbent

    SciTech Connect

    Tallent, O.K.; Mailen, J.C.; Pannell, K.D.

    1984-06-01

    A solvent cleanup method using silica gel columns treated with either sodium hydroxide (NaOH) or lithium hydroxide (LiOH) has been investigated. Its effectiveness compares favorably with that of traditional wash methods. After treatment with NaOH solution, the gels adsorb HNO/sub 3/, dibutyl phosphate (DBP), UO/sub 2//sup 2 +/, Pu/sup 4 +/, various metal-ion fission products, and other species from the solvent. Adsorption mechanisms include neutralization, hydrolysis, polymerization, and precipitation, depending on the species adsorbed. Sodium dibutyl phosphate, which partially distributes to the solvent from the gels, can be stripped with water; the stripping coefficient ranges from 280 to 540. Adsorption rates are diffusion controlled such that temperature effects are relatively small. Recycle of the gels is achieved either by an aqueous elution and recycle sequence or by a thermal treatment method, which may be preferable. Potential advantages of this solvent cleanup method are that (1) some operational problems are avoided and (2) the amount of NaNO/sub 3/ waste generated per metric ton of nuclear fuel reprocessed would be reduced significantly. 19 references, 6 figures, 12 tables.

  13. Remediation of AMD using industrial waste adsorbents

    NASA Astrophysics Data System (ADS)

    Mohammed, Nuur Hani Bte; Yaacob, Wan Zuhairi Wan

    2016-11-01

    The study investigates the characteristic of industrial waste as adsorbents and its potential as heavy metals absorbents in AMD samples. The AMD sample was collected from active mine pond and the pH was measured in situ. The metal contents were analyzed by ICP-MS. The AMD water was very acidic (pH< 3.5), and the average heavy metals content in AMD were high especially in Fe (822.029 mg/l). Fly ash was found to be the most effective absorbent material containing high percentage of CaO (57.24%) and SiO2 (13.88%), followed by ladle furnace slag containing of high amount of CaO (51.52%) and Al2O3 (21.23%), while biomass ash consists of SiO2 (43.07%) and CaO (12.97%). Tank analysis display a huge changes due to pH value change from acidity to nearly neutral phases. After 50 days, fly ash remediation successfully increase the AMD pH values from pH 2.57-7.09, while slag change from acidity to nearly alkaline phase from pH 2.60-7.3 and biomass has change to pH 2.54-6.8. Fly ash has successfully remove Fe, Mn, Cu, and Ni. Meanwhile, slag sample displays as an effective adsorbent to adsorb more Pb and Cd in acid mine drainage.

  14. MTBE adsorption on alternative adsorbents and packed bed adsorber performance.

    PubMed

    Rossner, Alfred; Knappe, Detlef R U

    2008-04-01

    Widespread use of the fuel additive methyl tertiary-butyl ether (MTBE) has led to frequent MTBE detections in North American and European drinking water sources. The overall objective of this research was to evaluate the effectiveness of a silicalite zeolite, a carbonaceous resin, and a coconut-shell-based granular activated carbon (GAC) for the removal of MTBE from water. Isotherm and short bed adsorber tests were conducted in ultrapure water and river water to obtain parameters describing MTBE adsorption equilibria and kinetics and to quantify the effect of natural organic matter (NOM) on MTBE adsorption. Both the silicalite zeolite and the carbonaceous resin exhibited larger MTBE adsorption uptakes than the tested GAC. Surface diffusion coefficients describing intraparticle MTBE mass transfer rates were largest for the GAC and smallest for the carbonaceous resin. Pilot tests were conducted to verify MTBE breakthrough curve predictions obtained with the homogeneous surface diffusion model and to evaluate the effect of NOM preloading on packed bed adsorber performance. Results showed that GAC was the most cost-competitive adsorbent when considering adsorbent usage rate only; however, the useful life of an adsorber containing silicalite zeolite was predicted to be approximately 5-6 times longer than that of an equally sized adsorber containing GAC. Pilot column results also showed that NOM preloading did not impair the MTBE removal efficiency of the silicalite zeolite. Thus, it may be possible to regenerate spent silicalite with less energy-intensive methods than those required to regenerate GAC.

  15. Development and testing of molecular adsorber coatings

    NASA Astrophysics Data System (ADS)

    Abraham, Nithin S.; Hasegawa, Mark M.; Straka, Sharon A.

    2012-10-01

    The effect of on-orbit molecular contamination has the potential to degrade the performance of spaceflight hardware and diminish the lifetime of the spacecraft. For example, sensitive surfaces, such as optical surfaces, electronics, detectors, and thermal control surfaces, are vulnerable to the damaging effects of contamination from outgassed materials. The current solution to protect these surfaces is through the use of zeolite coated ceramic adsorber pucks. However, these pucks and its additional complex mounting hardware requirements result in several disadvantages, such as size, weight, and cost related concerns, that impact the spacecraft design and the integration and test schedule. As a result, a new innovative molecular adsorber coating was developed as a sprayable alternative to mitigate the risk of on-orbit molecular contamination. In this study, the formulation for molecular adsorber coatings was optimized using various binders, pigment treatment methods, binder to pigment ratios, thicknesses, and spray application techniques. The formulas that passed coating adhesion and vacuum thermal cycling were further tested for its adsorptive capacity. Accelerated molecular capacitance tests were performed in an innovatively designed multi-unit system containing idealized contaminant sources. This novel system significantly increased the productivity of the testing phase for the various formulations that were developed. Work performed during the development and testing phases has demonstrated successful application of molecular adsorber coatings onto metallic substrates, as well as, very promising results for the adhesion performance and the molecular capacitance of the coating. Continued testing will assist in the qualification of molecular adsorber coatings for use on future contamination sensitive spaceflight missions.

  16. Development and Testing of Molecular Adsorber Coatings

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin; Hasegawa, Mark; Straka, Sharon

    2012-01-01

    The effect of on-orbit molecular contamination has the potential to degrade the performance of spaceflight hardware and diminish the lifetime of the spacecraft. For example, sensitive surfaces, such as optical surfaces, electronics, detectors, and thermal control surfaces, are vulnerable to the damaging effects of contamination from outgassed materials. The current solution to protect these surfaces is through the use of zeolite coated ceramic adsorber pucks. However, these pucks and its additional complex mounting hardware requirements result in several disadvantages, such as size, weight, and cost related concerns, that impact the spacecraft design and the integration and test schedule. As a result, a new innovative molecular adsorber coating was developed as a sprayable alternative to mitigate the risk of on-orbit molecular contamination. In this study, the formulation for molecular adsorber coatings was optimized using various binders, pigment treatment methods, binder to pigment ratios, thicknesses, and spray application techniques. The formulations that passed coating adhesion and vacuum thermal cycling tests were further tested for its adsorptive capacity. Accelerated molecular capacitance tests were performed in an innovatively designed multi-unit system containing idealized contaminant sources. This novel system significantly increased the productivity of the testing phase for the various formulations that were developed. Work performed during the development and testing phases has demonstrated successful application of molecular adsorber coatings onto metallic substrates, as well as, very promising results for the adhesion performance and the molecular capacitance of the coating. Continued testing will assist in the qualification of molecular adsorber coatings for use on future contamination sensitive spaceflight missions.

  17. Cryogenic adsorber design in a helium refrigeration system

    NASA Astrophysics Data System (ADS)

    Hu, Zhongjun; Zhang, Ning; Li, Zhengyu; Li, Q.

    2012-06-01

    The cryogenic adsorber is specially designed to eliminate impurities in gaseous helium such as O2, and N2 which is normally difficult to remove, based on the reversible cryotrapping of impurities on an activated carbon bed. The coconut shell activated carbon is adopted because of its developed micropore structure and specific surface area. This activated carbon adsorption is mostly determined by the micropore structure, and the adsorption rate of impurities is inversely proportional to the square of the particle sizes. The active carbon absorber's maximum permissible flow velocity is 0.25 m/s. When the gas flow velocity increases, the adsorption diffusion rate of the adsorbent is reduced, because an increase in the magnitude of the velocity resulted in a reduced amount of heat transfer to a unit volume of impure gas. According to the numerical simulation of N2 adsorption dynamics, the appropriate void tower link speed and the saturated adsorption capacity are determined. Then the diameter and height of the adsorber are designed. The mass transfer length should be taken into account in the adsorber height design. The pressure decrease is also calculated. The important factors that influence the adsorber pressure decrease are the void tower speed, the adsorbed layer height, and the active carbon particle shape and size.

  18. Evaluation of a cesium adsorbent grafted with ammonium 12-molybdophosphate

    NASA Astrophysics Data System (ADS)

    Shibata, Takuya; Seko, Noriaki; Amada, Haruyo; Kasai, Noboru; Saiki, Seiichi; Hoshina, Hiroyuki; Ueki, Yuji

    2016-02-01

    A fibrous cesium (Cs) adsorbent was developed using radiation-induced graft polymerization with a cross-linked structure containing a highly stable adsorption ligand. The ligand, ammonium 12-molybdophosphate (AMP), was successfully introduced onto the fibrous polyethylene trunk material. The resulting Cs adsorbent contained 36% nonwoven fabric polyethylene (NFPE), 1% AMP, 2% triallyl isocyanurate (TAIC) and 61% glycidyl methacrylate (GMA). The adsorbent's Cs adsorption capacity was evaluated using batch and column tests. It was determined that the adsorbent could be used in a wide pH range. The amount of desorbed molybdenum, which can be used as an estimate for AMP stability on the Cs adsorbent, was minimized at the standard drinking water pH range of 5.8-8.6. Based from the inspection on the adherence of these results to the requirements set forth by the Food Sanitation Act by a third party organization, it can be concluded that the developed Cs adsorbent can be safely utilized for drinking water.

  19. Nanoclay-Based Solid-Amine Adsorbents for Carbon Dioxide Capture

    NASA Astrophysics Data System (ADS)

    Roth, Elliot A.

    The objective of this research was to develop an efficient, low cost, recyclable solid sorbent for carbon dioxide adsorption from large point sources, such as coal-fired power plants. The current commercial way to adsorb CO 2 is to use a liquid amine or ammonia process. These processes are used in industry in the "sweetening" of natural gas, but liquid based technologies are not economically viable in the adsorption of CO2 from power plants due to the extremely large volume of CO2 and the inherent high regeneration costs of cycling the sorbent. Therefore, one of the main objectives of this research was to develop a novel sorbent that can be cycled and uses very little energy for regeneration. The sorbent developed here is composed of a nanoclay (montmorillonite), commonly used in the production of polymer nanocomposites, grafted with commercially available amines. (3-aminopropyl) trimethoxysilane (APTMS) was chemically grafted to the edge hydroxyl groups of the clay. While another amine, polyethylenimine (PEI), was attached to the surface of the clay by electrostatic interactions. To confirm the attachment of amines to the clay, the samples were characterized using FTIR and the corresponding peaks for amines were observed. The amount of amine loaded onto the support was determined by TGA techniques. The treated clay was initially analyzed for CO2 adsorption in a pure CO 2 stream. The adsorption temperatures that had the highest adsorption capacity were determined to be between 75°C and 100°C for all of the samples tested at atmospheric pressure. The maximum CO2 adsorption capacity observed was with nanoclay treated with both APTMS and PEI at 85°C. In a more realistic flue gas of 10% CO2 and 90% N2, the adsorbents had essentially the same overall CO2 adsorption capacity indicating that the presence of nitrogen did not hinder the adsorption of CO2. Adsorption studies in pure CO2 at room temperature under pressure from 40-300 PSI were also conducted. The average

  20. Oil palm biomass as an adsorbent for heavy metals.

    PubMed

    Vakili, Mohammadtaghi; Rafatullah, Mohd; Ibrahim, Mahamad Hakimi; Abdullah, Ahmad Zuhairi; Salamatinia, Babak; Gholami, Zahra

    2014-01-01

    Many industries discharge untreated wastewater into the environment. Heavy metals from many industrial processes end up as hazardous pollutants of wastewaters.Heavy metal pollution has increased in recent decades and there is a growing concern for the public health risk they may pose. To remove heavy metal ions from polluted waste streams, adsorption processes are among the most common and effective treatment methods. The adsorbents that are used to remove heavy metal ions from aqueous media have both advantages and disadvantages. Cost and effectiveness are two of the most prominent criteria for choosing adsorbents. Because cost is so important, great effort has been extended to study and find effective lower cost adsorbents.One class of adsorbents that is gaining considerable attention is agricultural wastes. Among many alternatives, palm oil biomasses have shown promise as effective adsorbents for removing heavy metals from wastewater. The palm oil industry has rapidly expanded in recent years, and a large amount of palm oil biomass is available. This biomass is a low-cost agricultural waste that exhibits, either in its raw form or after being processed, the potential for eliminating heavy metal ions from wastewater. In this article, we provide background information on oil palm biomass and describe studies that indicate its potential as an alternative adsorbent for removing heavy metal ions from wastewater. From having reviewed the cogent literature on this topic we are encouraged that low-cost oil-palm-related adsorbents have already demonstrated outstanding removal capabilities for various pollutants.Because cost is so important to those who choose to clean waste streams by using adsorbents, the use of cheap sources of unconventional adsorbents is increasingly being investigated. An adsorbent is considered to be inexpensive when it is readily available, is environmentally friendly, is cost-effective and be effectively used in economical processes. The

  1. Rotary adsorbers for continuous bulk separations

    DOEpatents

    Baker, Frederick S [Oak Ridge, TN

    2011-11-08

    A rotary adsorber for continuous bulk separations is disclosed. The rotary adsorber includes an adsorption zone in fluid communication with an influent adsorption fluid stream, and a desorption zone in fluid communication with a desorption fluid stream. The fluid streams may be gas streams or liquid streams. The rotary adsorber includes one or more adsorption blocks including adsorbent structure(s). The adsorbent structure adsorbs the target species that is to be separated from the influent fluid stream. The apparatus includes a rotary wheel for moving each adsorption block through the adsorption zone and the desorption zone. A desorption circuit passes an electrical current through the adsorbent structure in the desorption zone to desorb the species from the adsorbent structure. The adsorbent structure may include porous activated carbon fibers aligned with their longitudinal axis essentially parallel to the flow direction of the desorption fluid stream. The adsorbent structure may be an inherently electrically-conductive honeycomb structure.

  2. Uremic toxins and oral adsorbents.

    PubMed

    Goto, Shunsuke; Yoshiya, Kunihiko; Kita, Tomoyuki; Fujii, Hideki; Fukagawa, Masafumi

    2011-04-01

    Uremic toxins are associated with various disorders in patients with end-stage renal disease and it is difficult to remove some of these toxins by dialysis. Since some uremic toxins are generated by bacterial metabolites in the colon, oral adsorbents that interfere with the absorption of uremic toxins or their precursors are believed to prevent their accumulation in the body. AST-120 adsorbs various uremic retention solutes in the gastrointestinal system and has potential for providing clinical benefit. Sevelamer hydrochloride binds some harmful compounds in addition to phosphate and seems to have pleiotropic effects that include lowering serum LDL cholesterol levels and reduction of inflammation. The effect of sevelamer hydrochloride on indoxyl sulfate and p-cresol has been shown in an in vitro study; however, in vivo studies in mice or humans did not demonstrate this effect on protein-binding uremic toxins. Oral adsorbents are thus one of the important modalities in the treatment of uremic syndrome.

  3. Powder-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2016-05-03

    A powder-based adsorbent and a related method of manufacture are provided. The powder-based adsorbent includes polymer powder with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the powder-based adsorbent includes irradiating polymer powder, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Powder-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  4. Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2015-06-02

    Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  5. Selection and evaluation of adsorbents for the removal of anionic surfactants from laundry rinsing water.

    PubMed

    Schouten, Natasja; van der Ham, Louis G J; Euverink, Gert-Jan W; de Haan, André B

    2007-10-01

    Low-cost adsorbents were tested to remove anionic surfactants from laundry rinsing water to allow re-use of water. Adsorbents were selected corresponding to the different surfactant adsorption mechanisms. Equilibrium adsorption studies of linear alkyl benzene sulfonate (LAS) show that ionic interaction results in a high maximum adsorption capacity on positively charged adsorbents of 0.6-1.7 gLAS/g. Non-ionic interactions, such as hydrophobic interactions of LAS with non-ionic resins or activated carbons, result in a lower adsorption capacity of 0.02-0.6 gLAS/g. Negatively charged materials, such as cation exchange resins or bentonite clay, have negligible adsorption capacities for LAS. Similar results are obtained for alpha olefin sulfonate (AOS). Cost comparison of different adsorbents shows that an inorganic anion exchange material (layered double hydroxide) and activated carbons are the most cost-effective materials in terms of the amount of surfactant adsorbed per dollar worth of adsorbent.

  6. Conformational changes of adsorbed proteins

    NASA Astrophysics Data System (ADS)

    Allen, Scott

    2005-03-01

    The adsorption of bovine serum albumin (BSA) and pepsin to gold surfaces has been studied using surface plasmon resonance (SPR). Proteins are adsorbed from solution onto a gold surface and changes in the conformation of the adsorbed proteins are induced by changing the buffer solution. We selected pH and ionic strength values for the buffer solutions that are known from our circular dichroism measurements to cause conformational changes of the proteins in bulk solution. We find that for both BSA and pepsin the changes in conformation are impeded by the interaction of the protein with the gold surface.

  7. Synergistic desalination of potash brine-impacted groundwater using a dual adsorbent.

    PubMed

    Gibb, Nick P; Dynes, James J; Chang, Wonjae

    2017-03-22

    The impact of saline mining effluent has been a significant environmental concern. Natural and modified clay-mineral adsorbents have been receiving increasing attention for salinity reduction of brine-impacted water, especially for natural resource extraction sites and surrounding environments. In this study, a dual-adsorbent treatment based on the sequential application of calcined layered double hydroxide (CLDH) and acid-treated zeolite was developed, evaluated and characterized for the desalination of potash brine-impacted groundwater. Potash brine produced by conventional potash mining in Saskatchewan (Canada) contains a large amount of Na(+), K(+) and Cl(-). The CLDH and acid-treated clinoptilolite zeolites were combined to sequentially remove Cl(-) and Na(+). A series of batch adsorption experiments were conducted for synthetic saline water and potash brine-spiked groundwater using various combinations of adsorbents: natural zeolites (NZ) or acid-treated zeolites (AZ) with or without the CLDH pretreatment. The experiment revealed that the Na(+) removal percentage was synergistically increased by the dechlorination pretreatment using CLDH, and further improved by AZ. The CLDH-AZ dual adsorbent achieved a Langmuir Na(+) adsorption capacity of 24.4mg/g, a significant improvement over conventional approaches to zeolite-based desalination. Using the brine-impacted groundwater with a high sodium adsorption ratio (SAR) of 13.3±0.1, the CLDH-AZ dual adsorbent decreased the concentrations of Na(+), K(+), and Cl(-) by 87, 97, and 87%, respectively (below drinking water standards). It also exhibited the additional advantages of neutralizing the effluent pH and decreasing the hardness, SAR, and total dissolved sulfur concentration. This study addresses the removal mechanisms, which are associated with the structural memory effect, dealumination, protonic exchanges, and zeolite porosity changes. Synchrotron-based scanning transmission X-ray microscopy analyses provided

  8. A Reliable Hybrid Adsorbent for Efficient Radioactive Cesium Accumulation from Contaminated Wastewater

    PubMed Central

    Awual, Md. Rabiul; Yaita, Tsuyoshi; Miyazaki, Yuji; Matsumura, Daiju; Shiwaku, Hideaki; Taguchi, Tomitsugu

    2016-01-01

    Cesium (Cs) removal from nuclear liquid wastewater has become an emerging issue for safeguarding public health after the accident at the Fukushima Daiichi Nuclear Power Plant. A novel macrocyclic ligand of o-benzo-p-xylyl-22-crown-6-ether (OBPX22C6) was developed and successfully immobilized onto mesoporous silica for the preparation of hybrid adsorbent. The benzene ring π electron is the part of crown ether of OBPX22C6 for easy orientation of the macrocyclic compound for making the π electron donation with Cs complexation. The potential and feasibility of the hybrid adsorbent as being Cs selective was evaluated in terms of sensitivity, selectivity and reusability. The results clarified that the Cs removal process was rapid and reached saturation within a short time. Considering the effect of competitive ions, sodium (Na) did not markedly affect the Cs adsorption whereas potassium (K) was slightly affected due to the similar ionic radii. However, the oxygen in long ethylene glycol chain in OBPX22C6 was expected to show strong coordination, including Cs-π interaction with Cs even in the presence of the high amount of K and Na. Due to its high selectivity and reusability, significant volume reduction is expected as this promising hybrid adsorbent is used for Cs removal in Fukushima wastewater. PMID:26818070

  9. A Reliable Hybrid Adsorbent for Efficient Radioactive Cesium Accumulation from Contaminated Wastewater.

    PubMed

    Awual, Md Rabiul; Yaita, Tsuyoshi; Miyazaki, Yuji; Matsumura, Daiju; Shiwaku, Hideaki; Taguchi, Tomitsugu

    2016-01-28

    Cesium (Cs) removal from nuclear liquid wastewater has become an emerging issue for safeguarding public health after the accident at the Fukushima Daiichi Nuclear Power Plant. A novel macrocyclic ligand of o-benzo-p-xylyl-22-crown-6-ether (OBPX22C6) was developed and successfully immobilized onto mesoporous silica for the preparation of hybrid adsorbent. The benzene ring π electron is the part of crown ether of OBPX22C6 for easy orientation of the macrocyclic compound for making the π electron donation with Cs complexation. The potential and feasibility of the hybrid adsorbent as being Cs selective was evaluated in terms of sensitivity, selectivity and reusability. The results clarified that the Cs removal process was rapid and reached saturation within a short time. Considering the effect of competitive ions, sodium (Na) did not markedly affect the Cs adsorption whereas potassium (K) was slightly affected due to the similar ionic radii. However, the oxygen in long ethylene glycol chain in OBPX22C6 was expected to show strong coordination, including Cs-π interaction with Cs even in the presence of the high amount of K and Na. Due to its high selectivity and reusability, significant volume reduction is expected as this promising hybrid adsorbent is used for Cs removal in Fukushima wastewater.

  10. A Reliable Hybrid Adsorbent for Efficient Radioactive Cesium Accumulation from Contaminated Wastewater

    NASA Astrophysics Data System (ADS)

    Awual, Md. Rabiul; Yaita, Tsuyoshi; Miyazaki, Yuji; Matsumura, Daiju; Shiwaku, Hideaki; Taguchi, Tomitsugu

    2016-01-01

    Cesium (Cs) removal from nuclear liquid wastewater has become an emerging issue for safeguarding public health after the accident at the Fukushima Daiichi Nuclear Power Plant. A novel macrocyclic ligand of o-benzo-p-xylyl-22-crown-6-ether (OBPX22C6) was developed and successfully immobilized onto mesoporous silica for the preparation of hybrid adsorbent. The benzene ring π electron is the part of crown ether of OBPX22C6 for easy orientation of the macrocyclic compound for making the π electron donation with Cs complexation. The potential and feasibility of the hybrid adsorbent as being Cs selective was evaluated in terms of sensitivity, selectivity and reusability. The results clarified that the Cs removal process was rapid and reached saturation within a short time. Considering the effect of competitive ions, sodium (Na) did not markedly affect the Cs adsorption whereas potassium (K) was slightly affected due to the similar ionic radii. However, the oxygen in long ethylene glycol chain in OBPX22C6 was expected to show strong coordination, including Cs-π interaction with Cs even in the presence of the high amount of K and Na. Due to its high selectivity and reusability, significant volume reduction is expected as this promising hybrid adsorbent is used for Cs removal in Fukushima wastewater.

  11. Use of potassium dihydrogen phosphate and sawdust as adsorbents of ammoniacal nitrogen in aerobic composting process.

    PubMed

    Hu, Tian-Jue; Zeng, Guang-Ming; Huang, Dan-Lian; Yu, Hong-Yan; Jiang, Xiao-Yun; Dai, Fang; Huang, Guo-He

    2007-03-22

    Three kinds of adsorbents-potassium dihydrogen phosphate, sawdust and mixture of potassium dihydrogen phosphate and sawdust were added respectively into composting to investigate their adsorption effect on ammonia. The experimental results showed that all the adsorbents could restrain ammonia volatilizing, with the sorption of potassium dihydrogen phosphate adsorbents being the best of all, the sorption of mixture adsorbent with potassium dihydrogen phosphate and sawdust being the second and the sorption of sawdust adsorbent being the last. Therefore, the total nitrogen loss ratios respectively reduced from 38% to 13%, 15% and 21% after adding these three kinds of adsorbents into composting. However, potassium dihydrogen phosphate produced negative influence on composting properties as its supplemented amount exceeded a quantity basis equivalent to 18% of total nitrogen in the composting, for example: pH value had been lessened, microorganism activity reduced, which finally resulted in the reduction of biodegradation ratio of organic matter. But it did not result in these problems when using the mixture of potassium dihydrogen phosphate and sawdust as adsorbent, in which the amount of potassium dihydrogen phosphate was under a quantity basis equivalent to 6% of total nitrogen in the composting. Moreover, the mixture adsorbent produced better adsorption effect on ammonia, and raised biodegradation ratio of organic matter from 26% to 33%.

  12. Efficiency of sepiolite in broilers diet as uranium adsorbent.

    PubMed

    Mitrović, Branislava M; Jovanović, Milijan; Lazarević-Macanović, Mirjana; Janaćković, Djordje; Krstić, Nikola; Stojanović, Mirjana; Mirilović, Milorad

    2015-05-01

    The use of phosphate mineral products in animal nutrition, as a major source of phosphor and calcium, can lead to uranium entering the food chain. The aim of the present study was to determine the protective effect of natural sepiolite and sepiolite treated with acid for broilers after oral intake of uranium. The broilers were contaminated for 7 days with 25 mg/uranyl nitrate per day. Two different adsorbents (natural sepiolite and sepiolite treated with acid) were given via gastric tube immediately after the oral administration of uranium. Natural sepiolite reduced uranium distribution by 57% in kidney, 80% in liver, 42% in brain, and 56% in muscle. A lower protective effect was observed after the administration of sepiolite treated with acid, resulting in significant damage of intestinal villi in the form of shortening, fragmentation, and necrosis, and histopathological lesions on kidney in the form of edema and abruption of epithelial cells in tubules. When broilers received only sepiolite treated with acid (no uranyl nitrate), shortening of intestinal villi occurred. Kidney injuries were evident when uranium concentrations in kidney were 0.88 and 1.25 µg/g dry weight. It is concluded that adding of natural sepiolite to the diets of broilers can reduce uranium distribution in organs by significant amount without adverse side effects.

  13. Submerged membrane adsorption hybrid system using four adsorbents to remove nitrate from water.

    PubMed

    Kalaruban, Mahatheva; Loganathan, Paripurnanda; Kandasamy, Jaya; Vigneswaran, Saravanamuthu

    2017-04-05

    Nitrate contamination of ground and surface waters causes environmental pollution and human health problems in many parts of the world. This study tests the nitrate removal efficiencies of two ion exchange resins (Dowex 21K XLT and iron-modified Dowex 21K XLT (Dowex-Fe)) and two chemically modified bio-adsorbents (amine-grafted corn cob (AG corn cob) and amine-grafted coconut copra (AG coconut copra)) using a dynamic adsorption treatment system. A submerged membrane (microfiltration) adsorption hybrid system (SMAHS) was used for the continuous removal of nitrate with a minimal amount of adsorbents. The efficiency of membrane filtration flux and replacement rate of adsorbent were studied to determine suitable operating conditions to maintain the effluent nitrate concentration below the WHO drinking standard limit of 11.3 mg N/L. The volume of water treated and the amount of nitrate adsorbed per gramme of adsorbent for all four flux tested were in the order Dowex-Fe > Dowex > AG coconut copra > AG corn cob. The volumes of water treated (L/g adsorbent) were 0.91 and 1.85, and the amount of nitrate removed (mg N/g adsorbent) were 9.8 and 22.2 for AG corn cob and Dowex-Fe, respectively, at a flux of 15 L/(m(2)/h).

  14. Determination of Adsorption Capacity and Kinetics of Amidoxime-Based Uranium Adsorbent Braided Material in Unfiltered Seawater Using a Flume Exposure System

    SciTech Connect

    Gill, Gary A.; Kuo, Li-Jung; Strivens, Jonathan E.; Park, Jiyeon; Bonheyo, George T.; Jeters, Robert T.; Schlafer, Nicholas J.; Wood, Jordana R.

    2015-08-31

    PNNL has developed a recirculating flume system for exposing braided adsorbent material to natural seawater under realistic temperature and flow-rate exposure conditions. The flumes are constructed of transparent acrylic material they allow external light to pass into the flumes and permit photosynthetic growth of naturally present marine organisms (biofouling). Because the system consists of two flumes, replicate experiments can be conducted in which one of the flumes can be manipulated relative to the other. For example, one flume can be darkened to eliminate light exposure by placing a black tarp over the flume such that dark/light experiments can be conducted. Alternatively, two different braided adsorbents can be exposed simultaneously with no potential cross contamination issues. This report describes the first use of the PNNL flume system to study the impact of biofouling on adsorbent capacity. Experiments were conducted with the ORNL AI8 braided adsorbent material in light exposed and darkened flumes for a 42 day exposure experiment. The major objective of this effort is to develop a system for the exposure of braided adsorbent material to unfiltered seawater and to demonstrate the system by evaluating the performance of adsorption material when it is exposed to natural marine biofouling as it would be when the technology is used in the marine environment. Exposures of amidoxime-based polymeric braid adsorbents prepared by Oak Ridge Natural Laboratory (ORNL) were exposed to ambient seawater at 20°C in a flume system. Adsorption kinetics and adsorption capacity were assessed using time series determinations of uranium adsorption and one-site ligand saturation modeling. Biofouling in sunlight surface seawater has the potential to significantly add substantial biogenic mass to adsorption material when it is exposed for periods greater than 21 days. The observed biomass increase in the light flume was approximately 80 % of the adsorbent mass after 42 days. The

  15. Thermodynamic formalism of water uptakes on solid porous adsorbents for adsorption cooling applications

    NASA Astrophysics Data System (ADS)

    Sun, Baichuan; Chakraborty, Anutosh

    2014-05-01

    This Letter presents a thermodynamic formulation to calculate the amount of water vapor uptakes on various adsorbents such as zeolites, metal organic frameworks, and silica gel for the development of an advanced adsorption chiller. This formalism is developed from the rigor of the partition distribution function of each water vapor adsorptive site on adsorbents and the condensation approximation of adsorptive water molecules and is validated with experimental data. An interesting and useful finding has been established that the proposed model is thermodynamically connected with the pore structures of adsorbent materials, and the water vapor uptake highly depends on the isosteric heat of adsorption at zero surface coverage and the adsorptive sites of the adsorbent materials. Employing the proposed model, the thermodynamic trends of water vapor uptakes on various adsorbents can be estimated.

  16. Storage stability of ketones on carbon adsorbents.

    PubMed

    Prado, C; Alcaraz, M J; Fuentes, A; Garrido, J; Periago, J F

    2006-09-29

    Activated coconut carbon constitutes the more widely used sorbent for preconcentration of volatile organic compounds in sampling workplace air. Water vapour is always present in the air and its adsorption on the activated carbon surface is a serious drawback, mainly when sampling polar organic compounds, such as ketones. In this case, the recovery of the compounds diminishes; moreover, ketones can be decomposed during storage. Synthetic carbons contain less inorganic impurities and have a lower capacity for water adsorption than coconut charcoal. The aim of this work was to evaluate the storage stability of various ketones (acetone, 2-butanone, 4-methyl-2-pentanone and cyclohexanone) on different activated carbons and to study the effect of adsorbed water vapour under different storage conditions. The effect of storage temperature on extraction efficiencies was significant for each ketone in all the studied sorbents. Recovery was higher when samples were stored at 4 degrees C. The results obtained for storage stability of the studied ketones showed that the performance of synthetic carbons was better than for the coconut charcoals. The water adsorption and the ash content of the carbons can be a measure of the reactive sites that may chemisorb ketones or catalize their decomposition. Anasorb 747 showed good ketone stability at least for 7 days, except for cyclohexanone. After 30-days storage, the stability of the studied ketones was excellent on Carboxen 564. This sorbent had a nearly negligible ash content and the adsorbed water was much lower than for the other sorbents tested.

  17. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    NASA Astrophysics Data System (ADS)

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D < 6 nm do not change during HA synthesis, while the volume of pores with diameters of 6 nm < D < 9 nm shrinks slightly due to the adsorption of albumin in the pore orifices. It is established that the volume of pores with diameters D > 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  18. Extraction of palladium from acidic solutions with the use of carbon adsorbents

    SciTech Connect

    O.N. Kononova; N.G. Goryaeva; N.B. Dostovalova; S.V. Kachin; A.G. Kholmogorov

    2007-08-15

    We studied the sorption of palladium(II) on LKAU-4, LKAU-7, and BAU carbon adsorbents from model hydrochloric acid solutions and the solutions of spent palladium-containing catalysts. It was found that sorbents based on charcoal (BAU) and anthracite (LKAU-4) were characterized by high sorption capacities for palladium. The kinetics of the saturation of carbon adsorbents with palladium(II) ions was studied, and it was found that more than 60% of the initial amount of Pd(II) was recovered in a 1-h contact of an adsorbent with a model solution. This value for the solutions of spent catalysts was higher than 35%.

  19. Fabrication and thermal conductivity improvement of novel composite adsorbents adding with nanoparticles

    NASA Astrophysics Data System (ADS)

    Wu, Qibai; Yu, Xiaofen; Zhang, Haiyan; Chen, Yiming; Liu, Liying; Xie, Xialin; Tang, Ke; Lu, Yiji; Wang, Yaodong; Roskilly, Anthony Paul

    2016-10-01

    Thermal conductivity is one of key parameters of adsorbents, which will affect the overall system performance of adsorption chiller. To improve adsorbent's thermal conductivity is always one of research focuses in chemisorption field. A new chemical composite adsorbent is fabricated by adding carbon coated metal(Aluminum and Nickel) nanoparticles with three different addition amounts into the mixture of chloride salts and natural expanded graphite aiming to improve the thermal conductivity. The preparation processes and its thermal conductivity of this novel composite adsorbent are reported and summarized. Experimental results indicate that the nanoparticles are homogenously dispersed in the composite adsorbent by applying the reported preparation processes. The thermal conductivity of the composite adsorbent can averagely enlarge by 20% when the weight ratio of the added nanoparticles is 10 wt%. Moreover, carbon coated aluminum nanoparticles exhibit more effective enlargement in thermal conductivity than nickel nanoparticles. As for the composite adsorbent of CaCl2-NEG, there is a big reinforcement from 30% to 50% for Al@C nanoparticles, however only 10% in maximum caused by Ni@C nanoparticles. The proposed research provides a methodology to design and prepare thermal conductive chemical composite adsorbent.

  20. An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid.

    PubMed

    Wang, Lingling; Han, Changseok; Nadagouda, Mallikarjuna N; Dionysiou, Dionysios D

    2016-08-05

    Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO3)2·6H2O functionalization of zeolite 4A. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The synthesized materials were characterized by porosimetry analysis, scanning electron microscopy, X-Ray diffraction analysis, and high resolution transmission electron microscopy. The maximum adsorption capacity of the adsorbents at 21±1°C was about 60mgCg(-1). The results showed that the positive charge density of ZnO-coated zeolite adsorbents was proportional to the amount of ZnO coated on zeolite and thus, ZnO-coated zeolite adsorbents exhibited a greater affinity for negatively charged ions. Furthermore, the adsorption capacity of ZnO-coated zeolite adsorbents increased markedly after acid modification. Adsorption experiments demonstrated ZnO-coated zeolite adsorbents possessed high adsorption capacity to remove HA from aqueous solutions mainly due to strong electrostatic interactions between negative functional groups of HA and the positive charges of ZnO-coated zeolite adsorbents.

  1. Primary, secondary, and tertiary amines for CO2 capture: designing for mesoporous CO2 adsorbents.

    PubMed

    Ko, Young Gun; Shin, Seung Su; Choi, Ung Su

    2011-09-15

    CO(2) emissions, from fossil-fuel-burning power plants, the breathing, etc., influence the global worming on large scale and the man's work efficiency on small scale. The reversible capture of CO(2) is a prominent feature of CO(2) organic-inorganic hybrid adsorbent to sequester CO(2). Herein, (3-aminopropyl) trimethoxysilane (APTMS), [3-(methylamino)propyl] trimethoxysilane (MAPTMS), and [3-(diethylamino) propyl] trimethoxysilane (DEAPTMS) are immobilized on highly ordered mesoporous silicas (SBA-15) to catch CO(2) as primary, secondary, and tertiary aminosilica adsorbents. X-ray photoelectron spectroscopy was used to analyze the immobilized APTMS, MAPTMS, and DEAPTMS on the SBA-15. We report an interesting discovery that the CO(2) adsorption and desorption on the adsorbent depend on the amine type of the aminosilica adsorbent. The adsorbed CO(2) was easily desorbed from the adsorbent with the low energy consumption in the order of tertiary, secondary, and primary amino-adsorbents while the adsorption amount and the bonding-affinity increased in the reverse order. The effectiveness of amino-functionalized (1(o), 2(o), and 3(o) amines) SBA-15s as a CO(2) capturing agent was investigated in terms of adsorption capacity, adsorption-desorption kinetics, and thermodynamics. This work demonstrates apt amine types to catch CO(2) and regenerate the adsorbent, which may open new avenues to designing "CO(2) basket".

  2. Selective capture of water using microporous adsorbents to increase the lifetime of lubricants.

    PubMed

    Ng, Eng-Poh; Delmotte, Luc; Mintova, Svetlana

    2009-01-01

    Long live lubricants: The selective capture of water from lubricants using nanosized microporous aluminophosphate (AEI) and aluminosilicate materials was studied. Nearly 98 % of the moisture was removed from the lubricating oil under ambient conditions, resulting in a significant improvement in the lubricating service lifetime. Moreover, both the lubricant and the microporous sorbents can be recovered and reused.The selective capture of water from lubricants using nanosized microporous aluminophosphate and aluminosilicate materials was studied with an aim to increase the lifetime of the lubricating mineral oil. The amount of water present in oxidized lubricating oil before and after treatment with microporous materials was studied by FTIR spectroscopy and determined quantitatively using the Karl Fischer titration method. Nanosized aluminophosphate revealed a high selectivity for water without adsorbing other additives, in contrast to nanosized aluminosilicates which also adsorb polar oxidation products and ionic additives. About 98 % of the initial moisture could be removed from the lubricating oil under ambient conditions, resulting in a significant improvement in the lubricating service lifetime. Moreover, no by-products are formed during the process and both the lubricant and the sorbents can be recovered and reused, thus the method is environmentally friendly.

  3. Classical dynamics of adsorbate-surface systems: Application to nonthermal desorption

    NASA Astrophysics Data System (ADS)

    Dzegilenko, Fedor; Herbst, Eric

    1994-06-01

    The classical trajectory approach has been used to study the nonthermal desorption of CO from a variety of model surfaces to which it is weakly adsorbed. In addition to three degrees of freedom for the CO adsorbate (bond stretching, physisorption, libration), a significant number of lattice degrees of freedom have been included using the generalized Langevin approximation. Nonthermal amounts of energy have been put into both the CO stretching and librational modes at t=0. We find that for initial values of the stretching quantum number vstr=0-10, desorption does not take place at all within 12.5 ps unless there is also significant librational excitation. The detailed mechanism by which librational energy causes desorption is discussed. The role of the surface is also explored; we find that the probability of desorption is a nonmonotonic function of the Debye frequency of the solid in the range 28-915 cm-1, and is larger for lattices with either ``high'' or ``low'' Debye frequencies than for lattices with ``intermediate'' Debye frequencies. This result is partially explained in terms of resonances between low frequency libration and physisorption modes and high frequency phonon modes.

  4. A novel fiber-based adsorbent technology

    SciTech Connect

    Reynolds, T.A.

    1997-10-01

    In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry.

  5. Molecularly Imprinted Filtering Adsorbents for Odor Sensing

    PubMed Central

    Shinohara, Sho; Chiyomaru, You; Sassa, Fumihiro; Liu, Chuanjun; Hayashi, Kenshi

    2016-01-01

    Versatile odor sensors that can discriminate among huge numbers of environmental odorants are desired in many fields, including robotics, environmental monitoring, and food production. However, odor sensors comparable to an animal’s nose have not yet been developed. An animal’s olfactory system recognizes odor clusters with specific molecular properties and uses this combinatorial information in odor discrimination. This suggests that measurement and clustering of odor molecular properties (e.g., polarity, size) using an artificial sensor is a promising approach to odor sensing. Here, adsorbents composed of composite materials with molecular recognition properties were developed for odor sensing. The selectivity of the sensor depends on the adsorbent materials, so specific polymeric materials with particular solubility parameters were chosen to adsorb odorants with various properties. The adsorption properties of the adsorbents could be modified by mixing adsorbent materials. Moreover, a novel molecularly imprinted filtering adsorbent (MIFA), composed of an adsorbent substrate covered with a molecularly imprinted polymer (MIP) layer, was developed to improve the odor molecular recognition ability. The combination of the adsorbent and MIP layer provided a higher specificity toward target molecules. The MIFA thus provides a useful technique for the design and control of adsorbents with adsorption properties specific to particular odor molecules. PMID:27886070

  6. Results of testing various natural gas desulfurization adsorbents

    NASA Astrophysics Data System (ADS)

    Israelson, Gordon

    2004-06-01

    This article presents the results of testing many commercially available and some experimental sulfur adsorbents. The desired result of our testing was to find an effective method to reduce the quantity of sulfur in natural gas to less than 100 ppb volume (0.1 ppm volume). An amount of 100 ppb sulfur is the maximum limit permitted for Siemens Westinghouse solid oxide fuel cells (SOFCs). The tested adsorbents include some that rely only on physical adsorption such as activated carbon, some that rely on chemisorption such as heated zinc oxide, and some that may use both processes. The testing was performed on an engineering scale with beds larger than those used for typical laboratory tests. All tests were done at about 3.45 barg (50 psig). The natural gas used for testing was from the local pipeline in Pittsburgh and averaged 6 ppm volume total sulfur. The primary sulfur species were dimethyl sulfide (DMS), isopropyl mercaptan, tertiary butyl mercaptan, and tetrahydrothiophene. Some tests required several months to achieve a sulfur breakthrough of the bed. It was found that DMS always came through a desulfurizer bed first, independent of adsorption process. Since the breakthrough of DMS always exceeds the 100 ppb SOFC sulfur limit before other sulfurs were detected, an index was created to rate the adsorbents in units of ppm DMS × absorbent bed volume. This index is useful for calculating the expected adsorbent bed lifetime before sulfur breakthrough when the inlet natural gas DMS content is known. The adsorbents that are included in these reports were obtained from suppliers in the United States, the Netherlands, Japan, and England. Three activated carbons from different suppliers were found to have identical performance in removing DMS. One of these activated carbons was operated at four different space velocities and again showed the same performance. When using activated carbon as the basis of comparison for other adsorbents, three high-performance adsorbents

  7. Development of carbon dioxide adsorbent from rice husk char

    NASA Astrophysics Data System (ADS)

    Abang, S.; Janaun, J.; Anisuzzaman, S. M.; Ikhwan, F. S.

    2016-06-01

    This study was mainly concerned about the development of carbon dioxide (CO2) adsorbent from rice husk (RH). Several chemical treatments were used to produce activated rice husk char (RHAC) from RH. Initially the RH was refluxed with 3M of sodium hydroxide (NaOH) solution, activation followed by using 0.5M of zinc chloride (ZnCl2) solution and finally acidic treatment by using 0.1M of hydrochloric acid (HCl). Then, the RHAC was functionalized by using 3-chloropropylamine hydrochloride (3-CPA) and noted as RHN. RHN samples were characterized with scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), fourier transform infrared spectroscopy (FTIR). Based on the SEM, the RHN sample had a large pore diameter compared to RH sample after being treated. Based on MIP data, the average pore diameter between RH and RHAC samples were increased significantly from 0.928 microns to 1.017 microns. The RHN sample also had higher total porosity (%) compared to RHAC and RH (58.45%, 47.82% and 45.57% respectively). The total specific surface area of the sample was much increasing from RHO to RHAC (29.17 m2/g and 62.94 m2/g respectively) and slightly being decreasing from RHAC to RHN (58.88 m2/g). FTIR result showed the present of weak band at 1587 cm-1 which demonstrating of the amine group present on the sample. The CO2 capture result showed that the decreasing of operating temperature can increase the breakthrough time of CO2 capture. On the contrary decreasing of CO2 gas flow rate can increase the breakthrough time of CO2 capture. The highest total amount of CO2 adsorbed was 25338.57 mg of CO2/g of RHN sample by using 100 mL/min of gas flow rate at 30oC. Based on adsorption isotherm analysis, the Freundlich isotherm was the best isotherm to describe the CO2 adsorption on the sample.

  8. Visualization and Measurement of Adsorption/Desorption Process of Ethanol in Activated Carbon Adsorber

    NASA Astrophysics Data System (ADS)

    Asano, Hitoshi; Murata, Kenta; Takenaka, Nobuyuki; Saito, Yasushi

    Adsorption refrigerator is one of the efficient tools for waste heat recovery, because the system is driven by heat at relative low temperature. However, the coefficient of performance is low due to its batch operation and the heat capacity of the adsorber. In order to improve the performance, it is important to optimize the configuration to minimize the amount of driving heat, and to clarify adsorption/desorption phenomena in transient conditions. Neutron radiography was applied to visualize and measure the adsorption amount distribution in an adsorber. The visualization experiments had been performed at the neutron radiography facility of E-2 port of Kyoto University Research Reactor. Activated carbon and ethanol were used as the adsorbent and refrigerant. From the acquired radiographs, adsorption amount was quantitatively measured by applying the umbra method using a checkered neutron absorber with boron powder. Then, transient adsorption and desorption processes of a rectangular adsorber with 84 mm in width, 50 mm in height and 20 mm in depth were visualized. As the result, the effect of fins in the adsorbent layer on the adsorption amount distribution was clearly visualized.

  9. The uranium from seawater program at PNNL: Overview of marine testing, adsorbent characterization, adsorbent durability, adsorbent toxicity, and deployment studies

    DOE PAGES

    Gill, Gary A.; Kuo, Li -Jung; Janke, Christopher James; ...

    2016-02-07

    The Pacific Northwest National Laboratory's (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacitymore » and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage. Marine testing

  10. The uranium from seawater program at PNNL: Overview of marine testing, adsorbent characterization, adsorbent durability, adsorbent toxicity, and deployment studies

    SciTech Connect

    Gill, Gary A.; Kuo, Li -Jung; Janke, Christopher James; Park, Jiyeon; Jeters, Robert T.; Bonheyo, George T.; Pan, Horng -Bin; Wai, Chien; Khangaonkar, Tarang P.; Bianucci, Laura; Wood, Jordana R.; Warner, Marvin G.; Peterson, Sonja; Abrecht, David G.; Mayes, Richard T.; Tsouris, Costas; Oyola, Yatsandra; Strivens, Jonathan E.; Schlafer, Nicholas J.; Addleman, Shane R.; Chouyyok, Wilaiwan; Das, Sadananda; Kim, Jungseung; Buesseler, Ken; Breier, Crystal; D'Alessandro, Evan

    2016-02-07

    The Pacific Northwest National Laboratory's (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacity and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage. Marine testing at Woods

  11. Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

    SciTech Connect

    Janke, Chris; Yatsandra, Oyola; Mayes, Richard; none,; Gill, Gary; Li-Jung, Kuo; Wood, Jordana; Sadananda, Das

    2014-04-30

    ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

  12. Determinants of Protein Elution Rates from Preparative Ion-Exchange Adsorbents

    PubMed Central

    Angelo, James M.; Lenhoff, Abraham M.

    2016-01-01

    The rate processes involved in elution in preparative chromatography can affect both peak resolution and hence selectivity as well as practical factors such as facility fit. These processes depend on the physical structure of the adsorbent particles, the amount of bound solute, the solution conditions for operation or some combination of these factors. Ion-exchange adsorbents modified with covalently attached or grafted polymer layers have become widely used in preparative chromatography. Their often easily accessible microstructures offer substantial binding capacities for biomolecules, but elution has sometimes been observed to be undesirably slow. In order to determine which physicochemical phenomena control elution behavior, commercially available cellulosic, dextran-grafted and unmodified agarose materials were characterized here by their uptake and elution profiles at various conditions, including different degrees of loading. Elution data were analyzed under the assumption of purely diffusion-limited control, including the role of pore structure properties such as porosity and tortuosity. In general, effective elution rates decreased with the reduction of accessible pore volume, but differences among different proteins indicated the roles of additional factors. Additional measurements and analysis, including the use of confocal laser scanning microscopy to observe elution within single chromatographic particles, indicated the importance of protein association within the particle during elution. The use of protein stabilizing agents was explored in systems presenting atypical elution behavior, and L-arginine and disaccharide excipients were shown to alleviate the effects for one protein, lysozyme, in the presence of sodium chloride. Incorporation of these excipients into eluent buffer gave rise to faster elution and significantly lower pool volumes in elution from polymer-modified adsorbents. PMID:26948763

  13. Determinants of protein elution rates from preparative ion-exchange adsorbents.

    PubMed

    Angelo, James M; Lenhoff, Abraham M

    2016-04-01

    The rate processes involved in elution in preparative chromatography can affect both peak resolution and hence selectivity as well as practical factors such as facility fit. These processes depend on the physical structure of the adsorbent particles, the amount of bound solute, the solution conditions for operation or some combination of these factors. Ion-exchange adsorbents modified with covalently attached or grafted polymer layers have become widely used in preparative chromatography. Their often easily accessible microstructures offer substantial binding capacities for biomolecules, but elution has sometimes been observed to be undesirably slow. In order to determine which physicochemical phenomena control elution behavior, commercially available cellulosic, dextran-grafted and unmodified agarose materials were characterized here by their elution profiles at various conditions, including different degrees of loading. Elution data were analyzed under the assumption of purely diffusion-limited control, including the role of pore structure properties such as porosity and tortuosity. In general, effective elution rates decreased with the reduction of accessible pore volume, but differences among different proteins indicated the roles of additional factors. Additional measurements and analysis, including the use of confocal laser scanning microscopy to observe elution within single chromatographic particles, indicated the importance of protein association within the particle during elution. The use of protein stabilizing agents was explored in systems presenting atypical elution behavior, and l-arginine and disaccharide excipients were shown to alleviate the effects for one protein, lysozyme, in the presence of sodium chloride. Incorporation of these excipients into eluent buffer gave rise to faster elution and significantly lower pool volumes in elution from polymer-modified adsorbents.

  14. Application of near infrared spectroscopy for the determination of adsorbed p-nitrophenol on HDTMA organoclay--implications for the removal of organic pollutants from water.

    PubMed

    Zhou, Qin; Xi, Yunfei; He, Hongping; Frost, Ray L

    2008-03-01

    NIR spectroscopy has been used to measure the adsorption of p-nitrophenol on untreated montmorillonite and surfactant exchanged montmorillonite. p-Nitrophenol is characterised by an intense NIR band at 8890 cm(-1) which shifts to 8840 cm(-1) upon adsorption on organoclay. The band was not observed for p-nitrophenol adsorbed on untreated montmorillonite. Both the montmorillonite and the surfactant modified montmorillonite are characterised by NIR bands at 7061 and 6791 cm(-1). The organoclay is characterised by two prominent bands at 5871 and 5667 cm(-1) assigned to the fundamental overtones of the mid-IR bands at 2916 and 2850 cm(-1). A band at 6017 cm(-1) is attributed to the p-nitrophenol adsorbed on the organoclay. The band is not observed for the montmorillonite with adsorbed p-nitrophenol. It is concluded that p-nitrophenol is adsorbed to significantly greater amounts on the organoclay compared with the untreated montmorillonite. The implication is that organoclays are most useful for removing organic molecules from water through adsorption.

  15. A study of the potential application of nano-Mg(OH)2 in adsorbing low concentrations of uranyl tricarbonate from water.

    PubMed

    Cao, Qing; Huang, Feng; Zhuang, Zanyong; Lin, Zhang

    2012-04-07

    This work aims at the investigation of nano-Mg(OH)(2) as a promising adsorbent for uranium recovery from water. Systematic analysis including the uranium adsorption isotherm, the kinetics and the thermodynamics of adsorption of low concentrations of uranyl tricarbonate (0.1-20 mg L(-1)) by nano-Mg(OH)(2) was carried out. The results showed a spontaneous and exothermic uranium adsorption process by Mg(OH)(2), which could be well described with pseudo second order kinetics. Surface site calculation and zeta potential measurement further demonstrated that UO(2)(CO(3))(3)(4-) was a monolayer adsorbed onto nano-Mg(OH)(2) by electrostatic forces. Accordingly, the adsorption behavior met the conditions of the Langmuir isotherm. Moreover, in most of the reported literature, nano-Mg(OH)(2) had a higher UO(2)(CO(3))(3)(4-) adsorption affinity b, which implied a higher adsorption amount at equilibrium in a dilute adsorbate system. The significance of the adsorption affinity b for choosing and designing adsorbents with respect to low concentration of resources/pollutants treatment has also been assessed.

  16. Complexation of trace metals by adsorbed natural organic matter

    USGS Publications Warehouse

    Davis, J.A.

    1984-01-01

    The adsorption behavior and solution speciation of Cu(II) and Cd(II) were studied in model systems containing colloidal alumina particles and dissolved natural organic matter. At equilibrium a significant fraction of the alumina surface was covered by adsorbed organic matter. Cu(II) was partitioned primarily between the surface-bound organic matter and dissolved Cu-organic complexes in the aqueous phase. Complexation of Cu2+ with the functional groups of adsorbed organic matter was stronger than complexation with uncovered alumina surface hydroxyls. It is shown that the complexation of Cu(II) by adsorbed organic matter can be described by an apparent stability constant approximately equal to the value found for solution phase equilibria. In contrast, Cd(II) adsorption was not significantly affected by the presence of organic matter at the surface, due to weak complex formation with the organic ligands. The results demonstrate that general models of trace element partitioning in natural waters must consider the presence of adsorbed organic matter. ?? 1984.

  17. Adsorbate Diffusion on Transition Metal Nanoparticles

    DTIC Science & Technology

    2015-01-01

    systematically studied adsorption and diffusion of atomic and diatomic species (H, C, N, O, CO, and NO) on nanometer-sized Pt and Cu nanoparticles with...species and two diatomic molecules (H, C, N, O, CO, and NO) as adsorbates and study the adsorption and diffusion of these adsorbates across the edges

  18. An adsorbent with a high adsorption capacity obtained from the cellulose sludge of industrial residues.

    PubMed

    Orlandi, Géssica; Cavasotto, Jéssica; Machado, Francisco R S; Colpani, Gustavo L; Magro, Jacir Dal; Dalcanton, Francieli; Mello, Josiane M M; Fiori, Márcio A

    2017-02-01

    One of the major problems in effluent treatment plants of the cellulose and paper industry is the large amount of residual sludge generated. Therefore, this industry is trying to develop new methods to treat such residues and to use them as new products, such as adsorbents. In this regard, the objective of this work was to develop an adsorbent using the raw activated sludge generated by the cellulose and paper industry. The activated cellulose sludge, after being dried, was chemically activated with 42.5% (v/v) phosphoric acid at 85 °C for 1 h and was charred at 500 °C, 600 °C and 700 °C for 2 h. The efficiency of the obtained adsorbent materials was evaluated using kinetic tests with methylene blue solutions. Using the adsorption kinetics, it was verified that the three adsorbents showed the capacity to adsorb dye, and the adsorbent obtained at a temperature of 600 °C showed the highest adsorption capacity of 107.1 mg g(-1). The kinetic model that best fit the experimental data was pseudo-second order. The Langmuir-Freudlich isotherm adequately described the experimental data. As a result, the cellulose sludge generated by the cellulose and paper industries could be used as an adsorbent.

  19. Retention of radium from thermal waters on sand filters and adsorbents.

    PubMed

    Elejalde, C; Herranz, M; Idoeta, R; Legarda, F; Romero, F; Baeza, A

    2007-06-18

    This study was focussed on laboratory experiences of retention of radium from one thermal water on sand filters and adsorbents, trying to find an easy method for the elimination in drinkable waters polluted with this natural radio-nuclide. A thermal water from Cantabria (Spain) was selected for this work. Retention experiences were made with columns of 35 mm of diameter containing 15 cm layers of washed river sand or 4 cm layers of zeolite A3, passing known volumes of thermal water at flows between 4 and 40 ml/min with control of the retained radium by determining the amount in the water after the treatment. The statistical analysis of data suggests that retention depends on the flow and the volume passed through the columns. As additional adsorbents were used kaolin and a clay rich in illite. Jar-test experiences were made agitating known weights of adsorbents with the selected thermal water, with addition of flocculants and determination of radium in filtrated water after the treatment. Data suggest that retention is related to the weight of adsorbent used, but important quantities of radium seem remain in solution for higher amounts of adsorbents, according to the statistical treatment of data. The elution of retained radium from columns or adsorbents, previously used in experiences, should be the aim of a future research.

  20. Database of Novel and Emerging Adsorbent Materials

    National Institute of Standards and Technology Data Gateway

    SRD 205 NIST/ARPA-E Database of Novel and Emerging Adsorbent Materials (Web, free access)   The NIST/ARPA-E Database of Novel and Emerging Adsorbent Materials is a free, web-based catalog of adsorbent materials and measured adsorption properties of numerous materials obtained from article entries from the scientific literature. Search fields for the database include adsorbent material, adsorbate gas, experimental conditions (pressure, temperature), and bibliographic information (author, title, journal), and results from queries are provided as a list of articles matching the search parameters. The database also contains adsorption isotherms digitized from the cataloged articles, which can be compared visually online in the web application or exported for offline analysis.

  1. NOx adsorber and method of regenerating same

    DOEpatents

    Endicott, Dennis L.; Verkiel, Maarten; Driscoll, James J.

    2007-01-30

    New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.

  2. Picosecond adsorbate dynamics at condensed phase interfaces

    SciTech Connect

    Scott, T.W.; Chang, Y.J.; Martorell, J.

    1993-12-31

    Picosecond surface second harmonic generation has been used to probe a variety of elementary adsorbate reactions at liquid-solid interfaces. Electron transfer reactions at semiconductor-liquid junctions, geminate recombination of photogenerated free radical pairs and the orientational dynamics of dipolar adsorbates have all been explored in varying degrees of detail. These kinetic studies have led to a detailed analysis of adsorbate detection on the surface of non-centrosymmetric substrates as well as the use of total internal reflection geometries for signal enhancement from optically absorbing liquids. Particular emphasis has been placed on the static and dynamic characterization of adsorbate orientational distribution functions and how these are determined from the torque exerted on adsorbates by the angular part of the molecule-surface interaction potential.

  3. Fluorescence dynamics of microsphere-adsorbed sunscreens

    NASA Astrophysics Data System (ADS)

    Krishnan, R.

    2005-03-01

    Sunscreens are generally oily substances which are prepared in organic solvents, emulsions or dispersions with micro- or nanoparticles. These molecules adsorb to and integrate into skin cells. In order to understand the photophysical properties of the sunscreen, we compare steady-state and time-resolved fluorescence in organic solvent of varying dielectric constant ɛ and adsorbed to polystyrene microspheres and dispersed in water. Steady-state fluorescence is highest and average fluorescence lifetime longest in toluene, the solvent of lowest ɛ. However, there is no uniform dependence on ɛ. Sunscreens PABA and padimate-O show complex emission spectra. Microsphere-adsorbed sunscreens exhibit highly non-exponential decay, illustrative of multiple environments of the adsorbed molecule. The heterogeneous fluorescence dynamics likely characterizes sunscreen adsorbed to cells.

  4. Nanovalved Adsorbents for CH4 Storage.

    PubMed

    Song, Zhuonan; Nambo, Apolo; Tate, Kirby L; Bao, Ainan; Zhu, Minqi; Jasinski, Jacek B; Zhou, Shaojun J; Meyer, Howard S; Carreon, Moises A; Li, Shiguang; Yu, Miao

    2016-05-11

    A novel concept of utilizing nanoporous coatings as effective nanovalves on microporous adsorbents was developed for high capacity natural gas storage at low storage pressure. The work reported here for the first time presents the concept of nanovalved adsorbents capable of sealing high pressure CH4 inside the adsorbents and storing it at low pressure. Traditional natural gas storage tanks are thick and heavy, which makes them expensive to manufacture and highly energy-consuming to carry around. Our design uses unique adsorbent pellets with nanoscale pores surrounded by a coating that functions as a valve to help manage the pressure of the gas and facilitate more efficient storage and transportation. We expect this new concept will result in a lighter, more affordable product with increased storage capacity. The nanovalved adsorbent concept demonstrated here can be potentially extended for the storage of other important gas molecules targeted for diverse relevant functional applications.

  5. Adsorbate-metal bond effect on empirical determination of surface plasmon penetration depth.

    PubMed

    Kegel, Laurel L; Menegazzo, Nicola; Booksh, Karl S

    2013-05-21

    The penetration depth of surface plasmons is commonly determined empirically from the observed response for adsorbate loading on gold surface plasmon resonance (SPR) substrates. However, changes in the SPR spectrum may originate from both changes in the effective refractive index near the metal surface and changes in the metal permittivity following covalent binding of the adsorbate layer. Herein, the significance of incorporating an additional adsorbate-metal bonding effect in the calculation is demonstrated in theory and in practice. The bonding effect is determined from the nonzero intercept of a SPR shift versus adsorbate thickness calibration and incorporated into the calculation of penetration depth at various excitation wavelengths. Determinations of plasmon penetration depth with and without the bonding response for alkanethiolate-gold are compared and are shown to be significantly different for a thiol monolayer adsorbate system. Additionally, plasmon penetration depth evaluated with bonding effect compensation shows greater consistency over different adsorbate thicknesses and better agreement with theory derived from Maxwell's equation, particularly for adsorbate thicknesses that are much smaller (<5%) than the plasmon penetration depth. The method is also extended to a more practically applicable polyelectrolyte multilayer adsorbate system.

  6. Chemical effects on vibrational properties of adsorbed molecules on metal surfaces: Coverage dependence

    NASA Astrophysics Data System (ADS)

    Ueba, H.

    1987-10-01

    Vibrational properties of chemisorbed molecules on metal surfaces are studied with a focus on the coverage dependent chemical shift of the frequencies. Available experimental data of a CO adsorption on transition metal and noble metal surfaces are analyzed in the light of the coverage dependent back-donation into the 2 π* orbitals of chemisorbed CO molecules. The vibrational frequency ωCO of the intramolecular stretching mode exhibits a downward shift of varying magnitude, depending on the amount of back-donation into the 2 π* orbitals of the chemisorbed CO. On increasing the coverage θ, ωCO usually increases due to the dipole-dipole interaction. On Cu surfaces, however, the shifts are relatively small, or in some cases, negative. So far, this anomalous frequency shift with θ is understood as a result of competitive effect between the upward dipole Ωdip and the downward chemical shift Ωchem associated with back-donation. The purpose of this paper is to establish the possible origin of the downward frequency shift through the electronic properties of an incomplete monolayer of adsorbates. The adsorbate density of states ρa is calculated by means of the coherent potential approximation, in which the electron hopping between the adsorbates (band formation effect) and the depolarization effect due to the proximity of ionized adsorbed molecules are taken into account. The change of the occupied portion of ρa and ρa ( ɛF) at the Fermi level ɛF with increasing θ then manifests itself in the coverage dependent Ωchem not only due to the static back-donation, but also due to the dynamical charge fluctuation during vibrational excitation. It is found that in a weakly chemisorbed system, such as CO/Cu, the negative Ωchem amounts to Ωdip at low θ. Consequently the apparent total frequency shift remains almost constant. As the coverage increases, Ωchem becomes larger than Ωdip due to the band effect. It is also shown that the variation of the back

  7. Parallel pore and surface diffusion of levulinic acid in basic polymeric adsorbents.

    PubMed

    Liu, Baojian; Yang, Yiwen; Ren, Qilong

    2006-11-03

    The equilibrium and kinetics of levulinic acid (LA) adsorption on two basic polymeric adsorbents, 335 (highly porous gel) and D315 (macroreticular), were investigated. Experimental adsorption rates in batch stirred vessels under a variety of operating conditions were described successfully by the parallel pore and surface diffusion model taking into account external mass transfer and nonlinear Toth isotherm. The film-pore diffusion model was matched with the rate data and the resulting apparent pore diffusivities were strongly concentration-dependent and approached to a constant value for 335 adsorbent. Thus, the constant value was taken as the accurate pore diffusivity, while the pore diffusivity in D315 was estimated from the particle porosity. The surface diffusivities decreased with increasing initial bulk concentration for both adsorbents. The inverse concentration dependence was correlated reasonably well to the change of isosteric heat of adsorption as amount adsorbed.

  8. Effect of adsorbed chlorine and oxygen on the shear strength of iron and copper junctions

    NASA Technical Reports Server (NTRS)

    Wheeler, D. R.

