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1

ION EXCHANGE  

EPA Science Inventory

The IONEX program's name is a contraction of "ion exchange." The IONEX program performs calculations related to removing radium and/or uranium from water with the ion exchange process. IONEX provides a quick method of calculating whether a proposed ion exchange process will m...

2

Composite ion exchange materials  

SciTech Connect

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.

Amarasinghe, S.; Zook, L.; Leddy, J. [Univ. of Iowa, Iowa City, IA (United States)

1994-12-31

3

Ion microprobe analysis of oxygen isotope ratios in granulite facies magnetites: diffusive exchange as a guide to cooling history  

NASA Astrophysics Data System (ADS)

Ion microprobe analysis of magnetites from the Adirondack Mountains, NY, yields oxygen isotope ratios with spatial resolution of 2 8 ?m and precision in the range of 1‰ (1 sigma). These analyses represent 11 orders of magnitude reduction in sample size compared to conventional analyses on this material and they are the first report of routinely reproducible precision in the 1 per mil range for analysis of ?18O at this scale. High precision micro-analyses of this sort will permit wide-ranging new applications in stable isotope geochemistry. The analyzed magnetites form nearly spherical grains in a calcite matrix with diopside and monticellite. Textures are characteristic of granulite facies marbles and show no evidence for retrograde recrystallization of magnetite. Magnetites are near to Fe3O4 in composition, and optically and chemically homogeneous. A combination of ion probe plus conventional BrF5 analysis shows that individual grains are homogeneous with ?18O=8.9±1‰ SMOW from the core to near the rim of 0.1 1.2 mm diameter grains. Depth profiling into crystal growth faces of magnetites shows that rims are 9‰ depleted in ?18O. These low ?18O values increase in smooth gradients across the outer 10 ?m of magnetite rims in contact with calcite. These are the sharpest intracrystalline gradients measured to date in geological materials. This discovery is confirmed by bulk analysis of 150 350 ?m diameter magnetites which average 1.2‰ lower in ?18O than coarse magnetites due to low ?18O rims. Conventional analysis of coexisting calcite yields °18O=18.19, suggesting that bulk ?18O (Cc-Mt)=9.3‰ and yielding an apparent equilibration “temperature” of 525° C, over 200° C below the temperature of regional metamorphism. Consideration of experimental diffusion data and grain size distribution for magnetite and calcite suggests two contrasting cooling histories. The data for oxygen in calcite under hydrothermal conditions at high P(H2O) indicates that diffusion is faster in magnetite and modelling of the low ?18O rims on magnetite would suggest that the Adirondacks experienced slow cooling after Grenville metamorphism, followed by a brief period of rapid cooling, possibly related to uplift. Conversely, the data for calcite at low P(H2O) show slower oxygen diffusion than in magnetite. Modelling based on these data is consistent with geochronology that shows slow cooling through the blocking temperature of both minerals, suggesting that the low ?18O rims form by exchange with late, low temperature fluids similar to those that infiltrated the rock to serpentinize monticellite and which infiltrated adjacent anorthosite to form late calcite veinlets. In either case, the ion microprobe results indicate that two distinct events are recorded in the post-metamorphic exchange history of these magnetites. Recognition of these events is only possible through microanalysis and has important implications for geothermometry.

Valley, John W.; Graham, Colin M.

1991-03-01

4

Biological Ion Exchanger Resins  

PubMed Central

Utilizing Escherichia coli as the prototype of an ion-accumulating cell, the ion exchange isotherm is introduced as a concise method of characterizing biological ion exchange events. The ion exchange isotherm for the alkali cation exchange, K ? Na, is described. The total charge profile of this bacterium is compiled and compared for bacteria in the Na form and in the K form. Macromolecule fixed charge was found to provide 80% of the counter ions that pair with potassium. Therefore, in its physiological state, 80% of the cell potassium in E. coli is associated with an ion exchange site on a macromolecule. The primary cation exchange sites are found to be about equally divided between carboxylate and phosphate sites indicating that E. coli is a bifunctional resin with respect to cation exchange. During substrate-dependent cation accumulation (“active transport”), phosphate esters and organic acids were shown to accumulate. One may conclude that the role of intermediate metabolism in “active transport” is to increase the ion exchange capacity of the biological resin by the production of charged metabolites that sorb to the framework of the resin. PMID:4943652

Damadian, Raymond

1971-01-01

5

Ion exchange phenomena  

SciTech Connect

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).

Bourg, I.C.; Sposito, G.

2011-05-01

6

Charge exchange molecular ion source  

DOEpatents

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.

