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Sample records for ion exchange kinetics

  1. Cesium Ion Exchange Loading Kinetics Testing with SRF Resin

    SciTech Connect

    Russell, Renee L.; Rinehart, Donald E.; Brown, Garrett N.; Peterson, Reid A.

    2012-11-02

    Ion exchange using the Spherical Resorcinol-Formaldehyde (SRF) resin has been selected by the U.S. Department of Energy’s Office of River Protection for use in the Pretreatment Facility of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) and for potential application in an at-tank deployment for removing 137Cs. Recent proposed changes to the WTP ion exchange process baseline indicate that loading may include a broader range of sodium molarities (2 to 8 M) due to caustic leaching and higher temperatures (50°C) to alleviate post-filtration precipitation issues prior to reaching the ion exchange columns. Therefore, it is important to understand the behavior of SRF resin performance under the conditions expected with the new equipment and process changes. This research examined the impact of linear load velocity (4, 6, 8 cm/min), initial sodium concentration (2, 5, 8 M), initial sodium-to-cesium ratio (1.4E+05, 2.1E+05, 2.8E+05 mol/mol), initial sodium-to-hydroxide ratio (2.0, 3.0, 4.0 mol/mol), and resin degradation during extended solution flow using elevated temperature (45°, 50°, 55°, 60°, 65°, 75°C). Testing was performed using a~2mL column packed with SRF resin with feed flowing through it in an up-flow pattern. Samples were taken at set intervals and the data analyzed to help understand the impact of these conditions on the SRF resin performance. It was found that the loading kinetics were not significantly impacted by the sodium concentration over the range tested. However, the loading kinetics were impacted by the linear load velocity. These results indicated that at the test temperature, the adsorption of cesium is strongly dependent on mass transfer through the film and not significantly impacted by interparticle diffusion. Testing for extended times at elevated temperatures showed that the resin does degrade and loading capacity is reduced at and above 45°C. Above 60°C the resin appears to not load at all.

  2. A comparative study of ion exchange kinetics in zinc/lead-modified zeolite-clinoptilolite systems.

    PubMed

    Trgo, M; Perić, J; Medvidović, N Vukojević

    2006-08-25

    The kinetics of zinc and lead ions removal by modified zeolite-clinoptilolite has been investigated. The rate of the ion exchange process for lead ions is faster than for zinc ions, as well as the time needed to reach the equilibrium. The ion exchange capacity of zeolite of lead ions is doubly higher than that of zinc ions. Diffusion models according to the Vermeulen's approximation, the parabolic diffusion model and the homogeneous diffusion model have been tested with the experimental data of ion exchange for zinc and lead. For both systems examined, the best fit of the models proposed with the experimental data was shown by the Vermeulen's approximation and the homogeneous diffusion model with t-->t(infinity). The diffusion coefficients are calculated from kinetic models of lead ions they are of the order of 10(-6)cm(2)/min, constant for all examined initial concentrations and not dependent on time. The diffusion coefficients in the system of zinc ions is of the order of 10(-8)cm(2)/min, also independent of initial concentrations, but decreasing with time from the beginning of ion exchange to the equilibrium.

  3. Semi-aerobic stabilized landfill leachate treatment by ion exchange resin: isotherm and kinetic study

    NASA Astrophysics Data System (ADS)

    Zamri, Mohd Faiz Muaz Ahmad; Kamaruddin, Mohamad Anuar; Yusoff, Mohd Suffian; Aziz, Hamidi Abdul; Foo, Keng Yuen

    2015-03-01

    This study was carried out to investigate the treatability of ion exchange resin (Indion MB 6 SR) for the removal of chromium (VI), aluminium (III), zinc (II), copper (II), iron (II), and phosphate (PO4)3-, chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and colour from semi-aerobic stabilized leachate by batch test. A range of ion exchange resin dosage was tested towards the removal efficiency of leachate parameters. It was observed that equilibrium data were best represented by the Langmuir model for metal ions and Freundlich was ideally fit for COD, NH3-N and colour. Intra particle diffusion model, pseudo first-order and pseudo second-order isotherm models were found ideally fit with correlation of the experimental data. The findings revealed that the models could describe the ion exchange kinetic behaviour efficiently, which further suggests comprehensive outlook for the future research in this field.

  4. Semi-aerobic stabilized landfill leachate treatment by ion exchange resin: isotherm and kinetic study

    NASA Astrophysics Data System (ADS)

    Zamri, Mohd Faiz Muaz Ahmad; Kamaruddin, Mohamad Anuar; Yusoff, Mohd Suffian; Aziz, Hamidi Abdul; Foo, Keng Yuen

    2017-05-01

    This study was carried out to investigate the treatability of ion exchange resin (Indion MB 6 SR) for the removal of chromium (VI), aluminium (III), zinc (II), copper (II), iron (II), and phosphate (PO4)3-, chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and colour from semi-aerobic stabilized leachate by batch test. A range of ion exchange resin dosage was tested towards the removal efficiency of leachate parameters. It was observed that equilibrium data were best represented by the Langmuir model for metal ions and Freundlich was ideally fit for COD, NH3-N and colour. Intra particle diffusion model, pseudo first-order and pseudo second-order isotherm models were found ideally fit with correlation of the experimental data. The findings revealed that the models could describe the ion exchange kinetic behaviour efficiently, which further suggests comprehensive outlook for the future research in this field.

  5. Impact of natural organic matter properties on the kinetics of suspended ion exchange process.

    PubMed

    Bazri, Mohammad Mahdi; Mohseni, Madjid

    2016-03-15

    Removal kinetics of four standard organic matter isolates under the application of strongly basic ion exchange resins (IEX) in suspended mode was studied under commercial application conditions. Suwannee River natural organic matter (SRNOM), SR fulvic acid (SRFA), and Pony Lake fulvic acid (PLFA) were greatly removed (>90%) and highly preferred by IEX resins (α > 5, over Cl(-), and HCO3(-)) while SR humic acid (SRHA) was the least preferred organic structure among the four isolates studied (α ≈ 1). Moreover, the efficacy of removal for fulvic acids (i.e., SRFA, PLFA) was consistent over consecutive reuse of IEX resins (i.e., loading cycles) whereas it decreased for SRNOM and SRHA over the course of operation. The stoichiometric correlation between the chloride released from the resins as a result of organic molecules uptake indicated that ion exchange was the dominant mechanism. Results obtained indicated that molecular weight and charge density of isolates played a major role in the performance of ion exchange process for organic matter removal. Furthermore, various empirical and physical models were evaluated using the experimental data and pore diffusion was found to be the rate-liming step during the uptake of organic matters; hence, it was used as the appropriate model to predict the kinetics of removal. Consequently, free liquid diffusivities and effective pore diffusion coefficients of organic molecules were estimated and findings were in agreement with the literature data that were obtained from spectrophotometric methods.

  6. Ion Exchange Equilibrium and Kinetic Properties of Polyacrylate Films and Applications to Chemical Analysis and Environmental Decontamination

    NASA Technical Reports Server (NTRS)

    Tanner, Stephen P.

    1997-01-01

    One of the goals of the original proposal was to study how cross-linking affects the properties of an ion exchange material(IEM) developed at Lewis Research Center. However, prior to the start of this work, other workers at LERC investigated the effect of cross-linking on the properties of this material. Other than variation in the ion exchange capacity, the chemical characteristics were shown to be independent of the cross-linking agent, and the degree of cross-linking. New physical forms of the film were developed (film, supported film, various sizes of beads, and powder). All showed similar properties with respect to ion exchange equilibria but the kinetics of ion exchange depended on the surface area per unit mass; the powder form of the IEM exchanging much more rapidly than the other forms. The research performed under this grant was directed towards the application of the IEM to the analysis of metal ions at environmental concentrations.

  7. Rate theory of solvent exchange and kinetics of Li(+) - BF4 (-)/PF6 (-) ion pairs in acetonitrile.

    PubMed

    Dang, Liem X; Chang, Tsun-Mei

    2016-09-07

    In this paper, we describe our efforts to apply rate theories in studies of solvent exchange around Li(+) and the kinetics of ion pairings in lithium-ion batteries (LIBs). We report one of the first computer simulations of the exchange dynamics around solvated Li(+) in acetonitrile (ACN), which is a common solvent used in LIBs. We also provide details of the ion-pairing kinetics of Li(+)-[BF4] and Li(+)-[PF6] in ACN. Using our polarizable force-field models and employing classical rate theories of chemical reactions, we examine the ACN exchange process between the first and second solvation shells around Li(+). We calculate exchange rates using transition state theory and weighted them with the transmission coefficients determined by the reactive flux, Impey, Madden, and McDonald approaches, and Grote-Hynes theory. We found the relaxation times changed from 180 ps to 4600 ps and from 30 ps to 280 ps for Li(+)-[BF4] and Li(+)-[PF6] ion pairs, respectively. These results confirm that the solvent response to the kinetics of ion pairing is significant. Our results also show that, in addition to affecting the free energy of solvation into ACN, the anion type also should significantly influence the kinetics of ion pairing. These results will increase our understanding of the thermodynamic and kinetic properties of LIB systems.

  8. Rate theory of solvent exchange and kinetics of Li+ - BF4-/PF6- ion pairs in acetonitrile

    NASA Astrophysics Data System (ADS)

    Dang, Liem X.; Chang, Tsun-Mei

    2016-09-01

    In this paper, we describe our efforts to apply rate theories in studies of solvent exchange around Li+ and the kinetics of ion pairings in lithium-ion batteries (LIBs). We report one of the first computer simulations of the exchange dynamics around solvated Li+ in acetonitrile (ACN), which is a common solvent used in LIBs. We also provide details of the ion-pairing kinetics of Li+-[BF4] and Li+-[PF6] in ACN. Using our polarizable force-field models and employing classical rate theories of chemical reactions, we examine the ACN exchange process between the first and second solvation shells around Li+. We calculate exchange rates using transition state theory and weighted them with the transmission coefficients determined by the reactive flux, Impey, Madden, and McDonald approaches, and Grote-Hynes theory. We found the relaxation times changed from 180 ps to 4600 ps and from 30 ps to 280 ps for Li+-[BF4] and Li+-[PF6] ion pairs, respectively. These results confirm that the solvent response to the kinetics of ion pairing is significant. Our results also show that, in addition to affecting the free energy of solvation into ACN, the anion type also should significantly influence the kinetics of ion pairing. These results will increase our understanding of the thermodynamic and kinetic properties of LIB systems.

  9. Cs{sup +} ion exchange kinetics in complex electrolyte solutions using hydrous crystalline silicotitanates

    SciTech Connect

    Gu, D.; Nguyen, L.; Philip, C.V.; Huckman, M.E.; Anthony, R.G.; Miller, J.E.; Trudell, D.E.

    1997-12-01

    TAM-5 is a hydrous crystalline sodium silicotitanate inorganic ion exchanger with a high selectivity for Cs{sup +}. The kinetics of Cs{sup +}-Na{sup +} ion exchange using TAM-5 in multicomponent electrolyte solutions were determined using batch experiments. For the powder, which is composed of crystals, a single-phase, homogeneous model fit the data best. For the granules, which were prepared from the powder, a two-phase, heterogeneous model resulted in an excellent fit of the data. Macropore and crystal diffusivities were determined by fitting the model to experimental data collected on the powder and the granules. Intracrystalline diffusivities were concentration dependent and were on the order of 10{sup {minus}19} m{sup 2}/s. Macropore diffusivities were on the order of 10{sup {minus}10} m{sup 2}/s. Resistance to diffusion in the macropores was not significant for granules with diameters less than 15 {micro}m. A two-phase, homogeneous model, where liquid within the pores is in equilibrium with the solid, was also evaluated for the granules. Surprisingly, for the granules, an excellent fit of the data was obtained; however, the effective macropore diffusivity was 1.1 {times} 10{sup {minus}11} m{sup 2}/s, an order of magnitude smaller than the macropore diffusivity found using the two-phase, heterogeneous model.

  10. Kinetics of nitrate and perchlorate removal and biofilm stratification in an ion exchange membrane bioreactor.

    PubMed

    Ricardo, Ana R; Carvalho, Gilda; Velizarov, Svetlozar; Crespo, João G; Reis, Maria A M

    2012-09-15

    The biological degradation of nitrate and perchlorate was investigated in an ion exchange membrane bioreactor (IEMB) using a mixed anoxic microbial culture and ethanol as the carbon source. In this process, a membrane-supported biofilm reduces nitrate and perchlorate delivered through an anion exchange membrane from a polluted water stream, containing 60 mg/L of NO₃⁻ and 100 μg/L of ClO₄⁻. Under ammonia limiting conditions, the perchlorate reduction rate decreased by 10%, whereas the nitrate reduction rate was unaffected. Though nitrate and perchlorate accumulated in the bioreactor, their concentrations in the treated water (2.8 ± 0.5 mg/L of NO₃⁻ and 7.0 ± 0.8 μg/L of ClO₄⁻, respectively) were always below the drinking water regulatory levels, due to Donnan dialysis control of the ionic transport in the system. Kinetic parameters determined for the mixed microbial culture in suspension showed that the nitrate reduction rate was 35 times higher than the maximum perchlorate reduction rate. It was found that perchlorate reduction was inhibited by nitrate, since after nitrate depletion perchlorate reduction rate increased by 77%. The biofilm developed in the IEMB was cryosectioned and the microbial population was analyzed by fluorescence in situ hybridization (FISH). The results obtained seem to indicate that the kinetic advantage of nitrate reduction favored accumulation of denitrifiers near the membrane, whereas per(chlorate) reducing bacteria were mainly positioned at the biofilm outer surface, contacting the biomedium. As a consequence of the biofilm stratification, the reduction of perchlorate and nitrate occur sequentially in space allowing for the removal of both ions in the IEMB. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences.

    PubMed

    Yuan, Jing; Gao, Yanan; Wang, Xinyu; Liu, Hongzhuo; Che, Xin; Xu, Lu; Yang, Yang; Wang, Qifang; Wang, Yan; Li, Sanming

    2014-01-01

    Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug-fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug-fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid.

  12. Ion exchange kinetics of magnetic alginate ferrogel beads produced by external gelation.

    PubMed

    Teixeira, Vânea Ferreira Torres; Pereira, Nádia Rosa; Waldman, Walter Ruggeri; Ávila, Ana Luiza Cassiano Dias; Pérez, Victor Haber; Rodríguez, Rubén Jesus Sánchez

    2014-10-13

    This paper reports on a study of the influence of sodium alginate concentration and iron addition on the ion exchange kinetics of calcium alginate ferrogel beads produced by external gelation. The calcium absorption and sodium release of the beads were fitted to Fick's second law for unsteady state diffusion in order to obtain the effective diffusion coefficients of Na(+) and Ca(2+). The dried beads were characterized concerning their thermal stability, particle size distribution and morphology. The gelation kinetics showed that an increase in alginate concentration from 1% to 2% increased the Ca(2+) equilibrium concentration, but presented no effect on Ca(2+) effective diffusion coefficient. Alginate concentration higher than 2% promoted saturation of binding sites at the bead surfaces. The addition of iron promoted faster diffusion of Ca(2+) inside the gel beads and reduced the Ca(2+) equilibrium concentration. Also, iron particles entrapped in the alginate gel beads promoted greater absorption of water compared to pure alginate gel and lower thermal stability of the beads. The main diffusion of Ca(2+) into and Na(+) out from the bead took place during the first 60 min, during which almost 85-90% of the Ca(2+) equilibrium concentration is achieved, indicating that this period is sufficient to produce a Ca-alginate bead with high crosslinking of the polymer network. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Gas-Phase Hydrogen-Deuterium Exchange Labeling of Select Peptide Ion Conformer Types: a Per-Residue Kinetics Analysis.

    PubMed

    Khakinejad, Mahdiar; Kondalaji, Samaneh Ghassabi; Tafreshian, Amirmahdi; Valentine, Stephen J

    2015-07-01

    The per-residue, gas-phase hydrogen deuterium exchange (HDX) kinetics for individual amino acid residues on selected ion conformer types of the model peptide KKDDDDDIIKIIK have been examined using ion mobility spectrometry (IMS) and HDX-tandem mass spectrometry (MS/MS) techniques. The [M + 4H](4+) ions exhibit two major conformer types with collision cross sections of 418 Å(2) and 446 Å(2); the [M + 3H](3+) ions also yield two different conformer types having collision cross sections of 340 Å(2) and 367 Å(2). Kinetics plots of HDX for individual amino acid residues reveal fast- and slow-exchanging hydrogens. The contributions of each amino acid residue to the overall conformer type rate constant have been estimated. For this peptide, N- and C-terminal K residues exhibit the greatest contributions for all ion conformer types. Interior D and I residues show decreased contributions. Several charge state trends are observed. On average, the D residues of the [M + 3H](3+) ions show faster HDX rate contributions compared with [M + 4H](4+) ions. In contrast the interior I8 and I9 residues show increased accessibility to exchange for the more elongated [M + 4H](4+) ion conformer type. The contribution of each residue to the overall uptake rate showed a good correlation with a residue hydrogen accessibility score model calculated using a distance from charge site and initial incorporation site for nominal structures obtained from molecular dynamic simulations (MDS).

  14. Gas-Phase Hydrogen-Deuterium Exchange Labeling of Select Peptide Ion Conformer Types: a Per-Residue Kinetics Analysis

    NASA Astrophysics Data System (ADS)

    Khakinejad, Mahdiar; Kondalaji, Samaneh Ghassabi; Tafreshian, Amirmahdi; Valentine, Stephen J.

    2015-07-01

    The per-residue, gas-phase hydrogen deuterium exchange (HDX) kinetics for individual amino acid residues on selected ion conformer types of the model peptide KKDDDDDIIKIIK have been examined using ion mobility spectrometry (IMS) and HDX-tandem mass spectrometry (MS/MS) techniques. The [M + 4H]4+ ions exhibit two major conformer types with collision cross sections of 418 Å2 and 446 Å2; the [M + 3H]3+ ions also yield two different conformer types having collision cross sections of 340 Å2 and 367 Å2. Kinetics plots of HDX for individual amino acid residues reveal fast- and slow-exchanging hydrogens. The contributions of each amino acid residue to the overall conformer type rate constant have been estimated. For this peptide, N- and C-terminal K residues exhibit the greatest contributions for all ion conformer types. Interior D and I residues show decreased contributions. Several charge state trends are observed. On average, the D residues of the [M + 3H]3+ ions show faster HDX rate contributions compared with [M + 4H]4+ ions. In contrast the interior I8 and I9 residues show increased accessibility to exchange for the more elongated [M + 4H]4+ ion conformer type. The contribution of each residue to the overall uptake rate showed a good correlation with a residue hydrogen accessibility score model calculated using a distance from charge site and initial incorporation site for nominal structures obtained from molecular dynamic simulations (MDS).

  15. Ultrasensitivity of Water Exchange Kinetics to the Size of Metal Ion.

    PubMed

    Lee, Yuno; Thirumalai, D; Hyeon, Changbong

    2017-09-13

    Metal ions play a vital role in many biological processes. An important factor in these processes is the dynamics of exchange between ion bound-water molecules and the bulk. Although structural and dynamical properties of labile waters bound to metal ions, such as Na(+) and Ca(2+), can be elucidated using molecular dynamics simulations, direct evaluation of rates of exchange of waters rigidly bound to high charge density Mg(2+), has been elusive. Here, we report a universal relationship, allowing us to determine the water exchange time on metal ions as a function of valence and hydration radius. The proposed relationship, which covers times spanning 14 orders of magnitude, highlights the ultrasensitivity of water lifetime to the ion size, as exemplified by divalent ions, Ca(2+) (∼100 ps) and Mg(2+) (∼1.5 μs). We show that even when structures, characterized by radial distributions are similar, a small difference in hydration radius leads to a qualitatively different (associative or dissociative) mechanism of water exchange. Our work provides a theoretical basis for determination of hydration radius, which is critical for accurately modeling the water dynamics around multivalent ions, and hence in describing all electrostatically driven events such as ribozyme folding and catalysis.

  16. Kafirin adsorption on ion-exchange resins: isotherm and kinetic studies.

    PubMed

    Kumar, Prashant; Lau, Pei Wen; Kale, Sandeep; Johnson, Stuart; Pareek, Vishnu; Utikar, Ranjeet; Lali, Arvind

    2014-08-22

    Kafirin is a natural, hydrophobic and celiac safe prolamin protein obtained from sorghum seeds. Today kafirin is found to be useful in designing delayed delivery systems and coatings of pharmaceuticals and nutraceuticals where its purity is important and this can be obtained by adsorptive chromatography. This study is the first scientific insight into the isotherm and kinetic studies of kafirin adsorption on anion- and cation-exchange resins for practical applications in preparative scale chromatography. Adsorption isotherms of kafirin were determined for five anion- and two cation-exchange resins in batch systems. Isotherm parameters such as maximum binding capacity and dissociation constant were determined from Langmuir isotherm, and adsorptive capacity and affinity constant from Freundlich isotherm. Langmuir isotherm was found to fit the adsorption equilibrium data well. Batch uptake kinetics for kafirin adsorption on these resins was also carried out and critical parameters including the diffusion coefficient, film mass transfer coefficient, and Biot number for film-pore diffusion model were calculated. Both the isotherm and the kinetic parameters were considered for selection of appropriate resin for kafirin purification. UNOsphere Q (78.26 mg/ml) and Toyopearl SP-650M (57.4 mg/ml) were found to offer better kafirin binding capacities and interaction strength with excellent uptake kinetics under moderate operating conditions. With these adsorbents, film diffusion resistance was found to be major governing factor for adsorption (Bi<10 and δ<1). Based on designer objective function, UNOsphere Q was found be best adsorbent for binding of kafirin. The data presented is valuable for designing large scale preparative adsorptive chromatographic kafirin purification systems.

  17. Ion-exchange controls the kinetics of deswelling of polyelectrolyte microgels in solutions of oppositely charged surfactant.

    PubMed

    Nilsson, Peter; Hansson, Per

    2005-12-22

    The kinetics of deswelling of sodium polyacrylate microgels (radius 30-140 microm) in aqueous solutions of dodecyltrimethylammonium bromide is investigated by means of micropipet-assisted light microscopy. The purpose of the study is to test a recent model (J. Phys. Chem. B 2003, 107, 9203) proposing that the rate of the volume change is controlled by the transport of surfactant from the solution to the gel core (ion exchange) via the surfactant-rich surface phase appearing in the gel during the volume transition. Equilibrium swelling characteristics of the gel network in surfactant-free solutions and with various amounts of surfactant present are presented and discussed with reference to related systems. A relationship between gel volume and degree of surfactant binding is determined and used in theoretical predictions of the deswelling kinetics. Experimental data for single gel beads observed during deswelling under conditions of forced convection are presented and compared with model calculations. It is demonstrated that the dependences of the kinetics on initial gel size, the surfactant concentration in the solution, and the liquid flow rate are well accounted for by the model. It is concluded that the deswelling rates of the studied gels are strongly influenced by the mass transport of surfactant between gel and solution (stagnant layer diffusion), but only to a minor extent by the transport through the surface phase. The results indicate that, during the volume transition, swelling equilibrium (network relaxation/transport of water) is established on a relatively short time scale and, therefore, can be treated as independent of the ion-exchange kinetics. Theoretical aspects of the kinetics and mechanisms of surfactant transport through the surface phase are discussed.

  18. A Comprehensive Study of the Solubility, Thermochemistry, Ion Exchange, and Precipitation Kinetics of NO3 Cancrinite and NO3 Sodalite

    SciTech Connect

    Colon, Carlos F. Joyce; Navrotsky, Alexandra; Krumhansl, James L.; Nyman, May

    2003-06-01

    NO3 cancrinite and NO3 sodalite haves been found as a common sodium alumino-silicate forming in strongly caustic alkaline aqueous solutions associated with radioactive High Level Waste (HLW) stored in many underground tanks and also in nuclear waste treatment facilities such as the Savannah River Site (SRS). The precipitation of alumino-silicate phases from caustic nuclear wastes has proven to be problematic in a number of processes in waste treatment facilities including radionuclide separations (cementation of columns by aluminosilicate phases), tank emptying (aluminosilicate tank heels), and condensation of wastes in evaporators (aluminosilicate precipitates in the evaporators, providing nucleation sites for growth of critical masses of radioactive actinide salts). Therefore, in order to prevent their formation an assessment of the relative stability, formation kinetics, and the ion-exchange characteristics of these two phases in HLW solutions needs to be investigated. The goals of this project are to: (1) Develop a robust equilibrium thermodynamic framework to accurately describe and predict the formation of NO3 cancrinite and NO3 sodalite. (2) Provide a comprehensive characterization of the solid precipitation rates and mechanisms using novel spectroscopic (e.g., NMR) and thermochemical techniques in conditions encountered in HLW waste solutions. (3) Characterize the precipitation kinetics of the aluminosilicates and study the effects of temperature and fluid composition. (4) Investigate the ion exchange capacity of these zeolitic phases with respect to radionuclides and RCRA metal species.

  19. Separation of low concentration of cesium ion from wastewater by electrochemically switched ion exchange method: experimental adsorption kinetics analysis.

    PubMed

    Sun, Bin; Hao, Xiao-Gang; Wang, Zhong-De; Guan, Guo-Qing; Zhang, Zhong-Lin; Li, Yi-Bin; Liu, Shi-Bin

    2012-09-30

    A series of experiments were performed to evaluate the continuous separation of cesium based on an electrochemically switched ion exchange (ESIX) process using a diaphragm-isolated reactor with two identical nickel hexacyanoferrate/porous three-dimensional carbon felt (NiHCF/PTCF) electrodes as working electrodes. The effects of applied potential, initial concentrations and pH values of the simulation solutions on the adsorption of cesium ion were investigated. The adsorption rate of cesium ion in the ESIX process was fitted by a pseudo-first-order reaction model. The experiments revealed that the introduction of applied potential on the electrodes greatly enhanced the adsorption/desorption rate of Cs(+) and increased the separation efficiency. H(3)O(+) was found to play a dual role of electrolyte and competitor, and the adsorption rate constant showed a curve diversification with an increase in pH value. Also, it was found that the electrochemically switched adsorption process of Cs(+) by NiHCF/PTCF electrodes proceeded in two main steps, i.e., an ESIX step with a fast adsorption rate and an ion diffusion step with a slow diffusion rate. Meanwhile, the NiHCF/PTCF film electrode showed adsorption selectivity for Cs(+) in preference to Na(+).

  20. Kinetics and equilibrium studies for the removal of nickel and zinc from aqueous solutions by ion exchange resins.

    PubMed

    Alyüz, Bilge; Veli, Sevil

    2009-08-15

    Removal of heavy metals from wastewater is obligatory in order to avoid water pollution. In the present study, performance of Dowex HCR S/S cation exchange resin was evaluated for removal of nickel and zinc from aqueous solutions. Batch shaking adsorption experiments were performed in order to examine the effects of pH, dosage of resin and contact time on removal process. It was observed that more than 98% removal efficiency was achieved under optimal conditions for nickel and zinc. The experimental equilibrium data were tested for the Langmuir, Freundlich and Temkin isotherms. Correlation coefficients indicate the following order to fit isotherms: Langmuir>Freundlich>Temkin for both nickel and zinc ions. Pseudo-first- and -second-order kinetic models were used for describing kinetic data. It was determined that removal of Ni(2+) and Zn(2+) was well-fitted by second-order reaction kinetic. Furthermore, separation factors and distribution coefficients of nickel and zinc for Dowex HCR S/S were calculated.

  1. Arsenic(V) removal using an amine-doped acrylic ion exchange fiber: Kinetic, equilibrium, and regeneration studies.

    PubMed

    Lee, Chang-Gu; Alvarez, Pedro J J; Nam, Aram; Park, Seong-Jik; Do, Taegu; Choi, Ung-Su; Lee, Sang-Hyup

    2017-03-05

    This study investigates As(V) removal from aqueous solutions using a novel amine-doped acrylic ion exchange fiber. The amine doping reaction was confirmed using FT-IR, and the surface of the fiber was characterized using FEG-SEM. The synthesis process was completed within 60min using an AlCl3·6H2O catalyst at 100°C, and the resulting in a fiber with an ion exchange capacity of 7.5meq/g. The removal efficiency of the A-60 fiber was affected by the solution pH, and the efficiency was optimum at pH 3.04. As(V) adsorption on the fiber was rapid in the first 20min and reached equilibrium in 60min. As(V) removal followed pseudo-first-order kinetics, and the Redlich-Peterson adsorption isotherm model provided the best fit of the equilibrium data. The fiber has an As(V) adsorption capacity (qe) of 205.32±3.57mg/g, which is considerably higher than literature values and commercial adsorbents. The removal efficiency of the fiber was above 83% of the initial value after nine regeneration cycles.

  2. A Comprehensive Study of the Solubility, Thermochemistry, Ion Exchange, and Precipitation Kinetics of NO3 Cancrinite and NO3 Sodalite

    SciTech Connect

    Colon, Carlos F. Jove; Navrotsky, Alexandra; Krumhansl, James L.; Nyman, May

    2002-06-01

    NO3 cancrinite and NO3 sodalite haves been found as a common sodium alumino-silicate forming in strongly caustic alkaline aqueous solutions associated with radioactive High Level Waste (HLW) stored in many underground tanks and also in nuclear waste treatment facilities such as the Savannah River Site (SRS). The appearance of these phases have created very expensive problems in waste treatment plants by fouling process evaporators in the SRS waste processing facility. Therefore, in order to prevent their formation an assessment of the relative stability, formation kinetics, and the ion-exchange characteristics of these two phases in HLW solutions needs to be investigated. The goals of this project are to: (1) Develop a robust equilibrium thermodynamic framework to accurately describe and predict the formation of NO3 cancrinite and NO3 sodalite. (2) Provide a comprehensive characterization of the solid precipitation rates and mechanisms using novel spectroscopic (e.g., NMR) and thermochemical techniques in conditions encountered in HLW waste solutions. (3) Investigate the ion exchange capacity of these zeolitic phases with respect to radionuclides and RCRA metal species.

  3. Kinetics of nitrate and perchlorate reduction in ion-exchange brine using the membrane biofilm reactor (MBfR).

    PubMed

    Van Ginkel, Steven W; Ahn, Chang Hoon; Badruzzaman, Mohammad; Roberts, Deborah J; Lehman, S Geno; Adham, Samer S; Rittmann, Bruce E

    2008-09-01

    Several sources of bacterial inocula were tested for their ability to reduce nitrate and perchlorate in synthetic ion-exchange spent brine (30-45 g/L) using a hydrogen-based membrane biofilm reactor (MBfR). Nitrate and perchlorate removal fluxes reached as high as 5.4 g Nm(-2)d(-1) and 5.0 g ClO(4)m(-2)d(-1), respectively, and these values are similar to values obtained with freshwater MBfRs. Nitrate and perchlorate removal fluxes decreased with increasing salinity. The nitrate fluxes were roughly first order in H(2) pressure, but roughly zero-order with nitrate concentration. Perchlorate reduction rates were higher with lower nitrate loadings, compared to high nitrate loadings; this is a sign of competition for H(2). Nitrate and perchlorate reduction rates depended strongly on the inoculum. An inoculum that was well acclimated (years) to nitrate and perchlorate gave markedly faster removal kinetics than cultures that were acclimated for only a few months. These results underscore that the most successful MBfR bioreduction of nitrate and perchlorate in ion-exchange brine demands a well-acclimated inoculum and sufficient hydrogen availability.

  4. Combined Yamamoto approach for simultaneous estimation of adsorption isotherm and kinetic parameters in ion-exchange chromatography.

    PubMed

    Rüdt, Matthias; Gillet, Florian; Heege, Stefanie; Hitzler, Julian; Kalbfuss, Bernd; Guélat, Bertrand

    2015-09-25

    Application of model-based design is appealing to support the development of protein chromatography in the biopharmaceutical industry. However, the required efforts for parameter estimation are frequently perceived as time-consuming and expensive. In order to speed-up this work, a new parameter estimation approach for modelling ion-exchange chromatography in linear conditions was developed. It aims at reducing the time and protein demand for the model calibration. The method combines the estimation of kinetic and thermodynamic parameters based on the simultaneous variation of the gradient slope and the residence time in a set of five linear gradient elutions. The parameters are estimated from a Yamamoto plot and a gradient-adjusted Van Deemter plot. The combined approach increases the information extracted per experiment compared to the individual methods. As a proof of concept, the combined approach was successfully applied for a monoclonal antibody on a cation-exchanger and for a Fc-fusion protein on an anion-exchange resin. The individual parameter estimations for the mAb confirmed that the new approach maintained the accuracy of the usual Yamamoto and Van Deemter plots. In the second case, offline size-exclusion chromatography was performed in order to estimate the thermodynamic parameters of an impurity (high molecular weight species) simultaneously with the main product. Finally, the parameters obtained from the combined approach were used in a lumped kinetic model to simulate the chromatography runs. The simulated chromatograms obtained for a wide range of gradient lengths and residence times showed only small deviations compared to the experimental data. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. H/D exchange kinetics: experimental evidence for formation of different b fragment ion conformers/isomers during the gas-phase peptide sequencing.

    PubMed

    Fattahi, Alireza; Zekavat, Behrooz; Solouki, Touradj

    2010-03-01

    Electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) combined with H/D exchange reactions was utilized to explore the existence of different b(5)(+) and b(4)(+) fragment ion conformers/isomers of hexapeptide WHWLQL in the gas phase. Distinct H/D exchange trends for protonated WHWLQL ([M + H](+)) and its b(5)(+) and b(4)(+) fragment ions (with ND(3)) were observed. Isolated (12)C(all) isotopomers of both b(5)(+) and b(4)(+) fragment ions yielded bimodal distributions of H/D exchanged product ions. The H/D exchange reaction kinetics also confirmed that b(5)(+) and b(4)(+) fragment ions exist as combination of slow-exchanging ("s") and fast-exchanging ("f") species. The calculated rate constant for the first labile hydrogen exchange of [M + H](+) (k([M + H](+)) = 3.80 +/- 0.7 x 10(-10) cm(3) mol(-1) s(-1)) was approximately 30 and approximately 5 times greater than those for the "s" and "f" species of b(5)(+), respectively. Data from H/D exchange of isolated "s" species at longer ND(3) reaction times confirmed the existence of different conformers or isomers for b(5)(+) fragment ions. The sustained off-resonance irradiation collision-activated dissociation (SORI-CAD) of WHWLQL combined with the H/D exchange reactions indicate that "s" and "f" species of b(5)(+) and b(4)(+) fragment ions can be produced in the ICR cell as well as the ESI source. The significance of these observations for detailed understanding of protein sequencing and ion fragmentation pathways is discussed.

  6. Modelling Mixed Bed Ion Exchange Kinetics for Removal of Trace Levels of Divalent Cations in Ultrapure Water

    SciTech Connect

    B. Widman

    2003-01-01

    Ion exchanger resin fluid film mass transfer coefficients and the ionic diffusivities from which they are derived are often measured by use of ion exchange resin columns. Such tests, usually run dynamically using short resin beds, are often performed using relatively high (ppm) concentrations of ions to accurately measure output concentrations as a function of flow rate. The testing described herein was performed to determine fluid film ionic diffusivities for cationic concentrations typical of ultrapure water ({le}ppb levels) containing ppm levels of ammonia. Effective ionic diffusivities at these low ionic concentrations and high pHs were needed to complete a computer model (SIMIX) to be used in ion exchange simulations. SIMIX is a generalized multicomponent ion exchange model designed to simulate the removal of divalent cations from ultrapure water.

  7. The inverse problem of the kinetics of redox sorption taking into account the size of ultradisperse metal particles in an electron-ion exchanger

    NASA Astrophysics Data System (ADS)

    Konev, D. V.; Fertikov, V. V.; Kravchenko, T. A.; Kalinichev, A. I.

    2008-08-01

    The inverse kinetic problem of reducing sorption of molecular oxygen by a copper-containing electron-ion exchanger was formulated and solved taking into account the influence of the size of ultradisperse metal particles on the total rate of the process. These results were used to determine the inside diffusion coefficient of oxygen and rate constants for its interaction with disperse copper from the experimental kinetic curves. The diffusion coefficient obtained was compared with the result of an independent experiment. The kinetic parameters found were used to perform a theoretical analysis of the contributions of various factors influencing the rate of the process under consideration. The reason for the experimentally observed acceleration of the reducing sorption of oxygen by a high-dispersity electron-ion exchanger sample was shown to be an increase in the surface area of metal because of a decrease in the size of its particles and a comparatively high copper content in the surface layer of grains.

  8. Kinetics and equilibrium adsorption studies of dimethylamine (DMA) onto ion-exchange resin.

    PubMed

    Hu, Qinhai; Meng, Yuanyuan; Sun, Tongxi; Mahmood, Qaisar; Wu, Donglei; Zhu, Jianhang; Lu, George

    2011-01-30

    The fine grained resin ZGSPC106 was used to adsorb dimethylamine (DMA) from aqueous solution in the present research. Batch experiments were performed to examine the effects of initial pH of solution and agitation time on the adsorption process. The thermodynamics and kinetics of adsorption were also analyzed. The maximum adsorption was found at natural pH of DMA solution and equilibrium could be attained within 12 min. The equilibrium adsorption data were conformed satisfactorily to the Langmuir equation. The evaluation based on Langmuir isotherm gave the maximal static saturated adsorption capacity of 138.89 mg/g at 293K. Various thermodynamic parameters such as free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) showed that the adsorption was spontaneous, endothermic and feasible. DMA adsorption on ZGSPC106 fitted well to the pseudo-second-order kinetic model. Furthermore, the adsorption mechanism was discussed by Fourier transform infrared spectroscopy (FT-IR) analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. A Comprehensive Study of the Solubility, Thermochemistry, Ion Exchange and Precipitation Kinetics of NO3 Cancrinite and No3 Sodalite

    SciTech Connect

    Jove-Colon, Carlos; Navrotsky, Alexandra

    2004-12-31

    The precipitation of aluminosilicate phases from caustic nuclear wastes has proven to be problematic in a number of processes including radionuclide separations (cementation of columns by aluminosilicate phases), tank emptying (aluminosilicate tank heels), and condensation of wastes in evaporators (aluminosilicate precipitates in the evaporators, providing nucleation sites for growth of critical masses of radioactive actinide salts). In a collaboration between SNL and UCD, we have investigated why and how these phases form, and which conditions favor the formation of which phases. These studies have involved synthesis and characterization of aluminosilicate phases formed using a variety of synthesis techniques, kinetics of precipitation, structural investigations of aluminosilicate phases, thermodynamic calculations of aluminosilicate solubility, calorimetric studies of aluminosilicate precipitation, and a limited investigation of radionuclide partitioning and ion exchange processes (involving typical tank fluid chemistries and these materials). The predominant phases that are observed in the aluminosilicate precipitates from basic tanks wastes (i.e. Hanford, Savannah River Site ''SRS'' wastes) are the salt enclathrated zeolites: sodium nitrate, sodium carbonate and sodium hydroxide sodalite and cancrinite. These phases precipitate readily from the high ionic strength, highly basic solutions at ambient temperatures as well as at elevated temperatures, with or without the presence of an external Al and Si source (both are contained in the waste solutions), and upon interactions with reactive soil components such as clays. This report focuses on the portion of the work performed at UC Davis by Professor Navrotsky's group.

  10. Comprehensive Study of the Solubility, Thermochemistry, Ion Exchange, and Precipitation Kinetics of NO3 Cancrinite and NO33 Sodalite

    SciTech Connect

    Navrotsky, Alexandra; Liu, Qinyuan

    2004-12-01

    The precipitation of aluminosilicate phases from caustic nuclear wastes has proven to be problematic in a number of processes including radionuclide separations (cementation of columns by aluminosilicate phases), tank emptying (aluminosilicate tank heels), and condensation of wastes in evaporators (aluminosilicate precipitates in the evaporators, providing nucleation sites for growth of critical masses of radioactive actinide salts). In a collaboration between SNL and UCD, we have investigated why and how these phases form, and which conditions favor the formation of which phases. These studies have involved synthesis and characterization of aluminosilicate phases formed using a variety of synthesis techniques, kinetics of precipitation, structural investigations of aluminosilicate phases, thermodynamic calculations of aluminosilicate solubility, calorimetric studies of aluminosilicate precipitation, and a limited investigation of radionuclide partitioning and ion exchange processes (involving typical tank fluid chemistries and these materials). The predominant phases that are observed in the aluminosilicate precipitates from basic tanks wastes (i.e. Hanford, Savannah River Site ''SRS'' wastes) are the salt enclathrated zeolites: sodium nitrate, sodium carbonate and sodium hydroxide sodalite and cancrinite. These phases precipitate readily from the high ionic strength, highly basic solutions at ambient temperatures as well as at elevated temperatures, with or without the presence of an external Al and Si source (both are contained in the waste solutions), and upon interactions with reactive soil components such as clays.

  11. Kinetics of esterification of acidified oil with different alcohols by a cation ion-exchange resin/polyethersulfone hybrid catalytic membrane.

    PubMed

    Zhang, Honglei; Ding, Jincheng; Qiu, Yanli; Zhao, Zengdian

    2012-05-01

    Hybrid catalytic membranes consisting of cation ion-exchange resin particles (CERP) and polyethersulfone (PES) were prepared by immersion phase inversion and used as heterogeneous catalysts for the esterification of acidified oil with methanol, ethanol, propanol and butanol. The membranes were characterized by ion exchange capacity and swelling degree tests. The membranes were annealed at different temperatures to improve catalytic activity and membranes annealed at 393 K had the highest catalytic activity. Butanol allowed the highest free fatty acids (FFAs) conversion of 95.28% since it has better miscibility than the other alcohols which strengthened mass and heat transfer. Furthermore, pseudo-homogeneous kinetic models of the esterification of acidified oil with the four alcohols were established according to the experimental data. The kinetic models can well predict the FFA conversion. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Ion exchange phenomena

    SciTech Connect

    Bourg, I.C.; Sposito, G.

    2011-05-01

    Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

  13. A Comprehensive Study of the Solubility, Thermochemistry, Ion Exchange, and Precipitation Kinetics of NO3 Cancrinite and NO3 Sodalite (Project No.: 81959)

    SciTech Connect

    Colon, Carlos F. Jove; Navrotsky, Alexandra; Krumhansl, James L.; Nyman, May; Liu, Qingyuan

    2004-06-01

    NO3 cancrinite and NO3 sodalite haves been found as a common sodium alumino-silicate forming in strongly caustic and alkaline aqueous solutions associated with radioactive High Level Waste (HLW) stored in many underground tanks and also in nuclear waste treatment facilities such as the Savannah River Site (SRS). The appearance of these phases have created very expensive problems in waste treatment plants by fouling process evaporators in the SRS waste processing facility. Therefore, in order to prevent their formation an assessment of the relative stability, formation kinetics, and the ion-exchange characteristics of these two phases in HLW solutions needs to be investigated. The goals of this project are to: (1) Develop a robust equilibrium thermodynamic framework to accurately describe the formation of NO3 cancrinite and NO3 sodalite. (2) Provide quantification and characterization of the solid precipitation rates through long-term batch kinetic experiments and novel analytical techniques. (3) Investigate the partitioning and ion exchange properties of these zeolitic phases with respect to radionuclides and RCRA metal species. This also includes compositional and structural characterization of ion exchanged solids elucidate the exchange properties of these phases.

  14. Kinetics of nitrate and perchlorate reduction in ion exchange brine using the membrane biofilm reactor (MBfR)

    EPA Science Inventory

    Several sources of bacterial inocula were tested for their ability to reduce nitrate and perchlorate in synthetic ion-exchange spent brine (3-4.5% salinity) using a hydrogen-based membrane biofilm reactor (MBfR). Nitrate and perchlorate removal fluxes reached as high as 5.4 g N ...

  15. Kinetics of nitrate and perchlorate reduction in ion exchange brine using the membrane biofilm reactor (MBfR)

    EPA Science Inventory

    Several sources of bacterial inocula were tested for their ability to reduce nitrate and perchlorate in synthetic ion-exchange spent brine (3-4.5% salinity) using a hydrogen-based membrane biofilm reactor (MBfR). Nitrate and perchlorate removal fluxes reached as high as 5.4 g N ...

  16. Kinetics of oxygen exchange between bisulfite ion and water as studied by oxygen-17 nuclear magnetic resonance spectroscopy

    SciTech Connect

    Horner, D.A.

    1984-08-01

    The nuclear magnetic relaxation times of oxygen-17 have been measured in aqueous sodium bisulfite solutions in the pH range from 2.5 to 5 as a function of temperature, pH, and S(IV) concentration, at an ionic strength of 1.0 m. The rate law for oxygen exchange between bisulfite ion and water was obtained from an analysis of the data, and is consistent with oxygen exchange occurring via the reaction SO/sub 2/ + H/sub 2/O right reversible H/sup +/ + SHO/sub 3//sup -/. The value of k/sub -1/ is in agreement with relaxation measurements. Direct spectroscopic evidence was found for the existence of two isomers of bisulfite ion: one with the proton bonded to the sulfur (HSO/sub 3//sup -/) and the other with the proton bonded to an oxygen (SO/sub 3/H/sup -/). (The symbol SHO/sub 3//sup -/ in the above chemical equation refers to both isomeric forms of bisulfite ion.) The relative amounts of the two isomers were determined as a function of temperature, and the rate and mechanism of oxygen exchange between the two was investigated. One of the two isomers, presumably SO/sub 3/H/sup -/, exchanges oxygens with water much more rapidly than does the other. A two-pulse sequence was developed which greatly diminished the solvent peak in the NMR spectrum.

  17. Composite ion exchange materials

    SciTech Connect

    Amarasinghe, S.; Zook, L.; Leddy, J.

    1994-12-31

    Composite ion exchange materials can be formed by sorbing ion exchange polymers on inert, high surface area substrates. In general, the flux of ions and molecules through these composites, as measured electrochemically, increases as the ratio of the surface area of the substrate increases relative to the volume of the ion exchanger. This suggests that fields and gradients established at the interface between the ion exchanger and substrate are important in determining the transport characteristics of the composites. Here, the authors will focus on composites formed with a cation exchange polymer, Nafion, and two different types of microbeads: polystyrene microspheres and polystyrene coated magnetic microbeads. For the polystyrene microbeads, scanning electron micrographs suggest the beads cluster in a self-similar manner, independent of the bead diameter. Flux of Ru(NH3)63+ through the composites was studied as a function of bead fraction, bead radii, and fixed surface area with mixed bead sizes. Flux was well modeled by surface diffusion along a fractal interface. Magnetic composites were formed with columns of magnetic microbeads normal to the electrode surface. Flux of Ru(NH3)63+ through these composites increased exponentially with bead fraction. For electrolyses, the difference in the molar magnetic susceptibility of the products and reactants, Dcm, tends to be non-zero. For seven redox reactions, the ratio of the flux through the magnetic composites to the flux through a Nafion film increases monotonically with {vert_bar}Dcm{vert_bar}, with enhancements as large as thirty-fold. For reversible species, the electrolysis potential through the magnetic composites is 35 mV positive of that for the Nafion films.

  18. Charge exchange molecular ion source

    DOEpatents

    Vella, Michael C.

    2003-06-03

    Ions, particularly molecular ions with multiple dopant nucleons per ion, are produced by charge exchange. An ion source contains a minimum of two regions separated by a physical barrier and utilizes charge exchange to enhance production of a desired ion species. The essential elements are a plasma chamber for production of ions of a first species, a physical separator, and a charge transfer chamber where ions of the first species from the plasma chamber undergo charge exchange or transfer with the reactant atom or molecules to produce ions of a second species. Molecular ions may be produced which are useful for ion implantation.

  19. Rate theory of solvent exchange and kinetics of Li+ - BF4-/PF6- ion pairs in acetonitrile

    SciTech Connect

    Dang, Liem X.; Chang, Tsun-Mei

    2016-09-02

    In this paper, we describe our efforts to apply rate theories in studies of solvent exchange around Li+(aq) and the kinetics of ion pairings in lithium-ion batteries (LIB). We report one of the first computer simulations of the exchange dynamics around hydrated Li+ in acetonitrile (ACN), which is common solvent used in LIBs. We also provide details of the ion-pairing kinetics of Li+-[BF4] and Li+-[PF6] in ACN. Using our polarizable force-field models and employing classical rate theories of chemical reactions, we examine the ACN exchange process between the first and second solvation shells around Li+(aq). We calculate exchange rates using transition state theory and weighted them with transmission coefficients determined by the reactive flux and Impey, Madden, and McDonald approaches and Grote-Hynes theory. We found the relaxation times changed from 180 ps to 4600 ps and from 30 ps to 280 ps for Li+-[BF4] and Li+-[PF6] ion pairs, respectively. These results confirm that the solvent response to the kinetics of ion pairing is significant. Our results also show that, in addition to affecting the free energy of solvation into ACN, the anion type also should significantly influence the kinetics of ion pairing. These results will increase our understanding of the thermodynamic and kinetic properties of LIB systems.

  20. Kinetic study of trichloroethylene combustion on exchanged zeolites catalysts.

    PubMed

    Meyer, C I; Borgna, A; Monzón, A; Garetto, T F

    2011-06-15

    In this paper is presented a kinetic study of the catalytic combustion of trichloroethylene (TCE) over Y-zeolites exchanged with several cations. The catalysts, based on zeolite, were prepared by ion exchange and characterized by means of physico-chemical techniques and then tested under kinetic conditions. The kinetic results obtained were interpreted using kinetic models of power-law type and Eley-Rideal. The results obtained indicate that catalyst Y-Cr is more active than Y-Co catalyst. The greater activity of catalyst exchanged with Cr can be attributed to the higher acidity that presented these catalysts. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. In Situ Tracking Kinetic Pathways of Li + /Na + Substitution during Ion-Exchange Synthesis of LixNa1.5–x VOPO 4 F 0.5

    DOE PAGES

    Park, Young-Uk; Bai, Jianming; Wang, Liping; ...

    2017-08-29

    Ion exchange is a ubiquitous phenomenon central to wide industrial applications, ranging from traditional (bio)chemical separation to the emerging chimie douce synthesis of materials for batteries and other energy applications. The exchange process is complex, involving substitution and transport of different ions under non-equilibrium conditions, and thus difficult to probe, leaving a gap in mechanistic understanding of kinetic exchange pathways toward final products. Herein, we report in situ tracking kinetic pathways of Li+/Na+ substitution during solvothermal ion-exchange synthesis of LixNa1.5-xVOPO4F0.5 (0 ≤ x ≤ 1.5), a promising multi-Li polyanionic cathode for batteries. The real-time observation, corroborated by first-principles calculations, revealsmore » a selective replacement of Na+ by Li+, leading to peculiar Na+/Li+/vacancy orderings in the intermediates. Contradicting the traditional belief of facile topotactic substitution via solid solution reaction, an abrupt two-phase transformation occurs and predominantly governs the kinetics of ion exchange and transport in the 1D polyanionic framework, consequently leading to significant difference of Li stoichiometry and electrochemical properties in the exchanged products. The findings may help to pave the way for rational design of ion exchange synthesis for making new materials.« less

  2. In Situ Tracking Kinetic Pathways of Li(+)/Na(+) Substitution during Ion-Exchange Synthesis of LixNa1.5-xVOPO4F0.5.

    PubMed

    Park, Young-Uk; Bai, Jianming; Wang, Liping; Yoon, Gabin; Zhang, Wei; Kim, Hyungsub; Lee, Seongsu; Kim, Sung-Wook; Looney, J Patrick; Kang, Kisuk; Wang, Feng

    2017-09-13

    Ion exchange is a ubiquitous phenomenon central to wide industrial applications, ranging from traditional (bio)chemical separation to the emerging chimie douce synthesis of materials with metastable structure for batteries and other energy applications. The exchange process is complex, involving substitution and transport of different ions under non-equilibrium conditions, and thus difficult to probe, leaving a gap in mechanistic understanding of kinetic exchange pathways toward final products. Herein, we report in situ tracking kinetic pathways of Li(+)/Na(+) substitution during solvothermal ion-exchange synthesis of LixNa1.5-xVOPO4F0.5 (0 ≤ x ≤ 1.5), a promising multi-Li polyanionic cathode for batteries. The real-time observation, corroborated by first-principles calculations, reveals a selective replacement of Na(+) by Li(+), leading to peculiar Na(+)/Li(+)/vacancy orderings in the intermediates. Contradicting the traditional belief of facile topotactic substitution via solid solution reaction, an abrupt two-phase transformation occurs and predominantly governs the kinetics of ion exchange and transport in the 1D polyanionic framework, consequently leading to significant difference of Li stoichiometry and electrochemical properties in the exchanged products. The findings may help to pave the way for rational design of ion exchange synthesis for making new materials.

  3. Biological Ion Exchanger Resins

    PubMed Central

    Damadian, Raymond; Goldsmith, Michael; Zaner, K. S.

    1971-01-01

    Biological selectivity is shown to vary with medium osmotic strength and temperature. Selectivity reversals occur at 4°C and at an external osmolality of 0.800 indicating that intracellular hydration and endosolvent (intracellular water) structure are important determinants in selectivity. Magnetic resonance measurements of line width by steady-state nuclear magnetic resonance (NMR) indicate a difference in the intracellular water signal of 16 Hz between the K form and Na form of Escherichia coli, providing additional evidence that changes in the ionic composition of cells are accompanied by changes in endosolvent structure. The changes were found to be consistent with the thermodynamic and magnetic resonance properties of aqueous electrolyte solutions. Calculation of the dependence of ion-pairing forces on medium dielectric reinforces the role of endosolvent structure in determining ion exchange selectivity. PMID:4943653

  4. Macroreticular chelating ion-exchangers.

    PubMed

    Hirsch, R F; E Gancher, R; Russo, F R

    1970-06-01

    Two macroreticular chelating ion-exchangers have been prepared and characterized. One contains the iminodiacetate group and the second contains the arsonate group as the ion-exchanging site. The macroreticular resins show selectivities among metal ions similar to those of the commercially available naicroreticular chelating resins. Chromatographie separations on the new resins are rapid and sharp.

  5. Ion exchange technology assessment report

    SciTech Connect

    Duhn, E.F.

    1992-01-01

    In the execution of its charter, the SRS Ion Exchange Technology Assessment Team has determined that ion exchange (IX) technology has evolved to the point where it should now be considered as a viable alternative to the SRS reference ITP/LW/PH process. The ion exchange media available today offer the ability to design ion exchange processing systems tailored to the unique physical and chemical properties of SRS soluble HLW's. The technical assessment of IX technology and its applicability to the processing of SRS soluble HLW has demonstrated that IX is unquestionably a viable technology. A task team was chartered to evaluate the technology of ion exchange and its potential for replacing the present In-Tank Precipitation and proposed Late Wash processes to remove Cs, Sr, and Pu from soluble salt solutions at the Savannah River Site. This report documents the ion exchange technology assessment and conclusions of the task team.

  6. Ion exchange technology assessment report

    SciTech Connect

    Duhn, E.F.

    1992-12-31

    In the execution of its charter, the SRS Ion Exchange Technology Assessment Team has determined that ion exchange (IX) technology has evolved to the point where it should now be considered as a viable alternative to the SRS reference ITP/LW/PH process. The ion exchange media available today offer the ability to design ion exchange processing systems tailored to the unique physical and chemical properties of SRS soluble HLW`s. The technical assessment of IX technology and its applicability to the processing of SRS soluble HLW has demonstrated that IX is unquestionably a viable technology. A task team was chartered to evaluate the technology of ion exchange and its potential for replacing the present In-Tank Precipitation and proposed Late Wash processes to remove Cs, Sr, and Pu from soluble salt solutions at the Savannah River Site. This report documents the ion exchange technology assessment and conclusions of the task team.

  7. Ion-exchange hollow fibers

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Klein, Elias (Inventor)

    1977-01-01

    An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, cross-linked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.

  8. Ion-exchange hollow fibers

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Yen, S. P. S.; Klein, E. (Inventor)

    1976-01-01

    An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, crosslinked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.

  9. Ion-exchange hollow fibers

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Klein, Elias (Inventor)

    1980-01-01

    An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, cross-linked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.

  10. Kinetic models of immediate exchange

    NASA Astrophysics Data System (ADS)

    Heinsalu, Els; Patriarca, Marco

    2014-08-01

    We propose a novel kinetic exchange model differing from previous ones in two main aspects. First, the basic dynamics is modified in order to represent economies where immediate wealth exchanges are carried out, instead of reshufflings or uni-directional movements of wealth. Such dynamics produces wealth distributions that describe more faithfully real data at small values of wealth. Secondly, a general probabilistic trading criterion is introduced, so that two economic units can decide independently whether to trade or not depending on their profit. It is found that the type of the equilibrium wealth distribution is the same for a large class of trading criteria formulated in a symmetrical way with respect to the two interacting units. This establishes unexpected links between and provides a microscopic foundations of various kinetic exchange models in which the existence of a saving propensity is postulated. We also study the generalized heterogeneous version of the model in which units use different trading criteria and show that suitable sets of diversified parameter values with a moderate level of heterogeneity can reproduce realistic wealth distributions with a Pareto power law.

  11. Electrically switched ion exchange

    SciTech Connect

    Lilga, M.A.; Schwartz, D.T.; Genders, D.

    1997-10-01

    A variety of waste types containing radioactive {sup 137}Cs are found throughout the DOE complex. These waste types include water in reactor cooling basins, radioactive high-level waste (HLW) in underground storage tanks, and groundwater. Safety and regulatory requirements and economics require the removal of radiocesium before these wastes can be permanently disposed of. Electrically Switched Ion Exchange (ESIX) is an approach for radioactive cesium separation that combines IX and electrochemistry to provide a selective, reversible, and economic separation method that also produces little or no secondary waste. In the ESIX process, an electroactive IX film is deposited electrochemically onto a high-surface area electrode, and ion uptake and elution are controlled directly by modulating the potential of the film. For cesium, the electroactive films under investigation are ferrocyanides, which are well known to have high selectivities for cesium in concentrated sodium solutions. When a cathode potential is applied to the film, Fe{sup +3} is reduced to the Fe{sup +2} state, and a cation must be intercalated into the film to maintain charge neutrality (i.e., Cs{sup +} is loaded). Conversely, if an anodic potential is applied, a cation must be released from the film (i.e., Cs{sup +} is unloaded). Therefore, to load the film with cesium, the film is simply reduced; to unload cesium, the film is oxidized.

  12. Ion exchange - Simulation and experiment

    NASA Technical Reports Server (NTRS)

    Herrmann, Cal C.; Finn, John E.

    1991-01-01

    A FORTRAN program for simulating multicomponent adsorption by ion-exchange resins was adapted for use as both an ASPEN-callable module and as a free-standing simulator of the ion-exchange bed. Four polystyrene-divinylbenzene sulfonic acid resins have been characterized for three principal ions. It is concluded that a chelating resin appears appropriate as a heavy-metal trap. The same ASPEN-callable module is used to model this resin when Wilson parameters can be obtained.

  13. Ion exchange - Simulation and experiment

    NASA Technical Reports Server (NTRS)

    Herrmann, Cal C.; Finn, John E.

    1991-01-01

    A FORTRAN program for simulating multicomponent adsorption by ion-exchange resins was adapted for use as both an ASPEN-callable module and as a free-standing simulator of the ion-exchange bed. Four polystyrene-divinylbenzene sulfonic acid resins have been characterized for three principal ions. It is concluded that a chelating resin appears appropriate as a heavy-metal trap. The same ASPEN-callable module is used to model this resin when Wilson parameters can be obtained.

  14. The Kinetics of Isotopic Exchange Reactions.

    ERIC Educational Resources Information Center

    Logan, S. R.

    1990-01-01

    Discussed are the kinetic interactions of these chemical processes and the determination of the actual order of such reactions. Included are multiple exchange, catalytic exchange with deuterium, and depletion of the original substrate. (CW)

  15. The Kinetics of Isotopic Exchange Reactions.

    ERIC Educational Resources Information Center

    Logan, S. R.

    1990-01-01

    Discussed are the kinetic interactions of these chemical processes and the determination of the actual order of such reactions. Included are multiple exchange, catalytic exchange with deuterium, and depletion of the original substrate. (CW)

  16. FTIR spectrophotometry, kinetics and adsorption isotherms modeling, ion exchange, and EDX analysis for understanding the mechanism of Cd(2+) and Pb(2+) removal by mango peel waste.

    PubMed

    Iqbal, Muhammad; Saeed, Asma; Zafar, Saeed Iqbal

    2009-05-15

    Mango peel waste (MPW) was evaluated as a new sorbent for the removal of Cd(2+) and Pb(2+) from aqueous solution. The maximum sorption capacity of Cd(2+) and Pb(2+) was found to be 68.92 and 99.05mgg(-1), respectively. The kinetics of sorption of both metals was fast, reaching at equilibrium in 60min. Sorption kinetics and equilibria followed pseudo-second order and Langmuir adsorption isotherm models. FTIR analysis revealed that carboxyl and hydroxyl functional groups were mainly responsible for the sorption of Cd(2+) and Pb(2+). Chemical modification of MPW for blocking of carboxyl and hydroxyl groups showed that 72.46% and 76.26% removal of Cd(2+) and Pb(2+), respectively, was due to the involvement of carboxylic group, whereas 26.64% and 23.74% was due to the hydroxyl group. EDX analysis of MPW before and after metal sorption and release of cations (Ca(2+), Mg(2+), Na(+), K(+)) and proton H(+) from MPW with the corresponding uptake of Cd(2+) and Pb(2+) revealed that the main mechanism of sorption was ion exchange. The regeneration experiments showed that the MPW could be reused for five cycles without significant loss in its initial sorption capacity. The study points to the potential of new use of MPW as an effective sorbent for the removal of Cd(2+) and Pb(2+) from aqueous solution.

  17. Vitrification of ion exchange resins

    DOEpatents

    Cicero-Herman, Connie A.; Workman, Rhonda Jackson

    2001-01-01

    The present invention relates to vitrification of ion exchange resins that have become loaded with hazardous or radioactive wastes, in a way that produces a homogenous and durable waste form and reduces the disposal volume of the resin. The methods of the present invention involve directly adding borosilicate glass formers and an oxidizer to the ion exchange resin and heating the mixture at sufficient temperature to produce homogeneous glass.