    1976-01-01

    Static-friction experiments were performed in ultrahigh vacuum at room temperature on copper, iron, and steel contacts selectively contaminated with oxygen and chlorine in submonolayer amounts. The concentration of the adsorbates was determined with Auger electron spectroscopy and was measured relative to the saturation concentration of oxygen on iron (concentration, 1.0). The coefficient of static friction decreased with increasing adsorbate concentration; however, it was independent of the type of metal and the adsorbate species. The results compared satisfactorily with an extension of the junction growth theory to heterogeneous interfaces. The reduction in interfacial shear strength was measured by the ratio of the shear strength of the interface with an adsorbate concentration of 1.0 and the strength of the clean metal interface. This ratio was about 0.835 for all the systems tested.

  9. The effect of mineral bond strength and adsorbed water on fault gouge frictional strength

    USGS Publications Warehouse

    Morrow, C.A.; Moore, Diane E.; Lockner, D.A.

    2000-01-01

    Recent studies suggest that the tendency of many fault gouge minerals to take on adsorbed or interlayer water may strongly influence their frictional strength. To test this hypothesis, triaxial sliding experiments were conducted on 15 different single-mineral gouges with various water-adsorbing affinities. Vacuum dried samples were sheared at 100 MPa, then saturated with water and sheared farther to compare dry and wet strengths. The coefficients of friction, μ, for the dry sheet-structure minerals (0.2-0.8), were related to mineral bond strength, and dropped 20-60% with the addition of water. For non-adsorbing minerals (μ = 0.6-0.8), the strength remained unchanged after saturation. These results confirm that the ability of minerals to adsorb various amounts of water is related to their relative frictional strengths, and may explain the anomalously low strength of certain natural fault gouges.

  10. Effect of adsorbed chlorine and oxygen on shear strength of iron and copper junctions

    NASA Technical Reports Server (NTRS)

    Wheeler, D. R.

    1975-01-01

    Static friction experiments were performed in ultrahigh vacuum at room temperature on copper, iron, and steel contacts selectively contaminated with oxygen and chlorine in submonolayer amounts. The concentration of the adsorbates was determined with Auger electron spectroscopy and was measured relative to the saturation concentration of oxygen on iron (concentration 1.0). The coefficient of static friction decreased with increasing adsorbate concentration. It was independent of the metal and the adsorbate. The results compared satisfactorily with an extension of the junction growth theory to heterogeneous interfaces. The reduction in interfacial shear strength was measured by the ratio sub a/sub m where sub a is the shear strength of the interface with an adsorbate concentration of 1.0, and sub m is the strength of the clean metal interface. This ratio was 0.835 + or - 0.012 for all the systems tested.

  11. Inorganic chemically active adsorbents (ICAAs)

    SciTech Connect

    Ally, M.R.; Tavlarides, L.

    1997-10-01

    Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL`s Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants.

  12. Detection of adsorbed water and hydroxyl on the Moon.

    PubMed

    Clark, Roger N

    2009-10-23

    Data from the Visual and Infrared Mapping Spectrometer (VIMS) on Cassini during its flyby of the Moon in 1999 show a broad absorption at 3 micrometers due to adsorbed water and near 2.8 micrometers attributed to hydroxyl in the sunlit surface on the Moon. The amounts of water indicated in the spectra depend on the type of mixing and the grain sizes in the rocks and soils but could be 10 to 1000 parts per million and locally higher. Water in the polar regions may be water that has migrated to the colder environments there. Trace hydroxyl is observed in the anorthositic highlands at lower latitudes.

  13. Detection of adsorbed water and hydroxyl on the moon

    USGS Publications Warehouse

    Clark, R.N.

    2009-01-01

    Data from the Visual and Infrared Mapping Spectrometer (VIAAS) on Cassini during its flyby of the AAoon in 1999 show a broad absorption at 3 micrometers due to adsorbed water and near 2.8 micrometers attributed to hydroxyl in the sunlit surface on the AAoon. The amounts of water indicated in the spectra depend on the type of mixing and the grain sizes in the rocks and soils but could be 10 to 1000 parts per million and locally higher. Water in the polar regions may be water that has migrated to the colder environments there. Trace hydroxyl is observed in the anorthositic highlands at lower latitudes.

  14. R&D for graft adsorbents by radiation processing

    NASA Astrophysics Data System (ADS)

    Seko, Noriaki; Tamada, Masao

    Fibrous adsorbent for removal and recovery of metal ions have been synthesized by graft polymerization. In the grafting, the functional groups which have high selectivity against for target metal ions such as Fe, Sc, As, and U are introduced onto nonwoven fabric. When the monomer has a chelate group which makes selective coordination bond to specific these ions, it was directly grafted on the trunk polymer. In the case of precursor monomer having functional groups such as epoxy ring, the grafted trunk fabric is chemically modified. The resultant fibrous adsorbent leads the swift adsorption of metal ions. This property by using fibrous material can reduce the column size of adsorbent in the purification of waste water. The size of purification equipment becomes quite compact and that implies total volume of equipment can reduce. Instead of organic solvent, emulsion system which disperses monomer micelles in water with assistance of surfactant was found to accelerate the graft polymerization. This means the air pollution from organic solvent can be avoided by water system grafting. Furthermore, since the emulsion grafting was highly efficient, the required irradiation dose was considerably lower compared to general organic solvent system. As a result, the emulsion grafting has enormous potential for natural polymer to use as a trunk material for grafting. If a natural polymer such as cellulose can be used, the dependence on petroleum resources, the amount of industrial waste and the generation of carbon dioxide will be reduced to some extent.

  15. Activity of alkaline phosphatase adsorbed and grafted on "polydopamine" films.

    PubMed

    Ball, Vincent

    2014-09-01

    The oxidation of dopamine in slightly basic solutions and in the presence of oxygen as an oxidant allows for the deposition of dopamine-eumelanin ("polydopamine") films on almost all kinds of materials allowing for an easy secondary functionalization. Molecules carrying nucleophilic groups like thiols and amines can be easily grafted on those films. Herein we show that alkaline phosphatase (ALP), as a model enzyme, adsorbs to "polydopamine" films and part of the adsorbed enzyme is rapidly desorbed in contact with Tris buffer. However a significant part of the enzyme remains irreversibly adsorbed and keeps some enzymatic activity for at least 2 weeks whereas ALP adsorbed on quartz slides is rapidly and quantitatively deactivated. In addition we estimated the Michaelis constant Km of the enzyme irreversibly bound to the "polydopamine" film. The Michaelis constant, and hence the affinity constant between paranitrophenol phosphate and ALP are almost identical between the enzyme bound on the film and the free enzyme in solution. Complementarily, it was found that "polydopamine" films display some phosphatase like catalytic activity.

  16. Interactions of organic contaminants with mineral-adsorbed surfactants.

    PubMed

    Zhu, Lizhong; Chen, Baoliang; Tao, Shu; Chiou, Cary T

    2003-09-01

    Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insightto interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

  17. Interactions of organic contaminants with mineral-adsorbed surfactants

    USGS Publications Warehouse

    Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

    2003-01-01

    Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

  18. Chiral switching by spontaneous conformational change in adsorbed organic molecules.

    PubMed

    Weigelt, Sigrid; Busse, Carsten; Petersen, Lars; Rauls, Eva; Hammer, Bjørk; Gothelf, Kurt V; Besenbacher, Flemming; Linderoth, Trolle R

    2006-02-01

    Self-assembly of adsorbed organic molecules is a promising route towards functional surface nano-architectures, and our understanding of associated dynamic processes has been significantly advanced by several scanning tunnelling microscopy (STM) investigations. Intramolecular degrees of freedom are widely accepted to influence ordering of complex adsorbates, but although molecular conformation has been identified and even manipulated by STM, the detailed dynamics of spontaneous conformational change in adsorbed molecules has hitherto not been addressed. Molecular surface structures often show important stereochemical effects as, aside from truly chiral molecules, a large class of so-called prochiral molecules become chiral once confined on a surface with an associated loss of symmetry. Here, we investigate a model system in which adsorbed molecules surprisingly switch between enantiomeric forms as they undergo thermally induced conformational changes. The associated kinetic parameters are quantified from time-resolved STM data whereas mechanistic insight is obtained from theoretical modelling. The chiral switching is demonstrated to enable an efficient channel towards formation of extended homochiral surface domains. Our results imply that appropriate prochiral molecules may be induced (for example, by seeding) to assume only one enantiomeric form in surface assemblies, which is of relevance for chiral amplification and asymmetric heterogenous catalysis.

  19. Evaluation of Adsorbed Arsenic and Potential Contribution to Shallow Groundwater in Tulare Lake Bed Area, Tulare Basin, California

    USGS Publications Warehouse

    Gao, S.; Fujii, R.; Chalmers, A.T.; Tanji, K.K.

    2004-01-01

    Elevated As concentrations in shallow groundwater in parts of the Tulare Basin, California, are a concern because of potential migration into deeper aquifers that could serve as a source of future drinking water. The objectives of this study were to evaluate adsorbed As and the potential contribution to groundwater using (i) isotopic dilution, (ii) successive extraction with an electrolyte solution resembling the pore-water chemical composition, and (iii) PO4 exchange for As. Sediment samples collected from 2 to 4 m below land surface in the Tulare Lake bed area contained a total As concentration of 24 mg As kg-1. Pore water extracted under hydraulic pressure contained a total As concentration of 590 ??g As L-1, which predominantly contained As as arsenate [As(V), 97%], a minor amount of arsenite [As(III), 3%], and non-detectable organic As. The isotopic dilution method [73As(V)] estimated that the concentration of adsorbed As(V) on the sediment was 5.7 mg As kg-1 at pH 8.5 and 6.7 mg As kg-1 at pH 7.5, respectively. Fourteen successive 24-h extractions with the artificial pore water released up to 57 to 61% of the adsorbed As(V) that was determined by isotopic dilution, indicating that only a portion of the adsorbed As could be released to groundwater. The phosphate-exchangeable As (0.1 M PO4, pH 8.5 or 7.5) was 63% of the isotopically exchangeable As(V). Thus, extraction of As by 0.1 M PO4 at ambient pHs is recommended as a method to determine the potential amount of As(V) on sediments that could be released to the solution phase. The overall results indicated that adsorbed As could be a significant source of As to groundwater. However, other factors that affect As transport such as the leaching rate need to be considered.

  20. Novel adsorbent applicability for decontamination of printing wastewater

    NASA Astrophysics Data System (ADS)

    Kiurski, Jelena; Oros, Ivana; Ranogajec, Jonjaua; Kecic, Vesna

    2013-04-01

    Adsorption capacity of clayey minerals can be enhanced by replacing the natural exchangeable cations with organic cations, which makes the clay surface more hydrophobic. Different solids such as activated carbon, clay minerals, zeolites, metal oxides and organic polymers have been tested as effective adsorbents. On a global scale, clays have a large applicability for decontamination, purification of urban and industrial residual waters, protection of waste disposal areas, and purification of industrial gases and so on. Clay derivative materials with high adsorption capacities are very attractive from an economical point of view. Due to the economic constraints, a development of cost effective and clean processes is desired. Adsorption processes has proved to be the most effective, especially for effluents with moderate and low heavy metal concentrations, as like as in printing wastewaters. Among several removal technologies, the adsorption of Zn(II) ion onto NZ, B, pure C and C with PEG 600 addition could be of great importance for the printing wastewaters purification. However, the newly designed adsorbent of the defined pore size distribution and phase structure considered as the most suitable material for Zn(II) ion removal. The values of distribution coefficient (Kd) increased with decreasing of the adsorbent amount. The Kd values depend also on the type of used adsorbent, the following increased order is obtained: NZ < B = pure C < C with PEG 600 addition. The adsorption equilibrium data of Zn(II) ion on NZ, B, pure C and C with PEG 600 were analyzed in terms of the Freundlich, Langmuir and Dubinin-Kaganer-Radushkevich (DKR) isotherm models. The characteristic parameters for each isotherms and related correlation coefficients were determined. The values of correlation coefficient (R2) indicated the following order of the isotherm models: Freundlich > Langmuir > DKR. The study also showed that the fired clay modified with PEG 600 addition has great potential

  1. Molecule-specific interactions of diatomic adsorbates at metal-liquid interfaces

    PubMed Central

    Kraack, Jan Philip; Kaech, Andres; Hamm, Peter

    2017-01-01

    Ultrafast vibrational dynamics of small molecules on platinum (Pt) layers in water are investigated using 2D attenuated total reflectance IR spectroscopy. Isotope combinations of carbon monoxide and cyanide are used to elucidate inter-adsorbate and substrate-adsorbate interactions. Despite observed cross-peaks in the CO spectra, we conclude that the molecules are not vibrationally coupled. Rather, strong substrate-adsorbate interactions evoke rapid (∼2 ps) vibrational relaxation from the adsorbate into the Pt layer, leading to thermal cross-peaks. In the case of CN, vibrational relaxation is significantly slower (∼10 ps) and dominated by adsorbate-solvent interactions, while the coupling to the substrate is negligible.

  2. Towards understanding KOH conditioning of amidoxime-based oolymer adsorbents for sequestering uranium from seawater

    DOE PAGES

    Pan, Horng-Bin; Kuo, Li-Jung; Wood, Jordana; ...

    2015-11-17

    Conditioning of polymer fiber adsorbents grafted with amidoxime and carboxylic acid groups is necessary to make the materials hydrophilic for sequestering uranium from seawater. In this paper, spectroscopic techniques were employed to study the effectiveness of the traditional KOH conditioning method (2.5% KOH at 80⁰C) on recently developed high-surface-area amidoxime-based polymer fiber adsorbents developed at Oak Ridge National Laboratory. FTIR spectra reveal that the KOH conditioning process removes the proton from the carboxylic acids and also converts the amidoxime groups to carboxylate groups in the adsorbent. With prolonged KOH treatment (>1 hr) at 80⁰C, physical damage to the adsorbent materialmore » occurs which can lead to a significant reduction in the adsorbent's uranium adsorption capability in real seawater during extended exposure times (>21 days). The physical damage to the adsorbent can be minimized by lowering KOH conditioning temperature. For the high-surface-area amidoxime-based adsorbents, 20 min of conditioning in 2.5% KOH at 80⁰C or 1 hr of conditioning in 2.5% KOH at 60⁰C appears sufficient to achieve de-protonation of the carboxylic acid with minimal harmful effects to the adsorbent material. Lastly, the use of NaOH instead of KOH can also reduce the cost of the base treatment process required for conditioning the amidoxime-based sorbents with minimal loss of adsorption capacity (≤7%).« less

  3. Towards understanding KOH conditioning of amidoxime-based oolymer adsorbents for sequestering uranium from seawater

    SciTech Connect

    Pan, Horng-Bin; Kuo, Li-Jung; Wood, Jordana; Strivens, Jonathan E.; Gill, Gary A.; Janke, Christopher James; Wai, Chien M.

    2015-11-17

    Conditioning of polymer fiber adsorbents grafted with amidoxime and carboxylic acid groups is necessary to make the materials hydrophilic for sequestering uranium from seawater. In this paper, spectroscopic techniques were employed to study the effectiveness of the traditional KOH conditioning method (2.5% KOH at 80⁰C) on recently developed high-surface-area amidoxime-based polymer fiber adsorbents developed at Oak Ridge National Laboratory. FTIR spectra reveal that the KOH conditioning process removes the proton from the carboxylic acids and also converts the amidoxime groups to carboxylate groups in the adsorbent. With prolonged KOH treatment (>1 hr) at 80⁰C, physical damage to the adsorbent material occurs which can lead to a significant reduction in the adsorbent's uranium adsorption capability in real seawater during extended exposure times (>21 days). The physical damage to the adsorbent can be minimized by lowering KOH conditioning temperature. For the high-surface-area amidoxime-based adsorbents, 20 min of conditioning in 2.5% KOH at 80⁰C or 1 hr of conditioning in 2.5% KOH at 60⁰C appears sufficient to achieve de-protonation of the carboxylic acid with minimal harmful effects to the adsorbent material. Lastly, the use of NaOH instead of KOH can also reduce the cost of the base treatment process required for conditioning the amidoxime-based sorbents with minimal loss of adsorption capacity (≤7%).

  4. Phosphorus removal from aqueous solutions using a synthesized adsorbent prepared from mineralized refuse and sewage sludge.

    PubMed

    Chen, Kaining; Zhao, Keqiang; Zhang, Houhu; Sun, Qinfang; Wu, Zhilin; Zhou, Yongmin; Zhong, Yongchao; Ke, Fan

    2013-01-01

    Mineralized refuse and sewage sludge generated from solid waste from municipal landfills and sewage treatment plants were sintered as a cost-effective adsorbent for the removal of phosphorus. Compared with the Freundlich model, phosphorus adsorption on the synthesized adsorbent, zeolite and ironstone was best described by the Langmuir model. Based on the Langmuir model, the maximum adsorption capacity of the synthesized adsorbent (9718 mg kg(-1)) was 13.7 and 25.4 times greater than those of zeolite and ironstone, respectively. The desorbability of phosphorus from the synthesized adsorbent was significantly lower than that of zeolite. Moreover, phosphorus removal using the synthesized adsorbent was more tolerant to pH fluctuations than zeolite and ironstone for the removal of phosphorus from aqueous solutions. The immobilization of phosphorus onto the synthesized adsorbent was attributed to the formation of insoluble calcium, aluminium and iron phosphorus. The heavy metal ion concentrations of the leachate of the synthesized adsorbent were negligible. The synthesized adsorbent prepared from mineralized refuse and sewage sludge was cost-effective and possessed a high adsorptive capacity for phosphorus removal from aqueous solutions.

  5. Heat transfer to the adsorbent in solar adsorption cooling device

    NASA Astrophysics Data System (ADS)

    Pilat, Peter; Patsch, Marek; Papucik, Stefan; Vantuch, Martin

    2014-08-01

    The article deals with design and construction of solar adsorption cooling device and with heat transfer problem in adsorber. The most important part of adsorption cooling system is adsorber/desorber containing adsorbent. Zeolith (adsorbent) type was chosen for its high adsorption capacity, like a coolant was used water. In adsorber/desorber occur, at heating of adsorbent, to heat transfer from heat change medium to the adsorbent. The time required for heating of adsorber filling is very important, because on it depend flexibility of cooling system. Zeolith has a large thermal resistance, therefore it had to be adapted the design and construction of adsorber. As the best shows the tube type of adsorber with double coat construction. By this construction is ensured thin layer of adsorbent and heating is quick in all volume of adsorbent. The process of heat transfer was experimentally measured, but for comparison simulated in ANSYS, too.

  6. NASA Applications of Molecular Adsorber Coatings

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin S.

    2015-01-01

    The Molecular Adsorber Coating (MAC) is a new, innovative technology that was developed to reduce the risk of molecular contamination on spaceflight applications. Outgassing from materials, such as plastics, adhesives, lubricants, silicones, epoxies, and potting compounds, pose a significant threat to the spacecraft and the lifetime of missions. As a coating made of highly porous inorganic materials, MAC offers impressive adsorptive capabilities that help capture and trap contaminants. Past research efforts have demonstrated the coating's promising adhesion performance, optical properties, acoustic durability, and thermal stability. These results advocate its use near or on surfaces that are targeted by outgassed materials, such as internal optics, electronics, detectors, baffles, sensitive instruments, thermal control coatings, and vacuum chamber test environments. The MAC technology has significantly progressed in development over the recent years. This presentation summarizes the many NASA spaceflight applications of MAC and how the coatings technology has been integrated as a mitigation tool for outgassed contaminants. For example, this sprayable paint technology has been beneficial for use in various vacuum chambers for contamination control and hardware bake-outs. The coating has also been used in small instrument cavities within spaceflight instrument for NASA missions.

  7. Factors affecting cellulose hydrolysis based on inactivation of adsorbed enzymes.

    PubMed

    Ye, Zhuoliang; Berson, R Eric

    2014-09-01

    The rate of enzymatic hydrolysis of cellulose reaction is known to decrease significantly as the reaction proceeds. Factors such as reaction temperature, time, and surface area of substrate that affect cellulose conversion were analyzed relative to their role in a mechanistic model based on first order inactivation of adsorbed cellulases. The activation energies for the hydrolytic step and inactivation step were very close in magnitude: 16.3 kcal mol(-1) for hydrolysis and 18.0 kcal mol(-1) for inactivation, respectively. Therefore, increasing reaction temperature would cause a significant increase in the inactivation rate in addition to the catalytic reaction rate. Vmax,app was only 20% or less of the value at 72 h compared to at 2h as a result of inactivation of adsorbed cellulases, suggesting prolonged hydrolysis is not an efficient way to improve cellulose hydrolysis. Hydrolysis rate increased with corresponding increases in available substrate surface binding area.

  8. Introduction of double amidoxime group by double post surface modification on poly(vinylbenzyl chloride) beads for higher amounts of organic dyes, As (V) and Cr (VI) removal.

    PubMed

    Ajmal, Muhammad; Demirci, Sahin; Uzun, Yusuf; Siddiq, Mohammad; Aktas, Nahit; Sahiner, Nurettin

    2016-05-15

    In this study, the synthesis of micron-sized poly(vinylbenzyl chloride) (p(VBC)) beads and subsequent conversion of the reactive chloromethyl groups to double amidoxime group containing moieties by post modification is reported. The prepared beads were characterized by SEM and FT-IR spectroscopy. The amidoximated p(VBC) beads were used as adsorbent for the removal of organic dyes, such as eosin y (EY) and methyl orange (MO), and heavy metals containing complex ions such as dichromate (Cr2O7(2-)) and arsenate (HAsO4(2)(-)) from aqueous media. The effect of the adsorbent dose on the percent removal, the effect of initial concentration of adsorbates on the adsorption rate and their amounts were also investigated. The Langmuir, Freundlich and Temkin adsorption isotherms were applied to the adsorption processes. The results indicated that the adsorption of both dichromate and arsenate ions obeyed the Langmuir adsorption model. Interestingly, it was found that the prepared beads were capable of removing significant amounts of arsenate and dichromate ions from tap and river (Sarıcay, Canakkale-Turkey) water.

  9. PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

    EPA Science Inventory

    Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

  10. Chitin Adsorbents for Toxic Metals: A Review

    PubMed Central

    Anastopoulos, Ioannis; Bhatnagar, Amit; Bikiaris, Dimitrios N.; Kyzas, George Z.

    2017-01-01

    Wastewater treatment is still a critical issue all over the world. Among examined methods for the decontamination of wastewaters, adsorption is a promising, cheap, environmentally friendly and efficient procedure. There are various types of adsorbents that have been used to remove different pollutants such as agricultural waste, compost, nanomaterials, algae, etc., Chitin (poly-β-(1,4)-N-acetyl-d-glucosamine) is the second most abundant natural biopolymer and it has attracted scientific attention as an inexpensive adsorbent for toxic metals. This review article provides information about the use of chitin as an adsorbent. A list of chitin adsorbents with maximum adsorption capacity and the best isotherm and kinetic fitting models are provided. Moreover, thermodynamic studies, regeneration studies, the mechanism of adsorption and the experimental conditions are also discussed in depth. PMID:28067848

  11. Monitoring by Control Technique - Activated Carbon Adsorber

    EPA Pesticide Factsheets

    Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about Activated Carbon Adsorber control techniques used to reduce pollutant emissions.

  12. IR investigations of surfaces and adsorbates

    SciTech Connect

    Gwyn Williams

    2001-12-10

    Synchrotron infrared reflection-absorption measurements on single crystal metal surfaces with adsorbates have led to the determination of many key parameters related to the bonding vibrational modes and the dynamics of adsorbates. In particular, energy couplings between electrons and adsorbate motion have been shown to be a dominant mechanism on metal surfaces. Excellent agreement has been obtained with calculations for many of the observations, and the synergy between theory and experiment has led to a deeper understanding of the roles of electrons and phonons in determining the properties of interfaces and their roles in phenomena as diverse as friction, lubrication, catalysis and adhesion. Nonetheless, as the experiments are pushed harder, to describe such effects as co-adsorbed systems, disagreements continue to challenge the theory and our comprehension also is still evolving.

  13. Hydrophobic Porous Material Adsorbs Small Organic Molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K.; Hickey, Gregory S.

    1994-01-01

    Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

  14. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, Sheldon H. D.

    1992-01-01

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases.

  15. Regenerable activated bauxite adsorbent alkali monitor probe

    SciTech Connect

    Lee, S.H.D.

    1991-01-22

    This invention relates to a regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor 5 concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC 10 exhaust gases.

  16. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, S.H.D.

    1992-12-22

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases. 6 figs.

  17. A new soil test for quantitative measurement of available and adsorbed boron

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Boron soil tests currently in use, do not extract all plant available B but are used by relating the extractable amount of B to plant B content. There is a need to accurately measure all plant available or adsorbed B because B can be toxic to plants at elevated concentrations and can cause marked y...

  18. Direct observation of the photodegradation of anthracene and pyrene adsorbed onto mangrove leaves.

    PubMed

    Wang, Ping; Wu, Tun-Hua; Zhang, Yong

    2014-01-01

    An established synchronous fluorimetry method was used for in situ investigation of the photodegradation of pyrene (PYR) and anthracene (ANT) adsorbed onto fresh leaves of the seedlings of two mangrove species, Aegiceras corniculatum (L.) Blanco (Ac) and Kandelia obovata (Ko) in multicomponent mixtures (mixture of the ANT and PYR). Experimental results indicated that photodegradation was the main transformation pathway for both ANT and PYR in multicomponent mixtures. The amount of the PAHs volatilizing from the leaf surfaces and entering the inner leaf tissues was negligible. Over a certain period of irradiation time, the photodegradation of both PYR and ANT adsorbed onto the leaves of Ac and Ko followed first-order kinetics, with faster rates being observed on Ac leaves. In addition, the photodegradation rate of PYR on the leaves of the mangrove species in multicomponent mixtures was much slower than that of adsorbed ANT. Compared with the PAHs adsorbed as single component, the photodegradation rate of ANT adsorbed in multicomponent mixtures was slower, while that of PYR was faster. Moreover, the photodegradation of PYR and ANT dissolved in water in multicomponent mixtures was investigated for comparison. The photodegradation rate on leaves was much slower than in water. Therefore, the physical-chemical properties of the substrate may strongly influence the photodegradation rate of adsorbed PAHs.

  19. Universal singularities of multilayer adsorption isotherms and determination of surface area of adsorbents

    SciTech Connect

    Aranovich, G.L.; Donohue, M.D.

    1996-07-15

    The singularity in the adsorption isotherm for macroporous and nonporous adsorbents is considered as a universal function that can be characterized with two parameters: a coefficient of proportionality, K, and an exponent, d. It is shown that the value of K is proportional to the adsorbent surface area but does not depend on the nature of the adsorbent. This leads to a new method to determine the surface area of an adsorbent, S, that is independent of the form of the adsorption isotherm at low and moderate reduced pressures. Comparison with the BET areas for nitrogen shows that the new method gives the values of S which are very close to the BET results if K = 1.47 {times} 10{sup {minus}5} mol/m{sup 2} (for nitrogen). Analysis of adsorption data for macroporous adsorbents shows that the BET isotherm gives systematic deviations and that the experimental amount adsorbed is smaller than the value predicted by the BET equation (even in the range of the best agreement with experiment). These deviations lead to systematic error in the values of S of about 43%. Using K equal to K{sub f} = 1/{sigma}N{sub A} (=1.025 {times} 10{sup {minus}5} mol/m{sup 2} for nitrogen), the authors are able to eliminate systematic error in the surface area determination. Here {sigma} is the area occupied by one molecule and N{sub A} is the Avogadro number.

  20. Direct Observation of the Photodegradation of Anthracene and Pyrene Adsorbed onto Mangrove Leaves

    PubMed Central

    Wang, Ping; Wu, Tun-Hua; Zhang, Yong

    2014-01-01

    An established synchronous fluorimetry method was used for in situ investigation of the photodegradation of pyrene (PYR) and anthracene (ANT) adsorbed onto fresh leaves of the seedlings of two mangrove species, Aegiceras corniculatum (L.) Blanco (Ac) and Kandelia obovata (Ko) in multicomponent mixtures (mixture of the ANT and PYR). Experimental results indicated that photodegradation was the main transformation pathway for both ANT and PYR in multicomponent mixtures. The amount of the PAHs volatilizing from the leaf surfaces and entering the inner leaf tissues was negligible. Over a certain period of irradiation time, the photodegradation of both PYR and ANT adsorbed onto the leaves of Ac and Ko followed first-order kinetics, with faster rates being observed on Ac leaves. In addition, the photodegradation rate of PYR on the leaves of the mangrove species in multicomponent mixtures was much slower than that of adsorbed ANT. Compared with the PAHs adsorbed as single component, the photodegradation rate of ANT adsorbed in multicomponent mixtures was slower, while that of PYR was faster. Moreover, the photodegradation of PYR and ANT dissolved in water in multicomponent mixtures was investigated for comparison. The photodegradation rate on leaves was much slower than in water. Therefore, the physical-chemical properties of the substrate may strongly influence the photodegradation rate of adsorbed PAHs. PMID:25144741

  1. Investigations Into the Reusability of Amidoxime-Based Polymeric Uranium Adsorbents

    SciTech Connect

    Kuo, Li-Jung; Gill, Gary A.; Strivens, Jonathan E.; Wood, Jordana R.; Schlafer, Nicholas J.; Wai, Chien M.; Pan, H. B.

    2016-09-28

    Significant advancements in amidoxime-based polymeric adsorbents to extract uranium from seawater are achieved in recent years. The success of uranium adsorbent development can help provide a sustainable supply of fuel for nuclear reactors. To bring down the production cost of this new technology, in addition to the development of novel adsorbents with high uranium capacity and manufacture cost, the development of adsorbent re-using technique is critical because it can further reduce the cost of the adsorbent manufacture. In our last report, the use of high concentrations of bicarbonate solution (3M KHCO3) was identified as a cost-effective, environmental friendly method to strip uranium from amidoxime-based polymeric adsorbents. This study aims to further improve the method for high recovery of uranium capacity in re-uses and to evaluate the performance of adsorbents after multiple re-use cycles. Adsorption of dissolved organic matter (DOM) on the uranium adsorbents during seawater exposure can hinder the uranium adsorption and slow down the adsorption rate. An additional NaOH rinse (0.5 M NaOH, room temperature) was applied after the 3 M KHCO3 elution to remove natural organic matter from adsorbents. The combination of 3 M KHCO3 elution and 0.5 M NaOH rinse significantly improves the recovery of uranium adsorption capacity in the re-used adsorbents. In the first re-use, most ORNL adsorbents tested achieve ~100% recovery by using 3 M KHCO3 elution + 0.5 M NaOH rinse approach, in comparison to 54% recovery when only 3 M KHCO3 elution was applied. A significant drop in capacity was observed when the adsorbents went through more than one re-use. FTIR spectra revealed that degradation of amidoxime ligands occurs during seawater exposure, and is more significant the longer the exposure time. Significantly elevated ratios of Ca/U and Mg/U in re-used adsorbents support the decrease in abundance of amidoxime ligands and increase carboxylate group from FT-IR analysis. The

  2. DBPs removal in GAC filter-adsorber.

    PubMed

    Kim, Jinkeun; Kang, Byeongsoo

    2008-01-01

    A rapid sand filter and granular activated carbon filter-adsorber (GAC FA) were compared in terms of dissolved organic carbon (DOC) and disinfection by-products (DBPs) removal. A water treatment plant (WTP) that had a high ammonia concentration and DOC in raw water, which, in turn, led to a high concentration of DBPs because of a high dose of pre-chlorination, was investigated. To remove DBPs and DOC simultaneously, a conventional rapid sand filter had been retrofitted to a GAC FA at the Buyeo WTP in Korea. The overall removal efficiency of DBPs and DOC was higher in the GAC FA than in the sand filter, as expected. Breakthrough of trihalomethanes (THMs) was noticed after 3 months of GAC FA operation, and then removal of THMs was minimal (<10%). On the other hand, the removal efficiency of five haloacetic acids (HAA(5)) in the GAC FA was better than that of THMs, though adsorption of HAA(5) decreased rapidly after 3.5 months of GAC FA operation. And then, gradual improvement (>90%) in HAA(5) removal efficiency was again observed, which could be attributed to biodegradation. At the early stage of GAC FA operation, HAA(5) removal was largely due to physical adsorption, but later on biodegradation appeared to prevail. Biodegradation of HAA(5) was significantly influenced by water temperature. Similar turbidity removal was noticed in both filters, while better manganese removal was confirmed in the sand filter rather than in the GAC FA.

  3. High performance of a unique mesoporous polystyrene-based adsorbent for blood purification

    PubMed Central

    Chen, Jian; Han, Wenyan; Chen, Jie; Zong, Wenhui; Wang, Weichao; Wang, Yue; Cheng, Guanghui; Li, Chunran; Ou, Lailiang; Yu, Yaoting

    2017-01-01

    A multi-functional polystyrene based adsorbent (NKU-9) with a unique mesoporous and a high surface area was prepared by suspension polymerization for removal of therapeutic toxins in blood purification. The adsorbent produced had an almost equal amount of mesopore distribution in the range from 2 to 50 nm. The adsorption of serum toxins with different molecular weights were examined by in vitro adsorption assays and compared with some clinical currently used adsorbents such as HA-330, Cytosorb and BL-300 which are produced by China, America and Japan, respectively. Test results indicated that the adsorption rate for pentobarbital by NKU-9 was 81.24% which is nearly as high as HA-330 (81.44%). The latter adsorbent is currently used for acute detoxification treatment in China. To reach adsorption equilibrium, NKU-9 was faster than HA-330, which implies short treatment time. For the removal of middle molecular toxins such as β2-microglobulin (98.88%), NKU-9 performed better adsorptive selectivity than Cytosorb (92.80%). In addition, NKU-9 showed high performance for the removal of albumin-bound toxins (e.g., bilirubin), and its adsorption rate for total bilirubin (80.79%) in plasma was 8.4% higher than that of anion exchange resin BL-300 which is currently used to eliminate bilirubin in clinic. Therefore, our results indicate that the newly developed adsorbent with a wide distribution and almost equal amount of mesopores is a multifunctional adsorbent for high efficient removal of serum toxins with different molecular weights which might be an excellent blood purification adsorbent especially to treat diseases that conventional medical methods are low or not efficient. PMID:28149527

  4. Aminosilica materials as adsorbents for the selective removal of aldehydes and ketones from simulated bio-oil.

    PubMed

    Drese, Jeffrey H; Talley, Anne D; Jones, Christopher W

    2011-03-21

    The fast pyrolysis of biomass is a potential route to the production of liquid biorenewable fuel sources. However, degradation of the bio-oil mixtures due to reaction of oxygenates, such as aldehydes and ketones, reduces the stability of the liquids and can impact long-term storage and shipping. Herein, solid aminosilica adsorbents are described for the selective adsorptive removal of reactive aldehyde and ketone species. Three aminosilica adsorbents are prepared through the reaction of amine-containing silanes with pore-expanded mesoporous silica. A fourth aminosilica adsorbent is prepared through the ring-opening polymerization of aziridine from pore-expanded mesoporous silica. Adsorption experiments with a representative mixture of bio-oil model compounds are presented using each adsorbent at room temperature and 45 °C. The adsorbent comprising only primary amines adsorbs the largest amount of aldehydes and ketones. The overall reactivity of this adsorbent increases with increasing temperature. Additional aldehyde screening experiments show that the reactivity of aldehydes with aminosilicas varies depending on their chemical functionality. Initial attempts to regenerate an aminosilica adsorbent by acid hydrolysis show that they can be at least partially regenerated for further use.

  5. Sewage sludge-derived materials as efficient adsorbents for removal of hydrogen sulfide.

    PubMed

    Bagreev, A; Bashkova, S; Locke, D C; Bandosz, T J

    2001-04-01

    Sewage sludge-derived materials were used as adsorbents of hydrogen sulfide from moist air. The adsorbent obtained by carbonization at 950 degrees C has a capacity twice of that of coconut-shell-based activated carbon. The capacity of the sludge-derived materials increases with increasing carbonization temperature. It is likelythatduring carbonization at 950 degrees C a mineral-like phase is formed that consists of such catalytically active metals as iron, zinc, and copper. The results obtained demonstrate that the presence of iron oxide significantly increases the capacity of commercial carbon and activated alumina. The sludge-derived adsorbents are efficient for hydrogen sulfide removal until the pore entrances are blocked with sulfur as the product of oxidation reaction. For materials in which the catalytic effect is predominant, hydrogen sulfide is adsorbed until all pores are filled with sulfur. There is also indication that chemisorption plays a significant role in the removal of hydrogen sulfide from moist air.

  6. Effect of peptide secondary structure on adsorption and adsorbed film properties on end-grafted polyethylene oxide layers.

    PubMed

    Binazadeh, M; Zeng, H; Unsworth, L D

    2014-01-01

    Poly-l-lysine (PLL), in α-helix or β-sheet configuration, was used as a model peptide for investigating the effect of secondary structures on adsorption events to poly(ethylene oxide) (PEO) modified surfaces formed using θ solvents. Circular dichroism results showed that the secondary structure of PLL persisted upon adsorption to Au and PEO modified Au surfaces. Quartz crystal microbalance with dissipation (QCM-D) was used to characterize the chemisorbed PEO layer in different solvents (θ and good solvents), as well as the sequential adsorption of PLL in different secondary structures (α-helix or β-sheet). QCM-D results suggest that chemisorption of PEO 750 and 2000 from θ solutions led to brushes 3.8 ± 0.1 and 4.5 ± 0.1 nm thick with layer viscosities of 9.2 ± 0.8 and 4.8 ± 0.5 cP, respectively. The average number of H2O per ethylene oxides, while in θ solvent, was determined as ~0.9 and ~1.2 for the PEO 750 and 2000 layers, respectively. Upon immersion in good solvent (as used for PLL adsorption experiments), the number of H2O per ethylene oxides increased to ~1.5 and ~2.0 for PEO 750 and 2000 films, respectively. PLL adsorbed masses for α-helix and β-sheet on Au sensors was 231 ± 5 and 1087 ± 14 ng cm(-2), with layer viscosities of 2.3 ± 0.1 and 1.2 ± 0.1 cP, respectively; suggesting that the α-helix layer was more rigid, despite a smaller adsorbed mass, than that of β-sheet layers. The PEO 750 layer reduced PLL adsorbed amounts to ~10 and 12% of that on Au for α-helices and β-sheets respectively. The PLL adsorbed mass to PEO 2000 layers dropped to ~12% and 4% of that on Au, for α-helix and β-sheet respectively. No significant differences existed for the viscosities of adsorbed α-helix and β-sheet PLL on PEO surfaces. These results provide new insights into the fundamental understanding of the effects of secondary structures of peptides and proteins on their surface adsorption.

  7. Black Molecular Adsorber Coatings for Spaceflight Applications

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

    2014-01-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  8. Size selective hydrophobic adsorbent for organic molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Hickey, Gregory S. (Inventor)

    1997-01-01

    The present invention relates to an adsorbent formed by the pyrolysis of a hydrophobic silica with a pore size greater than 5 .ANG., such as SILICALITE.TM., with a molecular sieving polymer precursor such as polyfurfuryl alcohol, polyacrylonitrile, polyvinylidene chloride, phenol-formaldehyde resin, polyvinylidene difluoride and mixtures thereof. Polyfurfuryl alcohol is the most preferred. The adsorbent produced by the pyrolysis has a silicon to carbon mole ratio of between about 10:1 and 1:3, and preferably about 2:1 to 1:2, most preferably 1:1. The pyrolysis is performed as a ramped temperature program between about 100.degree. and 800.degree. C., and preferably between about 100.degree. and 600.degree. C. The present invention also relates to a method for selectively adsorbing organic molecules having a molecular size (mean molecular diameter) of between about 3 and 6 .ANG. comprising contacting a vapor containing the small organic molecules to be adsorbed with the adsorbent composition of the present invention.

  9. Membrane Perturbation Induced by Interfacially Adsorbed Peptides

    PubMed Central

    Zemel, Assaf; Ben-Shaul, Avinoam; May, Sylvio

    2004-01-01

    The structural and energetic characteristics of the interaction between interfacially adsorbed (partially inserted) α-helical, amphipathic peptides and the lipid bilayer substrate are studied using a molecular level theory of lipid chain packing in membranes. The peptides are modeled as “amphipathic cylinders” characterized by a well-defined polar angle. Assuming two-dimensional nematic order of the adsorbed peptides, the membrane perturbation free energy is evaluated using a cell-like model; the peptide axes are parallel to the membrane plane. The elastic and interfacial contributions to the perturbation free energy of the “peptide-dressed” membrane are evaluated as a function of: the peptide penetration depth into the bilayer's hydrophobic core, the membrane thickness, the polar angle, and the lipid/peptide ratio. The structural properties calculated include the shape and extent of the distorted (stretched and bent) lipid chains surrounding the adsorbed peptide, and their orientational (C-H) bond order parameter profiles. The changes in bond order parameters attendant upon peptide adsorption are in good agreement with magnetic resonance measurements. Also consistent with experiment, our model predicts that peptide adsorption results in membrane thinning. Our calculations reveal pronounced, membrane-mediated, attractive interactions between the adsorbed peptides, suggesting a possible mechanism for lateral aggregation of membrane-bound peptides. As a special case of interest, we have also investigated completely hydrophobic peptides, for which we find a strong energetic preference for the transmembrane (inserted) orientation over the horizontal (adsorbed) orientation. PMID:15189858

  10. Adsorbent catalytic nanoparticles and methods of using the same

    DOEpatents

    Slowing, Igor Ivan; Kandel, Kapil

    2017-01-31

    The present invention provides an adsorbent catalytic nanoparticle including a mesoporous silica nanoparticle having at least one adsorbent functional group bound thereto. The adsorbent catalytic nanoparticle also includes at least one catalytic material. In various embodiments, the present invention provides methods of using and making the adsorbent catalytic nanoparticles. In some examples, the adsorbent catalytic nanoparticles can be used to selectively remove fatty acids from feedstocks for biodiesel, and to hydrotreat the separated fatty acids.

  11. A study of the alumina-silica gel adsorbent for the removal of silicic acid from geothermal water: increase in adsorption capacity of the adsorbent due to formation of amorphous aluminosilicate by adsorption of silicic acid.

    PubMed

    Yokoyama, Takushi; Ueda, Akira; Kato, Koichi; Mogi, Katsumi; Matsuo, Shorin

    2002-08-01

    Two kinds of adsorbents (Si adsorbent and Al adsorbent) for the removal of silicic acid from geothermal water to retard the formation of silica scales were prepared using silicic acid contained in geothermal water. The Si adsorbent was prepared by evaporating geothermal water, and the Al adsorbent was prepared by evaporating geothermal water after the addition of aluminum chloride. The specific surface area of the Si adsorbent was small and it's adsorption capacity of silicic acid was low. Although the specific surface area of the Al adsorbent was also small, it was significantly increased by the adsorption of silicic acid and it's adsorption capacity was high. Based on the change in the local structure of aluminum ion by the adsorption of silicic acid, the Al adsorbent was considered to be silica particles covered with crystalline aluminum hydroxide. Moreover, it was concluded that the increase in the specific surface area of the Al adsorbent and the decrease in the zeta potential were due to the formation of an amorphous aluminosilicate with a large surface area and a negative charge (one 4-coordinated Al) by the reaction between aluminum ions and silicic acids.

  12. Bayer Electrofilter Fines as Potential Se(VI) Adsorbents

    NASA Astrophysics Data System (ADS)

    Ayala, Julia; Fernández, Begoña

    2015-11-01

    Removal of Se(VI) from an aqueous solution under different conditions was investigated using Bayer electrofilter fines (BEFs), a waste from alumina production, as an adsorbent. Adsorption selenate was studied using batch adsorption experiments as a function of pH (2-12), contact time (0.08-30 h), adsorbent concentration (4-80 g/L), initial selenium concentration (5-203 mg/L), and ionic strength (0-0.1 M NaCl). The results showed that adsorption was significantly affected by pH Se(VI) having the highest affinity for BEFs at pH 3. Sorption Se(VI) reached equilibrium in 4 h. Increasing ionic strength decreased selenate sorption. The adsorption of Se(VI) onto BEFs was found to fit the Langmuir isotherm. Maximum selenium uptake values were calculated as 2.3613 mg/g and 1.5608 mg/g when using adsorbent concentrations of 20 g/L and 40 g/L, respectively.

  13. Infrared Analysis Of Enzymes Adsorbed Onto Model Surfaces

    NASA Astrophysics Data System (ADS)

    Story, Gloria M.; Rauch, Deborah S.; Brode, Philip F.; Marcott, Curtis A.

    1989-12-01

    The adsorption of the enzymes, subtilisin BPN' and lysozyme, onto model surfaces was examined using attenuated total reflectance (ATR) infrared (IR) spectroscopy. Using a cylindrical internal reflection (CIRcle) cell with a Germanium (Ge) internal reflection element (IRE), model hydrophilic surfaces were made by plasma cleaning the IRE and model hydrophobic surfaces were made by precoating the IRE with a thin film of polystyrene. Gas chromatography (GC)-IR data collection software was used to monitor adsorption kinetics during the first five minutes after injection of the enzyme into the CIRcle cell. It was found that for both lysozyme and BPN', most of the enzyme that was going to adsorb onto the model surface did so within ten seconds after injection. Nearly an order-of-magnitude more BPN' adsorbed on the hydrophobic Ge surface than the hydrophilic one, while lysozyme adsorbed somewhat more strongly to the hydrophilic Ge surface. Overnight, the lysozyme layer continued to increase in thickness, while BPN' maintained its initial coverage. The appearance of carboxylate bands in some of the adsorbed BPN' spectra suggests the occurrence of peptide bond hydrolysis. A Au/Pd coating on the CIRcle cell o-rings had a significant effect on the adsorption of BPN'. (This coating was applied in an attempt to eliminate interfering Teflon absorption bands.) An apparent electrochemical reaction occurred, involving BPN', Ge, Au/Pd, and the salt solution used to stabilize BPN'. The result of this reaction was enhanced adsorption of the enzyme around the coated o-rings, etching of the Ge IRE at the o-ring site, and some autolysis of the enzyme. No such reaction was observed with lysozyme.

  14. Time Resolved Studies Of Adsorbed Species

    NASA Astrophysics Data System (ADS)

    Howard, J.; Nicol, J. M.

    1985-12-01

    A time-resolved Fourier transform IR study of ethyne adsorbed on ZnNaA zeolite yields results very different from those reported for related systems. Initially two species (A and B) are formed by the interaction of C2H2 with the cations. Whereas species A (π-bonded C2H2) was found to be removed immediately on evacuation, species B (probably Zn-acetylide) was not fully removed after 60 mins evacuation. In the presence of the gas phase, bands due to Species A decreased slowly in intensity as new bands due to adsorbed ethanal were observed.

  15. Adsorption and Desorption of Carbon Dioxide and Water Mixtures on Synthetic Hydrophobic Carbonaceous Adsorbents

    NASA Technical Reports Server (NTRS)

    Finn, John E.; Harper, Lynn D. (Technical Monitor)

    1994-01-01

    Several synthetic carbonaceous adsorbents produced through pyrolysis of polymeric materials are available commercially. Some appear to have advantages over activated carbon for certain adsorption applications. In particular, they can have tailored hydrophobicities that are significantly greater than that of activated carbon, while moderately high surfaces areas are retained. These sorbents are being investigated for possible use in removing trace contaminants and excess carbon dioxide from air in closed habitats, plant growth chambers, and other applications involving purification of humid gas streams. We have analyzed the characteristics of a few of these adsorbents through adsorption and desorption experiments and standard characterization techniques. This paper presents pure and multicomponent adsorption data collected for carbon dioxide and water on two synthetic carbonaceous adsorbents having different hydrophobicities and capillary condensation characteristics. The observations are interpreted through consideration of the pore structure and surface chemistry of the solids and interactions between adsorbed carbon dioxide, water, and the solvent gas.

  16. Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry

    NASA Astrophysics Data System (ADS)

    Silber, David; Kowalski, Piotr M.; Traeger, Franziska; Buchholz, Maria; Bebensee, Fabian; Meyer, Bernd; Wöll, Christof

    2016-09-01

    Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO2(110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO2(110) surface.

  17. Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry.

    PubMed

    Silber, David; Kowalski, Piotr M; Traeger, Franziska; Buchholz, Maria; Bebensee, Fabian; Meyer, Bernd; Wöll, Christof

    2016-09-30

    Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO2(110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO2(110) surface.

  18. Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry

    PubMed Central

    Silber, David; Kowalski, Piotr M.; Traeger, Franziska; Buchholz, Maria; Bebensee, Fabian; Meyer, Bernd; Wöll, Christof

    2016-01-01

    Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO2(110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO2(110) surface. PMID:27686286

  19. Graphene protected surface state on Ir(111) with adsorbed lithium

    NASA Astrophysics Data System (ADS)

    Lazic, Predrag; Pervan, Petar; Petrovic, Marin; Srut-Rakic, Iva; Pletikosic, Ivo; Kralj, Marko; Milun, Milorad; Valla, Tonica

    It is well known that electronic surface states (SS) get strongly perturbed upon the chemical adsorption of very small amount of adsorbates. Adsorption of lithium atoms on Ir(111) is no exception to that rule. Iridium SS gets strongly perturbed and is practically eradicated - it can not be seen as a sharp peak in the ARPES measurement. However, if the system is prepared with graphene on top of Ir/Li system, the iridium SS reappears. We present a combined experimental and theoretical study of the described system. Using the density functional theory calculations for large unit cells with disordered lithium atoms geometries on the (111) surface of iridium we were able to reproduce the results of the ARPES measurements - showing clearly that the SS signal is strongly suppressed when lithium is adsorbed, while it is almost unchanged when lithium is intercalated (i.e. with graphene on top of it). Looking at the projected density of states we constructed a rather simple model explaining this behavior which seems to be general.

  20. From illite/smectite clay to mesoporous silicate adsorbent for efficient removal of chlortetracycline from water.

    PubMed

    Wang, Wenbo; Tian, Guangyan; Zong, Li; Zhou, Yanmin; Kang, Yuru; Wang, Qin; Wang, Aiqin

    2017-01-01

    A series of mesoporous silicate adsorbents with superior adsorption performance for hazardous chlortetracycline (CTC) were sucessfully prepared via a facile one-pot hydrothermal reaction using low-cost illite/smectite (IS) clay, sodium silicate and magnesium sulfate as the starting materials. In this process, IS clay was "teared up" and then "rebuilt" as new porous silicate adsorbent with high specific surface area of 363.52m(2)/g (about 8.7 folds higher than that of IS clay) and very negative Zeta potential (-34.5mV). The inert SiOSi (Mg, Al) bonds in crystal framework of IS were broken to form Si(Al) O(-) groups with good adsorption activity, which greatly increased the adsorption sites served for holding much CTC molecules. Systematic evaluation on adsorption properties reveals the optimal silicate adsorbent can adsorb 408.81mg/g of CTC (only 159.7mg/g for raw IS clay) and remove 99.3% (only 46.5% for raw IS clay) of CTC from 100mg/L initial solution (pH3.51; adsorption temperature 30°C; adsorbent dosage, 3g/L). The adsorption behaviors of CTC onto the adsorbent follows the Langmuir isotherm model, Temkin equation and pseudo second-order kinetic model. The mesopore adsorption, electrostatic attraction and chemical association mainly contribute to the enhanced adsorption properties. As a whole, the high-efficient silicate adsorbent could be candidates to remove CTC from the wastewater with high amounts of CTC.

  1. Catalase-like activity studies of the manganese(II) adsorbed zeolites

    NASA Astrophysics Data System (ADS)

    ćiçek, Ekrem; Dede, Bülent

    2013-12-01

    Preparation of manganese(II) adsorbed on zeolite 3A, 4A, 5A. AW-300, ammonium Y zeolite, organophilic, molecular sieve and catalase-like enzyme activity of manganese(II) adsorbed zeolites are reported herein. Firstly zeolites are activated at 873 K for two hours before contact manganese(II) ions. In order to observe amount of adsorption, filtration process applied for the solution. The pure zeolites and manganese(II) adsorbed zeolites were analysed by FT-IR. As a result according to the FT-IR spectra, the incorporation of manganese(II) cation into the zeolite structure causes changes in the spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino and silicooxygen tetrahedral rings in the zeolite structure. Furthermore, the catalytic activities of the Mn(II) adsorbed zeolites for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The Mn(II) adsorbed zeolites display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity.

  2. Desorption of isopropyl alcohol from adsorbent with non-thermal plasma.

    PubMed

    Shiau, Chen Han; Pan, Kuan Lun; Yu, Sheng Jen; Yan, Shaw Yi; Chang, Moo Been

    2016-11-24

    Effective desorption of isopropyl alcohol (IPA) from adsorbents with non-thermal plasma is developed. In this system, IPA is effectively adsorbed with activated carbon while dielectric barrier discharge is applied to replace the conventional thermal desorption process to achieve good desorption efficiency, making the treatment equipment smaller in size. Various adsorbents including molecular sieves and activated carbon are evaluated for IPA adsorption capacity. The results indicate that BAC has the highest IPA adsorption capacity (280.31 mg IPA/g) under the operating conditions of room temperature, IPA of 400 ppm, and residence time of 0.283 s among 5 adsorbents tested. For the plasma desorption process, the IPA selectivity of 89% is achieved with BAC as N2 is used as desorbing gas. In addition, as air or O2 is used as desorbing gas, the IPA desorption concentration is reduced, because air and O2 plasmas generate active species to oxidize IPA to form acetone, CO2, and even CO. Furthermore, the results of the durability test indicate that the amount of IPA desorbed increases with increasing desorption times and plasma desorption process has a higher energy efficiency if compared with thermal desorption. Overall, this study indicates that non-thermal plasma is a viable process for removing VOCs to regenerate adsorbent.

  3. Utilization of recycled charcoal as a thermal source and adsorbent for the treatment of PCDD/Fs contaminated sediment.

    PubMed

    Zhao, Long; Hou, Hong; Iwasaki, Kanae; Terada, Akihiko; Hosomi, Masaaki

    2012-07-30

    A novel heat treatment process in which charcoal was used as both a thermal source and an adsorbent was investigated as a low-cost method for removal of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from solids. Three laboratory scale experiments involving various ratios of charcoal to contaminated sediment and air superficial velocities were performed. The results indicated that the total and toxic equivalency quantities (TEQ) concentrations of PCDD/Fs decreased significantly in the treated sediment of all runs with removal efficiencies greater than 96% and 90%, which resulted in residual concentrations below the Japanese standard limit of 0.15ng-TEQg(-1). The charcoal/contaminated sediment ratio and air superficial velocity were determinant factors controlling the PCDD/Fs concentrations and homologue profiles in effluent. As the air superficial velocity increased and charcoal/contaminated sediment ratio decreased, more PCDD/Fs were released from the sediment as fly ash, making them less likely to remain in the treated sediment. These phenomena were likely a result of the vapor pressure of PCDD/Fs, contact time with effluent gas and amount of PCDD/Fs adsorbed by charcoal. The developed process would promise an alternative to a conventional remediation process for PCDD/Fs contaminated solids.

  4. Preparation and Characterization of Chitosan/Feldspar Biohybrid as an Adsorbent: Optimization of Adsorption Process via Response Surface Modeling

    PubMed Central

    Yazdani, Maryam; Bahrami, Hajir; Arami, Mokhtar

    2014-01-01

    Chitosan/feldspar biobased beads were synthesized, characterized, and tested for the removal of Acid Black 1 dye from aquatic phases. A four-factor central composite design (CCD) accompanied by response surface modeling (RSM) and optimization was used to optimize the dye adsorption by the adsorbent (chitosan/feldspar composite) in 31 different batch experiments. Independent variables of temperature, pH, initial dye concentration, and adsorbent dose were used to change to coded values. To anticipate the responses, a quadratic model was applied. Analysis of variance (ANOVA) tested the significance of the process factors and their interactions. The adequacy of the model was investigated by the correlation between experimental and predicted data of the adsorption and the calculation of prediction errors. The results showed that the predicted maximum adsorption amount of 21.63 mg/g under the optimum conditions (pH 3, temperature 15°C, initial dye concentration 125 mg/L, and dose 0.2 g/50 mL) was close to the experimental value of 19.85 mg/g. In addition, the results of adsorption behaviors of the dye illustrated that the adsorption process followed the Langmuir isotherm model and the pseudo-second-order kinetic model. Langmuir sorption capacity was found to be 17.86 mg/g. Besides, thermodynamic parameters were evaluated and revealed that the adsorption process was exothermic and favourable. PMID:24587722

  5. In Situ Investigation the Photolysis of the PAHs Adsorbed on Mangrove Leaf Surfaces by Synchronous Solid Surface Fluorimetry

    PubMed Central

    Wang, Ping; Wu, Tun-Hua; Zhang, Yong

    2014-01-01

    An established synchronous solid surface fluorimetry (S-SSF) was utilized for in situ study the photolysis processes of anthracene (An) and pyrene (Py) adsorbed on the leaf surfaces of Kandelia obovata seedlings (Ko) and Aegiceras corniculata (L.) Blanco seedlings (Ac). Experimental results demonstrated that the photolysis of An and Py adsorbed on the leaf surfaces of two mangrove species under the laboratory conditions, followed first-order kinetics with their photolysis rates in the order of Ac>Ko. In addition, with the same amount of substances, the photolysis rate of An adsorbed on the same mangrove leaf surfaces was much faster than the adsorbed Py. In order to investigate further, the photolysis processes of An and Py in water were also studied for comparison. And the photolysis of An and Py in water also followed first-order kinetics. Moreover, for the same initial amount, the photolysis rate of the PAH in water was faster than that adsorbed on the leaf surfaces of two mangrove species. Therefore, photochemical behaviors of PAHs were dependent not only on their molecular structures but also the physical-chemical properties of the substrates on which they are adsorbed. PMID:24404158

  6. Production of scallop shell nanoparticles by mechanical grinding as a formaldehyde adsorbent

    NASA Astrophysics Data System (ADS)

    Yamanaka, Shinya; Suzuma, Akifumi; Fujimoto, Toshiyuki; Kuga, Yoshikazu

    2013-04-01

    Scallop shells, which are a waste product in the seafood industry, are disposed more than 200,000 ton per year in Hokkaido, Japan. We report effective uses and simple application for discarded shells as a formaldehyde adsorbent. The adsorption performance of scallop shells to remove formaldehyde vapor is investigated. Planetary ball milling under dry conditions and subsequent water addition realize shells with a crystallite size (35-90 nm) and equivalent size of the specific surface area (41-191 nm) in the nanometer range. The comminution properties of the scallop shells, especially the grinding limit, are estimated via a semi-theoretical consideration for the grinding limit. Additionally, the adsorbed amount of gaseous formaldehyde using a self-designed adsorption line is estimated. The nanosized scallop shells exhibit an excellent adsorption performance rather than the feed shell, and the adsorbed amount is positively correlated with the specific surface area of the shell. Hence, scallop shells have potential to adsorb volatile organic compounds.

  7. From MDF and PB wastes to adsorbents for the removal of pollutants

    NASA Astrophysics Data System (ADS)

    Gomes, J. A. F. L.; Azaruja, B. A.; Mourão, P. A. M.

    2016-09-01

    The production of activated carbons in powder and monolith forms, by physical activation with CO2, with specific surface areas between 804 and 1469 m2 g-1, porous volume between 0.33 and 0.59 cm3 g-1, with basic nature (PZC ∼ 9.6-10.6) was achieved in our lab, from medium density fibreboard (MDF) and particleboard (PB), engineered wood composites wastes. These highly porous adsorbents were applied in kinetic and equilibrium adsorption studies, in batch and dynamic modes, in powder and monolith forms, of specific adsorptives, considered pollutants, namely phenol (P), p-nitrophenol (PNP) and neutral red (NR). In batch the maximum adsorbed amount was 267, 162 and 92 mg g-1, for PNP, P and NR, respectively. The application of different kinetic models (pseudo-first order, pseudo-second order and intraparticle diffusion model) leads to a better knowledge of the adsorption mechanisms of those adsorptives. The results obtained in the kinetic and equilibrium tests show that the combination of the structural features and the surface chemistry nature of the adsorbents, with the adsorptives properties, establish the kinetic performance, the type and amount adsorbed for each system. This work confirms the potential of these types of wastes in the production of activated carbons and its application in adsorption from liquid phase.

  8. Methyl red removal from water by iron based metal-organic frameworks loaded onto iron oxide nanoparticle adsorbent

    NASA Astrophysics Data System (ADS)

    Dadfarnia, S.; Haji Shabani, A. M.; Moradi, S. E.; Emami, S.

    2015-03-01

    The objective followed by this research is the synthesis of iron based metal organic framework loaded on iron oxide nanoparticles (Fe3O4@MIL-100(Fe)) and the study of its capability for the removal of methyl red. Effective parameters in the selection of a new adsorbent, i.e. adsorption capacity, thermodynamics, and kinetics were investigated. All the studies were carried out in batch experiments. Removal of methyl red from aqueous solutions varied with the amount of adsorbent, methyl red contact time, initial concentration of dye, adsorbent dosage, and solution pH. The capability of the synthesized adsorbent in the removal of methyl red was compared with the metal organic framework (MIL-100(Fe)) and iron oxide nanoparticles. The results show that Fe3O4@MIL-100(Fe) nanocomposite exhibits an enhanced adsorption capacity.

  9. Dynamic analysis of a closed-cycle solar adsorption refrigerator using two adsorbent-adsorbate pairs

    SciTech Connect

    Hajji, A. ); Worek, W. ); Lavan, Z. )

    1991-05-01

    In this paper a dynamic analysis of a closed-cycle, solar adsorption refrigerator is presented. The instantaneous and daily system performance are studied using two adsorbent-adsorbate pairs, Zeolite 13X-Water and Chabazite-Methanol. The effect of design and operating parameters, including inert material thermal capacitance, matrix porosity, and evaporation and condenser temperatures on the solar and cycle coefficients of performance are evaluated.

  10. Contaminant removal from enclosed atmospheres by regenerable adsorbents

    NASA Technical Reports Server (NTRS)

    Goldsmith, R. L.; Mcnulty, K. J.; Freedland, G. M.; Turk, A.; Nwankwo, J.

    1974-01-01

    A system for removing contaminants from spacecraft atmospheres was studied, which utilizes catalyst-impregnated activated carbon followed by in-situ regeneration by low-temperature catalytic oxidation of the adsorbed contaminants. Platinum was deposited on activated carbon by liquid phase impregnation with chloroplatinic acid, followed by drying and high-temperature reduction. Results were obtained for the seven selected spacecraft contaminants by means of three experimental test systems. The results indicate that the contaminants could be removed by oxidation with very little loss in adsorptive capacity. The advantages of a catalyst-impregnated carbon for oxidative regeneration are found to be significant enough to warrent its use.

  11. Characterization and testing of amidoxime-based adsorbent materials to extract uranium from natural seawater

    SciTech Connect

    Kuo, Li-Jung; Janke, Christopher James; Wood, Jordana; Strivens, Jonathan E.; Gill, Gary

    2015-11-19

    Extraction of uranium (U) from seawater for use as a nuclear fuel is a significant challenge due to the low concentration of U in seawater (~3.3 ppb) and difficulties to selectively extract U from the background of major and trace elements in seawater. The Pacific Northwest National Laboratory (PNNL) s Marine Sciences Laboratory (MSL) has been serving as a marine test site for determining performance characteristics (adsorption capacity, adsorption kinetics, and selectivity) of novel amidoxime-based polymeric adsorbents developed at Oak Ridge National Laboratory (ORNL) under natural seawater exposure conditions. This report describes the performance of three formulations (38H, AF1, AI8) of amidoxime-based polymeric adsorbent produced at ORNL in MSL s ambient seawater testing facility. The adsorbents were produced in two forms, fibrous material (40-100 mg samples) and braided material (5-10 g samples), exposed to natural seawater using flow-through columns and recirculating flumes. All three formulations demonstrated high 56 day uranium adsorption capacity (>3 gU/kg adsorbent). The AF1 formulation had the best uranium adsorption performance, with 56-day capacity of 3.9 g U/kg adsorbent, saturation capacity of 5.4 g U/kg adsorbent, and ~25 days half-saturation time. The two exposure methods, flow-through columns and flumes were demonstrated to produce similar performance results, providing confidence that the test methods were reliable, that scaling up from 10 s of mg quantities of exposure in flow-through columns to gram quantities in flumes produced similar results, and that the manufacturing process produces a homogenous adsorbent. Adsorption kinetics appear to be element specific, with half-saturation times ranging from minutes for the major cations in seawater to 8-10weeks for V and Fe. Reducing the exposure time provides a potential pathway to improve the adsorption capacity of U by reducing the V/U ratio on the adsorbent.

  12. Characterization and Testing of Amidoxime-Based Adsorbent Materials to Extract Uranium from Natural Seawater

    SciTech Connect

    Kuo, Li-Jung; Janke, Christopher J.; Wood, Jordana R.; Strivens, Jonathan E.; Das, Sadananda; Oyola, Yatsandra; Mayes, Richard T.; Gill, Gary A.