Vella, Michael C.

2003-06-03

7

Ion exchange technology assessment report  

SciTech Connect

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.

Duhn, E.F.

1992-01-01

8

Ion exchange technology assessment report  

SciTech Connect

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.

Duhn, E.F.

1992-12-31

9

Ion-exchange hollow fibers  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

10

Ion-exchange hollow fibers  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

11

Ion-exchange hollow fibers  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

12

Ion exchange - Simulation and experiment  

NASA Technical Reports Server (NTRS)

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.

Herrmann, Cal C.; Finn, John E.

1991-01-01

13

Cesium-specific phenolic ion exchange resin  

DOEpatents

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.

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

1995-08-15

14

Cesium-specific phenolic ion exchange resin  

DOEpatents

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.

Bibler, Jane P. (Aiken, SC); Wallace, Richard M. (Aiken, SC)

1995-01-01

15

Vitrification of ion exchange resins  

DOEpatents

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.

Cicero-Herman, Connie A. (Aiken, SC); Workman, Rhonda Jackson (North Augusta, SC)

2001-01-01

16

Ion microprobe analysis of oxygen isotope ratios in quartz from Skye granite: healed micro-cracks, fluid flow, and hydrothermal exchange  

Microsoft Academic Search

Quartz grains in hydrothermally altered granites from the Isle of Skye are highly heterogeneous and not equilibrated in oxygen isotope ratio at the 20 mum scale. Ion microprobe analysis of one grain shows a gradient of 130\\/00 over 400 mum and a greater range in delta 18O than all quartz previously analyzed on the Isle of Skye. Other crystals from

J. W. Valley; Colin M. Graham

1996-01-01

17

Ion Exchange Chromatography  

NSDL National Science Digital Library

This website contains an ion chromatography simulator that can be run online or can be downloaded. The simulator focuses on separations of proteins using Ion Chromatography. Also included is linked reference information, an example of a homework assignment using the simulator, and some information on protein structures.

18

Phosphonic acid based ion exchange resins  

DOEpatents

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.

Horwitz, E. Philip (Naperville, IL); Alexandratos, Spiro D. (Knoxville, TN); Gatrone, Ralph C. (Naperville, IL); Chiarizia, Ronato (Oak Park, IL)

1996-01-01

19

Phosphonic acid based ion exchange resins  

DOEpatents

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.

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

1996-07-23

20

Grafted methylenediphosphonate ion exchange resins  

DOEpatents

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.

Trochimcznk, Andrzej W. (Knoxville, TN); Gatrone, Ralph C. (Plymouth, PA); Alexandratos, Spiro (Knoxville, TN); Horwitz, E. Philip (Naperville, IL)

1998-01-27

21

Grafted methylenediphosphonate ion exchange resins  

DOEpatents

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.

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

1997-04-08

22

Grafted methylenediphosphonate ion exchange resins  

DOEpatents

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.

Trochimcznk, Andrzej W. (Knoxbille, TN); Gatrone, Ralph C. (Plymouth, PA); Alexandratos, Spiro (Knoxville, TN); Horwitz, E. Philip (Naperville, IL)

1997-01-01

23

Ion microprobe analysis of oxygen isotope ratios in quartz from Skye granite: healed micro-cracks, fluid flow, and hydrothermal exchange  

Microsoft Academic Search

Quartz grains in hydrothermally altered granites from the Isle of Skye are highly heterogeneous and not equilibrated in oxygen\\u000a isotope ratio at the 20??m scale. Ion microprobe analysis of one grain shows a gradient of 13‰ over 400??m and a greater range\\u000a in ?\\u000a 18O than all quartz previously analyzed on the Isle of Skye. Other crystals from the same

John W. Valley; Colin M. Graham

1996-01-01

24

Ion Exchange and Liquid Column Chromatography.  

ERIC Educational Resources Information Center

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)

Walton, Harold F.

1980-01-01

25

Pharmaceutical Applications of Ion-Exchange Resins  

ERIC Educational Resources Information Center

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…

Elder, David

2005-01-01

26

Ion exchange purification of scandium  

DOEpatents

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.

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

1990-10-23

27

Ion exchange purification of scandium  

DOEpatents

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.

Herchenroeder, Laurie A. (Noblesville, IN); Burkholder, Harvey R. (Ames, IA)

1990-10-23

28

Facility produced charge-exchange ions  

NASA Technical Reports Server (NTRS)

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.

Carruth, M. R., Jr.

1981-01-01

29

Ion Exchange Formation via Sulfonated Bicomponent Nonwovens  

NASA Astrophysics Data System (ADS)

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.