  18. Electrically Switched Cesium Ion Exchange

    SciTech Connect

    JPH Sukamto; ML Lilga; RK Orth

    1998-10-23

    This report discusses the results of work to develop Electrically Switched Ion Exchange (ESIX) for separations of ions from waste streams relevant to DOE site clean-up. ESIX combines ion exchange and electrochemistry to provide a selective, reversible method for radionuclide separation that lowers costs and minimizes secondary waste generation typically associated with conventional ion exchange. In the ESIX process, an electroactive ion exchange film is deposited onto. a high surface area electrode, and ion uptake and elution are controlled directly by modulating the potential of the film. As a result, the production of secondary waste is minimized, since the large volumes of solution associated with elution, wash, and regeneration cycles typical of standard ion exchange are not needed for the ESIX process. The document is presented in two parts: Part I, the Summary Report, discusses the objectives of the project, describes the ESIX concept and the approach taken, and summarizes the major results; Part II, the Technology Description, provides a technical description of the experimental procedures and in-depth discussions on modeling, case studies, and cost comparisons between ESIX and currently used technologies.

  19. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E. Philip; Alexandratos, Spiro D.; Gatrone, Ralph C.; Chiarizia, Ronato

    1996-01-01

    An ion exchange resin for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene.

  20. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E. Philip; Alexandratos, Spiro D.; Gatrone, Ralph C.; Chiarizia, Ronato

    1994-01-01

    An ion exchange resin for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene disphosphonic acid with styrene, acrylonitrile and divinylbenzene.

  1. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E.P.; Alexandratos, S.D.; Gatrone, R.C.; Chiarizia, R.

    1994-01-25

    An ion exchange resin is described for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene. 9 figures.

  2. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E.P.; Alexandratos, S.D.; Gatrone, R.C.; Chiarizia, R.

    1996-07-23

    An ion exchange resin is described for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene. 10 figs.

  3. DIVALENT ION EXCHANGE WITH ALKALI

    SciTech Connect

    Bunge, A.L.; Klein, G.; Radke, C.J.

    1980-05-01

    Exchange of hardness ions is important in enhanced oil recovery with chemical additives. In both micellar-polymer and caustic flooding processes, multivalent ions released from rock surfaces can interact with anionic surfactants, rendering them preferentially oil soluble and/or insoluble in water. Because hardness cations are sparingly soluble and precipitate in alkaline solutions, such solutions may be more efficient as surfactant flood preflushes than are softened brines. Multivalent ion precipitation may also occur in alkaline waterflooding. To permit design of such processes, this paper presents a chromatographic theory for simultaneous ion exchange with precipitation of divalent ions. Theoretical effluent histories and concentration profiles are presented for the cases of finite pulses and continuous injection of hydroxide ions into linear cores. Complete capture of the insoluble salt particles is assumed. Results are given for the case of instantaneous equilibration of the solution with the precipitate, as well for the case of complete nonequilibrium, in which the solid precipitate does not redissolve. The efficiency of alklaine preflushing is shown to depend on the exchange isotherm, initial divalent loading of the rock, injected pH and salinity, the solubility product of the precipitated salt, and pulse size. The effect of slug size on complete equilibrium removal of hardness ions is reduced efficiency with increasing size until a critical volume approximating continuous injection is reached. Increasing injected pH and salinity provides a more favorable response. Experimental data for Berea sandstone and an argillaceous sand compare favorably with the proposed theory.

  4. Grafted methylenediphosphonate ion exchange resins

    DOEpatents

    Trochimcznk, Andrzej W.; Gatrone, Ralph C.; Alexandratos, Spiro; Horwitz, E. Philip

    1997-01-01

    An ion exchange resin is disclosed that is comprised of an insoluble copolymer onto which are grafted pendent groups that provide 1.0 to about 10 mmol/g dry weight phosphorous. The pendent groups have the formula ##STR1## wherein R is hydrogen, a cation or mixtures thereof; and R.sup.1 is hydrogen or an C.sub.1 -C.sub.2 alkyl group. The resin also contains zero to about 5 mmol/g dry weight of pendent aromatic sulfonate groups. Processes for making and using an ion exchange resin are also disclosed.

  5. Grafted methylenediphosphonate ion exchange resins

    DOEpatents

    Trochimcznk, Andrzej W.; Gatrone, Ralph C.; Alexandratos, Spiro; Horwitz, E. Philip

    1998-01-27

    An ion exchange resin is disclosed that is comprised of an insoluble copolymer onto which are grafted pendent groups that provide 1.0 to about 10 mmol/g dry weight phosphorous. The pendent groups have the formula ##STR1## wherein R is hydrogen, a cation or mixtures thereof; and R.sup.1 is hydrogen or an C.sub.1 -C.sub.2 alkyl group. The resin also contains zero to about 5 mmol/g dry weight of pendent aromatic sulfonate groups. Processes for making and using an ion exchange-resin are also disclosed.

  6. Grafted methylenediphosphonate ion exchange resins

    DOEpatents

    Trochimcznk, A.W.; Gatrone, R.C.; Alexandratos, S.; Horwitz, E.P.

    1997-04-08

    An ion exchange resin is disclosed that is comprised of an insoluble copolymer onto which are grafted pendent groups that provide 1.0 to about 10 mmol/g dry weight phosphorus. The pendent groups have the formula as shown in the patent wherein R is hydrogen, a cation or mixtures thereof; and R{sup 1} is hydrogen or an C{sub 1}-C{sub 2} alkyl group. The resin also contains zero to about 5 mmol/g dry weight of pendent aromatic sulfonate groups. Processes for making and using an ion exchange resin are also disclosed.

  7. Radiation Studies with Argentine Ion Exchange Material

    SciTech Connect

    Crawford, C.L.

    2002-06-28

    A recent technology exchange between Argentina Nuclear Energy Commission (CNEA) and the US Department of Energy involved vitrification studies of ion exchange resins. Details of the spent ion exchange resins currently stored at two Argentine nuclear power plants, Atucha I and Embalse, have been presented in earlier reports. The present study examines irradiation of simulant samples of ion exchange resins.

  8. Ion Exchange and Liquid Column Chromatography.

    ERIC Educational Resources Information Center

    Walton, Harold F.

    1980-01-01

    Emphasizes recent advances in principles and methodology in ion exchange and chromatography. Two tables list representative examples for inorganic ions and organic compounds. Cites 544 references. (CS)

  9. Ion Exchange and Liquid Column Chromatography.

    ERIC Educational Resources Information Center

    Walton, Harold F.

    1980-01-01

    Emphasizes recent advances in principles and methodology in ion exchange and chromatography. Two tables list representative examples for inorganic ions and organic compounds. Cites 544 references. (CS)

  10. Selective adsorption of Pb (II) over the zinc-based MOFs in aqueous solution-kinetics, isotherms, and the ion exchange mechanism.

    PubMed

    Wang, Lei; Zhao, Xinhua; Zhang, Jinmiao; Xiong, Zhenhu

    2017-06-01

    Two series of metal-organic frameworks (MOFs) with similar formula units but different central metal ions (M) or organic linkers (L), M-BDC (BDC = terephthalate, M = Zn, Zr, Cr, or Fe), or Zn-L (L = imidazolate-2-methyl, BDC, BDC-NH2), were prepared and employed as the receptors for adsorption lead ions. It was found that the Zn-BDC exhibited a much higher adsorption capacity than the other M-BDC series with various metal ions which have very closely low capacities at same conditions. Furthermore, the Zn-L (L = imidazolate-2-methyl, BDC, BDC-NH2) still have highly efficient adsorption capacity of lead ions, although the adsorption capacity varies with different ligand, as well as the adsorption rate and the equilibrium pH of the solution. This significant high adsorption over Zn-L, different from other M-BDC series with various metal ions (Zr, Cr, or Fe), can be explained by ion exchange between the central metal ions of Zn-L and lead ion in solution. Based on the analysis of FT-IR, X-ray diffraction pattern, the nitrogen adsorption isotherms, the zeta potentials, and the results, a plausible adsorption mechanism is proposed. When equivalent Zn-L were added to equal volume of aqueous solution with different concentration of lead ion, the content of zinc ion in the solution increases with the increase of the initial concentration of lead ions. The new findings could provide a potential way to fabricate new metal organic frameworks with high and selective capacities of the heavy metal ions.

  11. Deuterium Exchange Kinetics by NMR.

    ERIC Educational Resources Information Center

    Roper, G. C.

    1985-01-01

    Describes a physical chemistry experiment which allows such concepts as kinetics, catalysis, isotope shifts, coupling constants, and the use of nuclear magnetic resonance (NMR) for quantitative work to be covered in the same exercise. Background information, experimental procedures used, and typical results obtained are included. (JN)

  12. Deuterium Exchange Kinetics by NMR.

    ERIC Educational Resources Information Center

    Roper, G. C.

    1985-01-01

    Describes a physical chemistry experiment which allows such concepts as kinetics, catalysis, isotope shifts, coupling constants, and the use of nuclear magnetic resonance (NMR) for quantitative work to be covered in the same exercise. Background information, experimental procedures used, and typical results obtained are included. (JN)

  13. Ion Kinetics in Silane Plasmas

    DTIC Science & Technology

    1988-02-01

    reaction are determined not only by the chemical reactivity but by the electrical properties of the plasma. Current continuity, impedence match- ing...conventional kinetic theory. Since the chemical and physical properties of the noble-gases vary monotonically down the periods of Mendeleev’s table, one...formation. Most literature with the phrase ion chemistry in its title is concerned only with the properties and reactions of positively charged species

  14. Ion exchange purification of scandium

    DOEpatents

    Herchenroeder, L.A.; Burkholder, H.R.

    1990-10-23

    An improvement in purification of scandium through ion exchange chromatography is disclosed in which the oxidation potential of the eluting solution is altered by the addition of potassium chlorate or ammonium chloride so that removal of contaminants is encouraged. The temperature, pH and concentration of the eluent HEDTA are controlled in order to maintain the scandium in the column while minimizing dilution of the scandium band. Recovery of scandium is improved by pumping dilute scandium over the column prior to stripping the scandium and precipitation. This eliminates the HEDTA ion and other monovalent cations contaminating the scandium band. This method maximizes recovery of scandium while maintaining purity. 2 figs.

  15. Ion exchange purification of scandium

    DOEpatents

    Herchenroeder, Laurie A.; Burkholder, Harvey R.

    1990-10-23

    An improvement in purification of scandium through ion exchange chromatography is disclosed in which the oxidation potential of the eluting solution is altered by the addition of potassium chlorate or ammonium chloride so that removal of contaminants is encouraged. The temperature, pH and concentration of the eluent HEDTA are controlled in order to maintain the scandium in the column while minimizing dilution of the scandium band. Recovery of scandium is improved by pumping dilute scandium over the column prior to stripping the scandium and precipitation. This eliminates the HEDTA ion and other monovalent cations contaminating the scandium band. This method maximizes recovery of scandium while maintaining purity.

  16. Pharmaceutical Applications of Ion-Exchange Resins

    ERIC Educational Resources Information Center

    Elder, David

    2005-01-01

    The historical uses of ion-exchanged resins and a summary of the basic chemical principles involved in the ion-exchanged process are discussed. Specific applications of ion-exchange are provided that include drug stabilization, pharmaceutical excipients, taste-masking agents, oral sustained-release products, topical products for local application…

  17. Pharmaceutical Applications of Ion-Exchange Resins

    ERIC Educational Resources Information Center

    Elder, David

    2005-01-01

    The historical uses of ion-exchanged resins and a summary of the basic chemical principles involved in the ion-exchanged process are discussed. Specific applications of ion-exchange are provided that include drug stabilization, pharmaceutical excipients, taste-masking agents, oral sustained-release products, topical products for local application…

  18. Electrically controlled cesium ion exchange

    SciTech Connect

    Lilga, M.

    1996-10-01

    Several sites within the DOE complex (Savannah River, Idaho, Oak Ridge and Hanford) have underground storage tanks containing high-level waste resulting from nuclear engineering activities. To facilitate final disposal of the tank waste, it is advantageous to separate and concentrate the radionuclides for final immobilization in a vitrified glass matrix. This task proposes a new approach for radionuclide separation by combining ion exchange (IX) and electrochemistry to provide a selective and economic separation method.

  19. Novel silica-based ion exchange resin

    SciTech Connect

    1997-11-01

    Eichrom`s highly successful Diphonixo resin resembles a conventional ion exchange resin in its use of sulfonic acid ligands on a styrene- divinylbenzene matrix. Diphonix resin exhibits rapid exchange kinetics that allow economical operation of ion exchange systems. Unlike conventional resins, Diphonix resin contains chelating ligands that are diphosphonic acid groups that recognize and remove the targeted metals and reject the more common elements such as sodium, calcium and magnesium. This latter property makes Diphonix ideal for many industrial scale applications, including those involving waste treatment. For treatment of low-level, transuranic (TRU) and high- level radioactive wastes, Diphonix`s polystyrene backbone hinders its application due to radiolytic stability of the carbon-hydrogen bonds and lack of compatibility with expected vitrification schemes. Polystyrene-based Diphonix is approximately 60% carbon- hydrogen. In response to an identified need within the Department of Energy for a resin with the positive attributes of Diphonix that also exhibits greater radiolytic stability and final waste form compatibility, Eichrom has successfully developed a new, silica-based resin version of Diphonix. Target application for this new resin is for use in environmental restoration and waste management situations involving the processing of low-level, transuranic and high-level radioactive wastes. The resin can also be used for processing liquid mixed waste (waste that contains low level radioactivity and hazardous constituents) including mixed wastes contaminated with organic compounds. Silica-based Diphonix is only 10% carbon-hydrogen, with the bulk of the matrix silica.

  20. Water softening by combination of ultrasound and ion exchange.

    PubMed

    Entezari, M H; Tahmasbi, M

    2009-03-01

    Ion exchange resin used in this work was styrene-divinylbenzene co-polymer with sulfonic acid group as a strong acid cation resin. This resin is particularly well suited for the removal of water hardness. In water treatment, commonly used softening processes are chemical precipitation and ion exchange. In this study, a combination of ultrasound and ion exchange was applied for reducing the hardness of water. The rate of exchange or kinetics of ion exchange is governed by several parameters. Therefore, important variables such as intensity of ultrasound, amount of resin, concentration of ions and contact time were investigated. The experimental data related to the removal of magnesium and calcium ions were fitted properly with Langmuir model. The kinetic of removal for both ions was pseudo-first-order. In point of mechanism, the internal porous and film diffusion were both effective in the process. The capacity of sorption and the velocity of removal were higher in the presence of ultrasound than control method and this is related to the cavitation process.

  1. Facility produced charge-exchange ions

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.

    1981-01-01

    These facility produced ions are created by charge-exchange collisions between neutral atoms and energetic thruster beam ions. The result of the electron transfer is an energetic neutral atom and an ion of only thermal energy. There are true charge-exchange ions produced by collisions with neutrals escaping from the ion thruster and being charge-exchange ionized before the neutral intercepts the tank wall. The facility produced charge-exchange ions will not exist in space and therefore, represent a source of error where measurements involving ion thruster plasmas and their density are involved. The quantity of facility produced ions in a test chamber with a 30 cm mercury ion thruster was determined.

  2. Using Ion Exchange Chromatography to Separate and Quantify Complex Ions

    ERIC Educational Resources Information Center

    Johnson, Brian J.

    2014-01-01

    Ion exchange chromatography is an important technique in the separation of charged species, particularly in biological, inorganic, and environmental samples. In this experiment, students are supplied with a mixture of two substitution-inert complex ions. They separate the complexes by ion exchange chromatography using a "flash"…

  3. Using Ion Exchange Chromatography to Separate and Quantify Complex Ions

    ERIC Educational Resources Information Center

    Johnson, Brian J.

    2014-01-01

    Ion exchange chromatography is an important technique in the separation of charged species, particularly in biological, inorganic, and environmental samples. In this experiment, students are supplied with a mixture of two substitution-inert complex ions. They separate the complexes by ion exchange chromatography using a "flash"…

  4. Ion Exchange Formation via Sulfonated Bicomponent Nonwovens

    NASA Astrophysics Data System (ADS)

    Stoughton, Hannah L.

    For many years ion exchange resins were used to: remove heavy metals from water, recover materials from wastewater, and eliminate harmful gases from the air. While use of these resin beads dominates the ion exchange industry, the beads have limitations that should be considered when decisions are made to employ them. For instance, officials must balance the inherent zero sum surface area and porosity of the materials. This series of studies investigates the use of bicomponent nonwovens as a base substrate for producing high surface area ion exchange materials for the removal of heavy metal ions. Functionalized materials were produced in a two-step process: (1) PET/PE spunbond bicomponent fibers were fractured completely, producing the high surface area nonwoven to be used as the base ion exchange material, and (2) the conditions for functionalizing the PET fibers of the nonwoven webs were investigated where an epoxy containing monomer was grafted to the surface followed by sulfonation of the monomer. The functionalization reactions of the PET fibers were monitored based on: weight gain, FTIR, TOF-SIMS, and SEM. Ion exchange properties were evaluated using titration and copper ion removal capacity from test solutions. The relationship between web structure and removal efficiency of the metal ions was defined through a comparison of the bicomponent and homocomponent nonwovens for copper ion removal efficiency. The investigation revealed that utilizing the high surface area, fractured bicomponent nonwoven ion exchange materials with capacities comparable to commercially available ion exchange resins could be produced.

  5. [Ion specificity during ion exchange equilibrium in natural clinoptilolite].

    PubMed

    He, Yun-Hua; Li, Hang; Liu, Xin-Min; Xiong, Hai-Ling

    2015-03-01

    Zeolites have been widely applied in soil improvement and environment protection. The study on ion specificity during ion exchange equilibrium is of important significance for better use of zeolites. The maximum adsorption capacities of alkali ions during ion exchange equilibrium in the clinoptilolite showed obvious specificity. For alkali metal ions with equivalent valence, the differences in adsorption capacity increased with the decrease of ionic concentration. These results cannot be well explained by the classical theories including coulomb force, ionic size, hydration, dispersion force, classic induction force and surface complexation. We found that the coupling of polarization effects resulted from the quantum fluctuation of diverse alkali metal ions and electric field near the zeolite surface should be the primary reason for specific ion effect during ion exchange in zeolite. The result of this coupling effect was that the difference in the ion dipole moment increased with the increase of surface potential, which further expanded the difference in the adsorption ability between zeolite surface and ions, resulting in different ion exchange adsorption ability at the solid/liquid interface. Due to the high surface charge density of zeolite, ionic size also played an important role in the distribution of ions in the double diffuse layer, which led to an interesting result that distinct differences in exchange adsorption ability of various alkali metal ions were only detected at high surface potential (the absolute value was greater than 0.2 V), which was different from the ion exchange equilibrium result on the surface with low charge density.

  6. Microsecond pulsed hydrogen/deuterium exchange of electrosprayed ubiquitin ions stored in a linear ion trap.

    PubMed

    Rajabi, Khadijeh

    2015-02-07

    A pulse of D2O vapour on the order of microseconds is allowed to react with the +6 to +9 charge states of ubiquitin confined in a linear ion trap (LIT). Two envelopes of peaks are detected for the ions of ubiquitin, corresponding to the ions that exchange more quickly and more slowly. The deuterium uptake of the protonated sites on ubiquitin ions accounts for the ion population with the fast exchange. The hydrogen/deuterium exchange (HDX) kinetics of ubiquitin ions trapped in the LIT for 200 ms showed comparable structural transitions to those trapped for 300 ms. When ions are trapped for longer, i.e. up to 2000 ms, mainly the slow exchanging ion population is detected. In all experiments the +7 ions exchange the most, suggesting a short distance between the surface protonated sites and nearby charged sites, and concomitantly high accessibility of surface protonated sites towards D2O. The +6 ions are more compact than the +7 ions but have one fewer protonated site, therefore fewer surface availabilities for D2O attack. The data suggest that the +6 ions keep most of their solution-phase contacts intact while the hydrophobic core is slightly interrupted in the +7 ions, possibly due to the exposure of charged His68 that is normally buried in the hydrophobic pocket. The +8 and +9 ions have more protonated sites but are less compact than the +7 ions because of Coulombic repulsion, resulting in a larger distance between the protonated sites and the basic sites. The data indicate that the HDX mechanism of ions with the slower exchange corresponding to the second envelope of peaks is primarily governed via a relay mechanism. The results suggest that the pulsed HDX MS method is sampling a population of ubiquitin ions with a similar backbone fold to the solution.

  7. Ion Exchange and Adsorption of Inorganic Contaminants

    EPA Science Inventory

    In the first part of the chapter, the fundamentals of ion exchange and adsorption processes are explained, with the goal of demonstrating how these principles influence process design for inorganic contaminant removal. In the second part, ion exchange and adsorption processes th...

  8. Titania bound sodium titanate ion exchanger

    DOEpatents

    DeFilippi, Irene C. G.; Yates, Stephen Frederic; Shen, Jian-Kun; Gaita, Romulus; Sedath, Robert Henry; Seminara, Gary Joseph; Straszewski, Michael Peter; Anderson, David Joseph

    1999-03-23

    This invention is method for preparing a titania bound ion exchange composition comprising admixing crystalline sodium titanate and a hydrolyzable titanium compound and, thereafter drying the titania bound crystalline sodium titanate and subjecting the dried titania bound ion exchange composition to optional compaction and calcination steps to improve the physical strength of the titania bound composition.

  9. Ion Exchange and Adsorption of Inorganic Contaminants

    EPA Science Inventory

    In the first part of the chapter, the fundamentals of ion exchange and adsorption processes are explained, with the goal of demonstrating how these principles influence process design for inorganic contaminant removal. In the second part, ion exchange and adsorption processes th...

  10. Ion exchange in the nuclear industry

    SciTech Connect

    Bibler, J.P.

    1990-01-01

    Ion exchange is used in nearly every part of the nuclear fuel cycle -- from the purification of uranium from its ore to the final recovery of uranium and transmutation products. Ion exchange also plays a valuable role in the management of nuclear wastes generated in the fuel cycle.

  11. Ion exchange in the nuclear industry

    SciTech Connect

    Bibler, J.P.

    1990-12-31

    Ion exchange is used in nearly every part of the nuclear fuel cycle -- from the purification of uranium from its ore to the final recovery of uranium and transmutation products. Ion exchange also plays a valuable role in the management of nuclear wastes generated in the fuel cycle.

  12. Ion Exchange Membrane Influence on Ohmic Resistance

    USDA-ARS?s Scientific Manuscript database

    Selection of the proper ion exchange membrane can have a significant influence on bioelectrochemical system (BES) power densities. Because ions move across the membrane to achieve electroneutrality, the ion transport resistance (ohmic loss) needs to be minimized to increase power densities. Ohmic ...

  13. Exchange and reduction of Cu(2+) ions in clinoptilolite.

    PubMed

    Iznaga, I Rodríguez; Petranovskii, V; Fuentes, G Rodríguez; Mendoza, C; Aguilar, A Benítez

    2007-12-15

    The ion-exchange and reduction processes for Cu(2+) ions in clinoptilolite from the Caimanes deposit (Moa, Cuba) were studied at different temperatures. The ion-exchange studies were done to determine the kinetic parameters of Cu(2+) removal from solution by this clinoptilolite modified previously to NH(+)(4) form, and thermodynamic parameters of Cu(2+) elution from zeolite using NH(4)Cl solution. The results show that temperature increase favors the exchange and that it is a reversible process. The external diffusion rate appreciably increases with temperature, while, the internal diffusion coefficient rises relatively little. This means that besides ion exchange other processes (such as precipitation of the low-solubility phase and/or salt adsorption) occur, which cause copper removal from solution and affect the intracrystalline diffusion of the ions. For steric reasons the exchange of [Cu(H(2)O)(6)](2+) ions from a solution must occur with a number of water molecules n smaller than 6 (6 > n > or = 0). Cu(2+) reduction by hydrogen and the formation of Cu-particles in the clinoptilolite were verified. The Cu(2+) reduction mechanism is complex, indirect, and sensitive to reduction temperature; consequently, Cu(+)(n) states intermediate between Cu(2+) and Cu(0) should be present in the reduced samples.

  14. The use of fibrous ion exchangers in gold hydrometallurgy

    NASA Astrophysics Data System (ADS)

    Kautzmann, R. M.; Sampaio, C. H.; Cortina, J. L.; Soldatov, V.; Shunkevich, A.

    2002-10-01

    This article examines a family of ion-exchange fibers, FIBAN, containing primary and secondary amine groups. These ion exchangers have a fiber diameter of 20 40 Μm, high osmotic and mechanic stability, a high rate of adsorption and regeneration, and excellent dynamic characteristics as filtering media. Inparticular, this article discusses the use of FIBAN fibrous ion exchangers in the recovery of gold cyanide andbase-metal cyanides (copper and mercury) from mineral-leaching solutions. The influence of polymer structure and water content on their extraction ability is described, along with key parameters of gold hydrometallurgy such as extraction efficiency, selectivity, pH dependence, gold cyanide loading, kinetics, and stripping.

  15. Ligand Exchange Kinetics of Environmentally Relevant Metals

    SciTech Connect

    Panasci, Adele Frances

    2014-07-15

    The interactions of ground water with minerals and contaminants are of broad interest for geochemists but are not well understood. Experiments on the molecular scale can determine reaction parameters (i.e. rates of ligand exchange, activation entropy, activation entropy, and activation volume) that can be used in computations to gain insight into reactions that occur in natural groundwaters. Experiments to determine the rate of isotopic ligand exchange for three environmentally relevant metals, rhodium (Rh), iron (Fe), and neptunium (Np), are described. Many environmental transformations of metals (e.g. reduction) in soil occur at trivalent centers, Fe(III) in particular. Contaminant ions absorb to mineral surfaces via ligand exchange, and the reversal of this reaction can be dangerous, releasing contaminants into the environment. Ferric iron is difficult to study spectroscopically because most of its complexes are paramagnetic and are generally reactive toward ligand exchange; therefore, Rh(III), which is diamagnetic and less reactive, was used to study substitution reactions that are analogous to those that occur on mineral oxide surfaces. Studies on both Np(V) and Np(VI) are important in their own right, as 237Np is a radioactive transuranic element with a half-life of 2 million years.

  16. Ibuprofen ion-exchange fiber complex: improved dissolution and gastric tolerance based on ion exchange.

    PubMed

    Che, Xin; Wang, Li-hong; Yang, Yang; Yuan, Yue; Wang, Qi-fang; Wang, Yan; Li, San-ming

    2013-05-01

    The purpose of the present study is to develop a novel method to improve the dissolution of water-insoluble drug ibuprofen and the gastric tolerance of this non-steroidal anti-inflammatory drug which has potentially serious gastrointestinal side effects. This method is based on ion exchange of ion-exchange fibers. Water-insoluble drug ibuprofen was dispersed in deionized water, and then the ion-exchange fibers in OH(-) type was immersed in it. Ibuprofen and the active groups of the ion-exchange fibers combined into ion pairs based on the acid-base reaction. This drug carrier did not release drugs in deionized water, but in water solution containing other ions it would release the drugs into the solution by ion exchange. Confirmed by the X-ray diffraction and the scanning electron microscopy, the ibuprofen combined onto the ion-exchange fibers was in a highly molecular level dispersed state. The improved dissolution of ibuprofen ion-exchange fiber complexes is likely to originate from this ibuprofen's highly dispersed state. Due to this, ibuprofen's highly dispersed state, ibuprofen ion-exchange fiber complexes significantly decreases the gastrointestinal side effects of ibuprofen by avoiding the solid ibuprofen's educing. The present study showed that ibuprofen ion-exchange fiber complexes have the two-fold advantages. One is to improve the dissolution of ibuprofen. The other is to decrease the ibuprofen's gastrointestinal toxicity.

  17. Ion Exchange in Glass-Ceramics

    NASA Astrophysics Data System (ADS)

    Beall, George; Comte, Monique; Deneka, Matthew; Marques, Paulo; Pradeau, Philippe; Smith, Charlene

    2016-08-01

    In the past few years ion-exchange in glasses has found a renewed interest with a lot of new development and research in industrial and academic labs and the commercialization of materials with outstanding mechanical properties. These glasses are now widely used in many electronic devices including hand-held displays and tablets. The exchange is generally conducted in a bath of molten salt below the transition temperature of the glass. The exchange at the surface of an alkali ion by a bigger one brings compressive stress at the surface. The mechanical properties are dependent on the stress level at the surface and the depth of penetration of the bigger ion. As compared to glasses, glass-ceramics have the interest to display a wide range of aspects (transparent to opaque) and different mechanical properties (especially higher modulus and toughness). There has been little research on ion-exchange in glass-ceramics. In these materials the mechanisms are much more complex than in glasses because of their polyphasic nature: ion-exchange generally takes place mostly in one phase (crystalline phase or residual glass). The mechanism can be similar to what is observed in glasses with the replacement of an ion by another in the structure. But in some cases this ion-exchange leads to microstructural modifications (for example amorphisation or phase change). This article reviews these ion-exchange mechanisms using several transparent and opaque alumino-silicate glass-ceramics as examples. The effect of the ion exchange in the various glass-ceramics will be described, with particular emphasis on flexural strength.

  18. Porous Ceramic Spheres from Ion Exchange Resin

    NASA Technical Reports Server (NTRS)

    Dynys, Fred

    2005-01-01

    A commercial cation ion exchange resin, cross-linked polystyrene, has been successfully used as a template to fabricate 20 to 50 micron porous ceramic spheres. Ion exchange resins have dual template capabilities. Pore architecture of the ceramic spheres can be altered by changing the template pattern. Templating can be achieved by utilizing the internal porous structure or the external surface of the resin beads. Synthesis methods and chemical/physical characteristics of the ceramic spheres will be reported.

  19. Ion exchanges in apatites for biomedical application.

    PubMed

    Cazalbou, S; Eichert, D; Ranz, X; Drouet, C; Combes, C; Harmand, M F; Rey, C

    2005-05-01

    The modification of the composition of apatite materials can be made by several processes corresponding to ion exchange reactions which can conveniently be adapted to current coatings and ceramics and are an alternative to setting up of new synthesis methods. In addition to high temperature thermal treatments, which can partly or almost totally replace the monovalent OH- anion of stoichiometric hydroxyapatite by any halogen ion or carbonate, aqueous processes corresponding to dissolution-reprecipitation reactions have also been proposed and used. However, the most interesting possibilities are provided by aqueous ion exchange reactions involving nanocrystalline apatites. These apatites are characterised by the existence on the crystal surface of a hydrated layer of loosely bound mineral ions which can be easily exchanged in solution. This layer offers a possibility to trap mineral ions and possibly active molecules which can modify the apatite properties. Such processes are involved in mineralised tissues and could be used in biomaterials for the release of active mineral species.

  20. Fluorine negative ion detachment kinetics

    NASA Technical Reports Server (NTRS)

    Burke, R. R.; Miller, W. J.; Gould, R. K.

    1971-01-01

    A study of the rate of F(-) detachment by O and H atoms via the reactions F(-) + O yields FO + e and F(-) + H yields FH+ e was undertaken using a drift tube to produce F(-) ions at various drift velocities and therefore different ion temperatures. Preliminary mobility measurements of F(-) ions in Ar were made, indicating that ion temperatures in the 300 K to 5000 K range could be achieved; however due to numerous difficulties experienced in obtaining a reliable F(-) ion source, the study could not be completed.

  1. Logarithmic Exchange Kinetics in Monodisperse Copolymeric Micelles

    NASA Astrophysics Data System (ADS)

    García Daza, Fabián A.; Bonet Avalos, Josep; Mackie, Allan D.

    2017-06-01

    Experimental measurements of the relaxation kinetics of copolymeric surfactant exchange for micellar systems unexpectedly show a peculiar logarithmic decay. Several authors use polydispersity as an explanation for this behavior. However, in coarse-grained simulations that preserve microscopic details of the surfactants, we find evidence of the same logarithmic behavior. Since we use a strictly monodisperse distribution of chain lengths such a relaxation process cannot be attributed to polydispersity, but has to be caused by an inherent physical process characteristic of this type of system. This is supported by the fact that the decay is specifically logarithmic and not a power law with an exponent inherited from the particular polydispersity distribution of the sample. We suggest that the degeneracy of the energy states of the hydrophobic block in the core, which is broken on leaving the micelle, can qualitatively explain the broad distribution of energy barriers, which gives rise to the observed nonexponential relaxation.

  2. Adsorption of fluoride, phosphate, and arsenate ions on a new type of ion exchange fiber.

    PubMed

    Ruixia, Liu; Jinlong, Guo; Hongxiao, Tang

    2002-04-15

    A new type of ion exchange fiber for the removal of fluoride, phosphate, and arsenate ions has been developed. A batch adsorption technique for investigating adsorption kinetic and equilibrium parameters and determining pH adsorption edges is applied. It is shown that the adsorption properties of the ion exchange fiber for fluoride, phosphate, and arsenate ions depend on the pH value and anion concentration. The adsorption of arsenate on the sorbent reaches a maximum of 97.9% in the pH value range of 3.5 to 7.0. The adsorption percentage of phosphate is more than 99% in the pH range of 3.0 to 5.5. The adsorption of fluoride on the ion exchange fiber is found to be 90.4% at pH 3.0. The Freundlich model can describe the adsorption equilibrium data of fluoride, arsenate, and phosphate anions. The sorption of the three anions on the ion exchange fiber is a rapid process, and the adsorption kinetic data can be simulated very well by the pseudo-second-order rate equation. The column performance is carried out to assess the applicability of the ion exchange fiber for the removal of fluoride, phosphate, and arsenate ions from synthetic wastewaters with satisfactory removal efficiency. The desorption experiment shows that fluoride ion sorbed by the fiber column can be quantitatively desorbed with 5 mL of 0.50 mol/L NaOH at elution rate of 1 mL/min, and 30 mL of NaOH is necessary for the quantitative recovery of phosphate and arsenate ions.

  3. New mechanism of kinetic exchange interaction induced by strong magnetic anisotropy

    PubMed Central

    Iwahara, Naoya; Chibotaru, Liviu F.

    2016-01-01

    It is well known that the kinetic exchange interaction between single-occupied magnetic orbitals (s-s) is always antiferromagnetic, while between single- and double-occupied orbitals (s-d) is always ferromagnetic and much weaker. Here we show that the exchange interaction between strongly anisotropic doublets of lanthanides, actinides and transition metal ions with unquenched orbital momentum contains a new s-d kinetic contribution equal in strength with the s-s one. In non-collinear magnetic systems, this s-d kinetic mechanism can cause an overall ferromagnetic exchange interaction which can become very strong for transition metal ions. These findings are fully confirmed by DFT based analysis of exchange interaction in several Ln3+ complexes. PMID:27098292

  4. ION EXCHANGE SOFTENING: EFFECTS ON METAL CONCENTRATIONS

    EPA Science Inventory

    A corrosion control pipe loop study to evaluate the effect of ion exchange water softening on metal leaching from household plumbing materials was conducted on two different water qualities having different pH's and hardness levels. The results showed that removing hardness ions ...

  5. ION EXCHANGE SOFTENING: EFFECTS ON METAL CONCENTRATIONS

    EPA Science Inventory

    A corrosion control pipe loop study to evaluate the effect of ion exchange water softening on metal leaching from household plumbing materials was conducted on two different water qualities having different pH's and hardness levels. The results showed that removing hardness ions ...

  6. Inorganic ion exchangers for nuclear waste remediation

    SciTech Connect

    Clearfield, A.; Bortun, A.; Bortun, L.; Behrens, E.

    1997-10-01

    The objective of this work is to provide a broad spectrum of inorganic ion exchangers that can be used for a range of applications and separations involving remediation of groundwater and tank wastes. The authors intend to scale-up the most promising exchangers, through partnership with AlliedSignal Inc., to provide samples for testing at various DOE sites. While much of the focus is on exchangers for removal of Cs{sup +} and Sr{sup 2+} from highly alkaline tank wastes, especially at Hanford, the authors have also synthesized exchangers for acid wastes, alkaline wastes, groundwater, and mercury, cobalt, and chromium removal. These exchangers are now available for use at DOE sites. Many of the ion exchangers described here are new, and others are improved versions of previously known exchangers. They are generally one of three types: (1) layered compounds, (2) framework or tunnel compounds, and (3) amorphous exchangers in which a gel exchanger is used to bind a fine powder into a bead for column use. Most of these exchangers can be regenerated and used again.

  7. In Situ Investigations of Ion Exchange Processes in Microporous Materials

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Parise, J. B.; Hanson, J. C.

    2001-12-01

    The mechanism by which ions exchange in microporous and layered solids, such as zeolites and clays for example, has important implications in areas as diverse as soil fertility and environmental remediation. A detailed characterization of the ion-exchange pathway, the structural consequences of ion exchange and the specific sites involved in the course of exchange, is desirable. A probe that is both time- and structure-sensitive allows resolution of which specific sites are involved, along with the effects of different cation types on the uptake and release of ions. In order to discern the mechanism of ion exchange, it is necessary not only to observe the course of the reaction, which can now be done routinely using energy dispersive X-ray diffraction at synchrotron sources, but also to collect dynamic diffraction data of sufficient quality to allow structure refinement using Rietveld structure refinement techniques. This at present requires the collection of monochromatic data. Tradeoffs between time-resolution, peak-to-background discrimination and structural resolution are often required and depend on the problem at hand. We have developed a number of strategies for in situ ion exchange techniques that probe both structural and kinetic information from dynamic solid media. Examples include investigations of the site-specific ion-exchange mechanism in zeolite LSX using a combination of ex situ and in situ time-resolved synchrotron X-ray powder diffraction, Iterative Target Transformation Factor Analysis (ITTFA) and Rietveld structural refinements. Measurement of competitive ion depletion curves showed that the newly synthesized gallosilicate TsG-1 is more selective for Sr than mineral clinoptilolite, and the structural pathway of Sr-exchange in TsG-1 was monitored by in situ and ex situ synchrotron X-ray powder diffraction. In those cases where full structure refinement is desirable using less than optimal powder diffraction data, we found it necessary to first

  8. 21 CFR 173.20 - Ion-exchange membranes.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ion-exchange membranes. 173.20 Section 173.20 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.20 Ion-exchange membranes. Ion-exchange... ion-exchange membrane is prepared by subjecting a polyethylene base conforming to § 177.1520 of...

  9. 21 CFR 173.20 - Ion-exchange membranes.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ion-exchange membranes. 173.20 Section 173.20 Food... for Food Treatment § 173.20 Ion-exchange membranes. Ion-exchange membranes may be safely used in the processing of food under the following prescribed conditions: (a) The ion-exchange membrane is prepared...

  10. 21 CFR 173.20 - Ion-exchange membranes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ion-exchange membranes. 173.20 Section 173.20 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.20 Ion-exchange membranes. Ion-exchange... ion-exchange membrane is prepared by subjecting a polyethylene base conforming to § 177.1520 of...

  11. 21 CFR 173.20 - Ion-exchange membranes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ion-exchange membranes. 173.20 Section 173.20 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.20 Ion-exchange membranes. Ion-exchange... ion-exchange membrane is prepared by subjecting a polyethylene base conforming to § 177.1520 of...

  12. Kinetic Simulations of Ion Beam Neutralization

    SciTech Connect

    Wang, Joseph

    2010-05-21

    Ion beam emission/neutralization is one of the most fundamental problems in spacecraft plasma interactions and electric propulsion. Although ion beam neutralization is readily achieved in experiments, the understanding of the underlying physical process remains at a rather primitive level. No theoretical or simulation models have convincingly explained the detailed neutralization mechanism, and no conclusions have been reached. This paper presents a fully kinetic simulation of ion beam neutralization and plasma beam propagation and discusses the physics of electron-ion coupling and the resulting propagation of a neutralized mesothermal plasma.

  13. Ion thruster charge-exchange plasma flow

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.; Gabriel, S. B.; Kitamura, S.

    1982-01-01

    The electron bombardment ion thruster has been under development for a number of years and during this time, studies of the plasmas produced by the thrusters and their interactions with spacecraft have been evaluated, based on available data. Due to diagnostic techniques used and facility effects, there is uncertainty as to the reliability of data from these early studies. This paper presents data on the flow of the charge-exchange plasma produced just downstream of the thruster's ion optics. The 'end-effect' of a cylindrical Langmuir probe is used to determine ion density and directed ion velocity. Results are compared with data obtained from a retarding potential analyzer-Faraday cup.

  14. Effect of polyamine reagents on exchange capacity in ion exchangers

    NASA Astrophysics Data System (ADS)

    Petrova, T. I.; Dyachenko, F. V.; Bogatyreva, Yu. V.; Borodastov, A. K.; Ershova, I. S.

    2016-05-01

    Effect of compounds involved in complex reagents is described using Helamin 906H reagent as an example. The working exchange capacity of KU-2-8chs cation exchanger in hydrogen form and Amberlite IRA 900Cl anion exchanger in OH form remained almost unchanged when they were used repeatedly to purify water that contained Helamin 906H reagent; in addition, this capacity was the same upon filtration of water that did not contain this reagent. Leakage of total organic carbon was observed earlier than that of calcium ions upon filtration of the solution through the cation exchanger layer. The test results obtained in industrial conditions indicated that using H-OH filters to purify turbine condensate enables the decrease of the concentration of organic and other impurities therein.

  15. The kinetics of transdermal ethanol exchange.

    PubMed

    Anderson, Joseph C; Hlastala, Michael P

    2006-02-01

    The kinetics of ethanol transport from the blood to the skin surface are incompletely understood. We present a mathematical model to predict the transient exchange of ethanol across the skin while it is being absorbed from the gut and eliminated from the body. The model simulates the behavior of a commercial device that is used to estimate the blood alcohol concentration (BAC). During the elimination phase, the stratum corneum of the skin has a higher ethanol concentration than the blood. We studied the effect of varying the maximum BAC and the absorption rate from the gut on the relationship between BAC and equivalent concentration in the gas phase above the skin. The results showed that the ethanol concentration in the gas compartment always took longer to reach its maximum, had a lower maximum, and had a slower apparent elimination rate than the BAC. These effects increased as the maximum BAC increased. Our model's predictions are consistent with experimental data from the literature. We performed a sensitivity analysis (using Latin hypercube sampling) to identify and rank the importance of parameters. The analysis showed that outputs were sensitive to solubility and diffusivity within the stratum corneum, to stratum corneum thickness, and to the volume of gas in the sampling chamber above the skin. We conclude that ethanol transport through the skin is primarily governed by the washin and washout of ethanol through the stratum corneum. The dynamics can be highly variable from subject to subject because of variability in the physical properties of the stratum corneum.

  16. Modeling of Crystalline Silicotitanate Ion Exchange Columns

    SciTech Connect

    Walker, D.D.

    1999-03-09

    Non-elutable ion exchange is being considered as a potential replacement for the In-Tank Precipitation process for removing cesium from Savannah River Site (SRS) radioactive waste. Crystalline silicotitanate (CST) particles are the reference ion exchange medium for the process. A major factor in the construction cost of this process is the size of the ion exchange column required to meet product specifications for decontaminated waste. To validate SRS column sizing calculations, SRS subcontracted two reknowned experts in this field to perform similar calculations: Professor R. G. Anthony, Department of Chemical Engineering, Texas A&038;M University, and Professor S. W. Wang, Department of Chemical Engineering, Purdue University. The appendices of this document contain reports from the two subcontractors. Definition of the design problem came through several meetings and conference calls between the participants and SRS personnel over the past few months. This document summarizes the problem definition and results from the two reports.

  17. Organic ion exchange resin separation methods evaluation

    SciTech Connect

    Witwer, K.S.

    1998-05-27

    This document describes testing to find effective methods to separate Organic Ion Exchange Resin (OIER) from a sludge simulant. This task supports a comprehensive strategy for treatment and processing of K-Basin sludge. The simulant to be used resembles sludge that has accumulated in the 105KE and 105KW Basins in the 1OOK area of the Hanford Site. The sludge is an accumulation of fuel element corrosion products, organic and inorganic ion exchange materials, canister gasket materials, iron and aluminum corrosion products, sand, dirt, and other minor amounts of organic matter.

  18. Ion exchange tempering of glass ophthalmic lenses.

    PubMed

    Keeney, A H; Duerson, H L

    1975-08-01

    We performed low velocity drop-ball tests using 5/8-, 7/8-, and 1-inch diameter steel balls on ophthalmic crown glass lenses chemically tempered by the ion exchange process. Four representative dioptric strengths (+ 2.50 spherical, - 2.50 spherical, -2.50 cylindrical, and plano) were studied with the isolated lenses mounted, convex side up, on the American National Standards Institute Z80 test block. New ion exchange lenses exhibited a 100 to 350% greater capacity for attenuation of energy from low velocity, large size missiles than matched lenses of similar strength prepared by the conventional heat-treating and air-quenching process.

  19. Cesium-specific phenolic ion exchange resin

    DOEpatents

    Bibler, J.P.; Wallace, R.M.

    1995-08-15

    A phenolic, cesium-specific, cation exchange resin is prepared by neutralizing resorcinol with potassium hydroxide, condensing/polymerizing the resulting intermediate with formaldehyde, heat-curing the resulting polymer to effect cross-linking and grinding it to desired particle size for use. This resin will selectively and efficiently adsorb cesium ions in the presence of a high concentration of sodium ions with a low carbon to cesium ratio. 2 figs.

  20. Cesium-specific phenolic ion exchange resin

    DOEpatents

    Bibler, Jane P.; Wallace, Richard M.

    1995-01-01

    A phenolic, cesium-specific, cation exchange resin is prepared by neutralizing resorcinol with potassium hydroxide, condensing/polymerizing the resulting intermediate with formaldehyde, heat-curing the resulting polymer to effect cross-linking and grinding it to desired particle size for use. This resin will selectively and efficiently adsorb cesium ions in the presence of a high concentration of sodium ions with a low carbon to cesium ratio.

  1. Contamination weeping: A chemical ion exchange model

    SciTech Connect

    Chambers, W.B.; Doughty, D.H.; Jones, H.D.T.; Martinez, S.L.; Bennett, P.C.

    1991-01-01

    Experiments have been conducted to determine the applicability of a chemical ion-exchange model to characterize the problem of nuclear fuel transportation cask contamination and release ( weeping''). Surface charge characteristics of Cr{sub 2}O{sub 3} and stainless steel (304) powders have been measured to determine the potential for ion exchange at metal oxide -- aqueous interfaces. The solubility of pool contaminant Co and Cs electrolytes at varying pH and the adsorption characteristics of these ions on Cr{sub 2}O{sub 3} and stainless steel powders in aqueous slurries have been studied. Experiments show that Co ions do reversibly adsorb on these powder surfaces and, more specifically, that adsorption occurs in the nominal pH range (pH = 4--6) of a boric acid-moderated spent fuel pool. Desorption has been demonstrated to occur at pH {le} 3. Cs ions also have been shown to have an affinity for these surfaces although the reversibility of Cs{sup +} bonding by H{sup +} ion exchange has not been fully demonstrated. These results have significant implications for effective decontamination and coating processes used on nuclear fuel transportation casks. 9 refs., 5 figs., 1 tab.

  2. Thermal Analysis of LANL Ion Exchange Column

    SciTech Connect

    Laurinat, J.E.

    1999-06-16

    This document reports results from an ion exchange column heat transfer analysis requested by Los Alamos National Laboratory (LANL). The object of the analysis is to demonstrate that the decay heat from the Pu-238 will not cause resin bed temperatures to increase to a level where the resin significantly degrades.

  3. Coupled acoustic-gravity field for dynamic evaluation of ion exchange with a single resin bead.

    PubMed

    Kanazaki, Takahiro; Hirawa, Shungo; Harada, Makoto; Okada, Tetsuo

    2010-06-01

    A coupled acoustic-gravity field is efficient for entrapping a particle at the position determined by its acoustic properties rather than its size. This field has been applied to the dynamic observation of ion-exchange reactions occurring in a single resin bead. The replacement of counterions in an ion-exchange resin induces changes in its acoustic properties, such as density and compressibility. Therefore, we can visually trace the advancement of an ion-exchange reaction as a time change in the levitation position of a resin bead entrapped in the field. Cation-exchange reactions occurring in resin beads with diameters of 40-120 microm are typically completed within 100-200 s. Ion-exchange equilibrium or kinetics is often evaluated with off-line chemical analyses, which require a batch amount of ion exchangers. Measurements with a single resin particle allow us to evaluate ion-exchange dynamics and kinetics of ions including those that are difficult to measure by usual off-line analyses. The diffusion properties of ions in resins have been successfully evaluated from the time change in the levitation positions of resin beads.

  4. Determination of an ion exchange constant by the use of a kinetic probe: a new semiempirical kinetic approach involving the effects of 3-F- and 4-F-substituted benzoates on the rate of piperidinolysis of anionic phenyl salicylate in aqueous cationic micelles.

    PubMed

    Yusof, Nor Saadah M; Khan, M Niyaz

    2010-07-06

    Pseudo-first-order rate constants (k(obs)) for the nucleophilic substitution reaction of piperidine (Pip) with ionized phenyl salicylate (PS(-)), obtained at a constant [Pip](T) (= 0.1 M), [PS(-)](T) (= 2 x 10(-4) M), [CTABr](T) (cetyltrimethylammonium bromide), < or = 0.06 M NaOH, and a varying concentration of MX (= 3-FC(6)H(4)CO(2)Na, 3-FBzNa and 4-FC(6)H(4)CO(2)Na, 4-FBzNa), follow the kinetic relationship k(obs) = (k(0) + thetaK(X/S)[MX])/(1 + K(X/S)[MX]) which is derived by the use of the pseudophase micellar (PM) model coupled with an empirical equation. The empirical equation explains the effects of [MX] on CTABr micellar binding constant (K(S)) of PS(-) that occur through X(-)/PS(-) ion exchange. Empirical constants theta and K(X/S) give the parameters F(X/S) and K(X/S), respectively. The magnitude of F(X/S) gives the measure of the fraction of micellized PS(-) transferred to the aqueous phase by the limiting concentration of X(-) through X(-)/PS(-) ion exchange. The values of F(X/S) and K(X/S) have been used to determine the usual thermodynamic ion exchange constant (K(X)(Y)) for ion exchange process X(-)/Y(-) on the CTABr micellar surface. The values of K(X)(Br) (where Br = Y) have been calculated for X = 3-FBzNa and 4-FBzNa. The mean values of K(X)(Br) are 12.8 +/- 0.9 and 13.4 +/- 0.6 for X(-) = 3-FBz(-) and 4-FBz(-), respectively. Nearly 3-fold-larger values of K(X)(Br) for X = 3-FBz(-) and 4-FBz(-) than those for X = Bz(-), 2-ClBz(-), 2-CH(3)Bz(-), and the 2,6-dichlorobenzoate ion (2,6-Cl(2)Bz(-)) are attributed to the presence of wormlike micelles in the presence of > 50 mM 3-FBz(-) and 4-FBz(-) in the [CTABr](T) range of 5-15 mM. Rheological properties such as shear thinning behavior of plots of shear viscosity versus the shear rate at a constant [3-FBz(-)] or [4-FBz(-)] as well as shear viscosity (at a constant shear rate) maxima as a function of the concentrations of 3-FBz(-) and 4-FBz(-) support the conclusion, derived from the values of K

  5. Liquid membrane coated ion-exchange column solids

    DOEpatents

    Barkey, Dale P.

    1989-01-01

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

  6. Liquid membrane coated ion-exchange column solids

    DOEpatents

    Barkey, Dale P.

    1988-01-01

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

  7. An Empirical Formula From Ion Exchange Chromatography and Colorimetry.

    ERIC Educational Resources Information Center

    Johnson, Steven D.

    1996-01-01

    Presents a detailed procedure for finding an empirical formula from ion exchange chromatography and colorimetry. Introduces students to more varied techniques including volumetric manipulation, titration, ion-exchange, preparation of a calibration curve, and the use of colorimetry. (JRH)

  8. An Empirical Formula From Ion Exchange Chromatography and Colorimetry.

    ERIC Educational Resources Information Center

    Johnson, Steven D.

    1996-01-01

    Presents a detailed procedure for finding an empirical formula from ion exchange chromatography and colorimetry. Introduces students to more varied techniques including volumetric manipulation, titration, ion-exchange, preparation of a calibration curve, and the use of colorimetry. (JRH)

  9. ION EXCHANGE ADSORPTION PROCESS FOR PLUTONIUM SEPARATION

    DOEpatents

    Boyd, G.E.; Russell, E.R.; Taylor, M.D.

    1961-07-11

    Ion exchange processes for the separation of plutonium from fission products are described. In accordance with these processes an aqueous solution containing plutonium and fission products is contacted with a cation exchange resin under conditions favoring adsorption of plutonium and fission products on the resin. A portion of the fission product is then eluted with a solution containing 0.05 to 1% by weight of a carboxylic acid. Plutonium is next eluted with a solution containing 2 to 8 per cent by weight of the same carboxylic acid, and the remaining fission products on the resin are eluted with an aqueous solution containing over 10 per cent by weight of sodium bisulfate.

  10. Coexistence of ferromagnetism and singlet superconductivity via kinetic exchange.

    PubMed

    Cuoco, Mario; Gentile, Paola; Noce, Canio

    2003-11-07

    We propose a novel mechanism for the coexistence of metallic ferromagnetism and singlet superconductivity assuming that the magnetic instability is due to kinetic exchange. Within this scenario, the unpaired electrons which contribute to the magnetization have a positive feedback on the gain of the kinetic energy in the coexisting phase by undressing the effective mass of the carriers involved in the pairing. The evolution of the magnetization and pairing amplitude and the phase diagram are first analyzed for a generic kinetic exchange model and then are determined within a specific case with spin dependent bond-charge occupation.

  11. Ferric ion-specific sequestering agents. 7. Synthesis, iron-exchange kinetics, and stability constants of N-substituted, sulfonated catechoylamide analogs of enterobactin

    SciTech Connect

    Pecoraro, Vincent L.; Weit, Frederick L.; Raymond, Kenneth N.

    1981-08-01

    For treatment of chronic iron overload (as occurs in Cooley's anemia), ferric ion sequestering agents with specific properties are necessary. Two analogues of enterobactin [a microbial chelating agent with the greatest stability constant known for an Fe(III) complex] are reported which exhibit: i) hydrolytic stability; ii) water solubility; iii) N-substitution to block peptidase hydrolysis. The first compound, N,N',N"- trimethyl-N,N',N"-tris(2,3-dihydroxysulfobenzoyl)1,3,5-triaminomethyl- benzene, [Me3MECAMS, 6] was prepared from the amide of trimesloyl chloride (1) and MeNH2. The resulting amide was reduced to the triamine (3) and converted in three steps to the final product 6 in 6% overall yield. The proton-dependent formation constant (log K*) for the reaction: Fe3+ + H3L6- = FeL6- + 3H+ is 4.87, which gives an equilibrium concentration of [Fe3+] at pH 7.4 of 2 x 10-27 M for 10-5 M L (6) and 10-6 M total Fe3+. The estimated formation constant (log β110) is 40. At low pH the FeL6- complex undergoes a series of three, one-proton reactions which probably gives a tris-salicylate complex formed by the carbonyl and ortho-catechol oxygen of the 2,3-dihydroxybenzoyl units (the same reaction that occurs with ferric enterobactin). After six hours in the presence of 6 mM ascorbate, Me3MECAMS (6.0 mM) removed 3.7% of the ferric ion initially sequestered by the iron storage protein, ferritin. The human iron transport protein transferrin gives up iron to Me3MECAMS with a pseudo first-order rate constant of 1.9 x 10-3min-1 (ligand concentration 2 X 10-4 M). This rate is comparable to that of enterobactin and other catechoyl amide sequestering agents, and greatly exceeds that of desferrioxamine B (Desferal®), the current drug of choice in treating iron overload. Two

  12. Porous solid ion exchange wafer for immobilizing biomolecules

    DOEpatents

    Arora, Michelle B.; Hestekin, Jamie A.; Lin, YuPo J.; St. Martin, Edward J.; Snyder, Seth W.

    2007-12-11

    A porous solid ion exchange wafer having a combination of a biomolecule capture-resin and an ion-exchange resin forming a charged capture resin within said wafer. Also disclosed is a porous solid ion exchange wafer having a combination of a biomolecule capture-resin and an ion-exchange resin forming a charged capture resin within said wafer containing a biomolecule with a tag. A separate bioreactor is also disclosed incorporating the wafer described above.

  13. Charge exchange lifetimes for ions in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Bewtra, N. K.

    1977-01-01

    Latest and best measurements of physical quantities involved in complete calculation of the charge exchange lifetime of mirroring magnetospheric ions are coalesced and summarized. It is critical that the charge exchange lifetimes for ions be known as accurately as possible in order to apply the charge exchange mechanism to ion phenomena within the earth's magnetosphere.

  14. 21 CFR 173.21 - Perfluorinated ion exchange membranes.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Perfluorinated ion exchange membranes. 173.21... Polymer Adjuvants for Food Treatment § 173.21 Perfluorinated ion exchange membranes. Substances identified in paragraph (a) of this section may be safely used as ion exchange membranes intended for use in...

  15. 21 CFR 173.25 - Ion-exchange resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ion-exchange resins. 173.25 Section 173.25 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.25 Ion-exchange resins. Ion-exchange resins may be safely used in the treatment of food under the following prescribed conditions: (a) The...

  16. 21 CFR 173.21 - Perfluorinated ion exchange membranes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Perfluorinated ion exchange membranes. 173.21... ion exchange membranes. Substances identified in paragraph (a) of this section may be safely used as ion exchange membranes intended for use in the treatment of bulk quantities of liquid food under...

  17. 21 CFR 173.21 - Perfluorinated ion exchange membranes.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Perfluorinated ion exchange membranes. 173.21... ion exchange membranes. Substances identified in paragraph (a) of this section may be safely used as ion exchange membranes intended for use in the treatment of bulk quantities of liquid food under...

  18. 21 CFR 173.21 - Perfluorinated ion exchange membranes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Perfluorinated ion exchange membranes. 173.21... ion exchange membranes. Substances identified in paragraph (a) of this section may be safely used as ion exchange membranes intended for use in the treatment of bulk quantities of liquid food under...

  19. 21 CFR 173.21 - Perfluorinated ion exchange membranes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Perfluorinated ion exchange membranes. 173.21... ion exchange membranes. Substances identified in paragraph (a) of this section may be safely used as ion exchange membranes intended for use in the treatment of bulk quantities of liquid food under...

  20. Evaluation of Elution Parameters for Cesium Ion Exchange Resins

    SciTech Connect

    Burgeson, Ingrid E.; Deschane, Jaquetta R.; Cook, Bryan J.; Blanchard, David L.; Weier, Dennis R.

    2006-08-28

    Cesium ion exchange is one of the planned processes for treating and disposing of waste at the U.S. Department of Energy Hanford Site. Radioactive supernatant liquids from the waste tanks will undergo ultrafiltration, followed by cesium ion exchange using a regenerable organic ion exchange resin. Two resins, SuperLig?644 and a Resorcinol-formaldehyde resin are being evaluated for cesium removal and cesium elution characteristics. The main purpose of this study is to optimize the cesium elution to provide a resin which after undergoing elution would meet the U.S. Department of Energy/Office of River Protection Project-Waste Treatment Plant processing and resin disposal criteria. Columns of each resin type were loaded to greater or equal to 90% breakthrough with a Hanford waste stimulant and eluted with nitric acid. The temperature, flow rate and nitric acid concentration were varied to determine the optimal elution conditions. Temperature and eluant flow rate were the most important elution parameters. As would be predicted based upon kinetic consideration alone, decreasing the eluant flow rate and increasing the temperature provided the optimal elution conditions. Varying the nitric acid concentration did not have a significant effect on the elution; however, elutions performed using both high acid concentration (1M) and elevated temperature (45 C) resulted in resin degradation, causing gas generation and resin bed disruption.

  1. Cesium and strontium ion specific exchangers

    SciTech Connect

    Yates, S.

    1996-10-01

    This work is one of two parallel projects that are part of an ESP task to develop high-capacity, selective, solid extractants for cesium, strontium, and technetium from nuclear wastes. In this subtask, Pacific Northwest National Laboratory (PNNL) is collaborating with AlliedSignal, Inc. (Des Plaines, Illinois) to develop inorganic ion exchangers that are selective for strontium and cesium from alkaline high-level waste and groundwater streams.

  2. PRTR ion exchange vault water removal

    SciTech Connect

    Ham, J.E.

    1995-11-01

    This report documents the removal of radiologically contaminated water from the Plutonium Recycle Test Reactor (PRTR) ion exchange vault. Approximately 57,000 liters (15,000 gallons) of water had accumulated in the vault due to the absence of a rain cover. The water was removed and the vault inspected for signs of leakage. No evidence of leakage was found. The removal and disposal of the radiologically contaminated water decreased the risk of environmental contamination.

  3. Cellulosic ion-exchange membranes for hemodialysis.

    PubMed

    Mollison, A N; Graydon, W F

    1977-07-01

    The application of cellulosic ion-exchange membranes to hemodialysis was studied in vitro. The membranes were prepared by radiation-grafting methacrylic acid and vinylpyridine to films of DuPont cellophane PD-215 to produce cation-exchange and anion-exchange membranes, respectively. Solutions of urea, creatinine, glucose, and uric acid were studied for their interactions with and diffusion through the membranes. Ultrafiltration rates were also determined. Cuprophane and PD-215 cellophane were studied as controls. Dialysis plots for the membranes revealed a mechanism of "assisted transport." Initially, the solutes were removed from solution by a sorption/adsorption mechanism followed by a steady-state diffusion process. The calculated diffusivities for these later steady-state regions increased linearly with capacity for urea, creatinine, and uric acid, while for glucose the reverse was true. The combined processes involved provided considerably greater mass transport per unit thickness than either DuPont PD-215 cellophane or Cupropane.