    2016-04-20

    Extraction of uranium (U) from seawater for use as a nuclear fuel is a significant challenge due to the low concentration of U in seawater (~3.3 ppb) and difficulties to selectively extract U from the background of major and trace elements in seawater. The Pacific Northwest National Laboratory (PNNL)’s Marine Sciences Laboratory (MSL) has been serving as a marine test site for determining performance characteristics (adsorption capacity, adsorption kinetics, and selectivity) of novel amidoxime-based polymeric adsorbents developed at Oak Ridge National Laboratory (ORNL) under natural seawater exposure conditions. This manuscript describes the performance of three formulations (38H, AF1, AI8) of amidoxime-based polymeric adsorbents produced at ORNL in MSL’s ambient seawater testing facility. The adsorbents were produced in two forms, fibrous material (40-100 mg samples) and braided material (5-10 g samples), and exposed to natural seawater using flow-through columns and recirculating flumes. All three formulations demonstrated high 56 day uranium adsorption capacity (>3 g U/kg adsorbent). The AF1 formulation had the best uranium adsorption performance, with a 56 day capacity of 3.9 g U/ kg adsorbent, a saturation capacity of 5.4 g U/kg adsorbent, and ~25 days half-saturation time. The two exposure methods, flowthrough columns and flumes, were demonstrated to produce similar performance results, providing confidence that the test methods were reliable, that scaling up from 10’s of mg quantities of exposure in flow-through columns to gram quantities in flumes produced similar results, and confirm that the manufacturing process produces a homogeneous adsorbent. Adsorption kinetics appear to be element specific, with half-saturation times ranging from minutes for the major cations in seawater, to 8-10 weeks for V and Fe. Reducing the exposure time provides a potential pathway to improve the adsorption capacity of U by reducing the V/U ratio on the adsorbent.

  13. Low-cost magnetic adsorbent for As(III) removal from water: adsorption kinetics and isotherms.

    PubMed

    Kango, Sarita; Kumar, Rajesh

    2016-01-01

    Magnetite nanoparticles as adsorbent for arsenic (As) were coated on sand particles. The coated sand was used for the removal of highly toxic element 'As(III)' from drinking water. Here, batch experiments were performed with the variation of solution pH, adsorbent dose, contact time and initial arsenic concentration. The adsorbent showed significant removal efficiency around 99.6 % for As(III). Analysis of adsorption kinetics revealed that the adsorbent follows pseudo-second-order kinetics model showing R (2) = 0.999, whereas for pseudo-first-order kinetics model, the value of R (2) was 0.978. In the case of adsorption equilibrium, the data is well fitted with Langmuir adsorption isotherm model (R (2) > 0.99), indicating monolayer adsorption of As(III) on the surface of adsorbent. The existence of commonly present ions in water influences the removal efficiency of As(III) minutely in the following order PO4 (3-) > HCO3 (-) > Cl(-) > SO4 (2-). The obtained adsorbent can be used to overcome the problem of water filtration in rural areas. Moreover, as the nano-magnetite is coated on the sand, it avoids the problem of extraction of nanoparticles from treated water and can easily be removed by a simple filtration process.

  14. Role of air bubbles overlooked in the adsorption of perfluorooctanesulfonate on hydrophobic carbonaceous adsorbents.

    PubMed

    Meng, Pingping; Deng, Shubo; Lu, Xinyu; Du, Ziwen; Wang, Bin; Huang, Jun; Wang, Yujue; Yu, Gang; Xing, Baoshan

    2014-12-02

    Hydrophobic interaction has been considered to be responsible for adsorption of perfluorooctanesulfonate (PFOS) on the surface of hydrophobic adsorbents, but the long C-F chain in PFOS is not only hydrophobic but also oleophobic. In this study, for the first time we propose that air bubbles on the surface of hydrophobic carbonaceous adsorbents play an important role in the adsorption of PFOS. The level of adsorption of PFOS on carbon nanotubes (CNTs), graphite (GI), graphene (GE), and powdered activated carbon (PAC) decreases after vacuum degassing. Vacuum degassing time and pressure significantly affect the removal of PFOS by these adsorbents. After vacuum degassing at 0.01 atm for 36 h, the extent of removal of PFOS by the pristine CNTs and GI decreases 79% and 74%, respectively, indicating the main contribution of air bubbles to PFOS adsorption. When the degassed solution is recontacted with air during the adsorption process, the removal of PFOS recovers to the value obtained without vacuum degassing, further verifying the key role of air bubbles in PFOS adsorption. By theoretical calculation, the distribution of PFOS in air bubbles on the adsorbent surfaces is discussed, and a new schematic sorption model of PFOS on carbonaceous adsorbents in the presence of air bubbles is proposed. The accumulation of PFOS at the interface of air bubbles on the adsorbents is primarily responsible for its adsorption, providing a new mechanistic insight into the transport, fate, and removal of PFOS.

  15. Activity of catalase adsorbed to carbon nanotubes: effects of carbon nanotube surface properties.

    PubMed

    Zhang, Chengdong; Luo, Shuiming; Chen, Wei

    2013-09-15

    Nanomaterials have been studied widely as the supporting materials for enzyme immobilization. However, the interactions between enzymes and carbon nanotubes (CNT) with different morphologies and surface functionalities may vary, hence influencing activities of the immobilized enzyme. To date how the adsorption mechanisms affect the activities of immobilized enzyme is not well understood. In this study the adsorption of catalase (CAT) on pristine single-walled carbon nanotubes (SWNT), oxidized single-walled carbon nanotubes (O-SWNT), and multi-walled carbon nanotubes (MWNT) was investigated. The adsorbed enzyme activities decreased in the order of O-SWNT>SWNT>MWNT. Fourier transforms infrared spectroscopy (FTIR) and circular dichrois (CD) analyses reveal more significant loss of α-helix and β-sheet of MWNT-adsorbed than SWNT-adsorbed CAT. The difference in enzyme activities between MWNT-adsorbed and SWNT-adsorbed CAT indicates that the curvature of surface plays an important role in the activity of immobilized enzyme. Interestingly, an increase of β-sheet content was observed for CAT adsorbed to O-SWNT. This is likely because as opposed to SWNT and MWNT, O-SWNT binds CAT largely via hydrogen bonding and such interaction allows the CAT molecule to maintain the rigidity of enzyme structure and thus the biological function.

  16. Effects of dissolved organic matter on adsorbed Fe(II) reactivity for the reduction of 2-nitrophenol in TiO2 suspensions.

    PubMed

    Zhu, Zhenke; Tao, Liang; Li, Fangbai

    2013-09-01

    Dissolved organic matter (DOM) is widespread in aquatic and terrestrial environments. Iron is the most abundant transition metal in the Earth's crust. The biogeochemistry of iron and the strength of Fe(II) as a reducing agent while adsorbed on minerals are affected by DOM. This study investigated the effects of Fe(II)/DOM interactions on the reduction of 2-nitrophenol (2-NP) in TiO2 suspensions. Kinetic measurements demonstrated that rates (k) of 2-NP reduction by adsorbed Fe(II) species are affected by adding DOM (denoted O-DOM), and the obtained k values under the impact of the Fe(II)/DOM interaction with different molecular weight DOM fractions [including MW<3500Da (L-DOM), 350014000Da (H-DOM)] showed significant differences. The enhanced rates of 2-NP reduction contributed to increases in the amount of adsorbed Fe(II) species and negative shifts in peak oxidation potential values (EP) in CV tests. For different molecular weight DOM fractions, increases in k (O-DOMadsorbed Fe(II) and the lower EP values. In addition, the ETC values were slightly higher in the TiO2 suspension containing the H-DOM fraction as compared the other two DOM fractions, which would further enhance the reduction rate of 2-NP. These findings promote a general understanding of Fe(II)/DOM interactions and their impact on the fate of contaminants in actual subsurface environments.

  17. Heterogeneous Reactions of Surface-Adsorbed Catechol: A Comparison of Tropospheric Aerosol Surrogates

    NASA Astrophysics Data System (ADS)

    Hinrichs, R. Z.; Woodill, L. A.

    2009-12-01

    Surface-adsorbed organics can alter the chemistry of tropospheric solid-air interfaces, such as aerosol and ground level surfaces, thereby impacting photochemical cycles and altering aerosol properties. The nature of the surface can also influence the chemistry of the surface-adsorbed organic. We employed diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to monitor the adsorption of gaseous catechol on several tropospheric aerosol surrogates and to investigate the subsequent reactivity of adsorbed-catechol with nitrogen dioxide and, in separate preliminary experiments, ozone. Graphite, kaolinite, and sodium halide (NaF, NaCl, NaBr) powders served as carbonaceous, mineral and sea salt aerosol surrogates, respectively. Broad OH stretching bands for adsorbed catechol shifted to lower wavenumber with peak frequencies following the trend NaBr > NaCl > NaF ≈ kaolinite, consistent with the increasing basicity of the halide anions and basic Brønsted sites on kaolinite. The dark heterogeneous reaction of NO2 with NaCl-adsorbed catechol at relative humidity (RH) <2% promoted nitration forming 4-nitrocatechol and oxidation forming 1,2-benzoquinone and the ring cleavage product muconic acid, with product yields of 88%, 8%, and 4%, respectively. 4-Nitrocatechol was the dominant product for catechol adsorbed on NaF and kaolinite, while NaBr-adsorbed catechol produced less 4-nitrocatechol and more 1,2-benzoquinone and muconic acid. For all three sodium halides, the reactions of NO2 with adsorbed catechol were orders of magnitude faster than between NO2 and each NaX substrate. 4-Nitrocatechol rates and product yields were consistent with the relative ability of each substrate to enhance the deprotonated nature of adsorbed-catechol. Increasing the relative humidity caused the rate of each product channel to decrease and also altered the product branching ratios. Most notably, 1,2-benzoquinone formation decreased significantly even at 13% RH. The dramatic

  18. EMERGING TECHNOLOGY SUMMARY: DEMONSTRATION OF AMBERSORB 563 ADSORBENT TECHNOLOGY

    EPA Science Inventory

    A field pilot study was conducted to demonstrate the technical feasibility and cost-effectiveness of Ambersorb® 5631 carbonaceous adsorbent for remediating groundwater contaminated with volatile organic compounds (VOCs). The Ambersorb adsorbent technology demonstration consist...

  19. A review of the use of red mud as adsorbent for the removal of toxic pollutants from water and wastewater.

    PubMed

    Bhatnagar, Amit; Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2011-01-01

    Red mud (an aluminium industry waste) has received wide attention as an effective adsorbent for water pollution control, showing significant adsorption potential for the removal of various aquatic pollutants. In this review, an extensive list of red-mud-based adsorbents has been compiled and their adsorption capacities (maximum uptake value of the adsorbent for the pollutant or adsorbate being removed) for various aquatic pollutants (metal ions, dyes, phenolic compounds, inorganic anions) are presented. The review provides a summary of recent information obtained using batch studies and deals with the adsorption mechanisms involved. It is evident from the literature survey that red mud has been found to be efficient for the removal of various aquatic pollutants, especially arsenic and phosphate. However, there is still a need to investigate the practical utility of these adsorbents on a commercial scale.

  20. Adsorption equilibrium and dynamics of gasoline vapors onto polymeric adsorbents.

    PubMed

    Jia, Lijuan; Yu, Weihua; Long, Chao; Li, Aimin

    2014-03-01

    The emission of gasoline vapors is becoming a significant environmental problem especially for the population-dense area and also results in a significant economic loss. In this study, adsorption equilibrium and dynamics of gasoline vapors onto macroporous and hypercrosslinked polymeric resins at 308 K were investigated and compared with commercial activated carbon (NucharWV-A 1100). The results showed that the equilibrium and breakthrough adsorption capacities of virgin macroporous and hypercrosslinked polymeric resins were lower than virgin-activated carbon. Compared with origin adsorbents, however, the breakthrough adsorption capacities of the regenerated activated carbon for gasoline vapors decreased by 58.5 % and 61.3 % when the initial concentration of gasoline vapors were 700 and 1,400 mg/L, while those of macroporous and hypercrosslinked resins decreased by 17.4 % and 17.5 %, and 46.5 % and 45.5 %, respectively. Due to the specific bimodal property in the region of micropore (0.5-2.0 nm) and meso-macropore (30-70 nm), the regenerated hypercrosslinked polymeric resin exhibited the comparable breakthrough adsorption capacities with the regenerated activated carbon at the initial concentration of 700 mg/L, and even higher when the initial concentration of gasoline vapors was 1,400 mg/L. In addition, 90 % of relative humidity had ignorable effect on the adsorption of gasoline vapors on hypercrosslinked polymeric resin. Taken together, it is expected that hypercrosslinked polymeric adsorbent would be a promising adsorbent for the removal of gasoline vapors from gas streams.

  1. Influence of adsorbents in transdermal matrix patches on the release and the physical state of ethinyl estradiol and levonorgestrel.

    PubMed

    Schulz, Martin; Fussnegger, Bernhard; Bodmeier, Roland

    2011-02-01

    The drug release from medium molecular weight polyisobutene patches containing adsorbates (drug content: 0.2% ethinyl estradiol, 1.0% levonorgestrel; adsorbent content: 20%, w/w) increased in the order of no adsorbentadsorbent and the water uptake which increased in the order of no adsorbent (0.1%)=titanium dioxide (0.1%)adsorbates onto crospovidone were investigated in detail. Increasing the adsorbate's drug loading increased the drug release up to a crospovidone content of 15% (w/w). Patches were crystal free for crospovidone contents ≥ 10% (w/w), which corresponds to a drug loading of crospovidone of 12% (w/w). In conclusion, the incorporation of drug adsorbates onto crospovidone into patches based on polyisobutene significantly increased the drug release (approximately 9.1 times for ethinyl estradiol and 15.4 times for levonorgestrel) and prevented drug recrystallization.

  2. Analytical supercritical fluid extraction of adsorbent materials

    SciTech Connect

    Wright, B.W.; Wright, C.W.; Gale, R.W.; Smith, R.D.

    1987-01-01

    The use of supercritical fluids for the analytical extraction of semivolatile and higher molecular weight materials from various adsorbent and particulate matrices was investigated. Instrumentation was designed to allow gram quantities of the matrix to be extracted at pressures up to 400 bar and temperatures to 235 /sup 0/C with collection of the effluent in a sealed liquid-nitrogen-cooled flask. Carbon dioxide, isobutane, and methanol modified (20 mol %) carbon dioxide fluid systems were evaluated and compared to liquid Soxhlet extraction. Supercritical fluid extraction (SFE) provided very rapid (approx. =30 min) extraction with comparable efficiency to the Soxhlet methods, and both more rapid and more efficient extractions appear feasible. The more polar carbon dioxide-methanol fluid system gave higher extraction efficiencies for the more polar adsorbates and the isobutane system was more efficient for the higher molecular weight and less polar compounds.

  3. Efficient adsorbate transport on graphene by electromigration

    NASA Astrophysics Data System (ADS)

    Velizhanin, Kirill; Solenov, Dmitry

    2012-02-01

    Chemical functionalization of the surface of graphene holds promise for various applications ranging from nanoelectronics to surface catalysis and nano-assembling. In many practical situations it would be beneficial to be able to propel adsorbates along the graphene sheet in a controlled manner. We propose to use electromigration as an efficient means to transport adsorbates along the graphene surface. Within the tight-binding approximation for graphene, parametrized by density functional theory calculations, we estimate the contributions of the direct force and the electron wind force to the drift velocity of electromigration and demonstrate that the electromigration can be rather efficient. In particular, we show that the drift velocity of atomic oxygen covalently bound to graphene can reach up to 4 cm/s for realistic graphene samples. Further, we discuss ways to dynamically, i.e., during experiment, control the efficiency of electromigration by charging and/or local heating of graphene.

  4. Sand consolidation methods using adsorbable catalysts

    SciTech Connect

    Friedman, R. H.

    1985-04-23

    Methods are provided for selectively consolidating sand grains within a subterranean formation. First an acidic zirconium salt catalyst, such as ZrOCl/sub 2/, Zr(SO/sub 4/)/sub 2/, or ZrCl/sub 4/, is injected into the subterranean formation, wherein the acidic salt catalyst is adsorbed to the surface of the sand grains. Next a polymerizable resin composition such as furfuryl alcohol oligomer is introduced into the well formation. Polymerization of the resin occurs upon exposure to the elevated well temperatures and contact with the acid salt catalyst adsorbed to the sand grains. The polymerized resin serves to consolidate the surfaces of the sand grains while retaining permeability through the pore spaces. An ester of a weak organic acid is included with the resin compositions to control the extent of a polymerization by consuming the water by-product formed during the polymerization reaction.

  5. Gas storage using fullerene based adsorbents

    NASA Technical Reports Server (NTRS)

    Loutfy, Raouf O. (Inventor); Lu, Xiao-Chun (Inventor); Li, Weijiong (Inventor); Mikhael, Michael G. (Inventor)

    2000-01-01

    This invention is directed to the synthesis of high bulk density high gas absorption capacity adsorbents for gas storage applications. Specifically, this invention is concerned with novel gas absorbents with high gravimetric and volumetric gas adsorption capacities which are made from fullerene-based materials. By pressing fullerene powder into pellet form using a conventional press, then polymerizing it by subjecting the fullerene to high temperature and high inert gas pressure, the resulting fullerene-based materials have high bulk densities and high gas adsorption capacities. By pre-chemical modification or post-polymerization activation processes, the gas adsorption capacities of the fullerene-based adsorbents can be further enhanced. These materials are suitable for low pressure gas storage applications, such as oxygen storage for home oxygen therapy uses or on-board vehicle natural gas storage. They are also suitable for storing gases and vapors such as hydrogen, nitrogen, carbon dioxide, and water vapor.

  6. Analysis of Adsorbed Natural Gas Tank Technology

    NASA Astrophysics Data System (ADS)

    Knight, Ernest; Schultz, Conrad; Rash, Tyler; Dohnke, Elmar; Stalla, David; Gillespie, Andrew; Sweany, Mark; Seydel, Florian; Pfeifer, Peter

    With gasoline being an ever decreasing finite resource and with the desire to reduce humanity's carbon footprint, there has been an increasing focus on innovation of alternative fuel sources. Natural gas burns cleaner, is more abundant, and conforms to modern engines. However, storing compressed natural gas (CNG) requires large, heavy gas cylinders, which limits space and fuel efficiency. Adsorbed natural gas (ANG) technology allows for much greater fuel storage capacity and the ability to store the gas at a much lower pressure. Thus, ANG tanks are much more flexible in terms of their size, shape, and weight. Our ANG tank employs monolithic nanoporous activated carbon as its adsorbent material. Several different configurations of this Flat Panel Tank Assembly (FPTA) along with a Fuel Extraction System (FES) were examined to compare with the mass flow rate demands of an engine.

  7. Aquaculture of Uranium in Seawater by a Fabric-Adsorbent Submerged System

    SciTech Connect

    Seko, Noriaki; Katakai, Akio; Hasegawa, Shin; Tamada, Masao; Kasai, Noboru; Takeda, Hayato; Sugo, Takanobu; Saito, Kyoichi

    2003-11-15

    The total amount of uranium dissolved in seawater at a uniform concentration of 3 mg U/m{sup 3} in the world's oceans is 4.5 billion tons. An adsorption method using polymeric adsorbents capable of specifically recovering uranium from seawater is reported to be economically feasible. A uranium-specific nonwoven fabric was used as the adsorbent packed in an adsorption cage 16 m{sup 2} in cross-sectional area and 16 cm in height. We submerged three adsorption cages in the Pacific Ocean at a depth of 20 m at 7 km offshore of Japan. The three adsorption cages consisted of stacks of 52 000 sheets of the uranium-specific non-woven fabric with a total mass of 350 kg. The total amount of uranium recovered by the nonwoven fabric was >1 kg in terms of yellow cake during a total submersion time of 240 days in the ocean.

  8. Local anesthetics adsorbed onto infusion balloon.

    PubMed

    Mizogami, Maki; Tsuchiya, Hironori; Takakura, Ko

    2004-09-01

    We compared the adsorption of different local anesthetics onto infusion balloons and studied one of the possible mechanisms for adsorption. After injection of lidocaine, bupivacaine, ropivacaine, and mepivacaine solutions (1 mM each; pH 7.4) into balloons of 100-mL volume, their concentrations in effluents flowing out at 4 mL/h were determined over time by high-performance liquid chromatography. All were adsorbed in a structure-dependent manner, and the concentration decreased by 6%-14% within 5 min. Bupivacaine was most strongly adsorbed, followed by lidocaine, ropivacaine, and mepivacaine. QX-314, a quaternary ammonium derivative of lidocaine, was only weakly adsorbed compared with the parent compound lidocaine. The extent of adsorption of local anesthetics was related to their hydrophobicity (evaluated by reversed-phase chromatography) and was much more at pH 7.4 than at pH 6.0. A hydrophobic interaction with balloon materials appears to be responsible for the adsorption of local anesthetics. When infusion balloons are used for the continuous administration of local anesthetics, attention should be paid to the possibility that their actual concentrations in effluents are smaller than those present when they are initially prepared.

  9. Physico-chemical properties of biodiesel manufactured from waste frying oil using domestic adsorbents.

    PubMed

    Ismail, Samir Abd-Elmonem A; Ali, Rehab Farouk M

    2015-06-01

    We have evaluated the efficiency of sugar cane bagasse ash (SCBA), date palm seed carbon (DPSC), and rice husk ash (RHA) as natural adsorbents and compared them with the synthetic adsorbent Magnesol XL for improving the quality of waste frying oil (WFO) and for the impact on the physicochemical properties of the obtained biodiesel. We measured moisture content, refractive index (RI), density, acid value (AV), iodine value (IV), peroxide value (PV), and saponification value (SV), as well as fatty acid profile. Purification treatments with various levels of adsorbents caused significant (P ≤ 0.05) decreases in free fatty acids (FFAs), PVs, and IVs. The highest yields (86.45 and 87.80%) were observed for biodiesel samples produced from WFO treated with 2% Magnesol and 3% of RHA, respectively, followed by samples treated with 2 and 3% of DPSC or RHA. Pre-treatments caused a significant decrease in the content of C 18:2 linoleic acids, consistent with a significant increase in the content of monounsaturated and saturated fatty acids (MUFA) in the treated samples. The highest oxidation value (COX) (1.30) was observed for biodiesel samples produced from WFO without purification treatments. However, the lowest values (0.44-0.73) were observed for biodiesel samples produced from WFO treated with different levels of adsorbents. Our results indicate that pre-treatments with different levels of adsorbents regenerated the quality of WFO and improved the quality of the obtained biodiesel.

  10. Physico-chemical properties of biodiesel manufactured from waste frying oil using domestic adsorbents

    NASA Astrophysics Data System (ADS)

    Ismail, Samir Abd-elmonem A.; Ali, Rehab Farouk M.

    2015-06-01

    We have evaluated the efficiency of sugar cane bagasse ash (SCBA), date palm seed carbon (DPSC), and rice husk ash (RHA) as natural adsorbents and compared them with the synthetic adsorbent Magnesol XL for improving the quality of waste frying oil (WFO) and for the impact on the physicochemical properties of the obtained biodiesel. We measured moisture content, refractive index (RI), density, acid value (AV), iodine value (IV), peroxide value (PV), and saponification value (SV), as well as fatty acid profile. Purification treatments with various levels of adsorbents caused significant (P ≤ 0.05) decreases in free fatty acids (FFAs), PVs, and IVs. The highest yields (86.45 and 87.80%) were observed for biodiesel samples produced from WFO treated with 2% Magnesol and 3% of RHA, respectively, followed by samples treated with 2 and 3% of DPSC or RHA. Pre-treatments caused a significant decrease in the content of C 18:2 linoleic acids, consistent with a significant increase in the content of monounsaturated and saturated fatty acids (MUFA) in the treated samples. The highest oxidation value (COX) (1.30) was observed for biodiesel samples produced from WFO without purification treatments. However, the lowest values (0.44-0.73) were observed for biodiesel samples produced from WFO treated with different levels of adsorbents. Our results indicate that pre-treatments with different levels of adsorbents regenerated the quality of WFO and improved the quality of the obtained biodiesel.

  11. Physico-chemical properties of biodiesel manufactured from waste frying oil using domestic adsorbents

    PubMed Central

    Ismail, Samir Abd-elmonem A; Ali, Rehab Farouk M

    2015-01-01

    We have evaluated the efficiency of sugar cane bagasse ash (SCBA), date palm seed carbon (DPSC), and rice husk ash (RHA) as natural adsorbents and compared them with the synthetic adsorbent Magnesol XL for improving the quality of waste frying oil (WFO) and for the impact on the physicochemical properties of the obtained biodiesel. We measured moisture content, refractive index (RI), density, acid value (AV), iodine value (IV), peroxide value (PV), and saponification value (SV), as well as fatty acid profile. Purification treatments with various levels of adsorbents caused significant (P ≤ 0.05) decreases in free fatty acids (FFAs), PVs, and IVs. The highest yields (86.45 and 87.80%) were observed for biodiesel samples produced from WFO treated with 2% Magnesol and 3% of RHA, respectively, followed by samples treated with 2 and 3% of DPSC or RHA. Pre-treatments caused a significant decrease in the content of C 18:2 linoleic acids, consistent with a significant increase in the content of monounsaturated and saturated fatty acids (MUFA) in the treated samples. The highest oxidation value (COX) (1.30) was observed for biodiesel samples produced from WFO without purification treatments. However, the lowest values (0.44–0.73) were observed for biodiesel samples produced from WFO treated with different levels of adsorbents. Our results indicate that pre-treatments with different levels of adsorbents regenerated the quality of WFO and improved the quality of the obtained biodiesel. PMID:27877789

  12. Affinity binding of antibodies to supermacroporous cryogel adsorbents with immobilized protein A for removal of anthrax toxin protective antigen.

    PubMed

    Ingavle, Ganesh C; Baillie, Les W J; Zheng, Yishan; Lis, Elzbieta K; Savina, Irina N; Howell, Carol A; Mikhalovsky, Sergey V; Sandeman, Susan R

    2015-05-01

    Polymeric cryogels are efficient carriers for the immobilization of biomolecules because of their unique macroporous structure, permeability, mechanical stability and different surface chemical functionalities. The aim of the study was to demonstrate the potential use of macroporous monolithic cryogels for biotoxin removal using anthrax toxin protective antigen (PA), the central cell-binding component of the anthrax exotoxins, and covalent immobilization of monoclonal antibodies. The affinity ligand (protein A) was chemically coupled to the reactive hydroxyl and epoxy-derivatized monolithic cryogels and the binding efficiencies of protein A, monoclonal antibodies to the cryogel column were determined. Our results show differences in the binding capacity of protein A as well as monoclonal antibodies to the cryogel adsorbents caused by ligand concentrations, physical properties and morphology of surface matrices. The cytotoxicity potential of the cryogels was determined by an in vitro viability assay using V79 lung fibroblast as a model cell and the results reveal that the cryogels are non-cytotoxic. Finally, the adsorptive capacities of PA from phosphate buffered saline (PBS) were evaluated towards a non-glycosylated, plant-derived human monoclonal antibody (PANG) and a glycosylated human monoclonal antibody (Valortim(®)), both of which were covalently attached via protein A immobilization. Optimal binding capacities of 108 and 117 mg/g of antibody to the adsorbent were observed for PANG attached poly(acrylamide-allyl glycidyl ether) [poly(AAm-AGE)] and Valortim(®) attached poly(AAm-AGE) cryogels, respectively, This indicated that glycosylation status of Valortim(®) antibody could significantly increase (8%) its binding capacity relative to the PANG antibody on poly(AAm-AGE)-protien-A column (p < 0.05). The amounts of PA which remained in the solution after passing PA spiked PBS through PANG or Valortim bound poly(AAm-AGE) cryogel were significantly (p < 0

  13. Mobilization of arsenite by dissimilatory reduction of adsorbed arsenate

    USGS Publications Warehouse

    Zobrist, J.; Dowdle, P.R.; Davis, J.A.; Oremland, R.S.

    2000-01-01

    Sulfurospirillum barnesii is capable of anaerobic growth using ferric iron or arsenate as electron acceptors. Cell suspensions of S. barnesii were able to reduce arsenate to arsenite when the former oxyanion was dissolved in solution, or when it was adsorbed onto the surface of ferrihydrite, a common soil mineral, by a variety of mechanisms (e.g., coprecipitation, presorption). Reduction of Fe(III) in ferrihydrite to soluble Fe(II) also occurred, but dissolution of ferrihydrite was not required in order for adsorbed arsenate reduction to be achieved. This was illustrated by bacterial reduction of arsenate coprecipitated with aluminum hydroxide, a mineral that does not undergo reductive dissolution. The rate of arsenate reduction was influenced by the method in which arsenate became associated with the mineral phases and may have been strongly coupled with arsenate desorption rates. The extent of release of arsenite into solution was governed by adsorption of arsenite onto the ferrihydrite or alumina phases. The results of these experiments have interpretive significance to the mobilization of arsenic in large alluvial aquifers, such as those of the Ganges in India and Bangladesh, and in the hyporheic zones of contaminated streams.Sulfurospirillum barnesii is capable of anaerobic growth using ferric iron or arsenate as electron acceptors. Cell suspensions of S. barnesii were able to reduce arsenate to arsenite when the former oxyanion was dissolved in solution, or when it was adsorbed onto the surface of ferrihydrite a common soil mineral, by a variety of mechanisms (e.g., coprecipitation, presorption). Reduction of Fe(III) in ferrihydrite to soluble Fe(II) also occurred, but dissolution of ferrihydrite was not required in order for adsorbed arsenate reduction to be achieved. This was illustrated by bacterial reduction of arsenate coprecipitated with aluminum hydroxide, a mineral that does not undergo reductive dissolution. The rate of arsenate reduction was

  14. Bromocriptine tablet of self-microemulsifying system adsorbed onto porous carrier to stimulate lipoproteins secretion for brain cellular uptake.

    PubMed

    Thongrangsalit, Sirigul; Phaechamud, Thawatchai; Lipipun, Vimolmas; Ritthidej, Garnpimol C

    2015-07-01

    Both low solubility and high hepatic metabolism cause low oral bioavailability of bromocriptine mesylate (BM) leading to very low drug amount in brain. Self-microemulsion (SME) tablets were developed to improve solubility, stimulate lipoprotein synthesis to promote lymphatic transport, avoid hepatic metabolism and target drug to brain. SME liquid containing castor oil, Tween(®) 80 and Cremophor(®) EL was prepared and then adsorbed onto solid carries, Aerosil(®)200, Aeroperl(®)300 or NeusilinUS2(®), yielding SME powders. The optimal ratios of SME liquid to carriers determined from flowability and scanning electron photomicrographs before tableting were 1.5:1, 2:1 and 2.5:1 for Aerosil(®)200, Aeroperl(®)300 and NeusilinUS2(®), respectively. Only Aeroperl(®)300 SME tablet had comparable dissolution to BM commercial tablet. From in vitro study in Caco-2 cells, fluorescein loaded SME tablet showed higher uptake than fluorescein loaded in either oil or surfactant. Although significantly lower amount of drug was permeated from SME tablet than from commercial tablet, higher drug uptake was obviously observed (P<0.05). In addition, higher lipoprotein synthesis expressing as content of apolipoprotein B (apo-B) found in secreted chylomicron resulted in higher drug uptake in co-culture of brain endothelial cells (bEnd.3) and astrocytes (CTX TNA2) from drug loaded SME tablet when compared to commercial tablet (P<0.05) due to binding of apo-B to LDL receptors expressed on the surface of endothelial cells. Therefore, tablet of SME adsorbed onto porous carrier potentially delivered BM to brain via lymphatic transport by increasing the lipoprotein synthesis.

  15. 46 CFR Sec. 2 - Amount of bond.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 8 2011-10-01 2011-10-01 false Amount of bond. Sec. 2 Section 2 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION A-NATIONAL SHIPPING AUTHORITY BONDING OF SHIP'S PERSONNEL Sec. 2 Amount of bond. The amount of the bond must be governed by the amount of monies advanced or value of...

  16. 46 CFR Sec. 2 - Amount of bond.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Amount of bond. Sec. 2 Section 2 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION A-NATIONAL SHIPPING AUTHORITY BONDING OF SHIP'S PERSONNEL Sec. 2 Amount of bond. The amount of the bond must be governed by the amount of monies advanced or value of...

  17. Type of adsorbent and column height in adsorption process of used cooking oil

    NASA Astrophysics Data System (ADS)

    Hasnelly, Hervelly, Taufik, Yusman; Melany, Ivo Nila

    2015-12-01

    The purpose of this research was to find out the best adsorbent and column height that can adsorb color and soluble impurities substances in used cooking oil. This research was meant for knowledge development of refined cooking oil technology. The used of this research was giving out information on the recycling process of used cooking oil. Research design used 2 × 2 factorial pattern in randomized group design with 6 repetitions. The first factor is adsorbent type (J) that consist of activated carbon (J1) and Zeolit (J2). The second factor is column height (K) with variations of 15 cm (k1) and 20 cm (k2). Chemical analysis parameter are free fatty acid, water content and saponification value. Physical parameter measurement was done on color with Hunter Lab system analysis and viscosity using viscometer method. Chemical analysis result of preliminary research on used cooking oil showed water content of 1,9%, free fatty acid 1,58%, saponification value 130,79 mg KOH/g oil, viscosity 0,6 d Pas and color with L value of -27,60, a value 1,04 and b value 1,54. Result on main research showed that adsorbent type only gave effect on water content whereas column height and its interaction was not gave significant effect on water content. Interaction between adsorbent type (J) and column height (K) gave significant effect to free fatty acid, saponification value, viscosity and color for L, a and b value of recycled cooking oil.

  18. Negatively charged ions on Mg(0001) surfaces: appearance and origin of attractive adsorbate-adsorbate interactions.

    PubMed

    Cheng, Su-Ting; Todorova, Mira; Freysoldt, Christoph; Neugebauer, Jörg

    2014-09-26

    Adsorption of electronegative elements on a metal surface usually leads to an increase in the work function and decrease in the binding energy as the adsorbate coverage rises. Using density-functional theory calculations, we show that Cl adsorbed on a Mg(0001) surface complies with these expectations, but adsorption of {N,O,F} causes a decrease in the work function and an increase in the binding energy. Analyzing the electronic structure, we show that the presence of a highly polarizable electron spill-out in front of Mg(0001) causes this unusual adsorption behavior and is responsible for the appearance of a hitherto unknown net-attractive lateral electrostatic interaction between same charged adsorbates.

  19. The Uranium from Seawater Program at the Pacific Northwest National Laboratory: Overview of Marine Testing, Adsorbent Characterization, Adsorbent Durability, Adsorbent Toxicity, and Deployment Studies

    SciTech Connect

    Gill, Gary A.; Kuo, Li-Jung; Janke, Chris J.; Park, Jiyeon; Jeters, Robert T.; Bonheyo, George T.; Pan, Horng-Bin; Wai, Chien; Khangaonkar, Tarang; Bianucci, Laura; Wood, Jordana R.; Warner, Marvin G.; Peterson, Sonja; Abrecht, David G.; Mayes, Richard T.; Tsouris, Costas; Oyola, Yatsandra; Strivens, Jonathan E.; Schlafer, Nicholas J.; Addleman, R. Shane; Chouyyok, Wilaiwan; Das, Sadananda; Kim, Jungseung; Buesseler, Ken; Breier, Crystal; D’Alessandro, Evan

    2016-02-07

    The Pacific Northwest National Laboratory’s (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacity and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 ± 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 ± 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage

  20. Evaluation of pharmaceuticals removal by sewage sludge-derived adsorbents with rapid small-scale column tests

    NASA Astrophysics Data System (ADS)

    Zhang, P.; Ding, R.; Wallace, R.; Bandosz, T.

    2015-12-01

    New composite adsorbents were developed by pyrolyzing sewage sludge and fish waste (75:25 or 90:10 dry mass ratio) at 650 oC and 950 oC. Batch adsorption experiments demonstrated that the composite adsorbents were able to adsorb a wide range of organic contaminants (volatile organic compounds, pharmaceuticals and endocrine disrupting compounds (EDCs), and nitrosamine disinfection byproducts) with high capacities. Here we further examine the performance of the adsorbents for the simultaneous removal of 8 pharmaceuticals and EDCs with rapid small-scale column tests (RSSCT). Results show that the order of breakthrough in RSSCT is in general consistent with the affinity determined via batch tests. As expected, the maximum amount of adsorption for each compound obtained from RSSCT is identical to or less than that obtained from batch tests (with only one exception), due to adsorption kinetics. However, despite the very different input concentration (1 mg/L vs. 100 mg/L) and contact time (2 min empty bed contact time vs. 16 hour equilibrium time) used in RSSCT and batch tests, the maximum amount of pharmaceuticals and EDCs adsorbed under RSSCT is still about one half of that under equilibrium batch tests, validating the approach of using batch tests with much higher input concentrations to determine adsorption capacities. Results of a pilot-scale column test in a drinking water treatment plant for pharmaceuticals removal will also be presented.

  1. A potential low cost adsorbent for the removal of cationic dyes from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Uddin, Md. Tamez; Rahman, Md. Arifur; Rukanuzzaman, Md.; Islam, Md. Akhtarul

    2017-03-01

    This study was aimed at using mango leaf powder (MLP) as a potential adsorbent for the removal of methylene blue (MB) from aqueous solutions. Characterization of the adsorbent was carried out with scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption analysis. The pH at the point of zero charge of the adsorbent was determined by titration method and was found a value to be 5.6 ± 0.2. Batch studies were performed to evaluate the influence of various experimental parameters like initial solution pH, contact time, initial concentration of dye and adsorbent dosage on the removal of MB. An adsorption-desorption study was carried out resulting the mechanism of adsorption was carried out by electrostatic force of attraction. The adsorption equilibrium time required for the adsorption of MB on MLP was almost 2 h and 85 ± 5% of the total amount of dye uptake was found to occur in the first rapid phase (30 min). The Langmuir and Freundlich isotherm models were used for modeling the adsorption equilibrium. The experimental equilibrium data could be well interpreted by Langmuir isotherm with maximum adsorption capacity of 156 mg/g. To state the sorption kinetics, the fits of pseudo-first-order and pseudo-second-order kinetic models were investigated. It was obtained that the adsorption process followed the pseudo-second-order rate kinetics. The above findings suggest that MLP can be effectively used for decontamination of dye containing wastewater.

  2. Adsorbent capability testing using desorption efficiency method on palm oil fiber

    NASA Astrophysics Data System (ADS)

    Manap, Nor Rahafza Abdul; Shamsudin, Roslinda

    2015-09-01

    The palm oil fiber had been used as filler in making thermoplastics, biocomposites and also used as adsorbent in treating waste water. In this study, palm oil fiber was used as adsorbent to treat indoor air pollutants that caused by toluene, ethylbenzene, ortho-, meta-, and para- xylene (o-, m-, p-xylene). Known amount of pollutants, ranges between 1.3 to 28 ppm was spiked into palm oil fiber and left in refrigerator for 24 hours. Then, elution of the pollutants was carried out by carbon disulphide as mobile phase or eluent. The ability of palm oil fiber as adsorbent was determine using desorption efficiency technique by gas chromatography with flame ionization detector (GC/FID). The desorption efficiency percentage given by toluene was in the range of 88.9% to 100%, 91% to 100% for ethylbenzene, 65% to 100% for pm-xylene and 92.9% to 100% for o-xylene. This percentage indicates that palm oil fiber can be used as adsorbent to treat indoor air pollutants.

  3. The molecular mechanism of mediation of adsorbed serum proteins to endothelial cells adhesion and growth on biomaterials.

    PubMed

    Yang, Dayun; Lü, Xiaoying; Hong, Ying; Xi, Tingfei; Zhang, Deyuan

    2013-07-01

    To explore molecular mechanism of mediation of adsorbed proteins to cell adhesion and growth on biomaterials, this study examined endothelial cell adhesion, morphology and viability on bare and titanium nitride (TiN) coated nickel titanium (NiTi) alloys and chitosan film firstly, and then identified the type and amount of serum proteins adsorbed on the three surfaces by proteomic technology. Subsequently, the mediation role of the identified proteins to cell adhesion and growth was investigated with bioinformatics analyses, and further confirmed by a series of cellular and molecular biological experiments. Results showed that the type and amount of adsorbed serum proteins associated with cell adhesion and growth was obviously higher on the alloys than on the chitosan film, and these proteins mediated endothelial cell adhesion and growth on the alloys via four ways. First, proteins such as adiponectin in the adsorbed protein layer bound with cell surface receptors to generate signal transduction, which activated cell surface integrins through increasing intracellular calcium level. Another way, thrombospondin 1 in the adsorbed protein layer promoted TGF-β signaling pathway activation and enhanced integrins expression. The third, RGD sequence containing proteins such as fibronectin 1, vitronectin and thrombospondin 1 in the adsorbed protein layer bound with activated integrins to activate focal adhesion pathway, increased focal adhesion formation and actin cytoskeleton organization and mediated cell adhesion and spreading. In addition, the activated focal adhesion pathway promoted the expression of cell growth related genes and resulted in cell proliferation. The fourth route, coagulation factor II (F2) and fibronectin 1 in the adsorbed protein layer bound with cell surface F2 receptor and integrin, activated regulation of actin cytoskeleton pathway and regulated actin cytoskeleton organization.

  4. Sustainable conversion of agro-wastes into useful adsorbents

    NASA Astrophysics Data System (ADS)

    Bello, Olugbenga Solomon; Owojuyigbe, Emmanuel Seun; Babatunde, Monsurat Abiodun; Folaranmi, Folasayo Eunice

    2016-11-01

    Preparation and characterization of raw and activated carbon derived from three different selected agricultural wastes: kola nut pod raw and activated (KNPR and KNPA), bean husk raw and activated (BHR and BHA) and coconut husk raw and activated (CHR and CHA) were investigated, respectively. Influences of carbonization and acid activation on the activated carbon were investigated using SEM, FTIR, EDX, pHpzc and Boehm titration techniques, respectively. Carbonization was done at 350 °C for 2 h followed by activation with 0.3 M H3PO4 (ortho-phosphoric acid). Results obtained from SEM, FTIR, and EDX revealed that, carbonization followed by acid activation had a significant influence on morphology and elemental composition of the samples. SEM showed well-developed pores on the surface of the precursors after acid treatment, FTIR spectra revealed reduction, broadening, disappearance or appearance of new peaks after acid activation. EDX results showed highest percentage of carbon by atom respectively in the order BHA > KNPA > CHA respectively. The pHpzc was found to be 5.32, 4.57 and 3.69 for KNPA, BHA and CHA, respectively. Boehm titration result compliments that of pHpzc, indicating that the surfaces of the prepared adsorbents are predominantly acidic. This study promotes a sustainable innovative use of agro-wastes in the production of cheap and readily available activated carbons, thereby ensuring more affordable water and effluent treatment adsorbents.

  5. Fibrous adsorbent for removal of aqueous aromatic hydrocarbons.

    PubMed

    Jung, Yong-Jun; Kiso, Yoshiaki; Oguchi, Tatsuo; Yamada, Toshiro; Takagi, Hiroo; Nishimura, Kazuyuki

    2007-01-01

    Bundles of a strongly hydrophobic fibrous material (p-phenylene-2,6-benzobisoxazole; PBO; Zylon) were employed as an adsorbent for the removal of aqueous aromatic compounds, because the PBO fibers are too rigid to be woven and did not entrap suspended solids. The removal performance for nine kinds of polyaromatic hydrocarbons (PAHs) and di-(2-ethylhexyl) phthalate (DEHP) was evaluated. PAHs and DEHP at initial concentrations of 50 microg L(-1) were removed at 72.5-99.9% and ca. 95%, respectively, although the removal efficiencies were affected by the phase ratio (fiber weight/solution volume). The logarithm of the partition coefficient (log K) for planar PAHs was linearly correlated with the logarithm of the n-octanol/water partition coefficient (log P), but nonplanar PAHs, such as cis-stilbene, p-terphenyl, and o-terphenyl, showed significantly lower adsorption performance. The adsorbed PAHs were not desorbed effectively with CH3CN, CH2Cl2, and toluene. On the other hand, DEHP was effectively desorbed with methanol.

  6. Recovery of Technetium Adsorbed on Charcoal

    SciTech Connect

    Engelmann, Mark D.; Metz, Lori A.; Ballou, Nathan E.

    2006-05-01

    Two methods capable of near complete recovery of technetium adsorbed on charcoal are presented. The first involves liquid extraction of the technetium from the charcoal by hot 4M nitric acid. An average recovery of 98% (n=3) is obtained after three rounds of extraction. The second method involves dry ashing with air in a quartz combustion tube at 400-450 C. This method yields an average recovery of 96% (n=5). Other thermal methods were attempted, but resulted in reduced recovery and incomplete material balance

  7. Removal performance of elemental mercury by low-cost adsorbents prepared through facile methods of carbonisation and activation of coconut husk.

    PubMed

    Johari, Khairiraihanna; Alias, Afidatul Shazwani; Saman, Norasikin; Song, Shiow Tien; Mat, Hanapi

    2015-01-01

    The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g(-1)), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature.

  8. 29 CFR 4219.13 - Amount of liability for de minimis amounts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false Amount of liability for de minimis amounts. 4219.13 Section... Redetermination of Withdrawal Liability Upon Mass Withdrawal § 4219.13 Amount of liability for de minimis amounts. An employer that is liable for de minimis amounts shall be liable to the plan for the amount by...

  9. 29 CFR 4219.13 - Amount of liability for de minimis amounts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 9 2011-07-01 2011-07-01 false Amount of liability for de minimis amounts. 4219.13 Section... Redetermination of Withdrawal Liability Upon Mass Withdrawal § 4219.13 Amount of liability for de minimis amounts. An employer that is liable for de minimis amounts shall be liable to the plan for the amount by...

  10. 29 CFR 4219.13 - Amount of liability for de minimis amounts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 9 2012-07-01 2012-07-01 false Amount of liability for de minimis amounts. 4219.13 Section... Redetermination of Withdrawal Liability Upon Mass Withdrawal § 4219.13 Amount of liability for de minimis amounts. An employer that is liable for de minimis amounts shall be liable to the plan for the amount by...

  11. 29 CFR 4219.13 - Amount of liability for de minimis amounts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 9 2014-07-01 2014-07-01 false Amount of liability for de minimis amounts. 4219.13 Section... Redetermination of Withdrawal Liability Upon Mass Withdrawal § 4219.13 Amount of liability for de minimis amounts. An employer that is liable for de minimis amounts shall be liable to the plan for the amount by...

  12. 29 CFR 4219.13 - Amount of liability for de minimis amounts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 9 2013-07-01 2013-07-01 false Amount of liability for de minimis amounts. 4219.13 Section... Redetermination of Withdrawal Liability Upon Mass Withdrawal § 4219.13 Amount of liability for de minimis amounts. An employer that is liable for de minimis amounts shall be liable to the plan for the amount by...

  13. Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2016-09-06

    A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  14. Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J; Dai, Sheng; Oyola, Yatsandra

    2014-05-13

    A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  15. Epoxide-functionalization of polyethyleneimine for synthesis of stable carbon dioxide adsorbent in temperature swing adsorption

    PubMed Central

    Choi, Woosung; Min, Kyungmin; Kim, Chaehoon; Ko, Young Soo; Jeon, Jae Wan; Seo, Hwimin; Park, Yong-Ki; Choi, Minkee

    2016-01-01

    Amine-containing adsorbents have been extensively investigated for post-combustion carbon dioxide capture due to their ability to chemisorb low-concentration carbon dioxide from a wet flue gas. However, earlier studies have focused primarily on the carbon dioxide uptake of adsorbents, and have not demonstrated effective adsorbent regeneration and long-term stability under such conditions. Here, we report the versatile and scalable synthesis of a functionalized-polyethyleneimine (PEI)/silica adsorbent which simultaneously exhibits a large working capacity (2.2 mmol g−1) and long-term stability in a practical temperature swing adsorption process (regeneration under 100% carbon dioxide at 120 °C), enabling the separation of concentrated carbon dioxide. We demonstrate that the functionalization of PEI with 1,2-epoxybutane reduces the heat of adsorption and facilitates carbon dioxide desorption (>99%) during regeneration compared with unmodified PEI (76%). Moreover, the functionalization significantly improves long-term adsorbent stability over repeated temperature swing adsorption cycles due to the suppression of urea formation and oxidative amine degradation. PMID:27572662

  16. Epoxide-functionalization of polyethyleneimine for synthesis of stable carbon dioxide adsorbent in temperature swing adsorption.

    PubMed

    Choi, Woosung; Min, Kyungmin; Kim, Chaehoon; Ko, Young Soo; Jeon, Jae Wan; Seo, Hwimin; Park, Yong-Ki; Choi, Minkee

    2016-08-30

    Amine-containing adsorbents have been extensively investigated for post-combustion carbon dioxide capture due to their ability to chemisorb low-concentration carbon dioxide from a wet flue gas. However, earlier studies have focused primarily on the carbon dioxide uptake of adsorbents, and have not demonstrated effective adsorbent regeneration and long-term stability under such conditions. Here, we report the versatile and scalable synthesis of a functionalized-polyethyleneimine (PEI)/silica adsorbent which simultaneously exhibits a large working capacity (2.2 mmol g(-1)) and long-term stability in a practical temperature swing adsorption process (regeneration under 100% carbon dioxide at 120 °C), enabling the separation of concentrated carbon dioxide. We demonstrate that the functionalization of PEI with 1,2-epoxybutane reduces the heat of adsorption and facilitates carbon dioxide desorption (>99%) during regeneration compared with unmodified PEI (76%). Moreover, the functionalization significantly improves long-term adsorbent stability over repeated temperature swing adsorption cycles due to the suppression of urea formation and oxidative amine degradation.

  17. Adsorption of bisphenol-A from aqueous solution onto minerals and carbon adsorbents.

    PubMed

    Tsai, Wen-Tien; Lai, Chi-Wei; Su, Ting-Yi

    2006-06-30

    The adsorption behaviors of bisphenol-A, which has been listed as one of endocrine disrupting chemicals, from aqueous solution onto four minerals including andesite, diatomaceous earth, titanium dioxide, and activated bleaching earth, and two activated carbons with coconut-based and coal-based virgins were examined in this work. Based on the adsorption results at the specified conditions, the adsorption capacities of activated carbons are significantly larger than those of mineral adsorbents, implying that the former is effective for removal of the highly hydrophobic adsorbate from the aqueous solution because of its high surface area and low surface polarity. The adsorption capacities of bisphenol-A onto these mineral adsorbents with different pore properties are almost similar in magnitude mainly due to the weakly electrostatic interaction between the mineral surface with negative charge and the target adsorbate with hydrophobic nature. Further, a simplified kinetic model, pseudo-second-order, was tested to investigate the adsorption behaviors of bisphenol-A onto the two common activated carbons at different solution conditions. It was found that the adsorption process could be well described with the pseudo-second-order model. The kinetic parameters of the model obtained in the present work are in line with the pore properties of the two adsorbents.

  18. Epoxide-functionalization of polyethyleneimine for synthesis of stable carbon dioxide adsorbent in temperature swing adsorption

    NASA Astrophysics Data System (ADS)

    Choi, Woosung; Min, Kyungmin; Kim, Chaehoon; Ko, Young Soo; Jeon, Jae Wan; Seo, Hwimin; Park, Yong-Ki; Choi, Minkee

    2016-08-01

    Amine-containing adsorbents have been extensively investigated for post-combustion carbon dioxide capture due to their ability to chemisorb low-concentration carbon dioxide from a wet flue gas. However, earlier studies have focused primarily on the carbon dioxide uptake of adsorbents, and have not demonstrated effective adsorbent regeneration and long-term stability under such conditions. Here, we report the versatile and scalable synthesis of a functionalized-polyethyleneimine (PEI)/silica adsorbent which simultaneously exhibits a large working capacity (2.2 mmol g-1) and long-term stability in a practical temperature swing adsorption process (regeneration under 100% carbon dioxide at 120 °C), enabling the separation of concentrated carbon dioxide. We demonstrate that the functionalization of PEI with 1,2-epoxybutane reduces the heat of adsorption and facilitates carbon dioxide desorption (>99%) during regeneration compared with unmodified PEI (76%). Moreover, the functionalization significantly improves long-term adsorbent stability over repeated temperature swing adsorption cycles due to the suppression of urea formation and oxidative amine degradation.

  19. Removal of lead and zinc ions from water by low cost adsorbents.

    PubMed

    Mishra, P C; Patel, R K

    2009-08-30

    In this study, activated carbon, kaolin, bentonite, blast furnace slag and fly ash were used as adsorbent with a particle size between 100 mesh and 200 mesh to remove the lead and zinc ions from water. The concentration of the solutions prepared was in the range of 50-100 mg/L for lead and zinc for single and binary systems which are diluted as required for batch experiments. The effect of contact time, pH and adsorbent dosage on removal of lead and zinc by adsorption was investigated. The equilibrium time was found to be 30 min for activated carbon and 3h for kaolin, bentonite, blast furnace slag and fly ash. The most effective pH value for lead and zinc removal was 6 for activated carbon. pH value did not effect lead and zinc removal significantly for other adsorbents. Adsorbent doses were varied from 5 g/L to 20 g/L for both lead and zinc solutions. An increase in adsorbent doses increases the percent removal of lead and zinc. A series of isotherm studies was undertaken and the data evaluated for compliance was found to match with the Langmuir and Freundlich isotherm models. To investigate the adsorption mechanism, the kinetic models were tested, and it follows second order kinetics. Kinetic studies reveals that blast furnace slag was not effective for lead and zinc removal. The bentonite and fly ash were effective for lead and zinc removal.

  20. Improvement of cesium leaching resistance of solidified borate wastes with copper-ferrocyanide-vermiculite adsorbent

    SciTech Connect

    Huang, C.T.; Wu, G.

    1996-09-01

    Removal of cesium from deionized water, sea water, and lime water with copper ferrocyanide (CFC) and porous media including silica gel, bentonite, vermiculite, and zeolite were investigated; CFC and vermiculite were incorporated to prepare a compound adsorbent which was used to improve the Cs-leaching resistance of solidified borate wastes. It was shown that the Cs-removal efficiency by CFC is largely affected by pHs of the solutions, good cesium removal occurs in pHs ranged from 3 to 12 and the best from 7 to 10; the effect of Cs concentration is significantly only from lime water for Cs > 10{sup {minus}6} M at high pH and is insignificant from other solutions. Vermiculite and zeolite were shown to have better removal efficiency than silica gel and bentonite, and vermiculite was chosen to incorporate with CFC to make compound adsorbents because of its good compatibility with CFC. Compound adsorbents with different CFC contents were used as additives in the solidification of borate radwaste for improving the cesium leaching resistance of waste forms. Experimental results showed that the measured, cesium leaching index following ANSI/ANS 16.1, was increased from 7.96 to 9.76 by adding 0.25% of a compound adsorbent containing 20% CFC and 80% vermiculite, which indicated that the CFC-vermiculite compound adsorbent is very useful for improving cesium leaching resistance of the solidified borate radwastes.

  1. Adsorbed Fibrinogen Enhances Production of Bone- and Angiogenic-Related Factors by Monocytes/Macrophages

    PubMed Central

    Maciel, Joana; Oliveira, Marta I.; Colton, Erica; McNally, Amy K.; Oliveira, Carla; Anderson, James M.

    2014-01-01

    Macrophages are phagocytic cells with great importance in guiding multiple stages of inflammation and tissue repair. By producing a large number of biologically active molecules, they can affect the behavior of other cells and events, such as the foreign body response and angiogenesis. Since protein adsorption to biomaterials is crucial for the inflammatory process, we addressed the ability of the pro-inflammatory molecule fibrinogen (Fg) to modulate macrophage behavior toward tissue repair/regeneration. For this purpose, we used chitosan (Ch) as a substrate for Fg adsorption. Freshly isolated human monocytes were seeded on Ch substrates alone or previously adsorbed with Fg, and allowed to differentiate into macrophages for 10 days. Cell adhesion and morphology, formation of foreign body giant cells (FBGC), and secretion of a total of 80 cytokines and growth factors were evaluated. Both substrates showed similar numbers of adherent macrophages along differentiation as compared with RGD-coated surfaces, which were used as positive controls. Fg did not potentiate FBGC formation. In addition, actin cytoskeleton staining revealed the presence of punctuate F-actin with more elongated and interconnecting cells on Ch substrates. Antibody array screening and quantification of inflammation- and wound-healing-related factors indicated an overall reduction in Ch-based substrates versus RGD-coated surfaces. At late times, most inflammatory agents were down-regulated in the presence of Fg, in contrast to growth factor production, which was stimulated by Fg. Importantly, on Ch+Fg substrates, fully differentiated macrophages produced significant amounts of macrophage inflammatory protein-1delta (MIP-1δ), platelet-derived growth factor-BB, bone morphogenetic protein (BMP)-5, and BMP-7 compared with Ch alone. In addition, other important factors involved in bone homeostasis and wound healing, such as growth hormone, transforming growth factor-β3, and insulin-like growth factor

  2. Classical and Mixed Quantum-Classical Dynamics of Adsorbate-Surface Systems: Application to Non-Thermal Desorption

    NASA Astrophysics Data System (ADS)

    Dzegilenko, Fedor N.

    1995-01-01

    Both classical and mixed quantum-classical approaches have been used to study the non-thermal desorption of CO from a variety of model surfaces to which it is weakly adsorbed. In addition to three degrees of freedom for the CO adsorbate (bond stretching, physisorption, libration) which are treated quantum mechanically in the mixed method, a significant number of lattice degrees of freedom have been included using the generalized Langevin approximation. In the mixed method, two sets of equations for the quantum and classical subsystems (coupled via the Ehrenfest theorem) are solved self-consistently using the discrete variable representation method for the propagation of the quantum wave function. Non-thermal amounts of energy have been put into both the CO stretching and librational modes at t = 0. We find that for initial values of the stretching quantum number vstr = 0 -4 desorption does not take place at all within the simulation time unless there is also significant librational excitation. The detailed mechanism by which librational energy causes desorption is discussed. The role of the surface is also explored; we find that the probability of desorption is a non-monotonic function of the Debye frequency of the solid in the range 28-5000 cm^{-1}, and is larger for "non-rigid" lattices with low Debye frequencies in both of the methods. The classical results are explained in terms of resonances between low frequency libration and physisorption modes and high frequency phonon modes. For the combined method, two different mechanisms for desorption (due to lattice effects and due to symmetry properties of wave function) have been found and analyzed in detail. A comparative analysis of the two methods is presented and the limitations of the mixed scheme are discussed. An indirect mechanism for populating rapidly desorbing, highly excited levels of surface CO, based on intermolecular V to V,R energy exchange between the CO and vibrationally excited surface hydroxyl

  3. Validation of adsorbents for sample preconcentration in compound-specific isotope analysis of common vapor intrusion pollutants.

    PubMed

    Klisch, Monika; Kuder, Tomasz; Philp, R Paul; McHugh, Thomas E

    2012-12-28

    Isotope ratios of volatile organic compounds (VOCs) in the environment are often of interest in contaminant fate studies. Adsorbent preconcentration-thermal desorption of VOCs can be used to collect environmental vapor samples for compound-specific isotope analysis (CSIA). While active adsorbent samplers offer logistic benefits in handling large volumes of air, their performance in preserving VOCs isotope ratios was not previously tested under sampling conditions corresponding to typical indoor air sampling conditions. In this study, the performance of selected adsorbents was tested for preconcentration of TCE (for determination of C and Cl isotope ratios), PCE (C and Cl) and benzene (C and H). The key objective of the study was to identify the adsorbent(s) permitting preconcentration of the target VOCs present in air at low μg/m(3) concentrations, without significant alteration of their isotope ratios. Carboxen 1016 was found to perform well for the full range of tested parameters. Carboxen 1016 can be recommended for sampling of TCE, PCE and benzene, for CSIA, from air volumes up to 100 L. Variable extent of isotope ratio alteration was observed in the preconcentration of the target VOCs on Carbopack B and Carbopack X, resulting from partial analyte loss via adsorbent bed breakthrough and (possibly) via incomplete desorption. The results from testing the Carbopack B and Carbopack X highlight the need of adsorbent performance validation at conditions fully representative of actual sample collection conditions, and caution against extrapolation of performance data toward more challenging sampling conditions.

  4. A reexamination of the effects of adsorbates on the Raman spectrum of gibbsite.

    USGS Publications Warehouse

    Cunningham, K.W.; Goldberg, M.C.

    1983-01-01

    Previous workers have attributed substantial changes in the Raman intensities of the OH stretching bands in solid, powdered gibbsite of surface area 10 m2/g to surface interactions with the adsorbates 093Ca2+,HxPO43x- and SiO2.xH2O. These changes apparently resulted from an unsatisfactory Raman measurement procedure as a re-examination using an internal intensity standard (Na2C2O4 crystals) with gibbsite of surface area 39 m2/g showed no significant changes in the low-frequency band-height ratios of gibbsite and adsorbates.-D.J.M.

  5. Treatment of malachite green-containing wastewater using poultry feathers as adsorbent.

    PubMed

    Beak, Mi H; Ijagbemi, Christianah O; Kim, Dong S

    2009-04-01

    The feasibility of using feathers, a waste from poultry as an absorbent for malachite green in dye wastewater was studied. The batch adsorption tests were shown to be influenced by the concentration of the dye, reaction temperature, solution pH, and pre-treatment with ethanol. In order to establish the equilibrium state of the process, a kinetic study was conducted for an optimal practice of adsorption treatment process. The adsorption reached equilibrium within 120 min in the range of dye concentration studied. It was found that the adsorption rate increases especially at low concentrations of dye and the adsorption data fitted well to the first-order reaction kinetics over all dye concentration range. Absolute amount of adsorbed malachite green at equilibrium condition decreased as concentration decreases. Adsorption of malachite green on poultry feathers fitted well to the Langmuir isotherm model. As temperature increases, the adsorbed amount of malachite green at equilibrium also increased, indicating an endothermic adsorption reaction. In addition, the color removal of malachite green rapidly increased with increase in dye's water pH. The pre-treatment of adsorbent with ethanol produced initial slow rate of malachite green removal but after about 100 min of reaction time, same removal rate was observed compare with the untreated feathers.

  6. Adsorbate-driven morphological changes on Cu(111) nano-pits

    DOE PAGES

    Mudiyanselage, K.; Xu, F.; Hoffmann, F. M.; ...

    2014-12-09

    Adsorbate-driven morphological changes of pitted-Cu(111) surfaces have been investigated following the adsorption and desorption of CO and H. The morphology of the pitted-Cu(111) surfaces, prepared by Ar+ sputtering, exposed a few atomic layers deep nested hexagonal pits of diameters from 8 to 38 nm with steep step bundles. The roughness of pitted-Cu(111) surfaces can be healed by heating to 450-500 K in vacuum. Adsorption of CO on the pitted-Cu(111) surface leads to two infrared peaks at 2089-2090 and 2101-2105 cm-1 for CO adsorbed on under-coordinated sites in addition to the peak at 2071 cm-1 for CO adsorbed on atop sitesmore » of the close-packed Cu(111) surface. CO adsorbed on under-coordinated sites is thermally more stable than that of atop Cu(111) sites. Annealing of the CO-covered surface from 100 to 300 K leads to minor changes of the surface morphology. In contrast, annealing of a H covered surface to 300 K creates a smooth Cu(111) surface as deduced from infrared data of adsorbed CO and scanning tunnelling microscopy (STM) imaging. The observation of significant adsorbate-driven morphological changes with H is attributed to its stronger modification of the Cu(111) surface by the formation of a sub-surface hydride with a hexagonal structure, which relaxes into the healed Cu(111) surface upon hydrogen desorption. These morphological changes occur ~150 K below the temperature required for healing of the pitted-Cu(111) surface by annealing in vacuum. In contrast, the adsorption of CO, which only interacts with the top-most Cu layer and desorbs by 160 K, does not significantly change the morphology of the pitted-Cu(111) surface.« less

  7. Adsorbate-driven morphological changes on Cu(111) nano-pits

    SciTech Connect

    Mudiyanselage, K.; Xu, F.; Hoffmann, F. M.; Hrbek, J.; Waluyo, I.; Boscoboinik, J. A.; Stacchiola, D. J.