Stoughton, Hannah L.

30

Using Ion Exchange Chromatography to Separate and Quantify Complex Ions  

ERIC Educational Resources Information Center

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"…

Johnson, Brian J.

2014-01-01

31

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...

32

Using Ion Exchange Chromatography to Separate Proteins  

NSDL National Science Digital Library

This activity website, hosted by the National Health Museum Activities Exchange, explores protein purification using ion chromatography. Students will separate a positively charged lysozyme from a negatively charged albumin at a neutral pH using ion exchange chromatography. The site includes information for the teacher, instructions and follow-up questions for students, and a list of supplies.

Ellyn A. Daugherty

33

Titania bound sodium titanate ion exchanger  

DOEpatents

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.

DeFilippi, Irene C. G. (Palatine, IL); Yates, Stephen Frederic (Rolling Meadows, IL); Shen, Jian-Kun (Lake Zurich, IL); Gaita, Romulus (Morton Grove, IL); Sedath, Robert Henry (Bensenville, IL); Seminara, Gary Joseph (Chicago, IL); Straszewski, Michael Peter (Novi, MI); Anderson, David Joseph (Oak Lawn, IL)

1999-03-23

34

Ion exchange in photonic glasses  

NASA Astrophysics Data System (ADS)

Theoretical descriptions of ion transport processes involving real glass systems are often idealized. Below their glass transition temperatures, ion exchange glasses are usually assumed to have a spatially rigid network with only monovalent cations as the mobile components. The effect of one cation's movement on another is presumed to be purely electrostatic. This thesis shows site relaxation can exist transmitting into additional cross interactions between cations for certain oxide glasses. The oxide glasses are categorized by cation environments, being non-bridging oxygen (NBO) rich and bridging oxygen (BO) rich. Macroscopically, the relaxation is manifest by time dependent interdiffusion and radiotracer diffusion coefficients in a BO rich glass. The interdiffusion coefficient for a NBO rich glass is found to be time independent. By using irreversible thermodynamics, phenomenological expressions for the diffusion process can be written. However, it is not immediately obvious how to connect proper theoretical treatment of the more complex relaxing system to experiment. In contrast, the traditional approach can still be applied if the appropriate selection and determination of phenomenological coefficients are made at a fixed diffusion time. We demonstrate the novel approach of using dilute co-tracer diffusion in conjunction with dilute single tracer diffusion to experimentally determine the appropriate phenomenological coefficients to use for ionic diffusion in a relaxing glass system. Non-reciprocal cross phenomenological coefficients are realized for the relaxing BO rich glass. To our knowledge this represents the first known measurement of cross phenomenological coefficients for dilute cation diffusion in glass. Concentration dependence is accounted for by using a series of uniform samples with different compositions. Time dependence is measured by using different diffusion times. The interdiffusion coefficient describing non-dilute ion exchange is defined in terms of the phenomenological coefficients (including cross coefficients). The corresponding thermodynamic term, relating dilute parameters to non-dilute ones, is measured using the salt bath equilibrium technique. In our time dependent system, the thermodynamic term is measured in the base samples represented by zero diffusion time. Thus, the thermodynamic term is better suited for short diffusion times and less suited for longer diffusion times.

Poling, Steven Andrew

35

Alkali ion exchange in ?-irradiated glasses  

NASA Astrophysics Data System (ADS)

The alkali ion exchange of ?-irradiated glasses was investigated using the structural energy barrier model for ion exchange of glasses. It is shown that rates of alkali ion exchange have a non-Arrhenius behaviour depending both on irradiation dose and dose rate. For this reason some effects cannot be simulated by external irradiation and require in situ measurements. Higher doses and dose rates of ?-radiation lead to increased ion exchange rates. Significant changes occur in the activation energies demonstrating a many times decrease depending on glass composition. Radiation-induced changes are higher at relatively low temperatures being diminished by increased glass temperature. Numerical estimations show that changes in alkali ion exchange kinetics occur below the glass network damaging doses.

Ojovan, Michael I.; Lee, William E.

2004-12-01

36

Ion exchanger from chemically modified banana leaves.  