  4. Ion-exchange chromatographic protein refolding.

    PubMed

    Freydell, Esteban J; van der Wielen, Luuk; Eppink, Michel; Ottens, Marcel

    2010-11-12

    The application of ion-exchange (IEX) chromatography to protein refolding (IExR) has been successfully proven, as supported by various studies using different model proteins, ion-exchange media and flow configurations. Ion-exchange refolding offers a relatively high degree of process intensification, represented by the possibility of performing protein refolding, product purification and product concentration, in one unit operation. Besides its high degree of process intensification, IExR offers an additional set of key advantages including: spatial isolation of the bound protein molecules and the controllable change in chemical composition using gradients. Despite of the acknowledgement of the former advantages, the lack of mechanistic understanding on how they influence the process performance of the ion-exchange refolding reactor, limits the ability to exploit them in order to optimize the performance of the unit. This paper presents a quantitative analysis that assesses the effect that the spatial isolation and the urea gradient, have on the IExR performance, judged on the basis of the refolding yield (Y(N)) and the fractional mass recovery (f(Prot,Rec)). Additionally, this work discusses the effect of the protein load, the protein loading state (i.e., native, denatured, denatured and reduced (D&R)) and the adsorbent type on f(Prot,Rec). The presented work shows: (1) that the protein load has a direct effect on f(Prot,Rec), and the magnitude of this effect depends on the loading state of the protein solution and the adsorbent type; (2) that irrespectively of the type of adsorbent used, the saturation capacity of a denatured protein is less than the native protein and that this difference can be linked to differences in accessible binding surface area; (3) that there is a clear correlation between fractional surface coverage (θ) and f(Prot,Rec), indicating that the former could serve as a good descriptor to assess spatial isolation, and (4) that the urea

  5. Features of ion transport in perfluorinated ion-exchange membranes

    SciTech Connect

    Timashev, S.F.

    1986-02-01

    The conditions for functioning for various systems and devices electrolyzers for ''chlorate'' electrolysis, current sources, etc.) with perfluorinated ion-exchange membranes and septums are determined to a considerable degree by the physicochemical properties of the perfluorinated materials. In this work, on the basis of concepts developed in streaming theory as to the topology of the ''infinite clusters'' (ICs), the author defines more precisely the form of the preexponential dependence of ion transport coefficients and draws conclusions on the character of heat evolution in a perfluorinated membrane when an electric current is passed through the membrane.

  6. Ion Exchange Kinetics Testing with SRF Resin

    SciTech Connect

    Russell, Renee L.; Rinehart, Donald E.; Brown, Garrett N.; Schonewill, Philip P.; Peterson, Reid A.

    2012-04-01

    The U.S. Department of Energy (DOE) Hanford Site contains more than 53 million gallons of legacy waste generated as a byproduct of plutonium production and reprocessing operations. The wastes are a complex mixture composed mostly of NaNO3, NaNO2, NaOH, NaAlO2, Na3PO4, and Na2SO4, with a number of minor and trace metals, organics, and radionuclides stored in underground waste tanks. The DOE Office of River Protection (ORP) has contracted Bechtel National Incorporated (BNI) to build a pretreatment facility, the River Protection Project-Waste Treatment Plant (RPP-WTP), that will separate long-lived transuranics (TRU) and highly radioactive components (specifically 137Cs and, in selected cases, 90Sr) from the bulk (non-radioactive) constituents and immobilize the wastes by vitrification. The plant is designed to produce two waste streams: a high-volume low-activity waste (LAW) and a low-volume high-activity waste (HLW).

  7. Quantification of Transthyretin Kinetic Stability in Human Plasma Using Subunit Exchange

    PubMed Central

    2015-01-01

    The transthyretin (TTR) amyloidoses are a group of degenerative diseases caused by TTR aggregation, requiring rate-limiting tetramer dissociation. Kinetic stabilization of TTR, by preferential binding of a drug to the native tetramer over the dissociative transition state, dramatically slows the progression of familial amyloid polyneuropathy. An established method for quantifying the kinetic stability of recombinant TTR tetramers in buffer is subunit exchange, in which tagged TTR homotetramers are added to untagged homotetramers at equal concentrations to measure the rate at which the subunits exchange. Herein, we report a subunit exchange method for quantifying the kinetic stability of endogenous TTR in human plasma. The subunit exchange reaction is initiated by the addition of a substoichiometric quantity of FLAG-tagged TTR homotetramers to endogenous TTR in plasma. Aliquots of the subunit exchange reaction, taken as a function of time, are then added to an excess of a fluorogenic small molecule, which immediately arrests further subunit exchange. After binding, the small molecule reacts with the TTR tetramers, rendering them fluorescent and detectable in human plasma after subsequent ion exchange chromatography. The ability to report on the extent of TTR kinetic stabilization resulting from treatment with oral tafamidis is important, especially for selection of the appropriate dose for patients carrying rare mutations. This method could also serve as a surrogate biomarker for the prediction of the clinical outcome. Subunit exchange was used to quantify the stabilization of WT TTR from senile systemic amyloidosis patients currently being treated with tafamidis (20 mg orally, once daily). TTR kinetic stability correlated with the tafamidis plasma concentration. PMID:24661308

  8. 25th anniversary article: Ion exchange in colloidal nanocrystals.

    PubMed

    Gupta, Shuchi; Kershaw, Stephen V; Rogach, Andrey L

    2013-12-23

    We review the progress in ion exchange in a variety of nanocrystal structures from the earliest accounts dating back over two decades ago to the present day. In recent years the number of groups using this method to form otherwise difficult or inaccessible nanoparticle shapes and morphologies has increased considerably and the field has experienced a resurgence of interest. Whilst most of the early work on cation exchange centered on II-VI materials, the methodology has been expanded to cover a far broader range of semiconductor nanocrystals including low toxicity I-III-VI materials and the much less facile III-V materials. The extent of exchange can be controlled leading to lightly doped nanoparticles, alloys, core-shells, segmented rods and dots-in-rods. Progress has been driven by a better understanding of the underlying principles of the exchange process - from thermodynamic factors (differences in cation solubilities); the interactions between ions and transfer agents (solvents, ligands, anions, co-dopants); ionic in-diffusion mechanisms and kinetics. More recent availability of very detailed electron microscopy coupled with image reconstruction techniques has been a valuable tool to investigate the resulting heterostructures and internal interfaces. We start by surveying the range of synthetic approaches most often used to carry out ion exchange, mainly focusing on cation replacement strategies, and then describe the rich variety of nanostructures these techniques can bring forth. We also describe some of the principles that are used to establish the relative ease of exchange and to systematically improve the process where the basic energetics are less favorable. To help further the understanding of the underlying fundamentals we have gathered together useful data from the literature on solubilities, cation and anion hardness, ligand and solvent Lewis acid or base strengths for a wide range of chemical species generally used. We offer a perspective on the

  9. Simulating complex ion channel kinetics with IonChannelLab

    PubMed Central

    Covarrubias, Manuel; Sánchez-Rodríguez, Jorge E; Perez-Cornejo, Patricia; Arreola, Jorge

    2010-01-01

    In-silico simulation based on Markov chains is a powerful way to describe and predict the activity of many transport proteins including ion channels. However, modeling and simulation using realistic models of voltage- or ligand-gated ion channels exposed to a wide range of experimental conditions require building complex kinetic schemes and solving complicated differential equations. To circumvent these problems, we developed IonChannelLab a software tool that includes a user-friendly Graphical User Interface and a simulation library. This program supports channels with Ohmic or Goldman-Hodgkin-Katz behavior and can simulate the time-course of ionic and gating currents, single channel behavior and steady-state conditions. The program allows the simulation of experiments where voltage, ligand and ionic concentration are varied independently or simultaneously. PMID:20935453

  10. Anion exchangers with branched functional ion exchange layers of different hydrophilicity for ion chromatography.

    PubMed

    Shchukina, O I; Zatirakha, A V; Smolenkov, A D; Nesterenko, P N; Shpigun, O A

    2015-08-21

    Novel polystyrene-divinylbenzene (PS-DVB) based anion exchangers differing from each other in the structure of the branched functional ion exchange layer are prepared to investigate the role of linker and functional site on ion exchange selectivity. The proposed method of synthesis includes the obtaining of aminated PS-DVB particles by means of their acylation with following reductive amination with methylamine. Further modification of the obtained secondary aminogroups is provided by the alkylation with either 1,4-butanediol diglycidyl ether (1,4-BDDGE) or resorcinol diglycidyl ether (RDGE), which form the linkers of different hydrophobicity, and amination of terminal epoxide rings with trimethylamine (TMA), dimethylethanolamine (DMEA), methyldiethanolamine (MDEA) or triethanolamine (TEA). The variation of the structure and hydrophobicity of the linker and terminal quaternary ammonium sites in the functional layer allows the alteration of selectivity and separation efficiency of the obtained adsorbents. The ion exchange selectivity and separation efficiency of the anion exchangers are evaluated using the model mixtures of anions (F(-), HCOO(-), Cl(-), NO2(-), Br(-), NO3(-), HPO4(2-) and SO4(2-)) in potassium hydroxide eluents. The adsorbents show the decrease of selectivity with increasing the hydrophilicity of the terminal functional site. The anion exchangers having more flexible and hydrophilic 1,4-BDDGE linker provide smaller separation factors for most of the analytes as compared with RDGE-containing adsorbents with the same terminal ion exchange sites, but are characterized with higher column efficiencies and better peak symmetry for polarizable anions. In case of 1,4-BDDGE-modified anion exchangers of the particle size of 3.3μm functionalized with DMEA and MDEA the calculated values of column efficiencies for polarizable NO3(-) and Br(-) are up to 49,000 and 53,000N/m, respectively, which is almost twice higher than the values obtained for the RDGE

  11. Ion exchange in hydroxyapatite with lanthanides.

    PubMed

    Cawthray, Jacqueline F; Creagh, A Louise; Haynes, Charles A; Orvig, Chris

    2015-02-16

    Naturally occurring hydroxyapatite, Ca5(PO4)3(OH) (HAP), is the main inorganic component of bone matrix, with synthetic analogues finding applications in bioceramics and catalysis. An interesting and valuable property of both natural and synthetic HAP is the ability to undergo cationic and anionic substitution. The lanthanides are well-suited for substitution for the Ca(2+) sites within HAP, because of their similarities in ionic radii, donor atom requirements, and coordination geometries. We have used isothermal titration calorimetry (ITC) to investigate the thermodynamics of ion exchange in HAP with a representative series of lanthanide ions, La(3+), Sm(3+), Gd(3+), Ho(3+), Yb(3+) and Lu(3+), reporting the association constant (Ka), ion-exchange thermodynamic parameters (ΔH, ΔS, ΔG), and binding stoichiometry (n). We also probe the nature of the La(3+):HAP interaction by solid-state nuclear magnetic resonance ((31)P NMR), X-ray diffraction (XRD), and inductively coupled plasma-optical emission spectroscopy (ICP-OES), in support of the ITC results.

  12. Synthesis and ion-exchange properties of lanthanum tungstate, a new inorganic ion exchanger

    SciTech Connect

    Husain, S.W.; Rasheedzad, S.; Manzoori, J.L.; Jabbari, Y.

    1982-01-01

    Amorphous samples of a new inorganic ion exchanger, lanthanum tungstate, have been prepared under varying conditions. The material prepared by mixing 0.05 M lanthanum nitrate and 0.05 M sodium tungstate in a ratio of 1:2 was studied in detail for its ion-exchange capacity, chemical stability, ir, thermogravimetry, and K/sub d/ values. Its columns have been used for the separation of C/sup 2 +/ from Pd/sup 2 +/, Mn/sup 2 +/, and Cu/sup 2 +/, and Ni/sup 2 +/ from Pd/sup 2 +/. 3 figures, 4 tables.

  13. Analysis of proton exchange kinetics with time-dependent exchange rate.

    PubMed

    Rutkowska-Wlodarczyk, Izabela; Kierdaszuk, Borys; Wlodarczyk, Jakub

    2010-04-01

    Mass spectrometry is used to probe the kinetics of hydrogen-deuterium exchange in lysozyme in pH 5, 6 and 7.4. An analysis based on a Verhulst growth model is proposed and effectively applied to the kinetics of the hydrogen exchange. The data are described by a power-like function which is based on a time-dependence of the exchange rate. Experimental data ranging over many time scales is considered and accurate fits of a power-like function are obtained. Results of fittings show correlation between faster hydrogen-deuterium exchange and increase of pH. Furthermore a model is presented that discriminates between easily exchangeable hydrogens (located in close proximity to the protein surface) and those protected from the exchange (located in the protein interior). A possible interpretation of the model and its biological significance are discussed.

  14. Kinetic isotope effects for fast deuterium and proton exchange rates

    PubMed Central

    Mammoli, Daniele; Kadeřávek, Pavel; Pelupessy, Philippe; Bodenhausen, Geoffrey

    2016-01-01

    By monitoring the effect of deuterium decoupling on the decay of transverse 15N magnetization in D–15N spin pairs during multiple-refocusing echo sequences, we have determined fast D–D exchange rates k D and compared them with fast H–H exchange rates k H in tryptophan to determine the kinetic isotope effect as a function of pH and temperature. PMID:27009684

  15. Kinetic isotope effects for fast deuterium and proton exchange rates.

    PubMed

    Canet, Estel; Mammoli, Daniele; Kadeřávek, Pavel; Pelupessy, Philippe; Bodenhausen, Geoffrey

    2016-04-21

    By monitoring the effect of deuterium decoupling on the decay of transverse (15)N magnetization in D-(15)N spin pairs during multiple-refocusing echo sequences, we have determined fast D-D exchange rates kD and compared them with fast H-H exchange rates kH in tryptophan to determine the kinetic isotope effect as a function of pH and temperature.

  16. Ion exchange materials, method of forming ion exchange materials, and methods of treating liquids

    DOEpatents

    Wertsching, Alan K.; Peterson, Eric S.; Wey, John E.

    2007-12-25

    The invention includes an ion affinity material having an organic component which is sulfonated and which is chemically bonded to an inorganic substrate component. The invention includes a method of forming a metal binding material. A solid support material comprising surface oxide groups is provided and an organic component having at least one alkyl halide is covalently linked to at least some of the surface oxide groups to form a modified support material. The at least one alkyl halide is subsequently converted into an alkyl sulfonate. The invention further includes a method and system for extracting ions from a liquid. An ion exchange material having a sulfonated alkyl silane component covalently bonded to a metal oxide support material is provided and a liquid is exposed to the ion exchange material.

  17. Ion kinetic transport in TJ-II

    SciTech Connect

    Velasco, J. L.; Tarancon, A.; Castejon, F.; Fernandez, L. A.; Martin-Mayor, V.

    2008-11-02

    The ion Drift Kinetic Equation (DKE) which describes the ion collisional transport is solved for the TJ-II device plasmas. This non-linear equation is computed by performing a mean field iterative calculation. In each step of the calculation, a Fokker-Planck equation is solved by means of the Langevin approach: one million particles are followed in a realistic TJ-II magnetic configuration, taking into account collisions and electric field. This allows to avoid the assumptions made in the usual neoclassical approach, namely considering radially narrow particle trajectories, diffusive transport, energy conservation and infinite parallel transport. As a consequence, global features of transport, not present in the customary neoclassical models, appear: non-diffusive transport and asymmetries on the magnetic surfaces.

  18. Solidification of ion exchange resin wastes

    SciTech Connect

    Not Available

    1982-08-01

    Solidification media investigated included portland type I, portland type III and high alumina cements, a proprietary gypsum-based polymer modified cement, and a vinyl ester-styrene thermosetting plastic. Samples formulated with hydraulic cement were analyzed to investigate the effects of resin type, resin loading, waste-to-cement ratio, and water-to-cement ratio. The solidification of cation resin wastes with portland cement was characterized by excessive swelling and cracking of waste forms, both after curing and during immersion testing. Mixed bed resin waste formulations were limited by their cation component. Additives to improve the mechanical properties of portland cement-ion exchange resin waste forms were evaluated. High alumina cement formulations dislayed a resistance to deterioration of mechanical integrity during immersion testing, thus providing a significant advantage over portland cements for the solidification of resin wastes. Properties of cement-ion exchange resin waste forms were examined. An experiment was conducted to study the leachability of /sup 137/Cs, /sup 85/Sr, and /sup 60/Co from resins modified in portland type III and high alumina cements. The cumulative /sup 137/Cs fraction release was at least an order of magnitude greater than that of either /sup 85/Sr or /sup 60/Co. Release rates of /sup 137/Cs in high alumina cement were greater than those in portland III cement by a factor of two.Compressive strength and leach testing were conducted for resin wastes solidified with polymer-modified gypsum based cement. /sup 137/Cs, /sup 85/Sr, and /sup 60/Co fraction releases were about one, two and three orders of magnitude higher, respectively, than in equivalent portland type III cement formulations. As much as 28.6 wt % dry ion exchange resin was successfully solidified using vinyl ester-styrene compared with a maximum of 25 wt % in both portland and gypsum-based cement.

  19. Biodegradation of ion-exchange media

    SciTech Connect

    Bowerman, B.S.; Clinton, J.H.; Cowdery, S.R.

    1988-01-01

    The purpose of this study was to investigate further the potential for ion-exchange media (resin beads or powdered filter media) to support biological growth. A mixed microbial culture was grown from resin wastes obtained from the BNL HFBR by mixing the resin with a nutrient salt solution containing peptone and yeast extract. Bacterial and fungal growths appeared in the solution and on the resins after 7 to 10 days incubation at 337)degree)C. The mixed microbial cultures were used to inoculate several resin types, both irradiated and unirradiated. 12 refs., 5 tabs.

  20. Ion exchange polymers and method for making

    NASA Technical Reports Server (NTRS)

    Philipp, Warren H. (Inventor); Street, Kenneth W., Jr. (Inventor)

    1994-01-01

    An ion exchange polymer comprised of an alkali metal or alkaline earth metal salt of a poly(carboxylic acid) in a poly(vinyl acetal) matrix is described. The polymer is made by treating a mixture made of poly(vinyl alcohol) and poly(acrylic acid) with a suitable aldehyde and an acid catalyst to cause acetalization with some cross-linking. The material is then subjected to an alkaline aqueous solution of an alkali metal salt or an alkali earth metal salt. All of the film forming and cross-linking steps can be carried out simultaneously, if desired.

  1. Trivalent Ion Exchange in Beta’ Alumina.

    DTIC Science & Technology

    1984-07-06

    halide salt. required higher aticmp I We hew fotat t bet ain synthesis tempratures then wm usned for the are apale f mqporingtrivlen caion divalent...s a dni Table I . Trivalent, Zen Exchngeondiion ion Halt Coqoition ToW (OC) time(h) lexcdwmge Gd3 Gda1 615 5 100 Nd3+ dr 2 . 95 i1d3 45 MM /AS umcl...properties The fluorescence spectra of kUd’* exchanged Ita mtdctivity for Gd3 + beta" aluina Wben" alumina are ganerally similar to that of was masurd

  2. Fixation of radioactive ions in porous media with ion exchange gels

    DOEpatents

    Mercer, Jr., Basil W.; Godfrey, Wesley L.

    1979-01-01

    A method is provided for fixing radioactive ions in porous media by injecting into the porous media water-soluble organic monomers which are polymerizable to gel structures with ion exchange sites and polymerizing the monomers to form ion exchange gels. The ions and the particles of the porous media are thereby physically fixed in place by the gel structure and, in addition, the ions are chemically fixed by the ion exchange properties of the resulting gel.

  3. Proton/calcium ion exchange behavior of calcite.

    PubMed

    Villegas-Jiménez, Adrián; Mucci, Alfonso; Paquette, Jeanne

    2009-10-21

    The characterization of the proton sorptive properties of calcite in aqueous solutions at 25 +/- 1 degrees C over a relatively wide range of chemical conditions (7.16 ions is consistently observed, greatly exceeding the theoretical number of reactive surface sites. These observations are interpreted as a fast proton/calcium exchange equilibrium between the solution and "exchangeable cation sites" (e.g., lattice positions) at and/or beneath the calcite surface (species identified by "(exc)"), , that leads to a transient, "apparent" incongruent dissolution regime and the formation of a stable calcium-deficient, proton-enriched layer within the calcite lattice under circum-neutral and alkaline regimes at standard conditions. The 2H(+)/Ca(2+) ion exchange is quantitatively described by the Langmuir-power exchange function under the Vanselow convention: where n = 1 and log(10)K(ex) = 13.0 +/- 0.3. This calcite behavior, never reported before, masks surface equilibria and directly impacts the aqueous speciation of carbonate-rock systems with poor CO(2)(g) ventilation (e.g., aquifers, pore and deep sea waters, industrial reactors) via the buffering of pH and calcite dissolution. In contrast, at fixed pCO(2) conditions, aqueous speciation remains unaffected upon CO(2)(g) sequestration resulting from ion exchange-induced calcite precipitation: ([triple bond]CaCO3)2(exc) + CO2(g) + H2O <==> [triple bond]Ca(HCO3)2(exc) + CaCO3(s). Accordingly, reliable predictions of aqueous speciation in natural or engineered calcite-containing systems at variable pCO(2) conditions must consider this exchange reaction and the associated K(ex). The postulated proton/calcium exchange may have far

  4. Adsorption and ion exchange: basic principles and their application in food processing.

    PubMed

    Kammerer, Judith; Carle, Reinhold; Kammerer, Dietmar R

    2011-01-12

    A comprehensive overview of adsorption and ion exchange technology applied for food and nutraceutical production purposes is given in the present paper. Emanating from these fields of application, the main adsorbent and ion-exchange resin materials, their historical development, industrial production, and the main parameters characterizing these sorbents are covered. Furthermore, adsorption and ion exchange processes are detailed, also providing profound insights into kinetics, thermodynamics, and equilibrium model assumptions. In addition, the most important industrial adsorber and ion exchange processes making use of vessels and columns are summarized. Finally, an extensive overview of selected industrial applications of these technologies is provided, which is divided into general applications, food production applications, and the recovery of valuable bio- and technofunctional compounds from the byproducts of plant food processing, which may be used as natural food additives or for their potential health-beneficial effects in functional or enriched foods and nutraceuticals.

  5. Anisotropic microporous supports impregnated with polymeric ion-exchange materials

    DOEpatents

    Friesen, Dwayne; Babcock, Walter C.; Tuttle, Mark

    1985-05-07

    Novel ion-exchange media are disclosed, the media comprising polymeric anisotropic microporous supports containing polymeric ion-exchange or ion-complexing materials. The supports are anisotropic, having small exterior pores and larger interior pores, and are preferably in the form of beads, fibers and sheets.

  6. Anisotropic microporous supports impregnated with polymeric ion-exchange materials

    DOEpatents

    Friesen, D.; Babcock, W.C.; Tuttle, M.

    1985-05-07

    Novel ion-exchange media are disclosed, the media comprising polymeric anisotropic microporous supports containing polymeric ion-exchange or ion-complexing materials. The supports are anisotropic, having small exterior pores and larger interior pores, and are preferably in the form of beads, fibers and sheets. 5 figs.

  7. Ion Exchange Chromatography and Spectrophotometry: An Introductory Undergraduate Laboratory Experiment.

    ERIC Educational Resources Information Center

    Foster, N.; And Others

    1985-01-01

    Describes an experiment in which students use ion exchange chromatography to separate a mixture of chloro complexes of transition metal ions and then use spectrophotometry to define qualitatively the efficiency of the ion exchange columns. Background information, materials needed, and procedures used are included. (JN)

  8. Ion Exchange Chromatography and Spectrophotometry: An Introductory Undergraduate Laboratory Experiment.

    ERIC Educational Resources Information Center

    Foster, N.; And Others

    1985-01-01

    Describes an experiment in which students use ion exchange chromatography to separate a mixture of chloro complexes of transition metal ions and then use spectrophotometry to define qualitatively the efficiency of the ion exchange columns. Background information, materials needed, and procedures used are included. (JN)

  9. Effects of apolipoproteins on the kinetics of cholesterol exchange

    SciTech Connect

    Letizia, J.Y.; Phillips, M.C. )

    1991-01-22

    The effects of apolipoproteins on the kinetics of cholesterol exchange have been investigated by monitoring the transfer of ({sup 14}C)cholesterol from donor phospholipid/cholesterol complexes containing human apolipoproteins A, B, or C. Negatively charged discoidal and vesicular particles containing purified apolipoproteins complexed with lipid and a trace of ({sup 14}C)cholesterol were incubated with a 10-fold excess of neutral, acceptor, small unilamellar vesicles. The donor and acceptor particles were separated by chromatogrphy of DEAE-Sepharose, and the rate of movement of labeled cholesterol was analyzed as a first-order exchange process. The kinetics of exchange of cholesterol from both vesicular and discoidal complexes that contain apoproteins are consistent with an aqueous diffusion mechanism, as has been established previously for PC/cholesterol SUV. Apolipoproteins A-I, A-II, reduced and carboxymethylated A-11, and B-100 present in SUV at the same lipid/protein (w/w) ratio all enhance the rate of cholesterol exchange to about the same degree. Cholesterol molecules exchange more rapidly from discoidal complexes. Generally, as the diameter of apoprotein/phospholipid/cholesterol discs decreases, t{sub 1/2} for cholesterol exchange decreases. Since small bilayer discs have a relatively high ratio of boundary to face surface area, cholesterol molecules desorb more rapidly than from larger discs. The modulation of lipid packing by the apoprotein molecules present at the surface of lipoprotein particles affects the rate of cholesterol exchange from such particles.

  10. Kinetic exchange models: From molecular physics to social science

    NASA Astrophysics Data System (ADS)

    Patriarca, Marco; Chakraborti, Anirban

    2013-08-01

    We discuss several multi-agent models that have their origin in the kinetic exchange theory of statistical mechanics and have been recently applied to a variety of problems in the social sciences. This class of models can be easily adapted for simulations in areas other than physics, such as the modeling of income and wealth distributions in economics and opinion dynamics in sociology.

  11. Kinetic models for wealth exchange on directed networks

    NASA Astrophysics Data System (ADS)

    Chatterjee, A.

    2009-02-01

    We propose some kinetic models of wealth exchange and investigate their behavior on directed networks though numerical simulations. We observe that network topology and directedness yields a variety of interesting features in these models. The nature of asset distribution in such directed networks show varied results, the degree of asset inequality increased with the degree of disorder in the graphs.

  12. Radionuclide Leaching from Organic Ion Exchange Resin

    SciTech Connect

    Delegard, C.H.; Rinehart, D.E.

    1999-04-02

    Laboratory tests were performed to examine the efficacy of leach treatments for decontaminating organic ion exchange resins (OIER), which have been found in a number of samples retrieved from K East Basin sludge. Based on process records, the OIER found in the K Basins is a mixed-bet strong acid/strong base material marketed as Purolite{trademark} NRW-037. Radionuclides sorbed or associated with the OIER can restrict its disposal to the Environmental Restoration Disposal Facility (ERDF). The need for testing to support development of a treatment process for K Basin sludge has been described in Section 4.2 of ''Testing Strategy to Support the Development of K Basins Sludge Treatment Process'' (Flament 1998). To help understand the effects of anticipated OIER elutriation and washing, tests were performed with well-rinsed OIER material from K East Basin floor sludge (sample H-08 BEAD G) and with well-rinsed OIER having approximately 5% added K East canister composite sludge (sample KECOMP). The rinsed resin-bearing material also contained the inorganic ion exchanger Zeolon-900{trademark}, a zeolite primarily composed of the mineral mordenite. The zeolite was estimated to comprise 27 weight percent of the dry H-08 BEAD G material.

  13. Multicomponent liquid ion exchange with chabazite zeolites

    SciTech Connect

    Robinson, S.M.; Arnold, W.D. Jr.; Byers, C.W.

    1993-10-01

    In spite of the increasing commercial use of zeolites for binary and multicomponent sorption, the understanding of the basic mass-transfer processes associated with multicomponent zeolite ion-exchange systems is quite limited. This study was undertaken to evaluate Na-Ca-Mg-Cs-Sr ion exchange from an aqueous solution using a chabazite zeolite. Mass-transfer coefficients and equilibrium equations were determined from experimental batch-reactor data for single and multicomponent systems. The Langmuir isotherm was used to represent the equilibrium relationship for binary systems, and a modified Dubinin-Polyani model was used for the multicomponent systems. The experimental data indicate that diffusion through the microporous zeolite crystals is the primary diffusional resistance. Macropore diffusion also significantly contributes to the mass-transfer resistance. Various mass-transfer models were compared to the experimental data to determine mass-transfer coefficients. Effective diffusivities were obtained which accurately predicted experimental data using a variety of models. Only the model which accounts for micropore and macropore diffusion occurring in series accurately predicted multicomponent data using single-component diffusivities. Liquid and surface diffusion both contribute to macropore diffusion. Surface and micropore diffusivities were determined to be concentration dependent.

  14. Brown coals as natural electron-ion-exchangers

    SciTech Connect

    Kossov, I.I.; Aleksandrov, I.V.; Kamneva, A.I.

    1984-01-01

    The existence of electron-ion-exchange properties in brown coals has been established. The influence of the redox properties of the organic and mineral fractions of the coals on their capacity for electron exchange has been shown.

  15. Seleniranium Ions Undergo π-Ligand Exchange via an Associative Mechanism in the Gas Phase.

    PubMed

    Lim, S Fern; Harris, Benjamin L; Khairallah, George N; Bieske, E J; Maître, Philippe; da Silva, Gabriel; Adamson, Brian D; Scholz, Michael S; Coughlan, Neville J A; O'Hair, Richard A J; Rathjen, Michael; Stares, Daniel; White, Jonathan M

    2017-06-16

    Collision-induced dissociation mass spectrometry of the ammonium ions 4a and 4b results in the formation of the seleniranium ion 5, the structure and purity of which were verified using gas-phase infrared spectroscopy coupled to mass spectrometry and gas-phase ion-mobility measurements. Ion-molecule reactions between the ion 5 (m/z = 261) and cyclopentene, cyclohexene, cycloheptene, and cyclooctene resulted in the formation of the seleniranium ions 7 (m/z = 225), 6 (m/z = 239), 8 (m/z = 253), and 9 (m/z = 267), respectively. Further reaction of seleniranium 6 with cyclopentene resulted in further π-ligand exchange giving seleniranium ion 7, confirming that direct π-ligand exchange between seleniranium ion 5 and cycloalkenes occurs in the gas phase. Pseudo-first-order kinetics established relative reaction efficiencies for π-ligand exchange for cyclopentene, cyclohexene, cycloheptene. and cyclooctene as 0.20, 0.07, 0.43, and 4.32. respectively. DFT calculations at the M06/6-31+G(d) level of theory provide the following insights into the mechanism of the π-ligand exchange reactions; the cycloalkene forms a complex with the seleniranium ion 5 with binding energies of 57 and 62 kJ/mol for cyclopentene and cyclohexene, respectively, with transition states for π-ligand exchange having barriers of 17.8 and 19.3 kJ/mol for cyclopentene and cyclohexene, respectively.

  16. Ion exchange of cesium by crystalline silico-titanates

    SciTech Connect

    Zheng, Zhixin; Anthony, R.G.; Miller, J.E.; Trudell, D.

    1995-12-01

    The crystalline silico-titanates developed by the Department of Chemical Engineering at Texas A&M University, Sandia National Laboratories and UOP exhibits extremely high ion exchange selectivity for removing cesium from aqueous defense wastes. Based on experimental data and structure studies, a competitive ion exchange model was proposed to predict the ion exchange performance in different simulated waste solutions. The predicted distribution coefficients were within 10% of the experimentally determined values.

  17. Mineral Separation in a CELSS by Ion-exchange Chromatography

    NASA Technical Reports Server (NTRS)

    Ballou, E. V.; Spitze, L. A.; Wong, F. W.; Wydeven, T.; Johnson, C. C.

    1982-01-01

    Operational parameters pertinent to ion exchange chromatography separation were identified. The experiments were performed with 9 mm diameter ion exchange columns and conventional column accessories. The cation separation beds were packed with AG 50W-X2 strong acid cation exchange resin in H(+) form and 200-400 dry mesh particle size. The stripper beds used in some experiments were packed with AG 1-XB strong base cation exchange resin in OH(-) form and 200-400 dry mesh particle size.

  18. Ion Exchange Testing with SRF Resin FY2012

    SciTech Connect

    Russell, Renee L.; Rinehart, Donald E.; Peterson, Reid A.

    2013-06-11

    Ion exchange using spherical resorcinol-formaldehyde (SRF) resin has been selected by the U.S. Department of Energy’s Office of River Protection (DOE-ORP) for use in the Pretreatment Facility (PTF) of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) and for potential application in at-tank deployment. Numerous studies have shown SRF resin to be effective for removing 137Cs from a wide variety of actual and simulated tank waste supernatants (Adamson et al. 2006; Blanchard et al. 2008; Burgeson et al. 2004; Duignan and Nash 2009; Fiskum et al. 2006a; Fiskum et al. 2006b; Fiskum et al. 2006c; Fiskum et al. 2007; Hassan and Adu-Wusu 2003; King et al. 2004; Nash et al. 2006). Prior work at the Pacific Northwest National Laboratory (PNNL) has focused primarily on the loading behavior for 4 to 6 M Na solutions at 25 to 45°C. Recent proposed changes to the WTP ion exchange process baseline indicate that loading may include a broader range of sodium molarities (0.1 to 8 M) and higher temperatures (50°C) to alleviate post-filtration precipitation issues. This report discusses ion exchange loading kinetics testing activities performed in accordance with Test Plan TP-WTPSP-002, Rev. 3.0 , which was prepared and approved in response to the Test Specification 24590 PTF-TSP-RT-09-002, Rev. 0 (Lehrman 2010) and Test Exception 24590 PTF TEF RT-11-00003, Rev. 0 (Meehan 2011). This testing focused on column tests evaluating the impact of elevated temperature on resin degradation over an extended period of time and batch contacts evaluating the impact on Cs loading over a broad range of sodium concentrations (0.1 to 5 M). These changes may be required to alleviate post-filtration precipitation issues and broaden the data range of SRF resin loading under the conditions expected with the new equipment and process changes.

  19. Zeolitic ammonium ion exchange for portable hemodialysis dialysate regeneration.

    PubMed

    Patzer, J F; Yao, S J; Wolfson, S K

    1995-01-01

    Ammonia removal from a recirculating dialysate stream is a major challenge in developing a truly portable, regenerable hemodialysis system. Three zeolites, type F, type W, and clinoptilolite, were found to have good ammonia ion exchange capacity with linear equilibrium ion exchange coefficients of 0.908, 0.488, and 0.075 L/g, respectively. The linear equilibrium ion exchange coefficient relates dialysate ammonia concentration (mumol/L) to the amount of ammonia absorbed by zeolite (mumol/g) at equilibrium. Ammonia uptake by zeolite powders was fast, with equilibrium reached within 15 sec. Zeolite ammonia ion exchange and regeneration through multiple cycles was studied using an ion exchange column containing clinoptilolite pellets. Zeolite ion exchange capability was regenerated by flushing the column with 2 mol/L sodium chloride after an ion exchange run. The column maintained ammonia ion exchange capacity through six ion exchange/regeneration cycles, demonstrating multiple dialysis use possibilities. Atomic absorption spectroscopy of the column effluent showed no detectible (< 1 part per million) Si or Al leached from the zeolite.

  20. Complexation ion-exchange chromatography of some metal ions on papers impregnated with Ti(IV)-based inorganic ion exchangers.

    PubMed

    Sharma, S D; Gupta, R

    2000-02-01

    The chromatographic behavior of 40 metal ions is studied on titanium (IV) arsenate, titanium (IV) phosphate-, titanium (IV) molybdate-, titanium(IV) tungstate-, and titanium(IV) selenite-impregnated papers in 0.1M oxalic, citric, and tartaric acid as mobile phases. Similar studies are carried out on Whatman No. 1 papers for comparison. The ion-exchange capacity of these papers is determined, and their selectivity for different cations is discussed. The mechanism of migration is explained in terms of ion-exchange, precipitation, and adsorption. The prediction of elution sequence from RF values is also checked. The average Ri is found to be almost linearly dependent on the charge of the metal ions. The effect of the pKa of complexing acids on average RF values of 3d series metal ions is explained. A number of binary and ternary separations are achieved.

  1. Effects of ionizing radiation on modern ion exchange materials

    SciTech Connect

    Marsh, S.F.; Pillay, K.K.S.

    1993-10-01

    We review published studies of the effects of ionizing radiation on ion exchange materials, emphasizing those published in recent years. A brief overview is followed by a more detailed examination of recent developments. Our review includes styrene/divinylbenzene copolymers with cation-exchange or anion-exchange functional groups, polyvinylpyridine anion exchangers, chelating resins, multifunctional resins, and inorganic exchangers. In general, strong-acid cation exchange resins are more resistant to radiation than are strong-base anion exchange resins, and polyvinylpyridine resins are more resistant than polystyrene resins. Cross-linkage, salt form, moisture content, and the surrounding medium all affect the radiation stability of a specific exchanger. Inorganic exchangers usually, but not always, exhibit high radiation resistance. Liquid ion exchangers, which have been used so extensively in nuclear processing applications, also are included.

  2. Kinetic theory of oxygen isotopic exchange between minerals and water

    USGS Publications Warehouse

    Criss, R.E.; Gregory, R.T.; Taylor, H.P.

    1987-01-01

    Kinetic and mass conservation equations are used to describe oxygen isotopic exchange between minerals and water in "closed" and open hydrothermal systems. In cases where n coexisting mineral phases having different reaction rates are present, the exchange process is described by a system of n + 1 simultaneous differential equations consisting of n pseudo first-order rate equations and a conservation of mass equation. The simultaneous solutions to these equations generate curved exchange trajectories on ??-?? plots. Families of such trajectories generated under conditions allowing for different fluid mole fractions, different fluid isotopic compositions, or different fluid flow rates are connected by positive-sloped isochronous lines. These isochrons reproduce the effects observed in hydrothermally exchanged mineral pairs including 1) steep positive slopes, 2) common reversals in the measured fractionation factors (??), and 3) measured fractionations that are highly variable over short distances where no thermal gradient can be geologically demonstrated. ?? 1987.

  3. Scintillating 99Tc Selective Ion Exchange Resins

    SciTech Connect

    Mitchell Greenhalgh; Richard D. Tillotson

    2012-07-01

    Scintillating technetium (99Tc) selective ion exchange resins have been developed and evaluated for equilibrium capacities and detection efficiencies. These resins can be utilized for the in-situ concentration and detection of low levels of pertechnetate anions (99TcO4-) in natural waters. Three different polystyrene type resin support materials were impregnated with varying amounts of tricaprylmethylammonium chloride (Aliquat 336) extractant, several different scintillating fluors and wavelength shifters. The prepared resins were contacted batch-wise to equilibrium over a wide range of 99TcO4- concentrations in natural water. The measured capacities were used to develop Langmuir adsorption isotherms for each resin. 99Tc detection efficiencies were determined and up to 71.4 ± 2.6% was achieved with some resins. The results demonstrate that a low level detection limit for 99TcO4- in natural waters can be realized.

  4. Pyrolysis of Spent Ion Exchange Resins - 12210

    SciTech Connect

    Braehler, Georg; Slametschka, Rainer

    2012-07-01

    Organic ion exchangers (IEX) play a major and increasing role in the reactor coolant and other water purification processes. During their operation time they receive significant amounts of radioactivity, making their disposal, together with their organic nature, as medium active waste challenging. Processes applied so far do not eliminate the organic matter, which is unwanted in disposal facilities, or, if high temperatures are applied, raise problems with volatile radionuclides. NUKEM Technologies offers their well introduces process for the destruction of spent solvent (TBP), the pebble bed pyrolysis, now for the treatment of spent IEX (and other problematic waste), with the following benefits: the pyrolysis product is free of organic matter, and the operation temperature with approx. 500 deg. C keeps Cs radionuclides completely in the solid residue. (authors)

  5. TECHNICAL COMPARISON OF CANDIDATE ION EXCHANGE MEDIA FOR SMALL COLUMN ION EXCHANGE (SCIX) APPLICATIONS IN SUPPORT OF SUPPLEMENTAL LAW PRETREATMENT

    SciTech Connect

    RAMSEY AA; THORSON MR

    2010-12-28

    At-tank supplemental pretreatment including both filtration and small column ion exchange is currently under evaluation to facilitate salt waste retrieval and processing in the Hanford tank farms. Spherical resorcinol formaldehyde (sRF) resin is the baseline ion exchange resin for use in the Waste Treatment and Immobilization Plant (WTP). This document provides background and technical rationale to assist in determining whether spherical resorcinol formaldehyde (sRF) is also the appropriate ion exchange resin for supplemental LAW pretreatment processes and compares sRF with crystalline silicotitanate (CST) as potential supplemental pretreatment ion exchange media.

  6. Waste treatment by selective mineral ion exchanger

    SciTech Connect

    Polito, Aurelie

    2007-07-01

    STMI, subsidiary company of the AREVA Group with over 40 years in the D and D business, has been continuously innovating and developing new decontamination techniques, with the objectives of achieving more efficient decontaminations on a growing spectrum of media. In the field of liquid waste treatment, STMI manufactures uses and commercialises selective inorganic ion exchangers (RAN). These are hydrated synthetic inorganic compounds prepared from very pure raw materials. Different types of RANs (POLYAN, OXTAIN, Fe-Cu, Fe-CoK, Si-Fe-CoK) can be used to trap a large number of radioactive elements in contaminated effluents. Different implementations could be applied depending on technical conditions. STMI's offers consist in building global solution and preliminary design of installation either in dispersed form (batch) or in column (cartridge filtration). Those products are used all over the world not only in the nuclear business (Canada, US, Belgium, France...) but also in other fields. Indeed, it provides competitive solutions to many domains of application especially water pollution control, liquid waste treatment in the nuclear business by decreasing the activity level of waste. The following paper will focus on the theoretical principle of the mineral exchanger, its implementation and the feed back collected by STMI. (author)

  7. Adsorption of three pharmaceuticals on two magnetic ion-exchange resins.

    PubMed

    Jiang, Miao; Yang, Weiben; Zhang, Ziwei; Yang, Zhen; Wang, Yuping

    2015-05-01

    The presence of pharmaceuticals in aquatic environments poses potential risks to the ecology and human health. This study investigated the removal of three widely detected and abundant pharmaceuticals, namely, ibuprofen (IBU), diclofenac (DC), and sulfadiazine (SDZ), by two magnetic ion-exchange resins. The adsorption kinetics of the three adsorbates onto both resins was relatively fast and followed pseudo-second-order kinetics. Despite the different pore structures of the two resins, similar adsorption patterns of DC and SDZ were observed, implying the existence of an ion-exchange mechanism. IBU demonstrated a combination of interactions during the adsorption process. These interactions were dependent on the specific surface area and functional groups of the resin. The adsorption isotherm fittings verified the differences in the behavior of the three pharmaceuticals on the two magnetic ion-exchange resins. The presence of Cl- and SO4(2-) suppressed the adsorption amount, but with different inhibition levels for different adsorbates. This work facilitates the understanding of the adsorption behavior and mechanism of pharmaceuticals on magnetic ion-exchange resins. The results will expand the application of magnetic ion-exchange resins to the removal of pharmaceuticals in waters.

  8. Radiation testing of organic ion exchange resins

    SciTech Connect

    Carlson, C.D.; Bray, L.A.; Bryan, S.A.

    1995-09-01

    A number of ion exchange materials are being evaluated as part of the Tank Waste Remediation System (TWRS) Pacific Northwest Laboratory (PNL) Pretreatment Project for the removal of {sup 137}Cs from aqueous tank wastes. Two of these materials are organic resins; a phenol-formaldehyde resin (Duolite CS-100) produced by Rohm and Haas Co. (Philadelphia, Pennsylvania) and a resorcinol-formaldehyde (RF) resin produced by Boulder Scientific Co. (Mead, Colorado). One of the key parameters in the assessment of the organic based ion exchange materials is its useful lifetime in the radioactive and chemical environment that will be encountered during waste processing. The focus of the work presented in this report is the radiation stability of the CS-100 and the RF resins. The scope of the testing included one test with a sample of the CS-100 resin and testing of two batches of the RF resin (BSC-187 and BSC-210). Samples of the exchangers were irradiated with a {sup 60}Co source to a total absorbed dose of 10{sup 9} R over a period of 5 months in a static (no flow) and a flowing configuration with neutralized current acid waste (NCAW) simulant as a feed. Based on a maximum concentration of {sup 137}Cs on the resin that would result from processing NCAW, this dose represents an operational period of at least 150 days for the RF resin and at least 1260 days for the CS-100 resin. Gas generation in the static experiment was continuously monitored and G values (molecules of gas per 100 eV) were determined for each species. Resin samples were obtained periodically and the equilibrium behavior of the resins was assessed by determining the distribution coefficients (K{sub d}s). Structural information was also obtained by {sup 13}C cross polarization magic angle (CPMAS) nuclear magnetic resonance (NMR) spectrometry and Fourier Transform Infrared (FTIR) spectroscopy so that changes to the chemical structure could be correlated with changes in K{sub d}.

  9. ION EXCHANGE IN FUSED SALTS. II. THE DISTRIBUTION OF ALKALI METAL AND ALKALINE EARTH IONS BETWEEN CHABAZITE AND FUSED LINO3, NANO3, AND KNO3,

    DTIC Science & Technology

    ION EXCHANGE, SALTS ), (*ALKALI METALS, ION EXCHANGE), (*ALKALINE EARTH METALS, ION EXCHANGE), (*NITRATES, ION EXCHANGE), SODIUM , CALCIUM, POTASSIUM...BARIUM, RUBIDIUM, CESIUM, LITHIUM COMPOUNDS, SODIUM COMPOUNDS, POTASSIUM COMPOUNDS, DISTRIBUTION, MINERALS, IONS

  10. Rupture Loop Annex (RLA) ion exchange vault entry and characterization

    SciTech Connect

    Ham, J.E.

    1996-01-04

    This engineering report documents the entry and characterization of the Rupture Loop Annex Ion Exchange (RLAIX) Vault located near the 309 Building`s Plutonium Recycle Test Reactor (PRTR). Twelve ion exchange columns were found in the vault. Some of which contained transuranics, Cs 137, and Co 60. The characterization information is necessary for future vault cleanout and column disposal.

  11. Kinetics of interlayer ion migration in non-swelling clays: An atomic-scale study

    NASA Astrophysics Data System (ADS)

    Lammers, L. N.; Kolluri, K.

    2015-12-01

    Clay-rich geologic repositories serve as hosts for fossil methane reserves and as traps for contaminant radionuclides and sequestered CO2. Despite the abundance of non-swelling clay minerals in sedimentary formations, the mechanisms of ion exchange and mass transport mediated by these minerals are not well understood. Ion exchange kinetics in collapsed clays are characterized by a long tail of slow exchange, which suggests that interlayer ions can exchange with the bulk solution. Recent High-Resolution TEM evidence suggests that Cs+ ion exchange K+ in collapsed interlayers leads to interstratified structures, where entire interlayers are completely exchanged while others remain pristine [Okamura T et al., (2005) Microscopy 6365-72]. This phenomenon could be explained by kinetic feedbacks arising when a larger ion substitutes for a smaller one, although the details of this exchange mechanism are currently unknown. We investigated the kinetics and mechanisms of interlayer cation migration in illite (K0.7Al2[Al0.7Si3.3O10](OH)2) using molecular simulations. A Monte Carlo scheme was used to distribute interlayer K ions, and these ions were found to prefer sites neighboring two or more Al3+ substitutions in the tetrahedral sheets. Interlayer K+ ion migration between stable ditrigonal cavity sites was observed directly in molecular dynamics simulations performed at temperatures ranging from 500 K to 900 K and at constant volume. The Climbing Image Nudged Elastic Band method was used to determine the activation energy barrier on 660 K+ ion migration paths. Interlayer ions were observed to migrate between stable lattice sites with migration barriers of 2.35 ± 1.06 eV. Only about 20% of this variation is statistically explained by the distribution of charge deficit sites in the layer caused by Al3+ substitution for Si4+. Remarkably, we find that migration barriers decrease as we increase interlayer spacing. These results suggest that frayed edge sites - local regions with

  12. Bifunctional anion-exchange resins with improved selectivity and exchange kinetics

    DOEpatents

    Alexandratos, Spiro D.; Brown, Gilbert M.; Bonnesen, Peter V.; Moyer, Bruce A.

    2000-01-01

    Disclosed herein are a class of anion exchange resins containing two different exchange sites with improved selectivity and sorptive capability for chemical species in solution, such as heptavalent technetium (as pertechnetate anion, TcO.sub.4.sup.-). The resins are prepared by first reacting haloalkylated crosslinked copolymer beads with a large tertiary amine in a solvent in which the resin beads can swell, followed by reaction with a second, smaller, tertiary amine to more fully complete the functionalization of the resin. The resins have enhanced selectivity, capacity, and exchange kinetics.

  13. Bifunctional anion-exchange resins with improved selectivity and exchange kinetics

    SciTech Connect

    Alexandratos, S.D.; Brown, G.M.; Bonnesen, P.V.; Moyer, B.A.

    2000-05-09

    Disclosed herein are a class of anion exchange resins containing two different exchange sites with improved selectivity and sorptive capability for chemical species in solution, such as heptavalent technetium as pertechnetate anion, TcO{sub 4}{sup {minus}}. The resins are prepared by first reacting haloalkylated crosslinked copolymer beads with a large tertiary amine in a solvent in which the resin beads can swell, followed by reaction with a second, smaller, tertiary amine to more fully complete the functionalization of the resin. The resins have enhanced selectivity, capacity, and exchange kinetics.

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

    PubMed

    Widengren, Jerker

    2013-01-01

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

  15. A kinetic folding intermediate probed by native state hydrogen exchange.

    PubMed

    Parker, M J; Marqusee, S

    2001-01-19

    Stopped-flow fluorescence studies on the N-terminal domain of rat CD2 (CD2.d1) have demonstrated that folding from the fully denatured state (U) proceeds via the transient accumulation of an apparent intermediate (I) in a so-called burst phase that precedes the rate-limiting transition leading to the native state (N). A previous pH-dependent equilibrium hydrogen exchange (HX) study identified a subset of amides in CD2.d1 which, under EX2 conditions, exchange from N with free energies greater than or equal to the free energy difference between the N and I states calculated from the stopped-flow data. Under EX1 conditions the rates of HX for these amides tend towards an asymptote that matches the global unfolding rate calculated from the stopped-flow data, suggesting that exchange for these amides requires traversing the N-to-I transition state barrier. Exchange for these amides presumably occurs from exchange-competent forms comprising the kinetic burst phase therefore. To explore this idea further, native state HX (NHX) data have been collected for CD2.d1 under EX2 conditions using denaturant concentrations which span either side of the denaturant concentration where, according to the stopped-flow data, the apparent U and I states are iso-energetic. The data fit to a two-component, sub-global (sg)/global (g) NHX mechanism, yielding Delta G and m value parameters (where the m value is a measure of hydrocarbon solvation). Regression analysis demonstrates that the (m(sg), Delta G(sg)) and (m(g), Delta G(g)) values calculated for this subset of amides correspond with those describing the kinetic burst phase transition. This result confirms the ability of the NHX technique to explore the structural and energetic properties of kinetic folding intermediates. Copyright 2001 Academic Press.

  16. Multiple metal ion exchange equilibria with humic acid

    NASA Astrophysics Data System (ADS)

    Gamble, Donald S.; Schnitzer, M.; Kerndorff, H.; Langford, C. H.

    1983-07-01

    A theoretical description is presented for multiple metal ion-humic acid cation exchange experiments. A law of mass action formalism and mole fraction relationships have been adapted to the simultaneous ion exchange equilibria of twelve cations with humic acid. The formal description relates the number of degrees of freedom of the system to the number of metal ions, identifies the independent variables, and accounts for cation interactions in the exchange equilibrium. A recalculation of experimental results reveals an Irving-Williams type of series for divalent metal ions. The implications of this for agriculture and add rain problems are discussed.

  17. Ion exchange properties of novel hydrous metal oxide materials

    SciTech Connect

    Gardner, T.J.; McLaughlin, L.I.

    1996-12-31

    Hydrous metal oxide (HMO) materials are inorganic ion exchangers which have many desirable characteristics for catalyst support applications, including high cation exchange capacity, anion exchange capability, high surface area, ease of adjustment of acidity and basicity, bulk or thin film preparation, and similar chemistry for preparation of various transition metal oxides. Cation exchange capacity is engineered into these materials through the uniform incorporation of alkali cations via manipulation of alkoxide chemistry. Specific examples of the effects of Na stoichiometry and the addition of SiO{sub 2} to hydrous titanium oxide (HTO) on ion exchange behavior will be given. Acid titration and cationic metal precursor complex exchange will be used to characterize the ion exchange behavior of these novel materials.

  18. Kinetic model of mass exchange with dynamic Arrhenius transition rates

    NASA Astrophysics Data System (ADS)

    Hristopulos, Dionissios T.; Muradova, Aliki

    2016-02-01

    We study a nonlinear kinetic model of mass exchange between interacting grains. The transition rates follow the Arrhenius equation with an activation energy that depends dynamically on the grain mass. We show that the activation parameter can be absorbed in the initial conditions for the grain masses, and that the total mass is conserved. We obtain numerical solutions of the coupled, nonlinear, ordinary differential equations of mass exchange for the two-grain system, and we compare them with approximate theoretical solutions in specific neighborhoods of the phase space. Using phase plane methods, we determine that the system exhibits regimes of diffusive and growth-decay (reverse diffusion) kinetics. The equilibrium states are determined by the mass equipartition and separation nullcline curves. If the transfer rates are perturbed by white noise, numerical simulations show that the system maintains the diffusive and growth-decay regimes; however, the noise can reverse the sign of equilibrium mass difference. Finally, we present theoretical analysis and numerical simulations of a system with many interacting grains. Diffusive and growth-decay regimes are established as well, but the approach to equilibrium is considerably slower. Potential applications of the mass exchange model involve coarse-graining during sintering and wealth exchange in econophysics.

  19. Local structures of ions at ion-exchange resin/solution interface.

    PubMed

    Harada, Makoto; Okada, Tetsuo

    2005-08-26

    The local structures of Cl- and Br- in anion-exchange resins have been studied by X-ray absorption fine structure (XAFS), and separation selectivity is discussed on the basis of results. When two different anion-exchange resins having trimethylammonium and dimethylammonium groups as anion-exchange groups are employed for ion-exchange experiments, slightly higher Br- selectivity has been obtained with the former. XAFS has indicated that the average hydration numbers for a given anion is not affected by the structure of the ion-exchange group, but that the extent of ion-association between the anion and the ion-exchange groups depends on the type of the ion-exchange group. Shorter interaction distance (and in turn stronger ion-association) has been confirmed for the dimethylammonium-type resin, and is consistent with lower Br- selectivity of this resin.

  20. Kinetic analysis of an anion exchange absorbent for CO2 capture from ambient air.

    PubMed

    Shi, Xiaoyang; Li, Qibin; Wang, Tao; Lackner, Klaus S

    2017-01-01

    This study reports a preparation method of a new moisture swing sorbent for CO2 capture from air. The new sorbent components include ion exchange resin (IER) and polyvinyl chloride (PVC) as a binder. The IER can absorb CO2 when surrounding is dry and release CO2 when surrounding is wet. The manuscript presents the studies of membrane structure, kinetic model of absorption process, performance of desorption process and the diffusivity of water molecules in the CO2 absorbent. It has been proved that the kinetic performance of CO2 absorption/desorption can be improved by using thin binder and hot water treatment. The fast kinetics of P-100-90C absorbent is due to the thin PVC binder, and high diffusion rate of H2O molecules in the sample. The impressive is this new CO2 absorbent has the fastest CO2 absorption rate among all absorbents which have been reported by other up-to-date literatures.

  1. Ion exchange defines the biological activity of titanate nanotubes.

    PubMed

    Rónavári, Andrea; Kovács, Dávid; Vágvölgyi, Csaba; Kónya, Zoltán; Kiricsi, Mónika; Pfeiffer, Ilona

    2016-05-01

    One-dimensional titanate nanotubes (TiONTs) were subjected to systematic ion exchange to determine the impact of these modifications on biological activities. Ion exchanged TiONTs (with Ag, Mg, Bi, Sb, Ca, K, Sr, Fe, and Cu ions) were successfully synthesized and the presence of the substituted ions was verified by energy dispersive X-ray spectroscopy (EDS). A complex screening was carried out to reveal differences in toxicity to human cells, as well as in antibacterial, antifungal, and antiviral activities between the various modified nanotubes. Our results demonstrated that Ag ion exchanged TiONTs exerted potent antibacterial and antifungal effects against all examined microbial species but were ineffective on viruses. Surprisingly, the antibacterial activity of Cu/TiONTs was restricted to Micrococcus luteus. Most ion exchanged TiONTs did not show antimicrobial activity against the tested bacterial and fungal species. Incorporation of various ions into nanotube architectures lead to mild, moderate, or even to a massive loss of human cell viability; therefore, this type of biological effect exerted by TiONTs can be greatly modulated by ion exchange. These findings further emphasize the contribution of ion exchange in determining not only the physical and chemical characteristics but also the bioactivity of TiONT against different types of living cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Gadolinium-hydrogen ion exchange of zirconium phosphate

    NASA Technical Reports Server (NTRS)

    Liu, D. C.; Power, J. L.

    1972-01-01

    The Gd(+3)/H(+) ion exchange on a commercial zirconium phosphate ion exchanger was investigated in chloride, sulfate, and phosphate solutions of Gd(+3) at gadolinium concentrations of 0.001 to 1 millimole per cc and in the pH range of 0 to 3.5. Relatively low Gd(+3) capacities, in the range of 0.01 to 0.1 millimole per g of ion exchanger were found at room temperature. A significant difference in Gd(+3) sorption was observed, depending on whether the ion exchanger was converted from initial conditions of greater or lesser Gd(+3) sorption than the specific final conditions. Correlations were found between decrease in Gd(+3) capacity and loss of exchanger phosphate groups due to hydrolysis during washing and between increase in capacity and treatment with H3PO4. Fitting of the experimental data to ideal ion exchange equilibrium expressions indicated that each Gd(+3) ion is sorbed on only one site of the ion exchanger. The selectivity quotient was determined to be 2.5 + or - 0.4 at room temperature on gadolinium desorption in chloride solutions.

  3. Anion exchangers with negatively charged functionalities in hyperbranched ion-exchange layers for ion chromatography.

    PubMed

    Uzhel, Anna S; Zatirakha, Alexandra V; Smirnov, Konstantin N; Smolenkov, Alexandr D; Shpigun, Oleg A

    2017-01-27

    Novel pellicular poly(styrene-divinylbenzene)-based (PS-DVB) anion exchangers with covalently-bonded hyperbranched functional ion-exchange layers containing negatively charged functionalities are obtained and examined. The hyperbranched coating is created on the surface of aminated PS-DVB substrate by repeating the modification cycles including alkylation with 1,4-butanediol diglycidyl ether (1,4-BDDGE), and amination of the terminal epoxide rings with methylamine (MA) or glycine (Gly). The influence of the position and the number of the layers with glycine, as well as of the total number of the layers of amine in the coating on the chromatographic properties of the obtained stationary phases is investigated. Chromatographic performance of the obtained stationary phases is evaluated using the model mixtures of inorganic and organic anions with hydroxide eluent. It is shown that the best selectivity toward weakly retained organic acids and oxyhalides is possessed by the anion exchanger obtained after 5 modification cycles, with glycine being used in the first one. Such anion exchanger packed in 25-cm long column is capable of separating 22 anions in 58min including 7 standard anions, mono-, di- and trivalent organic acids, oxyhalides, and some other double- and triple-charged anions.

  4. Hydrolyzed Poly(acrylonitrile) Electrospun Ion-Exchange Fibers

    PubMed Central

    Jassal, Manisha; Bhowmick, Sankha; Sengupta, Sukalyan; Patra, Prabir K.; Walker, Douglas I.

    2014-01-01

    Abstract A potential ion-exchange material was developed from poly(acrylonitrile) fibers that were prepared by electrospinning followed by alkaline hydrolysis (to convert the nitrile group to the carboxylate functional group). Characterization studies performed on this material using X-ray photoelectron spectroscopy, scanning electron microscopy, Fourier-Transform infra-red spectroscopy, and ion chromatography confirmed the presence of ion-exchange functional group (carboxylate). Optimum hydrolysis conditions resulted in an ion-exchange capacity of 2.39 meq/g. Ion-exchange fibers were used in a packed-bed column to selectively remove heavy-metal cation from the background of a benign, competing cation at a much higher concentration. The material can be efficiently regenerated and used for multiple cycles of exhaustion and regeneration. PMID:24963270

  5. Process parameters optimization in ion exchange 238Pu aqueous processing

    NASA Astrophysics Data System (ADS)

    Pansoy-Hjelvik, M. E.; Nixon, J.; Laurinat, J.; Brock, J.; Silver, G.; Reimus, M.; Ramsey, K. B.

    2000-07-01

    This paper describes bench-scale efforts (5-7 grams of 238Pu) to optimize the ion exchange process for 234U separation with minimal 238Pu losses to the effluent and wash liquids. The bench-scale experiments also determine the methodology to be used for the full-scale process: 5 kg238Pu annual throughput. Heat transfer calculations used to determine the thermal gradients expected during ion exchange processing are also described. The calculations were performed in collaboration with Westinghouse Savannah River Technology Center (WSRTC) and provide information for the design of the full-scale ion exchange equipment.

  6. Ion-exchanged glass waveguide technology: a review

    NASA Astrophysics Data System (ADS)

    Tervonen, Ari; West, Brian R.; Honkanen, Seppo

    2011-07-01

    We review the history and current status of ion exchanged glass waveguide technology. The background of ion exchange in glass and key developments in the first years of research are briefly described. An overview of fabrication, characterization and modeling of waveguides is given and the most important waveguide devices and their applications are discussed. Ion exchanged waveguide technology has served as an available platform for studies of general waveguide properties, integrated optics structures and devices, as well as applications. It is also a commercial fabrication technology for both passive and active wave-guide components.