    2014-12-09

    Adsorbate-driven morphological changes of pitted-Cu(111) surfaces have been investigated following the adsorption and desorption of CO and H. The morphology of the pitted-Cu(111) surfaces, prepared by Ar+ sputtering, exposed a few atomic layers deep nested hexagonal pits of diameters from 8 to 38 nm with steep step bundles. The roughness of pitted-Cu(111) surfaces can be healed by heating to 450-500 K in vacuum. Adsorption of CO on the pitted-Cu(111) surface leads to two infrared peaks at 2089-2090 and 2101-2105 cm-1 for CO adsorbed on under-coordinated sites in addition to the peak at 2071 cm-1 for CO adsorbed on atop sites of the close-packed Cu(111) surface. CO adsorbed on under-coordinated sites is thermally more stable than that of atop Cu(111) sites. Annealing of the CO-covered surface from 100 to 300 K leads to minor changes of the surface morphology. In contrast, annealing of a H covered surface to 300 K creates a smooth Cu(111) surface as deduced from infrared data of adsorbed CO and scanning tunnelling microscopy (STM) imaging. The observation of significant adsorbate-driven morphological changes with H is attributed to its stronger modification of the Cu(111) surface by the formation of a sub-surface hydride with a hexagonal structure, which relaxes into the healed Cu(111) surface upon hydrogen desorption. These morphological changes occur ~150 K below the temperature required for healing of the pitted-Cu(111) surface by annealing in vacuum. In contrast, the adsorption of CO, which only interacts with the top-most Cu layer and desorbs by 160 K, does not significantly change the morphology of the pitted-Cu(111) surface.

  8. The amount effect and marginal value.

    PubMed

    Rachlin, Howard; Arfer, Kodi B; Safin, Vasiliy; Yen, Ming

    2015-07-01

    The amount effect of delay discounting (by which the value of larger reward amounts is discounted by delay at a lower rate than that of smaller amounts) strictly implies that value functions (value as a function of amount) are steeper at greater delays than they are at lesser delays. That is, the amount effect and the difference in value functions at different delays are actually a single empirical finding. Amount effects of delay discounting are typically found with choice experiments. Value functions for immediate rewards have been empirically obtained by direct judgment. (Value functions for delayed rewards have not been previously obtained.) The present experiment obtained value functions for both immediate and delayed rewards by direct judgment and found them to be steeper when the rewards were delayed--hence, finding an amount effect with delay discounting.

  9. Recovery of iron oxides from acid mine drainage and their application as adsorbent or catalyst.

    PubMed

    Flores, Rubia Gomes; Andersen, Silvia Layara Floriani; Maia, Leonardo Kenji Komay; José, Humberto Jorge; Moreira, Regina de Fatima Peralta Muniz

    2012-11-30

    Iron oxide particles recovered from acid mine drainage represent a potential low-cost feedstock to replace reagent-grade chemicals in the production of goethite, ferrihydrite or magnetite with relatively high purity. Also, the properties of iron oxides recovered from acid mine drainage mean that they can be exploited as catalysts and/or adsorbents to remove azo dyes from aqueous solutions. The main aim of this study was to recover iron oxides with relatively high purity from acid mine drainage to act as a catalyst in the oxidation of dye through a Fenton-like mechanism or as an adsorbent to remove dyes from an aqueous solution. Iron oxides (goethite) were recovered from acid mine drainage through a sequential precipitation method. Thermal treatment at temperatures higher than 300 °C produces hematite through a decrease in the BET area and an increase in the point of zero charge. In the absence of hydrogen peroxide, the solids adsorbed the textile dye Procion Red H-E7B according to the Langmuir model, and the maximum amount adsorbed decreased as the temperature of the thermal treatment increased. The decomposition kinetics of hydrogen peroxide is dependent on the H(2)O(2) concentration and iron oxides dosage, but the second-order rate constant normalized to the BET surface area is similar to that for different iron oxides tested in this and others studies. These results indicate that acid mine drainage could be used as a source material for the production of iron oxide catalysts/adsorbents, with comparable quality to those produced using analytical-grade reagents.

  10. Carbonaceous adsorbent regeneration and halocarbon displacement by hydrocarbon gases

    DOEpatents

    Senum, G.I.; Dietz, R.N.

    1994-04-05

    This invention describes a process for regeneration of halocarbon bearing carbonaceous adsorbents through which a carbonaceous adsorbent is contacted with hydrocarbon gases, preferably propane, butane and pentane at near room temperatures and at atmospheric pressure. As the hydrocarbon gases come in contact with the adsorbent, the hydrocarbons displace the halocarbons by physical adsorption. As a result of using this process, the halocarbon concentration and the hydrocarbon eluant is increased thereby allowing for an easier recovery of pure halocarbons. By using the process of this invention, carbonaceous adsorbents can be regenerated by an inexpensive process which also allows for subsequent re-use of the recovered halocarbons. 8 figures.

  11. Carbonaceous adsorbent regeneration and halocarbon displacement by hydrocarbon gases

    DOEpatents

    Senum, Gunnar I.; Dietz, Russell N.

    1994-01-01

    This invention describes a process for regeneration of halocarbon bearing carbonaceous adsorbents through which a carbonaceous adsorbent is contacted with hydrocarbon gases, preferably propane, butane and pentane at near room temperatures and at atmospheric pressure. As the hydrocarbon gases come in contact with the adsorbent, the hydrocarbons displace the halocarbons by physical adsorption. As a result of using this process, the halocarbon concentration and the hydrocarbon eluant is increased thereby allowing for an easier recovery of pure halocarbons. By using the process of this invention, carbonaceous adsorbents can be regenerated by an inexpensive process which also allows for subsequent re-use of the recovered halocarbons.

  12. Testing of chemically treated adsorbent air purifiers

    SciTech Connect

    Kelly, T.J. . Dept. of Atmospheric Science and Applied Technology); Kinkead, D.A. )

    1993-07-01

    New highly sensitive continuous monitors permit testing of air filters at parts-per-billion contaminant concentrations. This article describes testing of air purification filters intended for use in the National Archives 2 building in College Park, Maryland, using a test procedure that simulates the actual conditions of use. This test demonstrates both the effectiveness of the adsorbers at low contaminant levels, and the capability of existing instruments for conducting such tests. ASHRAE TC 2.3 (Gaseous Air Contaminants and Gas Contaminant Removal Equipment) is currently sponsoring research projects (follow-on studies to ASHRAE Project RP-674) aimed at developing a standard that will test and rate the performance of different types of gas phase air purification equipment at low concentrations. The work detailed in this article represents a first of this type of testing and a technical benchmark that may aid in the further development of ASHRAE gas phase performance standards.

  13. The condensation of water on adsorbed viruses.

    PubMed

    Alonso, José María; Tatti, Francesco; Chuvilin, Andrey; Mam, Keriya; Ondarçuhu, Thierry; Bittner, Alexander M

    2013-11-26

    The wetting and dewetting behavior of biological nanostructures and to a greater degree single molecules is not well-known even though their contact with water is the basis for all biology. Here, we show that environmental electron microscopy (EM) can be applied as a means of imaging the condensation of water onto viruses. We captured the formation of submicrometer water droplets and filaments on single viral particles by environmental EM and by environmental transmission EM. The condensate structures are compatible with capillary condensation between adsorbed virus particles and with known droplet shapes on patterned surfaces. Our results confirm that such droplets exist down to <50 nm. The viruses preserved their shape after a condensation/evaporation cycle as expected from their stability in air and water. Moreover we developed procedures that overcome problems of beam damage and of resolving structures with a low atomic number.

  14. Carbon Dioxide Capture Adsorbents: Chemistry and Methods.

    PubMed

    Patel, Hasmukh A; Byun, Jeehye; Yavuz, Cafer T

    2016-12-21

    Excess carbon dioxide (CO2 ) emissions and their inevitable consequences continue to stimulate hard debate and awareness in both academic and public spaces, despite the widespread lack of understanding on what really is needed to capture and store the unwanted CO2 . Of the entire carbon capture and storage (CCS) operation, capture is the most costly process, consisting of nearly 70 % of the price tag. In this tutorial review, CO2 capture science and technology based on adsorbents are described and evaluated in the context of chemistry and methods, after briefly introducing the current status of CO2 emissions. An effective sorbent design is suggested, whereby six checkpoints are expected to be met: cost, capacity, selectivity, stability, recyclability, and fast kinetics.

  15. Trends in adsorbate induced core level shifts

    NASA Astrophysics Data System (ADS)

    Nilsson, Viktor; Van den Bossche, Maxime; Hellman, Anders; Grönbeck, Henrik

    2015-10-01

    Photoelectron core level spectroscopy is commonly used to monitor atomic and molecular adsorption on metal surfaces. As changes in the electron binding energies are convoluted measures with different origins, calculations are often used to facilitate the decoding of experimental signatures. The interpretation could in this sense benefit from knowledge on trends in surface core level shifts for different metals and adsorbates. Here, density functional theory calculations have been used to systematically evaluate core level shifts for (111) and (100) surfaces of 3d, 4d, and 5d transition metals upon CO, H, O and S adsorption. The results reveal trends and several non-intuitive cases. Moreover, the difficulties correlating core level shifts with charging and d-band shifts are underlined.

  16. Interaction of sodium polyacrylate adsorbed on TiO2 with cationic and anionic surfactants.

    PubMed

    Li, Haiyan; Tripp, Carl P

    2004-11-23

    Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) was used to identify the structures formed during the adsorption of sodium polyacrylate (NaPA) on charged TiO2 particles and to determine the subsequent interaction of the adsorbed polymer structure with cationic and anionic surfactants. The nature of the polymer structure was deduced from the adsorbed amount in tandem with the information obtained from monitoring the change in the relative intensity of the COO- and COOH infrared bands. In particular, it is found that the relative number of COO- and COOH groups on the polymer backbone for the adsorbed state differs from that of the same polymer in solution. This difference is due to a shift in the population of COO-/COOH groups on the polymer backbone that arises when the COO- groups bind to positively charged sites on the surface. A change in the number COO-/COOH groups on the polymer is thus related to a change in the bound fraction of polymer. It is shown that the initial NaPA approaching the bare surface adopts a flat conformation with high bound fraction. Once the bare sites on the surface are covered, the accommodation of additional polymer on the surface requires the existing adsorbed layer to adopt a conformation with a lower bound fraction. When the adsorbed NaPA is probed with a solution containing the anionic surfactant sodium dodecyl sulfate (SDS), the SDS competes for surface sites and displaces some of the bound NaPA segments from the surface, giving rise to an polymer layer adsorbed with an even lower bound fraction. In contrast, addition of a solution containing the cationic surfactant cetyltrimethylammonium bromide (CTAB) results in the binding of the surfactant directly to the free COO- sites on the adsorbed polymer backbone. Confirmation of a direct interaction of the CTAB headgroup with the free COO- groups of the polymer is provided by intensity changes in the headgroup IR bands of the CTAB.

  17. Atmospheric fate of oil matter adsorbed on sea salt particles under UV light

    NASA Astrophysics Data System (ADS)

    Vaitilingom, M.; Avij, P.; Huang, H.; Valsaraj, K. T.

    2014-12-01

    The presence of liquid petroleum hydrocarbons at the sea water surface is an important source of marine pollution. An oil spill in sea-water will most likely occur due to an involuntary accident from tankers, offshore platforms, etc. However, a large amount of oil is also deliberately spilled in sea-water during the clean-out process of tank vessels (e.g. for the Mediterranean Sea, 490,000 tons/yr). Moreover, the pollution caused by an oil spill does not only affect the aquatic environment but also is of concern for the atmospheric environment. A portion of the oil matter present at the sea-water surface is transported into the atmosphere viaevaporation and adsorption at the surface of sea spray particles. Few studies are related to the presence of oil matter in airborne particles resulting from their adsorption on sea salt aerosols. We observed that the non-volatile oil matter was adsorbed at the surface of sea-salt crystals (av. size of 1.1 μm). Due to their small size, these particles can have a significant residence time in the atmosphere. The hydrocarbon matter adsorbed at the surface of these particles can also be transformed by catalyzers present in the atmosphere (i.e. UV, OH, O3, ...). In this work, we focused on the photo-oxidation rates of the C16 to C30alkanes present in these particles. We utilized a bubble column reactor, which produced an abundance of small sized bubbles. These bubbles generated droplets upon bursting at the air-salt water interface. These droplets were then further dried up and lifted to the top of the column where they were collected as particles. These particles were incubated in a controlled reactor in either dark conditions or under UV-visible light. The difference of alkane content analyzed by GC-MS between the particles exposed to UV or the particles not exposed to UV indicated that up to 20% in mass was lost after 20 min of light exposure. The degradation kinetics varied for each range of alkanes (C16-20, C21-25, C26

  18. Morin Flavonoid Adsorbed on Mesoporous Silica, a Novel Antioxidant Nanomaterial.

    PubMed

    Arriagada, Francisco; Correa, Olosmira; Günther, Germán; Nonell, Santi; Mura, Francisco; Olea-Azar, Claudio; Morales, Javier

    2016-01-01

    Morin (2´,3, 4´,5,7-pentahydroxyflavone) is a flavonoid with several beneficial health effects. However, its poor water solubility and it sensitivity to several environmental factors avoid its use in applications like pharmaceutical and cosmetic. In this work, we synthetized morin-modified mesoporous silica nanoparticles (AMSNPs-MOR) as useful material to be used as potential nanoantioxidant. To achieve this, we characterized its adsorption kinetics, isotherm and the antioxidant capacity as hydroxyl radical (HO•) scavenger and singlet oxygen (1O2) quencher. The experimental data could be well fitted with Langmuir, Freundlich and Temkin isotherm models, besides the pseudo-second order kinetics model. The total quenching rate constant obtained for singlet oxygen deactivation by AMSNPs-MOR was one order of magnitude lower than the morin rate constant reported previously in neat solvents and lipid membranes. The AMSNPs-MOR have good antioxidant properties by itself and exhibit a synergic effect with morin on the antioxidant property against hydroxyl radical. This effect, in the range of concentrations studied, was increased when the amount of morin adsorbed increased.

  19. Morin Flavonoid Adsorbed on Mesoporous Silica, a Novel Antioxidant Nanomaterial

    PubMed Central

    Arriagada, Francisco; Correa, Olosmira; Günther, Germán; Nonell, Santi; Mura, Francisco; Olea-Azar, Claudio

    2016-01-01

    Morin (2´,3, 4´,5,7-pentahydroxyflavone) is a flavonoid with several beneficial health effects. However, its poor water solubility and it sensitivity to several environmental factors avoid its use in applications like pharmaceutical and cosmetic. In this work, we synthetized morin-modified mesoporous silica nanoparticles (AMSNPs-MOR) as useful material to be used as potential nanoantioxidant. To achieve this, we characterized its adsorption kinetics, isotherm and the antioxidant capacity as hydroxyl radical (HO•) scavenger and singlet oxygen (1O2) quencher. The experimental data could be well fitted with Langmuir, Freundlich and Temkin isotherm models, besides the pseudo-second order kinetics model. The total quenching rate constant obtained for singlet oxygen deactivation by AMSNPs-MOR was one order of magnitude lower than the morin rate constant reported previously in neat solvents and lipid membranes. The AMSNPs-MOR have good antioxidant properties by itself and exhibit a synergic effect with morin on the antioxidant property against hydroxyl radical. This effect, in the range of concentrations studied, was increased when the amount of morin adsorbed increased. PMID:27812111

  20. Structures of multidomain proteins adsorbed on hydrophobic interaction chromatography surfaces.

    PubMed

    Gospodarek, Adrian M; Sun, Weitong; O'Connell, John P; Fernandez, Erik J

    2014-12-05

    In hydrophobic interaction chromatography (HIC), interactions between buried hydrophobic residues and HIC surfaces can cause conformational changes that interfere with separations and cause yield losses. This paper extends our previous investigations of protein unfolding in HIC chromatography by identifying protein structures on HIC surfaces under denaturing conditions and relating them to solution behavior. The thermal unfolding of three model multidomain proteins on three HIC surfaces of differing hydrophobicities was investigated with hydrogen exchange mass spectrometry (HXMS). The data were analyzed to obtain unfolding rates and Gibbs free energies for unfolding of adsorbed proteins. The melting temperatures of the proteins were lowered, but by different amounts, on the different surfaces. In addition, the structures of the proteins on the chromatographic surfaces were similar to the partially unfolded structures produced in the absence of a surface by temperature as well as by chemical denaturants. Finally, it was found that patterns of residue exposure to solvent on different surfaces at different temperatures can be largely superimposed. These findings suggest that protein unfolding on various HIC surfaces might be quantitatively related to protein unfolding in solution and that details of surface unfolding behavior might be generalized.

  1. Surfactant-modified montmorillonite as a nanosized adsorbent for removal of an insecticide: kinetic and isotherm studies.

    PubMed

    Hassani, Aydin; Khataee, Alireza; Karaca, Semra; Shirzad-Siboni, Mehdi

    2015-01-01

    Surfactant-modified montmorillonites (MMT) were prepared using trimethyloctylammonium bromide (TMOAB) and employed as a nanosized adsorbent to remove diazinon from aqueous solutions. The prepared adsorbent was characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). The dependence of removal efficiency on initial diazinon concentration, amount of adsorbent, pH of the solution and ionic strength was investigated. The affinity sequence for ion adsorption on TMOAB/MMT was in the order: without anion> sodium carbonate> sodium bicarbonate> sodium sulphate> sodium chloride. The adsorption kinetic and isotherm were best fit by a pseudo-second-order kinetic and Langmuir isotherm models, respectively.

  2. Formation Process of Eosin Y-Adsorbing ZnO Particles by Electroless Deposition and Their Photoelectric Conversion Properties.

    PubMed

    Nagaya, Satoshi; Nishikiori, Hiromasa; Mizusaki, Hideaki; Wagata, Hajime; Teshima, Katsuya

    2015-06-03

    The thin films consisting of crystalline ZnO particles were prepared on fluorine-doped tin oxide electrodes by electroless deposition. The particles were deposited from an aqueous solution containing zinc nitrate, dimethyamine-borane, and eosin Y at 328 K. As the Pd particles were adsorbed on the substrate, not only the eosin Y monomer but also the dimer and debrominated species were rapidly adsorbed on the spherical ZnO particles, which were aggregated and formed secondary particles. On the other hand, in the absence of the Pd particles, the monomer was adsorbed on the flake-shaped ZnO particles, which vertically grew on the substrate surface and had a high crystallinity. The photoelectric conversion efficiency was higher for the ZnO electrodes containing a higher amount of the monomer during light irradiation.

  3. A review on modification methods to cellulose-based adsorbents to improve adsorption capacity.

    PubMed

    Hokkanen, Sanna; Bhatnagar, Amit; Sillanpää, Mika

    2016-03-15

    In recent decades, increased domestic, agricultural and industrial activities worldwide have led to the release of various pollutants, such as toxic heavy metals, inorganic anions, organics, micropollutants and nutrients into the aquatic environment. The removal of these wide varieties of pollutants for better quality of water for various activities is an emerging issue and a robust and eco-friendly treatment technology is needed for the purpose. It is well known that cellulosic materials can be obtained from various natural sources and can be employed as cheap adsorbents. Their adsorption capacities for heavy metal ions and other aquatic pollutants can be significantly affected upon chemical treatment. In general, chemically modified cellulose exhibits higher adsorption capacities for various aquatic pollutants than their unmodified forms. Numerous chemicals have been used for cellulose modifications which include mineral and organic acids, bases, oxidizing agent, organic compounds, etc. This paper reviews the current state of research on the use of cellulose, a naturally occurring material, its modified forms and their efficacy as adsorbents for the removal of various pollutants from waste streams. In this review, an extensive list of various cellulose-based adsorbents from literature has been compiled and their adsorption capacities under various conditions for the removal of various pollutants, as available in the literature, are presented along with highlighting and discussing the key advancement on the preparation of cellulose-based adsorbents. It is evident from the literature survey presented herein that modified cellulose-based adsorbents exhibit good potential for the removal of various aquatic pollutants. However, still there is a need to find out the practical utility of these adsorbents on a commercial scale, leading to the improvement of pollution control.

  4. 45 CFR 32.8 - Amounts withheld.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... paragraph (b) of this section. The employer may use the SF-329C “Wage Garnishment Worksheet” to calculate... garnishment order up to 15% of the debtor's disposable pay; or (2) The amount set forth in 15 U.S.C. 1673(a)(2) (Maximum allowable garnishment). The amount set forth at 15 U.S.C. 1673(a)(2) is the amount by which...

  5. 45 CFR 32.8 - Amounts withheld.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... paragraph (b) of this section. The employer may use the SF-329C “Wage Garnishment Worksheet” to calculate... garnishment order up to 15% of the debtor's disposable pay; or (2) The amount set forth in 15 U.S.C. 1673(a)(2) (Maximum allowable garnishment). The amount set forth at 15 U.S.C. 1673(a)(2) is the amount by which...

  6. [Leaf micro-morphology and features in adsorbing air suspended particulate matter and accumulating heavy metals in seven trees species].

    PubMed

    Liu, Ling; Fang, Yan-Ming; Wang, Shun-Chang; Xie, Ying; Yang, Dan-Dan

    2013-06-01

    The purpose of this study was to assess the relationship between tree leaf micro-morphology and features in adsorbing air suspended particulate matter and accumulating heavy metals. Seven tree species, including Ginkgo biloba, at heavy traffic density site in Huainan were selected to analyze the frequency of air particulate matter retained by leaves, the particle amount of different sizes per unit leaf area retained by leaves and its related micro-morphology structure, and the relationship between particle amount of different sizes per unit leaf area retained by leaves and its related accumulation of heavy metals. We found that the species characterized by small leaf area, special epidemis with abundant fax, and highly uneven cell wall, as well as big and dense stomata and without trichomes mainly absorbed fine particulate matter; while those species with many trichomes mainly retained coarse particulate matter. Accumulation of heavy metals in leaves of the seven species was significantly different except for Ph. Tree species with high capacities in heavy metal accumulation were Ginkgo biloba, Ligustrum lucidum, and Cinnamomum camphora. Accumulation of Cd, Cr, Ni, Zn, Cu and total heavy metal concentration for seven tree species was positively related to the amount of particulate matter absorbed. Correlation coefficients of d10 vs d2.5, d10 vs d1.0, d2.5 vs d1.0 were 0.987, 0.971, 0.996, respective, and the correlate level was significant. The ratios of d2.5/d10, d1.0/d10, d1.0/d2.5 were 0.844, 0.763, 0.822, indicating that the particulate matter from traffic was mainly fine particulates.

  7. Determination of surface properties of iron hydroxide-coated alumina adsorbent prepared for removal of arsenic from drinking water.

    PubMed

    Hlavay, József; Polyák, Klára

    2005-04-01

    A novel type adsorbent was prepared by in situ precipitation of Fe(OH)3 on the surface of activated Al2O3 as a support material. The iron content of the adsorbent was 0.31+/-0.003% m/m (56.1 mmol/g); its mechanical and chemical stability proved to be appropriate in solutions. The total capacity of the adsorbent was 0.12 mmol/g, and the pH of zero point of charge, pH(zpc) = 6.9+/-0.3. Depending on the pH of solutions, the adsorbent can be used for binding of both anions and cations, if pH(eq) < pH(zpc) anions are sorbed on the surface of adsorbent (S) through [SOH2+] and [SOH] groups. A graphical method was used for the determination of pH(iep) (isoelectric points) of the adsorbent and values of pH(iep) = 6.1+/-0.3 for As(III) and pH(iep) = 8.0+/-0.3 for As(V) ions were found. The amount of surface charged groups (Q) was about zero within the a pH range of 6.5-8.6, due to the practically neutral surface formed on the adsorption of As(V) ions. At acidic pH (pH 4.7), Q = 0.19 mol/kg was obtained. The adsorption of arsenate and arsenite ions from solutions of 0.1-0.4 mmol/L was represented by Langmuir-type isotherms. A great advantage of the adsorbent is that it can be used in adsorption columns, and low waste technology for removal of arsenic from drinking water can be developed.

  8. Bioavailability of adsorbed and coprecipitated Cu, Ni, Pb, and Cd on iron and iron/aluminum hydroxide to Phragmites australis.

    PubMed

    Wang, He; Jia, Yongfeng

    2017-01-01

    The bioavailability of heavy metals strongly depends on their speciation in the environment. Adsorption (ADS) and coprecipitation (CPT) on amorphous metal hydroxides are important processes, controlling the fates of heavy metals in an aqueous environment. This work studied the bioavailability of Cu, Cd, Ni, and Pb adsorbed on and/or coprecipitated with amorphous iron and iron/aluminum mixed hydroxides to the wetland plant Phragmites australis. After a 13-day treatment, there was an apparent uptake of the heavy metals by the plant, and the amount of metal bioaccumulation was measurably different for different association forms (ADS vs. CPT). The bioaccumulation of Cd associated with Fe0.5Al0.5(OH)3 was greater than that with Fe(OH)3; the adsorbed metals were found to be more bioavailable than the coprecipitated forms for most of the treatments while the aging treatment significantly reduced the bioaccumulation of ADS metals. In the single metal treatment, root metal concentrations in the Fe(OH)3 ADS system followed the order Ni (68 mg kg(-1)) > Cu (32 mg kg(-1)) > Cd (28 mg kg(-1)) > Pb (9 mg kg(-1)), while the CPT system followed the order of Cu (30 mg kg(-1)) > Ni (22 mg kg(-1)) > Pb (9 mg kg(-1)) > Cd (7 mg kg(-1)). The order of metal accumulation in a combined metal treatment was similar to that for single metal treatments, but observed Ni concentration declines by 22 and 71 % and Cu and Cd concentrations increase by 30 and 50 % (for CPT and ADS treatments, respectively), while Pb concentrations increased by 30~50 % in both of them. When treated with low-molecular-weight organic acids (LMWOAs), metal desorption, indicative of metal oxide bonding strength and metal bioavailability, was consistent with metal accumulation in the plant.

  9. High-efficiency DALI apheresis using 1,250 ml adsorbers in a hypercholesterolemic obese patient: a case report.

    PubMed

    Bosch, T; Lennertz, A; Samtleben, W

    2001-10-01

    Direct adsorption of lipoproteins (DALI) apheresis is the first method for direct adsorption of lipoproteins from whole blood and is therefore an easy and rapid procedure. The majority of patients reaches >60% acute low-density lipoprotein cholesterol (LDL-C) reduction using either the DALI 750 or 1000 configuration. However, in patients with extremely high LDL-C levels or very large blood volumes, these configurations may lead to suboptimal results. The current study was performed to test the safety and efficacy of DALI 1250. In a severely obese patient (185 cm, 133 kg, blood volume 7.2 L, LDL-C 239 mg/dl), 11 L of blood (1.53-fold patient blood volume) was processed at a flow rate of 80 ml/min in 2.5 h; a combined heparin-plus-citrate anticoagulation regimen was used. Commercially available DALI 1250 and DALI hardware and disposables were manufactured by Fresenius HemoCare Adsorber Technology, St. Wendel, Germany. Twenty weekly sessions were performed. Clinically and technically, the apheresis sessions were completely uneventful. As compared to DALI 1000 (n = 4 sessions), the reduction rates by DALI 1250 (n = 20) improved for LDL-C (from 52% to 66%), lipoprotein (a) (Lp[a]) (53% vs. 66%), and fibrinogen (11% vs. 16%). There was a slight increase in high-density lipoprotein cholesterol (HDL-C) loss (20% vs. 24%). Moreover, the absolute amount of LDL-C removed per session increased from 5.06 g to 5.94 g. Laboratory safety parameters remained within the normal range, the anticoagulation was well controlled, and the pressure gradients over the adsorber remained constant. In this case report, DALI 1250 was perfectly safe and significantly increased the efficacy of LDL-C and Lp(a) elimination compared to standard DALI. Thus, this high-efficiency version of DALI may be used in patients with extremely high LDL-C levels and/or large blood volumes.

  10. A review on applicability of naturally available adsorbents for the removal of hazardous dyes from aqueous waste.

    PubMed

    Sharma, Pankaj; Kaur, Harleen; Sharma, Monika; Sahore, Vishal

    2011-12-01

    The effluent water of many industries, such as textiles, leather, paper, printing, cosmetics, etc., contains large amount of hazardous dyes. There is huge number of treatment processes as well as adsorbent which are available for the processing of this effluent water-containing dye content. The applicability of naturally available low cast and eco-friendly adsorbents, for the removal of hazardous dyes from aqueous waste by adsorption treatment, has been reviewed. In this review paper, we have provided a compiled list of low-cost, easily available, safe to handle, and easy-to-dispose-off adsorbents. These adsorbents have been classified into five different categories on the basis of their state of availability: (1) waste materials from agriculture and industry, (2) fruit waste, (3) plant waste, (4) natural inorganic materials, and (5) bioadsorbents. Some of the treated adsorbents have shown good adsorption capacities for methylene blue, congo red, crystal violet, rhodamine B, basic red, etc., but this adsorption process is highly pH dependent, and the pH of the medium plays an important role in the treatment process. Thus, in this review paper, we have made some efforts to discuss the role of pH in the treatment of wastewater.

  11. Enhanced CO2 adsorptive performance of PEI/SBA-15 adsorbent using phosphate ester based surfactants as additives.

    PubMed

    Cheng, Dandan; Liu, Yue; Wang, Haiqiang; Weng, Xiaole; Wu, Zhongbiao

    2015-12-01

    In this study, a series of polyetherimide/SBA-15: 2-D hexagonal P6mm, Santa Barbara USA (PEI/SBA-15) adsorbents modified by phosphoric ester based surfactants (including tri(2-ethylhexyl) phosphate (TEP), bis(2-ethylhexyl) phosphate (BEP) and trimethyl phosphonoacetate (TMPA)) were prepared for CO2 adsorption. Experimental results indicated that the addition of TEP and BEP had positive effects on CO2 adsorption capacity over PEI/SBA-15. In particular, the CO2 adsorption amount could be improved by around 20% for 45PEI-5TEP/SBA-15 compared to the additive-free adsorbent. This could be attributed to the decrease of CO2 diffusion resistance in the PEI bulk network due to the interactions between TEP and loaded PEI molecules, which was further confirmed by adsorption kinetics results. In addition, it was also found that the cyclic performance of the TEP-modified adsorbent was better than the surfactant-free one. This could be due to two main reasons, based on the results of in situ DRIFT and TG-DSC tests. First and more importantly, adsorbed CO2 species could be desorbed more rapidly over TEP-modified adsorbent during the thermal desorption process. Furthermore, the enhanced thermal stability after TEP addition ensured lower degradation of amine groups during adsorption/desorption cycles.

  12. Development of a new adsorbent from agro-industrial waste and its potential use in endocrine disruptor compound removal.

    PubMed

    Rovani, Suzimara; Censi, Monique T; Pedrotti, Sidnei L; Lima, Eder C; Cataluña, Renato; Fernandes, Andreia N

    2014-04-30

    A new activated carbon (AC) material was prepared by pyrolysis of a mixture of coffee grounds, eucalyptus sawdust, calcium hydroxide and soybean oil at 800°C. This material was used as adsorbent for the removal of the endocrine disruptor compounds 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) from aqueous solutions. The carbon material was characterized by scanning electron microscopy (SEM), infrared spectroscopy (FTIR), N2 adsorption/desorption curves and point of zero charge (pHPZC). Variables including the initial pH of the adsorbate solutions, adsorbent masses and contact time were optimized. The optimum range of initial pH for removal of endocrine disruptor compounds (EDC) was 2.0-11.0. The kinetics of adsorption were investigated using general order, pseudo first-order and pseudo-second order kinetic models. The Sips isotherm model gave the best fits of the equilibrium data (298K). The maximum amounts of E2 and EE2 removed at 298K were 7.584 (E2) and 7.883mgg(-1) (EE2) using the AC as adsorbent. The carbon adsorbent was employed in SPE (solid phase extraction) of E2 and EE2 from aqueous solutions.

  13. Characterization and testing of amidoxime-based adsorbent materials to extract uranium from natural seawater

    DOE PAGES

    Kuo, Li-Jung; Janke, Christopher James; Wood, Jordana; ...

    2015-11-19

    Extraction of uranium (U) from seawater for use as a nuclear fuel is a significant challenge due to the low concentration of U in seawater (~3.3 ppb) and difficulties to selectively extract U from the background of major and trace elements in seawater. The Pacific Northwest National Laboratory (PNNL) s Marine Sciences Laboratory (MSL) has been serving as a marine test site for determining performance characteristics (adsorption capacity, adsorption kinetics, and selectivity) of novel amidoxime-based polymeric adsorbents developed at Oak Ridge National Laboratory (ORNL) under natural seawater exposure conditions. This report describes the performance of three formulations (38H, AF1, AI8)more » of amidoxime-based polymeric adsorbent produced at ORNL in MSL s ambient seawater testing facility. The adsorbents were produced in two forms, fibrous material (40-100 mg samples) and braided material (5-10 g samples), exposed to natural seawater using flow-through columns and recirculating flumes. All three formulations demonstrated high 56 day uranium adsorption capacity (>3 gU/kg adsorbent). The AF1 formulation had the best uranium adsorption performance, with 56-day capacity of 3.9 g U/kg adsorbent, saturation capacity of 5.4 g U/kg adsorbent, and ~25 days half-saturation time. The two exposure methods, flow-through columns and flumes were demonstrated to produce similar performance results, providing confidence that the test methods were reliable, that scaling up from 10 s of mg quantities of exposure in flow-through columns to gram quantities in flumes produced similar results, and that the manufacturing process produces a homogenous adsorbent. Adsorption kinetics appear to be element specific, with half-saturation times ranging from minutes for the major cations in seawater to 8-10weeks for V and Fe. Reducing the exposure time provides a potential pathway to improve the adsorption capacity of U by reducing the V/U ratio on the adsorbent.« less

  14. Manufacturing of agarose-based chromatographic adsorbents--effect of ionic strength and cooling conditions on particle structure and mechanical strength.

    PubMed

    Ioannidis, Nicolas; Bowen, James; Pacek, Andrzej; Zhang, Zhibing

    2012-02-01

    The effect of ionic strength of agarose solution and quenching temperature of the emulsion on the structure and mechanical strength of agarose-based chromatographic adsorbents was investigated. Solutions of agarose containing different amounts of NaCl were emulsified at elevated temperature in mineral oil using a high-shear mixer. The hot emulsion was quenched at different temperatures leading to the gelation of agarose and formation of soft particles. Analysis of Atomic Force Microscopy (AFM) images of particle surfaces shows that pore size of particles increases with ionic strength and/or high quenching temperature. Additionally it has been found that the compressive strength of particles measured by micromanipulation also increases with ionic strength of the emulsion and/or high quenching temperature but these two parameters have no significant effect on the resulting particle size and particle size distribution. Results from both characterization methods were compared with Sepharose 4B, a commercial agarose-based adsorbent. This is the first report examining the effect of ionic strength and cooling conditions on the microstructure of micron-sized agarose beads for bioseparation.

  15. 20 CFR 617.34 - Amount.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... the Federal travel regulations (see 41 CFR part 101-7) for the locality where the job search is... WORKERS UNDER THE TRADE ACT OF 1974 Job Search Allowances § 617.34 Amount. (a) Computation. The amount of a job search allowance shall be 90 percent of the total costs of each of the following...

  16. 20 CFR 617.34 - Amount.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... the Federal travel regulations (see 41 CFR part 101-7) for the locality where the job search is... WORKERS UNDER THE TRADE ACT OF 1974 Job Search Allowances § 617.34 Amount. (a) Computation. The amount of a job search allowance shall be 90 percent of the total costs of each of the following...

  17. 20 CFR 617.34 - Amount.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... the Federal travel regulations (see 41 CFR part 101-7) for the locality where the job search is... WORKERS UNDER THE TRADE ACT OF 1974 Job Search Allowances § 617.34 Amount. (a) Computation. The amount of a job search allowance shall be 90 percent of the total costs of each of the following...

  18. 46 CFR 308.403 - Insured amounts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... total amount of war risk insurance obtainable from companies authorized to do an insurance business in a... authorized to do an insurance business in a State of the United States. (c) Maximum liability. The amount of... MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION EMERGENCY OPERATIONS WAR RISK INSURANCE War...

  19. 46 CFR 308.403 - Insured amounts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... total amount of war risk insurance obtainable from companies authorized to do an insurance business in a... authorized to do an insurance business in a State of the United States. (c) Maximum liability. The amount of... MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION EMERGENCY OPERATIONS WAR RISK INSURANCE War...

  20. 20 CFR 617.34 - Amount.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... WORKERS UNDER THE TRADE ACT OF 1974 Job Search Allowances § 617.34 Amount. (a) Computation. The amount of a job search allowance shall be 90 percent of the total costs of each of the following allowable... job search; or (ii) The cost per mile at the prevailing mileage rate authorized under the...

  1. 46 CFR 308.100 - Insured amount.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION EMERGENCY OPERATIONS WAR RISK INSURANCE War Risk Hull and Disbursements Insurance § 308.100 Insured amount. An applicant for war risk hull insurance shall state the amount of insurance desired but any payment of claim for damage to or actual or...

  2. 23 CFR 1335.8 - Grant amounts.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Grant amounts. 1335.8 Section 1335.8 Highways NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STATE HIGHWAY SAFETY DATA IMPROVEMENTS § 1335.8 Grant amounts. (a) Start-up grant. A State that qualifies for a start-up grant under §...

  3. 23 CFR 1335.8 - Grant amounts.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Grant amounts. 1335.8 Section 1335.8 Highways NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STATE HIGHWAY SAFETY DATA IMPROVEMENTS § 1335.8 Grant amounts. (a) Start-up grant. A State that qualifies for a start-up grant under §...

  4. 13 CFR 400.202 - Loan amount.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ....202 Business Credit and Assistance EMERGENCY STEEL GUARANTEE LOAN BOARD EMERGENCY STEEL GUARANTEE LOAN PROGRAM Steel Guarantee Loans § 400.202 Loan amount. (a) The aggregate amount of loan principal guaranteed under this Program to a single Qualified Steel Company may not exceed $ 250 million. (b) Of...

  5. 13 CFR 400.202 - Loan amount.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ....202 Business Credit and Assistance EMERGENCY STEEL GUARANTEE LOAN BOARD EMERGENCY STEEL GUARANTEE LOAN PROGRAM Steel Guarantee Loans § 400.202 Loan amount. (a) The aggregate amount of loan principal guaranteed under this Program to a single Qualified Steel Company may not exceed $ 250 million. (b) Of...

  6. 13 CFR 400.202 - Loan amount.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ....202 Business Credit and Assistance EMERGENCY STEEL GUARANTEE LOAN BOARD EMERGENCY STEEL GUARANTEE LOAN PROGRAM Steel Guarantee Loans § 400.202 Loan amount. (a) The aggregate amount of loan principal guaranteed under this Program to a single Qualified Steel Company may not exceed $ 250 million. (b) Of...

  7. 13 CFR 400.202 - Loan amount.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ....202 Business Credit and Assistance EMERGENCY STEEL GUARANTEE LOAN BOARD EMERGENCY STEEL GUARANTEE LOAN PROGRAM Steel Guarantee Loans § 400.202 Loan amount. (a) The aggregate amount of loan principal guaranteed under this Program to a single Qualified Steel Company may not exceed $ 250 million. (b) Of...

  8. 13 CFR 400.202 - Loan amount.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ....202 Business Credit and Assistance EMERGENCY STEEL GUARANTEE LOAN BOARD EMERGENCY STEEL GUARANTEE LOAN PROGRAM Steel Guarantee Loans § 400.202 Loan amount. (a) The aggregate amount of loan principal guaranteed under this Program to a single Qualified Steel Company may not exceed $ 250 million. (b) Of...

  9. Metal adsorbent for alkaline etching aqua solutions of Si wafer

    NASA Astrophysics Data System (ADS)

    Tamada, Masao; Ueki, Yuji; Seko, Noriaki; Takeda, Toshihide; Kawano, Shin-ichi

    2012-08-01

    High performance adsorbent is expected to be synthesized for the removal of Ni and Cu ions from strong alkaline solution used in the surface etching process of Si wafer. Fibrous adsorbent was synthesized by radiation-induce emulsion graft polymerization onto polyethylene nonwoven fabric and subsequent amination. The reaction condition was optimized using 30 L reaction vessel and nonwoven fabric, 0.3 m width and 18 m long. The resulting fibrous adsorbent was evaluated by 48 wt% NaOH and KOH contaminated with Ni and Cu ions, respectively. The concentration levels of Ni and Cu ions was reduced to less than 1 μg/kg (ppb) at the flow rate of 10 h-1 in space velocity. The life of adsorbent was 30 times higher than that of the commercialized resin. This novel adsorbent was commercialized as METOLATE® since the ability of adsorption is remarkably higher than that of commercial resin used practically in Si wafer processing.

  10. The role of vdW interactions in coverage dependent adsorption energies of atomic adsorbates on Pt(111) and Pd(111)

    NASA Astrophysics Data System (ADS)

    Thirumalai, Hari; Kitchin, John R.

    2016-08-01

    Adsorption, a fundamental process in heterogeneous catalysis is known to be dependent on the adsorbate-adsorbate and surface-adsorbate bonds. van der Waals (vdW) interactions are one of the types of interactions that have not been examined thoroughly as a function of adsorbate coverage. In this work we quantify the vdW interactions for atomic adsorbates on late transition metal surfaces, and determine how these long range forces affect the coverage dependent adsorption energies. We calculate the adsorption energies of carbon, nitrogen, oxygen, sulfur, fluorine, bromine and chlorine species on Pt(111) and Pd(111) at coverages ranging from 1/4 to 1 ML using the BEEF-vdW functional. We observe that adsorption energies remain coverage dependent, and this coverage dependence is shown to be statistically significant. vdW interactions are found to be coverage dependent, but more significantly, they are found to be dependent on molecular properties such as adsorbate size, and consequently, correlate with the adsorbate effective nuclear charge. We observe that these interactions account for a reduction in the binding energy of the system, due to the destabilizing attractive interactions between the adsorbates which weaken its bond with the surface.

  11. 78 FR 59702 - Medicare Program; Medicare Appeals: Adjustment to the Amount in Controversy Threshold Amounts for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-27

    ...This notice announces the annual adjustment in the amount in controversy (AIC) threshold amounts for Administrative Law Judge (ALJ) hearings and judicial review under the Medicare appeals process. The adjustment to the AIC threshold amounts will be effective for requests for ALJ hearings and judicial review filed on or after January 1, 2014. The calendar year 2014 AIC threshold amounts are......

  12. Milestone Report - Complete New Adsorbent Materials for Marine Testing to Demonstrate 4.5 g-U/kg Adsorbent

    SciTech Connect

    Janke, Christopher James; Das, Sadananda; Oyola, Yatsandra; Mayes, Richard T.; Saito, Tomonori; Brown, Suree; Gill, Gary; Kuo, Li-Jung; Wood, Jordana

    2014-08-01

    This report describes work on the successful completion of Milestone M2FT-14OR03100115 (8/20/2014) entitled, “Complete new adsorbent materials for marine testing to demonstrate 4.5 g-U/kg adsorbent”. This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed two new families of fiber adsorbents that have demonstrated uranium adsorption capacities greater than 4.5 g-U/kg adsorbent after marine testing at PNNL. One adsorbent was synthesized by radiation-induced graft polymerization of itaconic acid and acrylonitrile onto high surface area polyethylene fibers followed by amidoximation and base conditioning. This fiber showed a capacity of 4.6 g-U/kg adsorbent in marine testing at PNNL. The second adsorbent was prepared by atom-transfer radical polymerization of t-butyl acrylate and acrylonitrile onto halide-functionalized round fibers followed by amidoximation and base hydrolysis. This fiber demonstrated uranium adsorption capacity of 5.4 g-U/kg adsorbent in marine testing at PNNL.

  13. Mechanisms for strong adsorption of tetracycline to carbon nanotubes: a comparative study using activated carbon and graphite as adsorbents.

    PubMed

    Ji, Liangliang; Chen, Wei; Duan, Lin; Zhu, Dongqiang

    2009-04-01

    Significant concerns have been raised over the presence of antibiotics including tetracyclines in aquatic environments. We herein studied single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT) as potential effective adsorbents for removal of tetracycline from aqueous solution. In comparison, a nonpolar adsorbate, naphthalene, and two other carbonaceous adsorbents, pulverized activated carbon (AC) and nonporous graphite, were used. The observed adsorbent-to-solution distribution coefficient (Kd, L/kg) of tetracycline was in the order of 10(4)-10(6) L/kg for SWNT, 10(3)-10(4) L/kg for MWNT, 10(3)-10(4) L/kg for AC, and 10(3)-10(5) L/kg for graphite. Upon normalization for adsorbent surface area, the adsorption affinity of tetracycline decreased in the order of graphite/ SWNT > MWNT > AC. The weaker adsorption of tetracycline to AC indicates that for bulky adsorbates adsorption affinity is greatly affected by the accessibility of available adsorption sites. The remarkably strong adsorption of tetracycline to the carbon nanotubes and to graphite can be attributed to the strong adsorptive interactions (van der Waals forces, pi-pi electron-donor-acceptor interactions, cation-pi bonding) with the graphene surface. Complexation between tetracycline and model graphene compounds (naphthalene, phenanthrene, pyrene) in solution phase was verified by ring current-induced 1H NMR upfield chemical shifts of tetracycline moieties.

  14. Feasibility of fullerene waste as carbonaceous adsorbent

    SciTech Connect

    Cleveland, T.G.; Garg, S.; Rixey, W.G.

    1996-03-01

    This note investigates using the waste soot generated in fullerene manufacture as an adsorbent. Both oven-dried and air-activated samples of waste soot are compared with three commercially available powdered activated carbons (PACs): Nuchar-SA, HDH, and Calgon-RC. Three model compounds were chosen for adsorption tests--TCE, Benzene, and Phenol--representing a small branched molecule, a small nonpolar ring molecule, and relatively polar ring molecule. Additionally, the effectiveness of total organic carbon (TOC) removal from wastewater was evaluated. Oven-dried soot performed poorly as compared to the commercial carbons, but activation of the waste soot for 60 min at 450 C in air resulted in an activated carbon (aFWS) with properties similar to those of commercially available PACs. The aFWS performed better than one would predict from the typical characterization measures of iodine number, molasses number, and methylene blue number. The data for phenol suggest some functional groups are created during the activation of the waste soot. These results show that large-scale fullerene manufacturing can be a zero-waste industry, because its primary waste product can be converted into a useful material.

  15. Photoreduction of methylviologen adsorbed on silver

    SciTech Connect

    Feilchenfeld, H.; Chumanov, G.; Cotton, T.M. |

    1996-03-21

    Methylviologen adsorbed on a roughened silver electrode is reduced to its cation radical upon irradiation with laser light at liquid nitrogen temperature. Surface-enhanced Raman scattering (SERS) spectra were obtained with different excitation wavelengths between 406 and 752 nm and compared to those obtained at room temperature in an electrochemical cell under potential control. From two-color experiments, in which one laser frequency was used to generate the radical and a second to excite the SERS spectra, it was determined that radical formation occurs mainly with excitation in the blue spectral region. A comparison of the SERS spectra of the dication and cation radical forms of methylviologen with their solution spectra suggests that the former interacts more strongly with the surface than the latter. The cation radical appears to be stable for several hours in liquid nitrogen but has a short lifetime at room temperature. Two mechanisms for the photoreduction are discussed: plasmon-assisted electron transfer from the metal to the methylviologen dication and formation of a resonance charge transfer complex. The current experimental data are insufficient to determine the particular role of these mechanisms. 23 refs., 9 figs.

  16. Imaging the wave functions of adsorbed molecules.

    PubMed

    Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Soubatch, Serguei; Tautz, F Stefan; Ramsey, Michael G; Puschnig, Peter

    2014-01-14

    The basis for a quantum-mechanical description of matter is electron wave functions. For atoms and molecules, their spatial distributions and phases are known as orbitals. Although orbitals are very powerful concepts, experimentally only the electron densities and -energy levels are directly observable. Regardless whether orbitals are observed in real space with scanning probe experiments, or in reciprocal space by photoemission, the phase information of the orbital is lost. Here, we show that the experimental momentum maps of angle-resolved photoemission from molecular orbitals can be transformed to real-space orbitals via an iterative procedure which also retrieves the lost phase information. This is demonstrated with images obtained of a number of orbitals of the molecules pentacene (C22H14) and perylene-3,4,9,10-tetracarboxylic dianhydride (C24H8O6), adsorbed on silver, which are in excellent agreement with ab initio calculations. The procedure requires no a priori knowledge of the orbitals and is shown to be simple and robust.

  17. The investigation of phenol removal from aqueous solutions by zeolites as solid adsorbents.

    PubMed

    Damjanović, Ljiljana; Rakić, Vesna; Rac, Vladislav; Stošić, Dušan; Auroux, Aline

    2010-12-15

    This work reports results on phenol adsorption from aqueous solutions on synthetic BEA (β) and MFI (ZSM-5) zeolites, studied by heat-flow microcalorimetry. For the sake of comparison, the adsorption was performed on activated carbon, a solid customarily used for removal of phenol from water. The obtained values of heats evolved during phenol adsorption indicate the heterogeneity of active sites present on the investigated systems for the adsorption of phenol. In addition, the amounts of adsorbed pollutant were determined and presented in the form of adsorption isotherms, which were interpreted using Langmuir, Freundlich, Dubinin-Astakov and Sips' equations. The latter was found to express high level of agreement with experimental data. The results obtained in this work reveal that the adsorption of phenol on zeolites depends on both Si/Al ratio and on the pore size. Hydrophobic zeolites that possess higher contents of Si show higher affinities for phenol adsorption. Among investigated zeolites, zeolite β possesses the highest capacity for adsorption of phenol. The possibility of regeneration of used adsorbents was investigated by thermal desorption technique. It has been shown that in the case of β zeolite the majority of adsorbed phenol is easily released in the low temperature region.

  18. Growth and Dissolution of Calcite in the Presence of Adsorbed Stearic Acid.

    PubMed

    Ricci, Maria; Segura, Juan José; Erickson, Blake W; Fantner, Georg; Stellacci, Francesco; Voïtchovsky, Kislon

    2015-07-14

    The interaction of organic molecules with the surface of calcite plays a central role in many geochemical, petrochemical, and industrial processes and in biomineralization. Adsorbed organics, typically fatty acids, can interfere with the evolution of calcite when immersed in aqueous solutions. Here we use atomic force microscopy in liquid to explore in real-time the evolution of the (1014) surface of calcite covered with various densities of stearic acid and exposed to different saline solutions. Our results show that the stearic acid molecules tend to act as "pinning points" on the calcite's surface and slow down the crystal's restructuring kinetics. Depending on the amount of material adsorbed, the organic molecules can form monolayers or bilayer islands that become embedded into the growing crystal. The growth process can also displaces the organic molecules and actively concentrate them into stacked multilayers. Our results provide molecular-level insights into the interplay between the adsorbed fatty acid molecules and the evolving calcite crystal, highlighting mechanisms that could have important implications for several biochemical and geochemical processes and for the oil industry.

  19. Preparation and evaluation of Ricinus communis agglutinin affinity adsorbents using polymeric supports.

    PubMed

    Cartellieri, S; Helmholz, H; Niemeyer, B

    2001-08-01

    A practicable and efficient procedure for preparation of Ricinus communis agglutinin (RCA) affinity adsorbents has been developed. For immobilization of RCA two different polymer-based supports, Toyopearl and TSKgel (TosoHaas), were used. RCA has been successfully immobilized onto these supports with amounts of coupled ligand between 15 and 23 mg/g dry support and corresponding coupling yields of 69-93% (w/w). The prepared affinity adsorbents were characterized concerning their binding capacity for the glycoprotein asialofetuin (ASF) and accessibility of the ligand binding sites. The high accessibility of 80% showed that steric hindrance was negligible at the present ligand density. RCA-Toyopearl was successfully applied in affinity chromatography of glycoproteins indicating its high specificity. A long-term stability test proved no change in capacity for a period of at least 12 months. High-performance affinity chromatography (HPLAC) was carried out using RCA-TSKgel. Experimental results showed that the prepared adsorbents are suitable for selective separation of glycoproteins and oligosaccharides and therefore can be used for investigations of adsorption characteristics of glycoconjugates and for laboratory-scale preparations.

  20. Removal and recovery of phosphorus in wastewater by superconducting high gradient magnetic separation with ferromagnetic adsorbent

    NASA Astrophysics Data System (ADS)

    Ishiwata, T.; Miura, O.; Hosomi, K.; Shimizu, K.; Ito, D.; Yoda, Y.

    2010-11-01

    Prevention of eutrophication for semi-enclosed bays and ponds is serious and important challenge. In spite of the advanced wastewater treatment, typically 1 mg/L phosphorus is discharged into public water bodies from wastewater treatment plants. The total amount of the discharged water is so large that the further improvement of the removal efficiency of phosphorus in the discharged water is demanded. On the other hand, recently phosphorus has become increasingly recognized as the important strategic material due to the global food problem. Therefore, the recovery and recycling of phosphorus is also important issue. In this work, removal and recovery of phosphorus from treated wastewater by High Gradient Magnetic Separation (HGMS) with ferromagnetic zirconium ferrite adsorbent were studied. Phosphorus in the treated wastewater could be removed from 1.12 mg/L to 0.03 mg/L by the HGMS system with 500 mg/L zirconium ferrite adsorbent for 5 min in adsorption time. The magnetic separation speed achieved 1 m/s at 1 T which was necessary for practical use. We also confirmed that phosphorus could be desorbed from zirconium ferrite adsorbent by alkali treatment in a short time.

  1. Alternative Alkaline Conditioning of Amidoxime Based Adsorbent for Uranium Extraction from Seawater

    SciTech Connect

    Das, S.; Liao, W. -P.; Flicker Byers, M.; Tsouris, C.; Janke, C. J.; Mayes, R. T.; Schneider, E.; Kuo, L. -J.; Wood, J. R.; Gill, G. A.; Dai, S.

    2016-04-20

    Alkaline conditioning of the amidoxime based adsorbents is a significant step in the preparation of the adsorbent for uranium uptake from seawater. The effects of various alkaline conditioning parameters such as the type of alkaline reagent, reaction temperature, and reaction time were investigated with respect to uranium adsorption capacity from simulated seawater (spiked with 8 ppm uranium) and natural seawater (from Sequim Bay, WA). An adsorbent (AF1) was prepared at the Oak Ridge National Laboratory by radiation-induced graft polymerization (RIGP) with acrylonitrile and itaconic acid onto high-surface-area polyethylene fibers. For the AF1 adsorbent, sodium hydroxide emerged as a better reagent for alkaline conditioning over potassium hydroxide, which has typically been used in previous studies, because of higher uranium uptake capacity and lower cost over the other candidate alkaline reagents investigated in this study. Use of sodium hydroxide in place of potassium hydroxide is shown to result in a 21-30% decrease in the cost of uranium recovery.

  2. Chemisorption on surfaces — an historical look at a representative adsorbate: carbon monoxide

    NASA Astrophysics Data System (ADS)

    Yates, John T.

    1994-01-01

    The study of the interaction of molecules with clean surfaces extends back to the work of Irving Langmuir. In this historical account, the development of selected experimental methods for the study of molecular adsorption will be discussed. This will be done by historically reviewing research on one of the most well-studied adsorbate molecules, carbon monoxide. Many of the modern surface science techniques have first been used to study chemisorbed carbon monoxide, and the CO molecule is employed even today as a test molecule for currently developing surface measurement instruments such as the low temperature STM. In addition to being a good test molecule for new surface measurement techniques, adsorbed carbon monoxide is one of the centrally important molecules in the field of heterogeneous catalysis where the production of synthetic fuels and useful organic molecules often depends on the catalytic behavior of the adsorbed CO molecule. Interestingly, the carbon monoxide molecule also serves as a bridge between surface chemistry on the transition metals and the field of organometallic chemistry. Concepts about the chemical bonding and the reactive behavior of CO chemisorbed on transition metal surfaces and CO bound in transition metal carbonyls link these two fields together in a significant manner. The carbon monoxide molecule has been the historical focal point of many endeavors in surface chemistry and surface physics, and research on adsorbed carbon monoxide well represents many of the key advances which characterize the first thirty years of the development of surface science.

  3. Enhanced adsorption of phenol from water by a novel polar post-crosslinked polymeric adsorbent.

    PubMed

    Zeng, Xiaowei; Fan, Yunge; Wu, Guolin; Wang, Chunhong; Shi, Rongfu

    2009-09-30

    A novel post-crosslinked polymeric adsorbent PDM-2 was prepared by Friedel-Crafts reaction of pendant vinyl groups without external crosslinking agent. Both the specific surface area and the pore volume of starting copolymer PDM-1 increased significantly after post-crosslinking. Batch adsorption runs of phenol from aqueous solution onto PDM-1 and PDM-2 were investigated. Commercial macroporous resins XAD-4 and AB-8 were chosen as the comparison. Experimental results showed that isotherms of phenol adsorption onto these four polymeric adsorbents could be represented by Freundlich model reasonably. PDM-2 exhibited higher adsorption capacity of phenol than other three adsorbents, which resulted from synergistic effect of larger specific surface area and polar groups on the network. The adsorption process for phenol was proved to be exothermic and spontaneous in nature. Thermodynamic parameters such as Gibb's free energy (DeltaG), change in enthalpy (DeltaH) and change in entropy (DeltaS) were calculated. Kinetics studies indicated that phenol uptake onto PDM-1 and PDM-2 followed the pseudo-second order model and the intraparticle diffusion process was a rate-controlling step. Column adsorption runs demonstrated that nearly 100% regeneration efficiency for PDM-2 by 3BV industrial alcohol and the adsorbate phenol can be easily recovered by further distilling. Continuous column adsorption-regeneration cycles indicated negligible capacity loss of PDM-2 during operation.

  4. Alternative alkaline conditioning of amidoxime based adsorbent for uranium extraction from seawater

    DOE PAGES

    Das, Sadananda; Liao, Wei -Po; Byers, Maggie Flicker; ...

    2015-10-18

    Alkaline conditioning of the amidoxime based adsorbents is a significant step in the preparation of the adsorbent for uranium uptake from seawater. The effects of various alkaline conditioning parameters such as the type of alkaline reagent, reaction temperature, and reaction time were investigated with respect to uranium adsorption capacity from simulated seawater (spiked with 8 ppm uranium) and natural seawater (from Sequim Bay, WA). An adsorbent (AF1) was prepared at the Oak Ridge National Laboratory by radiation-induced graft polymerization (RIGP) with acrylonitrile and itaconic acid onto high-surface-area polyethylene fibers. For the AF1 adsorbent, sodium hydroxide emerged as a better reagentmore » for alkaline conditioning over potassium hydroxide, which has typically been used in previous studies, because of higher uranium uptake capacity and lower cost over the other candidate alkaline reagents investigated in this study. Furthermore, the use of sodium hydroxide in place of potassium hydroxide is shown to result in a 21–30% decrease in the cost of uranium recovery.« less

  5. Removal of heavy metal ions from aqueous solution using red loess as an adsorbent.

    PubMed

    Xing, Shengtao; Zhao, Meiqing; Ma, Zichuan

    2011-01-01

    The adsorption behaviors of heavy metals onto novel low-cost adsorbent, red loess, were investigated. Red loess was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectra. The results indicated that red loess mainly consisted of silicate, ferric and aluminum oxides. Solution pH, adsorbent dosage, initial metal concentration, contact time and temperature significantly influenced the efficiency of heavy metals removal. The adsorption reached equilibrium at 4 hr, and the experimental equilibrium data were fitted to Langmuir monolayer adsorption model. The adsorption of Cu(II) and Zn(II) onto red loess was endothermic, while the adsorption of Pb(II) was exothermic. The maximum adsorption capacities of red loess for Pb(II), Cu(II) and Zn(II) were estimated to be 113.6, 34.2 and 17.5 mg/g, respectively at 25 degrees C and pH 6. The maximum removal efficiencies were 100% for Pb(II) at pH 7, 100% for Cu(II) at pH 8, and 80% for Zn(II) at pH 8. The used adsorbents were readily regenerated using dilute HCl solution, indicating that red loess has a high reusability. All the above results demonstrated that red loess could be used as a possible alternative low-cost adsorbent for the removal of heavy metals from aqueous solution.

  6. Synthesis and Characterization of Novel Sulfur-Functionalized Silica Gels as Mercury Adsorbents

    NASA Astrophysics Data System (ADS)

    Johari, Khairiraihanna; Saman, Norasikin; Mat, Hanapi

    2014-03-01

    This paper describes the synthesis, functionalization, and characterization of silica gels as mercury adsorbents. The synthesis was carried out according to the modified Stöber method using tetraethyl orthosilicate [TEOS], 3-mercaptopropyl trimethoxysilane [MPTMS] and bis(triethoxysilylpropyl) tetrasulfide [BTEPST] as precursors. The functionalization was carried out via co-condensation and impregnation methods using MPTMS, BTESPT, elemental sulfur [ES], and carbon disulfide [CS2] as sulfur ligands. The choice of the sulfur ligands as precursors and functionalization agents was due to the existence of sulfur active groups in their molecular structures which were expected to have high affinity toward Hg(II) ions. The synthesized adsorbents were characterized by using scanning electron microscope, fourier transform infrared spectrophotometer, nitrogen adsorption/desorption, and energy dispersive X-ray diffractometer. The batch Hg(II) adsorption experiments were employed to evaluate the Hg(II) adsorption performances of the synthesized adsorbents under different pH values. The results revealed that the highest Hg(II) adsorption capacity was obtained for the SG-MPTMS(10) which was 47.83 mg/g at pH 8.5. In general, the existence of sulfur functional groups, especially MPTMS in the silica matrices, gave a significant enhancement of Hg(II) adsorption capacity and the sulfur functionalization via co-condensation method, which is potential as a superior approach in the mercury adsorbent synthesis.

  7. Adsorption of prototypical amino acids on silica: Influence of the pre-adsorbed water multilayer

    NASA Astrophysics Data System (ADS)

    Remesal, Elena R.; Amaya, Javier; Graciani, Jesús; Márquez, Antonio M.; Sanz, Javier Fdez.

    2016-04-01

    We explore the interaction between acetic acid, some typical α-amino acids (α-AAs), and a fully hydroxylated (0001) surface of α-quartz by means of theoretical calculations based on the density functional theory (DFT) under periodic boundary conditions. The influence of microsolvation, represented by a water multilayer, and dispersion forces is analyzed. All the considered molecules strongly adsorb on the hydroxylated surface and prefer to adsorb molecularly. The inclusion of dispersion forces increases the interaction energies by 15-30 kJ/mol, without significant changes in structure and mode of adsorption except for histidine where the interaction is improved through protonation of the α-amine group. When the water multilayer is included a decrease in the surface-adsorbate interaction energies is observed. Also, some α-AAs, glycine and alanine, change their adsorption mode and, now, the more stable structure is the zwitterion. Adsorption as zwitterions is always favored with respect to molecular interaction when dispersion forces are taken into account. Comparing the energies of adsorbed and solvated α-AA zwitterions, it turns out that inclusion of dispersion forces predicts that solvated zwitterions are the lower energy configurations.

  8. Copper ions removal from water using functionalized carbon nanotubes–mullite composite as adsorbent

    SciTech Connect

    Tofighy, Maryam Ahmadzadeh; Mohammadi, Toraj

    2015-08-15

    Highlights: • CNTs–mullite composite was prepared via chemical vapor deposition (CVD) method. • The prepared composite was modified with concentrated nitric acid and chitosan. • The modified CNTs–mullite composites were used as novel adsorbents. • Copper ion removal from water by the prepared adsorbents was performed. • Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. - Abstract: Carbon nanotubes–mullite composite was synthesized by direct growth of carbon nanotubes on mullite particles via chemical vapor deposition method using cyclohexanol and ferrocene as carbon precursor and catalyst, respectively. The carbon nanotubes–mullite composite was oxidized with concentrated nitric acid and functionalized with chitosan and then used as a novel adsorbent for copper ions removal from water. The results demonstrated that modification with concentrated nitric acid and chitosan improves copper ions adsorption capacity of the prepared composite, significantly. Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. The carbon nanotubes growth on mullite particles to form the carbon nanotubes–mullite composite with further modification is an inherently safe approach for many promising environmental applications to avoid some concerns regarding environment, health and safety. It was found that the modified carbon nanotubes–mullite composite can be considered as an excellent adsorbent for copper ions removal from water.

  9. Alternative alkaline conditioning of amidoxime based adsorbent for uranium extraction from seawater

    SciTech Connect

    Das, Sadananda; Liao, Wei -Po; Byers, Maggie Flicker; Tsouris, Costas; Janke, Christopher James; Mayes, Richard T.; Schneider, Eric; Kuo, Li -Jung; Wood, Jordana R.; Gill, Gary A.; Dai, Sheng

    2015-10-18

    Alkaline conditioning of the amidoxime based adsorbents is a significant step in the preparation of the adsorbent for uranium uptake from seawater. The effects of various alkaline conditioning parameters such as the type of alkaline reagent, reaction temperature, and reaction time were investigated with respect to uranium adsorption capacity from simulated seawater (spiked with 8 ppm uranium) and natural seawater (from Sequim Bay, WA). An adsorbent (AF1) was prepared at the Oak Ridge National Laboratory by radiation-induced graft polymerization (RIGP) with acrylonitrile and itaconic acid onto high-surface-area polyethylene fibers. For the AF1 adsorbent, sodium hydroxide emerged as a better reagent for alkaline conditioning over potassium hydroxide, which has typically been used in previous studies, because of higher uranium uptake capacity and lower cost over the other candidate alkaline reagents investigated in this study. Furthermore, the use of sodium hydroxide in place of potassium hydroxide is shown to result in a 21–30% decrease in the cost of uranium recovery.