PubMed

Cation exchangers from chemically modified banana leaves have been prepared. Banana leaves were treated with different molarities of KMnO4 and cross linked with epichlorohydrin and their effect on metal ion adsorption was investigated. Phosphorylation of chemically modified banana leaves was also studied. The metal ion uptake by these modified banana leaves was clarified. Effect of different varieties, e.g. activation of produced cation exchanger, concentration of metal ions was also investigated. Characterization of the prepared ion exchangers by using infrared and thermal analysis was also taken in consideration. PMID:23768590

El-Gendy, Ahmed A; Mohamed, Samar H; Abd-Elkader, Amal H

2013-07-25

37

21 CFR 173.21 - Perfluorinated ion exchange membranes.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 false Perfluorinated ion exchange membranes. 173.21 Section...Treatment § 173.21 Perfluorinated ion exchange membranes. Substances identified...a) of this section may be safely used as ion exchange membranes intended for use...

2012-04-01

38

21 CFR 173.21 - Perfluorinated ion exchange membranes.  

Code of Federal Regulations, 2014 CFR

... 2014-04-01 false Perfluorinated ion exchange membranes. 173.21 Section...Treatment § 173.21 Perfluorinated ion exchange membranes. Substances identified...a) of this section may be safely used as ion exchange membranes intended for use...

2014-04-01

39

21 CFR 173.21 - Perfluorinated ion exchange membranes.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 false Perfluorinated ion exchange membranes. 173.21 Section...Treatment § 173.21 Perfluorinated ion exchange membranes. Substances identified...a) of this section may be safely used as ion exchange membranes intended for use...

2011-04-01

40

21 CFR 173.21 - Perfluorinated ion exchange membranes.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Perfluorinated ion exchange membranes. 173.21 Section...Treatment § 173.21 Perfluorinated ion exchange membranes. Substances identified...a) of this section may be safely used as ion exchange membranes intended for use...

2013-04-01

41

Development of novel fuel ion ratio diagnostic techniques.  

PubMed

To overcome the challenge of measuring the fuel ion ratio in the core (?<0.3) of ITER, a coordinated effort aiming at developing diagnostic techniques has been initiated. The investigated techniques are novel uses or further development of existing methods such as charge exchange recombination spectrometry, neutron spectrometry, and collective Thomson scattering. An overview of the work on the three diagnostic techniques is presented. PMID:21033847

Korsholm, S B; Stejner, M; Conroy, S; Ericsson, G; Gorini, G; Tardocchi, M; von Hellermann, M; Jaspers, R J E; Lischtschenko, O; Delabie, E; Bindslev, H; Furtula, V; Leipold, F; Meo, F; Michelsen, P K; Moseev, D; Nielsen, S K; Salewski, M

2010-10-01

42

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 ...

43

Gelation via Ion Exchange in Discotic Suspensions  

NASA Astrophysics Data System (ADS)

The phase behavior of charged disk suspensions displays a strong dependence on ionic strengths, as the interplay between excluded volume and electrostatic interactions determines the formation of glasses, gels, and liquid crystal states. The various ions in natural soil or brine, however, could present additional effects, especially considering that most platelet structures bear a momentous ion-exchange capacity. Here we observed how ion exchange modulates and controls the interaction between individual disks and leads to unconventional phase transitions from isotropic gel to nematic gel and finally to nematic liquid crystals.

Chang, Ya-Wen; Mejia, Andres F.; Cheng, Zhengdong; Di, Xiaojun; McKenna, Gregory B.

2012-06-01

44

Ion thruster charge-exchange plasma flow  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

45

Graphene/Ionic Liquid Composite Films and Ion Exchange  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

46

Graphene/Ionic Liquid Composite Films and Ion Exchange  

PubMed Central

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

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

2014-01-01

47

REMOVING RADIUM-226 ION EXCHANGE RESINS  

E-print Network

1 1 REMOVING RADIUM-226 FROM ION EXCHANGE RESINS USED IN DRINKING WATER TREATMENT James McMahon Dr) SEPTEMBER 22, 2007 2 Presentation Outline · Radionuclide/Radium-226 Regulations · Radium-226 Treatment for Radionuclides · 1962 US Public Health Services DWS ­ 3 pCi/L Radium 226 · 1977 USEPA National Interim Prim. DWS

48

Thermal Analysis of LANL Ion Exchange Column  

SciTech Connect

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.

Laurinat, J.E.

1999-06-16

49

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

PubMed

The isotope effects of neodymium in Nd-glycolate ligand exchange system were studied by using ion exchange chromatography. The separation coefficients of neodymium isotopes, ?'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, ?'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

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

2013-03-01

50

Magnetic ion exchange: Is there potential for international development?   

E-print Network

Magnetic ion exchange (MIEX®) is an ion exchange resin developed as an additive to existing water treatment plants where additional organic matter is to be removed. The smaller size, magnetic properties and simple ...