  7. Ion exchange properties of Japanese natural zeolites in seawater.

    PubMed

    Wajima, Takaaki

    2013-01-01

    Ion exchange properties of five different Japanese natural zeolites in seawater were examined. Sodium ions could be reduced by all zeolites, although anions, Cl(-) and SO(4)(2-), in seawater showed barely changes. Natural zeolite desalination treatment mainly depends on the ion exchange between Na(+), K(+) and Mg(2+) in seawater and Ca(2+) in natural zeolite. This study found that mordenite is superior to clinoptilolite for use in Na(+) reduction. Mordenite with high cation exchange capacity containing Ca(2+) resulted in the highest Na(+) reduction from seawater.

  8. Ion Exchange Column Tests Supporting Technetium Removal Resin Maturation

    SciTech Connect

    Nash, C.; McCabe, D.; Hamm, L.; Smith, F.; Morse, M.

    2013-12-20

    The primary treatment of the tank waste at the DOE Hanford site will be done in the Waste Treatment and Immobilization Plant, currently under construction. The baseline plan for this facility is to treat the waste, splitting it into High Level Waste (HLW) and Low Activity Waste (LAW). Both waste streams are then separately vitrified as glass and sealed in canisters. The LAW glass will be disposed on site. There are currently no plans to treat the waste to remove technetium, so its disposition path is the LAW glass. Due to the soluble properties of pertechnetate and long half-life of 99Tc, effective management of 99Tc is important. Options are being explored to immobilize the supplemental LAW portion of the tank waste, as well as to examine the volatility of 99Tc during the vitrification process. Removal of 99Tc, followed by off-site disposal has potential to reduce treatment and disposal costs. A conceptual flow sheets for supplemental LAW treatment and disposal that could benefit from technetium removal will specifically examine removing 99Tc from the LAW feed stream to supplemental immobilization. SuperLig® 639 is an elutable ion exchange resin. In the tank waste, 99Tc is predominantly found in the tank supernate as pertechnetate (TcO4-). Perrhenate (ReO4-) has been shown to be a good non-radioactive surrogate for pertechnetate in laboratory testing for this ion exchange resin. This report contains results of experimental ion exchange distribution coefficient and column resin maturation kinetics testing using the resin SuperLig® 639a to selectively remove perrhenate from simulated LAW. This revision includes results from testing to determine effective resin operating temperature range. Loading tests were performed at 45°C, and the computer modeling was updated to include the temperature effects. Equilibrium contact testing indicated that this batch of

  9. Ion Exchange Testing with SRF Resin FY 2012

    SciTech Connect

    Russell, Renee L.; Rinehart, Donald E.; Peterson, Reid A.

    2014-07-02

    Ion exchange using spherical resorcinol-formaldehyde (SRF) resin has been selected by the U.S. Department of Energy’s Office of River Protection (DOE-ORP) for use in the Pretreatment Facility (PTF) of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) and for potential application in at-tank deployment. Numerous studies have shown SRF resin to be effective for removing 137Cs from a wide variety of actual and simulated tank waste supernatants (Adamson et al. 2006; Blanchard et al. 2008; Burgeson et al. 2004; Duignan and Nash 2009; Fiskum et al. 2006a; Fiskum et al. 2006b; Fiskum et al. 2006c; Fiskum et al. 2007; Hassan and Adu-Wusu 2003; King et al. 2004; Nash et al. 2006). Prior work at the Pacific Northwest National Laboratory (PNNL) has focused primarily on the loading behavior for 4 to 6 M Na solutions at 25 to 45°C. Recent proposed changes to the WTP ion exchange process baseline indicate that loading may include a broader range of sodium molarities (0.1 to 8 M) and higher temperatures (50°C) to alleviate post-filtration precipitation issues. This report discusses ion exchange loading kinetics testing activities performed in accordance with Test Plan TP-WTPSP-002, Rev. 3.01, which was prepared and approved in response to the Test Specification 24590-PTF-TSP-RT-09-002, Rev. 0 (Lehrman 2010) and Test Exception 24590-PTF-TEF-RT-11-00003, Rev. 0 (Meehan 2011). This testing focused on column tests evaluating the impact of elevated temperature on resin degradation over an extended period of time and batch contacts evaluating the impact on Cs loading over a broad range of sodium concentrations (0.1 to 5 M). These changes may be required to alleviate post-filtration precipitation issues and broaden the data range of SRF resin loading under the conditions expected with the new equipment and process changes.

  10. Tc-99 Ion Exchange Resin Testing

    SciTech Connect

    Valenta, Michelle M.; Parker, Kent E.; Pierce, Eric M.

    2010-08-01

    Pacific Northwest National Laboratory was contracted by CHPRC to evaluate the release of 99Tc from spent resin used to treat water from well 299-W15-765 and stored for several years. The key questions to be answered are: 1) does 99Tc readily release from the spent ion exchange resin after being in storage for several years; 2) if hot water stripping is used to remove the co-contaminant carbon tetrachloride, will 99Tc that has been sequestered by the resin be released; and 3) can spent resin be encapsulated into a cementitious waste form; if so, how much 99Tc would be released from the weathering of the monolith waste form? The results from the long term stability leach test results confirm that the resin is not releasing a significant amount of the sequestered 99Tc, evident by the less than 0.02% of the total 99Tc loaded being identified in the solution. Furthermore, it is possible that the measured 99Tc concentration is the result of 99Tc contained in the pore spaces of the resin. In addition to these results, analyses conducted to examine the impact of hot water on the release of 99Tc suggest that only a small percentage of the total is being released. This suggest that hot water stripping to remove carbon tetrachloride will not have a significant affect on the resin’s ability to hold-on to sequestered 99Tc. Finally, encapsulation of spent resin in a cementitious material may be a viable disposal option, but additional tests are needed to examine the extent of physical degradation caused by moisture loss and the effect this degradation process can have on the release of 99Tc.

  11. Physiological determinants of pulmonary gas exchange kinetics during exercise.

    PubMed

    Whipp, B J; Ward, S A

    1990-02-01

    We consider how the optimal selection of the profile of imposed work rate, coupled with rigorous, statistically justified analysis of the pattern of the pulmonary gas exchange response, makes it possible to assemble a control model incorporating the proportional role of the muscle, circulation, and gas stores. Gains, time constants, and delays may be assigned to the components of the response and its linearity assessed. These techniques also allow the investigator to examine the features of poorly understood and even unexpected response patterns. Recent interest in the analysis of the non-steady state of exercise-in normal subjects and in patients with gas exchange defects-has led to an improved understanding of the sub-threshold dynamics. At work rates above the lactate threshold, the more complex kinetics are to date poorly described, and hence poorly understood, remaining a fertile area for the application of control-systems techniques to exercise.

  12. Hydrogen/deuterium exchange of myoglobin ions in a linear quadrupole ion trap.

    PubMed

    Mao, Dunmin; Ding, Chuanfan; Douglas, D J

    2002-01-01

    The hydrogen/deuterium (H/D) exchange of gas-phase ions of holo- and apo-myoglobin has been studied by confining the ions in a linear quadrupole ion trap with D(2)O or CD(3)OD at a pressure of several mTorr. Apo-myoglobin ions were formed by collision-induced dissociation of holo-myoglobin ions between the orifice and skimmer of the ion sampling system. The exchange takes place on a time scale of seconds. Earlier cross section measurements have shown that holo-myoglobin ions can have more compact structures than apo-myoglobin. Despite this, both holo-myoglobin and apo-myoglobin in charge states +8 to +14 are found to exchange nearly the same number of hydrogens (ca. 103) in 4 s. It is possible the ions fold or unfold to new conformations on the much longer time scale of the exchange experiment compared with the cross section measurements.

  13. Interpenetrating polymer network ion exchange membranes and method for preparing same

    DOEpatents

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

    1989-01-01

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

  14. Kinetic Modeling of Incremental Ambulatory Peritoneal Dialysis Exchanges.

    PubMed

    Guest, Steven; Leypoldt, John K; Cassin, Michelle; Schreiber, Martin

    2017-01-01

    ♦ BACKGROUND: Incremental peritoneal dialysis (PD), the gradual introduction of dialysate exchanges at less than full-dose therapy, has been infrequently described in clinical reports. One concern with less than full-dose dialysis is whether urea clearance targets are achievable with an incremental regimen. In this report, we used a large database of PD patients, across all membrane transport types, and performed urea kinetic modeling determinations of possible incremental regimens for an individual membrane type. ♦ METHODS: Using a modified 3-pore model of peritoneal transport, various incremental manual continuous ambulatory PD (CAPD) exchanges employing glucose and/or icodextrin were evaluated. Peritoneal urea clearances from those simulations were added to residual kidney urea clearance for patients with various glomerular filtration rates (GFRs), and the total weekly urea clearance was then compared to the total weekly urea Kt/V target of 1.7. All 4 peritoneal membrane types were modeled. For each simulated prescription, net ultrafiltration and carbohydrate absorption were also calculated. ♦ RESULTS: Incremental CAPD regimens of 2 exchanges a day met adequacy targets if the GFR was 6 mL/min/1.73 m(2) in all membrane types. For regimens employing 3 exchanges a day, Kt/V targets were achieved at GFR levels of 4 to 5 mL/min/1.73 m(2) in high transporters to low transporters but higher tonicity 2.5% glucose solutions or icodextrin were required in some regimens. ♦ CONCLUSIONS: This work demonstrates that with incremental CAPD regimens, urea kinetic targets are achievable in most new starts to PD with residual kidney function. Incremental PD may be a less intrusive, better accepted initial treatment regime and a cost-effective way to initiate chronic dialysis in the incident patient. The key role of intrinsic kidney function in incremental regimens is highlighted in this analysis and would warrant conscientious monitoring. Copyright © 2017 International

  15. XAFS Studies of Silver Environments in Ion-Exchanged Glasses

    SciTech Connect

    Yang, X. C.; Dubiel, M.

    2007-02-02

    The X-ray absorption fine structure (XAFS) technique was used to analyze the structural geometry of Ag atoms introduced into soda-lime silicate glass and soda aluminosilicate glass by ion-exchange methods. The results show that Ag+ ions in aluminosilicate glass are coordinated by about two oxygens and the nearest-neighbor Ag-O distance increases when the Ag+-for-Na+ ion-exchange ratio is larger than 0.47. When the exchange ratio is low, the introduced Ag+ ions are stabilized at the non-bridge oxygen (NBO) site with a Ag-O distance of 2.20 A, and the Na+ ions in the AlO4 site are exchanged by Ag+ ions after full replacement of the NBO sites with a Ag-O distance of 2.28 A. The disorder of Ag-O coordination increases with increasing ion-exchange ratio in aluminosilicate glass where Ag+ ions are coordinated by NBO and bridge oxygen (BO)

  16. Ion Exchange Separation of the Oxidation State of Vanadium.

    ERIC Educational Resources Information Center

    Cornelius, Richard

    1980-01-01

    Describes an experiment that emphasizes the discrete nature of the different oxidation states of vanadium by the separation of ammonium metavanadate into all four species by ion exchange chromatography. (CS)

  17. Ion Exchange Separation of the Oxidation State of Vanadium.

    ERIC Educational Resources Information Center

    Cornelius, Richard

    1980-01-01

    Describes an experiment that emphasizes the discrete nature of the different oxidation states of vanadium by the separation of ammonium metavanadate into all four species by ion exchange chromatography. (CS)

  18. Ion exchange of several radionuclides on the hydrous crystalline silicotitanate, UOP IONSIV IE-911

    SciTech Connect

    Huckman, M.E.; Latheef, I.M.; Anthony, R.G.

    1999-04-01

    The crystalline silicotitanate, UOP IONSIV IE-911, is a proven material for removing radionuclides from a wide variety of waste streams. It is superior for removing several radionuclides from the highly alkaline solutions typical of DOE wastes. This laboratory previously developed an equilibrium model applicable to complex solutions for IE-910 (the power form of the granular IE-911), and more recently, the authors have developed several single component ion-exchange kinetic models for predicting column breakthrough curves and batch reactor concentration histories. In this paper, the authors model ion-exchange column performance using effective diffusivities determined from batch kinetic experiments. This technique is preferable because the batch experiments are easier, faster, and cheaper to perform than column experiments. They also extend these ideas to multicomponent systems. Finally, they evaluate the ability of the equilibrium model to predict data for IE-911.

  19. Ion Exchanged, Glass Laminates that Exhibit a Threshold Strength

    DTIC Science & Technology

    2006-07-10

    tests. The glass was then annealed at 550 ’C for 8hr to remove any residual stress. The ion exchange process was accomplished in a vertical clam ...bonded together (described below) before the ion exchange. Hence, when the bilayer plate was separated using a razor blade (described below), each...strain energy release rate for the bonded interface using the double cantilever beam test configuration. As detailed by Maszara et. al., 19 a razor blade

  20. Samarium Ion Exchanged Montmorillonite for High Temperature Cumene Cracking Reaction

    NASA Astrophysics Data System (ADS)

    Binitha, N. N.; Silija, P. P.; Suraj, V.; Yaakob, Z.; Sugunan, S.

    2011-02-01

    Montmorillonite clay is cation exchanged with samarium and its catalytic influence in cumene cracking reaction is investigated. Effect of exchange with sodium ions on further exchange with samarium ions is also noted. Acidity measurements are done using Temperature Programmed Desorption (TPD) of ammonia. The retention of basic structure is proved from FTIR spectra and XRD patterns. Elemental analysis result shows that samarium exchange has occurred, which is responsible for the higher catalytic activity. Surface area and pore volume remains more or less unaffected upon exchange. Thermogravimetric analysis indicates the enhanced thermal stability on exchanging. Cumene cracking reaction is carried out at atmospheric pressure in a fixed bed glass reactor at 673 K. The predominance of Brønsted acidity is confirmed from high selectivity to benzene.

  1. Localized Hydration in Lyophilized Myoglobin by Hydrogen-Deuterium Exchange Mass Spectrometry. 2. Exchange Kinetics

    PubMed Central

    Sophocleous, Andreas M.; Topp, Elizabeth M.

    2012-01-01

    Solid-state hydrogen deuterium exchange with mass spectrometric analysis (ssHDX) is a promising method for characterizing proteins in amorphous solids. Though analysis of HDX kinetics is informative and well-established in solution, application of these methods to solid samples is complicated by possible heterogeneities in the solid. The studies reported here provide a detailed analysis of the kinetics of hydration and ssHDX for equine myoglobin (Mb) in solid matrices containing sucrose or mannitol. Water sorption was rapid relative to ssHDX, indicating that ssHDX kinetics was not limited by bulk water transport. Deuterium uptake in solids was well-characterized by a bi-exponential model; values for regression parameters provided insight into differences between the two solid matrices. Analysis of the widths of peptide mass envelopes revealed that in solution, an apparent EX2 mechanism prevails, consistent with native conformation of the protein. In contrast, in mannitol-containing samples, a smaller non-native subpopulation exchanges by an EX1-like mechanism. Together, the results indicate that the analysis of ssHDX kinetic data and the widths of peptide mass envelopes are useful in screening solid formulations of protein drugs for the presence of non-native species that cannot be detected by amide I FTIR. PMID:22352990

  2. MODELING RESULTS FROM CESIUM ION EXCHANGE PROCESSING WITH SPHERICAL RESINS

    SciTech Connect

    Nash, C.; Hang, T.; Aleman, S.

    2011-01-03

    Ion exchange modeling was conducted at the Savannah River National Laboratory to compare the performance of two organic resins in support of Small Column Ion Exchange (SCIX). In-tank ion exchange (IX) columns are being considered for cesium removal at Hanford and the Savannah River Site (SRS). The spherical forms of resorcinol formaldehyde ion exchange resin (sRF) as well as a hypothetical spherical SuperLig{reg_sign} 644 (SL644) are evaluated for decontamination of dissolved saltcake wastes (supernates). Both SuperLig{reg_sign} and resorcinol formaldehyde resin beds can exhibit hydraulic problems in their granular (nonspherical) forms. SRS waste is generally lower in potassium and organic components than Hanford waste. Using VERSE-LC Version 7.8 along with the cesium Freundlich/Langmuir isotherms to simulate the waste decontamination in ion exchange columns, spherical SL644 was found to reduce column cycling by 50% for high-potassium supernates, but sRF performed equally well for the lowest-potassium feeds. Reduced cycling results in reduction of nitric acid (resin elution) and sodium addition (resin regeneration), therefore, significantly reducing life-cycle operational costs. These findings motivate the development of a spherical form of SL644. This work demonstrates the versatility of the ion exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. The value of a resin with increased selectivity for cesium over potassium can be assessed for further development.

  3. Differential kinetic physics of solar-wind minor ions

    NASA Astrophysics Data System (ADS)

    Perrone, Denise; Valentini, Francesco; Servidio, Sergio; Stabile, Sara; Pezzi, Oreste; Sorriso-Valvo, Luca; De Marco, Rossana; Marcucci, Federica; Brienza, Daniele; Bruno, Roberto; Lavraud, Benoit; Retinò, Alessandro; Vaivads, Andris; Consolini, Giuseppe; De Keyser, Johan; Salatti, Mario; Veltri, Pierluigi

    2017-04-01

    The solar wind, although predominantly constituted of protons, is also made up of a finite amount of alpha particles, together with a few percent of heavier ions. The kinetic properties of heavy ions in the solar wind are known to behave in a well organized way under most solar-wind flow conditions: their speeds are faster than that of hydrogen by about the local Alfvén speed, and their kinetic temperatures are more than proportional to their mass. Preferential heating and acceleration of heavy ions in the solar wind and corona represent a long-standing theoretical problem in space physics, and are distinct experimental signatures of kinetic processes occurring in collisionless plasmas. However, due to very scarce measurements of heavy ions at time resolutions comparable with their kinetic scales, energy partition between species in turbulent plasma dissipation is basically unexplored. For the moment, most of the information comes from numerical simulations and a crucial support is given by self-consistent, fully nonlinear Vlasov models. Here, hybrid Vlasov-Maxwell simulations are used to investigate the role of kinetic effects in a two-dimensional turbulent multi-ion plasma, composed of kinetic protons and alpha particles, and fluid electrons. The response of different ion species to the fluctuating electromagnetic fields appears to be different. In particular, a significant differential heating of alpha particles with respect to protons is observed, localized nearby the peaks of ion vorticity and where strong deviations from thermodynamic equilibrium are recovered. Then, the understanding of the complex process of particle heating results strongly related to the study of the non-Maxwellian features on the three-dimensional ion velocity distributions. These numerical results highlight the importance for the future space missions to provide detailed ion measurements to make a significant step forward in the problem of heating in turbulent space plasmas.

  4. Simulation study of overtaking of ion-acoustic solitons in the fully kinetic regime

    NASA Astrophysics Data System (ADS)

    Hosseini Jenab, S. M.; Spanier, F.

    2017-03-01

    The overtaking collisions of ion-acoustic solitons in the presence of trapping effects of electrons are studied based on a fully kinetic simulation approach. The method is able to provide all the kinetic details of the process alongside the fluid-level quantities self consistently. Solitons are produced naturally by utilizing the chain formation phenomenon, and then are arranged in a new simulation box to test the different scenarios of overtaking collisions. Three achievements are reported here. First, simulations prove the long-time life span of the ion-acoustic solitons in the presence of trapping effect of electrons (kinetic effects), which serves as the benchmark of the simulation code. Second, their stability against overtaking mutual collisions is established by creating collisions between solitons with different number and shapes of trapped electrons, i.e., different trapping parameter. Finally, details of solitons during collisions for both ions and electrons are provided on both fluid and kinetic levels. These results show that on the kinetic level, trapped electron population accompanying each of the solitons are exchanged between the solitons during the collision. Furthermore, the behavior of electron holes accompanying solitons contradicts the theory about the electron holes interaction developed based on kinetic theory. They also show behaviors much different from other electron holes witnessed in processes such as nonlinear Landau damping (Bernstein-Greene-Kruskal -BGK- modes) or beam-plasma interaction (like two-beam instability).

  5. Central metal ion exchange in a coordination polymer based on lanthanide ions and di(2-ethylhexyl)phosphoric acid: exchange rate and tunable affinity.

    PubMed

    Tasaki-Handa, Yuiko; Abe, Yukie; Ooi, Kenta; Tanaka, Mikiya; Wakisaka, Akihiro

    2014-01-01

    In this paper the exchange of lanthanide(III) ions (Ln(3+)) between a solution and a coordination polymer (CP) of di(2-ethylhexyl)phosphoric acid (Hdehp), [Ln(dehp)3], is studied. Kinetic and selectivity studies suggest that a polymeric network of [Ln(dehp)3] has different characteristics than the corresponding monomeric complex. The reaction rate is remarkably slow and requires over 600 h to reach in nearly equilibrium, and this can be explained by the polymeric crystalline structure and high valency of Ln(3+). The affinity of the exchange reaction reaches a maximum with the Ln(3+) possessing an ionic radius 7% smaller than that of the central Ln(3+), therefore, the affinity of the [Ln(dehp)3] is tunable based on the choice of the central metal ion. Such unique affinity, which differs from the monomeric complex, can be explained by two factors: the coordination preference and steric strain caused by the polymeric structure. The latter likely becomes predominant for Ln(3+) exchange when the ionic radius of the ion in solution is smaller than the original Ln(3+) by more than 7%. Structural studies suggest that the incoming Ln(3+) forms a new phase though an exchange reaction, and this could plausibly cause the structural strain. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Fishbone mode excitation in the ion kinetic regime

    SciTech Connect

    Shi, B.; Sui, G. |

    1997-08-01

    By solving the dispersion relation in the ion kinetic regime, it is found that the threshold of the plasma beta value for exciting the ion-fishbone mode is lowered. Thus, for most of the present-day tokamaks where the Bussac criterion [Bussac {ital et al.}, Phys. Rev. Lett. {bold 35}, 1638 (1975)] is not satisfied, it will still be possible to excite the ion-fishbone mode. {copyright} {ital 1997 American Institute of Physics.}

  7. The kinetics of energetic O‑ ions in oxygen discharge plasmas

    NASA Astrophysics Data System (ADS)

    Ponomarev, A. A.; Aleksandrov, N. L.

    2017-04-01

    Monte Carlo simulation was used to study the translational relaxation of energetic O‑ ions produced by dissociative electron attachment to O2 molecules in oxygen plasmas in a strong electric field. Initial O‑ ions have rather high energies and are more reactive than the ions reaching equilibrium with the electric field. Therefore, there is a noticeable probability that the energetic O‑ ions participate in endothermic reactions prior to energy relaxation of these ions. The probabilities of charge exchange, electron detachment and ion impact vibrational excitation of O2 molecules were calculated versus the reduced electric field. It was shown that up to 6% of energetic O‑ ions produced in oxygen by dissociative electron attachment to O2 molecules are rapidly transformed to {{{{O}}}2}- ions due to charge exchange collisions. The probability of electron detachment from energetic O‑ ions and the probability of vibrational excitation were smaller that the probability of charge exchange. Estimates showed that the increase in the effective rates of the ion–molecule reactions due to high reactivity of energetic O‑ ions can be important in oxygen plasmas for reduced electric fields of 50–100 Td.

  8. Exchange Kinetics of a Hydrophobic Ligand Binding Protein

    NASA Astrophysics Data System (ADS)

    Vaughn, Jeff; Stone, Martin

    2002-03-01

    Conformational fluctuations of proteins are thought to be important for determining the functional roles in biological activity. In some cases, the rates of these conformational changes may be directly correlated to, for example, the rates of catalysis or ligand binding. We are studying the role of conformational fluctuations in the binding of small volatile hydrophobic pheromones by the mouse major urinary proteins (MUPs). Communication among mice occurs, in part, with the MUP-1 protein. This urinary protein binds pheromones as a way to increase the longevity of the pheromone in an extracellular environment. Of interest is that the crystal structure of MUP-1 with a pheromone ligand shows the ligand to be completely occluded from the solvent with no obvious pathway to enter or exit. This suggests that conformational exchange of the protein may be required for ligand binding and release to occur. We hypothesize that the rate of conformational exchange may be a limiting factor determining the rate of ligand association and dissociation. By careful measurement of the on- and off-rates of ligand binding and the rates of conformational changes of the protein, a more defined picture of the interplay between protein structure and function can be obtained. To this end, heteronuclear saturation transfer, ^15N-exchange and ^15N dynamics experiments have been employed to probe the kinetics of ligand binding to MUP-1.

  9. Ion momentum and energy transfer rates for charge exchange collisions

    NASA Technical Reports Server (NTRS)

    Horwitz, J.; Banks, P. M.

    1973-01-01

    The rates of momentum and energy transfer have been obtained for charge exchange collisions between ion and neutral gases having arbitrary Maxwellian temperatures and bulk transport velocities. The results are directly applicable to the F-region of the ionosphere where 0+ - 0 charge is the dominant mechanism affecting ion momentum and energy transfer.

  10. ELUTION OF URANIUM VALUES FROM ION EXCHANGE RESINS

    DOEpatents

    Kennedy, R.H.

    1959-11-24

    A process is described for eluting complex uranium ions absorbed on ion exchange resins. The resin is subjected to the action of an aqueous eluting solution contuining sulfuric acid and an alkali metal, ammonium, or magnesium chloride or nitrate, the elution being carried out until the desired amount of the uranium is removed from the resin.

  11. Nonexponential kinetics of ion pair dissociation in electrofreezing water.

    PubMed

    Alaghemandi, Mohammad; Koller, Volkmar; Green, Jason R

    2017-10-04

    Temporally- or spatially-heterogeneous environments can participate in many kinetic processes, from chemical reactions and self-assembly to the forced dissociation of biomolecules. Here, we simulate the molecular dynamics of a model ion pair forced to dissociate in an explicit, aqueous solution. Triggering dissociation with an external electric field causes the surrounding water to electrofreeze and the ion pair population to decay nonexponentially. To further probe the role of the aqueous environment in the kinetics, we also simulate dissociation events under a purely mechanical force on the ion pair. In this case, regardless of whether the surrounding water is a liquid or already electrofrozen, the ion pair population decays exponentially with a well-defined rate constant that is specific to the medium and applied force. These simulation data, and the rate parameters we extract, suggest the disordered kinetics in an electrofreezing medium are a result of the comparable time scales of two concurrent processes, electrofreezing and dissociation.

  12. Information hidden in the velocity distribution of ions and the exact kinetic Bohm criterion

    NASA Astrophysics Data System (ADS)

    Tsankov, Tsanko V.; Czarnetzki, Uwe

    2017-05-01

    Non-equilibrium distribution functions of electrons and ions play an important role in plasma physics. A prominent example is the kinetic Bohm criterion. Since its first introduction it has been controversial for theoretical reasons and due to the lack of experimental data, in particular on the ion distribution function. Here we resolve the theoretical as well as the experimental difficulties by an exact solution of the kinetic Boltzmann equation including charge exchange collisions and ionization. This also allows for the first time non-invasive measurement of spatially resolved ion velocity distributions, absolute values of the ion and electron densities, temperatures, and mean energies as well as the electric field and the plasma potential in the entire plasma. The non-invasive access to the spatially resolved distribution functions of electrons and ions is applied to the problem of the kinetic Bohm criterion. Theoretically a so far missing term in the criterion is derived and shown to be of key importance. With the new term the validity of the kinetic criterion at high collisionality and its agreement with the fluid picture are restored. All findings are supported by experimental data, theory and a numerical model with excellent agreement throughout.

  13. Metal ion-exchange on the muscovite mica surface

    NASA Astrophysics Data System (ADS)

    de Poel, Wester; Vaessen, Sarah L.; Drnec, Jakub; Engwerda, Anthonius H. J.; Townsend, Eleanor R.; Pintea, Stelian; de Jong, Aryan E. F.; Jankowski, Maciej; Carlà, Francesco; Felici, Roberto; Elemans, Johannes A. A. W.; van Enckevort, Willem J. P.; Rowan, Alan E.; Vlieg, Elias

    2017-11-01

    The surface potassium ions of muscovite mica were exchanged for several different metal ions from aqueous solution (Ag, Ca, V, Mn, Fe, Ni, Cu, Zn, Co, and Cd). The surfaces were rinsed in water, dried under nitrogen atmosphere, and subsequently analysed using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and, for half the systems, surface X-ray diffraction (SXRD). XPS and SXRD confirmed the presence of the different metal ions at the muscovite mica surface, with a partial monolayer of the monovalent and divalent ions present on the surface. No counter ions from the used salts were detected. AFM revealed that Ni-, and Fe-terminated muscovite mica surfaces were partially covered by nanoparticles, most likely consisting of metal (hydr)oxide. The exchanged ions remained on the surface after rinsing with ultra pure water three times. SXRD showed that Cd and Ag have a lower affinity for the muscovite mica surface than Cu, Ca, and Mn.

  14. Removal of chromium from electroplating industry effluents by ion exchange resins.

    PubMed

    Cavaco, Sofia A; Fernandes, Sandra; Quina, Margarida M; Ferreira, Licínio M

    2007-06-18

    Effluent discharged from the chromium electroplating industry contains a large number of metals, including chromium, copper, nickel, zinc, manganese and lead. The ion exchange process is an alternative technique for application in the treatment of industrial wastewater containing heavy metals and indeed it has proven to be very promising in the removal and recovery of valuable species. The main objective of the present work is to evaluate the performance of commercial ion exchange resins for removing chromium trivalent from industrial effluents, and for this purpose two resins were tested: a chelating exchange resin (Diaion CR11) and a weak cationic resin (Amberlite IRC86). In order to evaluate the sorption capacity of the resins some equilibrium experiments were carried out, being the temperature and pH the main variables considered. The chromium solutions employed in the experiments were synthetic solutions and industrial effluents. In addition, a transient test was also performed as an attempt to understand the kinetic behaviour of the process.

  15. Desalination of brackish waters using ion exchange media.

    SciTech Connect

    Pless, Jason D.; Krumhansl, James Lee; Nenoff, Tina Maria; Voigt, James A.; Phillips, Mark L. F.; Axness, Marlene; Moore, Diana Lynn

    2005-01-01

    An environmentally friendly method and materials study for desalinating inland brackish waters (i.e., coal bed methane produced waters) using a set of ion-exchange materials is presented. This desalination process effectively removes anions and cations in separate steps with minimal caustic waste generation. The anion-exchange material, hydrotalcite (HTC), exhibits an ion-exchange capacity (IEC) of {approx} 3 mequiv g{sup -1}. The cation-exchange material, an amorphous aluminosilicate permutite-like material, (Na{sub x+2y}Al{sub x}Si{sub 1-x}O{sub 2+y}), has an IEC of {approx}2.5 mequiv g{sup -1}. These ion-exchange materials were studied and optimized because of their specific ion-exchange capacity for the ions of interest and their ability to function in the temperature and pH regions necessary for cost and energy effectiveness. Room temperature, minimum pressure column studies (once-pass through) on simulant brackish water (total dissolved solids (TDS) = 2222 ppm) resulted in water containing TDS = 25 ppm. A second once-pass through column study on actual produced water (TDS = {approx}11,000) with a high carbonate concentration used an additional lime softening step and resulted in a decreased TDS of 600 ppm.

  16. Desalination of brackish waters using ion-exchange media

    SciTech Connect

    Pless, J.D.; Philips, M.L.F.; Voigt, J.A.; Moore, D.; Axness, M.; Krumhansl, J.L.; Nenoff, T.M.

    2006-06-21

    An environmentally friendly method and materials study for desalinating inland brackish waters (i.e., coal bed methane produced waters) using a set of ion-exchange materials is presented. This desalination process effectively removes anions and cations in separate steps with minimal caustic waste generation. The anion-exchange material, hydrotalcite (HTC), exhibits an ion-exchange capacity (IEC) of around 3 mequiv g{sup -1}. The cation-exchange material, an amorphous aluminosilicate permutite-like material, (Na{sub x}+2yAl{sub x}Si{sub 1}-xO{sub 2+y}), has an IEC of around to 2.5 mequiv g{sup -1}. These ion-exchange materials were studied and optimized because of their specific ion-exchange capacity for the ions of interest and their ability to function in the temperature and pH regions necessary for cost and energy effectiveness. Room temperature, minimum pressure column studies (once-pass through) on simulant brackish water (total dissolved solids (TDS) = 2222 ppm) resulted in water containing TDS = 25 ppm. A second once-pass through column study on actual produced water (TDS = similar to 11 000) with a high carbonate concentration used an additional lime softening step and resulted in a decreased TDS of 600 ppm.

  17. A bounce-averaged kinetic model of the ring current ion population

    NASA Technical Reports Server (NTRS)

    Jordanova, V. K.; Kozyra, J. U.; Khazanov, G. V.; Nagy, A. F.; Rasmussen, C. E.; Fok, M.-C.

    1994-01-01

    A bounced-averaged ring current kinetic model for arbitrary pitch angle, including losses due to charge exchange and Coulomb collisions along ion drift paths, is developed and solved numerically. Results from simplifield model runs, intended to illustrate the effects of adiabatic drifts and collisional losses on the proton population, are presented. The processes of: (1) particle acceleration under the conditions of time-independent magnetospheric electric fields; (2) a predominant loss of particles with small pitch angles due to charge exchange; and (3) a buildup of a low-energy population caused by the Coulomb drag energy degradation, are discussed.

  18. Rate theory on water exchange in aqueous uranyl ion

    NASA Astrophysics Data System (ADS)

    Dang, Liem X.; Vo, Quynh N.; Nilsson, Mikael; Nguyen, Hung D.

    2017-03-01

    We report a classical rate theory approach to predict the exchange mechanism that occurs between water and aqueous uranyl ion. Using our water and ion-water polarizable force field and molecular dynamics techniques, we computed the potentials of mean force for the uranyl ion-water pair as a function of different pressures at ambient temperature. These potentials of mean force were used to calculate rate constants using transition rate theory; the transmission coefficients also were examined using the reactive flux method and Grote-Hynes approach. The computed activation volumes are positive; thus, the mechanism of this particular water-exchange is a dissociative process.

  19. Sorption of sunset yellow dye by weak base anion exchanger-kinetic and equilibrium studies.

    PubMed

    Wawrzkiewicz, Monika

    2011-01-01

    The sorption equilibrium and kinetics of Sunset Yellow dye in aqueous solutions on the weak base anion exchange resin Amberlite FPA51 were examined in this paper. The influences of phase contact time, solution pH, initial dye concentration and temperature were studied by the batch method. The amounts of dye sorbed at equilibrium changed from 9.9 to 48.7 mg/g with increasing initial dye concentration in the range 100-500 mg/L. The experimental data were analysed by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models of adsorption. The maximum monolayer capacity was 130.6 mg/g. The sorption free energy was equal to 14.6 kJ/mol and revealed the nature of the ion exchange mechanism in this system. The kinetic data were modelled using the pseudo-first-order, pseudo-second-order (types 1-5) and intraparticle diffusion equations. The experimental data were well described by types 1-3 of the pseudo-second-order kinetic model.

  20. Kinetic energy distributions of ions after surface collisions

    SciTech Connect

    Short, R.T.; Todd, P.J.; Grimm, C.C.

    1991-01-01

    As a part of the development of an organic ion microprobe, to be used for imaging of particular organic compounds in biological tissue, various methods of quadrupole-based tandem mass spectroscopy (MS/MS) have been investigated. High transmission efficiency is essential for the success of the organic ion microprobe, due to expected low analyte concentrations in biological tissue and the potential for sample damage from prolonged exposure to the primary ion beam. MS/MS is necessary for organic ion imaging because of the complex nature of the biological matrices. The goal of these studies of was to optimize the efficiency of daughter ion production and transmission by first determining daughter ion properties and then designing ion optics based on those properties. The properties of main interest are daughter ion kinetic energy and angular distribution. 1 fig.

  1. Small-Scale Ion Exchange Removal of Cesium and Technetium from Hanford Tank 241-AN-103

    SciTech Connect

    Hassan, N.M.

    2000-07-27

    The pretreatment process for BNFL, Inc.'s Hanford River Protection Project is to provide decontaminated low activity waste and concentrated eluate streams for vitrification into low activity and high level waste glass, respectively. The pretreatment includes sludge washing, filtration, precipitation, and ion exchange processes to remove entrained solids, cesium, transuranics, technetium, and strontium. The ion exchange removal of cesium (Cs) and technetium (Tc) ions is accomplished by using SuperLig 644, and 639 resins from IBC Advanced Technologies, American Fork, Utah. The resins were shown to selectively remove cesium and technetium (as pertechnetate), from alkaline salt solutions. The efficiency of ion exchange column loading and elution is a complex function involving feed compositions, equilibrium and kinetic behavior of ion exchange resins, diffusion, and the ionic strength and pH of the aqueous solution. A previous experimental program completed at the Savannah River Technology Center demonstrated the conceptualized flow sheet parameters with a similar Hanford tank sample (241-AW-101). Those experiments included determination of Cs and Tc batch distribution coefficients by SuperLig 644 and 639 resins and demonstration of small-scale column breakthrough and elution. The experimental findings were used in support of preliminary design bases and pretreatment flow sheet development by BNFL, Inc.

  2. The Role of Ion Exchange Membranes in Membrane Capacitive Deionisation.

    PubMed

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

    2017-09-14

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

  3. The Role of Ion Exchange Membranes in Membrane Capacitive Deionisation

    PubMed Central

    Hassanvand, Armineh; Wei, Kajia; Talebi, Sahar

    2017-01-01

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

  4. Electrical and magnetic properties of ion-exchangeable layered ruthenates

    SciTech Connect

    Sugimoto, Wataru . E-mail: wsugi@shinshu-u.ac.jp; Omoto, Masashi; Yokoshima, Katsunori; Murakami, Yasushi; Takasu, Yoshio

    2004-12-01

    An ion-exchangeable ruthenate with a layered structure, K{sub 0.2}RuO{sub 2.1}, was prepared by solid-state reactions. The interlayer cation was exchanged with H{sup +}, C{sub 2}H{sub 5}NH{sub 3}{sup +}, and ((C{sub 4}H{sub 9}){sub 4}N{sup +}) through proton-exchange, ion-exchange, and guest-exchange reactions. The electrical and magnetic properties of the products were characterized by DC resistivity and susceptibility measurements. Layered K{sub 0.2}RuO{sub 2.1} exhibited metallic conduction between 300 and 13K. The products exhibited similar magnetic behavior despite the differences in the type of interlayer cation, suggesting that the ruthenate sheet in the protonated form and the intercalation compounds possesses metallic nature.

  5. Quantitative ion-exchange separation of plutonium from impurities

    SciTech Connect

    Pietri, C.E.; Freeman, B.P.; Weiss, J.R.

    1981-09-01

    The methods used at the New Brunswick Laboratory for the quantitative ion exchange separation of plutonium from impurities prior to plutonium assay are described. Other ion exchange separation procedures for impurity determination and for isotopic abundance measurements are given. The primary technique used consists of sorption of plutonium(IV) in 8N HNO/sub 3/ on Dowex-1 anion exchange resin and elution of the purified plutonium with 0.3N HCl-0.01N HF. Other methods consist of the anion exchange separation of plutonium(IV) in 12N HCl and the cation exchange separation of plutonium(III) in 0.2 N HNO/sub 3/. The application of these procedures to the subsequent assay of plutonium, isotopic analysis, and impurity determination is described.

  6. ION EXCHANGE PERFORMANCE OF TITANOSILICATES, GERMANATES AND CARBON NANOTUBES

    SciTech Connect

    Alsobrook, A. N.; Hobbs, D. T.

    2013-04-24

    This report presents a summary of testing the affinity of titanosilicates (TSP), germanium-substituted titanosilicates (Ge-TSP) and multiwall carbon nanotubes (MWCNT) for lanthanide ions in dilute nitric acid solution. The K-TSP ion exchanger exhibited the highest affinity for lanthanides in dilute nitric acid solutions. The Ge-TSP ion exchanger shows promise as a material with high affinity, but additional tests are needed to confirm the preliminary results. The MWCNT exhibited much lower affinities than the K-TSP in dilute nitric acid solutions. However, the MWCNT are much more chemically stable to concentrated nitric acid solutions and, therefore, may candidates for ion exchange in more concentrated nitric acid solutions. This technical report serves as the deliverable documenting completion of the FY13 research milestone, M4FT-13SR0303061 – measure actinide and lanthanide distribution values in nitric acid solutions with sodium and potassium titanosilicate materials.

  7. Kinetics of Isovalent (Cd(2+)) and Aliovalent (In(3+)) Cation Exchange in Cd1-xMnxSe Nanocrystals.

    PubMed

    Chakraborty, Pradip; Jin, Yu; Barrows, Charles J; Dunham, Scott T; Gamelin, Daniel R

    2016-10-05

    Ion exchange, in which an in-diffusing ion replaces a lattice ion, has been widely exploited as a synthetic tool for semiconductor doping and solid-to-solid chemical transformations, both in bulk and at the nanoscale. Here, we present a systematic investigation of cation-exchange reactions that involve the displacement of Mn(2+) from CdSe nanocrystals by Cd(2+) or In(3+). For both incoming cations, Mn(2+) displacement is spontaneous but thermally activated, following Arrhenius behavior over a broad experimental temperature range. At any given temperature, cation exchange by In(3+) is approximately 2 orders of magnitude faster than that by Cd(2+), illustrating a critical dependence on the incoming cation. Quantitative analysis of the kinetics data within a Fick's-law diffusion model yields diffusion barriers (ED) and limiting diffusivities (D0) for both incoming ions. Despite their very different kinetics, indistinguishable diffusion barriers of ED ≈ 1.1 eV are found for both reactions (In(3+) and Cd(2+)). A dramatically enhanced diffusivity is found for Mn(2+) cation exchange by In(3+). Overall, these findings provide unique experimental insights into cation diffusion within colloidal semiconductor nanocrystals, contributing to our fundamental understanding of this rich and important area of nanoscience.

  8. Phenol removal from aqueous solution by adsorption and ion exchange mechanisms onto polymeric resins.

    PubMed

    Caetano, Michelle; Valderrama, César; Farran, Adriana; Cortina, José Luis

    2009-10-15

    The removal of phenol from aqueous solution was evaluated by using a nonfunctionalized hyper-cross-linked polymer Macronet MN200 and two ion exchange resins, Dowex XZ (strong anion exchange resin) and AuRIX 100 (weak anion exchange). Equilibrium experimental data were fitted to the Langmuir and Freundlich isotherms at different pHs. The Langmuir model describes successfully the phenol removal onto the three resins. The extent of the phenol adsorption was affected by the pH of the solution; thus, the nonfunctionalized resin reported the maximum loading adsorption under acidic conditions, where the molecular phenol form predominates. In contrast both ion exchange resins reported the maximum removal under alkaline conditions where the phenolate may be removed by a combined effect of both adsorption and ion exchange mechanisms. A theoretical model proposed in the literature was used to fit the experimental data and a double contribution was observed from the parameters obtained by the model. Kinetic experiments under different initial phenol concentrations and under the best pH conditions observed in the equilibrium experiments were performed. Two different models were used to define the controlling mechanism of the overall adsorption process: the homogeneous particle diffusion model and the shell progressive model fit the kinetic experimental data and determined the resin phase mechanism as the rate-limiting diffusion for the phenol removal. Resins charged after the kinetic experiments were further eluted by different methods. Desorption of nonfunctionalized resin was achieved by using the solution (50% v/v) of methanol/water with a recovery close to 90%. In the case of the ion exchange resins the desorption process was performed at different pHs and considering the effect of the competitive ion Cl-. The desorption processes were controlled by the ion exchange mechanism for Dowex XZ and AuRIX 100 resins; thus, no significant effect for the addition of Cl- under acidic

  9. H/D exchange of gas phase bradykinin ions in a linear quadrupole ion trap.

    PubMed

    Mao, Dunmin; Douglas, D J

    2003-02-01

    The gas phase H/D exchange reaction of bradykinin ions, as well as fragment ions of bradykinin generated through collisions in an orifice skimmer region, have been studied with a linear quadrupole ion trap (LIT) reflectron time-of-flight (rTOF) mass spectrometer system. The reaction in the trap takes only tens of seconds at a pressure of few mTorr of D2O or CD3OD. The exchange rate and hydrogen exchange level are not sensitive to the trapping q value over a broad range, provided q is not close to the stability boundary (q = 0.908). The relative rates and hydrogen exchange levels of protonated and sodiated +1 and +2 ions are similar to those observed previously by others with a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer system. The doubly and triply protonated ions show multimodal isotopic distributions, suggesting the presence of several different conformations. The y fragment ions show greater exchange rates and levels than a or b ions, and when water or ammonia is lost from the fragment ions, no exchange is observed.

  10. Modeling ion exchange in glass with concentration-dependent diffusion coefficients and mobilities

    NASA Astrophysics Data System (ADS)

    Lupascu, Alexandru I.; Kevorkian, Antoine P.; Boudet, Thierry; Saint-Andre, Francoise; Persegol, Dominique; Levy, Michel

    1996-06-01

    Multimode buried waveguides made in silicate glass by field-assisted ion exchange present very asymmetric profiles. We show how this phenomenon originates in the large dependence of the kinetics on the local ion concentrations. For this purpose, we derive an interdiffusion equation that includes the effects of concentration-dependent diffusion coefficients and mobilities. We show how to deduce this dependence from measurements on ion- diffused samples. The maximum concentration of the incoming ions is computed from surface equilibrium conditions and is used in the interdiffusion equation as a limiting parameter for coefficient variations. To control the model accuracy for surface as well as buried waveguides, we measure ion profiles with three independent methods: M-lines, scanning electron microscopy, and near-field refractometry. When applied to Ag+-Na+ exchange in silicate glass, the model yields theoretical estimations in good agreement with experiments. This approach underlines the fundamentally nonlinear process that takes place during ion exchange and is also valuable to properly model singlemode waveguide fabrication.

  11. Properties of a Novel Ion-Exchange Film

    NASA Technical Reports Server (NTRS)

    Street, Kenneth W.; Hill, Carol M.; Philipp, Warren H.; Tanner, Stephen P.; Gorse, Joseph; Lusk, Amy; Taylor, Jason; Dickens, Jason

    2002-01-01

    A new ion-exchange material (based on polyacrylic acid) and some of its analytical applications have been reported. This paper contains data on the ion-exchange properties of the film form of the material and its potential application to the decontamination of waste water and drinking water. The film has a high exchange capacity of 5 to 6 meq/g and a pK(sub a) of 5.7. The calcium form is the most effective for removing metal ions from solution, and the optimum pH range is between 5 and 7. The exchange rates are slower for the film than for bead and powder forms of the ion-exchange material; otherwise, the properties are similar. The film is effective when hard water solutions are employed and also when metal ions are in the complex matrix of waste water from electroplating. The film can be used in flow systems having a flow channel large enough to allow passage of turbid solutions.

  12. Properties of a Novel Ion-Exchange Film

    NASA Technical Reports Server (NTRS)

    Street, Kenneth W.; Hill, Carol M.; Philipp, Warren H.; Tanner, Stephen P.; Gorse, Joseph; Lusk, Amy; Taylor, Jason; Dickens, Jason

    2004-01-01

    A new ion-exchange material (based on polyacrylic acid) and some of its analytical applications have been reported. This paper contains data on the ion-exchange properties of the film form of the material and its potential application to the decontamination of waste water and drinking water. The film has a high exchange capacity of 5 to 6 meq/g and a pK(sub a) of 5.7. The calcium form is the most effective for removing metal ions from solution, and the optimum pH range is between 5 and 7. The exchange rates are slower for the film than for bead and powder forms of the ion-exchange material; otherwise, the properties are similar. The film is effective when hard water solutions are employed and also when metal ions are in the complex matrix of waste water from electroplating. The film can be used in flow systems having a flow channel large enough to allow passage of turbid solutions.

  13. Cementation of residue ion exchange resins at Rocky Flats

    SciTech Connect

    Dustin, D.F.; Beckman, T.D.; Madore, C.M.

    1998-03-03

    Ion exchange resins have been used to purify nitric acid solutions of plutonium at Rocky Flats since the 1950s. Spent ion exchange resins were retained for eventual recovery of residual plutonium, typically by incineration followed by the aqueous extraction of plutonium from the resultant ash. The elimination of incineration as a recovery process in the late 1980s and the absence of a suitable alternative process for plutonium recovery from resins led to a situation where spent ion exchange resins were simply placed into temporary storage. This report describes the method that Rocky Flats is currently using to stabilize residue ion exchange resins. The objective of the resin stabilization program is: (1) to ensure their safety during interim storage at the site, and (2) to prepare them for ultimate shipment to the Waste Isolation Pilot Plant (WIPP) in New Mexico. Included in the discussion is a description of the safety concerns associated with ion exchange resins, alternatives considered for their stabilization, the selection of the preferred treatment method, the means of implementing the preferred option, and the progress to date.

  14. Pulsed ion beam investigation of the kinetics of surface reactions

    NASA Technical Reports Server (NTRS)

    Horton, C. C.; Eck, T. G.; Hoffman, R. W.

    1989-01-01

    Pulsed ion beam measurements of the kinetics of surface reactions are discussed for the case where the width of the ion pulse is comparable to the measured reaction time, but short compared to the time between successive pulses. Theoretical expressions are derived for the time dependence of the ion-induced signals for linear surface reactions. Results are presented for CO emission from surface carbon and CF emission from Teflon induced by oxygen ion bombardment. The strengths and limitations of this technique are described.

  15. Ion exchange in KTiOPO4 crystals irradiated by copper and hydrogen ions.

    PubMed

    Zhang, Ruifeng; Lu, Fei; Lian, Jie; Liu, Hanping; Liu, Xiangzhi; Lu, Qingming; Ma, Hongji

    2008-05-12

    Cs(+)-K+ ion exchanges were produced on KTiOPO4 crystals which is prior irradiated by Cu+ can H+ ions. The energy and dose of implanted Cu+ ions are 1.5 MeV and 0.5 x 10(14) ions/cm2, and that of H+ are 300 keV and 1 x 10(16) ions/cm2, respectively. The temperature of ions exchange is 430 degrees C, and the time range from 15 minutes to 30 minutes. The prism coupling method is used to measure the dark mode spectra of the samples. Compared with results of ion exchange on the sample without irradiations, both the number of guided mode and its corresponding effective refractive index are decreased. The experimental results indicate that the ion exchange rate closely related with the lattice damage and the damage layers formed in the depth of maximum nuclear energy deposition act as a barrier to block the ions diffuse into the sample and the concentration of defects can modify the speed of ion exchange..

  16. The electrochemical investigation of salts partition with ion exchange membranes.

    PubMed

    Ata, Nejla; Yazicigil, Zafer; Oztekin, Yasemin

    2008-12-15

    The regenaration of acid and base from the solutions containing metallic salts was achieved by salt splitting method (SSM) using not only anion-exchange membranes (AEM) but also cation-exchange membrane (CEM). In these experiments, while the ion exchange membrane was anion-exchange membrane, acid solutions were used as an anolyte and different salts of potassium were used as a catholyte. In addition to these experiments, while the ion exchange membrane was cation-exchange membrane, base solutions were used as a catholyte and different salts of potassium were used as an anolyte. The effects of current density, initial concentrations of anolyte and catholyte solutions, the type of salt solution and the type of the ion-exchange membranes on the recovery ratio of bases and acids were investigated. The results of the experiments were investigated with the Statistical Package for Social Sciences (SPSS) program. The obtained results show that this technique can be used not only for recovering the acid and base wastes of industry but also for removing the impurities in order to obtain pure acids and bases in laboratory conditions.

  17. THERMODYNAMICS OF ION-EXCHANGED NATURAL CLINOPTILOLITE

    EPA Science Inventory

    Natural clinoptilolite from Castle Creek, Idaho, and its cation-exchanged variants (Na-Cpt, NaK-Cpt, K-Cpt, and Ca-Cpt) were studied by high-temperature calorimetry. The hydration enthalpy for all clinoptilolites is about -30 kJ/mol H2O (liquid water reference state) at 25 C. T...

  18. Hydrous oxide ion-exchange compound catalysts

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.

    1990-01-01

    A catalytic material of improved activity which comprises a hydrous, alkali metal or alkaline earth metal or quaternary ammonium titanate, zirconate, niobate, or tantalate, in which the metal or ammonium cations have been exchange with a catalytically effective quantity of a catalyst metal, and which has been subsequently treated with a solution of a Bronsted acid.

  19. THERMODYNAMICS OF ION-EXCHANGED NATURAL CLINOPTILOLITE

    EPA Science Inventory

    Natural clinoptilolite from Castle Creek, Idaho, and its cation-exchanged variants (Na-Cpt, NaK-Cpt, K-Cpt, and Ca-Cpt) were studied by high-temperature calorimetry. The hydration enthalpy for all clinoptilolites is about -30 kJ/mol H2O (liquid water reference state) at 25 C. T...

  20. Ion exchange polymers for anion separations

    DOEpatents

    Jarvinen, Gordon D.; Marsh, S. Fredric; Bartsch, Richard A.

    1997-01-01

    Anion exchange resins including at least two positively charged sites and a ell-defined spacing between the positive sites are provided together with a process of removing anions or anionic metal complexes from aqueous solutions by use of such resins. The resins can be substituted poly(vinylpyridine) and substituted polystyrene.

  1. Ion exchange polymers for anion separations

    DOEpatents

    Jarvinen, G.D.; Marsh, S.F.; Bartsch, R.A.

    1997-09-23

    Anion exchange resins including at least two positively charged sites and a well-defined spacing between the positive sites are provided together with a process of removing anions or anionic metal complexes from aqueous solutions by use of such resins. The resins can be substituted poly(vinylpyridine) and substituted polystyrene.

  2. Electron and ion kinetics in magnetized capacitively coupled plasma source

    SciTech Connect

    Lee, S. H.; You, S. J.; Chang, H. Y.; Lee, J. K.

    2007-05-15

    One-dimensional particle-in-cell Monte Carlo collision simulations of magnetized argon plasmas in an asymmetric capacitively coupled plasma reactor are presented. At low pressure (10 mTorr), electron kinetics are strongly affected by the magnetic field and transitions from nonlocal to local kinetic property occur with increasing magnetic field which are reflected in spatially resolved calculations of the electron-energy probability function. For high-energy electrons, the transition takes place when the energy-relaxation length is smaller than the system length. For low-energy electrons, however, the transition occurs when the electron-diffusion time scale in the energy space is shorter than the spatial-diffusion time scale in coordinate space. These observations are in agreement with experimental data and theoretical calculations deduced from the Boltzmann equation. The ion energy distribution function (IEDF) on the driven electrode changes from the ion-neutral collisional type to the ion-neutral collisionless type with increasing magnetic field strength. The maximum ion energy in the IEDF decreases and the angular spread in the ion angle distribution function slightly increases with increasing magnetic field strength. These changes are explained in terms of the ratio of the ion-transit time to rf frequency, the sheath length, and the mean potential difference between the driven electrode and the plasma. At high pressure (218 mTorr), electron-neutral collisions disrupt electron gyromotion so that the effects of the magnetic field on electron and ion kinetics are greatly reduced.

  3. MINOR ACTINIDE SEPARATIONS USING ION EXCHANGERS OR IONIC LIQUIDS

    SciTech Connect

    Hobbs, D.; Visser, A.; Bridges, N.

    2011-09-20

    This project seeks to determine if (1) inorganic-based ion exchange materials or (2) electrochemical methods in ionic liquids can be exploited to provide effective Am and Cm separations. Specifically, we seek to understand the fundamental structural and chemical factors responsible for the selectivity of inorganic-based ion-exchange materials for actinide and lanthanide ions. Furthermore, we seek to determine whether ionic liquids can serve as the electrolyte that would enable formation of higher oxidation states of Am and other actinides. Experiments indicated that pH, presence of complexants and Am oxidation state exhibit significant influence on the uptake of actinides and lanthanides by layered sodium titanate and hybrid zirconium and tin phosphonate ion exchangers. The affinity of the ion exchangers increased with increasing pH. Greater selectivity among Ln(III) ions with sodium titanate materials occurs at a pH close to the isoelectric potential of the ion exchanger. The addition of DTPA decreased uptake of Am and Ln, whereas the addition of TPEN generally increases uptake of Am and Ln ions by sodium titanate. Testing confirmed two different methods for producing Am(IV) by oxidation of Am(III) in ionic liquids (ILs). Experimental results suggest that the unique coordination environment of ionic liquids inhibits the direct electrochemical oxidation of Am(III). The non-coordinating environment increases the oxidation potential to a higher value, while making it difficult to remove the inner coordination of water. Both confirmed cases of Am(IV) were from the in-situ formation of strong chemical oxidizers.

  4. Kinetic Isotope Effect on Transport Mediated by Clc-Type H+/CL- Exchangers

    NASA Astrophysics Data System (ADS)

    Picollo, Alessandra; Malvezzi, Mattia; Accardi, Alessio

    2013-01-01

    CLC transporters mediate the stoichiometric exchange of 2 Cl- ions for 1 H+ across the membranes of cellular compartments, mostly endosomes and lysosomes. Despite intense biophysical, structural and electrophysiological scrutiny the H+ transfer mechanism of these exchangers remains largely unknown. Previous work showed that two conserved Glutamates define the extremities of the H+ pathway in CLC exchangers. However, we don't know whether H+ transfer between these residues takes place along a series of protonatable moieties, via a Grotthuss mechanism and by diffusion of an H3+O cation and if at any step H+ tunneling plays a role. To differentiate between these possible mechanisms we measured the deuterium kinetic isotope effect on the transport rate of CLC-ec1 and CLC-5, respectively a prokaryotic and a eukaryotic CLC exchanger. We found that transport mediated by both proteins is slowed by ˜20-40% when H2O is replaced by D2O. This result suggests that the rate limiting step for H+ transport takes place along a hydrogen-bonded pathway, possibly formed by water molecules. However, we found that the voltage dependence of CLC-5 inhibition by extracellular H+ is eliminated by this substitution. This suggests that the voltage dependence of this process arises from a mechanism that is exquisitely sensitive to particle mass such as proton tunneling.

  5. Kinetic modeling of auroral ion Outflows observed by the VISIONS sounding rocket

    NASA Astrophysics Data System (ADS)

    Albarran, R. M.; Zettergren, M. D.; Rowland, D. E.; Klenzing, J.; Clemmons, J. H.

    2016-12-01

    The VISIONS (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of the ion outflow below 1000km. Energetic ion data from the VISIONS polar cap boundary crossing show evidence of an ion "pressure cooker" effect whereby ions energized via transverse heating in the topside ionosphere travel upward and are impeded by a parallel potential structure at higher altitudes. VISIONS was also instrumented with an energetic neutral atom (ENA) detector which measured neutral particles ( 50-100 eV energy) presumably produced by charge-exchange with the energized outflowing ions. Hence, inferences about ion outflow may be made via remotely-sensing measurements of ENAs. This investigation focuses on modeling energetic outflowing ion distributions observed by VISIONS using a kinetic model. This kinetic model traces large numbers of individual particles, using a guiding-center approximation, in order to allow calculation of ion distribution functions and moments. For the present study we include mirror and parallel electric field forces, and a source of ion cyclotron resonance (ICR) wave heating, thought to be central to the transverse energization of ions. The model is initiated with a steady-state ion density altitude profile and Maxwellian velocity distribution characterizing the initial phase-space conditions for multiple particle trajectories. This project serves to advance our understanding of the drivers and particle dynamics in the auroral ionosphere and to improve data analysis methods for future sounding rocket and satellite missions.

  6. Small-Scale Ion Exchange Removal of Cesium and Technetium from Hanford Tank 241-AN-102

    SciTech Connect

    Hassan, N.M.

    2000-07-27

    The pretreatment process for BNFL, Inc.'s Hanford River Protection Project is to provide decontaminated low activity waste and concentrated eluate streams for vitrification into low and high activity waste glass, respectively. The pretreatment includes sludge washing, filtration, precipitation, and ion exchange processes to remove entrained solids, cesium, transuranics, technetium, and strontium. The cesium (Cs-137) and technetium (Tc-99) ion exchange removal is accomplished by using SuperLig 644, and 639 resins from IBC Advanced Technologies, American Fork, Utah. The resins were shown to selectively remove cesium and technetium (as anionic pertechnetate ) from alkaline salt solutions. The efficiency of ion exchange column loading and elution is a complex function involving feed compositions, equilibrium and kinetic behavior of ion exchange resins, diffusion, and the ionic strength and pH of the aqueous solution. A previous experimental program completed at the Savannah River Tech nology Center2 demonstrated the conceptualized flow sheet parameters with an Envelope C sample from Hanford Tank 241-AN-107. Those experiments also included determination of Cs and Tc batch distribution coefficients by SuperLig 644 and 639 resins and demonstration of small-scale column breakthrough and elution. The experimental findings were used in support of preliminary design bases and pretreatment flow sheet development by BNFL, Inc.

  7. Novel kinetic model of the removal of divalent heavy metal ions from aqueous solutions by natural clinoptilolite.

    PubMed

    Jovanovic, Mina; Rajic, Nevenka; Obradovic, Bojana

    2012-09-30

    Removal of heavy metal ions from aqueous solutions using zeolites is widely described by pseudo-second order kinetics although this model may not be valid under all conditions. In this work, we have extended approaches used for derivation of this model in order to develop a novel kinetic model that is related to the ion exchange mechanism underlying sorption of metal ions in zeolites. The novel model assumed two reversible steps, i.e. release of sodium ions from the zeolite lattice followed by bonding of the metal ion. The model was applied to experimental results of Cu(II) sorption by natural clinoptilolite-rich zeolitic tuff at different initial concentrations and temperatures and then validated by predictions of ion exchange kinetics of other divalent heavy metal ions (i.e. Mn(II), Zn(II) and Pb(II)). Model predictions were in excellent agreements with experimental data for all investigated systems. In regard to the proposed mechanism, modeling results implied that the sodium ion release rate was constant for all investigated metals while the overall rate was mainly determined by the rate of heavy metal ion bonding to the lattice. In addition, prediction capabilities of the novel model were demonstrated requiring one experimentally determined parameter, only. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Evaluation of electrochemical ion exchange for cesium elution

    SciTech Connect

    Bontha, J.D.; Kurath, D.E.; Surma, J.E.; Buehler, M.F.