  10. Nanoscale confinement and interfacial effects on the dynamics and glass transition/crystallinity of thin adsorbed films on silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Madathingal, Rajesh Raman

    The research investigated in this dissertation has focused on understanding the structure-property-function relationships of polymer nanocomposites. The properties of composite systems are dictated by the properties of their components, typically fillers in a polymer matrix. In nanocomposites, the polymer near an interface has significantly different properties compared with the bulk polymer, and the contribution of the adsorbed polymer to composite properties becomes increasingly important as the filler size decreases. Despite many reports of highly favorable properties, the behavior of polymer nanocomposites is not generally predictable, and thus requires a better understanding of the interfacial region. The ability to tailor the filler/matrix interaction and an understanding of the impact of the interface on macroscopic properties are keys in the design of nanocomposite properties. In this original work the surface of silica nanoparticles was tailored by: (a) Changing the number of sites for polymer attachment by varying the surface silanols and, (b) By varying the size/curvature of nanoparticles. The effect of surface tailoring on the dynamic properties after the adsorption of two model polymers, amorphous polymethyl methacrylate (PMMA) and semicrystalline polyethylene oxide (PEO) was observed. The interphase layer of polymers adsorbed to silica surfaces is affected by the surface silanol density as well as the relative size of the polymer compared with the size of the adsorbing substrate. The non-equilibrium adsorption of PMMA onto individual colloidal Stober silica (SiO2) particles, where Rparticle (100nm) > RPMMA (˜6.5nm) was compared with the adsorption onto fumed silica, where Rparticle (7nm) ˜ RPMMA (6.5nm) < Raggregate (˜1000nm), both as a function of silanol density [SiOH] and hydrophobility. In the former case, TEM images showed that the PMMA adsorbed onto individual nanoparticles, so that the number of PMMA chains/bead could be calculated, whereas

  11. 12 CFR 313.95 - Amounts withheld.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... CORPORATE DEBT COLLECTION Administrative Wage Garnishment § 313.95 Amounts withheld. (a) Upon receipt of the... orders with priority, the following shall apply: (1) Unless otherwise provided by federal...

  12. Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

    DOEpatents

    Gaffney, T.R.; Golden, T.C.; Mayorga, S.G.; Brzozowski, J.R.; Taylor, F.W.

    1999-06-29

    A pressure swing adsorption process for absorbing CO[sub 2] from a gaseous mixture containing CO[sub 2] comprises introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100 C and 500 C to adsorb CO[sub 2] to provide a CO[sub 2] laden alumina adsorbent and a CO[sub 2] depleted gaseous mixture and contacting the CO[sub 2] laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO[sub 2] from the CO[sub 2] laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100 C and 600 C, is not degraded by high concentrations of water under process operating conditions. 1 fig.

  13. Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

    DOEpatents

    Gaffney, Thomas Richard; Golden, Timothy Christopher; Mayorga, Steven Gerard; Brzozowski, Jeffrey Richard; Taylor, Fred William

    1999-01-01

    A pressure swing adsorption process for absorbing CO.sub.2 from a gaseous mixture containing CO.sub.2 comprising introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100.degree. C. and 500.degree. C. to adsorb CO.sub.2 to provide a CO.sub.2 laden alumina adsorbent and a CO.sub.2 depleted gaseous mixture and contacting the CO.sub.2 laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO.sub.2 from the CO.sub.2 laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100.degree. C. and 600.degree. C., is not degraded by high concentrations of water under process operating conditions.

  14. Methane Recovery from Gaseous Mixtures Using Carbonaceous Adsorbents

    NASA Astrophysics Data System (ADS)

    Buczek, Bronisław

    2016-06-01

    Methane recovery from gaseous mixtures has both economical and ecological aspect. Methane from different waste gases like mine gases, nitrogenated natural gases and biogases can be treated as local source for production electric and heat energy. Also occurs the problem of atmosphere pollution with methane that shows over 20 times more harmful environmental effect in comparison to carbon dioxide. One of the ways utilisation such gases is enrichment of methane in the PSA technique, which requires appropriate adsorbents. Active carbons and carbon molecular sieve produced by industry and obtained in laboratory scale were examined as adsorbent for methane recuperation. Porous structure of adsorbents was investigated using densimetry measurements and adsorption of argon at 77.5K. On the basis of adsorption data, the Dubinin-Radushkevich equation parameters, micropore volume (Wo) and characteristics of energy adsorption (Eo) as well as area micropores (Smi) and BET area (SBET) were determined. The usability of adsorbents in enrichment of the methane was evaluated in the test, which simulate the basic stages of PSA process: a) adsorbent degassing, b) pressure raise in column by feed gas, c) cocurrent desorption with analysis of out flowing gas. The composition of gas phase was accepted as the criterion of the suitability of adsorbent for methane separation from gaseous mixtures. The relationship between methane recovery from gas mixture and texture parameters of adsorbents was found.

  15. 23 CFR 1335.8 - Grant amounts.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false Grant amounts. 1335.8 Section 1335.8 Highways NATIONAL... § 1335.8 Grant amounts. (a) Start-up grant. A State that qualifies for a start-up grant under § 1335.7(a) of this part shall be eligible to receive $25,000. (b) Initiation grant. A State that qualifies...

  16. Porous materials as high performance adsorbents for CO2 capture, gas separation and purification

    NASA Astrophysics Data System (ADS)

    Wang, Jun

    Global warming resulted from greenhouse gases emission has received a widespread attention. Among the greenhouse gases, CO2 contributes more than 60% to global warming due to its huge emission amount. The flue gas contains about 15% CO2 with N2 as the balance. If CO2 can be separated from flue gas, the benefit is not only reducing the global warming effect, but also producing pure CO2 as a very useful industry raw material. Substantial progress is urgent to be achieved in an industrial process. Moreover, energy crisis is one of the biggest challenges for all countries due to the short life of fossil fuels, such as, petroleum will run out in 50 years and coal will run out in 150 years according to today's speed. Moreover, the severe pollution to the environment caused by burning fossil fuels requires us to explore sustainable, environment-friendly, and facile energy sources. Among several alternative energy sources, natural gas is one of the most promising alternative energy sources due to its huge productivity, abundant feed stock, and ease of generation. In order to realize a substantial adsorption process in industry, synthesis of new adsorbents or modification of existing adsorbent with improved properties has become the most critical issue. This dissertation reports systemic characterization and development of five serials of novel adsorbents with advanced adsorption properties. In chapter 2, nitrogen-doped Hypercross-linking Polymers (HCPs) have been synthesized successfully with non-carcinogenic chloromethyl methyl ether (CME) as the cross-linking agent within a single step. Texture properties, surface morphology, CO2/N2 selectivity, and adsorption heat have been presented and demonstrated properly. A comprehensive discussion on factors that affect the CO2 adsorption and CO2/N 2 separation has also been presented. It was found that high micropore proportion and N-content could effectively enhance CO2 uptake and CO2/N2 separation selectivity. In chapter 3, a

  17. Amino-functionalized adsorbent prepared by means of Cu(II) imprinted method and its selective removal of copper from aqueous solutions.

    PubMed

    Peng, Wei; Xie, Zhenzhen; Cheng, Ge; Shi, Lei; Zhang, Yibo

    2015-08-30

    An amino-functionalized modified metal ion imprinting adsorbent was newly synthesized for the selective extraction and the removal of Cu(II) from aqueous solution. The adsorption capacity of the amino-functionalized ion-imprinted adsorbent was found to be significantly more than the several adsorbents reported in the literatures. The carbon based adsorbent was characterized by SEM, TEM, XPS, Elemental analysis and FTIR respectively. The optimum pH for Cu(II) adsorption was found to be 5. The adsorption equilibrium isotherm could be described by Langmuir model, the Langmuir isotherm has shown an agreement with experimental data, and the maximum adsorption capacity of copper ions for Cu(II) imprinted adsorbent was 33.33mg/g. The selectivity coefficients of the imprinted material for Cu(II)/Cd(II), Cu(II)/Co(II), Cu(II)/Ni(II) and Cu(II)/Zn(II) were 31.8, 90.2, 38.6 and 36.1, respectively. Those were 10.6, 6.22, 7.11 and 39.2 times greater than that of non-imprinted material, respectively. The high adsorption capacity and selectivity coefficient indicated that this amino-functionalized ion-imprinted adsorbent can be used as the selective adsorbent for the removal of copper ions from wastewater. In this work, glucose, tetraethylene pentamine (TEPA) and copper ions as template are combined together with specific mole radio for preparing carbon-based adsorbent by means of hydrothermal synthesis method.

  18. Novel adhesive properties of poly(ethylene-oxide) adsorbed nanolayers

    NASA Astrophysics Data System (ADS)

    Zeng, Wenduo

    Solid-polymer interfaces play crucial roles in the multidisciplinary field of nanotechnology and are the confluence of physics, chemistry, biology, and engineering. There is now growing evidence that polymer chains irreversibly adsorb even onto weakly attractive solid surfaces, forming a nanometer-thick adsorbed polymer layer ("adsorbed polymer nanolayers"). It has also been reported that the adsorbed layers greatly impact on local structures and properties of supported polymer thin films. In this thesis, I aim to clarify adhesive and tribological properties of adsorbed poly(ethylene-oxide) (PEO) nanolayers onto silicon (Si) substrates, which remain unsolved so far. The adsorbed nanolayers were prepared by the established protocol: one has to equilibrate the melt or dense solution against a solid surface; the unadsorbed chains can be then removed by a good solvent, while the adsorbed chains are assumed to maintain the same conformation due to the irreversible freezing through many physical solid-segment contacts. I firstly characterized the formation process and the surface/film structures of the adsorbed nanolayers by using X-ray reflectivity, grazing incidence X-ray diffraction, and atomic force microscopy. Secondly, to compare the surface energy of the adsorbed layers with the bulk, static contact angle measurements with two liquids (water and glycerol) were carried out using a optical contact angle meter equipped with a video camera. Thirdly, I designed and constructed a custom-built adhesion-testing device to quantify the adhesive property. The experimental results provide new insight into the microscopic structure - macroscopic property relationship at the solid-polymer interface.

  19. Removal of microcystin-LR from drinking water using a bamboo-based charcoal adsorbent modified with chitosan.

    PubMed

    Zhang, Hangjun; Zhu, Guoying; Jia, Xiuying; Ding, Ying; Zhang, Mi; Gao, Qing; Hu, Ciming; Xu, Shuying

    2011-01-01

    A new kind of low-cost syntactic adsorbent from bamboo charcoal and chitosan was developed for the removal of microcystin-LR from drinking water. Removal efficiency was higher for the syntactic adsorbent when the amount of bamboo charcoal was increased. The optimum dose ratio of bamboo charcoal to chitosan was 6:4, and the optimum amount was 15 mg/L; equilibrium time was 6 hr. The adsorption isotherm was non-linear and could be simulated by the Freundlich model (R2 = 0.9337). Adsorption efficiency was strongly affected by pH and natural organic matter (NOM). Removal efficiency was 16% higher at pH 3 than at pH 9. Efficiency rate was reduced by 15% with 25 mg/L NOM (UV254 = 0.089 cm(-1)) in drinking water. This study demonstrated that the bamboo charcoal modified with chitosan can effectively remove microcystin-LR from drinking water.

  20. Mysterious Lattice Rotations in Adsorbed Monolayers

    NASA Astrophysics Data System (ADS)

    Diehl, Renee D.

    1997-03-01

    Lattice rotations due to a mismatch in structure have been observed in film growth for many years, probably beginning in the 1930's with the Nishiyama-Wasserman and Kurdjumov-Sachs orientations observed when fcc(111) films grow on bcc(110) surfaces, or vice versa. Early analysis of this problem was carried out with the aid of Moiré patterns and the observation that the preferred lattice orientations are those which maximize the Moiré fringe spacing. Later energy calculations indicated that the structures which were predicted by the the Moiré technique actually do correspond to energy minima. Epitaxial rotation in adsorbed monolayers is a conceptually simpler problem since in principle it involves only two planes of atoms, and it was first observed in 1977 for Ar on a graphite surface(C. G. Shaw, M. D. Chinn, S. C. Fain, Jr. Phys. Rev. Lett. 41 (1978) 955.). This observation came only a few months after a new theory, based on the expected elastic behavior of an overlayer, was developed by A. D. Novaco and J. P. McTague(A. D. Novaco and J. P. McTague, Phys. Rev. Lett. 38 (1977) 1286.), and the agreement with the experimental results was remarkable. It was later shown that a few symmetry principles similar to those used for the film growth studies sometimes can also predict the observed structures. However, the situation for incommensurate layers physisorbed on metal surfaces currently looks bleak. None of the existing theories or models appears to describe the experimental results. New data for physisorbed gases on metal surfaces will be presented, along with some half-baked (and probably wrong) ideas for what might be happening. This work was supported by NSF.

  1. Microfungal alkylation and volatilization of selenium adsorbed by goethite.

    PubMed

    Peitzsch, Mirko; Kremer, Daniel; Kersten, Michael

    2010-01-01

    Selenium adsorbed in the oxyanionic form by Fe-oxides like goethite is considered of benefit for long-term stabilization of (79)Se under near field conditions of radionuclide waste disposal sites. However, microbe-mediated volatilization of the uranium fission product (79)Se has not yet been considered for risk assessment based on the use of the water-solid distribution coefficient K(D). We have performed incubation experiments in a ternary system selenium-microbe-goethite and show that mycobiota including the common black microfungi genera Alternaria alternata are capable of volatilizing the Se even if immobilized by goethite. The microfungi were incubated in a standardized nutrient broth suspension with 10 g L(-1) of the oxide target under defined conditions. Volatile organic selenium (VOSe) species formed in the head space of the culture flasks were sampled and measured directly by a cryotrapping cryofocusing gas chromatographic system coupled with ICP-MS detection (CT-CF-GC-ICP-MS). Alkylated VOSe species were found at the tens to hundreds ng m(-3) levels dominated by dimethyl selenide (DMSe) and dimethyl diselenide (DMDSe). The total amount of DMSe released into the 80-mL headspace volume within the 21 days of incubation was up to 1.12 +/- 0.17 nmol and 0.48 +/- 0.12 nmol for systems without and with goethite amendment, respectively. Alkylation rates of up to 0.1 mumol Se per day and g biomass cannot be neglected as a potential fission product mobilization pathway, unless the inherent radioactivity is proven to prevent any such microbial activity on the long-term. Otherwise it may lead to an onsite accumulation of (79)Se through evapoconcentration in the enclosed underground caverns.

  2. Enhancing Uranium Uptake by Amidoxime Adsorbent in Seawater: An investigation for optimum alkaline conditioning parameters

    SciTech Connect

    Das, S.; Tsouris, Constantinos; Zhang, C.; Kim, J.; Brown, S.; Oyola, Yatsandra; Janke, C.; Mayes, R. T.; Kuo, Li-Jung; Wood, Jordana R.; Gill, Gary A.; Dai, Sheng

    2016-04-20

    A high-surface-area polyethylene-fiber adsorbent (AF160-2) has been developed at the Oak Ridge National Laboratory (ORNL) by radiation-induced graft polymerization of acrylonitrile and itaconic acid. The grafted nitriles were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with potassium hydroxide (KOH) by varying different reaction parameters such as KOH concentration (0.2, 0.44, and 0.6 M), duration (1, 2, and 3 h), and temperature (60, 70, and 80 ºC). Adsorbent screening was then performed with simulated seawater solutions containing sodium chloride and sodium bicarbonate, at concentrations found in seawater, and uranium nitrate at a uranium concentration of ~ 7-8 ppm and pH 8. FTIR and solid state NMR indicated that a fraction of amidoxime groups was hydrolyzed to carboxylate during KOH conditioning. The uranium adsorption capacity in the simulated seawater screening solution gradually increased with conditioning time and temperature for all KOH concentrations. It was also observed that the adsorption capacity increased with an increase in concentration of KOH for all the conditioning times and temperatures. AF160-2 adsorbent samples were also tested with natural seawater using flow-through experiments to determine uranium adsorption capacity with varying KOH conditioning time and temperature. Based on uranium loading capacity values of several AF160-2 samples, it was observed that changing KOH conditioning time from 3 to 1 h at 60, 70, and 80 ºC resulted in increase of the uranium loading capacity in seawater, which did not follow the trend found in laboratory screening with stimulated solutions. Longer KOH conditioning times lead to significantly higher uptake of divalent metal ions, such as calcium and magnesium, which is a result of amidoxime conversion into less selective carboxylate. Scanning electron microscopy showed that long conditioning times may also lead to adsorbent degradation

  3. Influences of Dilute Organic Adsorbates on the Hydration of Low-Surface-Area Silicates.

    PubMed

    Sangodkar, Rahul P; Smith, Benjamin J; Gajan, David; Rossini, Aaron J; Roberts, Lawrence R; Funkhouser, Gary P; Lesage, Anne; Emsley, Lyndon; Chmelka, Bradley F

    2015-07-01

    Competitive adsorption of dilute quantities of certain organic molecules and water at silicate surfaces strongly influence the rates of silicate dissolution, hydration, and crystallization. Here, we determine the molecular-level structures, compositions, and site-specific interactions of adsorbed organic molecules at low absolute bulk concentrations on heterogeneous silicate particle surfaces at early stages of hydration. Specifically, dilute quantities (∼0.1% by weight of solids) of the disaccharide sucrose or industrially important phosphonic acid species slow dramatically the hydration of low-surface-area (∼1 m(2)/g) silicate particles. Here, the physicochemically distinct adsorption interactions of these organic species are established by using dynamic nuclear polarization (DNP) surface-enhanced solid-state NMR techniques. These measurements provide significantly improved signal sensitivity for near-surface species that is crucial for the detection and analysis of dilute adsorbed organic molecules and silicate species on low-surface-area particles, which until now have been infeasible to characterize. DNP-enhanced 2D (29)Si{(1)H}, (13)C{(1)H}, and (31)P{(1)H} heteronuclear correlation and 1D (29)Si{(13)C} rotational-echo double-resonance NMR measurements establish hydrogen-bond-mediated adsorption of sucrose at distinct nonhydrated and hydrated silicate surface sites and electrostatic interactions with surface Ca(2+) cations. By comparison, phosphonic acid molecules are found to adsorb electrostatically at or near cationic calcium surface sites to form Ca(2+)-phosphonate complexes. Although dilute quantities of both types of organic molecules effectively inhibit hydration, they do so by adsorbing in distinct ways that depend on their specific architectures and physicochemical interactions. The results demonstrate the feasibility of using DNP-enhanced NMR techniques to measure and assess dilute adsorbed molecules and their molecular interactions on low

  4. Enhancing uranium uptake by amidoxime adsorbent in seawater: An investigation for optimum alkaline conditioning parameters

    DOE PAGES

    Das, Sadananda; Tsouris, Costas; Zhang, Chenxi; ...

    2015-09-07

    A high-surface-area polyethylene-fiber adsorbent (AF160-2) has been developed at the Oak Ridge National Laboratory by radiation-induced graft polymerization of acrylonitrile and itaconic acid. The grafted nitriles were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with potassium hydroxide (KOH) by varying different reaction parameters such as KOH concentration (0.2, 0.44, and 0.6 M), duration (1, 2, and 3 h), and temperature (60, 70, and 80 °C). Adsorbent screening was then performed with simulated seawater solutions containing sodium chloride and sodium bicarbonate, at concentrations found in seawater, and uranium nitrate at a uranium concentration ofmore » ~7–8 ppm and pH 8. Fourier transform infrared spectroscopy and solid-state NMR analyses indicated that a fraction of amidoxime groups was hydrolyzed to carboxylate during KOH conditioning. The uranium adsorption capacity in the simulated seawater screening solution gradually increased with conditioning time and temperature for all KOH concentrations. It was also observed that the adsorption capacity increased with an increase in concentration of KOH for all the conditioning times and temperatures. AF160-2 adsorbent samples were also tested with natural seawater using flow-through experiments to determine uranium adsorption capacity with varying KOH conditioning time and temperature. Based on uranium loading capacity values of several AF160-2 samples, it was observed that changing KOH conditioning time from 3 to 1 h at 60, 70, and 80 °C resulted in an increase of the uranium loading capacity in seawater, which did not follow the trend found in laboratory screening with stimulated solutions. Longer KOH conditioning times lead to significantly higher uptake of divalent metal ions, such as calcium and magnesium, which is a result of amidoxime conversion into less selective carboxylate. The scanning electron microscopy showed that long

  5. Batch technique to evaluate the efficiency of different natural adsorbents for defluoridation from groundwater

    NASA Astrophysics Data System (ADS)

    Kumar, Pankaj; Saraswat, Chitresh; Mishra, Binaya Kumar; Avtar, Ram; Patel, Hiral; Patel, Asha; Sharma, Tejal; Patel, Roshni

    2016-09-01

    Fluoride pollution (with concentration >1.0 mg/L) in groundwater has become a global threat in the recent past due to the lesser availability of potable groundwater resource. In between several defluoridation techniques discovered so far, the adsorption process proved to be most economic and efficient. This study is an effort to evaluate defluoridation efficiency of powdered rice husk, fine chopped rice husk and sawdust by the batch adsorption process. Optimum defluoridation capacity is achieved by optimizing various parameters, viz. dose of adsorbent, pH, contact time and initial concentration. It was found that all three materials can be employed for the defluoridation technique, but powdered rice husk is the best adsorbent in the midst of all three. Powdered rice husk showed fluoride removal efficiency ranging between 85 and 90 % in the contact period of 7 h only in conditions of all optimized parameter. Following this parameter optimization, adsorption efficiency was also evaluated at natural pH of groundwater to minimize the cost of defluoridation. No significant difference was found between fluoride adsorption at optimized pH (pH = 4) and natural one (pH = 7), which concludes that powdered rice husk can be efficiently used for the defluoridation technique at field scale. The adsorption isotherm using this adsorbent perfectly followed Langmuir isotherms. The value of calculated separation factor also suggests the favourable adsorption of fluoride onto this adsorbent under the conditions used for the experiments. The field application for defluoridation of groundwater using this adsorbent (based on pH of natural groundwater there and seasonal variation of temperature) showed the high success rate.

  6. Enhancing uranium uptake by amidoxime adsorbent in seawater: An investigation for optimum alkaline conditioning parameters

    SciTech Connect

    Das, Sadananda; Tsouris, Costas; Zhang, Chenxi; Brown, Suree; Janke, Christopher James; Mayes, Richard T.; Kuo, Li -Jung; Gill, Gary; Dai, Sheng; Kim, J.; Oyola, Y.; Wood, J. R.

    2015-09-07

    A high-surface-area polyethylene-fiber adsorbent (AF160-2) has been developed at the Oak Ridge National Laboratory by radiation-induced graft polymerization of acrylonitrile and itaconic acid. The grafted nitriles were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with potassium hydroxide (KOH) by varying different reaction parameters such as KOH concentration (0.2, 0.44, and 0.6 M), duration (1, 2, and 3 h), and temperature (60, 70, and 80 °C). Adsorbent screening was then performed with simulated seawater solutions containing sodium chloride and sodium bicarbonate, at concentrations found in seawater, and uranium nitrate at a uranium concentration of ~7–8 ppm and pH 8. Fourier transform infrared spectroscopy and solid-state NMR analyses indicated that a fraction of amidoxime groups was hydrolyzed to carboxylate during KOH conditioning. The uranium adsorption capacity in the simulated seawater screening solution gradually increased with conditioning time and temperature for all KOH concentrations. It was also observed that the adsorption capacity increased with an increase in concentration of KOH for all the conditioning times and temperatures. AF160-2 adsorbent samples were also tested with natural seawater using flow-through experiments to determine uranium adsorption capacity with varying KOH conditioning time and temperature. Based on uranium loading capacity values of several AF160-2 samples, it was observed that changing KOH conditioning time from 3 to 1 h at 60, 70, and 80 °C resulted in an increase of the uranium loading capacity in seawater, which did not follow the trend found in laboratory screening with stimulated solutions. Longer KOH conditioning times lead to significantly higher uptake of divalent metal ions, such as calcium and magnesium, which is a result of amidoxime conversion into less selective carboxylate. The scanning electron microscopy showed that long conditioning

  7. Effects of excluded surface area and adsorbate clustering on surface adsorption of proteins. II. Kinetic models.

    PubMed Central

    Minton, A P

    2001-01-01

    Models for equilibrium surface adsorption of proteins have been recently proposed (Minton, A. P., 2000. Biophys. Chem. 86:239-247) in which negative cooperativity due to area exclusion by adsorbate molecules is compensated to a variable extent by the formation of a heterogeneous population of monolayer surface clusters of adsorbed protein molecules. In the present work this concept is extended to treat the kinetics of protein adsorption. It is postulated that clusters may grow via two distinct kinetic pathways. The first pathway is the diffusion of adsorbed monomer to the edge of a preexisting cluster and subsequent accretion. The second pathway consists of direct deposition of a monomer in solution onto the upper (solution-facing) surface of a preexisting cluster ("piggyback" deposition) and subsequent incorporation into the cluster. Results of calculations of the time course of adsorption, carried out for two different limiting models of cluster structure and energetics, show that in the absence of piggyback deposition, enhancement of the tendency of adsorbate to cluster can reduce, but not eliminate, the negative kinetic cooperativity due to surface area exclusion by adsorbate. Apparently noncooperative (Langmuir-like) and positively cooperative adsorption progress curves, qualitatively similar to those reported in several published experimental studies, require a significant fraction of total adsorption flux through the piggyback deposition pathway. According to the model developed here and in the above-mentioned reference, the formation of surface clusters should be a common concomitant of non-site-specific surface adsorption of proteins, and may provide an important mechanism for assembly of organized "protein machines" in vivo. PMID:11259279

  8. 75 FR 58407 - Medicare Program; Medicare Appeals; Adjustment to the Amount in Controversy Threshold Amounts for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-24

    ... to the Amount in Controversy Threshold Amounts for Calendar Year 2011 AGENCY: Centers for Medicare... July of the preceding year involved and rounded to the nearest multiple of $10. B. Calendar Year 2011... judicial review will rise to $1,300 for the 2011 calendar year. These updated amounts are based on the...

  9. 77 FR 59618 - Medicare Program; Medicare Appeals; Adjustment to the Amount in Controversy Threshold Amounts for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-28

    ... to the Amount in Controversy Threshold Amounts for Calendar Year 2013 AGENCY: Centers for Medicare... for requests for ALJ hearings and judicial review filed on or after January 1, 2013. The calendar year... nearest multiple of $10. B. Calendar Year 2013 The AIC threshold amount for ALJ hearing requests...

  10. Method of coating aluminum substrates with solid adsorbent

    SciTech Connect

    Dunn, S.R.; McKeon, M.J.; Cohen, A.P.; Behan, A.S.

    1992-06-09

    This patent describes a method of coating a surface of an aluminum substrate with a layer of solid adsorbent selected from the group consisting of crystalline molecular sieves, activated alumina, and mixtures thereof. It comprises heating the surface in an oxygen containing atmosphere to a temperature of at least about 200{degrees} C and sufficient to enable bonding of the solid adsorbent to the surface, contacting the heated surface with a slurry comprising the adsorbent and a binder selected from the group consisting of volclay, kaolin, sepiolite, attapulgite, silicates, aluminates, activated alumina, and mixtures thereof in a suspending liquid to form a slurry-coated surface, and removing sufficient liquid to form an adsorbent coating thereon.

  11. Removal of adsorbed gases with CO2 snow

    NASA Astrophysics Data System (ADS)

    Zito, Richard R.

    1991-09-01

    During the outgassing of orbiting astronomical observatories, the condensation of molecular species on optical surfaces can create difficulties for astronomers. The problem is particularly severe in ultraviolet astronomy where the adsorption of only a few atomic layers of some substances can be very damaging. In this paper the removal of adsorbed atomic layers using carbon dioxide snow is discussed. The rate of removal of adsorbed layers of isopropyl alcohol, Freon TF, and deionized distilled water on Teflon substrates was experimentally determined. The removal of fingerprints (containing fatty acids such as stearic acid) from optical surfaces is also demonstrated. The presence and rate of removal of the multilayers was monitored by detecting the molecular dipole field of adsorbed molecular species. For isopropyl alcohol, Freon TF (trichlorotrifluoroethane), and water adsorbed multilayers were removed in under 1.5 seconds. Fingerprint removal was much more difficult and required 20 seconds of spraying with a mixture of carbon dioxide snow flakes and atomized microdroplets of isopropyl alcohol.

  12. Radiation grafted adsorbents for newly emerging environmental applications

    NASA Astrophysics Data System (ADS)

    Mahmoud Nasef, Mohamed; Ting, T. M.; Abbasi, Ali; Layeghi-moghaddam, Alireza; Sara Alinezhad, S.; Hashim, Kamaruddin

    2016-01-01

    Radiation induced grafting (RIG) is acquired to prepare a number of adsorbents for newly emerging environmental applications using a single route involving RIG of glycidymethacrylate (GMA) onto polyethylene-polypropylene (PE-PP) non-woven fabric. The grafted fabric was subjected to one of three functionalization reactions to impart desired ionic characters. This included treatment with (1) N-dimethyl-D-glucamine, (2) triethylamine and (3) triethylamine and alkalisation with KOH. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were used to study the changes in chemical and physical structures of the obtained fibrous adsorbents. The potential applications of the three adsorbents for removal of boron from solutions, capturing CO2 from CO2/N2 mixtures and catalysing transesterification of triacetin/methanol to methyl acetate (biodiesel) were explored. The obtained fibrous adsorbents provide potential alternatives to granular resins for the investigated applications and require further development.

  13. Trace contaminant studies of HSC adsorbent. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Yieh, D. T. N.

    1978-01-01

    The adsorption and desorption of fifteen trace contaminants on HSC (polyethylenimine coated acrylic ester) adsorbent were experimentally investigated with the following two objectives: to test the removal potential and the adsorption reversibility of the selected trace contaminants, and to test the effect a preadsorbed trace contaminant has on the CO2 adsorption capacity. The experimental method for acquiring the adsorption equilibrium data used is based on the volumetric (or displacement) concept of vacuum adsorption. From the experimental results, it was found that the HSC adsorbent has good adsorption potential for contaminants of alcohol compounds, esters, and benzene compounds; whereas, adsorption of ketone compounds, oxidizing and reducing agents are detrimental to the adsorbent. In addition, all liquid contaminants reduce the CO2 capacity of HSC adsorbent.

  14. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    SciTech Connect

    Weinelt, M.; Nilsson, A.; Wassdahl, N.

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  15. Root responses to nitrogen pulse frequency under different nitrogen amounts

    NASA Astrophysics Data System (ADS)

    Yuan, Qing-Ye; Wang, Pu; Liu, Lu; Dong, Bi-Cheng; Yu, Fei-Hai

    2017-04-01

    Responses of morphology and biomass allocation of roots to frequency of nitrogen (N) pulse potentially influence the fitness of plants, but such responses may be determined by root size. We grew 12 plant species of three functional groups (grasses, forbs, and legumes) under two N pulse frequencies (high vs. low supply frequency) and two N amounts (high vs. low supply amount). Compared to low-amount N supply, high-amount N supply stimulated biomass accumulation and root growth by either increasing the thickness and length of roots or decreasing the root mass fraction. Compared to low-frequency N supply, high-frequency N supply improved biomass accumulation and root growth in forbs or grasses, but not in legumes. Furthermore, the magnitude of the response to N frequency was significantly negatively correlated with root size at the species scale, but this was only true when the N amount was high. We conclude that root responses to N frequency are related to plant functional types, and non-legume species is more sensitive to N frequency than legume species. Our results also suggest that root size is a determinant of root responses to N frequency when N supply amount is high.

  16. Residence time determination for adsorbent beds of different configurations

    SciTech Connect

    Otermat, J.E.; Wikoff, W.O.; Kovach, J.L.

    1995-02-01

    The residence time calculations of ASME AG-1 Code, Section FC, currently specify a screen surface area method, that is technically incorrect. Test data has been obtained on Type II adsorber trays of different configurations to establish residence time in the adsorber trays. These data indicate that the air volume/carbon volume ratio or the average screen area are more appropriate for the calculation of the residence time calculation than the currently used, smallest screen area basis.

  17. Structure of water adsorbed on a single graphene sheet

    NASA Astrophysics Data System (ADS)

    Gordillo, M. C.; Martí, J.

    2008-08-01

    We present the result of molecular-dynamics simulations of water adsorbed on top of a single graphene layer at temperatures between 25 and 50°C . The analysis of the energy per particle and the density profiles indicate that the behavior of the adsorbed liquid is similar to the case of multiple graphene layers (graphite) with the only difference being the values of configurational energy. Other structural properties, such as stability ranges, hydrogen bond distributions, and molecular orientations are also presented.

  18. HYDROGEN GENERATION FROM PLASMATRON REFORMERS: A PROMISING TECHNOLOGY FOR NOX ADSORBER REGENERATION AND OTHER AUTOMOTIVE APPLICATIONS

    SciTech Connect

    Bromberg, L.; Crane, S; Rabinovich, A.; Kong, Y; Cohn, D; Heywood, J; Alexeev, N.; Samokhin, A.

    2003-08-24

    Plasmatron reformers are being developed at MIT and ArvinMeritor [1]. In these reformers a special low power electrical discharge is used to promote partial oxidation conversion of hydrocarbon fuels into hydrogen and CO. The partial oxidation reaction of this very fuel rich mixture is difficult to initiate. The plasmatron provides continuous enhanced volume initiation. To minimize electrode erosion and electrical power requirements, a low current, high voltage discharge with wide area electrodes is used. The reformers operate at or slightly above atmospheric pressure. Plasmatron reformers provide the advantages of rapid startup and transient response; efficient conversion of the fuel to hydrogen rich gas; compact size; relaxation or elimination of reformer catalyst requirements; and capability to process difficult to reform fuels, such as diesel and bio-oils. These advantages facilitate use of onboard hydrogen-generation technology for diesel exhaust after-treatment. Plasma-enhanced reformer technology can provide substantial conversion even without the use of a catalyst. Recent progress includes a substantial decrease in electrical power consumption (to about 200 W), increased flow rate (above 1 g/s of diesel fuel corresponding to approximately 40 kW of chemical energy), soot suppression and improvements in other operational features.. Plasmatron reformer technology has been evaluated for regeneration of NOx adsorber after-treatment systems. At ArvinMeritor tests were performed on a dual-leg NOx adsorber system using a Cummins 8.3L diesel engine both in a test cell and on a vehicle. A NOx adsorber system was tested using the plasmatron reformer as a regenerator and without the reformer i.e., with straight diesel fuel based regeneration as the baseline case. The plasmatron reformer was shown to improve NOx regeneration significantly compared to the baseline diesel case. The net result of these initial tests was a significant decrease in fuel penalty, roughly 50% at

  19. Efforts to Consolidate Chalcogels with Adsorbed Iodine

    SciTech Connect

    Riley, Brian J.; Pierce, David A.; Chun, Jaehun

    2013-08-28

    This document discusses ongoing work with non-oxide aerogels, called chalcogels, that are under development at the Pacific Northwest National Laboratory as sorbents for gaseous iodine. Work was conducted in fiscal year 2012 to demonstrate the feasibility of converting Sn2S3 chalcogel without iodine into a glass. This current document summarizes the work conducted in fiscal year 2013 to assess the consolidation potential of non-oxide aerogels with adsorbed iodine. The Sn2S3 and Sb13.5Sn5S20 chalcogels were selected for study. The first step in the process for these experiments was to load them with iodine (I2). The I2 uptake was ~68 mass% for Sn2S3 and ~50 mass% for Sb13.5Sn5S20 chalcogels. X-ray diffraction (XRD) of both sets of sorbents showed that metal-iodide complexes were formed during adsorption, i.e., SnI4 for Sn2S3 and SbI3 for Sb13.5Sn5S20. Additionally, metal-sulfide-iodide complexes were formed, i.e., SnSI for Sn2S3 and SbSI for Sb13.5Sn5S20. No XRD evidence for unreacted iodine was found in any of these samples. Once the chalcogels had reached maximum adsorption, the consolidation potential was assessed. Here, the sorbents were heated for consolidation in vacuum-sealed quartz vessels. The Sb13.5Sn5S20 chalcogel was heated both (1) in a glassy carbon crucible within a fused quartz tube and (2) in a single-containment fused quartz tube. The Sn2S3 chalcogel was only heated in a single-containment fused quartz tube. In both cases with the single-containment fused quartz experiments, the material consolidated nicely. However, in both cases, there were small fractions of metal iodides not incorporated into the final product as well as fused quartz particles within the melt due to the sample attacking the quartz wall during the heat treatment. The Sb13.5Sn5S20 did not appear to attack the glassy carbon crucible so, for future experiments, it would be ideal to apply a coating, such as pyrolytic graphite, to the inner walls of the fused quartz vessel to prevent

  20. Treatment with activated carbon and other adsorbents as an effective method for the removal of volatile compounds in agricultural distillates.

    PubMed

    Balcerek, Maria; Pielech-Przybylska, Katarzyna; Patelski, Piotr; Dziekońska-Kubczak, Urszula; Jusel, Tomaš

    2017-02-08

    This study investigates the effect of treatment with activated carbon and other adsorbents on the chemical composition and organoleptics of a barley malt-based agricultural distillate. Contact with activated carbon is one of the methods by which the quality of raw distillates and spirit beverages can be improved. Samples placed in contact with 1 g activated carbon (SpiritFerm) per 100 ml distillate with ethanol content of 50% v/v for 1 h showed the largest reductions in the concentrations of most volatile compounds (aldehydes, alcohols, esters). Increasing the dose of adsorbent to over 1 g 100 ml(-1) did not improve the purity of the agricultural distillate significantly. Of the tested compounds, acetaldehyde and methanol showed the lowest adsorption on activated carbon. The lowest concentrations of these congeners (expressed in mg l(-1) alcohol 100% v/v) were measured in solutions with ethanol contents of 70-80% v/v, while solutions with an alcoholic strength by volume of 40% did not show statistically significant decreases in these compounds in relation the control sample. The reductions in volatile compounds were compared with those for other adsorbents based on silica or activated carbon and silica. An interesting alternative to activated carbon was found to be an adsorbent prepared from activated carbon and silica (Spiricol). Treatment with this adsorbent produced distillate with the lowest concentrations of acetaldehyde and isovaleraldehyde, and led to the greatest improvement in its organoleptics.

  1. Study for Reduction of Outgassing Property of Adsorbed Water Gas for Improved Surface Finished Titanium Material

    NASA Astrophysics Data System (ADS)

    Takeda, Masatoshi; Kurisu, Hiroki; Uchida, Takashi; Yamamoto, Setsuo; Ishizawa, Katsunobu; Nomura, Takeru; Eda, Takahiro; Murashige, Nobuyuki

    This paper addresses the development of the surface finishing for a titanium material and the study for the reduction of outgassing property of adsorbed water (H2O) molecules. Developed surface finishing is composed of the buffing for the reduction of the surface roughness and improved chemical polishing for the thick surface oxide layer compared with the chemical polishing so far. The surface roughness of the surface finished titanium material is reduced 35% and the thickness of the surface oxide layer increases by 30%. The total amount of thermal desorbed H2O gas for the new surface finished titanium is reduced 30%. It is considered that the origin for the decrease of the amount of desorption H2O gas is the reduction of the adsorption sites due to the decrease of the surface roughness and the reduction of adsorption energy of H2O gas due to the strong surface oxidation for a titanium material.

  2. The leucine rich amelogenin protein (LRAP) adsorbs as monomers or dimers onto surfaces

    SciTech Connect

    Tarasevich, Barbara J.; Lea, Alan S.; Shaw, Wendy J.

    2010-03-15

    Amelogenin and amelogenin splice variants are believed to be involved in controlling the formation of the highly anisotropic and ordered hydroxyapatite crystallites that form enamel. The adsorption behavior of amelogenin proteins onto substrates is very important because protein-surface interactions are critical to it’s function. We have studied the adsorption of LRAP, a splice variant of amelogenin which may also contribute to enamel function, onto model self-assembled monolayers on gold containing of COOH, CH3, and NH2 end groups. Dynamic light scattering (DLS) experiments indicated that LRAP in phosphate buffered saline (PBS) and solutions at saturation with calcium phosphate contained aggregates of nanospheres. Null ellipsometry and atomic force microscopy (AFM) were used to study protein adsorption amounts and structures. Relatively high amounts of adsorption occurred onto the CH3 and NH2 surfaces from both calcium phosphate and PBS solutions. Adsorption was also promoted onto COOH surfaces when calcium was present in the solutions suggesting an interaction that involves calcium bridging with the negatively charged C-terminus. The ellipsometry and AFM studies suggested that the protein adsorbed onto all surfaces as LRAP monomers. We propose that the monomers adsorb onto the surfaces by disassembling or “shedding” from the nanospheres that are present in solution. This work reveals the importance of small subnanosphere-sized structures of LRAP at interfaces, structures that may be important in the biomineralization of tooth enamel.

  3. Rod-like cyanophenyl probe molecules nanoconfined to oxide particles: Density of adsorbed surface species

    NASA Astrophysics Data System (ADS)

    Frunza, Stefan; Frunza, Ligia; Ganea, Constantin Paul; Zgura, Irina; Brás, Ana Rita; Schönhals, Andreas

    2016-02-01

    Surface layers have already been observed by broadband dielectric spectroscopy for composite systems formed by adsorption of rod-like cyanophenyl derivates as probe molecules on the surface of oxide particles. In this work, features of the surface layer are reported; samples with different amounts of the probe molecules adsorbed onto oxide (nano) particles were prepared in order to study their interactions with the surface. Thermogravimetric analysis (TGA) was applied to analyze the amount of loaded probe molecules. The density of the surface species ns was introduced and its values were estimated from quantitative Fourier transform infrared spectroscopy (FTIR) coupled with TGA. This parameter allows discriminating the composites into several groups assuming a similar interaction of the probe molecules with the hosts of a given group. An influence factor H is further proposed as the ratio of the number of molecules in the surface layer showing a glassy dynamics and the number of molecules adsorbed tightly on the surface of the support: It was found for aerosil composites and used for calculating the maximum filling degree of partially filled silica MCM-41 composites showing only one dielectric process characteristic for glass-forming liquids and a bulk behavior for higher filling degrees.

  4. 33 CFR 133.7 - Requests: Amount.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; STATE ACCESS § 133.7... amount anticipated for immediate removal action for a single oil pollution incident, but, in any event... quantity and composition of the oil, weather conditions and customary costs of similar services in...

  5. 40 CFR 35.9050 - Assistance amount.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Assistance amount. 35.9050 Section 35.9050 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE STATE AND LOCAL ASSISTANCE Financial Assistance for the National Estuary Program § 35.9050...

  6. 40 CFR 35.9050 - Assistance amount.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Assistance amount. 35.9050 Section 35.9050 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE STATE AND LOCAL ASSISTANCE Financial Assistance for the National Estuary Program § 35.9050...

  7. 40 CFR 35.9050 - Assistance amount.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Assistance amount. 35.9050 Section 35.9050 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE STATE AND LOCAL ASSISTANCE Financial Assistance for the National Estuary Program § 35.9050...

  8. 40 CFR 35.9050 - Assistance amount.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 1 2012-07-01 2012-07-01 false Assistance amount. 35.9050 Section 35.9050 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE STATE AND LOCAL ASSISTANCE Financial Assistance for the National Estuary Program § 35.9050...

  9. 7 CFR 1421.304 - Payment amount.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2012 Crop of Wheat, Barley, Oats, and Triticale § 1421.304 Payment amount. (a) The grazing payment rate... payment rate in effect for the predominant class of wheat in the county where the farm is located as of... three (3) similar farms. For triticale, the payment yield shall be the yield for wheat from three...

  10. 7 CFR 1421.304 - Payment amount.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012 Crop of Wheat, Barley, Oats, and Triticale § 1421.304 Payment amount. (a) The grazing payment rate... payment rate in effect for the predominant class of wheat in the county where the farm is located as of... three (3) similar farms. For triticale, the payment yield shall be the yield for wheat from three...

  11. 7 CFR 1421.304 - Payment amount.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2012 Crop of Wheat, Barley, Oats, and Triticale § 1421.304 Payment amount. (a) The grazing payment rate... payment rate in effect for the predominant class of wheat in the county where the farm is located as of... three (3) similar farms. For triticale, the payment yield shall be the yield for wheat from three...

  12. 7 CFR 1421.304 - Payment amount.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 2012 Crop of Wheat, Barley, Oats, and Triticale § 1421.304 Payment amount. (a) The grazing payment rate... payment rate in effect for the predominant class of wheat in the county where the farm is located as of... three (3) similar farms. For triticale, the payment yield shall be the yield for wheat from three...

  13. 14 CFR 1300.13 - Guarantee amount.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Guarantee amount. 1300.13 Section 1300.13 Aeronautics and Space AIR TRANSPORTATION SYSTEM STABILIZATION OFFICE OF MANAGEMENT AND BUDGET AVIATION DISASTER RELIEF-AIR CARRIER GUARANTEE LOAN PROGRAM Minimum Requirements and Application Procedures §...

  14. 33 CFR 135.203 - Amount required.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OFFSHORE OIL POLLUTION COMPENSATION FUND Financial Responsibility for Offshore Facilities § 135.203 Amount required. (a) Each facility that is used for drilling for, producing, or processing oil, or which has the capacity to transport,...

  15. 33 CFR 135.203 - Amount required.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OFFSHORE OIL POLLUTION COMPENSATION FUND Financial Responsibility for Offshore Facilities § 135.203 Amount required. (a) Each facility that is used for drilling for, producing, or processing oil, or which has the capacity to transport,...

  16. 33 CFR 135.203 - Amount required.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OFFSHORE OIL POLLUTION COMPENSATION FUND Financial Responsibility for Offshore Facilities § 135.203 Amount required. (a) Each facility that is used for drilling for, producing, or processing oil, or which has the capacity to transport,...

  17. 21 CFR 1309.11 - Fee amounts.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., IMPORTERS AND EXPORTERS OF LIST I CHEMICALS Fees for Registration and Reregistration § 1309.11 Fee amounts..., or export a List I chemical, the applicant shall pay an annual fee of $1,147. Effective Date Note: At 77 FR 15250, Mar. 15, 2012, § 1309.11 was revised, effective April 16, 2012. For the convenience...

  18. Utility of adsorbents in the purification of drinking water: a review of characterization, efficiency and safety evaluation of various adsorbents.

    PubMed

    Dubey, Shashi Prabha; Gopal, Krishna; Bersillon, J L

    2009-05-01

    Clean drinking water is one of the implicit requisites fora healthy human population. However the growing industrialization and extensive use of chemicals for various concerns, has increased the burden of unwanted pollutants in the drinking water of developing countries like India. The entry of potentially hazardous substances into the biota has been magnifying day by day. In the absence of a possible stoppage of these, otherwise, useful chemicals, the only way to maintain safer water bodies is to develop efficient purifying technologies. One such immensely beneficial procedure that has been in use is that of purification of water using 'adsorbents'. Indigenous minerals and natural plants products have potential for removing many pollutants viz. fluoride, arsenic, nitrate, heavy metals, pesticides as well as trihalomethanes. Adsorbents which are derived from carbon, alumina, zeolite, clay minerals, iron ores, industrial by products, and natural products viz. parts of the plants, herbs and algal biomass offer promising potential of removal. In the recent years attention has been paid to develop process involving screening/pretreatment/activation/impregnation using alkalies, acids, alum, lime, manganese dioxide, ferric chloride and other chemicals which are found to enhance their adsorbing efficiency. Chemical characterization of these adsorbents recapitulates the mechanism of the process. It is imperative to observe that capacities of the adsorbents may vary depending on the characteristics, chemical modifications and concentration of the individual adsorbent. Removal kinetics is found to be based on the experimental conditions viz. pH, concentration of the adsorbate, quantity of the adsorbent and temperature. It is suggested that isotherm model is suitable tool to assess the adsorption capacities in batch and column modes. Safety evaluation and risk assessment of the process/products may be useful to provide guidelines for its sustainable disposal.

  19. Unusual Morphologies of Poly(vinyl alcohol) Thin Films Adsorbed on Poly(dimethylsiloxane) Substrates.

    PubMed

    Karki, Akchheta; Nguyen, Lien; Sharma, Bhanushee; Yan, Yan; Chen, Wei

    2016-04-05

    Adsorption of poly(vinyl alcohol) (PVOH), 99% and 88% hydrolyzed poly(vinyl acetate), to poly(dimethylsiloxane) (PDMS) substrates was studied. The substrates were prepared by covalently attaching linear PDMS polymers of 2, 9, 17, 49, and 116 kDa onto silicon wafers. As the PDMS molecular weight/thickness increases, the adsorbed PVOH thin films progressively transition from continuous to discontinuous morphologies, including honeycomb and fractal/droplet. The structures are the result of thin film dewetting that occurs upon exposure to air. The PVOH film thickness does not vary significantly on these PDMS substrates, implicating the PDMS thickness as the cause for the morphology differences. The adsorbed PVOH thin films are less stable and have a stronger tendency to dewet on thicker, more liquid-like PDMS layers. When PVOH(99%) and PVOH(88%) thin films are compared, fractal and droplet morphologies are observed on high molecular weight PDMS substrates, respectively. The formation of the unique fractal features in the PVOH(99%) thin films as well as other crystalline and semicrystalline thin films is most likely driven by crystallization during the dehydration process in a diffusion-limited aggregation fashion. The only significant enhancement in hydrophilicity via PVOH adsorption was obtained on PDMS(2k), which is completely covered with a PVOH thin film. To mimic the lower receding contact angle and less liquid-like character of the PDMS(2k) substrate, light plasma treatment of the higher molecular weight PDMS substrates was carried out. On the treated PDMS substrates, the adsorbed PVOH thin films are in the more continuous honeycomb morphology, giving rise to significantly enhanced wettability. Furthermore, hydrophobic recovery of the hydrophilized PDMS substrates was not observed during a 1 week period. Thus, light plasma oxidation and subsequent PVOH adsorption can be utilized as a means to effectively hydrophilize conventional PDMS substrates. This study

  20. Fabricating electrospun cellulose nanofibre adsorbents for ion-exchange chromatography.

    PubMed

    Dods, Stewart R; Hardick, Oliver; Stevens, Bob; Bracewell, Daniel G

    2015-01-09

    Protein separation is an integral step in biopharmaceutical manufacture with diffusion-limited packed bed chromatography remaining the default choice for industry. Rapid bind-elute separation using convective mass transfer media offers advantages in productivity by operating at high flowrates. Electrospun nanofibre adsorbents are a non-woven fibre matrix of high surface area and porosity previously investigated as a bioseparation medium. The effects of compression and bed layers, and subsequent heat treatment after electrospinning cellulose acetate nanofibres were investigated using diethylaminoethyl (DEAE) or carboxylate (COO) functionalisations. Transbed pressures were measured and compared by compression load, COO adsorbents were 30%, 70% and 90% higher than DEAE for compressions 1, 5 and 10MPa, respectively, which was attributed to the swelling effect of hydrophilic COO groups. Dynamic binding capacities (DBCs) at 10% breakthrough were measured between 2000 and 12,000CV/h (2s and 0.3s residence times) under normal binding conditions, and DBCs increased with reactant concentration from 4 to 12mgBSA/mL for DEAE and from 10 to 21mglysozyme/mL for COO adsorbents. Comparing capacities of compression loads applied after electrospinning showed that the lowest load tested, 1MPa, yielded the highest DBCs for DEAE and COO adsorbents at 20mgBSA/mL and 27mglysozyme/mL, respectively. At 1MPa, DBCs were the highest for the lowest flowrate tested but stabilised for flowrates above 2000CV/h. For compression loads of 5MPa and 10MPa, adsorbents recorded lower DBCs than 1MPa as a result of nanofibre packing and reduced surface area. Increasing the number of bed layers from 4 to 12 showed decreasing DBCs for both adsorbents. Tensile strengths were recorded to indicate the mechanical robustness of the adsorbent and be related to packing the nanofibre adsorbents in large scale configurations such as pleated cartridges. Compared with an uncompressed adsorbent, compressions of 1, 5

  1. Fabricating electrospun cellulose nanofibre adsorbents for ion-exchange chromatography

    PubMed Central

    Dods, Stewart R.; Hardick, Oliver; Stevens, Bob; Bracewell, Daniel G.

    2015-01-01

    Protein separation is an integral step in biopharmaceutical manufacture with diffusion-limited packed bed chromatography remaining the default choice for industry. Rapid bind-elute separation using convective mass transfer media offers advantages in productivity by operating at high flowrates. Electrospun nanofibre adsorbents are a non-woven fibre matrix of high surface area and porosity previously investigated as a bioseparation medium. The effects of compression and bed layers, and subsequent heat treatment after electrospinning cellulose acetate nanofibres were investigated using diethylaminoethyl (DEAE) or carboxylate (COO) functionalisations. Transbed pressures were measured and compared by compression load, COO adsorbents were 30%, 70% and 90% higher than DEAE for compressions 1, 5 and 10 MPa, respectively, which was attributed to the swelling effect of hydrophilic COO groups. Dynamic binding capacities (DBCs) at 10% breakthrough were measured between 2000 and 12,000 CV/h (2 s and 0.3 s residence times) under normal binding conditions, and DBCs increased with reactant concentration from 4 to 12 mg BSA/mL for DEAE and from 10 to 21 mg lysozyme/mL for COO adsorbents. Comparing capacities of compression loads applied after electrospinning showed that the lowest load tested, 1 MPa, yielded the highest DBCs for DEAE and COO adsorbents at 20 mg BSA/mL and 27 mg lysozyme/mL, respectively. At 1 MPa, DBCs were the highest for the lowest flowrate tested but stabilised for flowrates above 2000 CV/h. For compression loads of 5 MPa and 10 MPa, adsorbents recorded lower DBCs than 1 MPa as a result of nanofibre packing and reduced surface area. Increasing the number of bed layers from 4 to 12 showed decreasing DBCs for both adsorbents. Tensile strengths were recorded to indicate the mechanical robustness of the adsorbent and be related to packing the nanofibre adsorbents in large scale configurations such as pleated cartridges. Compared with an

  2. Adherence of platelets to in situ albumin-binding surfaces under flow conditions: role of surface-adsorbed albumin.

    PubMed

    Guha Thakurta, Sanjukta; Miller, Robert; Subramanian, Anuradha

    2012-08-01

    Surfaces that preferentially bind human serum albumin (HSA) were generated by grafting albumin-binding linear peptide (LP1) onto silicon surfaces. The research aim was to evaluate the adsorption pattern of proteins and the adhesion of platelets from platelet-poor plasma and platelet-rich plasma, respectively, by albumin-binding surfaces under physiological shear rate (96 and 319 s(-1)) conditions. Bound proteins were quantified using enzyme-linked immunosorbent assays (ELISAs) and two-dimensional gel electrophoresis. A ratio of ∼1000:100:1 of adsorbed HSA, human immunoglobulin (HIgG) and human fibrinogen (HFib) was noted, respectively, on LP1-functionalized surfaces, and a ratio of ∼5:2:1 of the same was noted on control surfaces, as confirmed by ELISAs. The surface-adsorbed von Willebrand factor was undetectable by sensitive ELISAs. The amount of adhered platelets correlated with the ratio of adsorbed HSA/HFib. Platelet morphology was more rounded on LP1-functionalized surfaces when compared to control surfaces. The platelet adhesion response on albumin-binding surfaces can be explained by the reduction in the co-adsorption of other plasma proteins in a surface environment where there is an excess of albumin molecules, coupled with restrictions in the conformational transitions of other surface-adsorbed proteins into hemostatically active forms.

  3. Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization from Chlorinated Polypropylene and Polyethylene Trunk Fibers

    DOE PAGES

    Brown, Suree; Chatterjee, Sabornie; Li, Meijun; ...

    2015-12-10

    Seawater contains a large amount of uranium (~4.5 billion tons) which can serve as a limitless supply of an energy source. However, in order to make the recovery of uranium from seawater economically feasible, lower manufacturing and deployment costs are required, and thus, solid adsorbents must have high uranium uptake, reusability, and high selectivity toward uranium. In this study, atom-transfer radical polymerization (ATRP), without the radiation-induced graft polymerization (RIGP), was used for grafting acrylonitrile (AN) and tert-butyl acrylate (tBA) from a new class of trunk fibers, forming adsorbents in a readily deployable form. The new class of trunk fibers wasmore » prepared by the chlorination of PP round fiber, hollow-gear-shaped PP fiber, and hollow-gear-shaped PE fiber. During ATRP, degrees of grafting (d.g.) varied according to the structure of active chlorine sites on trunk fibers and ATRP conditions, and the d.g. as high as 2570% was obtained. Resulting adsorbent fibers were evaluated in U-spiked simulated seawater and the maximum adsorption capacity of 146.6 g U/kg, much higher than that of a standard adsorbent JAEA fiber (75.1 g/kg), was obtained. This new type of trunk fibers can be used for grafting a variety of uranium-interacting ligands, including designed ligands that are highly selective toward uranium.« less

  4. Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization from Chlorinated Polypropylene and Polyethylene Trunk Fibers

    SciTech Connect

    Brown, Suree; Chatterjee, Sabornie; Li, Meijun; Yue, Yanfeng; Tsouris, Costas; Janke, Christopher J.; Saito, Tomonori; Dai, Sheng

    2015-12-10

    Seawater contains a large amount of uranium (~4.5 billion tons) which can serve as a limitless supply of an energy source. However, in order to make the recovery of uranium from seawater economically feasible, lower manufacturing and deployment costs are required, and thus, solid adsorbents must have high uranium uptake, reusability, and high selectivity toward uranium. In this study, atom-transfer radical polymerization (ATRP), without the radiation-induced graft polymerization (RIGP), was used for grafting acrylonitrile (AN) and tert-butyl acrylate (tBA) from a new class of trunk fibers, forming adsorbents in a readily deployable form. The new class of trunk fibers was prepared by the chlorination of PP round fiber, hollow-gear-shaped PP fiber, and hollow-gear-shaped PE fiber. During ATRP, degrees of grafting (d.g.) varied according to the structure of active chlorine sites on trunk fibers and ATRP conditions, and the d.g. as high as 2570% was obtained. Resulting adsorbent fibers were evaluated in U-spiked simulated seawater and the maximum adsorption capacity of 146.6 g U/kg, much higher than that of a standard adsorbent JAEA fiber (75.1 g/kg), was obtained. This new type of trunk fibers can be used for grafting a variety of uranium-interacting ligands, including designed ligands that are highly selective toward uranium.

  5. Expanded graphite loaded with lanthanum oxide used as a novel adsorbent for phosphate removal from water: performance and mechanism study.

    PubMed

    Zhang, Ling; Gao, Yan; Li, Mengxue; Liu, Jianyong

    2015-01-01

    A novel adsorbent of expanded graphite (EG) loaded with lanthanum oxide (EG-LaO) was prepared for phosphate removal from water and characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. The effects of impregnation time, La3+ concentration, activation time, and activation temperature on the phosphate removal performance of the adsorbent were studied for optimization of preparation conditions. Isothermal adsorption studies suggested that the Langmuir model fits the experimental data well. Adsorption kinetics investigation showed that the pseudo-second-order model fits the experimental data quite well, indicating that the adsorption process is mainly a process of chemical adsorption, and chloride ions compete to react with the active sites of the adsorbent but do not prevent phosphate from adsorbing onto EG-LaO. The adsorption mechanism studies were performed by a pH dependence study of the adsorption amount. The results demonstrated that the probable mechanisms of phosphate adsorption on EG-LaO were electrostatic and Lewis acid-base interactions in addition to ion exchange.

  6. Elution by Le Chatelier's principle for maximum recyclability of adsorbents: applied to polyacrylamidoxime adsorbents for extraction of uranium from seawater.

    PubMed

    Oyola, Yatsandra; Vukovic, Sinisa; Dai, Sheng

    2016-05-28

    Amidoxime-based polymer adsorbents have attracted interest within the last decade due to their high adsorption capacities for uranium and other rare earth metals from seawater. The ocean contains an approximated 4-5 billion tons of uranium and even though amidoxime-based adsorbents have demonstrated the highest uranium adsorption capacities to date, they are still economically impractical because of their limited recyclability. Typically, the adsorbed metals are eluted with a dilute acid solution that not only damages the amidoxime groups (metal adsorption sites), but is also not strong enough to remove the strongly bound vanadium, which decreases the adsorption capacity with each cycle. We resolved this challenge by incorporating Le Chatelier's principle to recycle adsorbents indefinitely. We used a solution with a high concentration of amidoxime-like chelating agents, such as hydroxylamine, to desorb nearly a 100% of adsorbed metals, including vanadium, without damaging the metal adsorption sites and preserving the high adsorption capacity. The method takes advantage of knowing the binding mode between the amidoxime ligand and the metal and mimics it with chelating agents that then in a Le Chatelier's manner removes metals by shifting to a new chemical equilibrium. For this reason the method is applicable to any ligand-metal adsorbent and it will make an impact on other extraction technologies.

  7. Assessment of fibronectin conformation adsorbed to polytetrafluoroethylene surfaces from serum protein mixtures and correlation to support of cell attachment in culture.

    PubMed

    Grainger, David W; Pavon-Djavid, Graciella; Migonney, Veronique; Josefowicz, Marcel

    2003-01-01

    Surfaces of polytetrafluoroethylene (PTFE) were exposed to buffered aqueous solutions containing radio-labeled human fibronectin ([125I]Fn), Fn/bovine serum albumin (BSA) binary mixtures of various ratios or whole human plasma dilutions for 1 h. Total adsorbed Fn and albumin adsorption following rinsing was quantified on this surface. 125I-labeled monoclonal antibodies against either the tenth type-III Fn repeat unit (containing the cell-binding RGDS integrin recognition motif) or the Fn amino-terminal domain were used to probe the accessibility of each of these respective Fn regions post-adsorption. Human umbilical vein endothelial cells (HUVECs) were cultured on PTFE surfaces pre-exposed to each of these protein adsorption conditions and compared to identical conditions on tissue culture polystyrene (TCPS). Fn adsorption to PTFE is dependent upon the concentration of albumin co-adsorbing from solution: albumin out-competes Fn for PTFE surface sites even at non-physiological Fn/HSA ratios 10-100-fold biased in Fn. Antibodies against Fn do not readily recognize Fn adsorbed on PTFE as the HSA co-adsorption concentration in either binary mixtures or in plasma increases, indicating albumin masking of adsorbed Fn. At Fn/HSA ratios rich in Fn (1:1, 1:100), albumin co-adsorption actually improves anti-Fn antibody recognition of adsorbed Fn. HUVEC attachment efficiency to PTFE after protein adsorption correlates with amounts of Fn adsorbed and levels of anti-Fn antibody recognition of Fn on PTFE, linking cell attachment to integrin recognition of both adsorbed Fn density and Fn adsorbed conformation on PTFE surfaces.

  8. Extracting Uranium from Seawater: Promising AF Series Adsorbents

    SciTech Connect

    Das, S.; Oyola, Y.; Mayes, Richard T.; Janke, Chris J.; Kuo, L. -J.; Gill, G.; Wood, J. R.; Dai, S.

    2016-04-20

    A new family of high-surface-area polyethylene fiber adsorbents named the AF series was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series adsorbents were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/comonomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154-354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44 M KOH at 80 °C followed by screening at ORNL with sodium-based synthetic aqueous solution, spiked with 8 ppm uranium. The uranium adsorption capacity in simulated seawater screening ranged from 170 to 200 g-U/kg-ads irrespective of %DOG. A monomer/comonomer molar ratio in the range of 7.57-10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at Pacific Northwest National Laboratory (PNNL) using flow-through column experiments to determine uranium loading capacity with varying KOH conditioning times at 80 °C. The highest adsorption capacity of AF1 measured after 56 days of marine testing was demonstrated as 3.9 g-U/kg-adsorbent and 3.2 g-U/kg-adsorbent for 1 and 3 h of KOH conditioning at 80 °C, respectively. Based on capacity values of several AF1 samples, it was observed that changing KOH conditioning from 1 to 3 h at 80 °C resulted in a 22-27% decrease in uranium adsorption capacity in seawater.

  9. Removal of arsenic from groundwater by granular titanium dioxide adsorbent.

    PubMed

    Bang, Sunbaek; Patel, Manish; Lippincott, Lee; Meng, Xiaoguang

    2005-07-01

    A novel granular titanium dioxide (TiO2) was evaluated for the removal of arsenic from groundwater. Laboratory experiments were carried out to investigate the adsorption capacity of the adsorbent and the effect of anions on arsenic removal. Batch experimental results showed that more arsenate [As(V)] was adsorbed on TiO2 than arsenite [As(III)] in US groundwater at pH 7.0. The adsorption capacities for As(V) and As(III) were 41.4 and 32.4 mgg(-1) TiO2, respectively. However, the adsorbent had a similar adsorption capacity for As(V) and As(III) (approximately 40 mgg(-1)) when simulated Bangladesh groundwater was used. Silica (20 mgl(-1)) and phosphate (5.8 mgl(-1)) had no obvious effect on the removal of As(V) and As(III) by TiO2 at neutral pH. Point-of-entry (POE) filters containing 3 l of the granular adsorbent were tested for the removal of arsenic from groundwater in central New Jersey, USA. Groundwater was continuously passed through the filters at an empty bed contact time (EBCT) of 3 min. Approximately 45,000 bed volumes of groundwater containing an average of 39 microgl(-1) of As(V) was treated by the POE filter before the effluent arsenic concentration increased to 10 microgl(-1). The total treated water volumes per weight of adsorbent were about 60,000 l per 1 kg of adsorbent. The field filtration results demonstrated that the granular TiO2 adsorbent was very effective for the removal of arsenic in groundwater.