    1996-04-01

    Electrochemical elution was investigated as an alternative method to acid elution for the desorption of cesium from loaded ion exchange resins. The approach was found to have several potential advantages over existing technologies, in particular, electrochemical elution eliminates the need for addition of chemicals to elute cesium from the ion exchange resin. Also, since, in the electrochemical elution process the eluting solution is not in direct contact with the ion exchange material, very small volumes of the eluting solution can be used in a complete recycle mode in order to minimize the total volume of the cesium elute. In addition, the cesium is eluted as an alkaline solution that does not require neutralization with caustic to meet the tank farm specifications. Other advantages include easy incorporation of the electrochemical elution process into the present cesium recovery schemes.

  9. Development and evaluation of ion exchange hollow fibers. [vinyl copolymers

    NASA Technical Reports Server (NTRS)

    Smith, J. K.

    1975-01-01

    An ion exchange hollow fiber impregnated with a vinylpyridine base was developed. The basic exchange resin used to impart the necessary permselectivity to the hollow fiber is a copolymer of vinylpyridine and dibromoethane prepared according to Rembaum. A slight pressure was used to impregnate the exchange monomer mixture into the void structure of the fiber wall, and with maintenance of subambient temperatures, the rate of cross-linking is slow enough to allow the growing polymer to permeate the wall structure before significant increase in polymer molecular weight. These ion exchange fibers are produced from polyacrylonitrile hollow fibers with an appropriate wall structure that enables the impregnating vinylpyridine monomer mixture to form a truly semipermeable anion barrier after curing.

  10. ION EXCHANGE IN FUSED SALTS. IV. DISTRIBUTION OF SELECTED TRANSITION ELEMENTS IN THE CHABAZITE-MOLTEN NANO3 SYSTEM,

    DTIC Science & Technology

    MINERALS, ION EXCHANGE, ION EXCHANGE, FUEL CELLS, LANTHANUM, DECOMPOSITION, EUROPIUM, IONS, EQUILIBRIUM(PHYSIOLOGY), NITRATES, COBALT, DISTRIBUTION, CERIUM, SILICATES, TRANSITION METALS, MOLTEN SALT NUCLEAR REACTORS.

  11. Catalysis using hydrous metal oxide ion exchangers

    DOEpatents

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  12. Recovery of boric acid from ion exchangers

    DOEpatents

    Pollock, Charles W.

    1976-01-01

    The recovery of boric acid from an anion exchange resin is improved by eluting the boric acid with an aqueous solution of ammonium bicarbonate. The boric acid can be readily purified and concentrated by distilling off the water and ammonium bicarbonate. This process is especially useful for the recovery of boric acid containing a high percentage of .sup.10 B which may be found in some nuclear reactor coolant solutions.

  13. Catalysis using hydrous metal oxide ion exchanges

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  14. Charge-exchange plasma generated by an ion thruster

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.

    1977-01-01

    The charge exchange plasma generated by an ion thruster was investigated experimentally using both 5 cm and 15 cm thrusters. Results are shown for wide ranges of radial distance from the thruster and angle from the beam direction. Considerations of test environment, as well as distance from the thruster, indicate that a valid simulation of a thruster on a spacecraft was obtained. A calculation procedure and a sample calculation of charge exchange plasma density and saturation electron current density are included.

  15. Unified superresolution experiments and stochastic theory provide mechanistic insight into protein ion-exchange adsorptive separations

    PubMed Central

    Kisley, Lydia; Chen, Jixin; Mansur, Andrea P.; Shuang, Bo; Kourentzi, Katerina; Poongavanam, Mohan-Vivekanandan; Chen, Wen-Hsiang; Dhamane, Sagar; Willson, Richard C.; Landes, Christy F.

    2014-01-01

    Chromatographic protein separations, immunoassays, and biosensing all typically involve the adsorption of proteins to surfaces decorated with charged, hydrophobic, or affinity ligands. Despite increasingly widespread use throughout the pharmaceutical industry, mechanistic detail about the interactions of proteins with individual chromatographic adsorbent sites is available only via inference from ensemble measurements such as binding isotherms, calorimetry, and chromatography. In this work, we present the direct superresolution mapping and kinetic characterization of functional sites on ion-exchange ligands based on agarose, a support matrix routinely used in protein chromatography. By quantifying the interactions of single proteins with individual charged ligands, we demonstrate that clusters of charges are necessary to create detectable adsorption sites and that even chemically identical ligands create adsorption sites of varying kinetic properties that depend on steric availability at the interface. Additionally, we relate experimental results to the stochastic theory of chromatography. Simulated elution profiles calculated from the molecular-scale data suggest that, if it were possible to engineer uniform optimal interactions into ion-exchange systems, separation efficiencies could be improved by as much as a factor of five by deliberately exploiting clustered interactions that currently dominate the ion-exchange process only accidentally. PMID:24459184

  16. Unified superresolution experiments and stochastic theory provide mechanistic insight into protein ion-exchange adsorptive separations.

    PubMed

    Kisley, Lydia; Chen, Jixin; Mansur, Andrea P; Shuang, Bo; Kourentzi, Katerina; Poongavanam, Mohan-Vivekanandan; Chen, Wen-Hsiang; Dhamane, Sagar; Willson, Richard C; Landes, Christy F

    2014-02-11

    Chromatographic protein separations, immunoassays, and biosensing all typically involve the adsorption of proteins to surfaces decorated with charged, hydrophobic, or affinity ligands. Despite increasingly widespread use throughout the pharmaceutical industry, mechanistic detail about the interactions of proteins with individual chromatographic adsorbent sites is available only via inference from ensemble measurements such as binding isotherms, calorimetry, and chromatography. In this work, we present the direct superresolution mapping and kinetic characterization of functional sites on ion-exchange ligands based on agarose, a support matrix routinely used in protein chromatography. By quantifying the interactions of single proteins with individual charged ligands, we demonstrate that clusters of charges are necessary to create detectable adsorption sites and that even chemically identical ligands create adsorption sites of varying kinetic properties that depend on steric availability at the interface. Additionally, we relate experimental results to the stochastic theory of chromatography. Simulated elution profiles calculated from the molecular-scale data suggest that, if it were possible to engineer uniform optimal interactions into ion-exchange systems, separation efficiencies could be improved by as much as a factor of five by deliberately exploiting clustered interactions that currently dominate the ion-exchange process only accidentally.

  17. Lability of heavy metal species in aquatic humic substances characterized by ion exchange with cellulose phosphate.

    PubMed

    Rocha, J C; Toscano, I A; Burba, P

    1997-01-01

    Labile metal species in aquatic humic substances (HSs) were characterized by ion exchange on cellulose phosphate (CellPhos) by applying an optimized batch procedure. The HSs investigated were pre-extracted from humic-rich waters by ultrafiltration and a resin XAD 8 procedure. The HS-metal species studied were formed by complexation with Cd(II), Ni(II), Cu(II), Mn(II) and Pb(II) as a function of time and the ratio ions to HSs. The kinetics and reaction order of this exchange process were studied. At the beginning (<3 min), the labile metal fractions are separated relatively quickly. After 3 min, the separation of the metal ions proceeds with uniform half-lives of about 12-14 min, revealing rather slow first-order kinetics. The metal exchange between HSs and CellPhos exhibited the following order of metal lability with the studied HSs: Cu > Pb > Mn > Ni > Cd. The required metal determinations were carried out by atomic absorption spectrometry.

  18. Rupture loop annex ion exchange RLAIX vault deactivation

    SciTech Connect

    Ham, J.E.; Harris, D.L., Westinghouse Hanford

    1996-08-01

    This engineering report documents the deactivation, stabilization and final conditions of the Rupture Loop Annex Ion Exchange (RLAIX) Vault located northwest of the 309 Building`s Plutonium Recycle Test Reactor (PRTR). Twelve ion exchange columns, piping debris, and column liquid were removed from the vault, packaged and shipped for disposal. The vault walls and floor were decontaminated, and portions of the vault were painted to fix loose contamination. Process piping and drains were plugged, and the cover blocks and rain cover were installed. Upon closure,the vault was empty, stabilized, isolated.

  19. Bench-Scale Studies with Argentine Ion Exchange Material

    SciTech Connect

    Cicero-Herman, C.A.

    2002-06-28

    The United States Department of Energy (DOE), as well as international atomic energy commission, facilities use ion exchange materials for purification of aqueous streams in the nuclear industry. Unfortunately, the use of the ion exchange materials creates a waste stream that can be very high in both organic and radioactive constituents. Therefore, disposal of the spent resins often becomes an economic problem because of the large volumes of resin produced and the relatively few technologies that are capable of economically stabilizing this waste. Vitrification of this waste stream presents a reasonable disposable alternative because of its inherent destruction capabilities, the volume reductions obtainable, and the durable product that it produces.

  20. Ion exchange with natural zeolites: an alternative for water softening?

    PubMed

    Cinar, S; Beler-Baykal, B

    2005-01-01

    Possibility of using natural zeolites for water softening was investigated. Quantitative data regarding separation of calcium from water at various levels of hardness through ion exchange with the ammonium selective natural zeolite clinoptilolite is reported. Capacity of the zeolite towards calcium removal in the presence of ammonium at low concentrations and calcium at higher concentrations, and breakthrough characteristics are presented. The results have revealed that removal of calcium, and hence hardness, through ion exchange with clinoptilolite under those circumstances is a promising alternative, with surface capacities reaching 11 mg calcium/g clinoptilolite.

  1. Recovery of uranium from phosphoric acid solutions using chelating ion-exchange resins

    SciTech Connect

    Kabay, N.; Demircioglu, M.; Yayh, S.; Guenay, E.; Yueksel, M.; Saglam, M.; Streat, M.

    1998-05-01

    In fertilizer manufacture, calcium phosphate in phosphate rock is rendered soluble by sulfuric acid attack. The phosphoric acid obtained in this way usually contains 26%--28% P{sub 2}O{sub 5}. Several novel processes have been developed for the recovery of uranium from wet-process phosphoric acid. Experimental measurements have been made on the batch extraction of uranium from phosphoric acid solutions using various chelating ion-exchange resins (RSPO, Diaion-CRP200, Diphonix, Purolite S940, Duolite ES467, and Lewatit OC 1060) and a solvent containing ion-exchange resins (Actinide-CU). The kinetic performance of ion-exchange resins was compared, and the effect of Fe(II) and Ca(II) ions on the sorption and elution performance has also been examined. The results showed that the resin Actinide-CU containing a diphosphonate extractant was very effective for removing uranium from phosphoric acid solution. However, the elution performance of this resin with both acid and carbonate eluants was poor. It is concluded that the chelating resins Diphonix, Duolite ES467, Lewatit OC 1060, and Purolite S940 give reasonable sorption of uranium in the presence of Fe(II) ions in batch sorption trials. The desorption of uranium has been performed quantitatively using carbonate eluants. Purolite S940 was used in small-scale column extractions of uranium from phosphoric acid solutions, and promising loading/elution profiles were obtained.

  2. The cleft ion fountain - A two-dimensional kinetic model

    NASA Technical Reports Server (NTRS)

    Horwitz, J. L.; Lockwood, M.

    1985-01-01

    The transport of ionospheric ions from a source in the polar cleft ionosphere through the polar magnetosphere is investigated using a two-dimensional, kinetic, trajectory-based code. The transport model includes the effects of gravitation, longitudinal magnetic gradient force, convection electric fields, and parallel electric fields. Individual ion trajectories as well as distribution functions and resulting bulk parameters of density, parallel average energy, and parallel flux for a presumed cleft ionosphere source distribution are presented for various conditions to illustrate parametrically the dependences on source energies, convection electric field strengths, ion masses, and parallel electric field strengths. The essential features of the model are consistent with the concept of a cleft-based ion fountain supplying ionospheric ions to the polar magnetosphere, and the resulting plasma distributions and parameters are in general agreement with recent low-energy ion measurements from the DE 1 satellite.

  3. Waste separation and pretreatment using crystalline silicotitanate ion exchangers

    SciTech Connect

    Tadros, M.E.; Miller, J.E.; Anthony, R.G.

    1997-10-01

    A new class of inorganic ion exchangers called crystalline silicotitanates (CSTs) has been developed jointly by Sandia National Laboratories and Texas A&M University to selectively remove Cs and other radionuclides from a wide spectrum of radioactive defense wastes. The CST exhibits high selectivity and affinity for Cs and Sr under a wide range of conditions. Tests show it can remove part-per-million concentrations of Cs{sup +} from highly alkaline, high-sodium simulated radioactive waste solutions modeled after those at Hanford, Oak Ridge, and Savannah River. The materials exhibit ion exchange properties based on ionic size selectivity. Specifically, crystalline lattice spacing is controlled to be highly selective for Cs ions even in waste streams containing very high (5 to 10 M) concentrations of sodium. The CST technology is being demonstrated with actual waste at several DOE facilities. The use of inorganic ion exchangers. The inorganics are more resistant to chemical, thermal, and radiation degradation. Their high selectivities result in more efficient operations offering the possibility of a simple single-pass operation. In contrast, regenerable organic ion exchangers require additional processing equipment to handle the regeneration liquids and the eluant with the dissolved Cs.

  4. Ion Dynamics during Substorm Events Modeled with Coupled Global MHD and Kinetic Models

    NASA Astrophysics Data System (ADS)

    Lapenta, G.; Ashour-Abdalla, M.; Walker, R. J.; El-Alaoui, M.

    2014-12-01

    We have studied ion dynamics during a substorm by using a coupled fluid-kinetic approach. The UCLA global magnetospheric model was applied first and its results in a region encompassing a magnetotail reconnection site and earthward propagating dipolarization fronts was selected as input state for a full kinetic simulation based on the iPic3D code [1]. The coupling is one-way: the MHD result is used to create a full kinetic initial state by using the approach described by [2] and to force the boundary conditions. The kinetic results are not fed back into the MHD run. This approach previously has been shown [3] to provide correctly the large scale picture for a kinetic approach when the duration of the kinetic run is not so long as to alter significantly the macroscopic state captured by MHD. Here we focus especially on the ions. The electrons were described in [3]. Three aspects are analyzed. First, the ions are accelerated during the event and we track the localization of the energy exchanged, separating the contributions to the directed energy and those to the thermal energy. Second, we consider the ion motion to identify the regions where the finite Larmor radius effects violate the drift approximation and the frozen-in condition, thereby identifying the ion diffusion region. Our approach follows individual electrons and ions fully kinetically and no approximation is made in the particle orbit, so our code is equipped to study accurately the regions where the drift approximation is valid. Finally, we consider the ion distribution as a possible source of instabilities, focusing especially on temperature anisotropy instabilities and on the firehose instability. The novelty of the approach is this kinetic study is done for a specific substorm by using the global state of the magnetosphere as provided by a global MHD simulation. This differs sharply from previous approaches based on analytical approximations such as the Harris or the (quasi)-parabolic equilibria. [1

  5. Rapid preparation of biosorbents with high ion exchange capacity from rice straw and bagasse for removal of heavy metals.

    PubMed

    Rungrodnimitchai, Supitcha

    2014-01-01

    This work describes the preparation of the cellulose phosphate with high ion exchange capacity from rice straw and bagasse for removal of heavy metals. In this study, rice straw and bagasse were modified by the reaction with phosphoric acid in the presence of urea. The introduced phosphoric group is an ion exchangeable site for heavy metal ions. The reaction by microwave heating yielded modified rice straw and modified bagasse with greater ion exchange capacities (∼3.62 meq/g) and shorter reaction time (1.5-5.0 min) than the phosphorylation by oil bath heating. Adsorption experiments towards Pb²⁺, Cd²⁺, and Cr³⁺ ions of the modified rice straw and the modified bagasse were performed at room temperature (heavy metal concentration 40 ppm, adsorbent 2.0 g/L). The kinetics of adsorption agreed with the pseudo-second-order model. It was shown that the modified rice straw and the modified bagasse could adsorb heavy metal ions faster than the commercial ion exchange resin (Dowax). As a result of Pb²⁺ sorption test, the modified rice straw (RH-NaOH 450W) removed Pb²⁺ much faster in the initial step and reached 92% removal after 20 min, while Dowax (commercial ion exchange resin) took 90 min for the same removal efficiency.

  6. Rapid Preparation of Biosorbents with High Ion Exchange Capacity from Rice Straw and Bagasse for Removal of Heavy Metals

    PubMed Central

    2014-01-01

    This work describes the preparation of the cellulose phosphate with high ion exchange capacity from rice straw and bagasse for removal of heavy metals. In this study, rice straw and bagasse were modified by the reaction with phosphoric acid in the presence of urea. The introduced phosphoric group is an ion exchangeable site for heavy metal ions. The reaction by microwave heating yielded modified rice straw and modified bagasse with greater ion exchange capacities (∼3.62 meq/g) and shorter reaction time (1.5–5.0 min) than the phosphorylation by oil bath heating. Adsorption experiments towards Pb2+, Cd2+, and Cr3+ ions of the modified rice straw and the modified bagasse were performed at room temperature (heavy metal concentration 40 ppm, adsorbent 2.0 g/L). The kinetics of adsorption agreed with the pseudo-second-order model. It was shown that the modified rice straw and the modified bagasse could adsorb heavy metal ions faster than the commercial ion exchange resin (Dowax). As a result of Pb2+ sorption test, the modified rice straw (RH-NaOH 450W) removed Pb2+ much faster in the initial step and reached 92% removal after 20 min, while Dowax (commercial ion exchange resin) took 90 min for the same removal efficiency. PMID:24578651

  7. Ion exchange chromatography of proteins and clearance of aggregates.

    PubMed

    Yigzaw, Y; Hinckley, P; Hewig, A; Vedantham, G

    2009-06-01

    Clearance of product related aggregates in therapeutic proteins is a major focus of purification process development. A typical purification process will have one or two chromatographic steps that remove these product related aggregates to an acceptable level. Both cation exchange and anion exchange chromatography can provide robust clearance of aggregates. The primary factors that are critical for aggregate clearance are: resin chemistry, binding and elution condition, peak collection and column load factor. This review covers how these factors can be optimized to increase the effectiveness of ion exchange chromatography in removing aggregates.

  8. Insoluble polyelectrolyte and ion-exchange hollow fiber impregnated therewith

    NASA Technical Reports Server (NTRS)

    Rembaum, A. (Inventor)

    1977-01-01

    The number of quaternary sites and ion exchange capacity of a polyquaternary, cross linked, insoluble copolymer of a vinyl pyridine and a dihalo organic compound is increased by about 15-35% by reaction of the polymer with an amine followed by quaternization, if required. The polymer forms spontaneously in the presence of a substrate such as within the pores of a hollow fiber. The improved resin impregnated fiber may be utilized to remove ions from waste or process steams.

  9. Kinetic treatment of nonlinear ion-acoustic waves in multi-ion plasma

    NASA Astrophysics Data System (ADS)

    Ahmad, Zulfiqar; Ahmad, Mushtaq; Qamar, A.

    2017-09-01

    By applying the kinetic theory of the Valsove-Poisson model and the reductive perturbation technique, a Korteweg-de Vries (KdV) equation is derived for small but finite amplitude ion acoustic waves in multi-ion plasma composed of positive and negative ions along with the fraction of electrons. A correspondent equation is also derived from the basic set of fluid equations of adiabatic ions and isothermal electrons. Both kinetic and fluid KdV equations are stationary solved with different nature of coefficients. Their differences are discussed both analytically and numerically. The criteria of the fluid approach as a limiting case of kinetic theory are also discussed. The presence of negative ion makes some modification in the solitary structure that has also been discussed with its implication at the laboratory level.

  10. Microspheres aided introduction of ionophore and ion-exchanger to the ion-selective membrane.

    PubMed

    Wojciechowski, Marcin; Kisiel, Anna; Bulska, Ewa; Michalska, Agata

    2012-01-15

    In this work a novel method for introduction of ionophore and ion-exchanger to the ion-selective polyacrylate based membrane is proposed. These compounds (and optionally primary ions) are introduced to polyacrylate microspheres, used to prepare ion-selective membrane. The approach proposed here can be used to prepare membranes containing primary ions equally distributed through the receptor phase, i.e. membranes that do not require conditioning in primary ions solution and are free from problems related to slow diffusion of primary ions. Thus obtained sensors were characterized with linear responses (also at relatively high activities) and high selectivities, despite considerable reduction of ionophore and ion-exchanger amount introduced to the membrane. To be able to prepare ion-selective membranes using this approach, a method for quantification of ionophore and ion-exchanger introduced into microspheres is required. In this work a novel method utilizing high performance liquid chromatography (HPLC) with DAD or FLD detection is proposed. Incorporation of ionophore and ion-exchanger into the microspheres was achieved either by absorption into ready spheres or in course of photopolymerization of polymeric beads. The obtained results have proven that both procedures led to incorporation of ionophore/ion-exchanger into polymeric spheres, however, the content of the compounds in the spheres post process is different from their ratio in solution from which they had been introduced. These effects need to be considered/compensated while preparing microspheres containing ion-selective membranes. As a model system poly(n-butyl acrylate) spheres, silver selective ionophore and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate were chosen, resulting ultimately in silver-selective electrodes. Copyright © 2011 Elsevier B.V. All rights reserved.

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

    PubMed

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

    2014-10-21

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

  12. New Metal Niobate and Silicotitanate Ion Exchangers: Development and Characterization

    SciTech Connect

    Alexandra Navrotsky; Mary Lou Balmer; Tina M. Nenoff; Yali Su

    2003-12-05

    This renewal proposal outlines our current progress and future research plans for ion exchangers: novel metal niobate and silicotitanate ion exchangers and their ultimate deployment in the DOE complex. In our original study several forms (including Cs exchanged) of the heat treated Crystalline Silicotitanates (CSTs) were fully characterized by a combination of high temperature synthesis and phase identification, low temperature synthesis and phase identification, and thermodynamics. This renewal proposal is predicated on work completed in our current EMSP program: we have shown preliminary data of a novel class of niobate-based molecular sieves (Na/Nb/M/O, M = transition metals), which show exceptionally high selectivity for divalent cations under extreme conditions (acid solutions, competing cations), in addition to novel silicotitanate phases which are also selective for divalent cations. Furthermore, these materials are easily converted by a high temperature in-situ heat treatment into a refractory ceramic waste form with low cation leachability. The new waste form is a perovskite phase, which is also a major component of Synroc, a titanate ceramic waste form used for sequestration of HLW wastes from reprocessed, spent nuclear fuel. These new niobate ion exchangers also shown orders of magnitude better selectivity for Sr2+ under acid conditions than any other material. The goal of the program is to reduce the costs associated with divalent cation waste removal and disposal, to minimize the risk of contamination to the environment during ion exchanger processing, and to provide DOE with materials for near-term lab-bench stimulant testing, and eventual deployment. The proposed work will provide information on the structure/property relationship between ion exchanger frameworks and selectivity for specific ions, allowing for the eventual ''tuning'' of framework for specific ion exchange needs. To date, DOE sites have become interested in on-site testing of these

  13. Concentration profiles in heterogeneous ion-exchange membranes

    SciTech Connect

    Smirnova, N.M.; Glazkova, I.N.; Glukhova, L.P.; Murzinov, V.I.; Komarova, N.I.; Kvaratskheli, Yu.K.

    1982-05-10

    Concentration profiles of uranium and SO/sub 4//sup -2/ ions were determined in MKK-1 (based on KU-2 cation-exchange resin) and MAK-2 (based on AM anion-exchange resin) heterogeneous membranes in the course of diffusion and electrodialysis. The method employed for locating the position and determining the concentration of ions in a particular region of an ion-exchange material was local x-ray spectrochemical analysis with the aid of an electron probe. A solution containing 10g of U per liter and 0.5 N/sub 2/SO/sub 4/ was used as the ''transferring'' solution. Uranium is present in this solution in the form of UO/sub 2//sup 2 +/ cations and (UO/sub 2/(SO/sub 4/)/sub 2/)/sup 2 -/ and (UO/sub 2/(SO/sub 4/)/sub 3/)/sup 4 -/ anionic complexes, so that it is transported both through the cation-exchange and the anion-exchange membranes. The ''receiving'' solution was 0.1N H/sub 2/SO/sub 4/. The REMP-2 electron probe microanalyzer was used for recording the concentration profiles. The uranium L..cap alpha../sub 1/ line (lambda = 9.1 x 10/sup -11/m) and the sulfur K..cap alpha../sub 1,2/ line (lambda = 53.7 x 10/sup -11/m) were used as the analytical lines. The membrane conductivities, and the amount of uranium sorbed were determined at the same time. This investigation confirmed that the method of local x-ray spectrochemical analysis in conjunction with physicochemical investigations of the properties of ion-exchange membranes is a promising, reliable, and rapid method for studying the mechanism of ion transport in comparison with the use of multiplet devices. It can make mathematical modelling of transport processes considerably easier and more precise, as introduction of various assumptions is obviated.

  14. Scrape-off layer modeling with kinetic or diffusion description of charge-exchange atoms

    NASA Astrophysics Data System (ADS)

    Tokar, M. Z.

    2016-12-01

    Hydrogen isotope atoms, generated by charge-exchange (c-x) of neutral particles recycling from the first wall of a fusion reactor, are described either kinetically or in a diffusion approximation. In a one-dimensional (1-D) geometry, kinetic calculations are accelerated enormously by applying an approximate pass method for the assessment of integrals in the velocity space. This permits to perform an exhaustive comparison of calculations done with both approaches. The diffusion approximation is deduced directly from the velocity distribution function of c-x atoms in the limit of charge-exchanges with ions occurring much more frequently than ionization by electrons. The profiles across the flux surfaces of the plasma parameters averaged along the main part of the scrape-off layer (SOL), beyond the X-point and divertor regions, are calculated from the one-dimensional equations where parallel flows of charged particles and energy towards the divertor are taken into account as additional loss terms. It is demonstrated that the heat losses can be firmly estimated from the SOL averaged parameters only; for the particle loss the conditions in the divertor are of importance and the sensitivity of the results to the so-called "divertor impact factor" is investigated. The coupled 1-D models for neutral and charged species, with c-x atoms described either kinetically or in the diffusion approximation, are applied to assess the SOL conditions in a fusion reactor, with the input parameters from the European DEMO project. It is shown that the diffusion approximation provides practically the same profiles across the flux surfaces for the plasma density, electron, and ion temperatures, as those obtained with the kinetic description for c-x atoms. The main difference between the two approaches is observed in the characteristics of these species themselves. In particular, their energy flux onto the wall is underestimated in calculations with the diffusion approximation by 20 % - 30

  15. Improved reliability of leucite reinforced glass by ion exchange.

    PubMed

    Fischer, H; Maier, H R; Marx, R

    2000-03-01

    The aim of this study was to develop an adequate process-, proof- and calculation technique for the chemical strengthening of dental ceramic materials in order to evaluate the efficiency of this method from the engineering point of view. Ion exchange examinations below glass temperature have been done for the dental all ceramic system IPS-Empress (Ivoclar). In addition experiments on specimens were undertaken, which were stored in artificial saliva for the period of one month after the ion exchange treatment. The efficiency of the ion-exchange treatments has been evaluated based on the chemical composition of the surface layer, the residual stress distribution, the flexural- and the burst-strength and surface hardness. In addition, Weibull statistical analysis of the four-point bending and burst test data provides new information about the failure mechanisms of chemically strengthened dental ceramics. The ion-exchange process with a potassium salt increases the reliability of the dental ceramic material "IPS-Empress". By the KNO3 or Tuf-Coat ion exchange treatment potassium ions will be implanted as clusters directly into the crystal lattice which results in an increase of the binding energy and hence, in a pronounced increase in the surface hardness. In particular the stress bearing capabilities of dental all ceramic restorations, which are subject to high bending stresses, i.e. dental crowns and dental bridges, are largely improved by the induced residual stresses. This increase of residual stresses did not relax significantly after a one month storage in artificial saliva. Enhanced load limits and a more narrow strength distribution spectrum is considered desirable for increasing the clinical longevity of all ceramics.

  16. Electrically switched cesium ion exchange. FY 1997 annual report

    SciTech Connect

    Lilga, M.A.; Orth, R.J.; Sukamto, J.P.H.

    1997-09-01

    This paper describes the Electrically Switched Ion Exchange (ESIX) separation technology being developed as an alternative to ion exchange for removing radionuclides from high-level waste. Progress in FY 1997 for specific applications of ESIX is also outlined. The ESIX technology, which combines ion exchange and electrochemistry, is geared toward producing electroactive films that are highly selective, regenerable, and long lasting. During the process, ion uptake and elution can be controlled directly by modulating the potential of an ion exchange film that has been electrochemically deposited onto a high surface area electrode. This method adds little sodium to the waste stream and minimizes the secondary wastes associated with traditional ion exchange techniques. Development of the ESIX process is well underway for cesium removal using ferrocyanides as the electroactive films. Films having selectivity for perrhenate (a pertechnetate surrogate) over nitrate also have been deposited and tested. Based on the ferrocyanide film capacity, stability, rate of uptake, and selectivity shown during performance testing, it appears possible to retain a consistent rate of removal and elute cesium into the same elution solution over several load/unload cycles. In batch experiments, metal hexacyanoferrate films showed high selectivities for cesium in concentrated sodium solutions. Cesium uptake was unaffected by Na/Cs molar ratios of up to 2 x 10{sup 4} , and reached equilibrium within 18 hours. During engineering design tests using 60 pores per inch, high surface area nickel electrodes, nickel ferrocyanide films displayed continued durability. losing less than 20% of their capacity after 1500 load/unload cycles. Bench-scale flow system studies showed no change in capacity or performance of the ESIX films at a flow rate up to 13 BV/h, the maximum flow rate tested, and breakthrough curves further supported once-through waste processing. 9 refs., 24 figs.

  17. RNA folding: structure prediction, folding kinetics and ion electrostatics.

    PubMed

    Tan, Zhijie; Zhang, Wenbing; Shi, Yazhou; Wang, Fenghua

    2015-01-01

    Beyond the "traditional" functions such as gene storage, transport and protein synthesis, recent discoveries reveal that RNAs have important "new" biological functions including the RNA silence and gene regulation of riboswitch. Such functions of noncoding RNAs are strongly coupled to the RNA structures and proper structure change, which naturally leads to the RNA folding problem including structure prediction and folding kinetics. Due to the polyanionic nature of RNAs, RNA folding structure, stability and kinetics are strongly coupled to the ion condition of solution. The main focus of this chapter is to review the recent progress in the three major aspects in RNA folding problem: structure prediction, folding kinetics and ion electrostatics. This chapter will introduce both the recent experimental and theoretical progress, while emphasize the theoretical modelling on the three aspects in RNA folding.

  18. Charge Exchange with Highly Charged Ions

    NASA Astrophysics Data System (ADS)

    Glick, Jeremy; Ferri, Kevin; Schmitt, Jaclyn; Hanson, Joshua; Marler, Joan

    2016-05-01

    A detailed study of the physics of highly charged ions (HCIs) is critical for a deep understanding of observed phenomena resulting from interactions of HCIs with neutral atoms in astrophysical and fusion environments. Specifically the charge transfer rates and spectroscopy of the subsequent decay fluorescence are of great interest to these communities. Results from a laboratory based investigation of these rates will be presented. The experiment takes advantage of an energy and charge state selected beam of HCIs from the recently on-line Clemson University EBIT (CUEBIT). Progress towards an experimental apparatus for retrapping HCIs towards precision spectroscopy of HCIs will also be presented.

  19. ATPases, ion exchangers and human sperm motility.

    PubMed

    Peralta-Arias, Rubén D; Vívenes, Carmen Y; Camejo, María I; Piñero, Sandy; Proverbio, Teresa; Martínez, Elizabeth; Marín, Reinaldo; Proverbio, Fulgencio

    2015-05-01

    Human sperm has several mechanisms to control its ionic milieu, such as the Na,K-ATPase (NKA), the Ca-ATPase of the plasma membrane (PMCA), the Na(+)/Ca(2) (+)-exchanger (NCX) and the Na(+)/H(+)-exchanger (NHE). On the other hand, the dynein-ATPase is the intracellular motor for sperm motility. In this work, we evaluated NKA, PMCA, NHE, NCX and dynein-ATPase activities in human sperm and investigated their correlation with sperm motility. Sperm motility was measured by Computer Assisted Semen Analysis. It was found that the NKA activity is inhibited by ouabain with two Ki (7.9 × 10(-9) and 9.8 × 10(-5) M), which is consistent with the presence of two isoforms of α subunit of the NKA in the sperm plasma membranes (α1 and α4), being α4 more sensitive to ouabain. The decrease in NKA activity is associated with a reduction in sperm motility. In addition, sperm motility was evaluated in the presence of known inhibitors of NHE, PMCA and NCX, such as amiloride, eosin, and KB-R7943, respectively, as well as in the presence of nigericin after incubation with ouabain. Amiloride, eosin and KB-R7943 significantly reduced sperm motility. Nigericin reversed the effect of ouabain and amiloride on sperm motility. Dynein-ATPase activity was inhibited by acidic pH and micromolar concentrations of Ca(2) (+). We explain our results in terms of inhibition of the dynein-ATPase in the presence of higher cytosolic H(+) and Ca(2) (+), and therefore inhibition of sperm motility. © 2015 Society for Reproduction and Fertility.

  20. Charge-exchange born He(+) ions in the solar wind

    NASA Technical Reports Server (NTRS)

    Gruntman, Michael A.

    1992-01-01

    The effect of charge transfer between solar wind alpha-particles and hydrogen atoms of interstellar origin is revisited. Singly-charged helium ions born in the charge transfer carry important information on processes in the solar wind and the heliosphere. The velocity distribution of such He(+) ions is substantially different from that of He(+) pick-up ions due to ionization of the interstellar helium atoms. Estimates of the expected abundances of the charge-exchange born He(+) in the solar wind are presented, and the possibility of measuring this plasma component on deep space missions is discussed.

  1. Kinetic analysis of an anion exchange absorbent for CO2 capture from ambient air

    PubMed Central

    Shi, Xiaoyang; Li, Qibin; Lackner, Klaus S.

    2017-01-01

    This study reports a preparation method of a new moisture swing sorbent for CO2 capture from air. The new sorbent components include ion exchange resin (IER) and polyvinyl chloride (PVC) as a binder. The IER can absorb CO2 when surrounding is dry and release CO2 when surrounding is wet. The manuscript presents the studies of membrane structure, kinetic model of absorption process, performance of desorption process and the diffusivity of water molecules in the CO2 absorbent. It has been proved that the kinetic performance of CO2 absorption/desorption can be improved by using thin binder and hot water treatment. The fast kinetics of P-100-90C absorbent is due to the thin PVC binder, and high diffusion rate of H2O molecules in the sample. The impressive is this new CO2 absorbent has the fastest CO2 absorption rate among all absorbents which have been reported by other up-to-date literatures. PMID:28640914

  2. Thermal Analysis for Ion-Exchange Column System

    SciTech Connect

    Lee, Si Y.; King, William D.

    2012-12-20

    Models have been developed to simulate the thermal characteristics of crystalline silicotitanate ion exchange media fully loaded with radioactive cesium either in a column configuration or distributed within a waste storage tank. This work was conducted to support the design and operation of a waste treatment process focused on treating dissolved, high-sodium salt waste solutions for the removal of specific radionuclides. The ion exchange column will be installed inside a high level waste storage tank at the Savannah River Site. After cesium loading, the ion exchange media may be transferred to the waste tank floor for interim storage. Models were used to predict temperature profiles in these areas of the system where the cesium-loaded media is expected to lead to localized regions of elevated temperature due to radiolytic decay. Normal operating conditions and accident scenarios (including loss of solution flow, inadvertent drainage, and loss of active cooling) were evaluated for the ion exchange column using bounding conditions to establish the design safety basis. The modeling results demonstrate that the baseline design using one central and four outer cooling tubes provides a highly efficient cooling mechanism for reducing the maximum column temperature. In-tank modeling results revealed that an idealized hemispherical mound shape leads to the highest tank floor temperatures. In contrast, even large volumes of CST distributed in a flat layer with a cylindrical shape do not result in significant floor heating.

  3. Method and solvent composition for regenerating an ion exchange resin

    SciTech Connect

    Even, William R.; Irvin, David J.; Irvin, Jennifer A.; Tarver, Edward E.; Brown, Gilbert M.; Wang, James C. F.

    2002-01-01

    A method and composition for removing perchlorate from a highly selective ion exchange resin is disclosed. The disclosed approach comprises treating the resin in a solution of super critical or liquid carbon dioxide and one or more quaternary ammonium chloride surfactant compounds.

  4. EVALUATING ION EXCHANGE FOR REMOVING RADIUM FROM GROUNDWATER

    EPA Science Inventory

    This article, the second in a series, focuses on the results of bench- and pilot-scale studies of ion exchange processes for radium removal from groundwater in Lemont, Ill. Batch and column studies indicated a very high resin selectivity for radium compared with common cations. E...

  5. 21 CFR 173.25 - Ion-exchange resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...-methyl-amino-propyl-amine and quaternized with methyl chloride. (19) Epichlorohydrin cross-linked with ammonia and then quaternized with methyl chloride to contain not more than 18 percent strong base capacity..., sodium, and sulfate except that: The ion-exchange resin identified in paragraph (a)(12) of this section...

  6. Determination of boron in silicates after ion exchange separation

    USGS Publications Warehouse

    Kramer, H.

    1955-01-01

    Existing methods for the determination of boron in silicates are not entirely satisfactory. Separation as the methyl ester is lengthy and frequently erratic. An accurate and rapid method applicable to glass, mineral, ore, and water samples uses ion exchange to remove interfering cations, and boron is determined titrimetrically in the presence of mannitol, using a pH meter to indicate the end point.

  7. EVALUATING ION EXCHANGE FOR REMOVING RADIUM FROM GROUNDWATER

    EPA Science Inventory

    This article, the second in a series, focuses on the results of bench- and pilot-scale studies of ion exchange processes for radium removal from groundwater in Lemont, Ill. Batch and column studies indicated a very high resin selectivity for radium compared with common cations. E...

  8. Copper Removal from A-01 Outfall by Ion Exchange

    SciTech Connect

    Oji, L.N.

    1999-02-17

    Chelex100, a commercially available ion exchange resin, has been identified in this study as having a significant affinity for copper and zinc in the A-01 outfall water. Removal of copper and zinc from A-01 outfall water will ensure that the outfall meets the state of South Carolina's limit on these heavy metals.

  9. Cesium Ion Exchange Using Tank 241-AN-104 Supernate

    SciTech Connect

    Adu-Wusu, K.

    2003-12-22

    The River Protection Project is to design and build a high level nuclear waste treatment facility. The waste treatment plant is to process millions of gallons of radioactive waste stored in tanks at the Hanford Site. The high level nuclear waste treatment process includes various unit operations, such as ultrafiltration, precipitation, evaporation, ion exchange, and vitrification. Ion exchange is identified as the optimal treatment method for removal of cesium-137 and Tc-99 from the waste. Extensive ion exchange testing was performed using small-scale columns with actual waste samples. The objectives of this study were to: demonstrate SuperLig 644 ion exchange performance and process steps for the removal of cesium from actual AN-104 tank waste; pretreat actual AN-104 tank waste to reduce the concentration of cesium-137 in the waste below LAW vitrification limit; produce and characterize cesium eluate solutions for use in eluate evaporation tests. The experiments consisted of batch contact and small-scale column tests. The batch contact tests measured sorption partition coefficients Kds. The Kds were used to predict the effective resin capacity. The small-scale column tests, which closely mimic plant conditions, generated loading and elution profile data used to determine whether removal targets and design requirements were met.

  10. Ion-exchanged glass waveguide amplifiers and lasers

    NASA Astrophysics Data System (ADS)

    Kevorkian, Antoine P.

    1998-04-01

    Planar devices made by ion-exchange provide efficient active or active/passive functions. Compact amplifiers with 24 dB single pass gain for a single 980 nm laser diode pumping are presented, as well as 1535 nm lasers with 27% slope efficiency.

  11. Kinetics and thermodynamics studies of copper exchange on Na-montmorillonite clay mineral.

    PubMed

    El-Batouti, Mervette; Sadek, Olfat M; Assaad, Fayez F

    2003-03-15

    The kinetics of Cu ion exchange on Na-montmorillonite clay has been investigated at 20, 30, and 40 degrees C in water, methanol, and ethanol. The reaction is endothermic in nature. Solvent effects on the reaction rate have been discussed. The thermodynamic activation parameters were calculated and discussed in terms of solvation effects. A multiple reaction rate order equation was used to describe the adsorption process. Lower rates and higher activation energies (Ea) were observed in aqueous solution than in either of the alcohols. The Ea values ranged from 20.88 kJmol(-1) in water to 9.20 kJmol(-1) in ethanol, while at 20 degrees C the rate constant (k) varied from 0.111 ppm(-1)s(-1) in water to 0.205 ppm(-1)s(-1) in ethanol. The main factor influencing the rate of the adsorption process is the mobility of the adsorbed Cu cations, which is apparently larger in alcohols than in water, due to the difference in the molar activation energy of the solvent. The determined isokinetic temperature indicates that the reaction is enthalpy-controlled, where the interaction between solvent and clay surface plays an important role. A reaction mechanism that describes the solvent effect on the rate of Cu ion exchange is proposed.

  12. Fluid and kinetic models of negative ion sheaths

    SciTech Connect

    Cavenago, M.

    2011-09-26

    Due to the presence of a large transverse magnetic field (B{sub x} and B{sub y} where z is the extraction axis), the extraction of electrons from a negative ion source is likely to happen with a large angle with respect to z axis. The negative ion and electron sheaths are here studied both with kinetic and with fluid models. First, Vlasov-Poisson models are reduced to one dimensional integrodifferential equations, discussing also trapped orbits. The integrodifferential equations for electron transport are analytically solved for a variety of extraction potentials (in 1D). Collision frequency dependency from electron flow speed and temperature is discussed. Then both ion and electron space charge and fluid motion are solved, using electron densities expression consistent with kinetic model. Results for the sheath charge profile and extraction field as a function of B{sub x} are shown.

  13. Ion and velocity map imaging for surface dynamics and kinetics

    NASA Astrophysics Data System (ADS)

    Harding, Dan J.; Neugebohren, Jannis; Hahn, Hinrich; Auerbach, D. J.; Kitsopoulos, T. N.; Wodtke, Alec M.

    2017-07-01

    We describe a new instrument that uses ion imaging to study molecular beam-surface scattering and surface desorption kinetics, allowing independent determination of both residence times on the surface and scattering velocities of desorbing molecules. This instrument thus provides the capability to derive true kinetic traces, i.e., product flux versus residence time, and allows dramatically accelerated data acquisition compared to previous molecular beam kinetics methods. The experiment exploits non-resonant multiphoton ionization in the near-IR using a powerful 150-fs laser pulse, making detection more general than previous experiments using resonance enhanced multiphoton ionization. We demonstrate the capabilities of the new instrument by examining the desorption kinetics of CO on Pd(111) and Pt(111) and obtain both pre-exponential factors and activation energies of desorption. We also show that the new approach is compatible with velocity map imaging.

  14. Chromium removal from ground water by Ion exchange resins

    SciTech Connect

    Skiadas, P.

    1994-05-06

    The ground water at several monitoring wells at LLNL has been found to exceed the Surface Water Discharge Limits for Cr(VI). Ion exchange resins have been selected for its removal. A research study is underway to determine which commercial resin is preferred for LLNL`s ground water. The choice of an appropriate resin will be based on Cr(VI) exchange capacity, regeneration efficiency, and pH stabilization. A sequestering agent must also be selected to be used for the elimination of scaling at the treatment facilities. The chemistry of ion exchange resins, and instrumentation and procedures are explained and described in the following paper. Comparison of the different resins tested lead us to the selection of the most effective one to be used in the treatment facilities.

  15. Systematics of heavy-ion charge-exchange straggling

    NASA Astrophysics Data System (ADS)

    Sigmund, P.; Schinner, A.

    2016-10-01

    The dependence of heavy-ion charge-exchange straggling on the beam energy has been studied theoretically for several ion-target combinations. Our previous work addressed ions up to krypton, while the present study focuses on heavier ions, especially uranium. Particular attention has been paid to a multiple-peak structure which has been predicted theoretically in our previous work. For high-Z1 and high-Z2 systems, exemplified by U in Au, we identify three maxima in the energy dependence of charge-exchange straggling, while the overall magnitude is comparable with that of collisional straggling. Conversely, for U in C, charge-exchange straggling dominates, but only two peaks lie in the energy range where we presently are able to produce credible predictions. For U-Al we find good agreement with experiment in the energy range around the high-energy maximum. The position of the high-energy peak - which is related to processes in the projectile K shell - is found to scale as Z12, in contrast to the semi-empirical Z13/2 dependence proposed by Yang et al. Measurements for heavy ions in heavy targets are suggested in order to reconcile a major discrepancy between the present calculations and the frequently-used formula by Yang et al.

  16. Kinetic Simulations of Ion Beam Neutralization

    SciTech Connect

    Chang, O.; Wang, J.

    2011-05-20

    Full particle PIC simulations are performed to study the neutralization of an ion beam in the cohesionless, mesothermal regime. Simulations further confirmed that neutralization is achieved through interactions between the trapped electrons and the potential well established by the propagation of the beam front along the beam direction and is not through plasma instabilities as previous studies suggested. In the transverse direction, the process is similar to that of the expansion of mesothermal plasma into vacuum. Parametric simulations are also performed to investigate the effects of beam radius and domain boundary condition on the neutralization process. The results suggests that, while the qualitative behavior may be similar in ground tests, quantitative parameters such as the beam potential will be affected significantly by the vacuum chamber because of the limits imposed on the expansion process by the finite chamber space.

  17. Characterization of cross-linked cellulosic ion-exchange adsorbents: 2. Protein sorption and transport.

    PubMed

    Angelo, James M; Cvetkovic, Aleksandar; Gantier, Rene; Lenhoff, Abraham M

    2016-03-18

    Adsorption behavior in the HyperCel family of cellulosic ion-exchange materials (Pall Corporation) was characterized using methods to assess, quantitatively and qualitatively, the dynamics of protein uptake as well as static adsorption as a function of ionic strength and protein concentration using several model proteins. The three exchangers studied all presented relatively high adsorptive capacities under low ionic strength conditions, comparable to commercially available resins containing polymer functionalization aimed at increasing that particular characteristic. The strong cation- and anion-exchange moieties showed higher sensitivity to increasing salt concentrations, but protein affinity on the salt-tolerant STAR AX HyperCel exchanger remained strong at ionic strengths normally used in downstream processing to elute material fully during ion-exchange chromatography. Very high uptake rates were observed in both batch kinetics experiments and time-series confocal laser scanning microscopy, suggesting low intraparticle transport resistances relative to external film resistance, even at higher bulk protein concentrations where the opposite is typically observed. Electron microscopy imaging of protein adsorbed phases provided additional insight into particle structure that could not be resolved in previous work on the bare resins. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Characterization of Cross-Linked Cellulosic Ion-Exchange Adsorbents: 2. Protein Sorption and Transport

    PubMed Central

    Angelo, James M.; Cvetkovic, Aleksandar; Gantier, Rene; Lenhoff, Abraham M.

    2016-01-01

    Adsorption behavior in the HyperCel family of cellulosic ion-exchange materials (Pall Corporation) was characterized using methods to assess, quantitatively and qualitatively, the dynamics of protein uptake as well as static adsorption as a function of ionic strength and protein concentration using several model proteins. The three exchangers studied all presented relatively high adsorptive capacities under low ionic strength conditions, comparable to commercially available resins containing polymer functionalization aimed at increasing that particular characteristic. The strong cation- and anion-exchange moieties showed higher sensitivity to increasing salt concentrations, but protein affinity on the salt-tolerant STAR AX HyperCel exchanger remained strong at ionic strengths normally used in downstream processing to elute material fully during ion-exchange chromatography. Very high uptake rates were observed in both batch kinetics experiments and time-series confocal laser scanning microscopy, suggesting low intraparticle transport resistances relative to external film resistance, even at higher bulk protein concentrations where the opposite is typically observed. Electron microscopy imaging of protein adsorbed phases provided additional insight into particle structure that could not be resolved in previous work on the bare resins. PMID:26905881

  19. Modeling and analysis of ion-exchanged photonic devices

    NASA Astrophysics Data System (ADS)

    West, Brian Robert

    Photonic devices fabricated by ion exchange in glass have evolved to the point where conventional assumptions of waveguide symmetry and mutual independence are no longer valid. For example, during field-assisted ion exchange processes, the nonhomogeneity of ionic conductivity in the vicinity of the waveguide results in a time-dependent perturbation of the electric field. Previous studies have shown that the depth and vertical symmetry of buried waveguides are noticeably affected by the field perturbation. This Dissertation describes an advanced modeling tool for guided-wave devices based on ion-exchanged glass waveguides. A genetic algorithm is proposed to determine the physical parameters that drive the ion exchange process. The diffusion equation describing binary ion exchange is solved numerically. The effect of field perturbation, due not only to the conductivity profile, but also to the proximity of adjacent waveguides or partial masking during a field-assisted burial, is accounted for. A semivectorial finite difference method is then employed to determine the modal properties of the waveguide structures. The model is validated by comparison with a fabricated waveguide containing a Bragg grating. The modeled waveguides are utilized in the design of a multimode interference (MMI) device. A novel genetic algorithm-based design methodology is developed to circumvent issues with the commonly used self-imaging theory that arise when the MMI device operates in the regime of weak guiding. A combination of semivectorial finite difference modeling in two transverse dimensions and mode propagation analysis (MPA) in the propagation direction is used to evaluate the merit of each trial design. Two examples are provided of a 1 x 4 power splitter, which show considerable improvement in power imbalance and polarization dependent loss over that obtained by self-imaging theory.

  20. Graphene/Ionic Liquid Composite Films and Ion Exchange

    PubMed Central

    Mo, Yufei; Wan, Yunfang; Chau, Alicia; Huang, Fuchuan

    2014-01-01

    Wettability of graphene is adjusted by the formation of various ionic surfaces combining ionic liquid (IL) self-assembly with ion exchange. The functionalized ILs were designed and synthesized with the goal of obtaining adjustable wettability. The wettability of the graphene surface bearing various anions was measured systematically. The effect of solvent systems on ion exchange ratios on the graphene surface has also been investigated. Meanwhile, the mechanical properties of the graphene/IL composite films were investigated on a nanometer scale. The elasticity and adhesion behavior of the thin film was determined with respected to the indentation deformation by colloid probe nanoindentation method. The results indicate that anions played an important role in determining graphene/IL composite film properties. In addition, surface wetting and mechanics can be quantitatively determined according to the counter-anions on the surface. This study might suggest an alternate way for quantity detection of surface ions by surface force. PMID:24970602

  1. Ion-exchange behavior of alkali metals on treated carbons

    SciTech Connect

    Mohiuddin, G.; Hata, W.Y.; Tolan, J.S.

    1983-01-01

    The ion-exchange behavior of trace quantities of the alkali-metal ions sodium and cesium, on activated carbon impregnated with zirconium phosphate (referred to here as ZrP), was studied. Impregnated carbon had twice as much ion-exchange activity as unimpregnated, oxidized carbon, and 10 times as much as commercial activated carbons. The distribution coefficient of sodium increased with increasing pH; the distribution coefficient of cesium decreased with increasing pH. Sodium and cesium were separated with an electrolytic solution of 0.1 M HCl. Preliminary studies indicated that 0.2 M potassium and cesium can also be separated. Distribution coefficients of the supported ZrP were determined by the elution technique and agreed within 20% of the values for pure ZrP calculated from the literature.

  2. Separation of americium from curium by oxidation and ion exchange.

    PubMed

    Burns, Jonathan D; Shehee, Thomas C; Clearfield, Abraham; Hobbs, David T

    2012-08-21

    Nuclear energy has the potential to be a clean alternative to fossil fuels, but in order for it to play a major role in the US, many questions about the back end of the fuel cycle must be addressed. One of these questions is the difficult separation of americium from curium. Here, we report the oxidation of Am in two systems, perchloric acid and nitric acid and the affect of changing the acid has on the oxidation. K(d) values were observed and a direct separation factor was calculated and was seen to be as high as 20 for four metal(IV) pillared phosphate phosphonate inorganic organic hybrid ion exchange materials. These ion exchangers are characterized by very low selectivity for cations with low charge but extremely high uptake of ions of high charge.

  3. The dynamics of reductive sorption of oxygen by a granular bed of electron-ion exchangers with different copper dispersities

    NASA Astrophysics Data System (ADS)

    Konev, D. V.; Kravchenko, T. A.; Kalinichev, A. I.; Kipriyanova, E. S.

    2009-05-01

    The behavior of an immobile granular sorbent bed in one-component sorption in a column reactor is described in terms of the kinetic model of redox sorption taking into consideration the dispersity of metal particles, their radial distribution, peculiarities of chemical oxidation, and the relation of the overall rate of the process to the properties of the ion exchange matrix. The mathematical problem is formulated and solved numerically; the solution is analyzed theoretically in relation to the basic parameters of the sorption system. A satisfactory agreement is obtained between the experimental and calculated data on the reductive sorption of molecular oxygen from water on a copper-containing electron-ion exchanger.

  4. Oxygen-isotope exchange rates for three isostructural polyoxometalate ions.

    PubMed

    Villa, Eric M; Ohlin, C André; Casey, William H

    2010-04-14

    We compare oxygen-isotope exchange rates for all structural oxygens in three polyoxoniobate ions that differ by systematic metal substitutions of Ti(IV) --> Nb(V). The [H(x)Nb(10)O(28)]((6-x)-), [H(x)TiNb(9)O(28)]((7-x)-), and [H(x)Ti(2)Nb(8)O(28)]((8-x)-) ions are all isostructural yet have different Brønsted properties. Rates for sites within a particular molecule in the series differ by at least approximately 10(4), but the relative reactivities of the oxygen sites rank in nearly the same relative order for all ions in the series. Within a single ion, most structural oxygens exhibit rates of isotopic exchange that vary similarly with pH, indicating that each structure responds as a whole to changes in pH. Across the series of molecules, however, the pH dependencies for isotope exchanges and dissociation are distinctly different, reflecting different contributions from proton- or base-enhanced pathways. The proton-enhanced pathway for isotope exchange dominates at most pH conditions for the [H(x)Ti(2)Nb(8)O(28)]((8-x)-) ion, but the base-enhanced pathways are increasingly important for the [H(x)TiNb(9)O(28)]((7-x)-) and [H(x)Nb(10)O(28)]((6-x)-) structures at higher pH. The local effect of Ti(IV) substitution could be assessed by comparing rates for structurally similar oxygens on each side of the [H(x)TiNb(9)O(28)]((7-x)-) ion and is surprisingly small. Interestingly, these nanometer-size structures seem to manifest the same general averaged amphoteric chemistry that is familiar for other reactions affecting oxides in water, including interface dissolution by proton- and hydroxyl-enhanced pathways.

  5. Using ion exchange chromatography to purify a recombinantly expressed protein.

    PubMed

    Duong-Ly, Krisna C; Gabelli, Sandra B

    2014-01-01

    Ion exchange chromatography (IEX) separates molecules by their surface charge, a property that can vary vastly between different proteins. There are two types of IEX, cation exhange and anion exchange chromatography. The protocol that follows was designed by the authors for anion exchange chromatography of a recombinantly expressed protein having a pI of 4.9 and containing two cysteine residues and one tryptophan residue, using an FPLC system. Prior to anion exchange, the protein had been salted out using ammonium sulfate precipitation and partially purified via hydrophobic interaction chromatography (see Salting out of proteins using ammonium sulfate precipitation and Use and Application of Hydrophobic Interaction Chromatography for Protein Purification). Slight modifications to this protocol may be made to accommodate both the protein of interest and the availability of equipment.

  6. Isotope exchange kinetics in metal hydrides I : TPLUG model.

    SciTech Connect

    Larson, Rich; James, Scott Carlton; Nilson, Robert H.

    2011-05-01

    pronounced deviations at long times. These discrepancies can be overcome by postulating the presence of a surface poison such as carbon monoxide, but this explanation is highly speculative. When the method is applied to D {yields} H exchanges intentionally poisoned by known amounts of CO, the fitting results are noticeably degraded from those for the nominally CO-free system but are still tolerable. When TPLUG is used to simulate a blowdown-type experiment, which is characterized by large and rapid changes in both pressure and temperature, discrepancies are even more apparent. Thus, it can be concluded that the best use of TPLUG is not in simulating realistic exchange scenarios, but in extracting preliminary estimates for the kinetic parameters from experiments in which variations in temperature and pressure are intentionally minimized.

  7. Highly sensitive determination of hydrazine ion by ion-exclusion chromatography with ion-exchange enhancement of conductivity detection.

    PubMed

    Mori, Masanobu; Tanaka, Kazuhiko; Xu, Qun; Ikedo, Mikaru; Taoda, Hiroshi; Hu, Wenzhi

    2004-06-11

    An ion-exclusion chromatography method with ion-exchange enhancement of conductivity was developed for the selective separation and sensitive determination of hydrazine ion from alkali/alkaline earth metal cations and ammonium ion. Hydrazine ion was separated by ion-exclusion/penetration effect from other cations on a weakly basic anion-exchange column in the OH- form (TSKgel DEAE-5PW). Moreover, two different ion-exchange resin columns were inserted between the separating column and conductimetric detector in order to improve the sensitivity of hydrazine ion. The first enhancement column packed with a strongly basic anion-exchange resin in the SO4(2-) form (TSKgel SAX) for hydrazine ion can convert from N2H5OH to (N2H5)2SO4. Moreover, the second enhancement column packed with a strongly acidic cation-change resin in the H+ form (TSKgel SCX) can convert to H2SO4. As a result, the sensitivity of hydrazine ion using two conductivity enhancement columns could be 26.8-times greater than using the separating column alone. This method was effectiveness also for the enhancement of ammonium ion (6.1-times) and sodium ion (1.2-times). The calibration graph of hydrazine ion detected as H2SO4 was linear over the concentration range of 0.001-100 ppm (r2 = 0.9988). The detection limit of hydrazine ion in this system was 0.64 ppb. Therefore, hydrazine ion in real boiler water sample could be accurately determined, avoiding the interference of other cations.

  8. Studies on the solid-state ion exchange of nickel ions into zeolites using DRS technique

    NASA Astrophysics Data System (ADS)

    Zanjanchi, M. A.; Ebrahimian, A.

    2004-05-01

    The coordination of Ni 2+ ions in the dehydrated nickel-exchanged zeolites was investigated from the analysis of diffuse reflectance spectra. Solid-state ion exchange method was used to prepare nickel-containing mordenite, Y, L and mazzite zeolites. In the dehydrated mordenite and zeolite Y, nickel cations are presented in both forms of tetrahedral and distorted tetrahedral symmetries. The relative amount of tetrahedral and distorted tetrahedral nickel species are related to the heating temperature and heating time used for calcinations. In the dehydrated zeolite L and mazzite, Ni 2+ ions are mainly in the distorted octahedral symmetries.

  9. Synthesis and Ion-Exchange Properties of Graphene Th(IV) Phosphate Composite Cation Exchanger: Its Applications in the Selective Separation of Lead Metal Ions.

    PubMed

    Rangreez, Tauseef Ahmad; Asiri, Abdullah M; Alhogbi, Basma G; Naushad, Mu

    2017-07-24

    In this study, graphene Th(IV) phosphate was prepared by sol-gel precipitation method. The ion-exchange behavior of this cation-exchanger was studied by investigating properties like ion-exchange capacity for various metal ions, the effect of eluent concentration, elution behavior, and thermal effect on ion-exchange capacity (IEC). Several physicochemical properties as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) study, thermal studies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies were also carried out. The material possessed an IEC of 1.56 meq·dry·g(-1) of the exchanger and was found to be nano-composite. The selectivity studies showed that the material is selective towards Pb(II) ions. The selectivity of this cation-exchanger was demonstrated in the binary separation of Pb(II) ions from mixture with other metal ions. The recovery was found to be both quantitative and reproducible.

  10. Ion kinetic scale in the solar wind observed.

    PubMed

    Śafránková, Jana; Němeček, Zdeněk; Přech, Lubomír; Zastenker, Georgy N

    2013-01-11

    This Letter shows the first results from the solar wind monitor onboard the Spektr-R spacecraft which measures plasma moments with a time resolution of 31 ms. This high-time resolution allows us to make direct observations of solar wind turbulence below ion kinetic length scales. We present examples of the frequency spectra of the density, velocity, and thermal velocity. Our study reveals that although these parameters exhibit the same behavior at the magnetohydrodynamic scale, their spectra are remarkably different at the kinetic scale.

  11. Potentiometric sensors with ion-exchange Donnan exclusion membranes.

    PubMed

    Grygolowicz-Pawlak, Ewa; Crespo, Gastón A; Ghahraman Afshar, Majid; Mistlberger, Günter; Bakker, Eric

    2013-07-02

    Potentiometric sensors that exhibit a non-Hofmeister selectivity sequence are normally designed by selective chemical recognition elements in the membrane. In other situations, when used as detectors in separation science, for example, membranes that respond equally to most ions are preferred. With so-called liquid membranes, a low selectivity is difficult to accomplish since these membranes are intrinsically responsive to lipophilic species. Instead, the high solubility of sample lipids in an ionophore-free sensing matrix results in a deterioration of the response. We explore here potentiometric sensors on the basis of ion-exchange membranes commonly used in fuel cell applications and electrodialysis, which have so far not found their way into the field of ion-selective electrodes. These membranes act as Donnan exclusion membranes as the ions are not stripped of their hydration shell as they interact with the membrane. Because of this, lipophilic ions are no longer preferred over hydrophilic ones, making them promising candidates for the detection of abundant ions in the presence of lipophilic ones or as detectors in separation science. Two types of cation-exchanger membranes and one anion-exchange membrane were characterized, and potentiometric measuring ranges were found to be Nernstian over a wide range down to about 10 μM concentrations. Depending on the specific membrane, lipophilic ions gave equal response to hydrophilic ones or were even somewhat discriminated. The medium and long-term stability and reproducibility of the electrode signals were found to be promising when evaluated in synthetic and whole blood samples.

  12. Global simulation of field-reversed configuration using fully kinetic ion and drift kinetic electron

    NASA Astrophysics Data System (ADS)

    Lau, Calvin; Fulton, Daniel; Kuley, Animesh; Bao, Jian; Lin, Zhihong; Binderbauer, Michael; Tajima, Toshiki; Schmitz, Lothar; the TAE Team Team

    2016-10-01

    In the last several years, the C-2/C-2U advanced beam-driven field-reversed configuration (FRC) experiments at Tri Alpha Energy have progressed to consistent, reproducible plasma lifetimes of 10+ ms, i.e. FRCs have reached transport limited regimes. In FRC geometry, the thermal ion gyroradius is on the order of the size of the plasma near the magnetic null-point. Fast ion orbits intersect both the FRC core and the scrape-off layer (SOL) regions. Previous local simulations of electrostatic drift-wave instabilities using the Gyrokinetic Toroidal Code (GTC) find the core to be robustly stable with driftwave instability only in the SOL at frequencies approaching the ion cyclotron frequency. Therefore, FRC transport studies require fully kinetic ion simulations with cross-separatrix coupling between the core and SOL. Here we report progress of such global simulations using fully kinetic ions and drift kinetic electrons, including the implementation of the Boris push scheme for cyclotron motion and cylindrical coordinates for the separatrix. Supported by the Norman Rostoker Fellowship.

  13. Mechanism of extracellular ion exchange and binding-site occlusion in a sodium/calcium exchanger

    DOE PAGES

    Liao, Jun; Marinelli, Fabrizio; Lee, Changkeun; ...

    2016-05-16

    Na+/Ca2+ exchangers utilize the Na+ electrochemical gradient across the plasma membrane to extrude intracellular Ca2+, and play a central role in Ca2+ homeostasis. Here, we elucidate their mechanisms of extracellular ion recognition and exchange through a structural analysis of the exchanger from Methanococcus jannaschii (NCX_Mj) bound to Na+, Ca2+ or Sr2+ in various occupancies and in an apo state. This analysis defines the binding mode and relative affinity of these ions, establishes the structural basis for the anticipated 3:1Na+/Ca2+ exchange stoichiometry, and reveals the conformational changes at the onset of the alternating-access transport mechanism. An independent analysis of the dynamicsmore » and conformational free-energy landscape of NCX_Mj in different ion-occupancy states, based on enhanced-sampling molecular-dynamics simulations, demonstrates that the crystal structures reflect mechanistically relevant, interconverting conformations. Lastly, these calculations also reveal the mechanism by which the outward-to-inward transition is controlled by the ion-occupancy state, thereby explaining the emergence of strictly-coupled Na+/Ca2+ antiport.« less

  14. Mechanism of extracellular ion exchange and binding-site occlusion in the sodium-calcium exchanger

    PubMed Central

    Lee, ChangKeun; Huang, Yihe; Faraldo-Gómez, José D.; Jiang, Youxing

    2016-01-01

    Na+/Ca2+ exchangers utilize the Na+ electrochemical gradient across the plasma membrane to extrude intracellular Ca2+, and play a central role in Ca2+ homeostasis. Here, we elucidate their mechanisms of extracellular ion recognition and exchange through a structural analysis of the exchanger from Methanococcus jannaschii (NCX_Mj) bound to Na+, Ca2+ or Sr2+ in various occupancies and in an apo state. This analysis defines the binding mode and relative affinity of these ions, establishes the structural basis for the anticipated 3Na+:1Ca2+ exchange stoichiometry, and reveals the conformational changes at the onset of the alternating-access transport mechanism. An independent analysis of the dynamics and conformational free-energy landscape of NCX_Mj in different ion-occupancy states, based on enhanced-sampling molecular-dynamics simulations, demonstrates that the crystal structures reflect mechanistically relevant, interconverting conformations. These calculations also reveal the mechanism by which the outward-to-inward transition is controlled by the ion-occupancy state, thereby explaining the emergence of strictly-coupled Na+/Ca2+ antiport. PMID:27183196

  15. Mechanism of extracellular ion exchange and binding-site occlusion in a sodium/calcium exchanger

    SciTech Connect

    Liao, Jun; Marinelli, Fabrizio; Lee, Changkeun; Huang, Yihe; Faraldo-Gomez, Jose D.; Jiang, Youxing

    2016-05-16

    Na+/Ca2+ exchangers utilize the Na+ electrochemical gradient across the plasma membrane to extrude intracellular Ca2+, and play a central role in Ca2+ homeostasis. Here, we elucidate their mechanisms of extracellular ion recognition and exchange through a structural analysis of the exchanger from Methanococcus jannaschii (NCX_Mj) bound to Na+, Ca2+ or Sr2+ in various occupancies and in an apo state. This analysis defines the binding mode and relative affinity of these ions, establishes the structural basis for the anticipated 3:1Na+/Ca2+ exchange stoichiometry, and reveals the conformational changes at the onset of the alternating-access transport mechanism. An independent analysis of the dynamics and conformational free-energy landscape of NCX_Mj in different ion-occupancy states, based on enhanced-sampling molecular-dynamics simulations, demonstrates that the crystal structures reflect mechanistically relevant, interconverting conformations. Lastly, these calculations also reveal the mechanism by which the outward-to-inward transition is controlled by the ion-occupancy state, thereby explaining the emergence of strictly-coupled Na+/Ca2+ antiport.

  16. Mechanism of extracellular ion exchange and binding-site occlusion in a sodium/calcium exchanger

    SciTech Connect

    Liao, Jun; Marinelli, Fabrizio; Lee, Changkeun; Huang, Yihe; Faraldo-Gomez, Jose D.; Jiang, Youxing

    2016-05-16

    Na+/Ca2+ exchangers utilize the Na+ electrochemical gradient across the plasma membrane to extrude intracellular Ca2+, and play a central role in Ca2+ homeostasis. Here, we elucidate their mechanisms of extracellular ion recognition and exchange through a structural analysis of the exchanger from Methanococcus jannaschii (NCX_Mj) bound to Na+, Ca2+ or Sr2+ in various occupancies and in an apo state. This analysis defines the binding mode and relative affinity of these ions, establishes the structural basis for the anticipated 3:1Na+/Ca2+ exchange stoichiometry, and reveals the conformational changes at the onset of the alternating-access transport mechanism. An independent analysis of the dynamics and conformational free-energy landscape of NCX_Mj in different ion-occupancy states, based on enhanced-sampling molecular-dynamics simulations, demonstrates that the crystal structures reflect mechanistically relevant, interconverting conformations. Lastly, these calculations also reveal the mechanism by which the outward-to-inward transition is controlled by the ion-occupancy state, thereby explaining the emergence of strictly-coupled Na+/Ca2+ antiport.

  17. Environmentally benign hardness removal using ion-exchange fibers and snowmelt.

    PubMed

    Greenleaf, John E; Sengupta, Arup K

    2006-01-01

    Many industrial unit operations and unit processes require near-complete removal of hardness to avoid scaling in heat-transfer equipment, fouling in membranes, and high consumption of detergents and sequestering chemicals in cooling and wash water. Lime softening and cation exchange are the most commonly used processes practiced to date for hardness removal. Herein, we report and discuss the results and attributes of a new hardness removal process using ion-exchange fibers (IX-fibers). Most importantly, the process uses harvested snowmelt (or rainwater) as the regenerant chemical along with sparged carbon dioxide. Consequently, the spent regenerant does not contain a high concentration of aggressive chemicals such as sodium chloride or acid like traditional ion-exchange processes nor does the process produce voluminous sludges similar to lime softening. The bulk of carbon dioxide consumed during regeneration remains sequestered in the aqueous phase as alkalinity. IX-fibers form the heart of the process. They are essentially thin cylindrical polymeric strands 10-20 microm in diameter. The weak-acid carboxylate functional groups reside near to the surface of these cylindrical fibers. Low intraparticle diffusional resistance is the underlying reason IX-fibers are amenable to efficient regeneration with snowmelt sparged with carbon dioxide. When the carbon dioxide partial pressure is increased to 6.8 atm, over 90% calcium desorption efficiency is obtained. On the contrary, commercial weak-acid ion-exchange resins in spherical bead forms are ineffective for regeneration with carbon-dioxide-sparged snowmelt due to extremely slow ion-exchange kinetics involving counter-transport of Ca2+ and H+.

  18. Grafted megaporous materials as ion-exchangers for bioproduct adsorption.

    PubMed

    Bibi, Noor Shad; Fernández-Lahore, Marcelo

    2013-01-01

    Megaporous chromatographic materials were manufactured by a three-step procedure, including backbone synthesis, chemical grafting, and introduction of ion-exchange functionality. The backbone of the adsorbent cylindrical bodies was prepared by polymerization of methacrylic acid and poly(ethylene glycol) diacrylate at sub-zero temperatures. Grafting was performed employing glycidyl methacrylate and a chemical initiator, cerium ammonium nitrate. The degree of grafting was adjusted by modifying the concentration of the initiator in the reaction mixture to a range of values (23, 39, 62, 89, and 105%). Further, the pendant epoxy-groups generated by the previous step were reacted to cation- and anion-exchanging moieties utilizing known chemical routes. Infrared spectroscopy studies confirmed the incorporation of epoxy and ion-exchanger groups to the backbone material. Optimized materials were tested for chromatography applications with model proteins; the dynamic binding capacity, as recorded at 10% breakthrough and 2.0 × 10(-4) m/s superficial velocity, were 350 and 58 mg/g for the cation-exchanger and the anion-exchanger material, respectively. These results may indicate that long tentacle-type polymer brushes were formed during grafting therefore increasing the ability of the megaporous body to efficiently capture macromolecules.

  19. Field performance of GCL under ion exchange conditions

    SciTech Connect

    James, A.N.; Fullerton, D.; Drake, R.

    1997-10-01

    Five Victorian reservoirs of brick pillar and arch construction were renovated using geosynthetic clay liners (also called bentonite/geosynthetic composites) (GCL) as roof sealing materials. The GCL was predominantly sodium bentonite and contained some 2% of calcite. GCLs were laid on leveled, original puddled clay packed between and above the brick arches. There was an overlying gravel layer connected to a drainage system that, in turn, was covered with soil and seeded with grass. Leaks through roofs into stored potable water were discovered. Excavation and exposure of the GCL showed that they were finely cracked in many places. Samples of the GCL bentonite from several locations at each of five sites had a high moisture content. Also, the GCL had a much reduced exchangeable sodium and increased exchangeable calcium content when compared to the dry unused GCL. Laboratory experiments, lasting for a limited period, were carried out to simulate operating conditions of the GCL whereby water falling on the ground and reaching the GCL flowed across the GCL in the overlying gravel layer to collector drains. Similar but less extensive ion exchange, calcium for sodium, was found here also. The evidence demonstrates that calcium from calcite, contained in the GCL bentonite, exchanged with sodium and, in so doing, contributed to shrinkage and cracking. Supplementary sources of calcium for ion exchange probably came from overlying calcareous soil and water from firehoses used to field test the integrity of the GCL.

  20. Ion-exchange chromatographic analysis of peroxynitric acid.

    PubMed

    Nakashima, Yoichi; Ikawa, Satoshi; Tani, Atsushi; Kitano, Katsuhisa

    2016-01-29

    Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system. The fraction for the peroxynitric acid peak was collected. Ion-exchange chromatographic analysis of this fraction, after standing at room temperature for 24h, showed that the decomposition products were mainly nitrate ions with a very small amount of nitrous acid. The peroxynitric acid peak area correlated perfectly with the total amount of decomposition products. The ion-exchange chromatographic isolation allowed us to evaluate the molar extinction coefficient of peroxynitric acid precisely in a wider wavelength range than previous reports. The value decreases monotonically from 1729±26M(-1)cm(-1) at 200nm to 12.0±0.5M(-1)cm(-1) at 290nm. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Charge-exchange plasma generated by an ion thruster

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.

    1975-01-01

    The use of high voltage solar arrays greatly reduces or eliminates power processing requirements in space electric propulsion systems. This use also requires substantial areas of solar array to be at high positive potential relative to space and most of the spacecraft. The charge exchange plasma conducts electrons from the ion beam to such positive surfaces, and thereby electrically load the high voltage solar array. To evaluate this problem, the charge-exchange plasma generated by an ion beam was investigated experimentally. Based upon the experimental data, a simple model was derived for the charge-exchange plasma. This model is conservative in the sense that both the electron/ion density and the electron current density should be equal to, or less than, the preducted value for all directions in the hemisphere upstream of the ion beam direction. Increasing the distance between a positive potential surface (such as a high voltage solar array) and the thruster is the simplest way to control interactions. Both densities and currents vary as the inverse square of this distance.

  2. The role of humic non-exchangeable binding in the promotion of metal ion transport in groundwaters in the environment.

    PubMed

    Bryan, Nick D; Jones, Dominic L M; Keepax, Rose E; Farrelly, Dean H; Abrahamsen, Liam G; Pitois, Aurelien; Ivanov, Peter; Warwick, Peter; Evans, Nick

    2007-04-01

    Metal ions form strong complexes with humic substances. When the metal ion is first complexed by humic material, it is bound in an 'exchangeable' mode. The metal ion in this fraction is strongly bound, however, if the metal-humic complex encounters a stronger binding site on a surface, then the metal ion may dissociate from the humic substance and be immobilised. However, over time, exchangeably-bound metal may transfer to a 'non-exchangeable' mode. Transfer into this mode and dissociation from it are slow, regardless of the strength of the competing sink, and so immobilisation may be hindered. A series of coupled chemical transport calculations has been performed to investigate the likely effects of non-exchangeable binding upon the transport of metal ions in the environment. The calculations show that metal in the non-exchangeable mode will have a significantly higher mobility than that in the exchangeable mode. The critical factor is the ratio of the non-exchangeable first-order dissociation rate constant and the residence time in the groundwater column, metal ion mobility increasing with decreasing rate constant. A second series of calculations has investigated the effect of the sorption to surfaces of humic/metal complexes on the transport of the non-exchangeably bound metal. It was found that such sorption may reduce mobility, depending upon the humic fraction to which the metal ion is bound. For the more weakly sorbing humic fractions, under ambient conditions (humic concentration etc.) the non-exchangeable fraction may still transport significantly. However, for the more strongly sorbed fractions, the non-exchangeable fraction has little effect upon mobility. In addition to direct retardation, sorption also increases the residence time of the non-exchangeable fraction, giving more time for dissociation and immobilisation. The non-exchangeable dissociation reaction, and the sorption reaction have been classified in terms of two Damkohler numbers, which can

  3. Demonstration of an Ion Exchange Resin Addition/Removal System with Superlig 659

    SciTech Connect

    Norato, M.A.

    2000-12-19

    A pilot facility was designed and built in the Thermal Fluids Laboratory at the Savannah River Technology Center to demonstrate the slurry transport of ion exchange resins in and out of ion exchange columns.

  4. Estimation of ion channel kinetics from fluctuations of macroscopic currents.

    PubMed

    Moffatt, Luciano

    2007-07-01

    For single channel recordings, the maximum likelihood estimation (MLE) of kinetic rates and conductance is well established. A direct extrapolation of this method to macroscopic currents is computationally prohibitive: it scales as a power of the number of channels. An approximated MLE that ignored the local time correlation of the data has been shown to provide estimates of the kinetic parameters. In this article, an improved approximated MLE that takes into account the local time correlation is proposed. This method estimates the channel kinetics using both the time course and the random fluctuations of the macroscopic current generated by a homogeneous population of ion channels under white noise. It allows arbitrary kinetic models and stimulation protocols. The application of the proposed algorithm to simulated data from a simple three-state model on nonstationary conditions showed reliable estimates of all the kinetic constants, the conductance and the number of channels, and reliable values for the standard error of those estimates. Compared to the previous approximated MLE, it reduces by a factor of 10 the amount of data needed to secure a given accuracy and it can even determine the kinetic rates in macroscopic stationary conditions.

  5. Estimation of Ion Channel Kinetics from Fluctuations of Macroscopic Currents

    PubMed Central

    Moffatt, Luciano

    2007-01-01

    For single channel recordings, the maximum likelihood estimation (MLE) of kinetic rates and conductance is well established. A direct extrapolation of this method to macroscopic currents is computationally prohibitive: it scales as a power of the number of channels. An approximated MLE that ignored the local time correlation of the data has been shown to provide estimates of the kinetic parameters. In this article, an improved approximated MLE that takes into account the local time correlation is proposed. This method estimates the channel kinetics using both the time course and the random fluctuations of the macroscopic current generated by a homogeneous population of ion channels under white noise. It allows arbitrary kinetic models and stimulation protocols. The application of the proposed algorithm to simulated data from a simple three-state model on nonstationary conditions showed reliable estimates of all the kinetic constants, the conductance and the number of channels, and reliable values for the standard error of those estimates. Compared to the previous approximated MLE, it reduces by a factor of 10 the amount of data needed to secure a given accuracy and it can even determine the kinetic rates in macroscopic stationary conditions. PMID:17416622

  6. Physics and chemistry of antimicrobial behavior of ion-exchanged silver in glass.

    PubMed

    Borrelli, N F; Senaratne, W; Wei, Y; Petzold, O

    2015-02-04

    The results of a comprehensive study involving the antimicrobial activity in a silver ion-exchanged glass are presented. The study includes the glass composition, the method of incorporating silver into the glass, the effective concentration of the silver available at the glass surface, and the effect of the ambient environment. A quantitative kinetic model that includes the above factors in predicting the antimicrobial activity is proposed. Finally, experimental data demonstrating antibacterial activity against Staphylococcus aureus with correlation to the predicted model is shown.

  7. THE ION-INDUCED CHARGE-EXCHANGE X-RAY EMISSION OF THE JOVIAN AURORAS: MAGNETOSPHERIC OR SOLAR WIND ORIGIN?

    SciTech Connect

    Hui Yawei; Schultz, David R.; Kharchenko, Vasili A.; Stancil, Phillip C.; Cravens, Thomas E.; Lisse, Carey M. E-mail: schultzd@ornl.gov E-mail: stancil@physast.uga.edu E-mail: carey.lisse@jhuapl.edu

    2009-09-10

    A new and more comprehensive model of charge-exchange induced X-ray emission, due to ions precipitating into the Jovian atmosphere near the poles, has been used to analyze spectral observations made by the Chandra X-ray Observatory. The model includes for the first time carbon ions, in addition to the oxygen and sulfur ions previously considered, in order to account for possible ion origins from both the solar wind and the Jovian magnetosphere. By comparing the model spectra with newly reprocessed Chandra observations, we conclude that carbon ion emission provides a negligible contribution, suggesting that solar wind ions are not responsible for the observed polar X-rays. In addition, results of the model fits to observations support the previously estimated seeding kinetic energies of the precipitating ions ({approx}0.7-2 MeV u{sup -1}), but infer a different relative sulfur-to-oxygen abundance ratio for these Chandra observations.

  8. The Ion-induced Charge-exchange X-ray Emission of the Jovian Auroras: Magnetospheric or Solar Wind Origin?

    SciTech Connect

    Hui, Yawei; Schultz, David Robert; Kharchenko, Vasili A; Stancil, Phillip C.; Cravens, Thomas E. E.; Lisse, Carey M.; Dalgarno, A.

    2009-01-01

    A new and more comprehensive model of charge-exchange induced X-ray emission, due to ions precipitating into the Jovian atmosphere near the poles, has been used to analyze spectral observations made by the Chandra X-ray Observatory. The model includes for the first time carbon ions, in addition to the oxygen and sulfur ions previously considered, in order to account for possible ion origins from both the solar wind and the Jovian magnetosphere. By comparing the model spectra with newly reprocessed Chandra observations, we conclude that carbon ion emission provides a negligible contribution, suggesting that solar wind ions are not responsible for the observed polar X-rays. In addition, results of the model fits to observations support the previously estimated seeding kinetic energies of the precipitating ions ( 0.7-2 MeV/u), but infer a different relative sulfur to oxygen abundance ratio for these Chandra observations.

  9. Thermodynamics of overequivalent sorption in multicomponent ion-exchange systems with amino acids

    NASA Astrophysics Data System (ADS)

    Khokhlova, O. N.; Khokhlov, V. Yu.; Bashlykova, O. Yu.; Trunaeva, E. S.

    2017-04-01

    Ion exchange and overoverequivalent sorption in the AV-17-2P-OH-Cl-tryptophan anion-exchange system are studied. It is established that the ion exchange of tryptophan against the background of the exchange of mineral ions (OH--Cl-) is better accomplished from alkaline solutions on the Cl- form of the adsorbent and the overequivalent adsorption of an amino acid from a salt-containing solution on the OH- form of the anion exchange resin. The results from calculating and analyzing the thermodynamic constants of ion exchange and non-exchange absorption are given.

  10. Syntesis of lanthanum zirconate hydrosols by the ion exchange method

    NASA Astrophysics Data System (ADS)

    Bovina, E. A.; Tarasova, J. V.; Chibirova, F. Kh

    2011-04-01

    Ion exchange of LaCl3 and ZrOCl2 aqueous solutions with anion-exchanger AV-17-8 was used to synthesize finely dispersed hydrosol of amorphous lanthanum zirconate La2Zr2O7. Heat treatment of dried La2Zr2O7 hydrosols at 700°C and 1100°C resulted in the formation of powders with fluorite and pyrochlore type structures, respectively. Epitaxial La2Zr2O7 films were obtained on SrTiO3 (001) single crystals. The substrate has an influence on the lanthanum zirconate crystal orientation, as well as strong inhibitory effect on sintering processes.

  11. Kinetic study of ion-acoustic plasma vortices

    SciTech Connect

    Khan, S. A.; Aman-ur-Rehman; Mendonca, J. T.

    2014-09-15

    The kinetic theory of electron plasma waves with finite orbital angular momentum has recently been introduced by Mendonca. This model shows possibility of new kind of plasma waves and instabilities. We have extended the theory to ion-acoustic plasma vortices carrying orbital angular momentum. The dispersion equation is derived under paraxial approximation which exhibits a kind of linear vortices and their Landau damping. The numerical solutions are obtained and compared with analytical results which are in good agreement. The physical interpretation of the ion-acoustic plasma vortices and their Landau resonance conditions are given for typical case of Maxwellian plasmas.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  13. Kinetics of chromium ion absorption by cross-linked polyacrylate films

    NASA Technical Reports Server (NTRS)

    May, C. E.

    1984-01-01

    Three cross-linked ion exchange membranes were studied as to their ability to absorb chromium ion from aqueous chromium III nitrate solutions. Attention was given to the mechanism of absorption, composition of the absorbed product, and the chemical bonding. The membranes were: calcium polyacrylate, polyacrylic acid, and a copolymer of acrylic acid and vinyl alcohol. For the calcium polyacrylate and the copolymer, parabolic kinetics were observed, indicating the formation of a chromium polyacrylate phase as a coating on the membrane. The rate of absorption is controlled by the diffusion of the chromium ion through this coating. The product formed in the copolymer involves the formation of a coordination complex of a chromium ion with 6 carboxylic acid groups from the same molecule. The absorption of the chromium ion by the polyacrylic acid membranes appears to be more complicated, involving cross-linking. This is due to the coordination of the chromium ion with carboxylic acid groups from more than one polymer molecule. The absorption rate of the chromium ion by the calcium salt membrane was found to be more rapid than that by the free polyacrylic acid membrane.

  14. Mechanism Exploration of Ion Transport in Nanocomposite Cation Exchange Membranes.

    PubMed

    Tong, Xin; Zhang, Bopeng; Fan, Yilin; Chen, Yongsheng

    2017-04-19

    The origin of property enhancement of nanocomposite ion exchange membranes (IEMs) is far from being fully understood. By combining experimental work and computational modeling analysis, we could determine the influence of nanomaterials on the ion transport properties of nanocomposite cation exchange membranes (CEMs). We synthesized and characterized a series of nanocomposite CEMs by using SPPO as polymer materials and silica nanoparticles (NPs) (unsulfonated or sulfonated) as nanomaterials. We found that with the increase of NP loading, measured CEM permselectivity and swelling degree first increased and then decreased. We also found the ion exchange capacity (IEC) and ionic resistance of nanocomposite CEMs tend to be the same, regardless what type of NPs are incorporated into the membrane. Modeling analysis suggests that the change of membrane properties is related to the change in membrane microstructure. With the addition of silica NPs, membrane porosity (volume fraction of intergel phase) increases so that membranes can absorb more water. Also, volume fraction of sulfonated polymer segments increases, which can allow membranes to retain more counterions, causing membrane IEC to increase. By calculating the effective ion diffusion coefficients and membrane tortuosity factors of all the silica-NP-based CEMs synthesized in this study, along with nanocomposite CEMs from previous studies, we conclude that membrane ion transport efficiency tends to increase with the incorporation of nanomaterials. In addition, this paper presents a simulation model, which explains how the membrane property changes upon nanomaterial aggregation; the simulation results are in good agreement with the experimental data. Simulation results indicate that membrane properties are related to nanomaterial number concentration in the membrane matrices; thus, a plateau is reached for membrane ion diffusion coefficients due to the severe influence of aggregation on the increase of nanomaterial

  15. Kinetic modelling for zinc (II) ions biosorption onto Luffa cylindrica

    NASA Astrophysics Data System (ADS)

    Oboh, I.; Aluyor, E.; Audu, T.

    2015-03-01

    The biosorption of Zinc (II) ions onto a biomaterial - Luffa cylindrica has been studied. This biomaterial was characterized by elemental analysis, surface area, pore size distribution, scanning electron microscopy, and the biomaterial before and after sorption, was characterized by Fourier Transform Infra Red (FTIR) spectrometer. The kinetic nonlinear models fitted were Pseudo-first order, Pseudo-second order and Intra-particle diffusion. A comparison of non-linear regression method in selecting the kinetic model was made. Four error functions, namely coefficient of determination (R2), hybrid fractional error function (HYBRID), average relative error (ARE), and sum of the errors squared (ERRSQ), were used to predict the parameters of the kinetic models. The strength of this study is that a biomaterial with wide distribution particularly in the tropical world and which occurs as waste material could be put into effective utilization as a biosorbent to address a crucial environmental problem.

  16. Kinetic modelling for zinc (II) ions biosorption onto Luffa cylindrica

    SciTech Connect

    Oboh, I.; Aluyor, E.; Audu, T.

    2015-03-30

    The biosorption of Zinc (II) ions onto a biomaterial - Luffa cylindrica has been studied. This biomaterial was characterized by elemental analysis, surface area, pore size distribution, scanning electron microscopy, and the biomaterial before and after sorption, was characterized by Fourier Transform Infra Red (FTIR) spectrometer. The kinetic nonlinear models fitted were Pseudo-first order, Pseudo-second order and Intra-particle diffusion. A comparison of non-linear regression method in selecting the kinetic model was made. Four error functions, namely coefficient of determination (R{sup 2}), hybrid fractional error function (HYBRID), average relative error (ARE), and sum of the errors squared (ERRSQ), were used to predict the parameters of the kinetic models. The strength of this study is that a biomaterial with wide distribution particularly in the tropical world and which occurs as waste material could be put into effective utilization as a biosorbent to address a crucial environmental problem.

  17. Enigmatic ion-exchange behavior of myo-inositol phosphates.

    PubMed

    Shelor, C Phillip; Liao, Hongzhu; Kadjo, Akinde Florence; Dasgupta, Purnendu K

    2015-05-05

    The separation of myo-inositol mono-, di-, tri-, tetra-, pentakis-, and hexakisphosphate (InsP1, InsP2, InsP3, InsP4, InsP5, InsP6) was carried out using hydroxide eluent ion chromatography. Acid hydrolysis of InsP6 (phytate) was used to prepare a distribution of InsPs, ranging from InsP1 to InsP5's and including unhydrolyzed InsP6. Counting all possible positional isomers (many of which have stereoisomers that will not be separable by conventional ion exchange), 40 chromatographically separable peaks are possible; up to 22 were separated and identified by mass spectrometry. InsPs show unusual ion-exchange behavior in two respects: (a) the retention order is not monotonically related with the charge on the ion and (b) at the same hydroxide eluent concentration, retention is greatly dependent on the eluent metal cation. The retention of InsP3-InsP6 was determined to be controlled by steric factors while elution was influenced by eluent cation complexation. These highly phosphorylated InsPs have a much greater affinity for alkali metals (Li(+) > Na(+) > K(+)) than quaternary ammonium ions. This difference in cation affinity was exploited to improve separation through the use of a tetramethylammonium hydroxide-sodium hydroxide gradient.

  18. Ion exchange at the critical point of solution.

    PubMed

    Savoy, J D; Baird, J K; Lang, J R

    2016-03-11

    A mixture of isobutyric acid (IBA)+water has an upper critical point of solution at 26.7°C and an IBA concentration of 4.40M. We have determined the Langmuir isotherms for the hydroxide form of Amberlite IRN-78 resin in contact with mixtures of IBA+water at temperatures, 27.0, 29.0, 31.0 and 38.0°C, respectively. The Langmuir plot at 38.0°C forms a straight line. At the three lower temperatures, however, a peak in the Langmuir plot is observed for IBA concentrations in the vicinity of 4.40M. We regard this peak to be a critical effect not only because it is located close to 4.40M, but also because its height becomes more pronounced as the temperature of the isotherm approaches the critical temperature. For concentrations in the vicinity of the peak, the data indicate that the larger isobutyrate ion is rejected by the resin in favor of the smaller hydroxide ion. This reversal of the expected ion exchange reaction might be used to separate ions according to size. Using the Donnan theory of ion exchange equilibrium, we link the swelling pressure to the osmotic pressure. We show that the peak in the Langmuir plot is associated with a maximum in the "osmotic" energy. This maximum has its origin in the concentration derivative of the osmotic pressure, which goes to zero as the critical point is approached.

  19. RECENT ADVANCES IN ION EXCHANGE MATERIALS AND PROCESSES FOR POLLUTION PREVENTION

    EPA Science Inventory

    The goal of this article was to summarize the recent advances in ion exchange technology for the metal finishing industry. Even though the ion exchange technology is mature and is widely employed in the industry, new applications, approaches and ion exchange materials are emergi...

  20. RECENT ADVANCES IN ION EXCHANGE MATERIALS AND PROCESSES FOR POLLUTION PREVENTION

    EPA Science Inventory

    The goal of this article was to summarize the recent advances in ion exchange technology for the metal finishing industry. Even though the ion exchange technology is mature and is widely employed in the industry, new applications, approaches and ion exchange materials are emergi...

  1. Isotope effects of neodymium in different ligands exchange systems studied by ion exchange displacement chromatography

    PubMed Central

    Ismail, Ibrahim; Fawzy, Ahmed S.; Ahmad, Mohammad I.; Aly, Hisham F.; Nomura, Masao; Fujii, Yasuhiko

    2012-01-01

    The isotope effects of neodymium in Nd-glycolate ligand exchange system were studied by using ion exchange chromatography. The separation coefficients of neodymium isotopes, ε’s, were calculated from the observed isotopic ratios at the front and rear boundaries of the neodymium adsorption band. The values of separation coefficients of neodymium isotopes, ε’s, for the Nd-glycolate ligand exchange system were compared with those of Nd-malate and Nd-citrate, which indicated that the isotope effects of neodymium as studied by the three ligands takes the following direction Malate > Citrate > Glycolate. This order agrees with the number of available sites for complexation of each ligand. The values of the plate height, HETP of Nd in Nd-ligand exchange systems were also calculated. PMID:25685410

  2. Novel tetrazole-functionalized ion exchanger for weak cation-exchange chromatography of proteins.

    PubMed

    Lei, Genhu; Xiong, Xiaohu; Wei, Yinmao; Zheng, Xiaohui; Zheng, Jianbin

    2008-04-11

    A new type of weak cation exchanger, tetrazole-functionalized silica, was developed for bioseparation. It was prepared conveniently by modifying silica gel initially with gamma-glycidoxypropyltrimethoxysilane, then with 3-hydroxypropionitrile and finally with ammonium-catalyzed (3+2) azide-nitrile cycloaddition, which is an element of click chemistry. The prepared stationary phase was characterized and evaluated for its separation performance, protein retention behavior, loading capacity, protein recovery and chemical stability. The results show that the stationary phase developed has excellent performance for protein separations with high mass recoveries, and has long-term stability. Some remarkable differences were observed between this new exchanger and a carboxylic methyl-functionalized ion exchanger, which is typically used in weak cation-exchange chromatography of proteins. The obtained column was also used for the purification of lysozyme from chicken egg white, and the purity and specific bioactivity of the obtained lysozyme were about 90% and 67 IU/mg, respectively.

  3. Isotope effects of neodymium in different ligands exchange systems studied by ion exchange displacement chromatography.

    PubMed

    Ismail, Ibrahim; Fawzy, Ahmed S; Ahmad, Mohammad I; Aly, Hisham F; Nomura, Masao; Fujii, Yasuhiko

    2013-03-01

    The isotope effects of neodymium in Nd-glycolate ligand exchange system were studied by using ion exchange chromatography. The separation coefficients of neodymium isotopes, ε's, were calculated from the observed isotopic ratios at the front and rear boundaries of the neodymium adsorption band. The values of separation coefficients of neodymium isotopes, ε's, for the Nd-glycolate ligand exchange system were compared with those of Nd-malate and Nd-citrate, which indicated that the isotope effects of neodymium as studied by the three ligands takes the following direction Malate > Citrate > Glycolate. This order agrees with the number of available sites for complexation of each ligand. The values of the plate height, HETP of Nd in Nd-ligand exchange systems were also calculated.

  4. Cesium Ion Exchange Program at the Hanford River Protection Project Waste Treatment Plant

    SciTech Connect

    CHARLES, NASH

    2005-02-27

    The Hanford Waste Treatment and Immobilization Plant (WTP) will use cesium ion exchange to remove Cs-137 from Low Activity Waste (LAW) down to a maximum activity of 0.3 Ci/m3 in the Immobilized LAW (ILAW) product. The WTP Project baseline for cesium ion exchange is the elutable SuperLig(R) 644 (SL-644) resin (registered trademark of IBC Advanced Technologies, Inc., American Fork, UT) or a U. S. Department of Energy (DOE) approved equivalent. SL-644 is solely available through IBC Advanced Technologies. The WTP Project is conducting a three-stage process for selecting and qualifying an alternative ion exchange resin. Resorcinol formaldehyde (RF) is being pursued as a potential alternative to SL-644, to provide a backup resin supply. Resin cost relative to SL-644 is a primary driver. Phase I of the testing plan examined the viability of RF resin and recommended that a spherical form of RF resin be examined further. Phases II and III, now underway, include batch testing to determine the isotherm of this resin, kinetics to address the impacts of bead diameter and high sodium feed levels on processing Hanford waste with the resin, and multicycle column testing to determine how temperature and chemical cycling affects waste processing. Phases II and III also examine resin performance against simulated WTP feeds, radiolytic and thermal stability, and scale-up to pilot scale performance. We will discuss early results obtained from Phase II testing here.

  5. Ion composition and kinetics in Mercury's magnetotail (Invited)

    NASA Astrophysics Data System (ADS)

    Gershman, D. J.; Slavin, J. A.; Raines, J. M.; Zurbuchen, T.; Anderson, B. J.; Korth, H.; Baker, D. N.; Solomon, S. C.

    2013-12-01

    We present the first targeted study of the kinetic properties of Mercury's magnetotail plasmas using three-dimensional data from the Fast Imaging Plasma Spectrometer sensor on the MESSENGER spacecraft. The average velocity distribution functions of both solar wind and planetary ions in the plasma sheet are consistent with hot, near-isotropic Maxwellian distributions, enabling an estimation of both density and temperature for each species. Although the temperature and density of the H+-dominated plasma sheet vary over the ranges ~2-20 cm-3 and ~5-30 MK, respectively, they maintain a nearly constant thermal pressure of ~0.75 nPa, sufficient to balance the observed diamagnetic depressions in Mercury's magnetotail magnetic field. Solar wind ions, namely He2+ and O6++C5+, retain near-solar-wind abundances with respect to H+ and exhibit mass-proportional ion temperatures. Conversely, planetary ion species such as He+, O+, and Na+ are accelerated to approximately the same average energies. Substantial heavy ion plasma content in the pre-midnight plasma sheet suggests that planetary ions may asymmetrically mass-load Mercury's magnetotail, though it remains to be seen whether the predicted quasi-adiabaticity of these ions permits them to dynamically influence the ambient plasma. No such asymmetry with respect to local midnight is evident in the measured planetary ion temperatures. The temperature of He2+ is strongly correlated with that of H+ in the plasma sheet, which scales linearly with upstream solar wind speed (vsw) due to the conversion of solar wind ram pressure to plasma thermal pressure across Mercury's bow shock. The temperature of Na+-group ions, however, increases only linearly with solar wind speed for vsw < 500 km/s. For vsw > 500 km/s, the temperature of Na+ remains near ~25 MK, suggesting the presence of a saturation effect in the energization process of planetary ions at Mercury.

  6. Radiation degradation in EPICOR-2 ion exchange resins

    SciTech Connect

    McConnell, J.W. Jr.; Johnson, D.A.; Sanders, R.D. Sr.

    1990-09-01

    The Low-Level Waste Data base Development -- EPICOR-II Resin/Liner Investigation Program funded by the US Nuclear Regulatory Commission is investigating chemical and physical conditions for organic ion exchange resins contained in several EPICOR-II prefilters. Those prefilters were used during cleanup of contaminated water from the Three Mile Island Nuclear Power Station after the March 1979 accident. The work was performed by EG G Idaho, Inc. at the Idaho Engineering Laboratory. This is the final report of this task and summarizes results and analyses of three samplings of ion exchange resins from prefilters PF-8 and -20. Results are compared with baseline data from tests performed on unirradiated resins supplied by Epicor, Inc. to determine the extent of degradation due to the high internal radiation dose received by the organic resins. Results also are compared with those of other researchers. 18 refs., 23 figs., 7 tabs.

  7. Design software for ion-exchanged glass waveguide devices

    NASA Astrophysics Data System (ADS)

    Tervonen, Ari; Honkanen, Seppo; Poyhonen, Pekka; Tahkokorpi, Markku T.

    1993-04-01

    Software tools for design of passive integrated optical components based on ion-exchanged glass waveguides have been developed. All design programs have been implemented on personal computers. A general simulation program for ion exchange processes is used for optimization of waveguide fabrication. The optical propagation in the calculated channel waveguide profiles is modelled with various methods. A user-friendly user's interface has been included in this modelling software. On the basis of the calculated propagation properties, performance of channel waveguide circuits can be modelled and thus devices for different applications may be designed. From the design parameters, the lithography mask pattern to be used is generated for a commercial CAD program for final mask design. Examples of designed and manufactured guided-wave devices are described. These include 1- to-n splitters and asymmetric Mach-Zehnder interferometers for wavelength division multiplexing.

  8. ION EXCHANGE PROCESS FOR THE RECOVERY AND PURIFICATION OF MATERIALS

    DOEpatents

    Long, R.S.; Bailes, R.H.

    1958-04-15

    A process for the recovery of certain metallic ions from aqueous solutions by ion exchange techniques is described. It is applicable to elements such as vanadium, chromium, nnanganese, and the like, which are capable of forming lower valent cations soluble in aqueous solutions and which also form ldgher valent anions soluble in aqueous acidic solutions. For example, small amounts of vanadium occurring in phosphoric acid prepared from phosphate rock may be recovered by reducing the vanadium to a trivalent cation adsorbing; the vanadium in a cationic exchange resin, then treating the resin with a suitable oxidizing agent to convert the adsorbed vanadium to a higher valent state, and finally eluting; the vanadium as an anion from the resin by means of an aqueous acidic solution.

  9. Hybrid metallic ion-exchanged waveguides for SPR biological sensing

    NASA Astrophysics Data System (ADS)

    de Bonnault, S.; Bucci, D.; Zermatten, P.. J.; Charette, P. G.; Broquin, J. E.

    2015-02-01

    Glass substrates have been used for decades to create biosensors due to their biocompatibility, low thermal conductivity, and limited fluorescence. Among the different types of sensors, those based on surface plasmon resonance (SPR) allow exploitation of the sensing lightwave at the vicinity of the sensor surface where small entities such as DNA or proteins are located. In this paper, ion-exchanged waveguides and SPR are combined to create a multianalyte optical sensor integrated onto glass. First the principle of operation is introduced, then the theoretical analysis and design of the sensing element. Simulations have been carried out using the Aperiodic Fourier Modal Method (AFMM) and a custom software that handles ion-exchange index-profiles. Fabrication and characterization processes are also presented. Finally the first experimental spectra are displayed and discussed. The sensor presents a bulk sensibility of 5000nm/RIU.

  10. Closed cycle ion exchange method for regenerating acids, bases and salts

    DOEpatents

    Dreyfuss, Robert M.

    1976-01-01

    A method for conducting a chemical reaction in acidic, basic, or neutral solution as required and then regenerating the acid, base, or salt by means of ion exchange in a closed cycle reaction sequence which comprises contacting the spent acid, base, or salt with an ion exchanger, preferably a synthetic organic ion-exchange resin, so selected that the counter ions thereof are ions also produced as a by-product in the closed reaction cycle, and then regenerating the spent ion exchanger by contact with the by-product counter ions. The method is particularly applicable to closed cycle processes for the thermochemical production of hydrogen.

  11. Momentum transfer in relativistic heavy ion charge-exchange reactions

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Wilson, J. W.; Khan, F.; Khandelwal, G. S.

    1991-01-01

    Relativistic heavy ion charge-exchange reactions yield fragments (Delta-Z = + 1) whose longitudinal momentum distributions are downshifted by larger values than those associated with the remaining fragments (Delta-Z = 1, -2,...). Kinematics alone cannot account for the observed downshifts; therefore, an additional contribution from collision dynamics must be included. In this work, an optical model description of collision momentum transfer is used to estimate the additional dynamical momentum downshift. Good agreement between theoretical estimates and experimental data is obtained.

  12. Electrodeposition of microparticles on polarized ion exchange membranes

    SciTech Connect

    Verbich, S.V.; Ponomarev, M.I.; Grebenyuk, V.D.; Dukhin, S.S.

    1986-11-01

    The use of ion exchange membranes to extract microparticles from an aqueous solution is considered. The efficiency of removing negatively charged aerosil particles depends substantially on the nature of the membrane located at the anode. It has been established that besides an increase in the electric field intensity the principal factor ensuring an increase in the efficiency of purifying a solution by electrodeposition of microparticles on a membrane surface is a reduction in the flowrate relative to the membrane surface.

  13. Separation of organic ion exchange resins from sludge -- engineering study

    SciTech Connect

    Duncan, J.B.

    1998-08-25

    This engineering study evaluates the use of physical separation technologies to separate organic ion exchange resin from KE Basin sludge prior to nitric acid dissolution. This separation is necessitate to prevent nitration of the organics in the acid dissolver. The technologies under consideration are: screening, sedimentation, elutriation. The recommended approach is to first screen the Sludge and resin 300 microns then subject the 300 microns plus material to elutriation.

  14. Integrated optic broadband duplexer made by ion exchange

    NASA Astrophysics Data System (ADS)

    Ghibaudo, E.; Broquin, J.-E.; Benech, P.

    2003-02-01

    The development of optical amplification and bidirectional traffic in local and wide area networks requires broadband multiplexers which are able to treat the signal of an entire telecommunication window. A device made by ion exchange and answering to these needs is proposed in this letter. Its working principle, based on a leaky structure is first explained. An experimental result confirming a good broadband spectral behavior is then presented. Its spectral response displays two duplexing bands of at least 100 nm.

  15. Ion exchange and adsorption on low rank coals for liquefaction

    SciTech Connect

    Vorres, K.S.

    1995-08-01

    The objectives of this program involve the study of the catalysis of liquefaction of low rank coals. Ion exchange and adsorption techniques are being used or modified to incorporate catalytically active metals into coal samples. Relative oil yields will be determined by Sandia National Laboratory and PETC collaborators to establish the effectiveness of the catalyst incorporation techniques. This report describes work done over the past 12 months of an on-going project.

  16. Water Exchange Rates and Molecular Mechanism around Aqueous Halide Ions

    SciTech Connect

    Annapureddy, Harsha V.; Dang, Liem X.

    2014-07-17

    Molecular dynamics simulations were performed to systematically study the water-exchange mechanism around aqueous chloride, bromide, and iodide ions. Transition state theory, Grote-Hynes theory, and the reactive flux method were employed to compute water exchange rates. We computed the pressure dependence of rate constants and the corresponding activation volumes to investigate the mechanism of the solvent exchange event. The activation volumes obtained using the transition state theory rate constants are negative for all the three anions, thus indicating an associative mechanism. Contrary to the transition state theory results, activation volumes obtained using rate constants from Grote-Hynes theory and the reactive flux method are positive, thus indicating a dissociative mechanism. The Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences (BES), of the U.S. Department of Energy (DOE) funded this work. Battelle operates Pacific Northwest National Laboratory for DOE. The calculations were carried out using computer resources provided by BES.

  17. Thermal analysis for ion-exchange column system

    SciTech Connect

    Lee, S. Y.; King, W. D.

    2012-07-01

    Models have been developed to simulate the thermal characteristics of Crystalline Silico-titanate (CST) ion exchange media fully loaded with radioactive cesium in a column configuration and distributed within a waste storage tank. This work was conducted to support the Small Column Ion Exchange (SCIX) program which is focused on processing dissolved, high-sodium salt waste for the removal of specific radionuclides (including Cs-137, Sr-90, and actinides) within a High Level Waste (HLW) storage tank at the Savannah River Site. A two-dimensional computational modeling approach for the in-column ion-exchange domain was taken to include conservative, bounding estimates for key parameters such that the results would provide the maximum centerline temperatures achievable under the design configurations using a feed composition known to promote high cesium loading on CST. A primary objective of these calculations was to estimate temperature distributions across packed CST beds immersed in waste supernate or filled with dry air under various accident scenarios. Accident scenarios evaluated included loss of salt solution flow through the bed, inadvertent column drainage, and loss of active cooling in the column. The modeling results demonstrate that the baseline design using one central and four outer cooling tubes provides a highly efficient cooling mechanism for reducing the maximum column temperature. (authors)

  18. Separation of phycocyanin from Spirulina platensis using ion exchange chromatography.

    PubMed

    Silveira, Silvana Terra; Quines, Luci Kelin de Menezes; Burkert, Carlos André Veiga; Kalil, Susana Juliano

    2008-08-01

    This paper presents the evaluation of some important parameters for the purification of phycocyanin using ion exchange chromatography. The influences of pH and temperature on the equilibrium partition coefficient were investigated to establish the best conditions for phycocyanin adsorption. The equilibrium isotherm for the phycocyanin-resin system was also determined. The separation of phycocyanin using the Q-Sepharose ion exchange resin was evaluated in terms of the pH and elution volume that improved the increase in purity and recovery. The highest partition coefficients were obtained in the pH range from 7.5 to 8.0 at 25 degrees C. Under these conditions the equilibrium isotherm for phycocyanin adsorption was well described by the Langmuir model, attaining a Q (m) of 22.7 mg/mL and K (d) of 3.1 x 10(-2) mg/mL. The best conditions for phycocyanin purification using the ion exchange column were at pH 7.5 with an elution volume of 36 mL, obtaining 77.3% recovery and a 3.4-fold increase in purity.

  19. Ion exchange extraction of heavy metals from wastewater sludges.

    PubMed

    Al-Enezi, G; Hamoda, M F; Fawzi, N

    2004-01-01

    Heavy metals are common contaminants of some industrial wastewater. They find their way to municipal wastewaters due to industrial discharges into the sewerage system or through household chemicals. The most common heavy metals found in wastewaters are lead, copper, nickel, cadmium, zinc, mercury, arsenic, and chromium. Such metals are toxic and pose serious threats to the environment and public health. In recent years, the ion exchange process has been increasingly used for the removal of heavy metals or the recovery of precious metals. It is a versatile separation process with the potential for broad applications in the water and wastewater treatment field. This article summarizes the results obtained from a laboratory study on the removal of heavy metals from municipal wastewater sludges obtained from Ardhiya plant in Kuwait. Data on heavy metal content of the wastewater and sludge samples collected from the plant are presented. The results obtained from laboratory experiments using a commercially available ion exchange resin to remove heavy metals from sludge were discussed. A technique was developed to solubilize such heavy metals from the sludge for subsequent treatment by the ion exchange process. The results showed high efficiency of extraction, almost 99.9%, of heavy metals in the concentration range bound in wastewater effluents and sludges. Selective removal of heavy metals from a contaminated wastewater/sludge combines the benefits of being economically prudent and providing the possibility of reuse/recycle of the treated wastewater effluents and sludges.

  20. Kinetic energy offsets for multicharged ions from an electron beam ion source.

    PubMed

    Kulkarni, D D; Ahl, C D; Shore, A M; Miller, A J; Harriss, J E; Sosolik, C E; Marler, J P

    2017-08-01

    Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar(4+) and Ar(8+) ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.

  1. Kinetic energy offsets for multicharged ions from an electron beam ion source

    NASA Astrophysics Data System (ADS)

    Kulkarni, D. D.; Ahl, C. D.; Shore, A. M.; Miller, A. J.; Harriss, J. E.; Sosolik, C. E.; Marler, J. P.

    2017-08-01

    Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar4+ and Ar8+ ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.

  2. Design of high efficiency fibers for ion exchange and heavy metal removal

    NASA Astrophysics Data System (ADS)

    Dominguez, Lourdes

    Ion exchange materials coated on glass fiber substrates have a number of advantages over the conventional ion exchange beads. These include simplification of the overall synthesis including faster more efficient functionalization and elimination of toxic solvents. Other benefits include the ability to be fabricated in the form of felts, papers, or fabrics, improving media contact efficiency and enhancing both the rates of reaction and regeneration. In addition, physical and mechanical requirements of strength and dimensional stability are achieved by use of glass fiber substrates. Investigations were focused on design of: (1) polymeric cationic exchange fibers and their application for lead and mercury removal, (2) polymeric anionic exchange fibers and their application for arsenate removal, (3) enhancement of anionic fiber selectivity for monovalent ions over divalent ions through bulkier triaklylamine functional groups, and (4) polymeric mercaptyl fibers for the application of arsenite removal. The design and characterization of a cationic exchange fiber is described. Dynamic mode (breakthrough) experiments for calcium, lead, and mercury ion solutions are also presented. The second system consists of the preparation and characterization of anionic exchange fibers with equilibrium adsorption isotherms and dynamic mode kinetic experiments for arsenate removal. Modification of the resin with bulkier functional groups (trimethylamine, triethylamine, tripropylamine, tributylanmine), thereby effecting a change in the selectivity from divalent species to monovalent species, is considered in the separation of nitrates from sulfates. The ability of a thiol group to bind to the highly toxic arsenite ion (as is done in proteins and enzymes) provided the model used to chemically modify and characterize a polyvinyl alcohol mercaptyl fibrous system, coated on a fiberglass substrate, for the purpose of arsenite (As3+) removal from water. Physical/chemical aspects of naturally

  3. Kinetic aspects of ion transport through neural membrane

    NASA Astrophysics Data System (ADS)

    Clay, John R.; Shlesinger, Michael F.

    1984-02-01

    The Hodgkin-Huxley model for the nerve membrane action potential is reviewed. The model can be described in terms of channels and gates. That is, ions permeate the nerve membrane through narrow ion specific pores, or channels, which are modulated by a voltage dependent gating process. The Hodgkin-Huxley model provides a detailed kinetic scheme for channel gating, but not for channel permeation. Radioactive tracer flux experiments suggest that permeation occurs via single file motion of ions through a channel. We have modeled this process as a random walk with internal states. The theory leads to expressions for one way fluxes which can be compared with experimental tracer flux data. Recent experiments on channel gating have indicated that the Hodgkin-Huxley model of the gating process requires certain modifications. We present a class of modifications involving temporal memory of gating and interactions between gating particles of any single channel. Thses models can also be described in terms of random walks.

  4. Modeling batch kinetics and thermodynamics of zinc and cadmium ions removal from waste solutions using synthetic zeolite A.

    PubMed

    El-Kamash, A M; Zaki, A A; El Geleel, M Abed

    2005-12-09

    The sorptive removal of zinc and cadmium ions from aqueous solutions using synthetic zeolite A was investigated. Experiments were carried out as a function of solute concentration and temperature (298-333 K). Several kinetic models were used to test the experimental rate data and to examine the controlling mechanism of the sorption process. Various parameters such as effective diffusion coefficient, activation energy and entropy of activation were evaluated. Equilibrium sorption data were analyzed using Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Of the model tested, both Freundlich and D-R isotherm expressions were found to give better fit to the experimental equilibrium data compared to Langmuir model. The mean free energy is in all cases in the range corresponding to the ion exchange type of sorption. The results indicated that synthetic zeolite A can be used as an efficient ion exchange material for the removal of zinc and cadmium ions from industrial and radioactive wastewaters.

  5. Statistical rate theory and kinetic energy-resolved ion chemistry: theory and applications.

    PubMed

    Armentrout, P B; Ervin, Kent M; Rodgers, M T

    2008-10-16

    Ion chemistry, first discovered 100 years ago, has profitably been coupled with statistical rate theories, developed about 80 years ago and refined since. In this overview, the application of statistical rate theory to the analysis of kinetic-energy-dependent collision-induced dissociation (CID) reactions is reviewed. This procedure accounts for and quantifies the kinetic shifts that are observed as systems increase in size. The statistical approach developed allows straightforward extension to systems undergoing competitive or sequential dissociations. Such methods can also be applied to the reverse of the CID process, association reactions, as well as to quantitative analysis of ligand exchange processes. Examples of each of these types of reactions are provided and the literature surveyed for successful applications of this statistical approach to provide quantitative thermochemical information. Such applications include metal-ligand complexes, metal clusters, proton-bound complexes, organic intermediates, biological systems, saturated organometallic complexes, and hydrated and solvated species.

  6. Characterization of poly(allylamine) as a polymeric ligand for ion-exchange protein chromatography.

    PubMed

    Li, Ming; Li, Yanying; Yu, Linling; Sun, Yan

    2017-02-24

    This work reports poly(allylamine) (PAA), as a polymeric ion-exchange ligand for protein chromatography. Sepharose FF was modified with PAA, and six anion exchangers with ionic capacities (ICs) from 165 to 618mmol/L were prepared. Inverse size exclusion chromatography, adsorption equilibrium, uptake kinetics and column elution were performed. It was found that both the adsorption capacity and effective diffusivity maintained low values in the IC range of 165-373mmol/L, but they started to increase beyond 373mmol/L, and increased by 80% and 23 times, respectively, when the IC reached 618mmol/L. Interestingly, a drastic decrease of pore size was observed around the IC of 373mmol/L. The results suggest that the PAA chains played an important role in protein adsorption by altering the inner pore structure of the gels. It is considered that, PAA chains turn from inextensible states with multipoint-grafting on the pore surface at low coupling densities (IC<373mmol/L) to closer, extended and flexible grafting states with less coupling points at higher coupling densities (IC>373mmol/L). These characters of the grafted chains at higher IC values benefit in protein adsorption by three-dimensional binding and encouraged the happening of "chain delivery" of bound proteins on the chains. Besides, the ion exchangers showed favorable adsorption and uptake properties in a wide ionic strength range, 0-500mmol/L NaCl, indicating much better salt tolerance feature than the so-far reported ion exchangers. Moreover, a mild condition of pH 5.0 offered effective recovery of bound proteins in elution chromatography. The results indicate that the PAA-based anion exchanger of a high IC value is promising for high-capacity protein chromatography dealing with feedstock of a wide range of ionic strengths.

  7. Storage and Aging Effects on Spherical Resorcinol-Formaldehyde Resin Ion Exchange Performance

    SciTech Connect

    Fiskum, Sandra K.; Arm, Stuart T.; Edwards, Matthew K.; Steele, Marilyn J.; Thomas, Kathie K.

    2007-09-10

    Bechtel National, Inc. (BNI) is evaluating the alternate Cs ion exchanger, spherical resorcinol-formaldehyde (RF), for use in the River Protection Project-Waste Treatment Plant (RPP-WTP).( ) Previous test activities with spherical RF indicate that it has adequate capacity, selectivity, and kinetics to perform in the plant according to the flowsheet needs. It appears to have better elution and hydraulic properties than the existing alternatives: ground-gel RF and SuperLig® 644 (SL 644).( ) To date, the spherical RF performance testing has been conducted on freshly manufactured resin (within ~2 months of manufacture). The ion exchange resins will be manufactured and shipped to the WTP up to 1 year before being used in the plant. Changes in the resin properties during storage could reduce the capacity of the resin to remove Cs from low-activity waste solutions. Active sites on organic SL-644 resin have been shown to degrade during storage (Arm et al. 2004). Additional testing was needed to study the effects of storage conditions and aging on spherical RF ion exchange performance. Variables that could have a significant impact on ion exchange resins during storage include storage temperature, medium, and time. Battelle—Pacific Northwest Division (PNWD) was contracted to test the effects of various storage conditions on spherical RF resin. Data obtained from the testing will be used by the WTP operations to provide direction for suitable storage conditions and manage the spherical RF resin stock. Storage test conditions included wet and dry resin configurations under nitrogen at three temperatures. Work was initially conducted under contract number 24590-101-TSA-W000-00004 satisfying the needs defined in Appendix C of the Research and Technology Plan( ) TSS A-219 to evaluate the impact of storage conditions on RF resin performance. In February 2007, the contract mechanism was switched to Pacific Northwest National Laboratory (PNNL) Operating Contract DE-AC05-76RL

  8. Kinetic and Mechanistic Studies of the Deuterium Exchange in Classical Keto-Enol Tautomeric Equilibrium Reactions

    ERIC Educational Resources Information Center

    Nichols, Michael A.; Waner, Mark J.

    2010-01-01

    An extension of the classic keto-enol tautomerization of beta-dicarbonyl compounds into a kinetic analysis of deuterium exchange is presented. It is shown that acetylacetone and ethyl acetoacetate undergo nearly complete deuterium exchange of the alpha-methylene carbon when dissolved in methanol-d[subscript 4]. The extent of deuteration may be…

  9. Kinetic and Mechanistic Studies of the Deuterium Exchange in Classical Keto-Enol Tautomeric Equilibrium Reactions

    ERIC Educational Resources Information Center

    Nichols, Michael A.; Waner, Mark J.

    2010-01-01

    An extension of the classic keto-enol tautomerization of beta-dicarbonyl compounds into a kinetic analysis of deuterium exchange is presented. It is shown that acetylacetone and ethyl acetoacetate undergo nearly complete deuterium exchange of the alpha-methylene carbon when dissolved in methanol-d[subscript 4]. The extent of deuteration may be…

  10. Measuring a hidden coordinate: Rate-exchange kinetics from 3D correlation functions.

    PubMed

    Berg, Mark A; Darvin, Jason R

    2016-08-07

    Nonexponential kinetics imply the existence of at least one slow variable other than the observable, that is, the system has a "hidden" coordinate. We develop a simple, but general, model that allows multidimensional correlation functions to be calculated for these systems. Homogeneous and heterogeneous mechanisms are both included, and slow exchange of the rates is allowed. This model shows that 2D and 3D correlation functions of the observable measure the distribution and kinetics of the hidden coordinate controlling the rate exchange. Both the mean exchange time and the shape of the exchange relaxation are measurable. However, complications arise because higher correlation functions are sums of multiple "pathways," each of which measures different dynamics. Only one 3D pathway involves exchange dynamics. Care must be used to extract exchange dynamics without contamination from other processes.

  11. PARAFAC analysis of IBIL spectra from silver ion exchanged glasses

    NASA Astrophysics Data System (ADS)

    Valotto, G.; Cattaruzza, E.; Mardegan, M.; Quaranta, A.

    2017-01-01

    In this work we present for the first time an application of PARAllel FACtor (PARAFAC) analysis to the investigation of Ion Beam Induced Luminescence (IBIL) spectra of Ag+ ↔ Na+ ion exchanged silicate glasses, in order to check the possibility to obtain additional information on the formation of silver aggregates under ion irradiation by a proper statistical rearrangement of experimental spectra. We decomposed the data by PARAFAC taking into account both IBIL emission features and their evolution as a function of the time. Shape and trend under irradiation of the extracted components were correlated to silver concentration and aggregates in the investigated systems. Strength and weakness of this statistical approach applied to IBIL spectra recorded as a function of time were evidenced and discussed.

  12. Dipole-Potential-Mediated Effects on Ion Pump Kinetics

    PubMed Central

    Clarke, Ronald J.

    2015-01-01

    The kinetics of conformational changes of P-type ATPases necessary for the occlusion or deocclusion of transported ions are known to be sensitive to the composition of the surrounding membrane, e.g., phospholipid content, mole percentage of cholesterol, and the presence of lipid-bound anions. Research has shown that many membrane components modify the dipole potential of the lipid head-group region. Based on the observation that occlusion/deocclusion reactions of ion pumps perturb the membrane surrounding the protein, a mechanism is suggested whereby dipole potential modifiers induce preferential stabilization or destabilization of occluded or nonoccluded states of the protein, leading to changes in the forward and backward rate constants for the transition. The mechanism relies on the assumption that conformational changes of the protein are associated with changes in its hydrophobic thickness that requires a change in local lipid packing density to allow hydrophobic matching with the membrane. The changes in lipid packing density cause changes in local lipid dipole potential that are responsible for the dependence of conformational kinetics on dipole potential modifiers. The proposed mechanism has the potential to explain effects of lipid composition on the kinetics of any membrane protein undergoing significant changes in its membrane cross-sectional area during its activity. PMID:26488640

  13. Donnan dialysis with ion-exchange membranes. 3: Diffusion coefficients using ions of different valence

    SciTech Connect

    Miyoshi, Hirofumi

    1999-01-01

    Donnan dialysis with ion-exchange membranes was studied under various kinds of experimental conditions using ions of different valences. The diffusion coefficients (D{sub d}) of various kinds of ions in the ion-exchange membrane were obtained by curve fitting an equation derived from the mass balance to three kinds of Donnan dialytic experiments. It was found that the value of D{sub d}/D{sub s} using D{sub d} of monovalent ions in Donnan dialysis with a set of monovalent feed ions and bivalent driving ions was 1/175, where D{sub s} represents a diffusion coefficient in solution. D{sub s} was calculated from the Nernst-Einstein equation substituted by the ionic conductance of ions at infinite dilution in water. Using D{sub d} of bivalent ions in Donnan dialysis with the same set led to a D{sub d}/D{sub s} value of 1/438. Moreover, using D{sub d} in Donnan dialysis with the same set, the value of D{sub d}/D{sub e} was kept constant at 0.4 (D{sub e} expresses the diffusion coefficient in the membrane when the valences of the feed and driving ions are equal). On the other hand, both D{sub d}/D{sub s} and D{sub d}/D{sub e} using D{sub d} in Donnan dialysis with a set of bivalent feed ions and monovalent driving ions were not constant.