  10. Film morphology and orientation of amino silicone adsorbed onto cellulose substrate

    NASA Astrophysics Data System (ADS)

    Xu, Yingjun; Yin, Hong; Yuan, Shenfeng; Chen, Zhirong

    2009-07-01

    A series of amino silicones with different amino values were synthesized and adsorbed onto surfaces of cotton fibers and cellulose substrates. The film morphology, hydrophobic properties and surface composition of the silicones are investigated and characterized by field emission scanning electron microscope (FESEM), atomic force microscope (AFM), contact angle measurement, X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared (ATR-IR). The results of the experiments indicate that the amino silicone can form a hydrophobic film on both cotton fibers and cellulose substrates and reduce the surface roughness significantly. Furthermore, the roughness becomes smaller with an increase in the amino value. All these results suggest that the orientation of amino silicone molecule is with the amino functional groups of amino silicone molecule adsorbed onto the cellulose interface while the main polymer chains and the hydrophobic Si-CH 3 groups extend toward the air.

  11. Effects of ammonium application rate on uptake of soil adsorbed amino acids by rice*

    PubMed Central

    Cao, Xiao-chuang; Ma, Qing-xu; Wu, Liang-huan; Zhu, Lian-feng; Jin, Qian-yu

    2016-01-01

    In recent years, excessive use of chemical nitrogen (N) fertilizers has resulted in the accumulation of excess ammonium (NH4 +) in many agricultural soils. Though rice is known as an NH4 +-tolerant species and can directly absorb soil intact amino acids, we still know considerably less about the role of high exogenous NH4 + content on rice uptake of soil amino acids. This experiment examined the effects of the exogenous NH4 + concentration on rice uptake of soil adsorbed glycine in two different soils under sterile culture. Our data showed that the sorption capacity of glycine was closely related to soils’ physical and chemical properties, such as organic matter and cation exchange capacity. Rice biomass was significantly inhibited by the exogenous NH4 + content at different glycine adsorption concentrations. A three-way analysis of variance demonstrated that rice glycine uptake and glycine nutritional contribution were not related to its sorption capacity, but significantly related to its glycine:NH4 + concentration ratio. After 21-d sterile cultivation, the rice uptake of adsorbed glycine accounted for 8.8%‒22.6% of rice total N uptake, which indicates that soil adsorbed amino acids theoretically can serve as an important N source for plant growth in spite of a high NH4 + application rate. However, further studies are needed to investigate the extent to which this bioavailability is realized in the field using the 13C, 15N double labeling technology.

  12. Ataxia induced by small amounts of alcohol

    PubMed Central

    Setta, F; Jacquy, J; Hildebrand, J; Manto, M

    1998-01-01

    A patient is described who exhibited cerebellar ataxia after drinking small amounts of alcohol. Intake of 5 g alcohol induced a gaze evoked nystagmus, a scanning speech, a body sway after eye closure, and bilateral postural leg tremor. Kinematic and EMG analysis of fast wrist movements showed normal movements before and marked hypermetria after alcohol intake. Dysmetria was due to abnormal programming of antagonist muscle activity.

 PMID:9728953

  13. Amplification of trace amounts of nucleic acids

    DOEpatents

    Church, George M.; Zhang, Kun

    2008-06-17

    Methods of reducing background during amplification of small amounts of nucleic acids employ careful analysis of sources of low level contamination. Ultraviolet light can be used to reduce nucleic acid contaminants in reagents and equipment. "Primer-dimer" background can be reduced by judicious design of primers. We have shown clean signal-to-noise with as little as starting material as one single human cell (.about.6 picogram), E. coli cell (.about.5 femtogram) or Prochlorococcus cell (.about.3 femtogram).

  14. Desorption corona beam ionisation (DCBI) mass spectrometry for in-situ analysis of adsorbed phenol in cigarette acetate fiber filter.

    PubMed

    Du, Wen; Tang, Li-Juan; Wen, Jian-Hui; Zhong, Ke-Jun; Jiang, Jian-Hui; Wang, Hua; Chen, Bo; Yu, Ru-Qin

    2015-01-01

    The study of spatial distribution characteristics of the adsorbed compounds for absorbent materials has significant importance in understanding the behaviors of aerosols while they migrating in the absorbent materials. Herein, for the first time, desorption corona beam ionization-mass spectrometry (DCBI-MS) has proposed for direct in-situ analysis of adsorbed aerosol for absorbent materials. DCBI is a novel atmospheric pressure chemical ionization (APCI)-related technique developed by our group in recent years. It can facilitate accurately localizing sampling by forming a visible thin corona beam and avoid the risk of sample contamination and matrix interference compared with other similar techniques. The advantages of DCBI-MS allow rapid screening of the spatial distribution characteristics of the adsorbed compounds for absorbent materials. The distribution characteristic of phenol in cigarette filter tip filled with cellulose acetate fiber was studied as a model case for demonstrating the feasibility of the developed method. As a comparison, conventional HPLC was also used for the study of the distribution characteristic of phenol. The results revealed DCBI-MS had highly improved assay simplicity in spatial distribution characteristic analysis of phenol for the acetate fiber tip, therefore, exhibiting a great potential for convenient, rapid and cost-efficient analysis of the spatial distribution characteristic investigation of adsorbed compounds for adsorbent materials.

  15. Structure, Dynamics, and Thermodynamics of Small Molecules Adsorbed in Zeolite Micropores: Simulation and Statistical Mechanics.

    NASA Astrophysics Data System (ADS)

    van Tassel, Paul Robert

    1993-01-01

    This thesis describes a fully detailed molecular simulation and modeling effort aimed at understanding the fundamentals of adsorption and diffusion of small molecules in zeolite micropores. The primary emphasis is on determining the relationship between the structure and chemistry of the zeolite adsorbent and the structure, dynamics, and thermodynamics of the adsorbed phase. Further emphasis is on developing simple, predictive models of zeolite adsorption and diffusion. We begin by presenting a Monte Carlo simulation of single component adsorption of xenon, methane, and argon in zeolite NaA. The form of the adsorbate density distribution indicates the presence of discrete adsorption sites which arrange in polyhedra whose geometry depends on the number and position of zeolite framework ions. Isotherm plateaus are attributed to either (i) a low energy adsorbate configuration or (ii) the saturation of polyhedral sites. Viewing the adsorbed phase as an ordered arrangement differs from the conventional delocalized model, yet it helps explain certain experimental observations. Next, a study of binary mixtures of small molecules in zeolite NaA using the Monte Carlo method is presented. The mixing in the pore is determined to be highly nonideal by comparison to a simple pore volume filling model. Strong selectivity for a more polarizable molecule (xenon) is observed only at low pore loading. At higher pore loading, a smaller, less polarizable molecule (argon) adsorbs selectively at a significantly lower pressure than predicted by the model. This enhanced selectivity is due to the ability of the smaller molecule to pack more efficiently inside of the pore. Finally, we present two simple lattice models whose forms are arrived at following careful consideration of simulation results. The first describes the adsorption of small molecules in a zeolite. A polyhedral lattice is postulated whose neighboring sites interact energetically and entropically. The second model describes

  16. Vibrational Studies of Adsorbate-Induced Reconstruction on Molybdenum Surfaces.

    NASA Astrophysics Data System (ADS)

    Lopinski, Gregory Peter

    Adsorbate-induced rearrangement of the substrate structure strongly modifies the adsorbate-substrate and adsorbate-adsorbate interactions, leading to the complex behavior observed in many chemisorption systems. In this thesis the H/Mo(211), O/Mo(211) and Na/Mo(100) systems have been studied using high resolution electron energy loss spectroscopy (HREELS) to observe vibrations of the adsorbed atoms. The vibrational data is correlated with observations of the long-range order probed by LEED as well as the work function changes induced by adsorption. Adsorbate -induced substrate reconstruction plays an important role in all three of these systems. Studies of the coadsorption systems O+H/Mo(211) and Na+O/Mo(100) indicate how these effects can influence interactions between adsorbates. For H/Mo(211), above 1ML a (1 x 1) to (1 x 2) transition is observed and attributed to modification of the substrate periodicity. Below 1ML, H atoms are bridge bonded and induce local distortions of the substrate. The transition to the (1 x 2) phase involves the ordering of these displacements and occupation of three-fold sites partially populated by conversion of the bridge bonded species. This conversion accounts for the sawtooth-like coverage dependence of the work function. The structural model proposed for this system is also supported by the desorption parameters and partial molar entropy extracted from adsorption isobars. Oxygen adsorption on Mo(211) involves the occupation of multiple binding sites, with both the long-range order and the local geometry of the adsorbate phases strongly temperature dependent. Coadsorption of low coverages of oxygen and hydrogen leads to segregation of the two adsorbates which can be understood in terms of a substrate-mediated repulsive interaction between O and H. For Na/Mo(100), the frequency of the Na-Mo symmetric stretch mode does not shift with coverage although the mode intensity is strongly coverage dependent. The absence of a frequency shift

  17. Lipid monolayers and adsorbed polyelectrolytes with different degrees of polymerization.

    PubMed

    Ortmann, Thomas; Ahrens, Heiko; Lawrenz, Frank; Gröning, Andreas; Nestler, Peter; Günther, Jens-Uwe; Helm, Christiane A

    2014-06-17

    Polystyrene sulfonate (PSS) of different molecular weight M(w) is adsorbed to oppositely charged DODAB monolayers from dilute solutions (0.01 mmol/L). PSS adsorbs flatly in a lamellar manner, as is shown by X-ray reflectivity and grazing incidence diffraction (exception: PSS with M(w) below 7 kDa adsorbs flatly disordered to the liquid expanded phase). The surface coverage and the separation of the PSS chains are independent of PSS M(w). On monolayer compression, the surface charge density increases by a factor of 2, and the separation of the PSS chains decreases by the same factor. Isotherms show that on increase of PSS M(w) the transition pressure of the LE/LC (liquid expanded/liquid condensed) phase transition decreases. When the contour length exceeds the persistence length (21 nm), the transition pressure is low and constant. For low-M(w) PSS (<7 kDa) the LE/LC transition of the lipids and the disordered/ordered transition of adsorbed PSS occur simultaneously, leading to a maximum in the contour length dependence of the transition enthalpy. These findings show that lipid monolayers at the air/water interface are a suitable model substrate with adjustable surface charge density to study the equilibrium conformation of adsorbed polyelectrolytes as well as their interactions with a model membrane.

  18. Synthesis of arsenic graft adsorbents in pilot scale

    NASA Astrophysics Data System (ADS)

    Hoshina, Hiroyuki; Kasai, Noboru; Shibata, Takuya; Aketagawa, Yasushi; Takahashi, Makikatsu; Yoshii, Akihiro; Tsunoda, Yasuhiko; Seko, Noriaki

    2012-08-01

    Synthesis of arsenic (As) adsorbents in pilot scale was carried out with a synthesizing apparatus by radiation-induced graft polymerization of 2-hydroxyethyl methacrylate phosphoric acid monomer (PA), which consists of phosphoric acid mono- (50%) and di- (50%) ethyl methacrylate esters onto a nonwoven cotton fabric (NCF), and following chemical modification by contact with a zirconium (Zr) solution. The apparatus which was equipped with reaction tanks, a washing tank and a pump can produce up to 0.3 m×14 m size of the As(V) adsorbent in one reaction. A degree of grafting of 150% was obtained at an irradiation dose of 20 kGy with 5% of PA solution mixed with deionized water for 1 h at 40 °C. Finally, after Zr(IV) was loaded onto a NCF with 5 mmol/L of Zr(IV) solution, the graft adsorbent for the removal of As(V) was achieved in pilot-scale. The adsorbent which was synthesized in pilot scale was evaluated in batch mode adsorption with 1 ppm (mg/l) of As(V) solution for 2 h at room temperature. As a result, the adsorption capacity for As(V) was 0.02 mmol/g-adsorbent.

  19. Natural material adsorbed onto a polymer to enhance immune function

    PubMed Central

    Reinaque, Ana Paula Barcelos; França, Eduardo Luzía; Scherer, Edson Fredulin; Côrtes, Mayra Aparecida; Souto, Francisco José Dutra; Honorio-França, Adenilda Cristina

    2012-01-01

    Background In this study, we produced poly(ethylene glycol) (PEG) microspheres of different sizes and adsorbing a medicinal plant mixture, and verified their effect in vitro on the viability, superoxide production, and bactericidal activity of phagocytes in the blood. Methods The medicinal plant mixture was adsorbed onto PEG microspheres and its effects were evaluated by flow cytometry and fluorescence microscopy. Results Adsorption of the herbal mixture onto the PEG microspheres was achieved and the particles were internalized by phagocytes. PEG microspheres bearing the adsorbed herbal mixture stimulated superoxide release, and activated scavenging and microbicidal activity in phagocytes. No differences in functional activity were observed when the phagocytes were not incubated with PEG microspheres bearing the adsorbed herbal mixture. Conclusion This system may be useful for the delivery of a variety of medicinal plants and can confer additional protection against infection. The data reported here suggest that a polymer adsorbed with a natural product is a treatment alternative for enhancing immune function. PMID:22956861

  20. Dynamics of adsorbed polymers on attractive homogeneous surfaces

    PubMed Central

    Yang, Qing-Hui; Luo, Meng-Bo

    2016-01-01

    Dynamic behaviors of polymer chains adsorbed on an attractive, homogeneous surface are studied by using dynamic Monte Carlo simulations. The translational diffusion coefficient Dxy parallel to the surface decreases as the intra-polymer attraction strength EPP or the polymer-surface attraction strength EPS increases. The rotational relaxation time τR increases with EPS, but the dependence of τR on EPP is dependent on the adsorption state of the polymer. We find that τR decreases with increasing EPP for a partially adsorbed polymer but it increases with EPP for a fully adsorbed polymer. Scaling relations Dxy ~ N−α and τR ~ Nβ are found for long polymers. The scaling exponent α is independent of EPS for long polymers but increases with EPP from α = 1.06 at EPP = 0. While β ≈ 2.7 is also roughly independent of EPS for the adsorbed polymer at EPP = 0, but β increases with EPS at EPP > 0. Moreover, we find that β always decreases with increasing EPP. Our results reveal different effects of the attractive surface on the diffusion and rotation of adsorbed polymers. PMID:27849002

  1. Performance of mango seed adsorbents in the adsorption of anthraquinone and azo acid dyes in single and binary aqueous solutions.

    PubMed

    Dávila-Jiménez, Martín M; Elizalde-González, María P; Hernández-Montoya, Virginia

    2009-12-01

    In this study the husk of mango seed and two carbonaceous adsorbents prepared from it were used to study the adsorption behavior of eight acid dyes. The adsorbed amount in mmol m(-2) decayed asymptotically as the molecular volume and area increased. The interaction between the studied dyes and the mesoporous carbon was governed by the ionic species in solution and the acidic/basic groups on the surface. Less than 50% of the external surface of the microporous carbon became covered with the dyes molecules, though monolayer formation demonstrating specific interactions only with active sites on the surface and the adsorption magnitudes correlated with the shape parameter of the molecule within a particular dye group. The adsorption behavior in mixtures was determined by the molecular volume of the constituents; the greater the molecular volume difference, the greater the effect on the adsorbed amount. We also demonstrated that the raw husk of the mango seed can be used to remove up to 50% from model 50 mg l(-1) solutions of the studied acid dyes.

  2. In vitro evaluation of the capacity of zeolite and bentonite to adsorb aflatoxin B1 in simulated gastrointestinal fluids.

    PubMed

    Thieu, N Q; Pettersson, H

    2008-09-01

    Anin vitro study using single concentration and isotherm adsorption was carried out to evaluate the capacity of Vietnamese produced zeolite and bentonite to adsorb aflatoxin B1 (AFB1) in simulated gastrointestinal fluids (SGFs), and a commercial sorbent hydrated sodium calcium aluminosilicate (HSCAS) was used as reference. In this study, AFB1 solution was mixed with sorbents (0.3, 0.4 and 0.5% w/v) in SGFs at pH 3 and pH 7 and shaken for 8 h, centrifuged and the supernatant measured by Vicam fluorometer. Adsorption of AFB1 onto zeolite and bentonite varied according to the pH of SGFs and was lower than HSCAS. Linearity between the increased amount of AFB1 adsorbed on sorbents and the decrease of sorbent concentration was observed for bentonite and HSCAS, except for zeolite in SGFs at pH 7. The observed maximum amounts of AFB1 adsorbed on bentonite and HSCAS were 1.54 and 1.56 mg/g, respectively. The adsorption capacities of bentonite and HSCAS for AFB1 were 12.7 and 13.1 mg/g, respectively, from fitting the data to the Freundlich isotherm equation. Improvement in processing and purification for bentonite is needed to enhance the surface area, which would probably result in better adsorptive capacity for this sorbent.

  3. Lotus Dust Mitigation Coating and Molecular Adsorber Coating

    NASA Technical Reports Server (NTRS)

    O'Connor, Kenneth M.; Abraham, Nithin S.

    2015-01-01

    NASA Goddard Space Flight Center has developed two unique coating formulations that will keep surfaces clean and sanitary and contain contaminants.The Lotus Dust Mitigation Coating, modeled after the self-cleaning, water-repellant lotus leaf, disallows buildup of dust, dirt, water, and more on surfaces. This coating, has been successfully tested on painted, aluminum, glass, silica, and some composite surfaces, could aid in keeping medical assets clean.The Molecular Adsorber Coating is a zeolite-based, sprayable molecular adsorber coating, designed to prevent outgassing in materials in vacuums. The coating works well to adsorb volatiles and contaminates in manufacturing and processing, such as in pharmaceutical production. The addition of a biocide would also aid in controlling bacteria levels.

  4. Method of recovering adsorbed liquid compounds from molecular sieve columns

    DOEpatents

    Burkholder, Harvey R.; Fanslow, Glenn E.

    1983-01-01

    Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed.

  5. Method of recovering adsorbed liquid compounds from molecular sieve columns

    DOEpatents

    Burkholder, H.R.; Fanslow, G.E.

    1983-12-20

    Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed. 8 figs.

  6. NMR study of n-dodecane adsorbed on graphite.

    PubMed

    Alba, M D; Castro, M A; Clarke, S M; Perdigón, A C

    2003-05-01

    In this brief contribution we demonstrate that 1H and 2H NMR spectroscopy can be an effective method of investigating adsorption from liquids at the solid-liquid interface. The method is illustrated here with the adsorption of a simple alkane adsorbed on graphite, in particular the system n-dodecane and graphite at coverages of 1 and 5 monolayers. Static single-pulse proton nuclear magnetic resonance and static quadrupolar echo deuterium nuclear magnetic resonance spectra were recorded for both coverages. The experimental NMR results presented here show features clearly consistent with earlier calorimetric and neutron scattering work and demonstrate the formation of solid adsorbed layers that coexist with the bulk adsorbate with both isotopes. This ability to probe both deuterated and protonated materials simultaneously illustrates that this experimental approach can be readily extended to investigate the adsorption behaviour of multicomponent mixtures.

  7. Adsorption of lead ions on composite biopolymer adsorbent

    SciTech Connect

    Seki, Hideshi; Suzuki, Akira

    1996-04-01

    A fundamental study about the application of biopolymers to the recovery of lead from dilute solution was carried out. A membranous composite biopolymer adsorbent containing two kind of biopolymers, alginic acid (AA) and humic acid (HA), was prepared. HA, which has high solubility in water, was almost completely immobilized in the adsorbent by a combination of calcium alginate gel and activated carbon powder. A general model for complexation between divalent metal ions and acidic sites on biopolymers was applied to explain the adsorption mechanism of lead on the adsorbent (HA-M). The results showed that the complexation constants and the complexation capacities of lead-AA and lead-HA systems were scarcely influenced by immobilization.

  8. ESR spectra of VO2+ ions adsorbed on calcium phosphates.

    PubMed

    Oniki, T; Doi, Y

    1983-07-01

    The ESR spectra of oxovanadium(IV) ions, (VO2+), adsorbed on hydroxyapatite(OHAp), fluorhydroxyapatite(FHAp), Mg-containing tricalcium phosphate(Mg-TCP), .octacalcium phosphate (OCP), dicalcium phosphate dihydrate (DCPD), and amorphous calcium phosphate(ACP) were measured at room temperature. The ESR parameters of VO2+ adsorbed on these compounds were slightly different from one another and accordingly, the ESR technique by use of VO2+ was useful for an analysis of the calcium phosphates precipitated from supersaturated solutions. The ESR parameters of VO2+ adsorbed on ACP and Mg-TCP were found to be very similar to each other, suggesting that ACP and TCP resemble each other in the structure of their crystal surfaces.

  9. Modified Mesoporous Silica (SBA–15) with Trithiane as a new effective adsorbent for mercury ions removal from aqueous environment

    PubMed Central

    2014-01-01

    Background Removal of mercury from aqueous environment has been highly regarded in recent years and different methods have been tested for this purpose. One of the most effective ways for mercury ions (Hg+2) removal is the use of modified nano porous compounds. Hence, in this work a new physical modification of mesoporous silica (SBA-15) with 1, 3, 5 (Trithiane) as modifier ligand and its application for the removal of Hg+2 from aqueous environment has been investigated. SBA-15 and Trithiane were synthesized and the presence of ligand in the silica framework was demonstrated by FTIR spectrum. The amounts of Hg+2 in the samples were determined by cold vapor generation high resolution continuum source atomic absorption spectroscopy. Also, the effects of pH, stirring time and weight of modified SBA-15 as three major parameters for effective adsorption of Hg+2 were studied. Results The important parameter for the modification of the adsorbent was Modification ratio between ligand and adsorbent in solution which was 1.5. The results showed that the best Hg+2 removal condition was achieved at pH = 5.0, stirring time 15 min and 15.0 mg of modified adsorbent. Moreover, the maximum percentage removal of Hg+2 and the capacity of adsorbent were 85% and 10.6 mg of Hg+2/g modified SBA-15, respectively. Conclusions To sum up, the present investigation introduced a new modified nano porous compound as an efficient adsorbent for removal of Hg+2 from aqueous environment. PMID:25097760

  10. A new polymeric ionic liquid-based magnetic adsorbent for the extraction of inorganic anions in water samples.

    PubMed

    Chen, Lei; Huang, Xiaojia; Zhang, Yong; Yuan, Dongxing

    2015-07-17

    In this work, a novel type of polymeric ionic liquid (PIL)-based magnetic adsorbent was successfully synthesized and applied for the extraction and determination of seven inorganic anions in water samples by coupling with ion chromatography. The new adsorbent was synthesized by simple free radical copolymerization of 1-ally-3-vinylimidazolium chloride, ethylene glycol dimethacrylate and silica-coated magnetite. The adsorbent exhibited well-defined core-shell structure and good magnetic response ability. Furthermore, due to the presence of abundant anion-exchange groups in the PIL, the adsorbent displayed expected extraction performance for anions including F(-), Cl(-), Br(-), NO2(-), NO3(-), PO4(3-) and SO4(2-). Various experimental parameters that could affect the extraction performance, such as the amount of adsorbent, desorption solvent, extraction and desorption time, the pH value of sample solution were investigated in detail. Under the optimized conditions, low limits of detection (S/N=3) and quantification limits (S/N=10) of the proposed method for the target anions were achieved within the range of 0.061-0.73μg/L and 0.19-2.41μg/L, respectively. The repeatability was investigated by evaluating the intra-day, inter-day precisions and batch-to-batch reproducibility with relative standard deviations (RSDs) lower than 11%. At the same time, the method also showed high extraction speed, simplicity, practicality and low cost for the extraction inorganic anions. Finally, the proposed method was used to detect anions in different water samples successfully. The recoveries were in the range of 71.0-111%, and the RSDs were below 12% in the all cases.

  11. Adsorbent selection for endosulfan removal from water environment.

    PubMed

    Sudhakar, Y; Dikshit, A K

    1999-01-01

    In the present study, an attempt was made to select a low cost adsorbing material for the removal of endosulfan [C,C'-(1,4,5,6,7,7-hexachloro-8,9,10- trinorborn-5-en-2,3-ylene)(dimethylsulphite)] from water. Various low cost adsorbents like wood charcoal, kimberlite tailings, silica, macro fungi sojar caju were tried with activated charcoal as reference material. The above materials were selected from various sources encompassing organic, inorganic, clayey, and biological sources. For the selection of suitable adsorbent for endosulfan uptake, maximum adsorption capacity (Qmax) was chosen as the parameter. Kinetic profiles of removal were generated for all the materials to assess the equilibrium time. Equilibrium studies were carried out for all materials to assess the adsorption equilibrium model that they followed. The model that gave the best correlation coefficient by linear regression analysis, was adopted for the calculation of Qmax of the corresponding adsorbent material. Using linearised forms of equilibrium models like Langmuir, BET, and Freundlich, maximum adsorptive capacities were determined. Activated charcoal showed the best adsorptive capacity with Qmax of 2.145 mg/g followed by wood charcoal 1.773 mg/g, sojar caju 1.575 mg/g, kimberlite tailings 0.8821 mg/g, and silica 0.3231 mg/g. Albeit activated charcoal gave better performance, it was not considered as a candidate material because of its high cost. Wood charcoal was the next best adsorbent with Qmax 1.773 mg/g. Therefore, wood charcoal was chosen as the best material for endosulfan removal. The study of physical and chemical characteristics of wood charcoal revealed that it is a potential adsorbent and can even be improved further.

  12. Experimental characterization of adsorbed protein orientation, conformation, and bioactivity

    PubMed Central

    Thyparambil, Aby A.; Wei, Yang; Latour, Robert A.

    2015-01-01

    Protein adsorption on material surfaces is a common phenomenon that is of critical importance in many biotechnological applications. The structure and function of adsorbed proteins are tightly interrelated and play a key role in the communication and interaction of the adsorbed proteins with the surrounding environment. Because the bioactive state of a protein on a surface is a function of the orientation, conformation, and accessibility of its bioactive site(s), the isolated determination of just one or two of these factors will typically not be sufficient to understand the structure–function relationships of the adsorbed layer. Rather a combination of methods is needed to address each of these factors in a synergistic manner to provide a complementary dataset to characterize and understand the bioactive state of adsorbed protein. Over the past several years, the authors have focused on the development of such a set of complementary methods to address this need. These methods include adsorbed-state circular dichroism spectropolarimetry to determine adsorption-induced changes in protein secondary structure, amino-acid labeling/mass spectrometry to assess adsorbed protein orientation and tertiary structure by monitoring adsorption-induced changes in residue solvent accessibility, and bioactivity assays to assess adsorption-induced changes in protein bioactivity. In this paper, the authors describe the methods that they have developed and/or adapted for each of these assays. The authors then provide an example of their application to characterize how adsorption-induced changes in protein structure influence the enzymatic activity of hen egg-white lysozyme on fused silica glass, high density polyethylene, and poly(methyl-methacrylate) as a set of model systems. PMID:25708632

  13. Extracting uranium from seawater: Promising AF series adsorbents

    SciTech Connect

    Das, Sadananda; Oyola, Y.; Mayes, Richard T.; Janke, Christopher James; Kuo, Li-Jung; Gill, Gary; Wood, Jordana; Dai, Sheng

    2015-11-02

    Here, a new family of high surface area polyethylene fiber adsorbents (AF series) was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series of were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/co-monomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154 354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8 ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged from 170-200 g-U/kg-ads irrespective of %DOG. A monomer/co-monomer mol ratio in the range of 7.57-10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at Pacific Northwest National Laboratory (PNNL) using flow-through exposure uptake experiments to determine uranium loading capacity with varying KOH conditioning time at 80 C. The highest adsorption capacity of AF1 measured after 56 days of marine testing was demonstrated as 3.9 g-U/kg-adsorbent and 3.2 g-U/kg-adsorbent for 1hr and 3hrs of KOH conditioning at 80 C, respectively. Based on capacity values of several AF1 samples, it was observed that changing KOH conditioning from 3hrs to 1hr at 80 C resulted in 22-27% increase in uranium loading capacity in seawater.

  14. Extracting uranium from seawater: Promising AF series adsorbents

    DOE PAGES

    Das, Sadananda; Oyola, Y.; Mayes, Richard T.; ...

    2015-11-02

    Here, a new family of high surface area polyethylene fiber adsorbents (AF series) was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series of were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/co-monomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154 354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8more » ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged from 170-200 g-U/kg-ads irrespective of %DOG. A monomer/co-monomer mol ratio in the range of 7.57-10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at Pacific Northwest National Laboratory (PNNL) using flow-through exposure uptake experiments to determine uranium loading capacity with varying KOH conditioning time at 80 C. The highest adsorption capacity of AF1 measured after 56 days of marine testing was demonstrated as 3.9 g-U/kg-adsorbent and 3.2 g-U/kg-adsorbent for 1hr and 3hrs of KOH conditioning at 80 C, respectively. Based on capacity values of several AF1 samples, it was observed that changing KOH conditioning from 3hrs to 1hr at 80 C resulted in 22-27% increase in uranium loading capacity in seawater.« less

  15. Structure and dynamics of highly adsorbed semiflexible polymer melts

    NASA Astrophysics Data System (ADS)

    Carrillo, Jan-Michael; Cheng, Shiwang; Kumar, Rajeev; Goswami, Monojoy; Sokolov, Alexie; Sumpter, Bobby

    2015-03-01

    We present a detailed analysis of coarse-grained molecular dynamics simulations of melts of semi-flexible polymer chains in the presence of an adsorbing substrate. For polymer chains located far from the substrate the chain conformations follow the worm-like chain model, in contrast to the reflected Gaussian conformation near the substrate. This is demonstrated in the chain center-of-mass distribution normal to the substrate and the probability of a polymer chain ends to be the closest to the substrate. Both quantities agree with Silberberg's derivation for an ideal chain in the presence of a reflecting wall. We characterized the adsorbed chains and counted the number of loops and tails. For stiff chains, a tail and an adsorbed segment dominate the chain conformation of the adsorbed layer. Also, the mean-square end-to-end distance normal to the substrate is proportional to the normal component of the mean-square end-to-end distance of the tails. The tails do not follow the worm-like chain model and exhibit a stretched conformation. This picture for the adsorbed layer is akin to the ``polydisperse pseudobrush'' envisioned by Guiselin. We probe the dynamics of the segments by calculating the layer (z-)resolved intermediate coherent collective dynamics structure factor, S(q,t,z), for q values equivalent to the bond length. The segment dynamics is slower for stiffer chains. In the adsorbed layer, dynamics is slowed down and can be described by two relaxation times. Department of Energy, Office of Science DE-AC05-00OR227.

  16. Magnetically modified sheaths of Leptothrix sp. as an adsorbent for Amido black 10B removal

    NASA Astrophysics Data System (ADS)

    Angelova, Ralitsa; Baldikova, Eva; Pospiskova, Kristyna; Safarikova, Mirka; Safarik, Ivo

    2017-04-01

    The goal of this study was to assess the biosorption of Amido black 10B dye from aqueous solutions on magnetically modified sheaths of Leptothrix sp. in a batch system. The magnetic modification of the sheaths was performed using both microwave synthesized iron oxide nano- and microparticles and perchloric acid stabilized ferrofluid. The native and both magnetically modified sheaths were characterized by SEM. Various parameters significantly affecting the adsorption process, such as pH, contact time, temperature and initial concentration, were studied in detail using the adsorbent magnetized by both methods. The highest adsorption efficiency was achieved at pH 2. The maximum adsorption capacities of both types of magnetized material at room temperature were found to be 339.2 and 286.1 mg of dye per 1 g of ferrofluid modified and microwave synthesized particles modified adsorbent, respectively. Thermodynamic study of dye adsorption revealed a spontaneous and endothermic process in the temperature range between 279.15 and 313.15 K. The data were fitted to various equilibrium and kinetic models. Experimental data matched well with the pseudo-second-order kinetics and Freundlich isotherm model. The Leptothrix sheaths have excellent efficacy for dye adsorption. This material can be used as an effective, low-cost adsorbent.

  17. Anomalous conformational transitions in cytochrome C adsorbing to Langmuir-Blodgett films

    NASA Astrophysics Data System (ADS)

    Sankaranarayanan, Kamatchi; Nair, B. U.; Dhathathreyan, A.

    2013-05-01

    Helix to beta conformational transitions in proteins has attracted much attention due to their relevance to fibril formation which is implicated in many neurological diseases. This study reports on unusual conformational transition of cytochrome C adsorbing to hydrophilic surface containing pure cationic lipid and mixed Langmuir-Blodgett films (LB films) of cationic and neutral lipids. Evidence for conformational changes of the protein from its native helical state to beta sheet comes from Circular dichroic spectroscopy (CD spectroscopy). Analysis of these samples using High resolution TEM (HRTEM) shows a typical fibrillar pattern with each strand spacing of about 0.41 nm across which can be attributed to the repeat distance of interdigitated neighboring hydrogen-bonded ribbons in a beta sheet. Changes in contact angles of protein adsorbing to the LB films together with the increased mass uptake of water using quartz crystal microbalance (QCM) confirm the role of positive charges in the conformational transition. Dehydration of the protein resulting from the excess water entrainment in the polar planes of the cationic lipid in hydrophilic surface seems to trigger the refolding of the protein to beta sheet while it retains its native conformation in hydrophobic films. The results suggest that drastic conformational changes in CytC adsorbing to cationic lipids may be of significance in its role as a peripheral membrane protein.

  18. Particles adsorbed at various non-aqueous liquid-liquid interfaces.

    PubMed

    Fernandez-Rodriguez, Miguel Angel; Binks, Bernard P; Rodriguez-Valverde, Miguel Angel; Cabrerizo-Vilchez, Miguel Angel; Hidalgo-Alvarez, Roque

    2017-02-07

    Particles adsorbed at liquid interfaces are commonly used to stabilise water-oil Pickering emulsions and water-air foams. The fundamental understanding of the physics of particles adsorbed at water-air and water-oil interfaces is improving significantly due to novel techniques that enable the measurement of the contact angle of individual particles at a given interface. The case of non-aqueous interfaces and emulsions is less studied in the literature. Non-aqueous liquid-liquid interfaces in which water is replaced by other polar solvents have properties similar to those of water-oil interfaces. Nanocomposites of non-aqueous immiscible polymer blends containing inorganic particles at the interface are of great interest industrially and consequently more work has been devoted to them. By contrast, the behaviour of particles adsorbed at oil-oil interfaces in which both oils are immiscible and of low dielectric constant (ε<3) is scarcely studied. Hydrophobic particles are required to stabilise these oil-oil emulsions due to their irreversible adsorption, high interfacial activity and elastic shell behaviour.

  19. Synthesis, characterization and adsorption performance of a novel post-crosslinked adsorbent.

    PubMed

    Zeng, Xiaowei; Yao, Hongjie; Ma, Ning; Fan, Yunge; Wang, Chunhong; Shi, Rongfu

    2011-02-01

    In this paper a post-crosslinked polymeric adsorbent PDHT-2 with high specific surface area was prepared by Friedel-Crafts reaction of the pendant vinyl groups without an externally added crosslinking agent. It was obvious that both the specific surface area and the pore volume of starting copolymer PDHT-1 increased significantly after post-crosslinking. Batch adsorption runs of phenol from aqueous solution onto adsorbent PDHT-1 and PDHT-2 were researched, and commercial macroporous resin XAD-4 was chosen for comparison purpose. Experimental results showed that the adsorption isotherms could be fitted by Langmuir model and Freundlich model and the adsorption capacity onto PDHT-2 was much larger than that onto PDHT-1 and XAD-4 with respect to phenol and phenolic compound, which possibly resulted from its larger specific surface area. The adsorption process for phenol onto the three adsorbents was proved to be exothermic and spontaneous in nature. The thermodynamic parameters such as Gibb's free energy (ΔG), change in enthalpy (ΔH) and change in entropy (ΔS) had been calculated. The adsorption kinetic curves obeyed the pseudo-second order model and the intraparticle diffusion process was the rate-controlling step.

  20. Covalent triazine-based framework: A promising adsorbent for removal of perfluoroalkyl acids from aqueous solution.

    PubMed

    Wang, Bingyu; Lee, Linda S; Wei, Chenhui; Fu, Heyun; Zheng, Shourong; Xu, Zhaoyi; Zhu, Dongqiang

    2016-09-01

    Perfluoroalkyl acids (PFAAs) are highly stable, persistent, and ubiquitous in the environment with significant concerns growing with regards to both human and ecosystem health. Due to the high stability to both biological and chemical attack, the only currently feasible approach for their removal from water is adsorbent technology. The main objective of this study was to assess a covalent triazine-based framework (CTF) adsorbent for removal from aqueous solutions of perfluoro C4, C6, and C8 carboxylates and sulfonates including the two C8s most commonly monitored, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Adsorption affinity and capacity were quantified and compared to three commonly used sorbents: pulverized microporous activated carbon, single-walled carbon nanotubes, and Amberlite IRA-400 anion-exchange resin. CTF adsorbent exhibited pronouncedly higher adsorption affinity and capacity of PFAAs than other test sorbents. The remarkably strong adsorption to CTF can be attributed to the favored electrostatic interaction between the protonated triazine groups on the inner wall of the hydrophobic CTF pore and the negatively charged head groups of the PFAAs intercalated between the CTF layers. The homogeneous, nanosized pores (1.2 nm) of CTF hindered adsorption of a large-sized dissolved humic acid, thus minimizing the suppression of PFAA adsorption. Additionally, regeneration of CTF was easily accomplished by simply raising pH > 11, which inhibited the electrostatic adsorptive interaction of PFAAs.

  1. Stability of a Benzyl Amine Based CO2 Capture Adsorbent in View of Regeneration Strategies

    PubMed Central

    2017-01-01

    In this work, the chemical and thermal stability of a primary amine-functionalized ion-exchange resin (Lewatit VP OC 1065) is studied in view of the potential options of regenerating this sorbent in a CO2 removal application. The adsorbent was treated continuously in the presence of air, different O2/CO2/N2 mixtures, concentrated CO2, and steam, and then the remaining CO2 adsorption capacity was measured. Elemental analysis, BET/BJH analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis were applied to characterize adsorbent properties. This material was found to be thermally and hydrothermally stable at high temperatures. However, significant oxidative degradation occurred already at moderate temperatures (above 70 °C). Temperatures above 120 °C lead to degradation in concentrated dry CO2. Adding moisture to the concentrated CO2 stream improves the CO2-induced stability. Adsorbent regeneration with nitrogen stripping is studied with various parameters, focusing on minimizing the moles of purge gas required per mole of CO2 desorbed.

  2. Coherent anti-Stokes Raman scattering enhancement of thymine adsorbed on graphene oxide

    PubMed Central

    2014-01-01

    Coherent anti-Stokes Raman scattering (CARS) of carbon nanostructures, namely, highly oriented pyrolytic graphite, graphene nanoplatelets, graphene oxide, and multiwall carbon nanotubes as well CARS spectra of thymine (Thy) molecules adsorbed on graphene oxide were studied. The spectra of the samples were compared with spontaneous Raman scattering (RS) spectra. The CARS spectra of Thy adsorbed on graphene oxide are characterized by shifts of the main bands in comparison with RS. The CARS spectra of the initial nanocarbons are definitely different: for all investigated materials, there is a redistribution of D- and G-mode intensities, significant shift of their frequencies (more than 20 cm-1), and appearance of new modes about 1,400 and 1,500 cm-1. The D band in CARS spectra is less changed than the G band; there is an absence of 2D-mode at 2,600 cm-1 for graphene and appearance of intensive modes of the second order between 2,400 and 3,000 cm-1. Multiphonon processes in graphene under many photon excitations seem to be responsible for the features of the CARS spectra. We found an enhancement of the CARS signal from thymine adsorbed on graphene oxide with maximum enhancement factor about 105. The probable mechanism of CARS enhancement is discussed. PMID:24948887

  3. Quantitative trait loci controlling amounts and types of epicuticular waxes in onion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural variation exists in onion (Allium cepa L.) for amounts and types of epicuticular waxes on leaves. Wild-type waxy onion possesses copious amounts of these waxes, while the foliage of semi-glossy and glossy phenotypes accumulate significantly less wax. Reduced amounts of epicuticular waxes hav...

  4. Optimisation of the detection of bacterial proteases using adsorbed immunoglobulins as universal substrates.

    PubMed

    Abuknesha, Ram A; Jeganathan, Fiona; Wildeboer, Dirk; Price, Robert G

    2010-06-15

    Bacterial proteases, Type XXIV from Bacillus licheniformens and Type XIV from Streptomyces griseus, were used to investigate the utility and optimisation of a solid phase assay for proteases, using immunoglobulin proteins as substrates. Immunoglobulins IgA and IgG were adsorbed on to surfaces of ELISA plates and exposed to various levels of the bacterial proteases which led to digestion and desorption of proportional amounts of the immunoglobulins. The assay signal was developed by measuring the remaining proteins on the polystyrene surface with appropriate enzyme-labelled anti-immunoglobulin reagents. The assay was fully optimised in terms of substrate levels employing ELISA techniques to titrate levels of adsorbed substrates and protease analytes. The critical factor which influences assay sensitivity was found to be the substrate concentration, the levels of adsorbed immunoglobulins. The estimated detection limits for protease XXIV and XIV were 10micro units/test and 9micro units/test using IgA as a substrate. EC(50) values were calculated as 213 and 48micro units/test for each protease respectively. Using IgG as a substrate, the estimated detection limits were 104micro units/test for protease XXIV and 9micro units/test for protease XIV. EC(50) values were calculated at 529micro units/test and 28micro units/test for protease XXIV and XIV respectively. The solid phase protease assay required no modification of the substrates and the adsorption step is merely simple addition of immunoglobulins to ELISA plates. Adsorption of the immunoglobulins to polystyrene enabled straightforward separation of reaction mixtures prior to development of assay signal. The assay exploits the advantages of the technical facilities of ELISA technology and commercially available reagents enabling the detection and measurement of a wide range of proteases. However, the key issue was found to be that in order to achieve the potential performance of the simple assay, optimisation of the

  5. Adsorption Removal of Environmental Hormones of Dimethyl Phthalate Using Novel Magnetic Adsorbent

    PubMed Central

    Chang, Chia-Chi; Tseng, Jyi-Yeong; Ji, Dar-Ren; Chiu, Chun-Yu; Lu, De-Sheng; Chang, Ching-Yuan; Yuan, Min-Hao; Chang, Chiung-Fen; Chiou, Chyow-San; Chen, Yi-Hung; Shie, Je-Lueng

    2015-01-01

    Magnetic polyvinyl alcohol adsorbent M-PVAL was employed to remove and concentrate dimethyl phthalate DMP. The M-PVAL was prepared after sequential syntheses of magnetic Fe3O4 (M) and polyvinyl acetate (M-PVAC). The saturated magnetizations of M, M-PVAC, and M-PVAL are 57.2, 26.0, and 43.2 emu g−1 with superparamagnetism, respectively. The average size of M-PVAL by number is 0.75 μm in micro size. Adsorption experiments include three cases: (1) adjustment of initial pH (pH0) of solution to 5, (2) no adjustment of pH0 with value in 6.04–6.64, and (3) adjusted pH0 = 7. The corresponding saturated amounts of adsorption of unimolecular layer of Langmuir isotherm are 4.01, 5.21, and 4.22 mg g−1, respectively. Values of heterogeneity factor of Freundlich isotherm are 2.59, 2.19, and 2.59 which are greater than 1, revealing the favorable adsorption of DMP/M-PVAL system. Values of adsorption activation energy per mole of Dubinin-Radushkevich isotherm are, respectively, of low values of 7.04, 6.48, and 7.19 kJ mol−1, indicating the natural occurring of the adsorption process studied. The tiny size of adsorbent makes the adsorption take place easily while its superparamagnetism is beneficial for the separation and recovery of micro adsorbent from liquid by applying magnetic field after completion of adsorption. PMID:26258169

  6. Systemic antibody response to nano-size calcium phospate biocompatible adjuvant adsorbed HEV-71 killed vaccine

    PubMed Central

    2015-01-01

    Purpose Since 1980s, human enterovirus-71 virus (HEV-71) is one of the common infectious disease in Asian Pacific region since late 1970s without effective commercial antiviral or protective vaccine is unavailable yet. The work examines the role of vaccine adjuvant particle size and the route of administration on postvaccination antibody response towards HEV-71 vaccine adsorbed to calcium phosphate (CaP) adjuvant. Materials and Methods First, CaP nano-particles were compared to a commercial micro-size and vaccine alone. Secondly, intradermal reduced dosage was compared to the conventional intramuscular immunization. Killed HEV-71 vaccines adsorbed to CaP nano-size (73 nm) and commercial one of micro-size (1.7 µm) were administered through intradermal, intramuscular, rabbits received vaccine alone and unvaccinated animals. Results CaP nano-particles adsorbed HEV-71 vaccine displayed higher antibody than the micro-size or unadsorbed vaccine alone, through both parenteral immunization routes. Moreover, the intradermal route (0.5 µg/mL) of 0.1-mL volume per vaccine dose induced equal IgG antibody level to 1.0-mL intramuscular route (0.5 µg/mL). Conclusion The intradermal vaccine adsorbed CaP nano-adjuvant showed safer and significant antibody response after one-tenth reduced dose quantity (0.5 µg/mL) of only 0.1-mL volume as the most suitable protective, cost effective and affordable formulation not only for HEV-71; but also for developing further effective vaccines toward other human pathogens. PMID:25649429

  7. AC microcalorimetry of adsorbates on evaporated metal films: Orientational ordering of H{sub 2} multilayers

    SciTech Connect

    Phelps, R.B.

    1991-11-01

    We have improved and extended a novel ac calorimetric technique for measuring the heat capacity of adsorbates on evaporated metal films. Metallic substrates are of particular interest in current studies of the thermodynamics of adsorbed molecules. The method described in the present work is only calorimetric technique which allows measurements of molecules on simple metallic surfaces. Among other improvements, we have achieved significant progress in the preparation and characterization of the evaporated metal film. We have applied this novel technique to a study of hydrogen multilayers on gold and sapphire substrates. We have shown that samples of normal-hydrogen with a nominal coverage n of approximately 25 monolayers (ML) undergo a bulk-like orientational ordering transition. The transition is suppressed as the coverage is decreased, and no sign of the transition remains above 1.6 K for n {approx} 1 ML. For n {approx_lt} 8 ML, the peak in the heat capacity exhibits signs of finite-size effects. At higher coverages, finite-size effects are not observed, and the shape of the peak depends strongly on the substrate. We conclude that the peak is inhomogeneously broadened for n {approx_lt} 8 ML. This work represents the first measurements of the heat capacity due to orientational ordering in adsorbed hydrogen. The results of an earlier experiment involving vibrational spectroscopy of adsorbed molecules are included in the Appendix. In this work, we have used infrared emission spectroscopy to study the spectral region in the vicinity of the C=O stretch vibration of bridge-bonded CO on Pt(111).

  8. AC microcalorimetry of adsorbates on evaporated metal films: Orientational ordering of H sub 2 multilayers

    SciTech Connect

    Phelps, R.B.

    1991-11-01

    We have improved and extended a novel ac calorimetric technique for measuring the heat capacity of adsorbates on evaporated metal films. Metallic substrates are of particular interest in current studies of the thermodynamics of adsorbed molecules. The method described in the present work is only calorimetric technique which allows measurements of molecules on simple metallic surfaces. Among other improvements, we have achieved significant progress in the preparation and characterization of the evaporated metal film. We have applied this novel technique to a study of hydrogen multilayers on gold and sapphire substrates. We have shown that samples of normal-hydrogen with a nominal coverage n of approximately 25 monolayers (ML) undergo a bulk-like orientational ordering transition. The transition is suppressed as the coverage is decreased, and no sign of the transition remains above 1.6 K for n {approx} 1 ML. For n {approx lt} 8 ML, the peak in the heat capacity exhibits signs of finite-size effects. At higher coverages, finite-size effects are not observed, and the shape of the peak depends strongly on the substrate. We conclude that the peak is inhomogeneously broadened for n {approx lt} 8 ML. This work represents the first measurements of the heat capacity due to orientational ordering in adsorbed hydrogen. The results of an earlier experiment involving vibrational spectroscopy of adsorbed molecules are included in the Appendix. In this work, we have used infrared emission spectroscopy to study the spectral region in the vicinity of the C=O stretch vibration of bridge-bonded CO on Pt(111).

  9. Removing adsorbed heavy metal ions from sand surfaces via applying interfacial properties of rhamnolipid.

    PubMed

    Haryanto, Bode; Chang, Chien-Hsiang

    2015-01-01

    In this study, the interfacial properties of biosurfactant rhamnolipid were investigated and were applied to remove adsorbed heavy metal ions from sand surfaces with flushing operations. The surface tension-lowering activity, micelle charge characteristic, and foaming ability of rhamnolipid were identified first. For rhamnolipid in water, the negatively charged characteristic of micelles or aggregates was confirmed and the foaming ability at concentrations higher than 40 mg/L was evaluated. By using the rhamnolipid solutions in a batch washing approach, the potential of applying the interfacial properties of rhamnolipid to remove adsorbed copper ions from sand surfaces was then demonstrated. In rhamnolipid solution flushing operations for sand-packed medium, higher efficiency was found for the removal of adsorbed copper ions with residual type than with inner-sphere interaction type, implying the important role of interaction type between the copper ion and the sand surface in the removal efficiency. In addition, the channeling effect of rhamnolipid solution flow in the sand-packed medium was clearly observed in the solution flushing operations and was responsible for the low removal efficiency with low contact areas between solution and sand. By using rhamnolipid solution with foam to flush the sand-packed medium, one could find that the channeling effect of the solution flow was reduced and became less pronounced with the increase in the rhamnolipid concentration, or with the enhanced foaming ability. With the reduced channeling effect in the flushing operations, the removal efficiency for adsorbed copper ions was significantly improved. The results suggested that the foam-enhanced rhamnolipid solution flushing operation was efficient in terms of surfactant usage and operation time.

  10. Random registry shifts in quasi-one-dimensional adsorbate systems

    NASA Astrophysics Data System (ADS)

    Schäfer, J.; Erwin, S. C.; Hansmann, M.; Song, Z.; Rotenberg, E.; Kevan, S. D.; Hellberg, C. S.; Horn, K.

    2003-02-01

    The apparent contradiction of one-dimensional adsorbate chains on Si(111) having a 3×2 unit cell and yet a 3×1 diffraction pattern is resolved for the example of Ba/Si(111)-(3×2). Random registry shifts between adsorbate chains are observed in tunneling microscopy, with very short interchain correlation lengths. Fourier analysis provides a natural explanation for a pseudo-(3×1) diffraction pattern. Within density-functional theory such registry shifts can occur with essentially negligible energy cost, leading to entropy-driven, virtually perfect disorder. Substrate states of high symmetry and one-dimensional character are inferred to promote this phenomenon.

  11. Ordering and phase separation of adsorbed binary mixtures

    NASA Astrophysics Data System (ADS)

    Mahale, N. K.; Cole, M. W.

    1986-10-01

    The ground state energy is calculated for mixtures adsorbed on graphite and Ag surfaces. The graphite case considers noble gases adsorbed in a commensurate array, while for Ag the substrate is ignored except for its mediation of the interatomic interaction. The balance between alternative possible structures is sensitive to the assumed interaction, for which realistic potential models are employed. Comparison is made with predictions based on simple combining rules. The cases of Ar mixtures with N 2 or CO on graphite are treated, including both herringbone and pinwheel structures for the N 2. Finite temperature behavior is described qualitatively.

  12. Random registry shifts in quasi-one-dimensional adsorbate systems

    SciTech Connect

    Schafer, J.; Erwin, S.C.; Hansmann, M.; Song, Z.; Rotenberg, E.; Kevan, S.D.; Hellberg, C.S.; Horn, K.

    2003-02-18

    The apparent contradiction of one-dimensional adsorbate chains on Si(111) having a 3x2 unit cell and yet a 3x1 diffraction pattern is resolved for the example of Ba/Si(111)-(3x2). Random registry shifts between adsorbate chains are observed in tunneling microscopy, with very short interchain correlation lengths. Fourier analysis provides a natural explanation for a pseudo-(3x1) diffraction pattern. Within density-functional theory such registry shifts can occur with essentially negligible energy cost, leading to entropy-driven, virtually perfect disorder. Substrate states of high symmetry and one-dimensional character are inferred to promote this phenomenon.

  13. Mass transport of adsorbates near a discontinuous structural phase transition

    NASA Astrophysics Data System (ADS)

    Granato, E.; Ying, S. C.; Elder, K. R.; Ala-Nissila, T.

    2016-12-01

    We study the mass transport dynamics of an adsorbed layer near a discontinuous incommensurate striped-honeycomb phase transition via numerical simulations of a coarse-grained model focusing on the motion of domain walls rather than individual atoms. Following an initial step profile created in the incommensurate striped phase, an intermediate hexagonal incommensurate phase nucleates and grows, leading to a bifurcation into two sharp profiles propagating in opposite directions as opposed to broad profiles induced by atomic diffusive motion. Our results are in agreement with recent numerical simulations of a microscopic model as well as experimental observations for the Pb/Si(111) adsorbate system.

  14. Structure of adsorbed organometallic rhodium: model single atom catalysts.

    PubMed

    Bennett, R A; McCavish, N D; Basham, M; Dhanak, V R; Newton, M A

    2007-02-02

    We have determined the structure of a complex rhodium carbonyl chloride [Rh(CO)2Cl] molecule adsorbed on the TiO2(110) surface by the normal incidence x-ray standing wave technique. The data show that the technique is applicable to reducible oxide systems and that the dominant adsorbed species is undissociated with Rh binding atop bridging oxygen and to the Cl found close to the fivefold coordinated Ti ions in the surface. A minority geminal dicarbonyl species, where Rh-Cl bond scission has occurred, is found bridging the bridging oxygen ions forming a high-symmetry site.

  15. Significant Tsunami Events

    NASA Astrophysics Data System (ADS)

    Dunbar, P. K.; Furtney, M.; McLean, S. J.; Sweeney, A. D.

    2014-12-01

    Tsunamis have inflicted death and destruction on the coastlines of the world throughout history. The occurrence of tsunamis and the resulting effects have been collected and studied as far back as the second millennium B.C. The knowledge gained from cataloging and examining these events has led to significant changes in our understanding of tsunamis, tsunami sources, and methods to mitigate the effects of tsunamis. The most significant, not surprisingly, are often the most devastating, such as the 2011 Tohoku, Japan earthquake and tsunami. The goal of this poster is to give a brief overview of the occurrence of tsunamis and then focus specifically on several significant tsunamis. There are various criteria to determine the most significant tsunamis: the number of deaths, amount of damage, maximum runup height, had a major impact on tsunami science or policy, etc. As a result, descriptions will include some of the most costly (2011 Tohoku, Japan), the most deadly (2004 Sumatra, 1883 Krakatau), and the highest runup ever observed (1958 Lituya Bay, Alaska). The discovery of the Cascadia subduction zone as the source of the 1700 Japanese "Orphan" tsunami and a future tsunami threat to the U.S. northwest coast, contributed to the decision to form the U.S. National Tsunami Hazard Mitigation Program. The great Lisbon earthquake of 1755 marked the beginning of the modern era of seismology. Knowledge gained from the 1964 Alaska earthquake and tsunami helped confirm the theory of plate tectonics. The 1946 Alaska, 1952 Kuril Islands, 1960 Chile, 1964 Alaska, and the 2004 Banda Aceh, tsunamis all resulted in warning centers or systems being established.The data descriptions on this poster were extracted from NOAA's National Geophysical Data Center (NGDC) global historical tsunami database. Additional information about these tsunamis, as well as water level data can be found by accessing the NGDC website www.ngdc.noaa.gov/hazard/

  16. Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

    SciTech Connect

    Gill, Gary A.; Kuo, Li-Jung; Strivens, Jonathan E.; Wood, Jordana R.; Schlafer, Nicholas J.; Janke, Christopher J.; Das, Sadananda; Mayes, Richard; Saito, Tomonori; Brown, Suree S.; Tsouris, Constantinos; Tsouris, Costas; Wai, Chien M.; Pan, Horng-Bin

    2016-09-29

    The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL’s Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includes other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL’s Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980’s (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U/kg adsorbent for a

  17. 29 CFR 4219.14 - Amount of liability for 20-year-limitation amounts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... amount equal to the present value of all initial withdrawal liability payments for which the employer was not liable pursuant to section 4219(c)(1)(B) of ERISA. The present value of such payments shall...

  18. Removal of Direct Red 12B by garlic peel as a cheap adsorbent: Kinetics, thermodynamic and equilibrium isotherms study of removal

    NASA Astrophysics Data System (ADS)

    Asfaram, A.; Fathi, M. R.; Khodadoust, S.; Naraki, M.

    2014-06-01

    The removal of dyes from industrial waste is very important from health and hygiene point of view and for environmental protection. In this work, efficiency and performance of garlic peel (GP) adsorbent for the removal of Direct Red 12B (DR12B) from wastewater was investigated. The influence of variables including pH, concentration of the dye and amount of adsorbent, particle size, contact time and temperature on the dye removal has been investigated. It was observed that the pseudo-second-order kinetic model fits better with good correlation coefficient and the equilibrium data fitted well with the Langmuir model. More than 99% removal efficiency was obtained within 25 min at adsorbent dose of 0.2 g per 50 ml for initial dye concentration of 50 mg L-1. Calculation of various thermodynamic parameters such as, Gibb's free energy, entropy and enthalpy of the on-going adsorption process indicate feasibility and endothermic nature of DR12B adsorption.

  19. Ultrasonic Atomization Amount for Different Frequencies

    NASA Astrophysics Data System (ADS)

    Yasuda, Keiji; Honma, Hiroyuki; Xu, Zheng; Asakura, Yoshiyuki; Koda, Shinobu

    2011-07-01

    The mass flow rate of ultrasonic atomization was estimated by measuring the vaporization amount from a bulk liquid with a fountain. The effects of ultrasonic frequency and intensity on the atomization characteristics were investigated when the directivities of the acoustic field from a transducer were almost the same. The sample was distillated water and the ultrasonic frequencies were 0.5, 1.0, and 2.4 MHz. The mass flow rate of ultrasonic atomization increased with increasing ultrasonic intensity and decreasing ultrasonic frequency. The fountain was formed at the liquid surface where the effective value of acoustic pressure was above atmospheric pressure. The fountain height was strongly governed by the acoustic pressure at the liquid surface of the transducer center. At the same ultrasonic intensity, the dependence of ultrasonic frequency on the number of atomized droplets was small. At the same apparent surface area of the fountain, the number of atomized droplets became larger as the ultrasonic frequency increased.

  20. Kinetic Assembly of Near-IR Active Gold Nanoclusters using Weakly Adsorbing Polymers to Control Size

    PubMed Central

    Tam, Jasmine M.; Murthy, Avinash K.; Ingram, Davis R.; Nguyen, Robin; Sokolov, Konstantin V.; Johnston, Keith P.

    2013-01-01

    Clusters of metal nanoparticles with an overall size less than 100 nm and high metal loadings for strong optical functionality, are of interest in various fields including microelectronics, sensors, optoelectronics and biomedical imaging and therapeutics. Herein we assemble ~5 nm gold particles into clusters with controlled size, as small as 30 nm and up to 100 nm, which contain only small amounts of polymeric stabilizers. The assembly is kinetically controlled with weakly adsorbing polymers, PLA(2K)-b-PEG(10K)-b-PLA(2K) or PEG (MW = 3350), by manipulating electrostatic, van der Waals (VDW), steric, and depletion forces. The cluster size and optical properties are tuned as a function of particle volume fractions and polymer/gold ratios to modulate the interparticle interactions. The close spacing between the constituent gold nanoparticles and high gold loadings (80–85% w/w gold) produce a strong absorbance cross section of ~9×10−15 m2 in the NIR at 700 nm. This morphology results from VDW and depletion attractive interactions that exclude the weakly adsorbed polymeric stabilizer from the cluster interior. The generality of this kinetic assembly platform is demonstrated for gold nanoparticles with a range of surface charges from highly negative to neutral, with the two different polymers. PMID:20361735

  1. Protein-Adsorbed Magnetic-Nanoparticle-Mediated Assay for Rapid Detection of Bacterial Antibiotic Resistance.

    PubMed

    Cowger, Taku A; Yang, Yaping; Rink, David E; Todd, Trever; Chen, Hongmin; Shen, Ye; Yan, Yajun; Xie, Jin

    2017-02-17

    Antibiotic susceptibility tests have been used for years as a crucial diagnostic tool against antibiotic-resistant bacteria. However, due to a lack of biomarkers specific to resistant types, these approaches are often time-consuming, inaccurate, and inflexible in drug selections. Here, we present a novel susceptibility test method named protein-adsorbed nanoparticle-mediated matrix-assisted laser desorption-ionization mass spectrometry, or PANMS. Briefly, we adsorb five different proteins (β-casein, α-lactalbumin, human serum albumin, fibrinogen, and avidin) onto the surface of Fe3O4. Upon interaction with bacteria surface, proteins were displaced from the nanoparticle surface, the amounts of which were quantified by matrix-assisted laser desorption ionization mass spectrometry. We find that the protein displacement profile was different distinctive among different bacteria strains and, in particular, between wild-type and drug-resistant strains. More excitingly, we observe bacteria resistant to drugs of the same mechanisms share similar displacement profiles on a linear discriminant analysis (LDA) map. This suggests the possibility of using PANMS to identify the type of mechanism behind antibiotic resistance, which was confirmed in a blind test. Given that PANMS is free of drug incubation and the whole procedure takes less than 50 min, it holds great potential as a high-throughput, low-cost, and accurate drug susceptibility test in the clinic.

  2. Low-cost adsorbents from bio-waste for the removal of dyes from aqueous solution.

    PubMed

    Manoj Kumar Reddy, P; Mahammadunnisa, Sk; Ramaraju, B; Sreedhar, B; Subrahmanyam, Ch

    2013-06-01

    Activated carbons (ACs) were developed from bio-waste materials like rice husk and peanut shell (PS) by various physicochemical activation methods. PS char digested in nitric acid followed by treatment at 673 K resulted in high surface area up to ∼585 m(2)/g. The novelty of the present study is the identification of oxygen functional groups formed on the surface of activated carbons by infrared and X-ray photoelectron spectroscopy and quantification by using temperature programmed decomposition (TPD). Typical TPD data indicated that each activation method may lead to varying amounts of acidic and basic functional groups on the surface of the adsorbent, which may be a crucial factor in determining the adsorption capacity. It was shown that ACs developed during the present study are good adsorbents, especially for the removal of a model textile dye methylene blue (MB) from aqueous solution. As MB is a basic dye, H(2)O(2)-treated rice husk showed the best adsorption capacity, which is in agreement with the acidic groups present on the surface. Removal of the dye followed Langmuir isotherm model, whereas MB adsorption on ACs followed pseudo-second-order kinetics.

  3. Application of fly ash as an adsorbent for Estradiol in animal waste.

    PubMed

    Norris, Pauline; Hagan, Stephanie; Cohron, Martin; Zhao, Houying; Pan, Wei-Ping; Li, Kawang

    2015-09-15

    The contamination of agricultural ground with estrogen compounds through application of animal wastes is a present concern. At the same time, current uses for waste fly ash having high carbon content are limited. To help mitigate these problems, we examine using waste fly ash as a useful adsorbent for Estradiol in pig waste digests. In this study, Estradiol was added to vials containing water and fly ash from several different power plants. After an extraction process, the amount of Estradiol in the water was measured. Commercial activated carbon was also used for comparison purposes. Vials containing varying concentrations of Estradiol and no trapping material were used as a control. The results from this study indicate that fly ash can be used as a trapping material for Estradiol in water, but that commercially available activated carbon can trap about an order of magnitude more Estradiol than the fly ash and that the effects of the fly ash matrix can both inhibit and promote the solvation of Estradiol into water depending possibly upon pH and cation concentration effects. In addition, preliminary extraction studies using pig waste digest indicate that fly ash can be used as adsorbent for Estradiol present in pig waste.

  4. Cadmium telluride nanoparticles loaded on activated carbon as adsorbent for removal of sunset yellow.

    PubMed

    Ghaedi, M; Hekmati Jah, A; Khodadoust, S; Sahraei, R; Daneshfar, A; Mihandoost, A; Purkait, M K

    2012-05-01

    Adsorption is a promising technique for decolorization of effluents of textile dyeing industries but its application is limited due to requirement of high amounts of adsorbent required. The objective of this study was to assess the potential of cadmium telluride nanoparticles loaded onto activated carbon (CdTN-AC) for the removal of sunset yellow (SY) dye from aqueous solution. Adsorption studies were conducted in a batch mode varying solution pH, contact time, initial dye concentration, CdTN-AC dose, and temperature. In order to investigate the efficiency of SY adsorption on CdTN-AC, pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits better than other kinetic models with good correlation coefficient. Equilibrium data were fitted to the Langmuir model. Thermodynamic parameters such as enthalpy, entropy, activation energy, and sticking probability were also calculated. It was found that the sorption of SY onto CdTN-AC was spontaneous and endothermic in nature. The proposed adsorbent is applicable for SY removal from waste of real effluents including pea-shooter, orange drink and jelly banana with efficiency more than 97%.

  5. A novel approach for arsenic adsorbents regeneration using MgO.

    PubMed

    Tresintsi, Sofia; Simeonidis, Konstantinos; Katsikini, Maria; Paloura, Eleni C; Bantsis, Georgios; Mitrakas, Manassis

    2014-01-30

    An integrated procedure for the regeneration of iron oxy-hydroxide arsenic adsorbents by granulated MgO is proposed in this study. A continuous recirculation configuration, with a NaOH solution flowing sequentially through the saturated adsorbent (leaching step) and the MgO (adsorption step) column beds, was optimized by utilizing the high arsenic adsorption efficiency of MgO at strong alkaline environments. Experimental results indicated that the total amount of leached arsenic was captured by MgO whereas the regenerated iron oxy-hydroxide recovered around 80% of its removal capacity upon reuse. The improved adsorption capacity of MgO for As(V), which is maximized at pH 10, is explained by the intermediate hydration to Mg(OH)2 and the following As(V) oxy-anions adsorption on its surface through the formation of monodentate inner sphere complexes, as it is deduced from the AsK-edge X-ray absorption fine structure (EXAFS) analysis. In addition to the economical-benefits, corresponding tests proved that the solid wastes of this process, namely spent MgO/Mg(OH)2, can be environmentally safely disposed as stable additives in cement products, while the alkaline solution is completely detoxified and can be recycled to the regeneration task.

  6. Cadmium telluride nanoparticles loaded on activated carbon as adsorbent for removal of sunset yellow

    NASA Astrophysics Data System (ADS)

    Ghaedi, M.; Hekmati Jah, A.; Khodadoust, S.; Sahraei, R.; Daneshfar, A.; Mihandoost, A.; Purkait, M. K.

    2012-05-01

    Adsorption is a promising technique for decolorization of effluents of textile dyeing industries but its application is limited due to requirement of high amounts of adsorbent required. The objective of this study was to assess the potential of cadmium telluride nanoparticles loaded onto activated carbon (CdTN-AC) for the removal of sunset yellow (SY) dye from aqueous solution. Adsorption studies were conducted in a batch mode varying solution pH, contact time, initial dye concentration, CdTN-AC dose, and temperature. In order to investigate the efficiency of SY adsorption on CdTN-AC, pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits better than other kinetic models with good correlation coefficient. Equilibrium data were fitted to the Langmuir model. Thermodynamic parameters such as enthalpy, entropy, activation energy, and sticking probability were also calculated. It was found that the sorption of SY onto CdTN-AC was spontaneous and endothermic in nature. The proposed adsorbent is applicable for SY removal from waste of real effluents including pea-shooter, orange drink and jelly banana with efficiency more than 97%.

  7. Intracellular calcium is a target of modulation of apoptosis in MCF-7 cells in the presence of IgA adsorbed to polyethylene glycol

    PubMed Central

    Honorio-França, Adenilda Cristina; Nunes, Gabriel Triches; Fagundes, Danny Laura Gomes; de Marchi, Patrícia Gelli Feres; Fernandes, Rubian Trindade da Silva; França, Juliana Luzia; França-Botelho, Aline do Carmo; Moraes, Lucélia Campelo Albuquerque; Varotti, Fernando de Pilla; França, Eduardo Luzía

    2016-01-01

    Purpose Clinical and epidemiological studies have indicated that breastfeeding has a protective effect on breast cancer risk. Protein-based drugs, including antibodies, are being developed to attain better forms of cancer therapy. Secretory IgA (SIgA) is the antibody class in human breast milk, and its activity can be linked to the protective effect of breastfeeding. The aim of this study was to investigate the effect of polyethylene glycol (PEG) microspheres with adsorbed SIgA on MCF-7 human breast cancer cells. Methods The PEG microspheres were characterized by flow cytometry and fluorescence microscopy. The MCF-7 cells were obtained from American Type Culture Collection. MCF-7 cells were pre-incubated for 24 hours with or without SIgA (100 ng/mL), PEG microspheres or SIgA adsorbed in PEG microspheres (100 ng/mL). Viability, intracellular calcium release, and apoptosis in MCF-7 cells were determined by flow cytometry. Results Fluorescence microscopy and flow cytometry analyses revealed that SIgA was able to adsorb to the PEG microspheres. The MCF-7 cells that were incubated with PEG microspheres with adsorbed SIgA showed decreased viability. MCF-7 cells that were incubated with SIgA or PEG microspheres with adsorbed SIgA had increased intracellular Ca2+ levels. In the presence of SIgA, an increase in the percentage of apoptotic cells was observed. The highest apoptosis index was observed when the cells were treated with PEG microspheres with adsorbed SIgA. Conclusion These data suggest that colostral SIgA adsorbed to PEG microspheres has antitumor effects on human MCF-7 breast cancer cells and that the presence of large amounts of this protein in secreted breast milk may provide protection against breast tumors in women who breastfed. PMID:26893571

  8. Equilibrium, kinetic and sorber design studies on the adsorption of Aniline blue dye by sodium tetraborate-modified Kaolinite clay adsorbent.

    PubMed

    Unuabonah, Emmanuel I; Adebowale, Kayode O; Dawodu, Folasegun A

    2008-09-15

    Raw Kaolinite clay obtained Ubulu-Ukwu, Delta State of Nigeria and its sodium tetraborate (NTB)-modified analogue was used to adsorb Aniline blue dye. Fourier transformed infrared spectra of NTB-modified Kaolinite suggests that modification was effective on the surface of the Kaolinite clay with the strong presence of inner -OH functional group. The modification of Kaolinite clay raised its adsorption capacity from 1666 to 2000 mg/kg. Modeling adsorption data obtained from both unmodified and NTB-modified Kaolinite clay reveals that the adsorption of Aniline blue dye on unmodified Kaolinite clay is on heterogeneous adsorption sites because it followed strongly the Freundlich isotherm equation model while adsorption data from NTB-modified Kaolinite clay followed strongly the Langmuir isotherm equation model which suggest that Aniline blue dye was adsorb homogeneous adsorption sites on the NTB-modified adsorbent surface. There was an observed increase in the amount of Aniline blue adsorbed as initial dye concentration was increased from 10 to 30 mg/L. It was observed that kinetic data obtained generally gave better robust fit to the second-order kinetic model (SOM). The initial sorption rate was found to increased with increasing initial dye concentration (from 10 to 20 mg/L) for data obtained from 909 to 1111 mg kg(-1)min(-1) for unmodified and 3325-5000 mg kg(-1) min(-1) for NTB-modified adsorbents. Thereafter there was a decrease in initial sorption rate with further increase in dye concentration. The linearity of the plots of the pseudo-second-order model with very high-correlation coefficients indicates that chemisorption is involved in the adsorption process. From the design of a single-batch adsorber it is predicted that the NTB-modified Kaolinite clay adsorbent will require 50% less of the adsorbent to treat certain volumes of wastewater containing 30 mg/L of Aniline blue dye when it is compared with the unmodified adsorbent. This will be cost effective in

  9. Fast and efficient protein purification using membrane adsorber systems.

    PubMed

    Suck, Kirstin; Walter, Johanna; Menzel, Frauke; Tappe, Alexander; Kasper, Cornelia; Naumann, Claudia; Zeidler, Robert; Scheper, Thomas

    2006-02-10

    The purification of proteins from complex cell culture samples is an essential step in proteomic research. Traditional chromatographic methods often require several steps resulting in time consuming and costly procedures. In contrast, protein purification via membrane adsorbers offers the advantage of fast and gentle but still effective isolation. In this work, we present a new method for purification of proteins from crude cell extracts via membrane adsorber based devices. This isolation procedure utilises the membranes favourable pore structure allowing high flow rates without causing high back pressure. Therefore, shear stress to fragile structures is avoided. In addition, mass transfer takes place through convection rather than diffusion, thus allowing very rapid separation processes. Based on this membrane adsorber technology the separation of two model proteins, human serum albumin (HSA) and immungluboline G (IgG) is shown. The isolation of human growth hormone (hGH) from chinese hamster ovary (CHO) cell culture supernatant was performed using a cation exchange membrane. The isolation of the enzyme penicillin acylase from the crude Escherichia coli supernatant was achieved using an anion exchange spin column within one step at a considerable purity. In summary, the membrane adsorber devices have proven to be suitable tools for the purification of proteins from different complex cell culture samples.

  10. RADIOLYSIS OF ORGANIC COMPOUNDS IN THE ADSORBED STATE

    DOEpatents

    Sutherland, J.W.; Allen, A.O.

    1961-10-01

    >A method of forming branch chained hydrocarbons by means of energetic penetrating radiation is described. A solid zeolite substrate is admixed with a cobalt ion and is irradiated with a hydrocarbon adsorbed therein. Upon irradiation with gamma rays, there is an increased yield of branched and lower molecular straight chain compounds. (AEC)

  11. Extracting uranium from seawater: Promising AI series adsorbents

    DOE PAGES

    Das, Sadananda; Oyola, Y.; Mayes, Richard T.; ...

    2015-11-10

    A series of adsorbent (AI10 through AI17) were successfully developed at ORNL by radiation induced graft polymerization (RIGP) of acrylonitrile (AN) and vinylphosphonic acid (VPA) (at different mole/mole ratios) onto high surface area polyethylene fiber, with higher degree of grafting which ranges from 110 300%. The grafted nitrile groups were converted to amidoxime groups by reaction with 10 wt% hydroxylamine at 80 C for 72 hours. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8 ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged frommore » 171-187 g-U/kg-ads irrespective of %DOG. The performance of the adsorbents for uranium adsorption in natural seawater was also carried out using flow-through-column at Pacific Northwest National Laboratory (PNNL). The three hours KOH conditioning was better for higher uranium uptake than one hour. The adsorbent AI11 containing AN and VPA at the mole ration of 3.52, emerged as the potential candidate for higher uranium adsorption (3.35 g-U/Kg-ads.) after 56 days of exposure in the seawater in the flow-through-column. The rate vanadium adsorption over uranium was linearly increased throughout the 56 days exposure. The total vanadium uptake was ~5 times over uranium after 56 days.« less

  12. Extracting Uranium from Seawater: Promising AI Series Adsorbents

    SciTech Connect

    Das, S.; Oyola, Y.; Mayes, R. T.; Janke, C. J.; Kuo, L. -J.; Gill, G.; Wood, J. R.; Dai, S.

    2016-04-20

    A new series of adsorbents (AI10 through AI17) were successfully developed at ORNL by radiation induced graft polymerization (RIGP) of acrylonitrile (AN) and vinylphosphonic acid (VPA) (at different mole to mole ratios) onto high surface area polyethylene fiber, with high degrees of grafting (DOG) varying from 110 to 300%. The grafted nitrile groups were converted to amidoxime groups by reaction with 5 wt % hydroxylamine at 80 °C for 72 h. The amidoximated adsorbents were then conditioned with 0.44 M KOH at 80 °C followed by screening at ORNL with prescreening brine spiked with 8 ppm uranium. Uranium adsorption capacities in prescreening ranged from 171 to 187 g-U/kg-ads irrespective of percent DOG. The performance of the adsorbents with respect to uranium adsorption in natural seawater was also investigated using flow-throughcolumn testing at the Pacific Northwest National Laboratory (PNNL). Three hours of KOH conditioning led to higher uranium uptake than 1 h of conditioning. The adsorbent AI11, containing AN and VPA at the mole ratio of 3.52, emerged as the potential candidate for the highest uranium adsorption (3.35 g-U/kg-ads.) after 56 days of exposure in seawater flow-through-columns. The rate of vanadium adsorption over uranium linearly increased throughout the 56 days of exposure. The total mass of vanadium uptake was ~5 times greater than uranium after 56 days.

  13. Enhanced encapsulation of metoprolol tartrate with carbon nanotubes as adsorbent

    NASA Astrophysics Data System (ADS)

    Garala, Kevin; Patel, Jaydeep; Patel, Anjali; Dharamsi, Abhay

    2011-12-01

    A highly water-soluble antihypertensive drug, metoprolol tartrate (MT), was selected as a model drug for preparation of multi-walled carbon nanotubes (MWCNTs)-impregnated ethyl cellulose (EC) microspheres. The present investigation was aimed to increase encapsulation efficiency of MT with excellent adsorbent properties of MWCNTs. The unique surface area, stiffness, strength and resilience of MWCNTs have drawn much anticipation as carrier for highly water-soluble drugs. Carbon nanotubes drug adsorbate (MWCNTs:MT)-loaded EC microspheres were further optimized by the central composite design of the experiment. The effects of independent variables (MWCNTs:MT and EC:adsorbate) were evaluated on responses like entrapment efficiency (EE) and t 50 (time required for 50% drug release). The optimized batch was compared with drug alone EC microspheres. The results revealed high degree of improvement in encapsulation efficiency for MWCNTs:MT-loaded EC microspheres. In vitro drug release study exhibited complete release form drug alone microspheres within 15 h, while by the same time only 50-60% drug was released for MWCNTs-impregnated EC microspheres. The optimized batch was further characterized by various instrumental analyses such as scanning electron microscopy, powder X-ray diffraction and differential scanning calorimetry. The results endorse encapsulation of MWCNTs:MT adsorbate inside the matrix of EC microspheres, which might have resulted in enhanced encapsulation and sustained effect of MT. Hence, MWCNTs can be utilized as novel carriers for extended drug release and enhanced encapsulation of highly water-soluble drug, MT.

  14. EVALUATING VARIOUS ADSORBENTS AND MEMBRANES FOR REMOVING RADIUM FROM GROUNDWATER

    EPA Science Inventory

    Field studies were conducted in Lemont, Ill., to evaluate specific adsorbents and reverse osmosis (RO) membranes for removing radium from groundwater. A radium-selective complexer and barium-sulfate-loaded alumina appeared to have the best potential for low-cost adsorption of ra...

  15. Extracting uranium from seawater: Promising AI series adsorbents

    SciTech Connect

    Das, Sadananda; Oyola, Y.; Mayes, Richard T.; Janke, Christopher James; Kuo, Li-Jung; Gill, Gary; Wood, Jordana; Dai, Sheng

    2015-11-10

    A series of adsorbent (AI10 through AI17) were successfully developed at ORNL by radiation induced graft polymerization (RIGP) of acrylonitrile (AN) and vinylphosphonic acid (VPA) (at different mole/mole ratios) onto high surface area polyethylene fiber, with higher degree of grafting which ranges from 110 300%. The grafted nitrile groups were converted to amidoxime groups by reaction with 10 wt% hydroxylamine at 80 C for 72 hours. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8 ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged from 171-187 g-U/kg-ads irrespective of %DOG. The performance of the adsorbents for uranium adsorption in natural seawater was also carried out using flow-through-column at Pacific Northwest National Laboratory (PNNL). The three hours KOH conditioning was better for higher uranium uptake than one hour. The adsorbent AI11 containing AN and VPA at the mole ration of 3.52, emerged as the potential candidate for higher uranium adsorption (3.35 g-U/Kg-ads.) after 56 days of exposure in the seawater in the flow-through-column. The rate vanadium adsorption over uranium was linearly increased throughout the 56 days exposure. The total vanadium uptake was ~5 times over uranium after 56 days.

  16. Agricultural Waste as Sources for Mercury Adsorbents in Gas Applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased emphasis on reduction of mercury emissions from coal fired electric power plants have resulted in environmental regulations that may in the future require application of activated carbons as mercury sorbents. The sorbents could be injected into the flue gas stream where it adsorbs the mer...

  17. Agricultural By-products as Mercury Adsorbents in Gas Applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased emphasis on reduction of mercury emissions from coal fired electric power plans have resulted in environmental regulations that may in the future require application of activated carbons as mercury sorbents. The sorbents could be injected into the flue gas stream where is adsorbs the merc...

  18. Chemical speciation of adsorbed glycine on metal surfaces

    NASA Astrophysics Data System (ADS)

    Han, Jeong Woo; James, Joanna N.; Sholl, David S.

    2011-07-01

    Experimental studies have reported that glycine is adsorbed on the Cu(110) and Cu(100) surfaces in its deprotonated form at room temperature, but in its zwitterionic form on Pd(111) and Pt(111). In contrast, recent density functional theory (DFT) calculations indicated that the deprotonated molecules are thermodynamically favored on Cu(110), Cu(100), and Pd(111). To explore the source of this disagreement, we have tested three possible hypotheses. Using DFT calculations, we first show that the kinetic barrier for the deprotonation reaction of glycine on Pd(111) is larger than on Cu(110) or Cu(100). We then report that the presence of excess hydrogen would have little influence on the experimentally observed results, especially for Pd(111). Lastly, we perform Monte Carlo simulations to demonstrate that the aggregates of zwitterionic species on Pt(111) are energetically preferred to those of neutral species. Our results strongly suggest that the formation of aggregates with relatively large numbers of adsorbed molecules is favored under experimentally relevant conditions and that the adsorbate-adsorbate interactions in these aggregates stabilize the zwitterionic species.

  19. Hydraulic properties of adsorbed water films in unsaturated porous media

    SciTech Connect

    Tokunaga, Tetsu K.

    2009-03-01

    Adsorbed water films strongly influence residual water saturations and hydraulic conductivities in porous media at low saturations. Hydraulic properties of adsorbed water films in unsaturated porous media were investigated through combining Langmuir's film model with scaling analysis, without use of any adjustable parameters. Diffuse double layer influences are predicted to be important through the strong dependence of adsorbed water film thickness (f) on matric potential ({Psi}) and ion charge (z). Film thickness, film velocity, and unsaturated hydraulic conductivity are predicted to vary with z{sup -1}, z{sup -2}, and z{sup -3}, respectively. In monodisperse granular media, the characteristic grain size ({lambda}) controls film hydraulics through {lambda}{sup -1} scaling of (1) the perimeter length per unit cross sectional area over which films occur, (2) the critical matric potential ({Psi}{sub c}) below which films control flow, and (3) the magnitude of the unsaturated hydraulic conductivity when {Psi} < {Psi}{sub c}. While it is recognized that finer textured sediments have higher unsaturated hydraulic conductivities than coarser sands at intermediate {Psi}, the {lambda}{sup -1} scaling of hydraulic conductivity predicted here extends this understanding to very low saturations where all pores are drained. Extremely low unsaturated hydraulic conductivities are predicted under adsorbed film-controlled conditions (generally < 0.1 mm y{sup -1}). On flat surfaces, the film hydraulic diffusivity is shown to be constant (invariant with respect to {Psi}).

  20. Gd uptake experiments for preliminary set of functionalized adsorbents

    SciTech Connect

    Clinton Noack

    2015-03-16

    These data summarize adsorption experiments conducted with Gd in 0.5 M NaCl. Results represent preliminary, proof-of-concept data utilizing fine-powder silica gel as the adsorbent support. Future testing will focus on larger, application-appropriate beads.

  1. Dispersive kinetic of fluorescence decay of alloxazines adsorbed into cellulose

    NASA Astrophysics Data System (ADS)

    Krawczyk, Alina; Sikorska, Ewa; Khmelinskii, Igor V.; Sikorski, Marek

    2005-09-01

    The fluorescence decay of alloxazines adsorbed into microcrystalline cellulose shows a complex kinetics suggesting at least three emitting species. The exponential series method and the Albery model were used to calculate the underlying distributions, providing results about the decay rate constants or lifetime distributions.

  2. Comparison of natural adsorbents for metal removal from acidic effluent.

    PubMed

    Blais, J F; Shen, S; Meunier, N; Tyagi, R D

    2003-02-01

    Adsorption tests were carried out in acidic synthetic solutions (pH 2.0) using 20 g l(-1) of various natural adsorbents and 0.25 mM of 11 different metals. In decreasing order, the most efficient adsorbents tested were: oyster shells, cedar bark, vermiculite, cocoa shells and peanut shells. In contrast, weak metal adsorption was demonstrated by: red cedar wood, peat moss, pine wood, corn cobs and perlite. Metal adsorption capacities in acidic synthetic solution followed the order: Pb2+> Cr3+> Cu2+> Fe2+> Al3+> Ni2+> Cd2+ > Mn2+ > Zn2+ > Ca2+, Mg2+. Alkaline treatment (0.75 M NaOH) increased the effectiveness of metal removal for the majority of adsorbents. In contrast, acid treatment (0.75 M H2SO4) either reduced or did not affect the adsorption capacity of the materials tested. Finally, oyster shells, red cedar wood, vermiculite, cocoa shells and peanut shells, were effective natural adsorbents for the selective recovery of lead and trivalent chromium from acidic effluent.

  3. High-capacity hydrogen storage in Al-adsorbed graphene

    NASA Astrophysics Data System (ADS)

    Ao, Z. M.; Peeters, F. M.

    2010-05-01

    A high-capacity hydrogen storage medium—Al-adsorbed graphene—is proposed based on density-functional theory calculations. We find that a graphene layer with Al adsorbed on both sides can store hydrogen up to 13.79wt% with average adsorption energy -0.193eV/H2 . Its hydrogen storage capacity is in excess of 6wt% , surpassing U. S. Department of Energy (DOE’s) target. Based on the binding-energy criterion and molecular-dynamics calculations, we find that hydrogen storage can be recycled at near ambient conditions. This high-capacity hydrogen storage is due to the adsorbed Al atoms that act as bridges to link the electron clouds of the H2 molecules and the graphene layer. As a consequence, a two-layer arrangement of H2 molecules is formed on each side of the Al-adsorbed graphene layer. The H2 concentration in the hydrogen storage medium can be measured by the change in the conductivity of the graphene layer.

  4. Activation volumes of enzymes adsorbed on silica particles.

    PubMed

    Schuabb, Vitor; Czeslik, Claus

    2014-12-30

    The immobilization of enzymes on carrier particles is useful in many biotechnological processes. In this way, enzymes can be separated from the reaction solution by filtering and can be reused in several cycles. On the other hand, there is a series of examples of free enzymes in solution that can be activated by the application of pressure. Thus, a potential loss of enzymatic activity upon immobilization on carrier particles might be compensated by pressure. In this study, we have determined the activation volumes of two enzymes, α-chymotrypsin (α-CT) and horseradish peroxidase (HRP), when they are adsorbed on silica particles and free in solution. The experiments have been carried out using fluorescence assays under pressures up to 2000 bar. In all cases, activation volumes were found to depend on the applied pressure, suggesting different compressions of the enzyme-substrate complex and the transition state. The volume profiles of free and adsorbed HRP are similar. For α-CT, larger activation volumes are found in the adsorbed state. However, up to about 500 bar, the enzymatic reaction of α-CT, which is adsorbed on silica particles, is characterized by a negative activation volume. This observation suggests that application of pressure might indeed be useful to enhance the activity of enzymes on carrier particles.

  5. Live microbial cells adsorb Mg2+ more effectively than lifeless organic matter

    NASA Astrophysics Data System (ADS)

    Qiu, Xuan; Yao, Yanchen; Wang, Hongmei; Duan, Yong

    2017-03-01

    The Mg2+ content is essential in determining different Mg-CaCO3 minerals. It has been demonstrated that both microbes and the organic matter secreted by microbes are capable of allocating Mg2+ and Ca2+ during the formation of Mg-CaCO3, yet detailed scenarios remain unclear. To investigate the mechanism that microbes and microbial organic matter potentially use to mediate the allocation of Mg2+ and Ca2+ in inoculating systems, microbial mats and four marine bacterial strains (Synechococcus elongatus, Staphylococcus sp., Bacillus sp., and Desulfovibrio vulgaris) were incubated in artificial seawater media with Mg/Ca ratios ranging from 0.5 to 10.0. At the end of the incubation, the morphology of the microbial mats and the elements adsorbed on them were analyzed using scanning electronic microscopy (SEM) and energy diffraction spectra (EDS), respectively. The content of Mg2+ and Ca2+ adsorbed by the extracellular polysaccharide substances (EPS) and cells of the bacterial strains were analyzed with atomic adsorption spectroscopy (AAS). The functional groups on the surface of the cells and EPS of S. elongatus were estimated using automatic potentiometric titration combined with a chemical equilibrium model. The results show that live microbial mats generally adsorb larger amounts of Mg2+ than Ca2+, while this rarely is the case for autoclaved microbial mats. A similar phenomenon was also observed for the bacterial strains. The living cells adsorb more Mg2+ than Ca2+, yet a reversed trend was observed for EPS. The functional group analysis indicates that the cell surface of S. elongatus contains more basic functional groups (87.24%), while the EPS has more acidic and neutral functional groups (83.08%). These features may be responsible for the different adsorption behavior of Mg2+ and Ca2+ by microbial cells and EPS. Our work confirms the differential Mg2+ and Ca2+ mediation by microbial cells and EPS, which may provide insight into the processes that microbes use to

  6. Nanopore reactive adsorbents for the high-efficiency removal of waste species

    DOEpatents

    Yang, Arthur Jing-Min; Zhang, Yuehua

    2005-01-04

    A nanoporous reactive adsorbent incorporates a relatively small number of relatively larger reactant, e.g., metal, enzyme, etc., particles (10) forming a discontinuous or continuous phase interspersed among and surrounded by a continuous phase of smaller adsorbent particles (12) and connected interstitial pores (14) therebetween. The reactive adsorbent can effectively remove inorganic or organic impurities in a liquid by causing the liquid to flow through the adsorbent. For example, silver ions may be adsorbed by the adsorbent particles (12) and reduced to metallic silver by reducing metal, such as ions, as the reactant particles (10). The column can be regenerated by backwashing with the liquid effluent containing, for example, acetic acid.

  7. Adsorbable organic halogens generation and reduction during degradation of phenol by UV radiation/sodium hypochlorite.

    PubMed

    Zeng, Qing-Fu; Fu, Jie; Shi, Yin-Tao; Xia, Dong-Sheng; Zhu, Hai-Liang

    2009-02-01

    The degradation of phenol by UV radiation/sodium hypochlorite (UV/NaClO) was investigated. The degradation processes were analyzed by a UV-visible spectrometer, total organic carbon analyzer, and gas chromatography-mass spectroscopy. The experimental results indicate that phenol can be photodegraded by UV/NaClO effectively. However, adsorbable organic halogens (AOX) were produced during the degradation process. Analysis of the mechanism of degradation indicates that the decrease in pH value would increase the formation of AOX. Also, dissolved oxygen greatly increased the rate of phenol degradation and reduced the formation of AOX. Therefore, appropriate conditions could increase degradation and inhibit chlorination. Adjusting the pH value and increasing the amount of oxygen were effective methods.

  8. Mapping of the cationic starch adsorbed on pulp fibers by ToF-SIMS

    NASA Astrophysics Data System (ADS)

    Matsushita, Yasuyuki; Suzuki, Ayumi; Sekiguchi, Takuya; Saito, Kaori; Imai, Takanori; Fukushima, Kazuhiko

    2008-12-01

    Cationic starch (CS) is routinely used in the papermaking process to improve the dry strength or printability of paper. The effectiveness depends on the distribution of the starch on the pulp fiber, and in this study, time-of-flight secondary ion mass spectrometry was used to investigate this distribution. The characteristic peak at 58 m/ z was applied to map the CS. Based on the imaging analysis of the handsheets with the CS as an internal additive, the distribution of CS became more uniform with decreasing freeness. The amount of adsorbed CS increased with increasing fiber length and was lower on vessels than on other fibers. These results were related to fibrillation. From the analysis of handsheets with CS as an external additive, the penetration depth of the starch into base paper increased with decreases in the sizing degree of the base paper.

  9. Nuclear DNA Amounts in Macaronesian Angiosperms

    PubMed Central

    SUDA, JAN; KYNCL, TOMÁŠ; FREIOVÁ, RADKA

    2003-01-01

    Nuclear DNA contents for 104 Macaronesian angiosperms, with particular attention on Canary Islands endemics, were analysed using propidium iodide flow cytometry. Prime estimates for more than one‐sixth of the whole Canarian endemic flora (including representatives of 11 endemic genera) were obtained. The resulting 1C DNA values ranged from 0·19 to 7·21 pg for Descurainia bourgeauana and Argyranthemum frutescens, respectively (about 38‐fold difference). The majority of species, however, possessed (very) small genomes, with C‐values <1·6 pg. The tendency towards small nuclear DNA contents and genome sizes was confirmed by comparing average values for Macaronesian and non‐Macaronesian representatives of individual families, genera and major phylogenetic lineages. Our data support the hypothesis that the insular selection pressures in Macaronesia favour small C‐values and genome sizes. Both positive and negative correlations between infrageneric nuclear DNA amount variation and environmental conditions on Tenerife were also found in several genera. PMID:12824074

  10. Chemical characterization of organic carbon dissolved in natural waters using inorganic adsorbents.

    PubMed

    Sugiyama, Y; Kumagai, T

    2001-01-01

    Dissolved organic carbon (DOC) in water samples from Lake Biwa was chemically characterized by two inorganic adsorbents with completely different surface characteristics. The two adsorbents were HIO (hydrous iron oxide) and SG (silica gel). Solutions of reference standard materials were analyzed concerning their adsorption behavior to HIO and SG for bovine serum albumin (BSA), fulvic acid extracted from the bottom sediments of Lake Biwa, phthalic acid, and starch. The adsorption of DOC to HIO was mainly controlled by ligand exchange and electrostatic interaction; that of SG was by electrostatic interaction. It was found that in a weak acid solution of around pH 5, BSA adsorbs to both HIO and SG, but that fulvic acid, phthalic acid and starch only show adsorption to HIO. Using these characteristics, DOC samples in natural water samples were characterized into pro-DOC, which adsorbs to both HIO and SG at pH 5, and car-DOC, which only adsorbs to HIO at pH 5. The DOC samples in Lake Biwa on October 7, 1997, at sampling sites Nb-2 and Nb-5 (south basin of Lake Biwa, the depths were about 2 and 4 m), and Ie-1 (north basin of Lake Biwa, the depth was about 75 m) were characterized. The pro-DOC has different values, depending on their sampling sites and depths, and had the maximum value of 0.42 mg C l(-1) at the surface water of Ie-1, and had the lowest values at middle to deeper water depths (0.18-0.27 mg C l(-1)). The car-DOC showed a relatively stable value at Ie-1 regardless of the depth (0.63-0.83 mg C l(-1)), and the maximum value was observed in Nb-2 and Nb-5 (1.2 and 1.3 mg C l(-1)). The ratios between car-DOC and pro-DOC concentrations were 0.2-0.5, and had different values for different sampling sites and depths. The ratios were significantly different for surface water samples where the biological activities are high and for bottom water samples where decomposition predominates.

  11. Mechanical properties of hexadecane-water interfaces with adsorbed hydrophobic bacteria

    NASA Astrophysics Data System (ADS)

    Kang, Zhewen

    Certain strains of hydrophobic bacteria are known to play critical roles in petroleum-related applications. The aim of this study was to investigate how hydrophobic bacteria in their stationary phase could adsorb onto the hexadecane-water interface and alter its mechanical properties. The two strains of bacteria used in forming the interfacial films were Acinetobacter venetianus RAG-1 (a Gram-negative bacterium) and Rhodococcus erythropolis 20S-E1-c (Gram-positive). Experiments at two different length scales (millimetre and micrometre) were conducted and the results were compared. In addition, a simple flow experiment was designed in a constricted channel and the results were related to the intrinsic mechanical properties of bacteria-adsorbed films. On the millimetre scale, using the pendant drop technique, the film interfacial tension was monitored as the surface area was made to undergo changes. Under static conditions, both types of bacteria showed no significant effect on the interfacial tension. When subjected to transient excitations, the two bacterial films exhibited qualitatively similar, yet quantitative distinct rheological properties (including film elasticities and relaxation times). Under continuous reduction of surface area, the RAG-1 system showed a "paper-like" interface, while the interface of the 20S-E1-c system was "soap film-like." These macroscopic observations could be explained by the surface ultrastructures of the two cell strains. On the micrometre scale, using the micropipette technique, colloidal stability of the bacteria-coated oil droplets was examined through direct-contact experiments. Both types of bacteria were seen to function as effective stabilizers. In addition, the adsorbed bacteria also interacted with one another at the interface, giving rise to higher order 2-D rheological properties. A technique of directly probing the mechanical properties of the emulsion drop surfaces revealed that (a) the films behaved as purely elastic

  12. Optimum Tolerance Design Using Component-Amount and Mixture-Amount Experiments

    SciTech Connect

    Piepel, Gregory F.; Ozler, Cenk; Sehirlioglu, Ali Kemal

    2013-08-01

    One type of tolerance design problem involves optimizing component and assembly tolerances to minimize the total cost (sum of manufacturing cost and quality loss). Previous literature recommended using traditional response surface (RS) designs and models to solve this type of tolerance design problem. In this article, component-amount (CA) and mixture-amount (MA) approaches are proposed as more appropriate for solving this type of tolerance design problem. The advantages of the CA and MA approaches over the RS approach are discussed. Reasons for choosing between the CA and MA approaches are also discussed. The CA and MA approaches (experimental design, response modeling, and optimization) are illustrated using real examples.

  13. Takovite-aluminosilicate@MnFe2O4 nanocomposite, a novel magnetic adsorbent for efficient preconcentration of lead ions in food samples.

    PubMed

    Kardar, Zahra Shakeri; Beyki, Mostafa Hossein; Shemirani, Farzaneh

    2016-10-15

    Here in we report preparation of MnFe2O4 and magnetic takovite-aluminosilicate adsorbent via precipitation methodology. The synthesized nanocomposite was applied in preconcentration of Pb(2+) ions from various matrices. The structural, surface, and magnetic characteristics of the adsorbent were investigated by XRD, EDX, FE-SEM, and VSM techniques. Several parameters affecting preconcentration efficiency, including sample pH, contact time, adsorbent amount, and sample volume were studied and optimized. Under optimized conditions, the calibration graph was linear in the range of 2.0-100μgL(-1), the relative standard deviation was 3.00% (n=5), the limit of detection was 0.67μgL(-1), and the enrichment factor was 70.0. The maximum adsorption capacity of the adsorbent was calculated to be 69.9mgg(-1). The suggested method was successfully applied in determination of trace amount of Pb(2+) ions in water and food samples.

  14. Nano porous alkaline earth metal silicates as free fatty acid adsorbents from Crude Palm Oil (CPO)

    NASA Astrophysics Data System (ADS)

    Masmur, Indra; Sembiring, Seri Bima; Bangun, Nimpan; Kaban, Jamaran; Putri, Nabila Karina

    2017-01-01

    Free fatty acids(FFA) from Crude Palm Oil (CPO) have been adsorbed by alkaline earth metal silicate (M-silicate : M = Mg, Ca, Sr and Ba) adsorbents in ethanol using batch method. The adsorbents were prepared from the chloride salts of alkaline metals and Na2SiO3. The resulting white solid of the alkaline earth metal silicates were then heated at 800°C for 3 hours to enlarge their porosities. All adsorbents were characterized by SEM-EDX, XRD and BET. The EDX spectrum of SEM-EDX showed the appearance of all elements in the adsorbents, and the XRD spectrum of all adsorbents showed that they have crystobalite structure. The porosity of the adsorbents calculated by BET method showed that the porosities of the adsorbents range from 2.0884 - 2.0969 nm. All the adsorbents were used to adsorb the FFA from CPO containing 4.79%, 7.3%, 10.37% and 13.34% of FFA. The ratio of adsorbent to CPO to be used in adsorption of FFA from CPO were made 1:1, 1:2 and 1:3, with adsorption time of 1 hour. We found that the maximum adsorption of FFA from CPO was given by Ca-Silicate adsorbent which was between 69.86 - 94.78%, while the lowest adsorption was shown by Mg-silicate adsorbent which was 49.32 -74.53%.

  15. In situ ion gun cleaning of surface adsorbates and its effect on electrostatic forces

    NASA Astrophysics Data System (ADS)

    Schafer, Robert; Xu, Jun; Mohideen, Umar

    2016-01-01

    To obtain precise measurements of the Casimir force, it is crucial to take into account the electrostatic interactions that exist between the two boundaries. Two otherwise grounded conductors will continue to have residual electrostatic effects from patch potentials existing on the surfaces. In this paper, we look at the effect of in situ cleaning of adsorbate patches, and the resultant effect on the net electrostatic potential difference between two surfaces. We find a significant reduction in the residual potential due to in situ Ar+ cleaning for the samples used.

  16. 24 CFR 576.45 - Reallocation of grant amounts; returned or unused amounts.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DEVELOPMENT, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT COMMUNITY FACILITIES EMERGENCY SHELTER GRANTS PROGRAM... or unused amounts. (a) General. From time to time, HUD will reallocate emergency shelter grant... and Shelter Program administered by the Federal Emergency Management Agency, as a resource to...

  17. 24 CFR 576.45 - Reallocation of grant amounts; returned or unused amounts.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DEVELOPMENT, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT COMMUNITY FACILITIES EMERGENCY SHELTER GRANTS PROGRAM... or unused amounts. (a) General. From time to time, HUD will reallocate emergency shelter grant... and Shelter Program administered by the Federal Emergency Management Agency, as a resource to...

  18. 76 FR 59138 - Medicare Program; Medicare Appeals; Adjustment to the Amount in Controversy Threshold Amounts for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-23

    ..., respectively, for Medicare Part A and Part B appeals. Section 940 of the Medicare Prescription Drug... the consumer price index for all urban consumers (U.S. city average) for July 2003 to July of the year... (Prescription Drug Plan) Appeals The annually adjusted AIC threshold amounts for ALJ hearings and...

  19. Surface modification of chromatography adsorbents by low temperature low pressure plasma.

    PubMed

    Arpanaei, A; Winther-Jensen, B; Theodosiou, E; Kingshott, P; Hobley, T J; Thomas, O R T

    2010-10-29

    before and after exposure to plasmas enabled effective modification depths within hydrated Q HyperZ adsorbent particles to be calculated as 0.2-1.2 μm, depending on the conditions applied. The depth of plasma induced alteration was strongly influenced by the power input and size of the treated batch, i.e. dropping the power or increasing the batch size resulted in reduced plasma penetration and therefore shallower modification. The selectivity of 'surface vs. core' modification imparted to Q HyperZ by the various plasma treatments was evaluated in static and dynamic binding studies employing appropriate probes, i.e. plasmid DNA, sonicated calf thymus DNA and bovine serum albumin. In static binding studies performed with adsorbents that had been exposed to plasmas at the 5 g scale (25 g L(-1) of plasma reactor), the highest 'surface/core' modification selectivity was observed for Q HyperZ that had been subjected to 3 h of air plasma etching at 220 V (35.8 W L(-1)). This treatment removed ∼53% of 'surface' DNA binding at the expense of a 9.3% loss in 'core' protein binding. Even more impressive results were obtained in dynamic expanded bed adsorption studies conducted with Q HyperZ adsorbents that had been treated with air (220 V, 3 h) and 'vinyl acetate/argon' (170 V, 3 h) plasmas at 10.5 g scale (52.5 g L(-1) of plasma reactor). Following both plasma treatments: the 10% breakthrough capacities of the modified Q HyperZ adsorbents towards 'surface' binding DNA probes dropped very significantly (30-85%); the DNA induced inter-particle cross-linking and contraction of expanded beds observed during application of sonicated DNA on native Q HyperZ was completely eradicated; but the 'core' protein binding performance remained unchanged cf. that of the native Q HyperZ starting material.

  20. Green coconut shells applied as adsorbent for removal of toxic metal ions using fixed-bed column technology.

    PubMed

    Sousa, Francisco W; Oliveira, André G; Ribeiro, Jefferson P; Rosa, Morsyleide F; Keukeleire, Denis; Nascimento, Ronaldo F

    2010-08-01

    This study applies green coconut shells as adsorbent for the removal of toxic metal ions from aqueous effluents using column adsorption. The results show that a flow rate of 2 mL/min and a bed height of 10 cm are most feasible. Furthermore, larger amounts of effluent can be treated for removal of single ions. The breakthrough curves for multiple elements gave the order of adsorption capacity: Cu(+2) > Pb(+2) > Cd(+2) > Zn(+2) > Ni(+2). Real samples arising from the electroplating industry can be efficiently handled.

  1. Silver and zinc oxide nanostructures loaded on activated carbon as new adsorbents for removal of methylene green: a comparative study.

    PubMed

    Ghaedi, M; Karimi, H; Yousefi, F

    2014-09-01

    In this study, the removal of methylene green (MG) from aqueous solution based on two new adsorbents including silver nanoparticles and zinc oxide nanorods loaded on activated carbon (Ag-NP-AC and ZnO-NR-AC, respectively) has been carried out. The dependency of removal process to variables such as contact time, pH, amount of adsorbents, and initial MG concentration were examined and optimized. It was found that the maximum MG removal percentage was achieved at pH = 7.0 following stirring at 400 r min(-1) for 7 and 6 min for Ag-NP-AC and ZnO-NR-AC, respectively. Equilibrium data were well fitted with the Langmuir model having maximum adsorption capacity of 166.7 and 200 mg g(-1) for Ag-NP-AC and ZnO-NR-AC, respectively. Thermodynamic parameters of MG adsorption on Ag-NP-AC such as enthalpy and entropy changes, activation energy, sticking probability, and Gibbs free energy changes show the spontaneous and endothermic nature of the removal process. Among different conventional kinetic models, the pseudo second-order kinetics in addition to particle diffusion mechanism is the best and efficient model for the prediction and explanation of experimental data of MG adsorption onto both adsorbents.

  2. Poly(ionic liquid) immobilized magnetic nanoparticles as new adsorbent for extraction and enrichment of organophosphorus pesticides from tea drinks.

    PubMed

    Zheng, Xiaoyan; He, Lijun; Duan, Yajing; Jiang, Xiuming; Xiang, Guoqiang; Zhao, Wenjie; Zhang, Shusheng

    2014-09-05

    New poly(ionic liquid) immobilized magnetic nanoparticles (PIL-MNPs) were synthesized via co-polymerization of 1-vinyl-3-hexylimidazolium-based ionic liquid and vinyl-modified magnetic particles and were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and magnetic measurements. The PIL-MNPs were utilized as adsorbent phases in magnetic solid-phase extraction (MSPE). The extraction and enrichment efficiency were evaluated by using four organophosphorus pesticides (parathion, fenthion, phoxim and temephos) as test analytes. Various parameters, such as amount of adsorbent, adsorption time, desorption solvent and time, and ionic strength were investigated. The proposed method showed good linearity for the analytes in the concentration range of 1-200μgL(-1) with a correlation coefficient (R)>0.9963. Low limit of detection of 0.01μgL(-1) and high enrichment factors ranging from 84 to 161 were achieved. The proposed method has been successfully used to determine organophosphorus pesticides from three tea drink samples with satisfactory recovery of 81.4-112.6% and RSDs of 4.5-11.3%. The PIL-MNP adsorbent can be reused for 20 times without a noticeable decrease in extraction efficiency.

  3. [Removal of nitrate from aqueous solution using cetylpyridinium chloride (CPC)-modified activated carbon as the adsorbent].

    PubMed

    Zheng, Wen-Jing; Lin, Jian-Wei; Zhan, Yan-Hui; Fang, Qiao; Yang, Meng-Juan; Wang, Hong

    2013-11-01

    Surfactant-modified activated carbon (SMAC) was prepared by loading cetylpyridinium chloride (CPC) onto activated carbon and used as adsorbents to remove nitrate from aqueous solution. The SMAC was effective for removing nitrate from aqueous solution. The SMAC exhibited much higher nitrate adsorption capacity than that of the unmodified activated carbon. The nitrate adsorption capacity for SMAC increased with increasing the CPC loading. The adsorption kinetics of nitrate on SMAC followed a pseudo-second-order kinetic model. The equilibrium adsorption data of nitrate on SMAC could be described by the Langmuir isotherm model. Based on the Langmuir isotherm model, the maximum nitrate adsorption capacity for SMAC with CPC loading amount of444 mmol per 1 kg activated carbon was determined to be 16.1 mg x g(-1). The nitrate adsorption capacity for SMAC decreased with the increasing solution pH. The presence of competing anions such as chloride, sulfate and bicarbonate reduced the nitrate adsorption capacity. The nitrate adsorption capacity for SMAC slightly decreased with the increasing reaction temperature. Almost 95% of nitrate molecules adsorbed on SMAC could be desorbed in 1 mol x L(-1) NaCl solution. The main mechanisms for the adsorption of nitrate on SMAC are anionic exchange and electrostatic attraction. The results of this work indicate that SMAC is a promising adsorbent for removing nitrate from aqueous solution.

  4. Photoelectric response of purple membrane fragments adsorbed on a lipid monolayer supported by mercury and characterization of the resulting interphase.

    PubMed

    Dolfi, Andrea; Aloisi, Giovanni; Guidelli, Rolando

    2002-09-01

    Purple membrane (PM) fragments were adsorbed on a dioleoylphosphatidylcholine (DOPC) monolayer supported by mercury to investigate the kinetics of light-driven proton transport by bacteriorhodopsin (bR). PM fragments were also adsorbed on a mercury-supported triethyleneoxythiol (TET) monolayer. On both monolayers, the light-on current exhibits a finite, potential dependent stationary component that decreases linearly with a positive shift in the applied potential. The light-on and light-off capacitive photocurrents were interpreted on the basis of a simple equivalent circuit, which accounts for the potential dependence of the stationary light-on current. The potential of zero stationary current is about equal to +0.010 V vs. saturated calomel electrode (SCE) on DOPC-coated mercury. The absolute potential difference across the PM fragments adsorbed at this applied potential was estimated on the basis of extrathermodynamic considerations and amounts to about +260 mV; it compares favorably with the value, +250 mV, of the transmembrane potential of zero stationary current across an oocyte plasma membrane incorporating bR [Biophys. J. 74 (1998) 403.]. The effect of the proton pumping activity of photoexcited PM fragments on the electroreduction kinetics of ubiquinone-10 incorporated in the DOPC monolayer underlying the PM fragments was investigated.

  5. Enzymatic grafting of carboxyl groups on to chitosan--to confer on chitosan the property of a cationic dye adsorbent.

    PubMed

    Chao, An-Chong; Shyu, Shin-Shing; Lin, Yu-Chuang; Mi, Fwu-Long

    2004-01-01

    Chitosan (CTS) is a good adsorbent for dyes but lacks the ability to adsorb cationic dyes. In this study, chitosan was modified to possess the ability to adsorb cationic dyes from water. Four kinds of phenol derivatives: 4-hydroxybenzoic acid (BA), 3,4-dihydroxybenzoic acid (DBA), 3,4-dihydroxyphenyl-acetic acid (PA), hydrocaffeic acid (CA) were used individually as substrates of tyrosinase to graft onto chitosan. FTIR analysis provided supporting evidence of phenol derivatives being grafted. The grafting amounts of these phenol derivatives onto chitosan were examined by the adsorption of an anionic dye (amaranth) and reached a plateau value. The final contents of carboxyl groups in chitosan (mmol carboxyl groups per kg chitosan) were measured as 46.36 for BA, 70.32 for DBA, 106.44 for PA, and 113.15 for CA. These modified chitosans were used in experiments on uptake of the cationic dyes crystal violet (CV) and bismarck brown Y (BB) by a batch adsorption technique at pH 7 for CV and at pH 9 for BB and 30 degrees C. Langmuir type adsorption was found, and the maximum adsorption capacities for both dyes were increased with the following order CTS-CA>CTS-PA>CTS-DBA>CTS-BA.

  6. Microwave-assisted activated carbon from cocoa shell as adsorbent for removal of sodium diclofenac and nimesulide from aqueous effluents.

    PubMed

    Saucier, Caroline; Adebayo, Matthew A; Lima, Eder C; Cataluña, Renato; Thue, Pascal S; Prola, Lizie D T; Puchana-Rosero, M J; Machado, Fernando M; Pavan, Flavio A; Dotto, G L

    2015-05-30

    Microwave-induced chemical activation process was used to prepare an activated carbon from cocoa shell for efficient removal of two anti-inflammatories, sodium diclofenac (DFC) and nimesulide (NM), from aqueous solutions. A paste was obtained from a mixture of cocoa shell and inorganic components; with a ratio of inorganic: organic of 1 (CSC-1.0). The mixture was pyrolyzed in a microwave oven in less than 10 min. The CSC-1.0 was acidified with a 6 mol L(-1) HCl under reflux to produce MWCS-1.0. The CSC-1.0 and MWCS-1.0 were characterized using FTIR, SEM, N2 adsorption/desorption curves, X-ray diffraction, and point of zero charge (pHpzc). Experimental variables such as initial pH of the adsorbate solutions and contact time were optimized for adsorptive characteristics of MWCS-1.0. The optimum pH for removal of anti-inflammatories ranged between 7.0 and 8.0. The kinetic of adsorption was investigated using general order, pseudo first-order and pseu do-second order kinetic models. The maximum amounts of DCF and NM adsorbed onto MWCS-1.0 at 25 °C are 63.47 and 74.81 mg g(-1), respectively. The adsorbent was tested on two simulated hospital effluents. MWCS-1.0 is capable of efficient removal of DCF and NM from a medium that contains high sugar and salt concentrations.

  7. 46 CFR 308.303 - Amounts insured under interim binder.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... INSURANCE Second Seamen's War Risk Insurance § 308.303 Amounts insured under interim binder. The amounts insured are the amounts specified in the Second Seamen's War Risk Policy (1955) or as modified by...

  8. 46 CFR 308.303 - Amounts insured under interim binder.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... INSURANCE Second Seamen's War Risk Insurance § 308.303 Amounts insured under interim binder. The amounts insured are the amounts specified in the Second Seamen's War Risk Policy (1955) or as modified by...

  9. 46 CFR 308.303 - Amounts insured under interim binder.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... INSURANCE Second Seamen's War Risk Insurance § 308.303 Amounts insured under interim binder. The amounts insured are the amounts specified in the Second Seamen's War Risk Policy (1955) or as modified by...

  10. 46 CFR 308.303 - Amounts insured under interim binder.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... INSURANCE Second Seamen's War Risk Insurance § 308.303 Amounts insured under interim binder. The amounts insured are the amounts specified in the Second Seamen's War Risk Policy (1955) or as modified by...

  11. Removal of acutely hazardous pharmaceuticals from water using multi-template imprinted polymer adsorbent.

    PubMed

    Venkatesh, Avinash; Chopra, Nikita; Krupadam, Reddithota J

    2014-05-01

    Molecularly imprinted polymer adsorbent has been prepared to remove a group of recalcitrant and acutely hazardous (p-type) chemicals from water and wastewaters. The polymer adsorbent exhibited twofold higher adsorption capacity than the commercially used polystyrene divinylbenzene resin (XAD) and powdered activated carbon adsorbents. Higher adsorption capacity of the polymer adsorbent was explained on the basis of high specific surface area formed during molecular imprinting process. Freundlich isotherms drawn showed that the adsorption of p-type chemicals onto polymer adsorbent was kinetically faster than the other reference adsorbents. Matrix effect on adsorption of p-type chemicals was minimal, and also polymer adsorbent was amenable to regeneration by washing with water/methanol (3:1, v/v) solution. The polymer adsorbent was unaltered in its adsorption capacity up to 10 cycles of adsorption and desorption, which will be more desirable in cost reduction of treatment compared with single-time-use activated carbon.

  12. Novel recyclable adsorbent for the removal of copper(II) and lead(II) from aqueous solution.

    PubMed

    Niu, Yaolan; Li, Kan; Ying, Diwen; Wang, Yalin; Jia, Jinping

    2017-04-01

    Adsorbents synthesized with biopolymer have been widely used in the removal of toxic metal ions. Novel high-efficiency, recyclable, and low-cost adsorbents have received more and more attention. Chitosan and cellulose are the most abundant biopolymers in nature. Composite modified adsorbent (CSTEC) was synthesized as novel fibrous materials for the adsorption of Cu(2+) and Pb(2+) ions from water in this study. The functional fiber was characterized to investigate the surface appearance, functional groups, crystallinity, and thermal stability. The kinetics study revealed that adsorption processes of Cu(2+) and Pb(2+) ions on the CSTEC followed the second-order kinetics model. CSTEC showed better performance (Cu(2+), 95.24; Pb(2+), 144.93mgg(-1)) than most of other adsorbents. The co-existing ions (K(+), Na(+), Mg(2+)) had no significant influence on the removal of target ions by the CSTEC. The excellent reusability indicated that CSTEC had the promising application in the treatment of toxic metal pollution.

  13. The profile of adsorbed plasma and serum proteins on methacrylic acid copolymer beads: Effect on complement activation.

    PubMed

    Wells, Laura A; Guo, Hongbo; Emili, Andrew; Sefton, Michael V

    2017-02-01

    Polymer beads made of 45% methacrylic acid co methyl methacrylate (MAA beads) promote vascular regenerative responses in contrast to control materials without methacrylic acid (here polymethyl methacrylate beads, PMMA). In vitro and in vivo studies suggest that MAA copolymers induce differences in macrophage phenotype and polarization and inflammatory responses, presumably due to protein adsorption differences between the beads. To explore differences in protein adsorption in an unbiased manner, we used high resolution shotgun mass spectrometry to identify and compare proteins that adsorb from human plasma or serum onto MAA and PMMA beads. From plasma, MAA beads adsorbed many complement proteins, such as C1q, C4-related proteins and the complement inhibitor factor H, while PMMA adsorbed proteins, such as albumin, C3 and apolipoproteins. Because of the differences in complement protein adsorption, follow-up studies focused on using ELISA to assess complement activation. When incubated in serum, MAA beads generated significantly lower levels of soluble C5b9 and C3a/C3adesarg in comparison to PMMA beads, indicating a decrease in complement activation with MAA beads. The differences in adsorbed protein on the two materials likely alter subsequent cell-material interactions that ultimately result in different host responses and local vascularization.

  14. Enhancement mechanisms behind exclusive removal and selective recovery of copper from salt solutions with an aminothiazole-functionalized adsorbent.

    PubMed

    Xu, Chao; Liu, Fu-Qiang; Gao, Jie; Li, Lan-Juan; Bai, Zhi-Ping; Ling, Chen; Zhu, Chang-Qing; Chen, Da; Li, Ai-Min

    2014-09-15

    The aminothiazole-functionalized adsorbent (CEAD) could exclusively remove and to selectively recover copper. The adsorption and separation properties of Cu(II) onto CEAD from aqueous media, with or without salts such as NaNO3, Ca(NO3)2 and Ni(NO3)2, were systematically compared by carrying out single, binary and multiple component static and dynamic experiments. In binary systems, the adsorption capacities of Cu(II) were obviously increased by 39.47%, 47.37% and 57.89% with Ni(NO3)2, NaNO3 and Ca(NO3)2, respectively. Besides, simulation study was performed to selectively recover Cu(II) from multi-component aqueous media, with the separation factor of only 54.91 in aqueous media without salts. The separation factor became infinite in the presence of NaNO3 and the enhancement ratio for Cu(II) was raised by 126.31%. Dynamic adsorption could separate Cu(II) and Ni(II) completely and the amount of effluent for pure Ni(II) increased to 127 BV with the help of NaNO3. In the predominant chelating mode simulated by density functional theory calculation, a metal ion coordinated with three nitrogen atoms and formed a chelating complex with two five-membered rings, and Cu(II) showed stronger coordinating ability than Ni(II) did. Meanwhile, anions exerted significant beneficial effects by electrostatic screening, and thus strengthened the exclusive removal and selective recovery of Cu(II).

  15. Cremophor EL releases cyclosporin A adsorbed on blood cells and blood vessels, and increases apparent plasma concentration of cyclosporin A.

    PubMed

    Jin, Mingji; Shimada, Tsutomu; Yokogawa, Koichi; Nomura, Masaaki; Mizuhara, Yasuharu; Furukawa, Hiroyuki; Ishizaki, Junko; Miyamoto, Ken-Ichi

    2005-04-11

    We examined the influence of cremophor EL (crEL) on the disposition kinetics of CyA in rats. A dose of 10mg/kg of CyA in a volume of 750 microL containing 4.3, 16 or 30% concentration of crEL was intravenously administered over 1 min to rats. The values of distribution volume at the steady-state (Vd(ss)) and total clearance (CL(tot)) of CyA in the presence of increasing amounts of crEL were decreased to about 1/3-1/5 of those with 4.3% crEL, in a crEL concentration-dependent manner. The values of blood to plasma concentration ratio (RBP) and the apparent tissue to plasma concentration ratio (K(p,app)) of CyA with 30% crEL were both only about 1/2 of those of CyA with 4.3% crEL. Next, rats were intravenously given 30% crEL solution at 30 min after an intravenous administration of CyA (10 mg/kg) with 4.3% crEL. Subsequently, the blood and plasma concentrations of CyA rose significantly to 2.4 and 4.7 times those seen when i.v. 30% crEL was not given, respectively. In an in vitro study, we found that the uptake of CyA by red blood cells is inhibited by crEL, and that CyA adsorbed on the inner surface of blood vessels after the administration of CyA is released by crEL. The disposition kinetics of CyA is altered by i.v. administration in combination with the surfactant vehicle crEL, in a crEL concentration-dependent manner.

  16. Adsorbed molecules in external fields: Effect of confining potential

    NASA Astrophysics Data System (ADS)

    Tyagi, Ashish; Silotia, Poonam; Maan, Anjali; Prasad, Vinod

    2016-12-01

    We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials.

  17. Candidate Source of Flux Noise in SQUIDs: Adsorbed Oxygen Molecules

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Shi, Chuntai; Hu, Jun; Han, Sungho; Yu, Clare C.; Wu, R. Q.

    2015-08-01

    A major obstacle to using superconducting quantum interference devices (SQUIDs) as qubits is flux noise. We propose that the heretofore mysterious spins producing flux noise could be O2 molecules adsorbed on the surface. Using density functional theory calculations, we find that an O2 molecule adsorbed on an α-alumina surface has a magnetic moment of ˜1.8 μB . The spin is oriented perpendicular to the axis of the O-O bond, the barrier to spin rotations is about 10 mK. Monte Carlo simulations of ferromagnetically coupled, anisotropic X Y spins on a square lattice find 1 /f magnetization noise, consistent with flux noise in Al SQUIDs.

  18. Palladium dimers adsorbed on graphene: A DFT study

    NASA Astrophysics Data System (ADS)

    Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

    2015-05-01

    The 2D structure of graphene shows a great promise for enhanced catalytic activity when adsorbed with palladium. We performed a systematic density functional theory (DFT) study of the adsorption of palladium dimer (Pd2) on graphene using SIESTA package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Pd2-graphene system are calculated. Both horizontal and vertical orientations of Pd2 on graphene are studied. Our calculations revealed that the minimum energy configuration for Pd dimer is parallel to the graphene sheet with its two atoms occupying centre of adjacent hexagonal rings of graphene sheet. Magnetic moment is induced for Pd dimer adsorbed on graphene in vertical orientation while horizontal orientation of Pd dimer on graphene do not exhibit magnetism. Insignificant energy differences among adsorption sites means that dimer mobility on the graphene sheet is high. There is imperceptible distortion of graphene sheet perpendicular to its plane. However, some lateral displacements are seen.

  19. Nanoalloy electrocatalysis: Simulating cyclic voltammetry from configurational thermodynamics with adsorbates

    SciTech Connect

    Wang, Lin -Lin; Tan, Teck L.; Johnson, Duane D.

    2015-02-27

    We simulate the adsorption isotherms for alloyed nanoparticles (nanoalloys) with adsorbates to determine cyclic voltammetry (CV) during electrocatalysis. The effect of alloying on nanoparticle adsorption isotherms is provided by a hybrid-ensemble Monte Carlo simulation that uses the cluster expansion method extended to non-exchangeable coupled lattices for nanoalloys with adsorbates. Exemplified here for the hydrogen evolution reaction, a 2-dimensional CV is mapped for Pd–Pt nanoalloys as a function of both electrochemical potential and the global Pt composition, and shows a highly non-linear alloying effect on CV. Detailed features in CV arise from the interplay among the H-adsorption in multiple sites that is closely correlated with alloy configurations, which are in turn affected by the H-coverage. The origins of specific features in CV curves are assigned. As a result, the method provides a more complete means to design nanoalloys for electrocatalysis.

  20. Nanoalloy electrocatalysis: Simulating cyclic voltammetry from configurational thermodynamics with adsorbates

    DOE PAGES

    Wang, Lin -Lin; Tan, Teck L.; Johnson, Duane D.

    2015-02-27

    We simulate the adsorption isotherms for alloyed nanoparticles (nanoalloys) with adsorbates to determine cyclic voltammetry (CV) during electrocatalysis. The effect of alloying on nanoparticle adsorption isotherms is provided by a hybrid-ensemble Monte Carlo simulation that uses the cluster expansion method extended to non-exchangeable coupled lattices for nanoalloys with adsorbates. Exemplified here for the hydrogen evolution reaction, a 2-dimensional CV is mapped for Pd–Pt nanoalloys as a function of both electrochemical potential and the global Pt composition, and shows a highly non-linear alloying effect on CV. Detailed features in CV arise from the interplay among the H-adsorption in multiple sites thatmore » is closely correlated with alloy configurations, which are in turn affected by the H-coverage. The origins of specific features in CV curves are assigned. As a result, the method provides a more complete means to design nanoalloys for electrocatalysis.« less

  1. Nanoalloy electrocatalysis: simulating cyclic voltammetry from configurational thermodynamics with adsorbates.

    PubMed

    Wang, Lin-Lin; Tan, Teck L; Johnson, Duane D

    2015-11-14

    We simulate the adsorption isotherms for alloyed nanoparticles (nanoalloys) with adsorbates to determine cyclic voltammetry (CV) during electrocatalysis. The effect of alloying on nanoparticle adsorption isotherms is provided by a hybrid-ensemble Monte Carlo simulation that uses the cluster expansion method extended to non-exchangeable coupled lattices for nanoalloys with adsorbates. Exemplified here for the hydrogen evolution reaction, a 2-dimensional CV is mapped for Pd-Pt nanoalloys as a function of both electrochemical potential and the global Pt composition, and shows a highly non-linear alloying effect on CV. Detailed features in CV arise from the interplay among the H-adsorption in multiple sites that is closely correlated with alloy configurations, which are in turn affected by the H-coverage. The origins of specific features in CV curves are assigned. The method provides a more complete means to design nanoalloys for electrocatalysis.

  2. Radiolysis of alanine adsorbed in a clay mineral

    SciTech Connect

    Aguilar-Ovando, Ellen Y.; Negron-Mendoza, Alicia

    2013-07-03

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically {gamma}-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.

  3. Monte Carlo lattice models for adsorbed polymer conformation

    NASA Technical Reports Server (NTRS)

    Good, B. S.

    1985-01-01

    The adhesion between a polymer film and a metal surface is of great technological interest. However, the prediction of adhesion and wear properties of polymer coated metals is quite difficult because a fundamental understanding of the polymer surface interaction does not yet exist. A computer model for the conformation of a polymer molecule adsorbed on a surface is discussed. The chain conformation is assumed to be described by a partially directed random walk on a three dimensional simple cubic lattice. An attractive surface potential is incorporated into the model through the use of a random walk step probability distribution that is anisotropic in the direction normal to the attractive surface. The effects of variations in potential characteristics are qualitatively included by varying both the degree of anisotropy of the step distribution and the range of the anisotropy. Polymer conformation is characterized by the average end to end distance, average radius of gyration, and average number of chain segments adsorbed on the surface.

  4. Allantoin as a solid phase adsorbent for removing endotoxins.

    PubMed

    Vagenende, Vincent; Ching, Tim-Jang; Chua, Rui-Jing; Gagnon, Pete

    2013-10-04

    In this study we present a simple and robust method for removing endotoxins from protein solutions by using crystals of the small-molecule compound 2,5-dioxo-4-imidazolidinyl urea (allantoin) as a solid phase adsorbent. Allantoin crystalline powder is added to a protein solution at supersaturated concentrations, endotoxins bind and undissolved allantoin crystals with bound endotoxins are removed by filtration or centrifugation. This method removes an average of 99.98% endotoxin for 20 test proteins. The average protein recovery is ∼80%. Endotoxin binding is largely independent of pH, conductivity, reducing agent and various organic solvents. This is consistent with a hydrogen-bond based binding mechanism. Allantoin does not affect protein activity and stability, and the use of allantoin as a solid phase adsorbent provides better endotoxin removal than anion exchange, polymixin affinity and biological affinity methods for endotoxin clearance.