  14. Design and comparison of exchange spectroscopy approaches to cryptophane-xenon host-guest kinetics.

    PubMed

    Korchak, Sergey; Kilian, Wolfgang; Schröder, Leif; Mitschang, Lorenz

    2016-04-01

    Exchange spectroscopy is used in combination with a variation of xenon concentration to disentangle the kinetics of the reversible binding of xenon to cryptophane-A. The signal intensity of either free or crytophane-bound xenon decays in a manner characteristic of the underlying exchange reactions when the spins in the other pool are perturbed. Three experimental approaches, including the well-known Hyper-CEST method, are shown to effectively entail a simple linear dependence of the signal depletion rate, or of a related quantity, on free xenon concentration. This occurs when using spin pool saturation or inversion followed by free exchange. The identification and quantification of contributions to the binding kinetics is then straightforward: in the depletion rate plot, the intercept at the vanishing free xenon concentration represents the kinetic rate coefficient for xenon detachment from the host by dissociative processes while the slope is indicative of the kinetic rate coefficient for degenerate exchange reactions. Comparing quantified kinetic rates for hyperpolarized xenon in aqueous solution reveals the high accuracy of each approach but also shows differences in the precision of the numerical results and in the requirements for prior knowledge. Because of their broad range of applicability the proposed exchange spectroscopy experiments can be readily used to unravel the kinetics of complex formation of xenon with host molecules in the various situations appearing in practice.

  15. Reconstruction of Cell Surface Densities of Ion Pumps, Exchangers, and Channels from mRNA Expression, Conductance Kinetics, Whole-Cell Calcium, and Current-Clamp Voltage Recordings, with an Application to Human Uterine Smooth Muscle Cells

    PubMed Central

    Atia, Jolene; McCloskey, Conor; Shmygol, Anatoly S.; Rand, David A.; van den Berg, Hugo A.; Blanks, Andrew M.

    2016-01-01

    Uterine smooth muscle cells remain quiescent throughout most of gestation, only generating spontaneous action potentials immediately prior to, and during, labor. This study presents a method that combines transcriptomics with biophysical recordings to characterise the conductance repertoire of these cells, the ‘conductance repertoire’ being the total complement of ion channels and transporters expressed by an electrically active cell. Transcriptomic analysis provides a set of potential electrogenic entities, of which the conductance repertoire is a subset. Each entity within the conductance repertoire was modeled independently and its gating parameter values were fixed using the available biophysical data. The only remaining free parameters were the surface densities for each entity. We characterise the space of combinations of surface densities (density vectors) consistent with experimentally observed membrane potential and calcium waveforms. This yields insights on the functional redundancy of the system as well as its behavioral versatility. Our approach couples high-throughput transcriptomic data with physiological behaviors in health and disease, and provides a formal method to link genotype to phenotype in excitable systems. We accurately predict current densities and chart functional redundancy. For example, we find that to evoke the observed voltage waveform, the BK channel is functionally redundant whereas hERG is essential. Furthermore, our analysis suggests that activation of calcium-activated chloride conductances by intracellular calcium release is the key factor underlying spontaneous depolarisations. PMID:27105427

  16. Recent progress and applications of ion-exclusion/ion-exchange chromatography for simultaneous determination of inorganic anions and cations.

    PubMed

    Nakatani, Nobutake; Kozaki, Daisuke; Mori, Masanobu; Tanaka, Kazuhiko

    2012-01-01

    One of the ultimate goals of ion chromatography is to determine both anions and cations found in samples with a single chromatographic run. In the present article, recent progress in ion-exclusion/ion-exchange chromatography for the simultaneous determinations of inorganic anions and cations are reviewed. Firstly, the principle and the control for the simultaneous separation and detection of analyte ions using ion-exclusion/cation-exchange chromatography with a weakly acidic cation-exchange column are outlined. Then, advanced chromatographic techniques in terms of analytical time, selectively and sensitivity are summarized. As a related method, ion-exclusion/anion-exchange chromatography with an anion-exchange column could be used for the simultaneous determination of inorganic nitrogen species, such as ammonium, nitrite and nitrate ions. Their usefulness and applications to water-quality monitoring and related techniques are also described.

  17. Ion specificity in α-helical folding kinetics.

    PubMed

    von Hansen, Yann; Kalcher, Immanuel; Dzubiella, Joachim

    2010-11-04

    The influence of the salts KCl, NaCl, and NaI at molar concentrations on the α-helical folding kinetics of the alanine-based oligopeptide Ace-AEAAAKEAAAKA-Nme is investigated by means of (explicit-water) molecular dynamics simulations and a diffusional analysis. The mean first passage times for folding and unfolding are found to be highly salt-specific. In particular, the folding times increase about 1 order of magnitude for the sodium salts. The drastic slowing can be traced to long-lived, compact configurations of the partially folded peptide, in which sodium ions are tightly bound by several carbonyl and carboxylate groups. This multiple trapping leads to a nonexponential residence time distribution of the cations in the first solvation shell of the peptide. The analysis of α-helical folding in the framework of diffusion in a reduced (one-dimensional) free energy landscape further shows that the salt not only specifically modifies equilibrium properties but also induces kinetic barriers due to individual ion binding. In the sodium salts, for instance, the peptide's configurational mobility (or "diffusivity") can decrease about 1 order of magnitude. This study demonstrates the highly specific action of ions and highlights the intimate coupling of intramolecular friction and solvent effects in protein folding.

  18. Kinetic Theory Model for Ion Movement through Biological Membranes

    PubMed Central

    Mackey, Michael C.

    1971-01-01

    A model for ion movement through specialized sites in the plasma membrane is presented and analyzed using techniques from nonequilibrium kinetic theory. It is assumed that ions traversing these specialized regions interact with membrane molecules through central conservative forces. The membrane molecules are approximated as massive spherical scattering centers so that ionic fractional energy losses per collision are much less than one. Equations for steady-state membrane ionic currents and conductances as functions of externally applied electric field strength are derived and numerically analyzed, under the restriction of identical solutions on each size of the membrane and constant electric fields within the membrane. The analysis is carried through for a number of idealized ion-membrane molecule central force interactions. For any interaction leading to a velocity-dependent ion-membrane molecule collision frequency, the membrane chord conductance is a function of the externally applied electric field. Interactions leading to a collision frequency that is an increasing (decreasing) function of ionic velocity are characterized by chord conductances that are decreasing (increasing) functions of field strength. For ion-neutral molecule interactions, the conductance is such a rapidly decreasing function of field strength that the slope conductance becomes negative for all field strengths above a certain value. PMID:5539001

  19. Exam Question Exchange: A Popular Approach to Reaction Kinetics.

    ERIC Educational Resources Information Center

    Collins, Michael P. S.; Alexander, John J., Ed.

    1979-01-01

    Presents an undergraduate physical chemistry question and its acceptable solution. This question, presented to share exam questions with other teachers, shows the analogy between molecular kinetics and population dynamics. (HM)

  20. Exam Question Exchange: A Popular Approach to Reaction Kinetics.

    ERIC Educational Resources Information Center

    Collins, Michael P. S.; Alexander, John J., Ed.

    1979-01-01

    Presents an undergraduate physical chemistry question and its acceptable solution. This question, presented to share exam questions with other teachers, shows the analogy between molecular kinetics and population dynamics. (HM)

  1. Structural Insight into the Ion-Exchange Mechanism of the Sodium/Calcium Exchanger

    SciTech Connect

    Liao, Jun; Li, Hua; Zeng, Weizhong; Sauer, David B.; Belmares, Ricardo; Jiang, Youxing

    2012-06-19

    Sodium/calcium (Na{sup +}/Ca{sup 2+}) exchangers (NCX) are membrane transporters that play an essential role in maintaining the homeostasis of cytosolic Ca{sup 2+} for cell signaling. We demonstrated the Na{sup +}/Ca{sup 2+}-exchange function of an NCX from Methanococcus jannaschii (NCX{_}Mj) and report its 1.9 angstrom crystal structure in an outward-facing conformation. Containing 10 transmembrane helices, the two halves of NCX{_}Mj share a similar structure with opposite orientation. Four ion-binding sites cluster at the center of the protein: one specific for Ca{sup 2+} and three that likely bind Na{sup +}. Two passageways allow for Na{sup +} and Ca{sup 2+} access to the central ion-binding sites from the extracellular side. Based on the symmetry of NCX{_}Mj and its ability to catalyze bidirectional ion-exchange reactions, we propose a structure model for the inward-facing NCX{_}Mj.

  2. Continuous ion exchange separation of zirconium and hafnium

    SciTech Connect

    Begovich, J.M.; Sisson, W.G.

    1981-01-01

    A pressurized continuous annular chromatograph (CAC) has been developed for truly continuous ion exchange preparative separations. This device utilizes a slowly rotating annular bed of sorbent material, fixed multiple feed points, and fixed withdrawal locations. Most of our investigations have been performed with a 28-cm-diam by 60-cm-long CAC, but a larger model has recently been designed and constructed. A detailed study has been made of the separation of copper, nickel, and cobalt components from a simulated carbonate leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Recent studies have investigated the ion exchange separation of zirconium and hafnium from a sulfate feed solution. Nuclear reactor-grade zirconium, containing < 0.01 wt % hafnium, and hafnium, containing < 1% zirconium, have been continuously prepared using cation exchange resin in the pressurized CAC. This device, because of its continuous feed and product withdrawal, its adaptability to largescale operations, and its ability to separate many components, is expected to make chromatography a more competitive process in the industrial sector.

  3. Fully kinetic simulation study of ion-acoustic solitons in the presence of trapped electrons.

    PubMed

    Hosseini Jenab, S M; Spanier, F

    2017-05-01

    The nonlinear fluid theory developed by Schamel suggests a modified KdV equation to describe the temporal evolution of ion acoustic (IA) solitons in the presence of trapped electrons. The validity of this theory is studied here by verifying solitons' main characteristic, i.e., stability against successive mutual collisions. We have employed a kinetic model as a more comprehensive theory than the fluid one, and utilized a fully kinetic simulation approach (both ions and electrons are treated based on the Vlasov equation). In the simulation approach, these solitons are excited self-consistently by employing the nonlinear process of IA solitons formation from an initial density perturbation (IDP). The effect of the size of IDPs on the chain formation is proved by the simulation code as a benchmark test. It is shown that the IA solitons, in the presence of trapped electrons, can retain their features (both in spatial and velocity direction) after successive mutual collisions. The collisions here include encounters of IA solitons with the same trapping parameter, while differing in size. Kinetic simulation results reveal a complicated behavior during a collision between IA solitons in contrast to the fluid theory predictions and simulations. In the range of parameters considered here, two oppositely propagating solitons rotate around their collective center in the phase space during a collision, independent of their trapping parameters. Furthermore, they exchange some portions of their trapped populations.

  4. Fully kinetic simulation study of ion-acoustic solitons in the presence of trapped electrons

    NASA Astrophysics Data System (ADS)

    Hosseini Jenab, S. M.; Spanier, F.

    2017-05-01

    The nonlinear fluid theory developed by Schamel suggests a modified KdV equation to describe the temporal evolution of ion acoustic (IA) solitons in the presence of trapped electrons. The validity of this theory is studied here by verifying solitons' main characteristic, i.e., stability against successive mutual collisions. We have employed a kinetic model as a more comprehensive theory than the fluid one, and utilized a fully kinetic simulation approach (both ions and electrons are treated based on the Vlasov equation). In the simulation approach, these solitons are excited self-consistently by employing the nonlinear process of IA solitons formation from an initial density perturbation (IDP). The effect of the size of IDPs on the chain formation is proved by the simulation code as a benchmark test. It is shown that the IA solitons, in the presence of trapped electrons, can retain their features (both in spatial and velocity direction) after successive mutual collisions. The collisions here include encounters of IA solitons with the same trapping parameter, while differing in size. Kinetic simulation results reveal a complicated behavior during a collision between IA solitons in contrast to the fluid theory predictions and simulations. In the range of parameters considered here, two oppositely propagating solitons rotate around their collective center in the phase space during a collision, independent of their trapping parameters. Furthermore, they exchange some portions of their trapped populations.

  5. Kinetic and thermodynamic evaluation of phosphate ions binding onto sevelamer hydrochloride.

    PubMed

    Elsiddig, Reem; Hughes, Helen; Owens, Eleanor; O' Reilly, Niall J; O'Grady, David; McLoughlin, Peter

    2014-10-20

    Sevelamer hydrochloride is the first non-aluminium, non-calcium-based phosphate binder developed for the management of hyperphosphatemia in end stage renal diseases. It is a synthetic ion-exchange polymer which binds and removes phosphate ions due to the high content of cationic charge associated with protonated amine groups on the polymer matrix. This is the first in-depth study investigating phosphate removal in vitro from aqueous solutions using commercially available sevelamer hydrochloride at physiological conditions of phosphate level, pH and temperature. The kinetic and thermodynamic parameters of phosphate binding onto the sevelamer hydrochloride particles were evaluated in order to define the binding process. A series of kinetic studies were carried out in order to delineate the effect of initial phosphate concentration, absorbent dose and temperature on the rate of binding. The results were analysed using three kinetic models with the best-fit of the experimental data obtained using a pseudo-second order model. Thermodynamic parameters provide in-depth information on inherent energetic changes that are associated with binding. Free energy ΔG°, enthalpy ΔH°, and entropy ΔS° changes were calculated in this study in order to assess the relationship of these parameters to polymer morphology. The binding reaction was found to be a spontaneous endothermic process with increasing entropy at the solid-liquid interface.

  6. Effects of Ion-Ion Collisions and Inhomogeneity in Two-Dimensional Kinetic Ion Simulations of Stimulated Brillouin Backscattering

    SciTech Connect

    Cohen, B I; Divol, L; Langdon, A B; Williams, E A

    2005-10-17

    Two-dimensional simulations with the BZOHAR [B.I. Cohen, B.F. Lasinski, A.B. Langdon, and E.A. Williams, Phys. Plasmas 4, 956 (1997)] hybrid code (kinetic particle ions and Boltzmann fluid electrons) have been used to investigate the saturation of stimulated Brillouin backscatter (SBBS) instability including the effects of ion-ion collisions and inhomogeneity. Ion-ion collisions tend to increase ion-wave dissipation, which decreases the gain exponent for stimulated Brillouin backscattering; and the peak Brillouin backscatter reflectivities tend to decrease with increasing collisionality in the simulations. Two types of Langevin-operator, ion-ion collision models were implemented in the simulations. In both models used the collisions are functions of the local ion temperature and density, but the collisions have no velocity dependence in the first model. In the second model, the collisions are also functions of the energy of the ion that is being scattered so as to represent a Fokker-Planck collision operator. Collisions decorrelate the ions from the acoustic waves in SBS, which disrupts ion trapping in the acoustic wave. Nevertheless, ion trapping leading to a hot ion tail and two-dimensional physics that allows the SBS ion waves to nonlinearly scatter remain robust saturation mechanisms for SBBS in a high-gain limit over a range of ion collisionality. SBS backscatter in the presence of a spatially nonuniform plasma flow is also investigated. Simulations show that depending on the sign of the spatial gradient of the flow relative to the backscatter, ion trapping effects that produce a nonlinear frequency shift can enhance (auto-resonance) or decrease (anti-auto-resonance) reflectivities in agreement with theoretical arguments.

  7. Treatment of chromium plating process effluents with ion exchange resins.

    PubMed

    Tenório, J A; Espinosa, D C

    2001-01-01

    The surface treatment industry deals with various heavy metals, including the elements Cr, Zn, Ni, Cd, and Cu. Conventional treatments of effluents generate class I solid residue. The aim of this investigation was to study the viability of ion exchange as an alternative process for treatment of rinse water and to determine the efficacy of two ion exchange systems, System 1: "strong" cationic resin-"strong" anionic resin and System 2: "strong" cationic resin-"weak" anionic resin. Commercial resins and solutions taken from rinse tanks of chromium plating companies were used in this investigation. A two-column system, one for the cationic resin and another for the anionic resin, both with 150 ml capacity was mounted. The solution was percolated at a rate of 10 ml/min. The following solutions were used for regeneration of the resins: 2% H2SO4 for the cationic and 4% NaOH for the anionic. The percolated solutions revealed chromium contents of less than 0.25 mg/l, independent of the system used. The "strong" cationic resin-"weak" anionic resin gave excellent regeneration results. The "strong" cationic-"strong" anionic resin presented problems during regeneration, and did not release the retained ions after percolation of 2000 ml of 4% NaOH solution. It is concluded that for this type of treatment, the system composed of "strong" cationic resin and "weak" anionic resin is more appropriate.

  8. Kinetic simulation of asymmetric magnetic reconnection with cold ions

    NASA Astrophysics Data System (ADS)

    Dargent, J.; Aunai, N.; Lavraud, B.; Toledo-Redondo, S.; Shay, M. A.; Cassak, P. A.; Malakit, K.

    2017-05-01

    At the dayside magnetopause, the magnetosphere often contains a cold ion population of ionospheric origin. This population is not always detectable by particle instruments due to its low energy, despite having an important contribution to the total ion density and therefore an impact on key plasma processes such as magnetic reconnection. The exact role and implications of this low-temperature population are still not well known and has not been addressed with numerical simulation before. We present 2-D fully kinetic simulations of asymmetric magnetic reconnection with and without a cold ion population on the magnetospheric side of the magnetopause, but sharing the same total density, temperature, and magnetic field profiles. The comparison of the simulations suggests that cold ions directly impact signatures recently suggested as a good marker of the X line region: the Larmor electric field. Our simulations reveal that this electric field, initially present all along the magnetospheric separatrix, is related to the bounce of magnetosheath ions at the magnetopause magnetic field reversal through Speiser-like orbits. Once reconnection widens the current sheet away from the X line, the bouncing stops and the electric field signature remains solely confined near the X line. When cold ions are present, however, their very low temperature enables them to E × B drift in the electric field structure. If their density is large enough compared to other ions, their contribution to the momentum equation is capable of maintaining the signature away from the X line. This effect must be taken into account when analyzing in situ spacecraft measurements.

  9. Characterization of magnetic ion-exchange composites for protein separation from biosuspensions.

    PubMed

    Käppler, Tobias E; Hickstein, Birgit; Peuker, Urs A; Posten, Clemens

    2008-06-01

    Downstream processing is a major issue in biotechnological production. A multitude of unit operations with nonsatisfying yield are often used to reach the desired product purity. Direct recovery technologies such as high-gradient magnetic fishing (HGMF) are advantageous because of their ability to separate the desired product in early stages from crude cultivation broths. However, the use of magnetic particles to capture valuable biotechnological products is often linked to the drawback that support particles are expensive and not available in greater quantities. This current work presents new composite magnetic particles that can be used in biotechnology. They are manufactured by a spray drying process. During this process, the nanosized magnetite particles as well as functional ion-exchange nanoparticles are integrated into one particle in which they are linked by a matrix polymer. The production procedure is flexible, scalable, and therefore economical. These particles have good adsorption capacities of up to 85 mg/g adsorbed protein and good binding kinetics. They are resistant to harsh conditions such as short ultrasonic treatment or extreme pHs. In order to test their usefulness in biosuspensions, model proteins were separated using these particles. The anion and cation exchanger particles separated lysozyme (LZ) or BSA from cultivation suspensions. The selectivity of recovery was dependent on other proteins present as is usual for ion-exchange binding mechanisms.

  10. Nitrate and Perchlorate removal from groundwater by ion exchange

    SciTech Connect

    Burge, S; Halden, R

    1999-09-15

    This study was conducted to evaluate the performance of a small scale ion exchange unit (Krudico, Inc of Auborn, IA) for removal of nitrate and perchlorate from groundwater at Lawrence Livermore National Laboratory's Site 300. The unit was able to treat 3,600 gallons of Site 300 groundwater, at an average influent concentration of 100 mg/L NO{sub 3}{sup -} before breakthrough occurred. The unit contained 2.5 ft{sup 3} of Sybron SR-7 resin. Seventy gallons of regeneration waste were generated (water treated to waste ratio of 51:1). The effluent concentration was about 20 mg/L NO{sub 3}{sup -}, which is equivalent to a treatment efficiency of at least 80%. There are several options for implementing this technology at Site 300. A target well, in the 817 area, has been selected. It has a 3 to 4 gpm flow rate, and concentrations of 90 mg/L NO{sub 3}{sup -} and 40 {micro}g/L perchlorate. The different treatment options include ion exchange treatment of nitrate only, nitrate and perchlorate, or perchlorate only. Option 1: For the treatment of nitrate only, this unit will be able to treat 3,700 gallons of water before regeneration is required. If both columns of the ion exchange unit are used, 7,400 gallons could be treated before the columns will need to be regenerated (producing 140 gallons of waste, per cycle or every 1.5 days). The effluent nitrate concentration is expected to be about 17 mg/L. Annual operation and maintenance costs are estimated to be $0.14 per gallon of water treated. Option 2: If only perchlorate is to be removed with ion exchange at the 817 area, a smaller unit should be considered. A 55 gallon canister filled with ion exchange resin should be able to reduce perchlorate concentrations in the groundwater from 40 {micro}g/L to non-detect levels for three years before the resin would need to be replaced. The contaminant-laden resin would be disposed of as hazardous waste. It is not practical to regenerate the resin because of the extreme difficulty of

  11. Ion-Exchange Chromatography: Basic Principles and Application.

    PubMed

    Cummins, Philip M; Rochfort, Keith D; O'Connor, Brendan F

    2017-01-01

    Ion-Exchange Chromatography (IEC) allows for the separation of ionizable molecules on the basis of differences in charge properties. Its large sample-handling capacity, broad applicability (particularly to proteins and enzymes), moderate cost, powerful resolving ability, and ease of scale-up and automation have led to it becoming one of the most versatile and widely used of all liquid chromatography (LC) techniques. In this chapter, we review the basic principles of IEC, as well as the broader criteria for selecting IEC conditions. By way of further illustration, we outline basic laboratory protocols to partially purify a soluble serine peptidase from bovine whole brain tissue, covering crude tissue extract preparation through to partial purification of the target enzyme using anion-exchange chromatography. Protocols for assaying total protein and enzyme activity in both pre- and post-IEC fractions are also described.

  12. Ion exchange and adsorption on low rank coals for liquefaction

    SciTech Connect

    Vorres, K.S.

    1994-09-01

    The objectives of this program are to study the application of catalysts and the catalysis of liquefaction of low rank coals. Ion exchange and adsorption techniques are being used or modified to incorporate catalytically active metals (Fe, Co, Ni and Mo) in relatively small (100-2000 ppM) quantities into coal samples. Relative oil yields are being determined by PETC and Auburn University workers as collaborators to establish the effectiveness of the catalyst incorporation techniques. It is hoped that these techniques will provide highly active forms of the catalyst in low concentrations to minimize the need for metals recovery. A two step preparation of the coal is used to (1) remove material which both limits oil conversion and prepares for the addition of exchangeable catalyst, and (2) add catalytically active material which enhances the conversion of the coal matter to the oil fraction in the processing.

  13. Ion-exchange equilibrium of N-acetyl-D-neuraminic acid on a strong anionic exchanger.

    PubMed

    Wu, Jinglan; Ke, Xu; Zhang, Xudong; Zhuang, Wei; Zhou, Jingwei; Ying, Hanjie

    2015-09-15

    N-acetyl-D-neuraminic acid (Neu5Ac) is a high value-added product widely applied in the food industry. A suitable equilibrium model is required for purification of Neu5Ac based on ion-exchange chromatography. Hence, the equilibrium uptake of Neu5Ac on a strong anion exchanger, AD-1 was investigated experimentally and theoretically. The uptake of Neu5Ac by the hydroxyl form of the resin occurred primarily by a stoichiometric exchange of Neu5Ac(-) and OH(-). The experimental data showed that the selectivity coefficient for the exchange of Neu5Ac(-) with OH(-) was a non-constant quantity. Subsequently, the Saunders' model, which took into account the dissociation reactions of Neu5Ac and the condition of electroneutrality, was used to correlate the Neu5Ac sorption isotherms at various solution pHs and Neu5Ac concentrations. The model provided an excellent fit to the binary exchange data for Cl(-)/OH(-) and Neu5Ac(-)/OH(-), and an approximate prediction of equilibrium in the ternary system Cl(-)/Neu5Ac(-)/OH(-). This basic information combined with the general mass transfer model could lay the foundation for the prediction of dynamic behavior of fixed bed separation process afterwards.

  14. Spectator Ions ARE Important! A Kinetic Study of the Copper-Aluminum Displacement Reaction

    ERIC Educational Resources Information Center

    Sobel, Sabrina G.; Cohen, Skyler

    2010-01-01

    Surprisingly, spectator ions are responsible for unexpected kinetics in the biphasic copper(II)-aluminum displacement reaction, with the rate of reaction dependent on the identity of the otherwise ignored spectator ions. Application of a published kinetic analysis developed for a reaction between a rotating Al disk and a Cu(II) ion solution to the…

  15. Spectator Ions ARE Important! A Kinetic Study of the Copper-Aluminum Displacement Reaction

    ERIC Educational Resources Information Center

    Sobel, Sabrina G.; Cohen, Skyler

    2010-01-01

    Surprisingly, spectator ions are responsible for unexpected kinetics in the biphasic copper(II)-aluminum displacement reaction, with the rate of reaction dependent on the identity of the otherwise ignored spectator ions. Application of a published kinetic analysis developed for a reaction between a rotating Al disk and a Cu(II) ion solution to the…

  16. Kinetic models of sub-ion cylindrical magnetic hole

    NASA Astrophysics Data System (ADS)

    Shustov, P. I.; Artemyev, A. V.; Vasko, I. Y.; Yushkov, E. V.

    2016-12-01

    Magnetic holes are magnetoplasma structures very similar to the classical θ-pinch. They are widely observed in the space plasma and identified by the substantial magnetic field depressions on scales from magnetohydrodynamic range to electron scales. In this paper, we develop the kinetic models of cylindrically symmetric magnetic holes with sub-ion scales using two types of charged particle distribution functions (both current-carrying and background plasma populations are included). We demonstrate that developed magnetic holes have configurations very similar to those revealed in the recent spacecraft observations in the Earth magnetosphere: both localized electron currents and strong radial electric fields are found at the magnetic hole boundary. We demonstrate that for realistic plasma parameters, the inclusion of ion currents into the model produces magnetic holes with double-scale magnetic field profile. We find that the magnetic hole depth (amplitude of the magnetic field depression) depends on the magnetic hole typical radius. Possible applications of developed models are discussed.

  17. HEAT TRANSFER ANALYSIS FOR ION-EXCHANGE COLUMN SYSTEM

    SciTech Connect

    Lee, S.; King, W.

    2011-05-23

    Models have been developed to simulate the thermal characteristics of Crystalline Silicotitanate (CST) ion exchange media fully loaded with radioactive cesium in a column configuration and distributed within a waste storage tank. This work was conducted to support the Small Column Ion Exchange (SCIX) program which is focused on processing dissolved, high-sodium salt waste for the removal of specific radionuclides (including Cs-137, Sr-90, and actinides) within a High Level Waste (HLW) storage tank at the Savannah River Site. The SCIX design includes CST columns inserted and supported in the tank top risers for cesium removal. Temperature distributions and maximum temperatures across the column were calculated with a focus on process upset conditions. A two-dimensional computational modeling approach for the in-column ion-exchange domain was taken to include conservative, bounding estimates for key parameters such that the results would provide the maximum centerline temperatures achievable under the design configurations using a feed composition known to promote high cesium loading on CST. The current full-scale design for the CST column includes one central cooling pipe and four outer cooling tubes. Most calculations assumed that the fluid within the column was stagnant (i.e. no buoyancy-induced flow) for a conservative estimate. A primary objective of these calculations was to estimate temperature distributions across packed CST beds immersed in waste supernate or filled with dry air under various accident scenarios. Accident scenarios evaluated included loss of salt solution flow through the bed, inadvertent column drainage, and loss of active cooling in the column. The modeling results demonstrate that the baseline design using one central and four outer cooling tubes provides a highly efficient cooling mechanism for reducing the maximum column temperature.

  18. The modification of ion exchange heterogeneous catalysts for biodiesel synthesis

    NASA Astrophysics Data System (ADS)

    Hartono, R.; Mulia, B.; Sahlan, M.; Utami, T. S.; Wijanarko, Anondho; Hermansyah, Heri

    2017-03-01

    Conventionally, biodiesel is produced by using the homogeneous catalyst which has difficulty in high cost of the separation process. The heterogeneous catalysts ion exchange resin by its Solid phase can make an easier separation process, able to be reactivated and used repeatedly. In this research, the heterogeneous catalyst from various source such as Lewatit macro porous resin, Amberlite gel resin and natural zeolite bayah was investigated their performance to produced biodiesel from used cooking oil. Initially, the preparation of the ion exchange process with variations in time, temperature, the concentration of HCl and NaOH solution was investigated. Then, the activity of heterogeneous catalyst to produced biodiesel under the variation of stirring rate, zeolite particle size, and comparison of different ion exchange catalysts were also investigated. Finally, the stability test and regeneration treatment were also investigated. The optimum operating conditions of biodiesel synthesis process is at the temperature of 60 °C for 2 h with a stirring speed of 700 rpm. Natural zeolite Bayah with 6 M of NaOH solution produced 16.19%, Amberlite gel with 6 M HCL produced 65.22% of biodiesel yield and material Lewatit macro porous with 6 M of NaOH solution produced 85.94% as the maximum result. As the best result, Material Lewatit macro porous selected as the material which was used in the variation of stirring speed, temperature, and reaction time, the concentration of base and stability test. According to the results of analysis, calculations yield methyl oleic HPLC produced by Lewatit macro porous with 6 M NaOH at 62.95%.

  19. Vitrification of cesium-contaminated organic ion exchange resin

    SciTech Connect

    Sargent, Jr., Thomas N.

    1994-08-01

    Vitrification has been declared by the Environmental Protection Agency (USEPA) as the Best Demonstrated Available Technology (BDAT) for the permanent disposal of high-level radioactive waste. Savannah River Site currently uses a sodium tetraphenylborate (NaTPB) precipitation process to remove Cs-137 from a wastewater solution created from the processing of nuclear fuel. This process has several disadvantages such as the formation of a benzene waste stream. It has been proposed to replace the precipitation process with an ion exchange process using a new resorcinol-formaldehyde resin developed by Savannah River Technical Center (SRTC). Preliminary tests, however, showed that problems such as crust formation and a reduced final glass wasteform exist when the resin is placed in the melter environment. The newly developed stirred melter could be capable of overcoming these problems. This research explored the operational feasibility of using the stirred tank melter to vitrify an organic ion exchange resin. Preliminary tests included crucible studies to determine the reducing potential of the resin and the extent of oxygen consuming reactions and oxygen transfer tests to approximate the extent of oxygen transfer into the molten glass using an impeller and a combination of the impeller and an external oxygen transfer system. These preliminary studies were used as a basis for the final test which was using the stirred tank melter to vitrify nonradioactive cesium loaded organic ion exchange resin. Results from this test included a cesium mass balance, a characterization of the semi-volatile organic compounds present in the off gas as products of incomplete combustion (PIC), a qualitative analysis of other volatile metals, and observations relating to the effect the resin had on the final redox state of the glass.

  20. Solid Phase Luminescence of Several Rare Earth Ions on Ion-Exchange Films

    NASA Technical Reports Server (NTRS)

    Tanner, Stephen P.; Street, Kenneth W., Jr.

    1999-01-01

    The development and characterization of a novel ion-exchange film for solid-phase fluorometry and phosphorimetry is reported. This new cation-exchange material is suitable for spectroscopic applications in the ultraviolet and visible regions. It is advantageous because it, as a single entity, is easily recovered from solution and mounted in the spectrofluorometers. After preconcentration on the film, the luminescence intensity of lanthanide ions is several orders of magnitude greater than that of the corresponding solution, depending on the volume of solution and the amount of film. This procedure allows emission spectral measurements and determination of lanthanide ions at solution concentrations of < 5 (micro)g/L. The film may be stored for subsequent reuse or as a permanent record of the analysis. The major drawback to the use of the film is slow uptake of analyte due to diffusion limitations.

  1. Molecular simulations of ion exchange in NaA zeolite membranes

    NASA Astrophysics Data System (ADS)

    Murad, S.; Jia, W.; Krishnamurthy, M.

    2003-02-01

    Molecular simulations using the method of molecular dynamics have been carried out to determine the possibility of studying ion exchanges between electrolyte solutions (here an aqueous LiCl solution) and an ion-exchange membrane (NaA zeolite) using direct simulations of upto a nanosecond. Our results show that with appropriate driving forces, such ion-exchange processes can be clearly witnessed and investigated using molecular simulations. We have also attempted to understand the phenomenon at the molecular level. Our results have shown that the ion-exchange process is energetically driven and entropic forces are not playing any significant role in the exchanges observed.

  2. Multistep ion exchange processes of gradient refractive index rod lens.

    PubMed

    Lv, Hao; Liu, Aimei; Tong, Jufang; Yi, Xunong; Li, Qianguang; Wang, Xinmin; Ding, Yaoming

    2011-01-01

    A mathematical model for research on the refractive index profile (RIP) of multistep ion exchange processes (IEPs) of gradient refractive index rod lenses (GRINs) is established by the different initial condition and boundary condition, based on the Fickian diffusion equation. GRIN rod lenses have been fabricated using the three-step IEPs. Research results indicate that the experimental deviations of refractive index (DRI) are in good agreement with the theoretical data. The DRI of three-step IEPs is superior to the one- and two-step IEPs and smaller than 10(-5).

  3. Extraction of hexavalent chromium from groundwater using ion exchange resins

    SciTech Connect

    Cottrell, D.; Ridley, M.

    1994-04-01

    A bench top experiment was performed to determine the hexavalent chromium (Cr{sup +6}) absorption capacity of three ion exchange resins. The resin types tested were Purolite A300, A500, and A600 which are commercially available. This experiment is part of an effort to better characterize resin efficiencies at removing Cr{sup +6} from ground water extracted from wells at the Lawrence Livermore National Laboratory. The information obtained from these laboratory scale tests will aid in the determination of the preferred resin for an onsite ground water treatment facility.

  4. Ion exchange of ammonium in natural and synthesized zeolites.

    PubMed

    Wang, Yifei; Lin, Feng; Pang, Wenqin

    2008-12-30

    In this study, zeolite Na-P and Na-Y was prepared by hydrothermal treatment of the Chinese natural clinoptilolite with NaOH. The ion exchange of NH4+ into the three zeolites in the temperature range of 288-333K was also investigated, and the thermodynamic parameters were calculated. The selectivity sequence for NH4+ entering the sodium form of the three materials was Na-clinoptilolite>Na-Y>Na-P, as indicated by values of DeltaG degrees . The results demonstrated that the Si/Al molar ratio of zeolites determined the selectivity for NH4+.

  5. Ion-exchange polymer artificial muscle and actuating system

    NASA Astrophysics Data System (ADS)

    Vial, Dominique; Tondu, Bertrand; Lopez, Pierre; Aurelle, Yves; Ricard, Alain

    1996-04-01

    Chemomechanical transformations are used to produce a mechanical force from a reversible chemical reaction in order to generate artificial muscular contraction, on the model of the biological muscle. The design and experimentation of an original artificial muscle using an ion-exchange polymer which reacts inside a soft envelope, derived from research on pneumatic artificial McKibben muscle, is presented. Then a chemomechanical actuator constituted of two artificial muscles has been conceived: first results are shown on position control in open-loop mode.

  6. Dual signal amplification for bioassays using ion release from nanolabels and ion-activated enzyme kinetics.

    PubMed

    Cowles, Chad L; Zhu, Xiaoshan

    2012-10-21

    A dual signal amplification technique was developed for bioassays. The technique consists of zinc-ion release from ZnS nanoparticle labels and enzyme kinetics activated by the released zinc ions as cofactors. In the ion release process, each ZnS nanoparticle label liberates a high number of zinc ions by acidic dissolution. After the ion release, at appropriate pH levels, the released zinc ions are used as cofactors to trigger the enzymatic activity of carbonic anhydrase. The fluorescence produced from the activated enzyme kinetics is measured for bioassay signal quantification. A model bioassay on mouse IgG adopting this technique presents a detection limit around 0.5 pM and a detection range over at least two orders of magnitude. This technique was also successfully applied to the detection of human cardiac troponin I (cTnI) in human serum samples to demonstrate a clinical diagnosis application. The developed immunoassay is capable of distinguishing clinically critical levels of cTnI. This technique possesses a high detection resolution and offers the advantage of straightforward operation (simple preparation of ZnS nanoparticles and no enzyme immobilization).

  7. ION EXCHANGE SUBSTANCES BY SAPONIFICATION OF ALLYL PHOSPHATE POLYMERS

    DOEpatents

    Kennedy, J.

    1959-04-14

    An ion exchange resin having a relatively high adsorption capacity tor uranyl ion as compared with many common cations is reported. The resin comprises an alphyl-allyl hydrogen phosphate polymer, the alphyl group being either allyl or a lower alkyl group having up to 5 carbon atoins. The resin is prepared by polymerizing compounds such as alkyl-diallyl phosphate and triallyl phosphate in the presence of a free radical generating substance and then partially hydrolyzing the resulting polymer to cause partial replacement of organic radicals by cations. A preferred free radical gencrating agent is dibenzoyl peroxide. The partial hydrolysis is brought about by refluxing the polymer with concentrated aqueous NaOH for three or four hours.

  8. FDM study of ion exchange diffusion equation in glass

    NASA Astrophysics Data System (ADS)

    Zhou, Zigang; Yang, Yongjia; Wang, Qiang; Sun, Guangchun

    2009-05-01

    Ion-exchange technique in glass was developed to fabricate gradient refractive index optical devices. In this paper, the Finite Difference Method(FDM), which is used for the solution of ion-diffusion equation, is reported. This method transforms continual diffusion equation to separate difference equation. It unitizes the matrix of MATLAB program to solve the iteration process. The collation results under square boundary condition show that it gets a more accurate numerical solution. Compared to experiment data, the relative error is less than 0.2%. Furthermore, it has simply operation and kinds of output solutions. This method can provide better results for border-proliferation of the hexagonal and the channel devices too.

  9. Extraction and ion-exchange behavior of mendelevium (II)

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.; Buklanov, G.V.; Pkhar, Z.Z.; Lebedev, I.A.; Katargin, N.V.; Myasoedov, B.F.

    1988-09-01

    Medelevium-256 was obtained via multinucleon transfer reactions upon irradiation of /sup 249/Bk by /sup 22/Ne ions from the extracted beam of a U-300 cyclotron. In order to extract mendelevium and separate it from the products of nuclear reactions, an express ion-exchange method using one column with cationite and zinc amalgam in a solution of 1 mole/liter HCl as the eluent was developed. It was shown that under these conditions mendelevium is reduced and washes out as an alkaline earth element. On the basis of the location of the peaks of the elution curves of Sr/sup 2+/, Eu/sup 2+/, and Md/sup 2+/, the value of the ionic radium of Md/sup 2+/ is estimated and is used to estimate the heat of hydration.

  10. New Charge Exchange Calculations for Lowly-Charged Ions

    NASA Astrophysics Data System (ADS)

    Stancil, P. C.

    2005-05-01

    The process of charge exchange, which occurs during the collision of an ion with a neutral species, is important in a variety of astrophysical and atmospheric environments. It can have an influence on the ionization and thermal balances of the plasma and may also contribute to the emission spectrum. The charge exchange of multiply-charged ions (q>2) usually proceeds at a fast rate with rate coefficients typically of 10-10 to 10-9 cm3s-1. Therefore, highly-charged ions, which are created in UV or x-ray ionized gas, quickly recombine to smaller charges. However, the rate coefficients for singly- and doubly-charged ions can vary over five orders of magnitude depending on the ion species, the neutral target, and the temperature. In particular, the rate coefficients depend sensitively on the dominant mechanism which may be due to radial, rotational, radiative, or spin-orbit coupling and the corresponding quasi-molecular curves can be very complicated. Measurements of such processes are complicated by metastable contamination and uncertainties in target purity and estimates of empirical values inferred from astrophysical modeling are typically suspect. Therefore, the state of knowledge of lowly-charged electron transfer processes is generally poor, but these reactions can be critical in determining the state of the plasma. If, for example, the rate coefficient for a q=2 ion is very small, the process would result in a bottle-neck in the recombination cascade from higer charges. In an effort to address these problems, quantum-mechanical calculations have been carried out for a number of singly- and doubly-charged ions and benchmarked to measurements when available. I will present a summary of these results which reveal significant differences from values adopted in rate coefficient compilations used by various modeling packages. This work was performed in collaboration with L. B. Zhao, C. Y. Lin, J. P. Gu, H. P. Liebermann, R. J. Buenker, and M. Kimura. Support from NASA

  11. Partitioning of mobile ions between ion exchange polymers and aqueous salt solutions: importance of counter-ion condensation.

    PubMed

    Kamcev, Jovan; Galizia, Michele; Benedetti, Francesco M; Jang, Eui-Soung; Paul, Donald R; Freeman, Benny D; Manning, Gerald S

    2016-02-17

    Equilibrium partitioning of ions between a membrane and a contiguous external solution strongly influences transport properties of polymeric membranes used for water purification and energy generation applications. This study presents a theoretical framework to quantitatively predict ion sorption from aqueous electrolytes (e.g., NaCl, MgCl2) into charged (i.e., ion exchange) polymers. The model was compared with experimental NaCl, MgCl2, and CaCl2 sorption data in commercial cation and anion exchange membranes. Ion sorption in charged polymers was modeled using a thermodynamic approach based on Donnan theory coupled with Manning's counter-ion condensation theory to describe non-ideal behavior of ions in the membrane. Ion activity coefficients in solution were calculated using the Pitzer model. The resulting model, with no adjustable parameters, provides remarkably good agreement with experimental values of membrane mobile salt concentration. The generality of the model was further demonstrated using literature data for ion sorption of various electrolytes in charged polymers, including HCl sorption in Nafion.

  12. Nonparametric analysis of nonexponential and multidimensional kinetics. I. Quantifying rate dispersion, rate heterogeneity, and exchange dynamics.

    PubMed

    Berg, Mark A; Kaur, Harveen

    2017-02-07

    The quantification of nonexponential (dispersed) kinetics has relied on empirical functions, which yield parameters that are neither unique nor easily related to the underlying mechanism. Multidimensional kinetics provide more information on dispersed processes, but a good approach to their analysis is even less clear than for standard, one-dimensional kinetics. This paper is the first in a series that analyzes kinetic data in one or many dimensions with a scheme that is nonparametric: it quantifies nonexponential decays without relying on a specific functional form. The quantities obtained are directly related to properties of the mechanism causing the rate dispersion. Log-moments of decays, which parallel the standard moments of distributions (mean, standard deviation, etc.), are introduced for both one- and multi-dimensional decays. Kinetic spectra are defined to visualize the data. The utility of this approach is demonstrated on a simple, but general, model of dispersed kinetics-a nonexponential homogeneous decay combined with slowly exchanging rate heterogeneity. The first log-moments give a geometric-mean relaxation time. Second log-moments quantify the magnitude of rate dispersion, the fraction of the dispersion due to heterogeneity, and the dynamics of exchange between different rate subensembles. A suitable combination of these moments isolates exchange dynamics from three-dimensional kinetics without contamination by the rate-filtering effects that were identified in a recent paper [M. A. Berg and J. R. Darvin, J. Chem. Phys. 145, 054119 (2016)].

  13. Kinetic Studies with Ion Selective Electrodes: Determination of Creatinine in Urine with a Picrate Ion Selective Electrode: A Laboratory Experiment.

    ERIC Educational Resources Information Center

    Diamandis, E. P.; And Others

    1983-01-01

    The kinetic of the Jaffe reaction with picrate ion selective electrode (ISE) and a kinetic method for determining creatinine in urine is presented. The experiment could be used to familarize students with the application of ISE in kinetic studies and chemical analysis. (Author/JN)

  14. Kinetic ion-acoustic solitary waves in collisional plasmas

    NASA Astrophysics Data System (ADS)

    Pezzi, Oreste; Valentini, Francesco; Veltri, Pierluigi

    2014-05-01

    The excitation and the propagation of solitary waves of ion-acoustic nature are analyzed by means of kinetic Eulerian simulations, in both collision-free and collisional plasmas, composed of kinetic warm protons and linear Boltzmannian electrons. The process of soliton formation is discussed in detail through the description of the time evolution of the electrostatic potential and of the associated phase space portraits of the proton distribution function. We study the effects of collisions on the propagation of solitary waves, by modeling proton-proton interactions through the one-dimensional nonlinear Dougherty operator, which is a collisional operator of the Fokker-Planck type. We show how, in a case of non-negligible collisionality, short spatial scales in the electrostatic potential are dissipated in time and the phase space structures, observed in the distribution function in absence of collisions, are significantly smoothed out. Finally, by exploiting the analogy between ion-acoustic waves in neutral infinite plasma and Trivelpiece-Gould waves in nonneutral plasmas columns, a recipe to observe solitary structures in nonneutral plasma devices is proposed.

  15. Emergence of ion channel modal gating from independent subunit kinetics.

    PubMed

    Bicknell, Brendan A; Goodhill, Geoffrey J

    2016-09-06

    Many ion channels exhibit a slow stochastic switching between distinct modes of gating activity. This feature of channel behavior has pronounced implications for the dynamics of ionic currents and the signaling pathways that they regulate. A canonical example is the inositol 1,4,5-trisphosphate receptor (IP3R) channel, whose regulation of intracellular Ca(2+) concentration is essential for numerous cellular processes. However, the underlying biophysical mechanisms that give rise to modal gating in this and most other channels remain unknown. Although ion channels are composed of protein subunits, previous mathematical models of modal gating are coarse grained at the level of whole-channel states, limiting further dialogue between theory and experiment. Here we propose an origin for modal gating, by modeling the kinetics of ligand binding and conformational change in the IP3R at the subunit level. We find good agreement with experimental data over a wide range of ligand concentrations, accounting for equilibrium channel properties, transient responses to changing ligand conditions, and modal gating statistics. We show how this can be understood within a simple analytical framework and confirm our results with stochastic simulations. The model assumes that channel subunits are independent, demonstrating that cooperative binding or concerted conformational changes are not required for modal gating. Moreover, the model embodies a generally applicable principle: If a timescale separation exists in the kinetics of individual subunits, then modal gating can arise as an emergent property of channel behavior.

  16. Emergence of ion channel modal gating from independent subunit kinetics

    PubMed Central

    Bicknell, Brendan A.

    2016-01-01

    Many ion channels exhibit a slow stochastic switching between distinct modes of gating activity. This feature of channel behavior has pronounced implications for the dynamics of ionic currents and the signaling pathways that they regulate. A canonical example is the inositol 1,4,5-trisphosphate receptor (IP3R) channel, whose regulation of intracellular Ca2+ concentration is essential for numerous cellular processes. However, the underlying biophysical mechanisms that give rise to modal gating in this and most other channels remain unknown. Although ion channels are composed of protein subunits, previous mathematical models of modal gating are coarse grained at the level of whole-channel states, limiting further dialogue between theory and experiment. Here we propose an origin for modal gating, by modeling the kinetics of ligand binding and conformational change in the IP3R at the subunit level. We find good agreement with experimental data over a wide range of ligand concentrations, accounting for equilibrium channel properties, transient responses to changing ligand conditions, and modal gating statistics. We show how this can be understood within a simple analytical framework and confirm our results with stochastic simulations. The model assumes that channel subunits are independent, demonstrating that cooperative binding or concerted conformational changes are not required for modal gating. Moreover, the model embodies a generally applicable principle: If a timescale separation exists in the kinetics of individual subunits, then modal gating can arise as an emergent property of channel behavior. PMID:27551100

  17. Oxygen exchange reaction kinetics for cerium(IV) oxide at 1000 °C

    SciTech Connect

    Whiting, Christofer E. Douglas, John M.; Cremeans, Bethany M.; Barklay, Chadwick D.; Kramer, Daniel P.

    2014-10-15

    Bulk oxygen exchange rate kinetics on CeO{sub 2} at 1000 °C were observed to have a first order dependence on the fraction of reaction remaining and to be independent of oxygen partial pressure, total pressure, particle size, and specific surface area. This suggests that the exchange reaction is dominated by an internal chemical reaction that is occurring throughout the bulk of the material, and not at the material surface. Oxygen exchange rates were limited by this internal chemical reaction for all CeO{sub 2} powders studied (15 nm to −325 mesh), and had a rate constant of 1.19×10{sup −2} s{sup −1} with a time to completion of 617 s. These results are similar to the exchange rates observed previously on PuO{sub 2}, suggesting that oxygen exchange on PuO{sub 2} may also be dominated by an internal chemical reaction under similar conditions. This work will help guide future experiments on {sup 238}PuO{sub 2} oxygen exchange reactions. - Graphical abstract: Oxygen exchange kinetics on CeO{sub 2} at 1000 °C are independent of a wide range of experimental conditions and exhibit first-order chemical reaction kinetics. - Highlights: • Stable oxygen exchange rates obtained on a variety of CeO{sub 2} powders at 1000 °C. • Exchange rates are independent of atmospheric composition and specific surface area. • Exchange rates are limited by an internal chemical reaction, not a surface reaction. • CeO{sub 2} exchange rates appear similar to the rates observed on PuO{sub 2} at 1000 °C.

  18. Ion-release kinetics and ecotoxicity effects of silver nanoparticles.

    PubMed

    Lee, Yong-Ju; Kim, Jiwon; Oh, Jeehyun; Bae, Sujin; Lee, Sungkyu; Hong, In Seok; Kim, Sang-Ho

    2012-01-01

    The environmental toxicity associated with silver nanoparticles (AgNPs) has been a major focus in nanotoxicology. The Ag(+) released from AgNPs may affect ecotoxicity, although whether the major toxic effect is governed by Ag(+) ions or by AgNPs themselves is unclear. In the present study, we have examined the ecotoxicity of AgNPs in aquatic organisms, silver ion-release kinetics of AgNPs, and their relationship. The 48-h median effective concentration (EC50) values for Daphnia magna of powder-type AgNP suspensions were 0.75 µg/L (95% confidence interval [CI] = 0.71-0.78) total Ag and 0.37 µg/L (95% CI = 0.36-0.38) dissolved Ag. For sol-type AgNP suspension, the 48-h EC50 values for D. magna were 7.98 µg/L (95% CI = 7.04-9.03) total Ag and 0.88 µg/L (95% CI = 0.80-0.97) dissolved Ag. The EC50 values for the dissolved Ag of powder-type and sol-type AgNPs for D. magna showed similar results (0.37 µg/L and 0.88 µg/L) despite their differences of EC50 values in total Ag. We observed that the first-order rate constant (k) of Ag(+) ions released from AgNPs was 0.0734/h at 0.05 mg/L total Ag at 22°C within 6 h. The kinetic experiments and the toxicity test showed that 36% and 11% of sol-type AgNPs were converted to the Ag(+) ion form under oxidation conditions, respectively. Powder-type AgNPs showed 49% conversion rate of Ag(+) ion from AgNPs. We also confirmed that Ag(+) ion concentration in AgNP suspension reaches an equilibrium concentration after 48 h, which is an exposure time of the acute aquatic toxicity test.

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  20. Evaluation of Ion Exchange Materials in K Basin Floor Sludge and Potential Solvents for PCB Extraction from Ion Exchange Materials

    SciTech Connect

    Schmidt, A.J.; Klinger, G.S.; Bredt, P.R.

    1999-04-10

    Approximately 73 m{sup 3} of heterogeneous solid material, ''sludge,'' (upper bound estimate, Packer 1997) have accumulated at the bottom of the K Basins in the 100 K Area of the Hanford Site. This sludge is a mixture of spent fuel element corrosion products, ion exchange materials (organic and inorganic), graphite-based gasket materials, iron and aluminum metal corrosion products, sand, and debris (Makenas et al. 1996, 1997). In addition, small amounts of polychlorinated biphenyls (PCBs) have been found. These small amounts are significant from a regulatory standpoint. Ultimately, it is planned to transfer the K Basins sludge to the Hanford double shell tanks (DSTs). Chemical pretreatment is required to address criticality issues and the destruction or removal of PCBs before the K Basin sludge can be transferred to the DSTs. Eleven technologies have been evaluated (Papp 1997) as potential pretreatment methods. Based on the evaluations and engineering studies and limited testing, Fluor Daniel Hanford recommended solvent washing of the K Basin sludge, followed by nitric acid dissolution and, potentially, peroxide addition (FDH 1997). The solvent washing (extraction) and peroxide addition would be used to facilitate PCB removal and destruction. Following solvent extraction, the PCBs could be distilled and concentrated for disposal as a low-level waste. The purpose of the work reported here was to continue investigating solvent extraction, first by better identifying the ion exchange materials in the actual sludge samples and then evaluating various solvents for removing the PCBs or possibly dissolving the resins. This report documents some of the process knowledge on ion exchange materials used and spilled in the K Basins and describes the materials identified from wet sieving KE Basin floor and canister sludge and the results of other analyses. Several photographs are included to compare materials and illustrate material behavior. A summary of previous tests on

  1. Roles of Bulk and Surface Chemistry in the Oxygen Exchange Kinetics and Related Properties of Mixed Conducting Perovskite Oxide Electrodes

    PubMed Central

    Perry, Nicola H.; Ishihara, Tatsumi

    2016-01-01

    Mixed conducting perovskite oxides and related structures serving as electrodes for electrochemical oxygen incorporation and evolution in solid oxide fuel and electrolysis cells, respectively, play a significant role in determining the cell efficiency and lifetime. Desired improvements in catalytic activity for rapid surface oxygen exchange, fast bulk transport (electronic and ionic), and thermo-chemo-mechanical stability of oxygen electrodes will require increased understanding of the impact of both bulk and surface chemistry on these properties. This review highlights selected work at the International Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, set in the context of work in the broader community, aiming to characterize and understand relationships between bulk and surface composition and oxygen electrode performance. Insights into aspects of bulk point defect chemistry, electronic structure, crystal structure, and cation choice that impact carrier concentrations and mobilities, surface exchange kinetics, and chemical expansion coefficients are emerging. At the same time, an understanding of the relationship between bulk and surface chemistry is being developed that may assist design of electrodes with more robust surface chemistries, e.g., impurity tolerance or limited surface segregation. Ion scattering techniques (e.g., secondary ion mass spectrometry, SIMS, or low energy ion scattering spectroscopy, LEIS) with high surface sensitivity and increasing lateral resolution are proving useful for measuring surface exchange kinetics, diffusivity, and corresponding outer monolayer chemistry of electrodes exposed to typical operating conditions. Beyond consideration of chemical composition, the use of strain and/or a high density of active interfaces also show promise for enhancing performance. PMID:28773978

  2. Ion exchangers in radioactive waste management: natural Iranian zeolites.

    PubMed

    Nilchi, A; Maalek, B; Khanchi, A; Ghanadi Maragheh, M; Bagheri, A; Savoji, K

    2006-01-01

    Five samples of natural zeolites from different parts of Iran were chosen for this study. In order to characterize and determine their structures, X-ray diffraction and infrared spectrometry were carried out for each sample. The selective absorption properties of each zeolite were found by calculating the distribution coefficient (K(d)) of various simulated wastes which were prepared by spiking the radionuclides with (131)I, (99)Mo, (153)Sm, (140)La and (147)Nd. All the zeolite samples used in this study had extremely high absorption value towards (140)La; clinoptolite from Mianeh and analsite from Ghalehkhargoshi showed good absorption for (147)Nd; clinoptolite from Semnan and clinoptolite from Firozkoh showed high absorption for (153)Sm; mesolite from Arababad Tabas showed good absorption for (99)Mo; and finally mesolite from Arababad Tabas, clinoptolite from Semnan and clinoptolite from Firozkoh could be used to selectively absorb (131)I from the stimulated waste which was prepared. The natural zeolites chosen for these studies show a similar pattern to those synthetic ion exchangers in the literature and in some cases an extremely high selectivity towards certain radioactive elements. Hence the binary separation of radioactive elements could easily be carried out. Furthermore, these zeolites, which are naturally occurring ion exchangers, are viable economically and extremely useful alternatives in this industry.

  3. Ion exchange at TNX using the SKID unit

    SciTech Connect

    Meyer, M.L.; Bibler, J.P.

    1993-10-21

    An ion exchange unit has been manufactured for WSRC by British Nuclear Fuels, Ltd. This unit consists of three columns, ancillary valving, pumps, lines, and computer controls. It has been delivered to TNX for use in testing a cesium-specific ion exchange resin, developed at WSRC as a potential second generation process for the decontamination of Defense Waste Processing Facility (DWPF) supernate. This resin also has Department of Energy applications at both Oak Ridge and Hanford. Oak Ridge is interested in decontaminating the Melton Valley storage tank supernate, while Hanford is interested in decontaminating the 101-AW and 101-SY supernate streams. Another potential developmental interest is the Savannah River Site (SRS) DWPF recycle stream. The three primary waste streams of interest are the Oak Ridge, Hanford, and SRS, SWPF supernate streams. For these three waste streams, the cesium decontamination factor (DF) will be measured for a non-radioactive, simulated, high-level waste solution. The test objectives, process outlines, and broad characterization of the waste streams are described.

  4. Synthesis of layered sodium lanthanum selenide through ion exchange reactions

    SciTech Connect

    Butts, Laura J.; Strickland, Nicholas; Martin, Benjamin R.

    2009-04-02

    Layered hexagonal KLaSe2 ({alpha}-NaFeO{sub 2}-type) was synthesized using the reactive flux method and analyzed by powder XRD to determine its lattice constants (space group R-3m, a = 4.40508(5) A, c = 22.7838(5) A). NaLaSe{sub 2}, which normally crystallizes as a disordered rock salt structure with mixed Na+/La + 3 sites, was synthesized through a solid state ion exchange reaction at 585 deg. C from a 1:3 molar ratio mixture of KLaSe{sub 2}:NaI. The product of this reaction was hexagonally layered NaLaSe{sub 2} (space group R-3m, a = 4.3497(3) A, c = 20.808(2) A) isostructural to KLaSe{sub 2}. This product was analyzed by comparison with members of the set of solid solutions Na{sub (1-x)}K{sub (x)}LaSe{sub 2} to confirm that the extent ion exchange in this reaction was complete. Cubic (disordered) NaLaSe{sub 2} was also reacted with KI to yield the poorly crystalline hexagonally layered product with the approximate formula Na{sub 0.79}K{sub 0.21}LaSe{sub 2}.

  5. Radiation stability of sodium titanate ion exchange materials

    SciTech Connect

    Kenna, B.T.

    1980-02-01

    Sodium titanate and sodium titanate loaded macroreticular resin are being considered as ion exchangers to remove /sup 90/Sr and actinides from the large volume of defense waste stored at Hanford Site in Washington. Preliminary studies to determine the radiation effect on Sr/sup +2/ and I/sup -/ capacity of these ion-exchange materials were conducted. Samples of sodium titanate powder, sodium titanate loaded macroreticular resin, as well as the nitrate form of macroreticular anion resin were irradiated with up to 2 x 10/sup 9/ Rads of /sup 60/Co gamma rays. Sodium titanate cation capacity decreased about 50% while the sodium titanate loaded macroeticular resin displayed a dramatic decrease in cation capacity when irradiated with 10/sup 8/-10/sup 9/ Rad. The latter decrease is tentatively ascribed to radiation damage to the organic portion which subsequently inhibits interaction with the contained sodium titanate. The anion capacity of both macroreticular resin and sodium titanate loaded macroreticular resin exhibited significant decreases with increasing radiation exposure. These results suggest that consideration should be given to the potential effects of radiation degradation if column regeneration is to be used. 5 figures, 2 tables.

  6. Small Column Ion Exchange Monitor System Final Report

    SciTech Connect

    CASELLA, VITO

    2004-09-30

    A Small Column Ion Exchange (SCIX) system has been designed by the Oak Ridge and Savannah River National Laboratories (ORNL and SRNL) as a potential way to reduce Cs-137 concentrations in high-level radioactive waste at the Savannah River Site. SRNL was asked to develop gamma-ray monitors at six locations within the SCIX system. Gamma-ray monitors are required to verify the proper operation of the ion exchange system, detect cesium breakthrough, and confirm presence of cesium before and after used resin is transferred to a grinder module. The only observable gamma ray in the decay of Cs-137 is from its short-lived Ba-137m daughter. Chemical processes, such as the SCIX, may disrupt the secular equilibrium between this parent-daughter pair; meaning that measurement of Ba-137m will not necessarily yield information about Cs-137 content. While this is a complicating factor that can not be ignored, it is controllable by either: allowing sufficient time for equilibrium to be reestablished (about 20 minutes), or by making multiple measurements with sufficient statistical precision to determine the extent of disequilibrium. The present work provides a means of measuring the Cs-137 and Ba-137m by taking multiple measurements in a process isolation loop that contains the process solution of interest.

  7. A Simulation Model for the Toroidal Ion Temperature Gradient Instability with Fully Kinetic Ions

    NASA Astrophysics Data System (ADS)

    Sturdevant, Benjamin; Parker, Scott; Chen, Yang

    2016-10-01

    A simulation model for the toroidal ITG mode in which the ions follow the primitive Lorentz force equations of motion is presented. Such a model can provide an important validation tool or replacement for gyrokinetic ion models in applications where higher order terms may be important. A number of multiple-scale simulation techniques are employed in this work, based on the previous success in slab geometry with an implicit orbit averaged and sub-cycled δf model. For the toroidal geometry model, we have derived a particle integration scheme based on variational principles, which is demonstrated to produce stable and accurate ion trajectories on long time scales. Orbit averaging and sub-cycling will be implemented with the variational integration scheme. The inclusion of equilibrium gradients in the fully kinetic δf formulation is achieved through the use of a guiding center coordinate transformation of the weight equation. Simulation results for the fully kinetic ion model will be presented for the cyclone base case and comparisons will be made with gyrokinetic ion models.

  8. Enhanced DOC removal using anion and cation ion exchange resins.

    PubMed

    Arias-Paic, Miguel; Cawley, Kaelin M; Byg, Steve; Rosario-Ortiz, Fernando L

    2016-01-01

    Hardness and DOC removal in a single ion exchange unit operation allows for less infrastructure, is advantageous for process operation and depending on the water source, could enhance anion exchange resin removal of dissolved organic carbon (DOC). Simultaneous application of cationic (Plus) and anionic (MIEX) ion exchange resin in a single contact vessel was tested at pilot and bench scales, under multiple regeneration cycles. Hardness removal correlated with theoretical predictions; where measured hardness was between 88 and 98% of the predicted value. Comparing bench scale DOC removal of solely treating water with MIEX compared to Plus and MIEX treated water showed an enhanced DOC removal, where removal was increased from 0.5 to 1.25 mg/L for the simultaneous resin application compared to solely applying MIEX resin. A full scale MIEX treatment plant (14.5 MGD) reduced raw water DOC from 13.7 mg/L to 4.90 mg/L in the treated effluent at a bed volume (BV) treatment rate of 800, where a parallel operation of a simultaneous MIEX and Plus resin pilot (10 gpm) measured effluent DOC concentrations of no greater than 3.4 mg/L, even at bed volumes of treatment 37.5% greater than the full scale plant. MIEX effluent compared to simultaneous Plus and MIEX effluent resulted in differences in fluorescence intensity that correlated to decreases in DOC concentration. The simultaneous treatment of Plus and MIEX resin produced water with predominantly microbial character, indicating the enhanced DOC removal was principally due to increased removal of terrestrially derived organic matter. The addition of Plus resin to a process train with MIEX resin allows for one treatment process to remove both DOC and hardness, where a single brine waste stream can be sent to sewer at a full-scale plant, completely removing lime chemical addition and sludge waste disposal for precipitative softening processes.

  9. Stochastic effects in a discretized kinetic model of economic exchange

    NASA Astrophysics Data System (ADS)

    Bertotti, M. L.; Chattopadhyay, A. K.; Modanese, G.

    2017-04-01

    Linear stochastic models and discretized kinetic theory are two complementary analytical techniques used for the investigation of complex systems of economic interactions. The former employ Langevin equations, with an emphasis on stock trade; the latter is based on systems of ordinary differential equations and is better suited for the description of binary interactions, taxation and welfare redistribution. We propose a new framework which establishes a connection between the two approaches by introducing random fluctuations into the kinetic model based on Langevin and Fokker-Planck formalisms. Numerical simulations of the resulting model indicate positive correlations between the Gini index and the total wealth, that suggest a growing inequality with increasing income. Further analysis shows, in the presence of a conserved total wealth, a simultaneous decrease in inequality as social mobility increases, in conformity with economic data.

  10. Ammonia removal from wastewater by ion exchange in the presence of organic contaminants.

    PubMed

    Jorgensen, T C; Weatherley, L R

    2003-04-01

    The scope of this study was the removal of ammonium by ion exchange from simulated wastewater. The study looks at the effect of organics upon ammonium ion exchange equilibrium uptake. The ion exchangers included a natural zeolite clinoptilolite, and two polymeric exchangers, Dowex 50w-x8, and Purolite MN500. The organic compounds studied included citric acid and a number of proteins. The traditional method for removal of ammonium and organic pollutants from wastewater is biological treatment, but ion exchange offers a number of advantages including the ability to handle shock loadings and the ability to operate over a wider range of temperatures. The results show that in most of the cases studied, the presence of organic compounds enhances the uptake of ammonium ion onto the ion exchangers.

  11. On the influence of ion exchange on the local structure of the titanosilicate ETS-10.

    PubMed

    Pavel, Claudiu C; Zibrowius, Bodo; Löffler, Elke; Schmidt, Wolfgang

    2007-07-14

    The effect of ion exchange with different monovalent cations (NH(4)(+), K(+), Na(+) and Cs(+)) on the local structure of the titanosilicate ETS-10 has been studied by (29)Si MAS NMR and Raman spectroscopy. Although X-ray diffraction shows no significant influence of ion exchange on the long range order, ammonium exchange is found to result in substantial damage to the local structure. Ion exchange experiments with alkali cations under significantly more acidic conditions clearly show that the structural damage brought about by ammonium exchange is not caused by the low pH of the exchange solution. The exchange with potassium and caesium ions also leads to significant changes in the (29)Si NMR and Raman spectra. However, these changes can largely be reversed by sodium back-exchange.

  12. Inequality measures in kinetic exchange models of wealth distributions

    NASA Astrophysics Data System (ADS)

    Ghosh, Asim; Chatterjee, Arnab; Inoue, Jun-ichi; Chakrabarti, Bikas K.

    2016-06-01

    In this paper, we study the inequality indices for some models of wealth exchange. We calculated Gini index and newly introduced k-index and compare the results with reported empirical data available for different countries. We have found lower and upper bounds for the indices and discuss the efficiencies of the models. Some exact analytical calculations are given for a few cases. We also exactly compute the quantities for Gamma and double Gamma distributions.

  13. Nonparametric analysis of nonexponential and multidimensional kinetics. I. Quantifying rate dispersion, rate heterogeneity, and exchange dynamics

    NASA Astrophysics Data System (ADS)

    Berg, Mark A.; Kaur, Harveen

    2017-02-01

    The quantification of nonexponential (dispersed) kinetics has relied on empirical functions, which yield parameters that are neither unique nor easily related to the underlying mechanism. Multidimensional kinetics provide more information on dispersed processes, but a good approach to their analysis is even less clear than for standard, one-dimensional kinetics. This paper is the first in a series that analyzes kinetic data in one or many dimensions with a scheme that is nonparametric: it quantifies nonexponential decays without relying on a specific functional form. The quantities obtained are directly related to properties of the mechanism causing the rate dispersion. Log-moments of decays, which parallel the standard moments of distributions (mean, standard deviation, etc.), are introduced for both one- and multi-dimensional decays. Kinetic spectra are defined to visualize the data. The utility of this approach is demonstrated on a simple, but general, model of dispersed kinetics—a nonexponential homogeneous decay combined with slowly exchanging rate heterogeneity. The first log-moments give a geometric-mean relaxation time. Second log-moments quantify the magnitude of rate dispersion, the fraction of the dispersion due to heterogeneity, and the dynamics of exchange between different rate subensembles. A suitable combination of these moments isolates exchange dynamics from three-dimensional kinetics without contamination by the rate-filtering effects that were identified in a recent paper [M. A. Berg and J. R. Darvin, J. Chem. Phys. 145, 054119 (2016)].

  14. A time-resolved study on the interaction of oppositely charged bicelles--implications on the charged lipid exchange kinetics.

    PubMed

    Yang, Po-Wei; Lin, Tsang-Lang; Hu, Yuan; Jeng, U-Ser

    2015-03-21

    Time-resolved small-angle X-ray scattering was applied to study charged lipid exchange between oppositely charged disc-shaped bicelles. The exchange of charged lipids gradually reduces the surface charge density and weakens the electrostatic attraction between the oppositely charged bicelles which form alternately stacked aggregates upon mixing. Initially, at a high surface charge density with almost no free water layer between the stacked bicelles, fast exchange kinetics dominate the exchange process. At a later stage with a lower surface charge density and a larger water gap between the stacked bicelles, slow exchange kinetics take over. The fast exchange kinetics are correlated with the close contact of the bicelles when there is almost no free water layer between the tightly bound bicelles with a charged lipid exchange time constant as short as 20-40 min. When the water gap becomes large enough to have a free water layer between the stacked bicelles, the fast lipid exchange kinetics are taken over by slow lipid exchange kinetics with time constants around 200-300 min, which are comparable to the typical time constant of lipid exchange between vesicles in aqueous solution. These two kinds of exchange mode fit well with the lipid exchange models of transient hemifusion for the fast mode and monomer exchange for the slow mode.

  15. Fabrication and characterization planar waveguides of Na+-Ag+/K+ by ion exchange and prism coupler

    NASA Astrophysics Data System (ADS)

    Yulianto, Muchlas; Marzuki, Ahmad; Suryanti, Venty

    2017-08-01

    This paper reports about the fabrication of planar waveguides made of the ion-exchanged technique on a soda-lime glass. The process of the ion-exchanged occurs between Na+ ions from the soda-lime glass and Ag+/K+ ions from molten salt AgNO3+KNO3. Fabrication is conducted at 70 mol% of KNO3 and 30 mol% of an AgNO3 melt takes place for the realization of planar waveguides. The duration of ion-exchanged has been varied in the range of 25-900 minutes at the temperature of 350°C to diffusion processes. The purpose of our experiments is especially to study the effect of duration of the ion-exchange process to the main parameters used to characterized optical waveguides. The optical transmission spectra of the ion exchanged glasses were measured with a single beam UV/Visible Ocean Optics USB4000 Spectrometer. The refractive index change, the number of modes waveguides, and diffusion depth had been investigated. The m-lines spectroscopy with standard prism-coupling technique at 632,8 nm was used to measure the number of modes and depth of waveguides. Refractive index was measured with ABBE refractometer. The result shows that the glass refractive index change values of the ion-exchanged glasses are independent of both the ion exchange duration. The number of modes and the diffusion depth, however increase with increasing the duration of ion-exchange processes.

  16. Li+ solvation and kinetics of Li+-BF4-/PF6- ion pairs in ethylene carbonate. A molecular dynamics study with classical rate theories

    NASA Astrophysics Data System (ADS)

    Chang, Tsun-Mei; Dang, Liem X.

    2017-10-01

    Using our polarizable force-field models and employing classical rate theories of chemical reactions, we examine the ethylene carbonate (EC) exchange process between the first and second solvation shells around Li+ and the dissociation kinetics of ion pairs Li+-[BF4] and Li+-[PF6] in this solvent. We calculate the exchange rates using transition state theory and correct them with transmission coefficients computed by the reactive flux, Impey, Madden, and McDonald approaches, and Grote-Hynes theory. We found that the residence times of EC around Li+ ions varied from 60 to 450 ps, depending on the correction method used. We found that the relaxation times changed significantly from Li+-[BF4] to Li+-[PF6] ion pairs in EC. Our results also show that, in addition to affecting the free energy of dissociation in EC, the anion type also significantly influences the dissociation kinetics of ion pairing.

  17. Small Column Ion Exchange Design and Safety Strategy

    SciTech Connect

    Huff, T.; Rios-Armstrong, M.; Edwards, R.; Herman, D.

    2011-02-07

    Small Column Ion Exchange (SCIX) is a transformational technology originally developed by the Department of Energy (DOE) Environmental Management (EM-30) office and is now being deployed at the Savannah River Site (SRS) to significantly increase overall salt processing capacity and accelerate the Liquid Waste System life-cycle. The process combines strontium and actinide removal using Monosodium Titanate (MST), Rotary Microfiltration, and cesium removal using Crystalline Silicotitanate (CST, specifically UOP IONSIV{reg_sign}IE-911 ion exchanger) to create a low level waste stream to be disposed in grout and a high level waste stream to be vitrified. The process also includes preparation of the streams for disposal, e.g., grinding of the loaded CST material. These waste processing components are technically mature and flowsheet integration studies are being performed including glass formulations studies, application specific thermal modeling, and mixing studies. The deployment program includes design and fabrication of the Rotary Microfilter (RMF) assembly, ion-exchange columns (IXCs), and grinder module, utilizing an integrated system safety design approach. The design concept is to install the process inside an existing waste tank, Tank 41H. The process consists of a feed pump with a set of four RMFs, two IXCs, a media grinder, three Submersible Mixer Pumps (SMPs), and all supporting infrastructure including media receipt and preparation facilities. The design addresses MST mixing to achieve the required strontium and actinide removal and to prevent future retrieval problems. CST achieves very high cesium loadings (up to 1,100 curies per gallon (Ci/gal) bed volume). The design addresses the hazards associated with this material including heat management (in column and in-tank), as detailed in the thermal modeling. The CST must be size reduced for compatibility with downstream processes. The design addresses material transport into and out of the grinder and

  18. Phosphate recovery from wastewater using engineered superparamagnetic particles modified with layered double hydroxide ion exchangers.

    PubMed

    Drenkova-Tuhtan, Asya; Mandel, Karl; Paulus, Anja; Meyer, Carsten; Hutter, Frank; Gellermann, Carsten; Sextl, Gerhard; Franzreb, Matthias; Steinmetz, Heidrun

    2013-10-01

    An innovative nanocomposite material is proposed for phosphate recovery from wastewater using magnetic assistance. Superparamagnetic microparticles modified with layered double hydroxide (LDH) ion exchangers of various compositions act as phosphate adsorbers. Magnetic separation and chemical regeneration of the particles allows their reuse, leading to the successful recovery of phosphate. Based upon the preliminary screening of different LDH ion exchanger modifications for phosphate selectivity and uptake capacity, MgFe-Zr LDH coated magnetic particles were chosen for further characterization and application. The adsorption kinetics of phosphate from municipal wastewater was studied in dependence with particle concentration, contact time and pH. Adsorption isotherms were then determined for the selected particle system. Recovery of phosphate and regeneration of the particles was examined via testing a variety of desorption solutions. Reusability of the particles was demonstrated for 15 adsorption/desorption cycles. Adsorption in the range of 75-97% was achieved in each cycle after 1 h contact time. Phosphate recovery and enrichment was possible through repetitive application of the desorption solution. Finally, a pilot scale experiment was carried out by treating 125 L of wastewater with the particles in five subsequent 25 L batches. Solid-liquid separation on this scale was carried out with a high-gradient magnetic filter (HGMF).

  19. Ion Exchange Modeling Of Cesium Removal From Hanford Waste Using Spherical Resorcinol-Formaldehyde Resin

    SciTech Connect

    Aleman, S.; Hamm, L.; Smith, F.

    2007-06-27

    This report discusses the expected performance of spherical Resorcinol-Formaldehyde (RF) ion exchange resin for the removal of cesium from alkaline Hanford radioactive waste. Predictions of full scale column performance in a carousel mode are made for the Hot Commissioning, Envelope B, and Subsequent Operations waste compositions under nominal operating conditions and for perturbations from the nominal. Only the loading phase of the process cycle is addressed in this report. Pertinent bench-scale column tests, kinetic experiments, and batch equilibrium experiments are used to estimate model parameters and to benchmark the ion-exchange model. The methodology and application presented in this report reflect the expected behavior of spherical RF resin manufactured at the intermediate-scale (i.e., approximately 100 gallon batch size; batch 5E-370/641). It is generally believed that scale-up to production-scale in resin manufacturing will result in similarly behaving resin batches whose chemical selectivity is unaffected while total capacity per gram of resin may vary some. As such, the full-scale facility predictions provided within this report should provide reasonable estimates of production-scale column performance.

  20. Removal of chloride ion from aqueous solution by ZnAl-NO(3) layered double hydroxides as anion-exchanger.

    PubMed

    Lv, Liang; Sun, Peide; Gu, Zhengyu; Du, Hangeng; Pang, Xiangjun; Tao, Xiaohong; Xu, Rufeng; Xu, Lili

    2009-01-30

    The layered double hydroxides (LDHs) containing nitrate as the interlayer anion has a high anion-exchange capacity in the presence of appropriate anions. In the light of this, ZnAl-NO(3) LDHs have been employed to remove chloride ion from aqueous solution in a batch mode. The influences of conditions for chloride ion uptake, including dosage of LDHs, pH of aqueous solution, and temperature on anion-exchange have been investigated, respectively. The thermodynamic parameters including Gibbs free energy (DeltaG(0)), standard enthalpy change (DeltaH(0)), and standard entropy change (DeltaS(0)) for the process were calculated using the Langmuir constants. It was found from kinetics test that the pseudo-second order kinetics model could be used to well describe the uptake process. An E(a) value of 10.27 kJ/mol provides evidence the anion-exchange process. The explanation of anion-exchange phenomenon has also been supported by X-ray diffraction and FT-IR spectra.

  1. Calculation of the Helfferich number to identify the rate-controlling step of ion exchange for a batch process

    SciTech Connect

    Bunzl, K.

    1995-08-01

    The Helfferich number He is used frequently as a valuable criterion to decide whether for an ion exchange process film diffusion or particle diffusion of the ions is the rate-determining step. The corresponding equation given by Helfferich is restricted, however, for the boundary condition of an infinite solution volume. In the present paper, the Helfferich number is calculated also for a finite solution volume, i.e., for a typical batch process. Because the resulting equation can be solved only numerically, the results are presented in graphical form. It is also examined for which batch processes the conventional Helfferich number already yields a conservative and thus a very simple and useful estimate of the rate-determining step. Information on the kinetics of ion exchange reactions is required not only for the economic employment of synthetic ion exchangers in the industry and the laboratory but also for a better understanding of these processes in natural systems, as, e.g., the sorption of nutrient and toxic ions by the soil.

  2. In situ (1)H and (13)C MAS NMR kinetic study of the mechanism of H/D exchange for propane on zeolite H-ZSM-5.

    PubMed

    Arzumanov, Sergei S; Reshetnikov, Sergei I; Stepanov, Alexander G; Parmon, Valentin N; Freude, Dieter

    2005-10-27

    The kinetics of hydrogen (H/D) exchange between Brønsted acid sites of zeolite H-ZSM-5 and variously deuterated propanes (propane-d(8), propane-1,1,1,3,3,3-d(6), propane-2,2-d(2)) have been monitored in situ by (1)H MAS NMR spectroscopy within the temperature range of 503-556 K. The contribution of intramolecular hydrogen transfer to the H/D exchange in the adsorbed propane was estimated by monitoring the kinetics of (13)C-labeled carbon scrambling in propane-2-(13)C in situ with (13)C MAS NMR at 543-573 K. Possible mechanisms of the exchange have been verified on the basis of the analysis of the variation of protium concentration in both the methyl and the methylene groups of propane in dependence of the reaction time. The main route of the exchange consists of a direct exchange of the acidic OH groups of the zeolite with either the methyl groups or the methylene group presumably with a pentacoordinated carbonium ion intermediate. The assumption that the intramolecular H scrambling between the methyl groups and the methylene group of propane via carbenium-ion-type intermediates is the fastest process among the other possible routes does not account for the experimental kinetics of H/D exchange for propanes with different initial contents and locations of deuterium in a propane molecule. The rate constant (k(3)) for intramolecular H/D exchange between the methyl and the methylene groups is 4-5 times lower compared to those of the direct exchange of both the methyl (k(1)) and the methylene (k(2)) groups with Brønsted acid sites of the zeolite, the k(1) being ca. 1.5 times higher than k(2). At lower temperature (473 K), the exchange is slower, and the expected difference between k(1) and k(2) is more essential, k(1) = 3k(2). This accounts for earlier observed regioselectivity of the exchange for propane on H-ZSM-5 at 473 K. Faster direct exchange with the methyl groups compared to that with the methylene groups was attributed to a possible, more spatial

  3. Synthesis and Ion-Exchange Properties of Graphene Th(IV) Phosphate Composite Cation Exchanger: Its Applications in the Selective Separation of Lead Metal Ions

    PubMed Central

    Rangreez, Tauseef Ahmad; Alhogbi, Basma G.; Naushad, Mu.

    2017-01-01

    In this study, graphene Th(IV) phosphate was prepared by sol–gel precipitation method. The ion-exchange behavior of this cation-exchanger was studied by investigating properties like ion-exchange capacity for various metal ions, the effect of eluent concentration, elution behavior, and thermal effect on ion-exchange capacity (IEC). Several physicochemical properties as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) study, thermal studies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies were also carried out. The material possessed an IEC of 1.56 meq·dry·g−1 of the exchanger and was found to be nano-composite. The selectivity studies showed that the material is selective towards Pb(II) ions. The selectivity of this cation-exchanger was demonstrated in the binary separation of Pb(II) ions from mixture with other metal ions. The recovery was found to be both quantitative and reproducible. PMID:28737717

  4. Ion-exchange of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ ions from aqueous solution by Lewatit CNP 80.

    PubMed

    Pehlivan, Erol; Altun, Turkan

    2007-02-09

    Removal of trace amounts of heavy metals can be achieved by means of selective ion-exchange processes. The newly developed resins offered a high resin capacity and faster sorption kinetics for the metal ions such as Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+) ions. In the present study, the removal of Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+) ions from aqueous solutions was investigated. Experimental investigations were undertaken using the ion-exchange resin Lewatit CNP 80 (weakly acidic) and were compared with Lewatit TP 207 (weakly acidic and chelating). The optimum pH range for the ion-exchange of the above mentioned metal ions on Lewatit CNP 80 and Lewatit TP 207 were 7.0-9.0 and 4.5-5.5, respectively. The influence of pH, contact time, metal concentration and amount of ion-exchanger on the removal process was investigated. For investigations of the exchange equilibrium, different amounts of resin were contacted with a fixed volume of Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+) ion containing solution. The obtained sorption affinity sequence in the presented work was Ni(2+)>Cu(2+)>Cd(2+)>Zn(2+)>Pb(2+). The metal ion concentrations were measured by AAS methods. The distribution coefficient values for metal ions of 10(-3)M initial concentration at 0.1mol/L ionic strength show that the Lewatit CNP 80 was more selective for Ni(2+), Cu(2+) than it was for Cd(2+), Zn(2+) and Pb(2+). Langmuir isotherm was applicable to the ion-exchange process and its contents were calculated. The uptake of metal ions by the ion-exchange resins was reversible and thus has good potential for the removal of Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+) from aqueous solutions. The amount of sorbed metal ion per gram dry were calculated as 4.1, 4.6, 4.7, 4.8, and 4.7mequiv./g dry resin for Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+), respectively. Selectivity increased in the series: Cd(2+)>Pb(2+)>Cu(2+)>Ni(2+)>Zn(2+). The results obtained showed that Lewatit CNP 80 weakly acidic resin had

  5. Modeling of ion exchange expanded-bed chromatography for the purification of C-phycocyanin.

    PubMed

    Moraes, Caroline Costa; Mazutti, Marcio A; Maugeri, Francisco; Kalil, Susana Juliano

    2013-03-15

    This work is focused on the experimental evaluation and mathematical modeling of ion exchange expanded-bed chromatography for the purification of C-phycocyanin from crude fermentative broth containing Spirulina platensis cells. Experiments were carried out in different expansion degree to evaluate the process performance. The experimental breakthrough curves were used to estimate the mass transfer and kinetics parameters of the proposed model, using the Particle Swarm Optimization algorithm (PSO). The proposed model satisfactorily fitted the experimental data. The results from the model application pointed out that the increase in the initial bed height does not influence the process efficiency, however enables the operation of expanded-bed column at high volumetric flow rates, improving the productivity. It was also shown that the use of mathematical modeling was a good and promising tool for the optimization of chromatographic processes.

  6. Determination of effective capacities of ion-exchangeable materials by measuring the equilibrium conductivity.

    PubMed

    Okabe, Toshiaki; Yokoyama, Yukio

    2010-01-01

    The effective ion-exchange capacities of ion-exchange materials were determined by measuring the change in the equilibrium conductivity of a column packed with analyte. The developed instrumental method can provide effective ion-exchange capacities for both cation and anion exchangers with simple operations. The cation-exchange capacity of a weak-acid cation-exchange resin (TSKgel SuperIC-Cation column) depended on the conditioning pH and the molar concentration of the conditioning agent. Plots of effective cation-exchange capacities over the conditioning pH exhibited three inflection points, suggesting the presence of two carboxy groups and one phenolic OH group in the resin, probably due to the inherent base polymer. This method was applied to several commercial analytical columns for ion chromatography, and could provide scientifically useful results for characterizing the resin properties.

  7. Kinetics of nucleotide and metal ion interaction with G-actin.

    PubMed

    Nowak, E; Strzelecka-Golaszewska, H; Goody, R S

    1988-03-08

    The kinetics of interaction of Ca2+ ions and nucleotides with G-actin have been investigated by making use of the enhancement of 1,N6-ethenoadenosine 5'-triphosphate (epsilon ATP) fluorescence on binding to actin, the enhancement of 2-[[2-[bis(carboxymethyl)amino]-5-methylphenoxy] methyl]-6-methoxy-8-[bis(carboxymethyl)amino]quinoline (Quin-2) fluorescence on binding to Ca2+, and the sensitivity of the fluorescence of an N-(iodoacetyl)-N'-(5-sulfo-1-naphthyl)ethylenediamine (1,5-AEDANS) group on Cys-374 to metal ion binding. It is concluded that metal ion dissociation is the rate-limiting step in nucleotide dissociation (0.016 s-1 for Ca2+ at pH 7.2 and 21 degrees C) and that earlier conclusions that metal ion release is relatively fast and subsequent nucleotide release slow are incorrect. Results presented here and obtained by others on the metal ion concentration dependence of the effective rate of nucleotide exchange can be interpreted in the light of this conclusion in terms of a limiting rate which corresponds to that of metal ion release and an "apparent" dissociation constant for Ca2+ which is without direct physical significance. This apparent dissociation constant is more than 2 orders of magnitude greater than the real dissociation constant of Ca2+ from the Ca-actin-ATP complex, which was estimated to be 2 X 10(-9) M from a titration with Quin-2. Confirmation that the rate of Ca2+ release is rate limiting both in nucleotide dissociation reactions and in replacement of Ca2+ by Mg2+ was obtained with 1,5-AEDANS-actin, since both the replacement of Ca2+ by Mg2+ and the removal of Ca2+ to give the actin-ATP complex occurred at the same (slow) rate.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Electrodialysis-ion exchange for the separation of dissolved salts

    SciTech Connect

    Baroch, C.J.; Grant, P.J.

    1995-10-01

    The Department of Energy generates and stores a significant quantity of low level, high level, and mixed wastes. As some of the DOE facilities are decontaminated and decommissioned, additional and possibly different forms of wastes will be generated. A significant portion of these wastes are aqueous streams containing acids, bases, and salts, or are wet solids containing inorganic salts. Some of these wastes are quite dilute solutions, whereas others contain large quantities of nitrates either in the form of dissolved salts or acids. Many of the wastes are also contaminated with heavy metals, radioactive products, or organics. Some of these wastes are in storage because a satisfactory treatment and disposal processes have not been developed. There is considerable interest in developing processes that remove or destroy the nitrate wastes. Electrodialysis-Ion Exchange (EDIX) is a possible process that should be more cost effective in treating aqueous waste steams. This report describes the EDIX process.

  9. Advanced integrated solvent extraction and ion exchange systems

    SciTech Connect

    Horwitz, P.

    1996-10-01

    Advanced integrated solvent extraction (SX) and ion exchange (IX) systems are a series of novel SX and IX processes that extract and recover uranium and transuranics (TRUs) (neptunium, plutonium, americium) and fission products {sup 90}Sr, {sup 99}Tc, and {sup 137}Cs from acidic high-level liquid waste and that sorb and recover {sup 90}Sr, {sup 99}Tc, and {sup 137}Cs from alkaline supernatant high-level waste. Each system is based on the use of new selective liquid extractants or chromatographic materials. The purpose of the integrated SX and IX processes is to minimize the quantity of waste that must be vitrified and buried in a deep geologic repository by producing raffinates (from SX) and effluent streams (from IX) that will meet the specifications of Class A low-level waste.

  10. Electrotransportation of aniline through a perfluorosulfonate ion-exchange membrane

    SciTech Connect

    Katakura, Katsumi . Dept. of Chemical Engineering); Inaba, Minoru; Toyama, Koji; Ogumi, Zempachi; Takehara, Zenichiro . Division of Energy and Hydrocarbon Chemistry)

    1994-07-01

    Transport phenomena of aniline through Na[sup +]-, K[sup +]-, and Cs[sup +]-form of a perfluorosulfonate ion-exchange membrane, Nafion 117, under a flow of dc current, electrotransportation, were investigated. In each form, an increase in transport number of anilinium cation was observed in the current density range from 0.3 to 1.3 mA cm[sup [minus]2]. The transport number of the anilinium cation in Cs[sup +]-form was larger than that expected from the concentration and diffusion coefficient of the anilinium cation in Cs[sup +]-form Nafion. These aniline transport phenomena may be attributable to a structural change of Nafion or a decrease in hydrophobic interaction between the anilinium cation and Nafion caused by the flow of dc current.

  11. Copper ion-exchanged channel waveguides optimization for optical trapping.

    PubMed

    Reshak, A H; Khor, K N; Shahimin, M M; Murad, S A Z

    2013-08-01

    Optical trapping of particles has become a powerful non-mechanical and non-destructive technique for precise particle positioning. The manipulation of particles in the evanescent field of a channel waveguide potentially allows for sorting and trapping of several particles and cells simultaneously. Channel waveguide designs can be further optimized to increase evanescent field prior to the fabrication process. This is crucial in order to make sure that the surface intensity is sufficient for optical trapping. Simulation configurations are explained in detail with specific simulation flow. Discussion on parameters optimization; physical geometry, optical polarization and wavelength is included in this paper. The effect of physical, optical parameters and beam spot size on evanescent field has been thoroughly discussed. These studies will continue toward the development of a novel copper ion-exchanged waveguide as a method of particle sorting, with biological cell propulsion studies presently underway. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Recovery of very dilute acetic acid using ion exchange

    SciTech Connect

    Cloete, F.L.D.; Marais, A.P.

    1995-07-01

    Acetic and related acids occur in many industrial wastewaters, often mixed with several other classes of organic compounds. Acetic acid can be recovered from 1% solutions using weakly basic ion exchange resins. The acid is adsorbed by the free-base form of the resin, which can then be eluted using a slurry of lime to give a solution of calcium acetate. This solution could either be evaporated to crystallize calcium acetate or reacted with sulfuric acid to form acetic acid and gypsum. Laboratory tests of the proposed process gave product solutions of 15--20% acetic acid using pure 1% acetic acid as feed. Some measurements using a typical industrial effluent gave similar recoveries and showed that there was no initial fouling of the resins.

  13. Ion Exchange Resin Bead Decoupled High-Pressure Electroosmotic Pump

    PubMed Central

    Yang, Bingcheng; Zhang, Feifang; Liang, Xinmiao; Dasgupta, Purnendu K.; Liu, Shaorong

    2009-01-01

    We describe an electroosmotic pump (EOP) that utilizes a cation exchange resin bead as the electric field decoupler. The resin bead serves as a electrical grounding joint without fluid leakage, thus eliminating electrolytic gas interference from the flow channels. The arrangement is easy to practice from readily available components, displays a very low electrical resistance, and is capable of bearing high backpressure (at least 3200 psi). We use a silica xerogel column as the EOP element to pump water and demonstrate a complete capillary ion chromatograph (CIC), which uses a similar bead based microelectrodialytic generator (μ-EDG) to generate a KOH eluent from the pumped water. We observed good operational stability of the complete arrangement over long periods. PMID:19449862

  14. Electrodialysis-ion exchange for the separation of dissolved salts

    SciTech Connect

    Baroch, C.J.; Grant, P.J.

    1995-12-31

    The Department of Energy generates and stores a significant quantity of low level, high level, and mixed wastes. As some of the DOE facilities are decontaminated and decommissioned, additional and possibly different forms of wastes will be generated. A significant portion of these wastes are aqueous streams containing acids, bases, and salts, or are wet solids containing inorganic salts. Some of these wastes are quite dilute solutions, whereas others contain large quantities of nitrates either in the form of dissolved salts or acids. Many of the wastes are also contaminated with heavy metals, radioactive products, or organics. Some of these wastes are in storage because a satisfactory treatment and disposal processes have not been developed. This report describes the process of electrodialysis-ion exchange (EDIX) for treating aqueous wastes streams consisting of nitrates, sodium, organics, heavy metals, and radioactive species.

  15. Toroidal Electromagnetic Particle-in-Cell Code with Gyro-kinetic Electron and Fully-kinetic ion

    NASA Astrophysics Data System (ADS)

    Lin, Jingbo; Zhang, Wenlu; Liu, Pengfei; Li, Ding

    2016-10-01

    A kinetic simulation model has been developed using gyro-kinetic electron and fully-kinetic ion by removing fast gyro motion of electrons using the Lie-transform perturbation theory. A particle-in-cell kinetic code is developed based on this model in general magnetic flux coordinate systems, which is particularly suitable for simulations of toroidally confined plasma. Single particle motion and field solver are successfully verified respectively. Integrated electrostatic benchmark, for example the lower-hybrid wave (LHW) and ion Bernstein wave (IBW), shows a good agreement with theoretical results. Preliminary electromagnetic benchmark of fast wave at lower hybrid frequency range is also presented. This code can be a first-principal tool to investigate high frequency nonlinear phenomenon, such as parametric decay instability, during lower-hybrid current drive (LHCD) and ion cyclotron radio frequency heating (ICRF) with complex geometry effect included. Supported by National Special Research Program of China For ITER and National Natural Science Foundation of China.

  16. Selective adsorption of Pt ions from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion exchange resin Diaion WA21J.

    PubMed

    Shen, Shaobo; Guishen, Liang; Pan, Tonglin; He, JunZhang; Guo, Zhanchen

    2011-12-15

    Thermodynamic and kinetics studies for adsorption of Pt ions complexes from the chloride solutions obtained by leaching chlorinated spent automotive catalysts on anionic exchange resin Diaion WA21J were carried out. It was found that only Si, Pt, Rh and Pd from the solution were selectively adsorbed on the resin Diaion WA21J more strongly. The adsorption equilibrium time for Pt ions was about 20 h. The isothermal adsorption of Pt ions was found to fit Langmuir, Freundlich and DKR models. The maximum monolayer adsorption capacities Q(max) and X(m) of Pt ions on the resin based on Langmuir and DKR model were 4.85, 5.36 and 5.69 mg/g as well as 5.01, 5.63 and 5.98 mg/g for temperatures 18°C, 28°C and 40°C, respectively. The apparent adsorption energy E(ad) based on DKR model were -11.79, -11.04 and -11.04 kJ/mol for the temperatures 18°C, 28°C and 40°C, respectively. Ion exchange was the mechanism involved in the adsorption process. The adsorption of Pt ions on the resin underwent pseudo-first-order kinetic process, and the apparent adsorption activation energy E(a,1) was 12.6 kJ/mol. The intraparticle diffusion of Pt ions was a main rate-controlling step in most of time of adsorption process. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Peptide Orientation Affects Selectivity in Ion-Exchange Chromatography

    SciTech Connect

    Alpert, Andrew J.; Petritis, Konstantinos; Kangas, Lars J.; Smith, R. D.; Mechtler, Karl; Mitulovic, Goran; Mohammed, Shabaz; Heck, Albert J.

    2010-06-15

    Here we demonstrate that separation of proteolytic peptides, having the same net charge and one basic residue, is affected by their specific orientation toward the stationary phase in ion-exchange chromatography. In electrostatic repulsion-hydrophilic interaction chromatography (ERLIC) with an anion-exchange material, the C-terminus of the peptides is, on average, oriented toward the stationary phase. In cation exchange, the average peptide orientation is the opposite. Data with synthetic peptides, serving as orientation probes, indicate that in tryptic/ Lys-C peptides the C-terminal carboxyl group appears to be in a zwitterionic bond with the side chain of the C-terminal Lys/Arg residue. In effect, the side chain is then less basic than the N-terminus, accounting for the specific orientation of tryptic and Lys-C peptides. Analyses of larger sets of peptides, generated from lysates by either Lys-N, Lys-C, or trypsin, reveal that specific peptide orientation affects the ability of charged side chains, such as phosphate residues, to influence retention. Phosphorylated residues that are remote in the sequence from the binding site affect retention less than those that are closer. When a peptide contains multiple charged sites, then orientation is observed to be less rigid and retention tends to be governed by the peptide’s net charge rather than its sequence. These general observations could be of value in confirming a peptide’s identification and, in particular, phosphosite assignments in proteomics analyses. More generally, orientation accounts for the ability of chromatography to separate peptides of the same composition but different sequence.

  18. Peptide Orientation Affects Selectivity in Ion-Exchange Chromatography

    SciTech Connect

    Alpert, Andrew J.; Petritis, Konstantinos; Kangas, Lars J.; Smith, Richard D.; Mechtler, Karl; Mitulovic, Goran; Mohammed, Shabaz; Heck, Albert J.

    2010-06-15

    Here we demonstrate that separation of proteolytic peptides, having the same net charge and one basic residue, is affected by their specific orientation toward the stationary phase in ion-exchange chromatography. In electrostatic repulsion-hydrophilic interaction chromatography (ERLIC) with an anion-exchange material, the C-terminus of the peptides is, on average, oriented toward the stationary phase. In cation exchange, the average peptide orientation is the opposite. Data with synthetic peptides, serving as orientation probes, indicate that in tryptic/Lys-C peptides the C-terminal carboxyl group appears to be in a zwitterionic bond with the side chain of the C-terminal Lys/Arg residue. In effect, the side chain is then less basic than the N-terminus, accounting for the specific orientation of tryptic and Lys-C peptides. Analyses of larger sets of peptides, generated from lysates by either Lys-N, Lys-C, or trypsin, reveal that specific peptide orientation affects the ability of harged side chains, such as phosphate residues, to influence retention. Phosphorylated residues that are remote in the sequence from the binding site affect retention less than those that are closer. When a peptide contains multiple charged sites, then orientation is observed to be less rigid and retention tends to be governed by the peptide’s net charge rather than its sequence. These general observations could be of value in confirming a peptide’s identification and, in particular, phosphosite assignments in proteomics analyses. More generally, orientation accounts for the ability of chromatography to separate peptides of the same compositionbut different sequence.

  19. Kinetic Analysis of Cation Exchange in Birnessite using Time-resolved Synchrotron X-ray Diffraction

    SciTech Connect

    C Lopano; P Heaney; J Bandstra; J Post; S Brantley

    2011-12-31

    In this study, we applied time-resolved synchrotron X-ray diffraction (TRXRD) to develop kinetic models that test a proposed two-stage reaction pathway for cation exchange in birnessite. These represent the first rate equations calculated for cation exchange in layered manganates. Our previous work has shown that the substitution of K, Cs, and Ba for interlayer Na in synthetic triclinic birnessite induces measurable changes in unit-cell parameters. New kinetic modeling of this crystallographic data supports our previously postulated two-stage reaction pathway for cation exchange, and we can correlate the kinetic steps with changes in crystal structure. In addition, the initial rates of cation exchange, R ({angstrom}{sup 3} min{sup -1}), were determined from changes in unit-cell volume to follow these rate laws: R = 1.75[K{sup +}{sub (aq)}]{sup 0.56}, R = 41.1[Cs{sup +}{sub (aq)}]{sup 1.10}, R = 1.15[Ba{sup 2+}{sub (aq)}]{sup 0.50}. Thus, the exchange rates for Na in triclinic birnessite decreased in the order: Cs >> K > Ba. These results are likely a function of hydration energy differences of the cations and the preference of the solution phase for the more readily hydrated cation.

  20. Adsorption and Exchange Kinetics of Hydrophilic and Hydrophobic Phosphorus Ligands on Gold Surface

    NASA Astrophysics Data System (ADS)

    Zhuge, X. Q.; Bian, Z. C.; Luo, Z. H.; Mu, Y. Y.; Luo, K.

    2017-02-01

    The adsorption kinetics process of hydrophobic ligand (triphenylphosphine, PPh3) and hydrophilic ligand (tris(hydroxymethyl)phosphine oxide, THPO) on the surface of gold electrode were estimated by using electrical double layer capacitance (EDLC). Results showed that the adsorption process of both ligands included fast and slow adsorption processes, and the fast adsorption process could fit the first order kinetic equation of Langmuir adsorption isotherm. During the slow adsorption process, the surface coverage (θ) of PPh3 was higher than that of THPO due to the larger adsorption kinetic constant of PPh3 than that of THPO, which implied that PPh3 could replace THPO on the gold electrode. The exchange process of both ligands on the surface of gold electrode proved that PPh3 take the place of THPO by testing the variation of EDLC which promote the preparation of Janus gold, and the theoretic simulation explained the reason of ligands exchange from the respect of energy..

  1. Kinetics of DSB rejoining and formation of simple chromosome exchange aberrations

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Nikjoo, H.; O'Neill, P.; Goodhead, D. T.

    2000-01-01

    PURPOSE: To investigate the role of kinetics in the processing of DNA double strand breaks (DSB), and the formation of simple chromosome exchange aberrations following X-ray exposures to mammalian cells based on an enzymatic approach. METHODS: Using computer simulations based on a biochemical approach, rate-equations that describe the processing of DSB through the formation of a DNA-enzyme complex were formulated. A second model that allows for competition between two processing pathways was also formulated. The formation of simple exchange aberrations was modelled as misrepair during the recombination of single DSB with undamaged DNA. Non-linear coupled differential equations corresponding to biochemical pathways were solved numerically by fitting to experimental data. RESULTS: When mediated by a DSB repair enzyme complex, the processing of single DSB showed a complex behaviour that gives the appearance of fast and slow components of rejoining. This is due to the time-delay caused by the action time of enzymes in biomolecular reactions. It is shown that the kinetic- and dose-responses of simple chromosome exchange aberrations are well described by a recombination model of DSB interacting with undamaged DNA when aberration formation increases with linear dose-dependence. Competition between two or more recombination processes is shown to lead to the formation of simple exchange aberrations with a dose-dependence similar to that of a linear quadratic model. CONCLUSIONS: Using a minimal number of assumptions, the kinetics and dose response observed experimentally for DSB rejoining and the formation of simple chromosome exchange aberrations are shown to be consistent with kinetic models based on enzymatic reaction approaches. A non-linear dose response for simple exchange aberrations is possible in a model of recombination of DNA containing a DSB with undamaged DNA when two or more pathways compete for DSB repair.

  2. Kinetics of DSB rejoining and formation of simple chromosome exchange aberrations

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Nikjoo, H.; O'Neill, P.; Goodhead, D. T.

    2000-01-01

    PURPOSE: To investigate the role of kinetics in the processing of DNA double strand breaks (DSB), and the formation of simple chromosome exchange aberrations following X-ray exposures to mammalian cells based on an enzymatic approach. METHODS: Using computer simulations based on a biochemical approach, rate-equations that describe the processing of DSB through the formation of a DNA-enzyme complex were formulated. A second model that allows for competition between two processing pathways was also formulated. The formation of simple exchange aberrations was modelled as misrepair during the recombination of single DSB with undamaged DNA. Non-linear coupled differential equations corresponding to biochemical pathways were solved numerically by fitting to experimental data. RESULTS: When mediated by a DSB repair enzyme complex, the processing of single DSB showed a complex behaviour that gives the appearance of fast and slow components of rejoining. This is due to the time-delay caused by the action time of enzymes in biomolecular reactions. It is shown that the kinetic- and dose-responses of simple chromosome exchange aberrations are well described by a recombination model of DSB interacting with undamaged DNA when aberration formation increases with linear dose-dependence. Competition between two or more recombination processes is shown to lead to the formation of simple exchange aberrations with a dose-dependence similar to that of a linear quadratic model. CONCLUSIONS: Using a minimal number of assumptions, the kinetics and dose response observed experimentally for DSB rejoining and the formation of simple chromosome exchange aberrations are shown to be consistent with kinetic models based on enzymatic reaction approaches. A non-linear dose response for simple exchange aberrations is possible in a model of recombination of DNA containing a DSB with undamaged DNA when two or more pathways compete for DSB repair.

  3. High speed ion exchange techniques for neptunium, plutonium, and uranium impurity assays

    SciTech Connect

    Maxwell, III, S L

    1988-01-01

    Rapid, efficient ion exchange separations can be performed 10 to 15 times faster than conventional flow rates by using a modified commercial vacuum extraction system and small particle resins. At the Savannah River Plant (SRP), these techniques are being applied to make ion exchange separation techniques more rapid and thus more practical for routine laboratory applications.

  4. Modeling of Crystalline Silicotitanate Ion Exchange Columns Using Experimental Data from SRS Simulated Waste

    SciTech Connect

    Walker, D.D.

    1999-03-15

    Non-elutable ion exchange using crystalline silicotitanate is being considered for removing cesium from Savannah River Site radioactive waste. The construction cost of this process depends strongly on the size of the ion exchange column required to meet product specifications.

  5. Kinetically controlled patterning of highly cross-linked phosphonium photopolymers using simple anion exchange.

    PubMed

    Guterman, Ryan; Gillies, Elizabeth R; Ragogna, Paul J

    2015-05-12

    A phosphonium salt possessing three methacrylate groups has been incorporated into a photopolymeric system to generate highly cross-linked polyelectrolyte networks. Emergent chemical and physical properties in the polymers were observed and attributed to the tandem increase in cross-link density and ion-content upon incorporation of the self-cross-linking cation. Anion-exchange with bis(trifluoromethylsulfonyl)imide or dodecylbenzenesulfonate resulted in significant differences in wettability and ion-exchange behavior. The passivating effects of dodecylbenzenesulfonate were utilized to selectively pattern fluorescein dye into the polymer network, highlighting a new patterning procedure using ionic-bond forming reactions.

  6. Thermodynamic and kinetic characterization of H-D exchange in Pd and Pd alloys.

    SciTech Connect

    Luo, Weifang

    2010-09-01

    A Sieverts apparatus coupled with an RGA is an effective method to detect composition variations during isotopic exchange. This experimental setup provides a powerful tool for the thermodynamic and kinetic characterization of H-D isotope exchange on metals and alloys. H-D exchange behavior during absorption and desorption in the plateau region in Pd have been investigated and reported here. It was found that in the plateau region of H-D-Pd system the equilibrium pressures are between those of H2-Pd and D2-Pd for both absorption and desorption and the equilibrium pressures are higher when the fractions of D in the Pd are higher. Adding a dose of gas H2 (or D2) to Pd-D (or Pd-H) system results in releasing of gas D2 and HD (or H2 and HD) in {beta}-phase of Pd-D (or {beta}-phase of Pd-H), but this does not happen in the plateau region. The equilibrium constants have been determined during exchange and it was found that they agree well with the calculated values reported in literature. The separation factor {alpha} values during exchange have been measured and compared with the literature values. The exchange rates have been determined from the exchange profiles and a first order kinetic model for the exchange of H-D-Pd systems has been employed for the analysis. The exchange activation energies for both directions, H2+PdD and D2+PdH, have been determined.

  7. Latex-coated polymeric monolithic ion-exchange stationary phases. 2. Micro-ion chromatography.

    PubMed

    Zakaria, Philip; Hutchinson, Joseph P; Avdalovic, Nebojsa; Liu, Yan; Haddad, Paul R

    2005-01-15

    Latex-coated monolithic polymeric stationary phases are used for micro-ion chromatography (mu-IC) of inorganic anions. Monolithic columns were prepared by the in situ polymerization of butyl methacrylate, ethylene dimethacrylate, and 2-acrylamido-2-methyl-1-propanesulfonic acid within fused-silica capillaries of varying internal diameters. Introduction of ion-exchange sites was achieved by coating the anionic polymeric monolith with either Dionex AS10 or Dionex AS18 quaternary ammonium functionalized latex particles to give total ion-exchange capacities in the range 9-24 nequiv for a 30-cm column. The resultant mu-IC columns were used for the separation of anionic analytes using chloride or acetate as the eluent-competing ion and direct UV spectrophotometric detection at 195 nm or using hydroxide as the eluent-competing ion and suppressed or nonsuppressed contactless conductivity detection. Separation efficiencies of 13,000 plates/m were observed (for iodate), and separation efficiency was maintained for large increases in flow rate (up to 42 microL/min, corresponding to a linear flow velocity of 18.5 mm/s), enabling highly reproducible, rapid separations to be achieved (seven analyte anions in less than 2 min). Use of a hollow fiber micromembrane suppressor enabled effective suppression of hydroxide eluents over the range 0.5-5.0 mM, thereby permitting suppressed conductivity detection to be performed. However, the relatively large size of the suppressor resulted in reduced separation efficiencies (e.g., 5400 plates/m for iodate). Detection limits obtained with suppressed conductivity detection were in the range 0.4-1.2 microM.

  8. Nanomaterials-Enhanced Electrically Switched Ion Exchange Process for Water Treatment

    SciTech Connect

    Lin, Yuehe; Choi, Daiwon; Wang, Jun; Bontha, Jagannadha R.

    2009-01-01

    The objective of our work is to develop an electrically switched ion exchange (ESIX) system based on conducting polymer/carbon nanotube (CNT) nanocomposites as a new and cost-effective approach for removal of radioactive cesium, chromate, and perchlorate from contaminated groundwater. The ESIX technology combines ion exchange and electrochemistry to provide a selective, reversible method for the removal of target species from wastewater. In this technique, an electroactive ion exchange layer is deposited on a conducting substrate, and ion uptake and elution are controlled directly by modulation of the potential of the layer. ESIX offers the advantages of highly-efficient use of electrical energy combined with no secondary waste generation. Recently, we have improved upon the ESIX process by modifying the conducting substrate with carbon nanotubes prior to the deposition of the electroactive ion exchanger. The nanomaterial-based electroactive ion exchange technology will remove cesium-137, chromate, and perchlorate rapidly from wastewater. The high porosity and high surface area of the electroactive ion exchange nanocomposites results in high loading capacity and minimize interferences for non-target species. Since the ion adsorption/desorption is controlled electrically without generating a secondary waste, this electrically active ion exchange process is a green process technology that will greatly reduce operating costs.

  9. Probing peptide fragment ion structures by combining sustained off-resonance collision-induced dissociation and gas-phase H/D exchange (SORI-HDX) in Fourier transform ion-cyclotron resonance (FT-ICR) instruments.

    PubMed

    Somogyi, Arpád

    2008-12-01

    The usefulness of gas-phase H/D exchange is demonstrated to probe heterogeneous fragment and parent ion populations. Singly and multiply protonated peptides/proteins were fragmented by using sustained off-resonance irradiation collision-induced dissociation (SORI-CID). The fragments and the surviving precursor ions then all undergo H/D exchange in the gas-phase with either D(2)O or CD(3)OD under the same experimental conditions. Usually, 10 to 60 s of reaction time is adequate to monitor characteristic differences in the H/D exchange kinetic rates. These differences are then correlated to isomeric ion structures. The SORI-HDX method can be used to rapidly test fragment ion structures and provides useful insights into peptide fragmentation mechanisms.

  10. Electrical resistance and transport numbers of ion-exchange membranes used in electrodialytic soil remediation

    SciTech Connect

    Hansen, H.K.; Ottosen, L.M.; Villumsen, A.

    1999-08-01

    Electrodialytic soil remediation is a recently developed method to decontaminate heavy metal polluted soil using ion-exchange membranes. In this method one side of the ion-exchange membrane is in direct contact with the polluted soil. It is of great importance to known if this contact with the soil causes damage to the membrane. This work presents the result of transport number and electrical resistance measurements done on four sets of ion-exchange membranes (Ionics, Inc CR67 HMR412 cation-exchange membranes and Ionics, Inc AR204 SXZR anion-exchange membranes), which have been used in four different electrodialytic soil remediation experiments. The experiments showed that after the use in electrodialytic soil remediation, the ion-exchange membranes had transport numbers in the same magnitude as new membranes. The electrical resistance for six membranes did not differ from that of new membranes, whereas two membranes showed a slightly increased resistance.

  11. Intermediate-Scale Ion Exchange Removal of Cesium and Technetium from Hanford Tank 241-AN-102

    SciTech Connect

    King, W.D.

    2001-02-15

    Ion exchange tests have been completed at the Savannah River Technology Center for British Nuclear Fuels Limited, Inc. as part of the Hanford River Protection Project. Radioactive cesium and technetium (pertechnetate form only) were removed by ion exchange from a sample of Envelope C salt solution from Hanford Tank 241-AN-102 (sample volume: approximately 17 L at 4.8 M Na plus). The original sample was diluted and subjected to strontium/transuranics (Sr/TRU) precipitation and filtration processes before ion exchange processing was performed. Batch contact and column tests for the ion exchange removal of cesium and technetium were then completed on the Sr/TRU-decontaminated product. Previous ion exchange tests were conducted on a smaller portion (0.5 L) of the Tank 241-AN-102 supernate sample, which had been similarly pretreated, and the results were reported in a separate document.

  12. Intermediate-Scale Ion Exchange Removal of Cesium and Technetium from Hanford Tank 241-AN-102

    SciTech Connect

    King, W.D.

    2001-09-10

    Ion exchange tests have been completed at the Savannah River Technology Center for British Nuclear Fuels Limited, Inc. as part of the Hanford River Protection Project. Radioactive cesium and technetium (pertechnetate form only) were removed by ion exchange from a sample of Envelope C salt solution from Hanford Tank 241-AN-102 (sample volume: approximately 18 L at 4.8 M Na plus). The original sample was diluted and subjected to strontium/transuranics (Sr/TRU) precipitation and filtration processes before ion exchange processing was performed. Batch contact and column tests for the ion exchange removal of cesium and technetium were then completed on the Sr/TRU-decontaminated product. Previous ion exchange tests were conducted on a smaller portion (0.5 L) of the Tank 241-AN-102 supernate sample, which had been similarly pretreated, and the results were reported in a separate document.

  13. Ion Exchange Media for Reduction of Liquid Radwaste in Commercial Power Plants

    SciTech Connect

    Yarnell, P.A.; Tavares, A.

    2008-07-01

    Ion exchange resins currently make up as much as one-half of all radioactive waste generated by commercial nuclear power plants. A major challenge is reduction of the quantity of ion exchange media requiring disposal. Although the amount of spent ion exchange resins disposed has decreased year after year, a new urgency has arisen with the pending closure of a major disposal site in 2008. This paper explores whether ion exchange resins also can be used to potentially reduce radioactive liquid waste volumes and / or limit them to Class A wastes only. Source term reduction and minimization of manpower exposure to radioactivity are other important goals. Specialty ion exchange products may help to achieve source term reduction of certain radionuclides. Some established operations, data, and process concepts are presented to address these critical issues encountered in liquid radwaste management. (authors)

  14. Ion-exchange selectivities of periderm and cuticular membranes toward alkali cations

    SciTech Connect

    Ersoz, M.; Duncan, H.J.

    1994-08-01

    The ion-exchange selectivities of lithium, sodium, potassium, and cesium on isolated potato periderm (Solanum tuberosum) and pear fruit cuticular membranes were investigated; the general order of preference both for cation selectivities and ion-exchange capacities was lithium > sodium > potassium > cesium. The potato periderm and pear fruit cuticular membranes exhibited a behavior typical of ion-exchange resins of the weak acid type. At constant pH 7, the ion-exchange capacities of periderm and cuticular membranes increased with hydrated ionic radius, and also with increasing pH and neutral salt concentration, and decreased with crystal ionic radius. Counterion selectivities also exhibited the same behavior. The ion-exchange properties are discussed in terms of the structure and function of potato periderm and pear fruit cuticular membranes.

  15. Comparison of monomode KTiOPO4 waveguide formed by C3+ ion implantation and Rb+ ion exchange

    NASA Astrophysics Data System (ADS)

    Cui, Xiao-Jun; Wang, Liang-Ling

    2017-02-01

    In this work, we report on the formation and characterization of monomode KTiOPO4 waveguide at 1539 nm by 6.0 MeV C3+ ion implantation with the dose of 2×1015 ions/cm2 and Rb+-K+ ion exchange, respectively. The relative intensity of light as a function of effective refractive index of TM modes at 633 nm and 1539 nm for KTiOPO4 waveguide formed by two different methods were compared with the prism coupling technique. The refractive index (nz) profile for the ion implanted waveguide was reconstructed by reflectivity calculation method, and one for the ion exchanged waveguide was by inverse Wentzel-Kramers-Brillouin. The nuclear energy loss versus penetration depth of the C3+ ions implantation into KTiOPO4 was simulated using the Stopping Range of Ions in Matter software. The Rutherford Backscattering Spectrometry spectrum of KTiOPO4 waveguide was analyzed after ions exchanged. The results showed that monomode waveguide at 1539 nm can be formed by ion implantation and Rb+ -K+ ion exchange, respectively.

  16. Preparation and characterization of (St-DVB-MAA) ion exchange resins

    NASA Astrophysics Data System (ADS)

    Jiang, Shanquan; Sun, Xiangwei; Ling, Lixing; Wang, Shumin; Wu, Wufeng; Cheng, Shihong; Hu, Yue; Zhong, Chunyan

    2017-08-01

    In this paper, used polyvinyl alcohol as dispersing agent, Benzoyl peroxide as initiator of polymerization, Divinyl benzene as cross-linking agent, Styrene and 2-Methylpropenoic acid as monomer, ion exchange resin (copolymer of St-DVB-MAA)were prepared by suspension polymerization on 80°C. The structures, components and properties of the prepared composite micro gels were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA). The experiment of ion exchange was conducted by resin to deal with copper ions in the solution. The result showed that performance of the ion exchange capacity was excellent, which impacted by pH.

  17. Ion mobility spectrometry-hydrogen deuterium exchange mass spectrometry of anions: part 1. Peptides to proteins.

    PubMed

    Donohoe, Gregory C; Khakinejad, Mahdiar; Valentine, Stephen J

    2015-04-01

    Ion mobility spectrometry (IMS) coupled with hydrogen deuterium exchange (HDX)-mass spectrometry (MS) has been used to study the conformations of negatively-charged peptide and protein ions. Results are presented for ion conformers of angiotensin 1, a synthetic peptide (SP), bovine insulin, ubiquitin, and equine cytochrome c. In general, the SP ion conformers demonstrate a greater level of HDX efficiency as a greater proportion of the sites undergo HDX. Additionally, these ions exhibit the fastest rates of exchange. Comparatively, the angiotensin 1 ions exhibit a lower rate of exchange and HDX level presumably because of decreased accessibility of exchange sites by charge sites. The latter are likely confined to the peptide termini. Insulin ions show dramatically reduced HDX levels and exchange rates, which can be attributed to decreased conformational flexibility resulting from the disulfide bonds. For the larger ubiquitin and protein ions, increased HDX is observed for larger ions of higher charge state. For ubiquitin, a conformational transition from compact to more elongated species (from lower to higher charge states) is reflected by an increase in HDX levels. These results can be explained by a combination of interior site protection by compact conformers as well as decreased access by charge sites. The elongated cytochrome c ions provide the largest HDX levels where higher values correlate with charge state. These results are consistent with increased exchange site accessibility by additional charge sites. The data from these enhanced IMS-HDX experiments are described in terms of charge site location, conformer rigidity, and interior site protection.

  18. Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 1. Peptides to Proteins

    NASA Astrophysics Data System (ADS)

    Donohoe, Gregory C.; Khakinejad, Mahdiar; Valentine, Stephen J.

    2015-04-01

    Ion mobility spectrometry (IMS) coupled with hydrogen deuterium exchange (HDX)-mass spectrometry (MS) has been used to study the conformations of negatively-charged peptide and protein ions. Results are presented for ion conformers of angiotensin 1, a synthetic peptide (SP), bovine insulin, ubiquitin, and equine cytochrome c. In general, the SP ion conformers demonstrate a greater level of HDX efficiency as a greater proportion of the sites undergo HDX. Additionally, these ions exhibit the fastest rates of exchange. Comparatively, the angiotensin 1 ions exhibit a lower rate of exchange and HDX level presumably because of decreased accessibility of exchange sites by charge sites. The latter are likely confined to the peptide termini. Insulin ions show dramatically reduced HDX levels and exchange rates, which can be attributed to decreased conformational flexibility resulting from the disulfide bonds. For the larger ubiquitin and protein ions, increased HDX is observed for larger ions of higher charge state. For ubiquitin, a conformational transition from compact to more elongated species (from lower to higher charge states) is reflected by an increase in HDX levels. These results can be explained by a combination of interior site protection by compact conformers as well as decreased access by charge sites. The elongated cytochrome c ions provide the largest HDX levels where higher values correlate with charge state. These results are consistent with increased exchange site accessibility by additional charge sites. The data from these enhanced IMS-HDX experiments are described in terms of charge site location, conformer rigidity, and interior site protection.

  19. Aspartate beta-decarboxylase from Alcaligenes faecalis: carbon-13 kinetic isotope effect and deuterium exchange experiments

    SciTech Connect

    Rosenberg, R.M.; O'Leary, M.H.

    1985-03-26

    The authors have measured the /sup 13/C kinetic isotope effect at pH 4.0, 5.0, 6.0, and 6.5 and in D/sub 2/O at pH 5.0 and the rate of D-H exchange of the alpha and beta protons of aspartic acid in D/sub 2/O at pH 5.0 for the reaction catalyzed by the enzyme aspartate beta-decarboxylase from Alcaligenes faecalis. The /sup 13/C kinetic isotope effect, with a value of 1.0099 +/- 0.0002 at pH 5.0, is less than the intrinsic isotope effect for the decarboxylation step, indicating that the decarboxylation step is not entirely rate limiting. The authors have been able to estimate probable values of the relative free energies of the transition states of the enzymatic reaction up to and including the decarboxylation step from the /sup 13/C kinetic isotope effect and the rate of D-H exchange of alpha-H. The pH dependence of the kinetic isotope effect reflects the pKa of the pyridine nitrogen of the coenzyme pyridoxal 5'-phosphate but not that of the imine nitrogen. A mechanism is proposed for the exchange of aspartate beta-H that is consistent with the stereochemistry suggested earlier.

  20. Regeneration of spent powdered activated carbon saturated with inorganic ions by cavitation united with ion exchange method.

    PubMed

    Li, Gang; Gao, Hong; Li, Yansheng; Yang, Huixin

    2011-06-01

    Using ion exchange resin as transfer media, regenerate powdered activated carbon (PAC) adsorbed inorganic ions by cavitation to enhance the transfer; we studied how the regeneration time and the mass ratio of resin and PAC influence the regeneration rate respectively through re-adsorption. The result showed that the effective regeneration of PAC saturated with inorganic ions was above 90% using ion exchange resin as media and transfer carrier, the quantity of PAC did not reduced but activated in the process. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.