  5. Graphene-modulated photo-absorption in adsorbed azobenzene monolayers.

    PubMed

    Fu, Qiang; Cocchi, Caterina; Nabok, Dmitrii; Gulans, Andris; Draxl, Claudia

    2017-02-22

    The impact of graphene on the photo-absorption properties of trans- and cis-azobenzene monolayers is studied in the framework of density-functional theory and many-body perturbation theory. We find that, despite the weak hybridization between the electronic bands of graphene and those of the azobenzene monolayers, graphene remarkably modulates the absorption spectra of the adsorbates. The excitation energies are affected via two counteracting mechanisms: substrate polarization reduces the band-gap of azobenzene, and enhanced dielectric screening weakens the attractive interaction between electrons and holes. The competition between these two effects gives rise to an overall blueshift of peaks stemming from intramolecular excitations, and a redshift of peaks from intermolecular ones. Even more interesting is that excitations corresponding to intermolecular electron-hole pairs, which are dark in the isolated monolayers, are activated by the graphene substrate. Our results demonstrate that the photoisomerization process of weakly adsorbed azobenzene undergoes notable changes on a carbon-based substrate.

  6. Adsorption of trichlorophenol on zeolite and adsorbent regeneration with ozone.

    PubMed

    Zhang, Yongjun; Mancke, Raoul Georg; Sabelfeld, Marina; Geißen, Sven-Uwe

    2014-04-30

    A FAU-type zeolite was studied as an adsorbent to remove 2,4,6-trichlorophenol (TCP), a frequently detected recalcitrant pollutant in water bodies. Both adsorption isotherm and kinetics were studied with TCP concentrations from 10 to 100mg/L. It was observed that TCP was effectively adsorbed onto the zeolite with a high adsorption capacity and a high kinetic rate. Freundlich model and pseudo-second-order kinetics were successfully applied to describe the experimental data. The influence of solution pH was also studied. Furthermore, ozone was applied to regenerate the loaded zeolite. It was found that an effective adsorption of TCP was kept for at least 8 cycles of adsorption and regeneration. The ozonation also increased the BET specific surface of zeolite by over 60% and consequently enhanced the adsorption capacity.

  7. pyIAST: Ideal adsorbed solution theory (IAST) Python package

    NASA Astrophysics Data System (ADS)

    Simon, Cory M.; Smit, Berend; Haranczyk, Maciej

    2016-03-01

    Ideal adsorbed solution theory (IAST) is a widely-used thermodynamic framework to readily predict mixed-gas adsorption isotherms from a set of pure-component adsorption isotherms. We present an open-source, user-friendly Python package, pyIAST, to perform IAST calculations for an arbitrary number of components. pyIAST supports several common analytical models to characterize the pure-component isotherms from experimental or simulated data. Alternatively, pyIAST can use numerical quadrature to compute the spreading pressure for IAST calculations by interpolating the pure-component isotherm data. pyIAST can also perform reverse IAST calculations, where one seeks the required gas phase composition to yield a desired adsorbed phase composition.

  8. Heavy metals and adsorbents effects on activated sludge microorganisms.

    PubMed

    Ong, S A; Lim, P E; Seng, C E

    2004-01-01

    The sorption of Cu(II) and Cd(II) from synthetic solution by powdered activated carbon (PAC), biomass, rice husk (RH) and activated rice husk (ARH) were investigate under batch conditions. After activated by concentrated nitric acid for 15 hours at 60-65 degrees C, the adsorption capacity for RH was increased. The adsorbents arranged in the increasing order of adsorption capacities to the Langmuir Q degree parameter were biomass > PAC > ARH > RH. The addition of adsorbents in base mix solution had increased the specific oxygen uptake rate (SOUR) activated sludge microorganisms with and without the presence of metals. The increased of SOUR were due to the ability of PAC and RH in reducing the inhibitory effect of metals on microorganisms and provide a reaction site between activated sludge microorganisms and substrates.

  9. Development of glucose sensor using two-photon adsorbed photopolymerization.

    PubMed

    Kim, Jong Min; Park, Jung-Jin; Lee, Haeng-Ja; Kim, Woo-Sik; Muramatsu, Hiroshi; Chang, Sang-Mok

    2010-01-01

    A novel glucose sensor was constructed, and its analytical potential examined. A chip-type three-electrode system for use in a flow-type electrochemical glucose sensor was fabricated using a UV lithography technique on a glass slide. An Ag/AgCl reference electrode was made by electroplating silver onto a Pt electrode and dipping in a saturated KCl solution for 30 min. In addition, a glucose-sensing electrode was fabricated using a two-photon adsorbed photopolymerization technique with a photo-reactive resin containing a glucose oxidase enzyme, ferrocene mediator, non-ionic surfactant, and carbon nanotubes. The cyclic voltammetry of the potassium ferrocyanide in the Pt sensor system showed a stable electrode condition. The response of the modified Pt sensor confirms the feasibility of using a two-photon adsorbed photopolymerization technique for the easy fabrication of functional biosensors.

  10. Adsorbed molecules in external fields: Effect of confining potential.

    PubMed

    Tyagi, Ashish; Silotia, Poonam; Maan, Anjali; Prasad, Vinod

    2016-12-05

    We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials.

  11. An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

    EPA Science Inventory

    Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO3)2•6H2O functionalization of zeolite. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The adsorption capacity of the adsorbents at 21...

  12. Development of the Molecular Adsorber Coating for Spacecraft and Instrument Interiors

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin

    2011-01-01

    On-orbit Molecular Contamination occurs when materials outgas and deposit onto very sensitive interior surfaces of the spacecraft and instruments. The current solution, Molecular Adsorber Pucks, has disadvantages, which are reviewed. A new innovative solution, Molecular Adsorber Coating (MAC), is currently being formulated, optimized, and tested. It is a sprayable alternative composed of Zeolite-based coating with adsorbing properties.

  13. Silver diffusion over silicon surfaces with adsorbed tin atoms

    SciTech Connect

    Dolbak, A. E. Olshanetskii, B. Z.

    2015-02-15

    Silver diffusion over the (111), (100), and (110) surfaces of silicon with preliminarily adsorbed tin atoms is studied by Auger electron spectroscopy and low-energy electron diffraction. Diffusion is observed only on the surface of Si(111)-2√3 × 2√3-Sn. The diffusion mechanism is established. It is found that the diffusion coefficient depends on the concentration of diffusing atoms. The diffusion coefficient decreases with increasing silver concentration, while the activation energy and the preexponential factor increase.

  14. Toxicity of Uranium Adsorbent Materials using the Microtox Toxicity Test

    SciTech Connect

    Park, Jiyeon; Jeters, Robert T.; Gill, Gary A.; Kuo, Li-Jung; Bonheyo, George T.

    2015-10-01

    The Marine Sciences Laboratory at the Pacific Northwest National Laboratory evaluated the toxicity of a diverse range of natural and synthetic materials used to extract uranium from seawater. The uranium adsorbent materials are being developed as part of the U. S. Department of Energy, Office of Nuclear Energy, Fuel Resources Program. The goal of this effort was to identify whether deployment of a farm of these materials into the marine environment would have any toxic effects on marine organisms.

  15. Resonant vibrational excitation of adsorbed molecules by electron impact

    NASA Astrophysics Data System (ADS)

    Djamo, V.; Teillet-Billy, D.; Gauyacq, J. P.

    1993-11-01

    The vibrational excitation of N2 molecules adsorbed on a silver surface by low energy electron impact is studied within the newly developed coupled angular mode method. The process involves the formation of a transient negative molecular ion. The results account well for the observations of Demuth and co-workers. They also reveal that most of the vibrational excitation corresponds to electrons scattered into the metal and thus unobservable in a scattering experiment.

  16. Second virial coefficient of helium adsorbed on liquid hydrogen

    SciTech Connect

    Paine, C.G.; Seidel, G.M. )

    1994-08-01

    The nonlinear dependence of the surface energy of liquid hydrogen as a function of the density of helium gas in equilibrium with the liquid surface has been used to determine the second virial coefficient of the two-dimensional gas of helium atoms adsorbed on the surface. The surface energy of both liquid hydrogen and liquid deuterium has been measured in the presence of [sup 4]He and [sup 3]He. The experimental results are in rough agreement with theoretical prediction.

  17. Non-linear optical studies of adsorbates: Spectroscopy and dynamics

    SciTech Connect

    Zhu, Xiangdong.

    1989-08-01

    In the first part of this thesis, we have established a systematic procedure to apply the surface optical second-harmonic generation (SHG) technique to study surface dynamics of adsorbates. In particular, we have developed a novel technique for studies of molecular surface diffusions. In this technique, the laser-induced desorption with two interfering laser beams is used to produce a monolayer grating of adsorbates. The monolayer grating is detected with diffractions of optical SHG. By monitoring the first-order second-harmonic diffraction, we can follow the time evolution of the grating modulation from which we are able to deduce the diffusion constant of the adsorbates on the surface. We have successfully applied this technique to investigate the surface diffusion of CO on Ni(111). The unique advantages of this novel technique will enable us to readily study anisotropy of a surface diffusion with variable grating orientation, and to investigate diffusion processes of a large dynamic range with variable grating spacings. In the second part of this work, we demonstrate that optical infrared-visible sum-frequency generation (SFG) from surfaces can be used as a viable surface vibrational spectroscopic technique. We have successfully recorded the first vibrational spectrum of a monolayer of adsorbates using optical infrared-visible SFG. The qualitative and quantitative correlation of optical SFG with infrared absorption and Raman scattering spectroscopies are examined and experimentally demonstrated. We have further investigated the possibility to use transient infrared-visible SFG to probe vibrational transients and ultrafast relaxations on surfaces. 146 refs.

  18. Heterogeneous Ozonolysis of Surface Adsorbed Lignin Pyrolysis Products

    NASA Astrophysics Data System (ADS)

    Hinrichs, R. Z.

    2012-12-01

    Biomass combustion releases semi-volatile organic compounds into the troposphere, including many phenols and methoxyphenols as the result of lignin pyrolysis. Given their relatively low vapor pressures, these compounds readily adsorb on inorganic and organic aerosol substrates where they may alter aerosol properties and undergo heterogeneous chemistry. We use infrared spectroscopy (DRIFTS and ATR-FTIR) to monitor the adsorption and subsequent heterogeneous ozonolysis of model lignin pyrolysis products, including catechol, eugenol, and 4-propylguaiacol. Ozonolysis reaction kinetics were compared on various inorganic substrates - such as Al2O3 and NaCl, which serve as mineral and sea salt aerosol substrates, respectively - and as a function of ozone concentration and relative humidity. Following in situ FTIR analysis, the adsorbed organics were extracted and analyzed using gas chromatography-mass spectroscopy to identify reaction products and quantify product branching ratios. Ozonolysis of catechol and 4-propylguaiacol readily resulted in ring cleavage forming dicarboxylic acids (e.g., muconic acid). Eugenol ozonolysis proceeded rapidly at the alkene side chain producing homovanillic acid and homovanillin in an approximate 2:1 branching ratio at 0% RH; ring cleavage was also observed. For all lignin pyrolysis products, heterogeneous ozonolysis was faster on NaCl versus Al2O3. Implications for the atmospheric chemistry of semi-volatile methoxylphenols adsorbed on aerosol substrates will be discussed.

  19. Modeling adsorbate-induced property changes of carbon nanotubes.

    PubMed

    Groß, Lynn; Bahlke, Marc Philipp; Steenbock, Torben; Klinke, Christian; Herrmann, Carmen

    2017-05-05

    Because of their potential for chemical functionalization, carbon nanotubes (CNTs) are promising candidates for the development of devices such as nanoscale sensors or transistors with novel gating mechanisms. However, the mechanisms underlying the property changes due to functionalization of CNTs still remain subject to debate. Our goal is to reliably model one possible mechanism for such chemical gating: adsorption directly on the nanotubes. Within a Kohn-Sham density functional theory framework, such systems would ideally be described using periodic boundary conditions. Truncating the tube and saturating the edges in practice often offers a broader selection of approximate exchange-correlation functionals and analysis methods. By comparing the two approaches systematically for NH3 and NO2 adsorbates on semiconducting and metallic CNTs, we find that while structural properties are less sensitive to the details of the model, local properties of the adsorbate may be as sensitive to truncation as they are to the choice of exchange-correlation functional, and are similarly challenging to compute as adsorption energies. This suggests that these adsorbate effects are nonlocal. © 2017 Wiley Periodicals, Inc.

  20. SPR-MS: from identifying adsorbed molecules to image tissues

    NASA Astrophysics Data System (ADS)

    Masson, Jean-François; Breault-Turcot, Julien; Forest, Simon; Chaurand, Pierre

    2015-03-01

    Surface plasmon resonance (SPR) sensors have become valuable analytical sensors for biomolecule detection. While SPR is heralded with high sensitivity, label-free and real-time detection, nonspecific adsorption and detection of ultralow concentrations remain issues. Nonspecific adsorption can be minimized using adequate surface chemistry. For example, we have employed peptide monolayers to reduce nonspecific adsorption of crude serum or cell lysate. It is important to uncover the nature of molecules nonspecifically adsorbing to surfaces in these biofluids, to further improve understanding of the nonspecific adsorption processes. Mass spectrometry (MS) provides a complementary tool to SPR to identify biomolecule adsorbed to surface. Trypsic digestion of the proteins adsorbed to surfaces led to identification of characteristic peptides from the proteins involved in nonspecific adsorption. Nonspecific adsorption in crude cell lysate results mainly from lipids, as confirmed with SPR and MS but proteins were observed on some surfaces. In another application of SPR and MS, imaging SPR can be used in combination to imaging MS to image tissue sections. Thin sections of mouse liver were inserted in the fluidic chamber of a SPRi instrument and proteins were transferred to the SPRi chip. The SPR chip was then imaged using MALDI imaging MS to identify the biomolecules that were transferred to the SPRi chip.

  1. Structural damages in adsorbed vaccines affected by freezing.

    PubMed

    Kurzątkowski, Wiesław; Kartoğlu, Ümit; Staniszewska, Monika; Górska, Paulina; Krause, Aleksandra; Wysocki, Mirosław Jan

    2013-03-01

    This study was planned to evaluate structural damages in adsorbed vaccines affected by freezing using scanning electron microscopy and X-ray analysis of the elements. Randomly selected 42 vials of eight different types of WHO pre-qualified adsorbed freeze-sensitive vaccines from 10 manufacturers were included in the study. Vaccines were kept at 5 °C. Selected numbers of vials from each type were then exposed to -25 °C for 24 h periods. All samples were evaluated for their structure using scanning electron microscopy, X-ray analysis of the elements and precipitation time. Scanning electron microscopy of vaccines affected by freezing showed either smooth or rough surfaced conglomerates associated with phosphate content of the precipitate. These vaccines precipitated 2-15 times faster compared to non-frozen samples. Non-frozen samples showed uniform flocculent structure either dense or dispersed. X-ray analysis of precipitates in frozen samples confirmed that the precipitate is mainly aluminium clutters. Scanning electron microscopy confirmed that the lattice structure of bonds between adsorbent and the antigen is broken and aluminium forms conglomerates that grow in size and weight. The precipitation time of vaccines affected by freezing is 4.5 times faster on average compared to non-frozen samples. These facts form the basis of the "shake test".

  2. Metal carbon bond energies for adsorbed hydrocarbons from calorimetric data

    NASA Astrophysics Data System (ADS)

    Gross, Heike; Campbell, Charles T.; King, David A.

    2004-11-01

    Single crystal adsorption calorimetry (SCAC) is a powerful new method for measuring adsorption and reaction energies. Particularly for hydrocarbons, where little or no information is available from either experiment or theory on well-defined surfaces, this method can provide crucially needed information. Assignment of the measured calorimetric heats to the appropriate surface reaction yields directly reaction heats and heats of formation of surface species. An important extension using these results is to derive values for metal-carbon bond energies in adsorbed hydrocarbon species. In this paper we review the definition of the bond dissociation energy for a surface species and discuss methodologies and limitations for calculating accurate values of this quantity from measured calorimetric data. As a step in establishing benchmark data for adsorbed hydrocarbons, we calculate a Pt-C σ bond strength, < D(Pt-C)>, of about 245 kJ/mol from data for ethylidyne on Pt{1 1 1}. Two independent methods, the quasiempirical valence bond (QVB) method and an average bond energy (ABE) method, were used to obtain this value, and the two values derived from these two approaches agree quite well. We also discuss the implications and applicability of this value of D(Pt-C) for other adsorbed hydrocarbons and on other Pt surfaces, and estimates of how this bond energy should differ when the C atom's ligands are different.

  3. Distribution of metal and adsorbed guest species in zeolites

    SciTech Connect

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

  4. Development Trends in Porous Adsorbents for Carbon Capture.

    PubMed

    Sreenivasulu, Bolisetty; Sreedhar, Inkollu; Suresh, Pathi; Raghavan, Kondapuram Vijaya

    2015-11-03

    Accumulation of greenhouse gases especially CO2 in the atmosphere leading to global warming with undesirable climate changes has been a serious global concern. Major power generation in the world is from coal based power plants. Carbon capture through pre- and post- combustion technologies with various technical options like adsorption, absorption, membrane separations, and chemical looping combustion with and without oxygen uncoupling have received considerable attention of researchers, environmentalists and the stake holders. Carbon capture from flue gases can be achieved with micro and meso porous adsorbents. This review covers carbonaceous (organic and metal organic frameworks) and noncarbonaceous (inorganic) porous adsorbents for CO2 adsorption at different process conditions and pore sizes. Focus is also given to noncarbonaceous micro and meso porous adsorbents in chemical looping combustion involving insitu CO2 capture at high temperature (>400 °C). Adsorption mechanisms, material characteristics, and synthesis methods are discussed. Attention is given to isosteric heats and characterization techniques. The options to enhance the techno-economic viability of carbon capture techniques by integrating with CO2 utilization to produce industrially important chemicals like ammonia and urea are analyzed. From the reader's perspective, for different classes of materials, each section has been summarized in the form of tables or figures to get a quick glance of the developments.

  5. Adsorption isotherm of non-azeotropic solution onto porous adsorbents

    NASA Astrophysics Data System (ADS)

    Bono, A.; Ramlan, N. A.; Anisuzzaman, S. M.; Chu, C. M.; Farm, Y. Y.

    2016-06-01

    Adsorption isotherm is essential component in the understanding of the adsorption process. Several methods of the measurements, analysis and interpretation of adsorption from solution have been reported in the literature. Most of the measurements of adsorption isotherm from solution were involved the measurement of excess isotherm conducted at low region of sorbates concentration. Direct interpretation of excess adsorption isotherm as adsorption isotherm is always been practice. Therefore, in this work a study on the measurement of the adsorption isotherm from solution of non-azeotropic organic solvent mixture onto porous adsorbents for whole range of liquid concentration was conducted. The study included the measurement of excess adsorption isotherm using conventional technique. Theoretical analysis and interpretation of adsorption isotherm from the excess isotherm were conducted using Pseudo Ideal Adsorption, Gibbs Dividing Plane Model and Langmuir-Fruendlich binary isotherm model. For organic solvents, acetone and propanol were chosen as the adsorbates due to the non-azeotropic properties in the mixture. Activated carbon and silicalite were chosen as adsorbents due to the different in their porosity such as macro porous and micro porous structure. The result of the study has revealed that the adsorption isotherm of non-azeotropic mixture onto activated carbon and silicalite can be interpreted as monolayer type of adsorption.

  6. Use of sepiolite as an adsorbent for the removal of copper (II) from industrial waste leachate

    NASA Astrophysics Data System (ADS)

    Gamze Turan, N.; Ardali, Yüksel

    2013-04-01

    as talc, but it has discontinuities and inversion of the silica sheets, which give rise to structural tunnels and blocks. In the inner blocks, all corners of the silica tetrahedral are connected to adjacent blocks, but in the outer blocks, some of the corners are Si atoms bound to hydroxyls (Si-OH). This unique structure allows the penetration of organic and inorganic species into the structure and assigns sepiolite an industrial importance in adsorption. The objective of the present study is to investigate the feasibility of using sepiolite for the adsorptive removal of Cu (II) from the industrial waste leachate. The adsorption capacities and sorption efficiencies are determined. The pseudo first order, the pseudo-second order, Elovich and the intra particle diffusion kinetic models are used to describe the kinetic data to estimate the rate constants. The adsorption of Cu (II) from the aqueous leachate of industrial wastes onto sepiolite was performed using a batch equilibrium technique. At first stage, one-factor-at-a-time experiments were performed to see the individual effects of initial pH, adsorbent dosage and contact time. The adsorption of Cu (II) was favorably influenced by an increase in the adsorbent dosage. The maximum percent removal of Cu (II) were observed at pH>6, and significantly decreased at lower pH value. The optimum contact time is found as 10 min. for the removal of Cu (II). The increment in contact time from 10 min. to 120 min. did not show a significant effect on efficiency. The maximum Cu (II) adsorption efficiencies were obtained at 94.45%. The pseudo second order kinetic model agrees very well with the dynamical behavior for the adsorption of Cu (II) from aqueous leachate of industrial waste onto sepiolite. The results indicate that the use of sepiolite that is locally available and almost free of cost as an adsorbent could be a viable alternative to activated carbon for the removal of Cu (II) ions from aqueous solutions.

  7. Effects of harvesting date and storage on the amounts of polyacetylenes in carrots, Daucus carota.

    PubMed

    Kjellenberg, Lars; Johansson, Eva; Gustavsson, Karl-Erik; Olsson, Marie E

    2010-11-24

    The amounts of three main polyacetylenes in carrots; falcarinol, falcarindiol, and falcarindiol-3-acetate, were determined by HPLC, during three seasons, in carrots harvested several times per season and at different locations in Sweden. The amounts of falcarindiol first decreased from a relatively high level and then increased later in the harvest season. The amounts of falcarindiol-3-acetate showed similar variations, whereas the amounts of falcarinol did not exhibit any significant variation during the harvest season. During storage the amount of polyacetylenes leveled off, increasing in samples initially low and decreasing in samples initially high in polyacetylenes. The amounts of all polyacetylenes varied significantly due to external factors and between stored and fresh samples. This variation opens up possibilities to achieve a chemical composition of polyacetylenes at harvest that minimizes the risk of bitter off-taste and maximizes the positive health effects reported in connection with polyacetylenes in carrots.

  8. 5 CFR 870.202 - Basic insurance amount (BIA).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 2 2013-01-01 2013-01-01 false Basic insurance amount (BIA). 870.202... REGULATIONS (CONTINUED) FEDERAL EMPLOYEES' GROUP LIFE INSURANCE PROGRAM Types and Amount of Insurance § 870.202 Basic insurance amount (BIA). (a)(1) An employee's Basic insurance amount (BIA) is either: (i)...

  9. 5 CFR 870.202 - Basic insurance amount (BIA).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Basic insurance amount (BIA). 870.202... REGULATIONS (CONTINUED) FEDERAL EMPLOYEES' GROUP LIFE INSURANCE PROGRAM Types and Amount of Insurance § 870.202 Basic insurance amount (BIA). (a)(1) An employee's Basic insurance amount (BIA) is either: (i)...

  10. 48 CFR 28.102-2 - Amount required.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... lesser amount is adequate for the protection of the Government, the penal amount of performance bonds... lesser amount is adequate for the protection of the Government, the penal amount of the payment bond or... secure any needed additional protection by directing the contractor to— (1) Increase the penal sum of...

  11. Interaction of inorganic anions with iron-mineral adsorbents in aqueous media--a review.

    PubMed

    Kumar, Eva; Bhatnagar, Amit; Hogland, William; Marques, Marcia; Sillanpää, Mika

    2014-01-01

    A number of inorganic anions (e.g., nitrate, fluoride, bromate, phosphate, and perchlorate) have been reported in alarming concentrations in numerous drinking water sources around the world. Their presence even in very low concentrations may cause serious environmental and health related problems. Due to the presence and significance of iron minerals in the natural aquatic environment and increasing application of iron in water treatment, the knowledge of the structure of iron and iron minerals and their interactions with aquatic pollutants, especially inorganic anions in water are of great importance. Iron minerals have been known since long as potential adsorbents for the removal of inorganic anions from aqueous phase. The chemistry of iron and iron minerals reactions in water is complex. The adsorption ability of iron and iron minerals towards inorganic anions is influenced by several factors such as, surface characteristics of the adsorbent (surface area, density, pore volume, porosity, pore size distribution, pHpzc, purity), pH of the solution, and ionic strength. Furthermore, the physico-chemical properties of inorganic anions (pore size, ionic radius, bulk diffusion coefficient) also significantly influence the adsorption process. The aim of this paper is to provide an overview of the properties of iron and iron minerals and their reactivity with some important inorganic anionic contaminants present in water. It also summarizes the usage of iron and iron minerals in water treatment technology.

  12. LSPR properties of metal nanoparticles adsorbed at a liquid-liquid interface.

    PubMed

    Yang, Zhilin; Chen, Shu; Fang, Pingping; Ren, Bin; Girault, Hubert H; Tian, Zhongqun

    2013-04-21

    Unlike the solid-air and solid-liquid interfaces, the optical properties of metal nanoparticles adsorbed at the liquid-liquid interface have not been theoretically exploited to date. In this work, the three dimensional finite difference time domain (3D-FDTD) method is employed to clarify the localized surface plasmon resonance (LSPR) based optical properties of gold nanoparticles (NPs) adsorbed at the water-oil interface, including near field distribution, far field absorption and their relevance. The LSPR spectra of NPs located at a liquid-liquid interface are shown to differ significantly from those in a uniform liquid environment or at the other interfaces. The absorption spectra exhibit two distinct LSPR peaks, the positions and relative strengths of which are sensitive to the dielectric properties of each liquid and the exact positions of the NPs with respect to the interface. Precise control of the particles' position and selection of the appropriate wavelength of the excitation laser facilitates the rational design and selective excitation of localized plasmon modes for interfacial NPs, a necessary advance for the exploration of liquid-liquid interfaces via surface enhanced Raman spectroscopy (SERS). According to our calculations, the SERS enhancement factor for Au nanosphere dimers at the water-oil interface can be as high as 10(7)-10(9), implying significant promise for future investigations of interfacial structure and applications of liquid-liquid interfaces towards chemical analysis.

  13. Ceria modified activated carbon: an efficient arsenic removal adsorbent for drinking water purification

    NASA Astrophysics Data System (ADS)

    Sawana, Radha; Somasundar, Yogesh; Iyer, Venkatesh Shankar; Baruwati, Babita

    2016-03-01

    Ceria (CeO2) coated powdered activated carbon was synthesized by a single step chemical process and demonstrated to be a highly efficient adsorbent for the removal of both As(III) and As(V) from water without any pre-oxidation process. The formation of CeO2 on the surface of powdered activated carbon was confirmed by X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The percentage of Ce in the adsorbent was confirmed to be 3.5 % by ICP-OES. The maximum removal capacity for As(III) and As(V) was found to be 10.3 and 12.2 mg/g, respectively. These values are comparable to most of the commercially available adsorbents. 80 % of the removal process was completed within 15 min of contact time in a batch process. More than 95 % removal of both As(III) and As(V) was achieved within an hour. The efficiency of removal was not affected by change in pH (5-9), salinity, hardness, organic (1-4 ppm of humic acid) and inorganic anions (sulphate, nitrate, chloride, bicarbonate and fluoride) excluding phosphate. Presence of 100 ppm phosphate reduced the removal significantly from 90 to 18 %. The equilibrium adsorption pattern of both As(III) and As(V) fitted well with the Freundlich model with R 2 values 0.99 and 0.97, respectively. The material shows reusability greater than three times in a batch process (arsenic concentration reduced below 10 ppb from 330 ppb) and a life of at least 100 L in a column study with 80 g material when tested under natural hard water (TDS 1000 ppm, pH 7.8, hardness 600 ppm as CaCO3) spiked with 330 ppb of arsenic.

  14. A method for preparing ferric activated carbon composites adsorbents to remove arsenic from drinking water.

    PubMed

    Zhang, Qiao Li; Lin, Y C; Chen, X; Gao, Nai Yun

    2007-09-30

    Iron oxide/activated carbon (FeO/AC) composite adsorbent material, which was used to modify the coal-based activated carbon (AC) 12 x 40, was prepared by the special ferric oxide microcrystal in this study. This composite can be used as the adsorbent to remove arsenic from drinking water, and Langmuir isotherm adsorption equation well describes the experimental adsorption isotherms. Then, the arsenic desorption can subsequently be separated from the medium by using a 1% aqueous NaOH solution. The apparent characters and physical chemistry performances of FeO/AC composite were investigated by X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Batch and column adsorption experiments were carried out to investigate and compare the arsenic removal capability of the prepared FeO/AC composite material and virgin activated carbon. It can be concluded that: (1) the main phase present in this composite are magnetite (Fe(3)O(4)), maghemite (gamma-Fe(2)O(3)), hematite (alpha-Fe(2)O(3)) and goethite (alpha-FeO(OH)); (2) the presence of iron oxides did not significantly affect the surface area or the pore structure of the activated carbon; (3) the comparisons between the adsorption isotherms of arsenic from aqueous solution onto the composite and virgin activated carbon showed that the FeO/AC composite behave an excellent capacity of adsorption arsenic than the virgin activated carbon; (4) column adsorption experiments with FeO/AC composite adsorbent showed that the arsenic could be removed to below 0.01 mg/L within 1250 mL empty bed volume when influent concentration was 0.5mg/L.

  15. The heterogeneous interaction of HOCl with solid KBr substrates: the catalytic role of adsorbed halogens.

    PubMed

    Santschi, Ch; Rossi, M J

    2005-07-07

    The heterogeneous reactivity of HOCl on solid KBr at ambient temperature has been studied using a Knudsen flow reactor. On solid KBr steady-state uptake experiments reveal the formation of Br- and Cl-containing reaction products formed in secondary reactions such as Br(2), BrCl, HOBr, BrOCl, Cl(2) and Cl(2)O with the latter two predominating in the late stages of the reaction. The uptake coefficient gamma spanning a range between 0.15 and 1 x 10(-3) and product yields of HOCl strongly depend on the nature of the solid sample, whether grain, ground grain or thin sprayed film, as well as on sample processing such as pumping and/or heating. Furthermore, the presence of adsorbed halogen species such as Br(2)(a) are crucial for the kinetics of the reaction of HOCl with solid KBr substrates. The presence of surface-adsorbed water (SAW) leads to deactivation of KBr whereas mechanical stress such as grinding leads to the formation of surface defects that become reaction centers. Desorption of SAW at T > 620 K induces high reactivity of the KBr sample at ambient temperature. A reaction mechanism encompassing all significant observations including unusual autocatalytic activity is given as there is no direct reaction of HOCl with solid KBr. It stresses the importance of adsorbed Br-containing species such as Br(2)(a) and HBr(a) that initiate the heterogeneous chemistry of HOCl on solid KBr in the presence of SAW. The role of surface acidity and SAW for the extent of reaction is emphasized.

  16. Effects of welding fumes on nuclear air cleaning system carbon adsorber banks

    SciTech Connect

    Roberson, P.W.

    1997-08-01

    Standard Technical Specifications for nuclear air cleaning systems include requirements for surveillance tests following fire, painting, or chemical release in areas communicating with the affected system. To conservatively implement this requirement, many plants categorize welding as a chemical release process, and institute controls to ensure that welding fumes do not interact with carbon adsorbers in a filter system. After reviewing research data that indicated welding had a minimal impact on adsorber iodine removal efficiency, further testing was performed with the goal of establishing a welding threshold. It was anticipated that some quantity of weld electrodes could be determined that had a corresponding detrimental impact on iodine removal efficiency for the exposed adsorber. This value could be used to determine a conservative sampling schedule that would allow the station to perform laboratory testing to ensure system degradation did not occur without a full battery of surveillance tests. A series of tests was designed to demonstrate carbon efficiency versus cumulative welding fume exposure. Three series of tests were performed, one for each of three different types of commonly used weld electrodes. Carbon sampling was performed at baseline conditions, and every five pounds of electrode thereafter. Two different laboratory tests were performed for each sample; one in accordance with ASTM 3803/1989 at 95% relative humidity and 30 degrees C, and another using the less rigorous conditions of 70% relative humidity and 80 degrees C. Review of the test data for all three types of electrodes failed to show a significant correlation between carbon efficiency degradation and welding fume exposure. Accordingly, welding is no longer categorized as a `chemical release process` at McGuire Nuclear Station, and limits on welding fume interaction with ventilation systems have been eliminated. 4 refs., 3 figs., 1 tab.

  17. Speciation of adsorbed yttrium and rare earth elements on oxide surfaces

    NASA Astrophysics Data System (ADS)

    Piasecki, Wojciech; Sverjensky, Dimitri A.

    2008-08-01

    The distribution of yttrium and the rare earth elements (YREE) between natural waters and oxide mineral surfaces depends on adsorption reactions, which in turn depend on the specific way in which YREE are coordinated to mineral surfaces. Recent X-ray studies have established that Y 3+ is adsorbed to the rutile (1 1 0) surface as a distinctive tetranuclear species. However, the hydrolysis state of the adsorbed cation is not known from experiment. Previous surface complexation models of YREE adsorption have suggested two to four cation hydrolysis states coexisting on oxide surfaces. In the present study, we investigate the applicability of the X-ray results to rare earth elements and to several oxides in addition to rutile using the extended triple-layer surface complexation model. The reaction producing a hydrolyzed tetranuclear surface species 4>SOH+M+2HO=(>SOH)2_M(OH)2++4H was found to account for a significant fraction of the adsorbed Y 3+, La 3+, Nd 3+, Gd 3+, and Yb 3+ on rutile, hematite, alumina and silica over wide ranges of pH and ionic strength. Where adsorption data were available as a function of surface coverage for hematite and silica, an additional reaction involving a mononuclear species could be used to account for the higher surface coverages. However, it is also possible that some of the higher surface coverage data refer to surface precipitation rather than adsorption. The results of the present study provide an internally consistent basis for describing YREE adsorption which could be used to investigate more complex systems in which YREE compete both in aqueous solution and on mineral surfaces with alkaline earths and ligands such as carbonate, sulfate, chloride and organic species, in order to build a predictive adsorption model applicable to natural waters.

  18. Electrochemical regeneration of a reduced graphene oxide/magnetite composite adsorbent loaded with methylene blue.

    PubMed

    Sharif, Farbod; Gagnon, Luke R; Mulmi, Suresh; Roberts, Edward P L

    2017-05-01

    In this work, two different reduced graphene oxide/iron oxide (rGO-IO) nanocomposites with different iron oxide loadings were fabricated using a one-step solvothermal method. The structure, properties and applications of the synthesized nanocomposites were evaluated with Raman spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, electron microscopy, and energy-dispersive X-ray spectroscopy. The iron oxide is in the form of magnetite (Fe3O4), so that the resultant adsorbent can readily be separated from the treated water using a magnetic field. The ability of the nanocomposites to remove methylene blue (MB) from water by adsorption was investigated. The highest adsorptive capacity observed was 39 mg g(-1), for the composite containing 60 wt% iron oxide. The adsorptive capacity of the rGO-IO decreased to 26 mg g(-1) when the mass fraction of iron oxide was increased to 75 wt%. Electrochemical regeneration of MB loaded rGO-IO was also investigated. The electrochemical regeneration was found to be rapid and with low electrical energy consumption relative to conventional adsorbents, due to the high electrical conductivity and nonporous surface of the rGO. A regeneration efficiency of 100% was obtained after 30 min of electrochemical treatment using a 2 mm thick bed of rGO-IO loaded with 39 mg g(-1) MB, using a current density of 10 mA cm(-2). Multiple adsorption-electrochemical regeneration cycles demonstrated that the surface of the rGO was modified leading to increase in the adsorptive capacity to around 80 mg g(-1) after the second regeneration cycle. The morphology of the rGO was observed to change significantly after electrochemical regeneration, suggesting that the rGO based adsorbent materials could only be used for a few cycles.

  19. Carbon coated magnetic nanoparticles as a novel magnetic solid phase extraction adsorbent for simultaneous extraction of methamphetamine and ephedrine from urine samples.

    PubMed

    Taghvimi, Arezou; Hamishehkar, Hamed

    2017-01-15

    This paper develops a highly selective, specific and efficient method for simultaneous determination of ephedrine and methamphetamine by a new carbon coated magnetic nanoparticles (C/MNPs) as a magnetic solid phase extraction (MSPE) adsorbent in biological urine medium. The characterization of synthesized magnetic nano adsorbent was completely carried out by various characterization techniques like Fourier transform infrared (FT-IR) spectroscopy, powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Nine important parameters influencing extraction efficiency including amount of adsorbent, amounts of sample volume, pH, type and amount of extraction organic solvent, time of extraction and desorption, agitation rate and ionic strength of extraction medium, were studied and optimized. Under optimized extraction conditions, a good linearity was observed in the concentration range of 100-2000ng/mL for ephedrine and 100-2500ng/mL for methamphetamine. Analysis of positive urine samples was carried out by proposed method with the recovery of 98.71 and 97.87% for ephedrine and methamphetamine, respectively. The results indicated that carbon coated magnetic nanoparticles could be applied in clinical and forensic laboratories for simultaneous determination of abused drugs in urine media.

  20. Adsorbent-adsorbate interactions in the adsorption of Cd(II) and Hg(II) on ozonized activated carbons.

    PubMed

    Sánchez-Polo, M; Rivera-Utrilla, J

    2002-09-01

    The present work investigated the effect of surface oxygenated groups on the adsorption of Cd(II) and Hg(II) by activated carbon. A study was undertaken to determine the adsorption isotherms and the influence of the pH on the adsorption of each metallic ion by a series of ozonized activated carbons. In the case of Cd(II), the adsorption capacity and the affinity of the adsorbent augmented with the increase in acid-oxygenated groups on the activated carbon surface. These results imply that electrostatic-type interactions predominate in this adsorption process. The adsorption observed at solution pH values below the pH(PZC) of the carbon indicates that other forces also participate in this process. Ionic exchange between -C pi-H3O+ interaction protons and Cd(II) ions would account for these findings. In the case of Hg(II), the adsorption diminished with an increase in the degree of oxidation of the activated carbon. The presence of electron-withdrawing groups on oxidized carbons decreases the electronic density of their surface, producing a reduction in the adsorbent-adsorbate dispersion interactions and in their reductive capacity, thus decreasing the adsorption of Hg(II) on the activated carbon. At pH values above 3, the pH had no influence on the adsorption of Hg(II) by the activated carbon, confirming that electrostatic interactions do not have a determinant influence on Hg(II) adsorption.

  1. Electric Field Cancellation on Quartz by Rb Adsorbate-Induced Negative Electron Affinity.

    PubMed

    Sedlacek, J A; Kim, E; Rittenhouse, S T; Weck, P F; Sadeghpour, H R; Shaffer, J P

    2016-04-01

    We investigate the (0001) surface of single crystal quartz with a submonolayer of Rb adsorbates. Using Rydberg atom electromagnetically induced transparency, we investigate the electric fields resulting from Rb adsorbed on the quartz surface, and measure the activation energy of the Rb adsorbates. We show that the adsorbed Rb induces negative electron affinity (NEA) on the quartz surface. The NEA surface allows low energy electrons to bind to the surface and cancel the electric field from the Rb adsorbates. Our results will be important for integrating Rydberg atoms into hybrid quantum systems, as fundamental probes of atom-surface interactions, and for studies of 2D electron gases bound to surfaces.

  2. Preparation, characterization, and phosphate removal and recovery of magnetic MnFe2O4 nano-particles as adsorbents.

    PubMed

    Xia, Shumei; Xu, Xiaoming; Xu, Changsong; Wang, Hongshuai; Zhang, Xiaowei; Liu, Guangmin

    2016-01-01

    Phosphate removal is an important method for controlling eutrophication in bodies of water. Adsorption is an effective phosphate removal approach. In this research, the adsorbent, namely, MnFe2O4, was prepared through the improved co-precipitation method and investigated in terms of phosphate removal. MnFe2O4 was characterized by scanning electron microscopy, vibrating sample magnetometry, X-ray diffraction, and Fourier transform infrared spectroscopy. Phosphate adsorption by MnFe2O4, desorption of adsorbed MnFe2O4 with the regeneration of desorbed MnFe2O4, and phosphate recovery were researched. Experimental results showed that adding the appropriate amount of polyethylene glycol to MnFe2O4 precursors during preparation inhibited the agglomeration of MnFe2O4 between particles because of the magnetic property of MnFe2O4 etc. High crystallinity and strong magnetism were achieved by MnFe2O4 at low temperatures. Average particle size was 5.1 nm. The hysteresis loops confirmed the ferrimagnetic behaviour of MnFe2O4 with a high saturation magnetization (i.e. 26.27 emu/g). The adsorption mechanism of phosphate was mainly physical. The prepared MnFe2O4 had a spinel structure. The proposed technique achieved a phosphate removal rate of 96.06%. A considerable amount of phosphate was desorbed from the adsorbed MnFe2O4 in 15 w/v% NaOH solution. The adsorption capacity of the desorbed MnFe2O4 could be restored to 96.73% in 10 w/v% NaNO3 solution through ion exchange. A sustainable phosphate source was recovered via hydroxyapatite crystallization in the desorption solution, which contained an abundant amount of phosphate as seed for suitable recovery condition. This finding suggested that MnFe2O4 could be a promising adsorbent for efficient phosphate removal.

  3. A molecular dynamics study on the transport of a charged biomolecule in a polymeric adsorbent medium and its adsorption onto a charged ligand

    NASA Astrophysics Data System (ADS)

    Riccardi, E.; Wang, J.-C.; Liapis, A. I.

    2010-08-01

    findings have significant practical implications to the design and construction of polymeric porous adsorbent media for effective bioseparations and to the synthesis and operation of processes employed in the separation of biomolecules. The modeling and analysis methods presented in this work could also be suitable for the study of biocatalysis where an enzyme is immobilized on the surface of the pores of a porous medium.

  4. A molecular dynamics study on the transport of a charged biomolecule in a polymeric adsorbent medium and its adsorption onto a charged ligand.

    PubMed

    Riccardi, E; Wang, J-C; Liapis, A I

    2010-08-28

    findings have significant practical implications to the design and construction of polymeric porous adsorbent media for effective bioseparations and to the synthesis and operation of processes employed in the separation of biomolecules. The modeling and analysis methods presented in this work could also be suitable for the study of biocatalysis where an enzyme is immobilized on the surface of the pores of a porous medium.

  5. The Effects of Organic Adsorbates on the Underpotential and Bulk Deposition of Silver on Polycrystalline Platinum Electrodes

    DTIC Science & Technology

    1994-03-14

    the Underpotential and Bulk Deposition of Silver on Polycrystalline Platinum Electrodes S.H. Harford, D.L. Taylor, and H.D. Abrufia Department of...Arlington, VA 22217 i1 iTITLE (Irlude Security Cla$slficatIon) The Effects of Organic Adsorbates on the Underpotential and Bulk Deposition of Silver on...through a nitrogen hetero-atom significantly hinder both the silver underpotential (UPD) and bulk deposition processes. The existence of a Pt/Ag

  6. The Dispersion Properties of Precipitated Calcium Carbonate Suspensions Adsorbed with Alkyl Polyglycoside in Aqueous Medium.

    PubMed

    Song, Myung-Geun; Kim, Jong-Yun; Kim, Jong-Duk

    2000-06-01

    The zeta potentials and dispersion properties of precipitated calcium carbonate suspensions adsorbed with alkyl polyglycosides in aqueous medium were investigated. Within the investigated pH ranges, the adsorption curves of alkyl polyglycosides on calcium carbonates show sigmoidal shapes, and the zeta potential decreases as the amount of adsorption increases. At positively charged surfaces of low pH, the adsorption amounts were greater than those at negatively charged surfaces, indicating that alkyl polyglycosides were negatively charged in aqueous solutions. At low concentrations of alkyl polyglycosides, the dispersion stabilities of suspensions were very poor and showed no linearity with zeta potentials over the entire range of pHs, which may be attributed to the onset of hydrophobic interaction between particles due to the adsorption of surfactant molecules. This destabilization continued until monolayer coverage by the surfactant layer was complete. Based on the classical DLVO theory, there may be a strong hydrophobic interaction between particles. Beyond monolayer adsorption, the dispersion stability increases, probably by the formation of hemimicelle or admicelle. Therefore, it is believed that ionization of alkyl polyglycosides and admicelles of surfactants on particle surface plays a key role in the stability of dispersions and the abrupt increase in adsorption. Copyright 2000 Academic Press.

  7. Polyacrylate adsorbents for the selective adsorption of cholesterol-rich lipoproteins from plasma or blood

    PubMed Central

    Heuck, Claus-Chr.

    2011-01-01

    Polyacrylate (PAA) adsorbents selectively bind low density lipoproteins (LDL) from human plasma and blood, whereas very low density lipoproteins (VLDL) are only minimally adsorbed. The adsorption of cholesterol-rich lipoproteins to PAA adsorbents is related to the molecular weight (mw) of the polyanion ligand. Ca++ and Mg++ inhibit the binding of LDL to PAA adsorbents. The chemical composition of the organic hardgels of the adsorbents does not have an influence on adsorption. The selective adsorption of LDL to PAA adsorbents can be explained to result from their low negative surface charge density and the specific colloid-chemical properties of the surface-bound PAA, which do not prevent LDL from binding to charge-like domains of the ligand. By contrast, VLDL and high density lipoproteins (HDL) are repelled from the adsorbents due to their higher negative surface charge density. PMID:21289994

  8. Polyacrylate adsorbents for the selective adsorption of cholesterol-rich lipoproteins from plasma or blood.

    PubMed

    Heuck, Claus-Chr

    2011-01-24

    Polyacrylate (PAA) adsorbents selectively bind low density lipoproteins (LDL) from human plasma and blood, whereas very low density lipoproteins (VLDL) are only minimally adsorbed. The adsorption of cholesterol-rich lipoproteins to PAA adsorbents is related to the molecular weight (mw) of the polyanion ligand. Ca(++) and Mg(++) inhibit the binding of LDL to PAA adsorbents. The chemical composition of the organic hardgels of the adsorbents does not have an influence on adsorption. The selective adsorption of LDL to PAA adsorbents can be explained to result from their low negative surface charge density and the specific colloid-chemical properties of the surface-bound PAA, which do not prevent LDL from binding to charge-like domains of the ligand. By contrast, VLDL and high density lipoproteins (HDL) are repelled from the adsorbents due to their higher negative surface charge density.

  9. Novel Anionic Clay Adsorbents for Boiler-Blow-Down Waters Reclaim and Reuse

    SciTech Connect

    Muhammad Sahimi; Theodore Tsotsis

    2010-01-08

    Arsenic (As) and Selenium (Se) are found in water in the form of oxyanions. Relatively high concentrations of As and Se have been reported both in power plant discharges, as well as, in fresh water supplies. The International Agency for Research on Cancer currently classifies As as a group 1 chemical, that is considered to be carcinogenic to humans. In Phase I of this project we studied the adsorption of As and Se by uncalcined and calcined layered double hydroxide (LDH). The focus of the present work is a systematic study of the adsorption of As and Se by conditioned LDH adsorbents. Conditioning the adsorbent significantly reduced the Mg and Al dissolution observed with uncalcined and calcined LDH. The adsorption rates and isotherms have been investigated in batch experiments using particles of four different particle size ranges. As(V) adsorption is shown to follow a Sips-type adsorption isotherm. The As(V) adsorption rate on conditioned LDH increases with decreasing adsorbent particle size; the adsorption capacity, on the other hand, is independent of the particle size. A homogeneous surface diffusion model (HSDM) and a bi-disperse pore model (BPM) - the latter viewing the LDH particles as assemblages of microparticles and taking into account bulk diffusion in the intraparticle pore space, and surface diffusion within the microparticles themselves - were used to fit the experimental kinetic data. The HSDM estimated diffusivity values dependent on the particle size, whereas the BPM predicted an intracrystalline diffusivity, which is fairly invariant with particle size. The removal of As(V) on conditioned LDH adsorbents was also investigated in flow columns, where the impact of important solution and operational parameters such as influent As concentration, pH, sorbent particle size and flow rate were studied. An early breakthrough and saturation was observed at higher flow rates and at higher influent concentrations, whereas a decrease in the sorbent particle

  10. The effect of gold nanoparticle structure on the conformation and function of adsorbed proteins

    NASA Astrophysics Data System (ADS)

    Gagner, Jennifer E.

    Many applications of nanobiomaterials rely on or are enhanced by specific, protein-mediated interactions with biological systems. These interactions can be engineered by chemically modifying the surface of the material to affect protein adsorption, or by altering the topography of the nanoscale surface. The attachment or adsorption of proteins onto materials can greatly affect the structure and subsequent function of those proteins, giving rise to unpredictable and potentially undesirable effects. Thus, it is essential to develop a detailed understanding of how nanostructured surface characteristics, such as atomic-scale topography, surface energy, and chemical structure may affect protein adsorption, structure, function, and stability. The presented work on gold nanoparticles (AuNP) in the forms of spheres (AuNS), rods (AuNR), cubes (AuNC) and octahedra (AuNO) will elucidate the effect of nanoparticle morphology on adsorbed model proteins lysozyme (Lyz) and α-chymotrypsin (ChT). It has been found that nanoparticle morphology does affect the structure of adsorbed proteins as well as the extent of the surface coverage; however, the final form of the nano-bio conjugate is protein specific. Lyz conjugates underwent loss of structure and rapid aggregation regardless of AuNP morphology; however, ChT conjugates exhibited no structure loss when immobilized on AuNS, and a significant, loading specific structure loss when adsorbed on AuNR. Further work will be presented on efforts to determine the role of crystal structure, surface energy, and ligand chemistry on adsorbed proteins. Wet chemical methods are used to synthesize AuNC with f100g facets and AuNO with f111g facets. Nanoparticles are characterized through electron microscopy, X-ray and electron diffraction, X-ray photoelectron spectroscopy and inductively coupled plasma mass spectroscopy. Protein conjugation and changes in protein structure are monitored through a variety of physical and spectroscopic techniques

  11. STM observation of the chemical reaction of atomic hydrogen on the N-adsorbed Cu(001) surface

    NASA Astrophysics Data System (ADS)

    Hattori, Takuma; Yamada, Masamichi; Komori, Fumio

    2017-01-01

    Chemical reaction of atomic hydrogen with the N-adsorbed Cu(001) surfaces was investigated at room temperature by scanning tunnel microscopy. At the low exposure of atomic hydrogen, it reacted with the N atoms and turned to be the NH species on the surface. The reaction rate is proportional to the amount of the unreacted N atoms. By increasing the exposure of atomic hydrogen from this condition, the amount of nitrogen species on the surface decreased. This is attributed to the formation of ammonia and its desorption from the surface. The NH species on the surface turn to NH3 through the surface NH2 species by atomic hydrogen. Coexistence of the clean Cu surface enhances the rate of ammonia formation owing to atomic hydrogen migrating on the clean surface.

  12. Efficiency of basalt zeolite and Cuban zeolite to adsorb ammonia released from poultry litter.

    PubMed

    Nuernberg, Giselle B; Moreira, Marcelo A; Ernani, Paulo R; Almeida, Jaime A; Maciel, Tais M

    2016-12-01

    Confined poultry production is an important livestock activity, which generates large amounts of waste associated with the potential for environmental pollution and ammonia (NH3) emissions. The release of ammonia negatively affects poultry production and decreases the N content of wastes that could be used as soil fertilizers. The objective of this study was to evaluate a low-cost, simple and rapid method to simulate ammonia emissions from poultry litter as well as to quantify the reduction in the ammonia emissions to the environment employing two adsorbent zeolites, a commercial Cuban zeolite (CZ) and a ground basalt Brazilian rock containing zeolite (BZ). The experiments were conducted in a laboratory, in 2012-2013. The zeolites were characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), physical adsorption of N2 (BET) and scanning electron microscopy (SEM). Ammonia released from poultry litter and its simulation from NH4OH solution presented similar capture rates of 7.99 × 10(-5) and 7.35 × 10(-5) mg/h, respectively. Both zeolites contain SiO2 and Al2O3 as major constituents, with contents of 84% and 12% in the CZ, and 51% and 12% in the BZ, respectively, besides heulandite groups. Their BET surface areas were 89.4 and 11.3 m(2) g(-1), respectively, and the two zeolites had similar surface morphologies. The zeolites successfully adsorbed the ammonia released, but CZ was more efficient than BZ, since to capture all of the ammonia 5 g of CZ and 20 g of BZ were required. This difference is due to higher values for the superficial area, porosity, CEC and acid site strength of CZ relatively to BZ. The proposed methodology was shown to be an efficient method to simulate and quantify the ammonia released from poultry litter.

  13. Preparation of activated carbon from waste plastics polyethylene terephthalate as adsorbent in natural gas storage

    NASA Astrophysics Data System (ADS)

    Yuliusman; Nasruddin; Sanal, A.; Bernama, A.; Haris, F.; Ramadhan, I. T.

    2017-02-01

    The main problem is the process of natural gas storage and distribution, because in normal conditions of natural gas in the gas phase causes the storage capacity be small and efficient to use. The technology is commonly used Compressed Natural Gas (CNG) and Liquefied Natural Gas (LNG). The weakness of this technology safety level is low because the requirement for high-pressure CNG (250 bar) and LNG requires a low temperature (-161°C). It takes innovation in the storage of natural gas using the technology ANG (Adsorbed Natural Gas) with activated carbon as an adsorbent, causing natural gas can be stored in a low pressure of about 34.5. In this research, preparation of activated carbon using waste plastic polyethylene terephthalate (PET). PET plastic waste is a good raw material for making activated carbon because of its availability and the price is a lot cheaper. Besides plastic PET has the appropriate characteristics as activated carbon raw material required for the storage of natural gas because the material is hard and has a high carbon content of about 62.5% wt. The process of making activated carbon done is carbonized at a temperature of 400 ° C and physical activation using CO2 gas at a temperature of 975 ° C. The parameters varied in the activation process is the flow rate of carbon dioxide and activation time. The results obtained in the carbonization process yield of 21.47%, while the yield on the activation process by 62%. At the optimum process conditions, the CO2 flow rate of 200 ml/min and the activation time of 240 minutes, the value % burn off amounted to 86.69% and a surface area of 1591.72 m2/g.

  14. Carbon fibers: Thermochemical recovery from advanced composite materials and activation to an adsorbent

    NASA Astrophysics Data System (ADS)

    Staley, Todd Andrew

    This research addresses an expanding waste disposal problem brought about by the increasing use of advanced composite materials, and the lack of technically and environmentally viable recycling methods for these materials. A thermochemical treatment process was developed and optimized for the recycling of advanced composite materials. Counter-current gasification was employed for the treatment of carbon fiber reinforced-epoxy resin composite wastes. These materials were treated, allowing the reclamation of the material's valuable components. As expected in gasification, the organic portion of the waste was thermochemically converted to a combustible gas with small amounts of organic compounds that were identified by GC/MS. These compounds were expected based on data in the literature. The composites contain 70% fiber reinforcement, and gasification yielded approximately 70% recovered fibers, representing nearly complete recovery of fibers from the waste. Through SEM and mechanical testing, the recovered carbon fibers were found to be structurally and mechanically intact, and amenable to re-use in a variety of applications, some of which were identified and tested. In addition, an application was developed for the carbon fiber component of the waste, as an activated carbon fiber adsorbent for the treatment of wastewaters. This novel class of adsorbent was found to have adsorption rates, for various organic molecules, up to a factor of ten times those of commercial granular activated carbon, and adsorption capacities similar to conventional activated carbons. Overall, the research addresses an existing environmental waste problem, employing a thermochemical technique to recycle and reclaim the waste. Components of the reclaimed waste material are then employed, after further modification, to address other existing and potential environmental waste problems.

  15. Water and ion transport in ultra-adsorbing porous magnesium carbonate studied by dielectric spectroscopy

    NASA Astrophysics Data System (ADS)

    Pochard, Isabelle; Frykstrand, Sara; Ahlström, Olle; Forsgren, Johan; Strømme, Maria

    2014-01-01

    Porous materials are used in application areas ranging from drug and vaccine delivery, medical implants, molecular sieves and cosmetics to catalysis and humidity control. In the present work, we employed an alternative approach to gain in-depth understanding about water interaction properties in such materials by the use of dielectric spectroscopy and thereby show that it is possible to obtain information that is not accessible from the more commonly employed water interaction analysis techniques. Specifically, the complex dielectric response of Upsalite, a novel, super-hydroscopic, high-surface area, porous magnesium carbonate material was measured in isothermal frequency scans between 10-3 and 106 Hz at controlled relative humidity (RH). We found the dielectric constant of the dry material to be 1.82. The ratio of bound to free water present in Upsalite after adsorption at room temperature was found to be high irrespective of the surrounding humidity with values ranging from ˜67% to ˜90%. We further found that OH- ions are the charge carriers responsible for the electrode polarization observed in the dielectric response and that the amount of these ions that are free to move in the material corresponds to a concentration of the order of 1-10 μmol l-1 independent of RH. Finally, the OH- diffusion coefficient displayed a drastic decrease with decreasing RH, typical of transport in unsaturated conditions. The presented results provide detailed insight about water interactions in the novel water adsorbing material under study and it is foreseen that the employed analysis methods can be used to evaluate other types of moisture adsorbing materials as well as the movement of functional species in the pores of inorganic drug delivery materials and materials tailored for adsorption of harmful charged species.

  16. Étude des chimisorptions de H2 et de CO sur un catalyseur Ru/Al2O3 en relation avec l'hydrogénation isotherme d'espèces carbonées adsorbées

    NASA Astrophysics Data System (ADS)

    Nawdali, M.; Ahlafi, H.; Bianchi, D.

    1999-04-01

    H2 and CO chemisorptions, on a reduced 3.5% Ru/Al2O3 catalyst, are studied by Temperature Programmed Desorption (TPD) and FTIR spectroscopy. The H2 chemisorption is an activated process. The amount of the irreversibly adsorbed species at saturation of the surface is 76μmolH2/g.cat. attributed to two adsorbed species. The adsorption of CO is not activated. The FTIR spectra show that various adsorbed species are formed. The main species is the linear CO species. The CO adsorption after an initial hydrogen chemisorption leads to the desorption of 52% of the amount of adsorbed hydrogen. At the opposite, CO is not desorbed if the adsorption of hydrogen is performed on a surface which is initially saturated with CO. In this case, the H2 chemisorption involves other sites than the ones of the reduced surface. Les chimisorptions de H2 et de CO, individuelles et séquentielles (adsorption de H2 puis de CO et adsorption de CO puis de H2), sur un catalyseur Ru/Al2O3 réduit sont étudiées par Désorption à Température Programmée et par spectroscopie IRTF. Il est montré que le CO déplace une fraction importante de l'hydrogène préadsorbé mais que l'hydrogène peut être adsorbé sur une surface ayant adsorbé du CO sans déplacement des différentes formes adsorbées de CO. Les résultats sont interprétés en considérant que les sites adsorbant l'hydrogène sur une surface libre sont différents de ceux mis en jeu sur une surface ayant adsorbé le CO.

  17. 2D DIGE saturation labeling for minute sample amounts.

    PubMed

    Arnold, Georg J; Fröhlich, Thomas

    2012-01-01

    The 2D DIGE technique, based on fluorophores covalently linked to amino acid side chain residues and the concept of an internal standard, has significantly improved reproducibility, sensitivity, and the dynamic range of protein quantification. In saturation DIGE, sulfhydryl groups of cysteines are labeled with cyanine dyes to completion, providing a so far unraveled sensitivity for protein detection and quantification in 2D gel-based proteomic experiments. Only a few micrograms of protein per 2D gel facilitate the analysis of about 2,000 analytes from complex mammalian cell or tissue samples. As a consequence, 2D saturation DIGE is the method of choice when only minute sample amounts are available for quantitative proteome analysis at the level of proteins rather than peptides. Since very low amounts of samples have to be handled in a reproducible manner, saturation DIGE-based proteomic experiments are technically demanding. Moreover, successful saturation DIGE approaches require a strict adherence to adequate reaction conditions at each step. This chapter is dedicated to colleagues already experienced in 2D PAGE protein separation and intends to support the establishment of this ultrasensitive technique in proteomic workgroups. We provide basic guidelines for the experimental design and discuss crucial aspects concerning labeling chemistry, sample preparation, and pitfalls caused by labeling artifacts. A detailed step-by-step protocol comprises all aspects from initial sample preparation to image analysis and statistical evaluation. Furthermore, we describe the generation of preparative saturation DIGE gels necessary for mass spectrometry-based spot identification.

  18. Controlling the magnetism of adsorbed metal-organic molecules

    NASA Astrophysics Data System (ADS)

    Kuch, Wolfgang; Bernien, Matthias

    2017-01-01

    Gaining control on the size or the direction of the magnetic moment of adsorbed metal-organic molecules constitutes an important step towards the realization of a surface-mounted molecular spin electronics. Such control can be gained by taking advantage of interactions of the molecule’s magnetic moment with the environment. The paramagnetic moments of adsorbed metal-organic molecules, for example, can be controlled by the interaction with magnetically ordered substrates. Metalloporphyrins and -phthalocyanines display a quasi-planar geometry, allowing the central metal ion to interact with substrate electronic states. This can lead to magnetic coupling with a ferromagnetic or even antiferromagnetic substrate. The molecule-substrate coupling can be mediated and controlled by insertion layers such as oxygen atoms, graphene, or nonmagnetic metal layers. Control on the magnetic properties of adsorbed metalloporphyrins or -phthalocyanines can also be gained by on-surface chemical modification of the molecules. The magnetic moment or the magnetic coupling to ferromagnetic substrates can be changed by adsorption and thermal desorption of small molecules that interact with the fourfold-coordinated metal center via the remaining axial coordination site. Spin-crossover molecules, which possess a metastable spin state that can be switched by external stimuli such as temperature or light, are another promising class of candidates for control of magnetic properties. However, the immobilization of such molecules on a solid surface often results in a quench of the spin transition due to the interaction with the substrate. We present examples of Fe(II) spin-crossover complexes in direct contact with a solid surface that undergo a reversible spin-crossover transition as a function of temperature, by illumination with visible light, or can be switched by the tip of a scanning tunneling microscope.

  19. Controlling the magnetism of adsorbed metal-organic molecules.

    PubMed

    Kuch, Wolfgang; Bernien, Matthias

    2017-01-18

    Gaining control on the size or the direction of the magnetic moment of adsorbed metal-organic molecules constitutes an important step towards the realization of a surface-mounted molecular spin electronics. Such control can be gained by taking advantage of interactions of the molecule's magnetic moment with the environment. The paramagnetic moments of adsorbed metal-organic molecules, for example, can be controlled by the interaction with magnetically ordered substrates. Metalloporphyrins and -phthalocyanines display a quasi-planar geometry, allowing the central metal ion to interact with substrate electronic states. This can lead to magnetic coupling with a ferromagnetic or even antiferromagnetic substrate. The molecule-substrate coupling can be mediated and controlled by insertion layers such as oxygen atoms, graphene, or nonmagnetic metal layers. Control on the magnetic properties of adsorbed metalloporphyrins or -phthalocyanines can also be gained by on-surface chemical modification of the molecules. The magnetic moment or the magnetic coupling to ferromagnetic substrates can be changed by adsorption and thermal desorption of small molecules that interact with the fourfold-coordinated metal center via the remaining axial coordination site. Spin-crossover molecules, which possess a metastable spin state that can be switched by external stimuli such as temperature or light, are another promising class of candidates for control of magnetic properties. However, the immobilization of such molecules on a solid surface often results in a quench of the spin transition due to the interaction with the substrate. We present examples of Fe(II) spin-crossover complexes in direct contact with a solid surface that undergo a reversible spin-crossover transition as a function of temperature, by illumination with visible light, or can be switched by the tip of a scanning tunneling microscope.

  20. Highly effective removal of mercury and lead ions from wastewater by mercaptoamine-functionalised silica-coated magnetic nano-adsorbents: Behaviours and mechanisms

    NASA Astrophysics Data System (ADS)

    Bao, Shuangyou; Li, Kai; Ning, Ping; Peng, Jinhui; Jin, Xu; Tang, Lihong

    2017-01-01

    A novel hybrid material was fabricated using mercaptoamine-functionalised silica-coated magnetic nanoparticles (MAF-SCMNPs) and was effective in the extraction and recovery of mercury and lead ions from wastewater. The properties of this new magnetic material were explored using various characterisation and analysis methods. Adsorbent amounts, pH levels and initial concentrations were optimised to improve removal efficiency. Additionally, kinetics, thermodynamics and adsorption isotherms were investigated to determine the mechanism by which the fabricated MAF-SCMNPs adsorb heavy metal ions. The results revealed that MAF-SCMNPs were acid-resistant. Sorption likely occurred by chelation through the amine group and ion exchange between heavy metal ions and thiol functional groups on the nanoadsorbent surface. The equilibrium was attained within 120 min, and the adsorption kinetics showed pseudo-second-order (R2 > 0.99). The mercury and lead adsorption isotherms were in agreement with the Freundlich model, displaying maximum adsorption capacities of 355 and 292 mg/g, respectively. The maximum adsorptions took place at pH 5-6 and 6-7 for Hg(II) and Pb(II), respectively. The maximum adsorptions were observed at 10 mg and 12 mg adsorbent quantities for Hg(II) and Pb(II), respectively. The adsorption process was endothermic and spontaneous within the temperature range of 298-318 K. This work demonstrates a unique magnetic nano-adsorbent for the removal of Hg(II) and Pb(II) from wastewater.