Neale, Peta A.; Schäfer, Andrea

2009-01-01

51

Ion transfer in ion-exchange and membrane materials  

NASA Astrophysics Data System (ADS)

Modern concepts of mass transport in solids are considered. Essential information on the structure of organic and inorganic ion-exchange materials and on defect formation processes is presented. The key methods of investigations of ion transfer are described. The results of studies on the transfer processes in membrane systems induced by various driving forces including the concentration, electric potential and electrochemical potential gradients are generalised.

Yaroslavtsev, Andrei B.; Nikonenko, Viktor V.; Zabolotsky, Viktor I.

2003-05-01

52

SPEEDUP{trademark} ion exchange column model  

SciTech Connect

A transient model to describe the process of loading a solute onto the granular fixed bed in an ion exchange (IX) column has been developed using the SpeedUp{trademark} software package. SpeedUp offers the advantage of smooth integration into other existing SpeedUp flowsheet models. The mathematical algorithm of a porous particle diffusion model was adopted to account for convection, axial dispersion, film mass transfer, and pore diffusion. The method of orthogonal collocation on finite elements was employed to solve the governing transport equations. The model allows the use of a non-linear Langmuir isotherm based on an effective binary ionic exchange process. The SpeedUp column model was tested by comparing to the analytical solutions of three transport problems from the ion exchange literature. In addition, a sample calculation of a train of three crystalline silicotitanate (CST) IX columns in series was made using both the SpeedUp model and Purdue University's VERSE-LC code. All test cases showed excellent agreement between the SpeedUp model results and the test data. The model can be readily used for SuperLig{trademark} ion exchange resins, once the experimental data are complete.

Hang, T.

2000-03-06

53

Ion-Exchange Celluloses and Their Use in Chromatography  

Microsoft Academic Search

CONTENTS I. Introduction 104 II. Preparation of ion-exchange celluloses 104 III. Properties of ion-exchange celluloses 105 IV. Technique of the application of ion-exchange celluloses 107 V. Uses of ion-exchange celluloses 110 Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text Return: Query Results Return items starting with number Query

E. G. Davidova; V. V. Rachinskii

1965-01-01

54

Porous solid ion exchange wafer for immobilizing biomolecules  

DOEpatents

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.

Arora, Michelle B. (Woodridge, IL); Hestekin, Jamie A. (Morton Grove, IL); Lin, YuPo J. (Naperville, IL); St. Martin, Edward J. (Libertyville, IL); Snyder, Seth W. (Lincolnwood, IL)

2007-12-11

55

Improved amphoteric ion exchanger and its manufacturing method  

Microsoft Academic Search

This invention relates to an amphoteric ion exchanger comprising a block copolymer composed of a polymer chain poly A(-) having a cation exchange group, poly B(+) polymer chain having an anion exchange group, and poly C polymer chain not having an ion exchange group, among which the constituent poly chain C is produced by adding hydrogen to a diene-group polymer.

T. Kodaka; H. Onuma

1985-01-01

56

Charge exchange lifetimes for ions in the magnetosphere  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

57

STUDY OF INDUSTRIAL ION EXCHANGE SEPARATION OF RARE EARTH ELEMENTS BY EDTA COPPER METHOD. 3. MANUFACTURE OF ION EXCHANGE EQUIPMENT  

Microsoft Academic Search

Ion exchange equipment was manufactured for trial. The equipment has ; five ion exchange towers, and the total capacity is 100 liters of strong acid ; type ion exchange resin. The equipment purifies 2.2 kg of rare earth into an ; oxide. In the case of refining of 2.2 kg of cerium oxide, 79% in purity, 1.37 kg ; of

K. Nishigori; T. Ishiyama; T. Kuroda

1961-01-01

58

Sorption of tellurium ion from aqueous solutions by anion-exchangers and amphoteric ion-exchangers  

SciTech Connect

Sorption of tellurium from solutions of telluric acid under dynamic and static conditions by anion-exchangers and amphoteric ion-exchangers containing various ionic groups was studied and the influence of the ion form, pH of the medium, presence of electrolytes, and the H/sub 6/TeO/sub 6/ concentration in the original solutions was determined. The mechanism of sorption of tellurium (VI) by anion-exchangers was deduced from sorption and IR-spectroscopic data. Differences in the behavior of tellurium and selenium were used for separating these elements in 0.05 N H/sub 2/SeO/sub 4/ + 0.05 N H/sub 6/TeO/sub 6/ solution of pH = 1.0 with the aid of EDE-10P anion-exchange resin.

Dreipa, E.F.; Pakholkov, V.S.; Luk'yanov, S.A.

1981-10-20

59

Ion exchange properties of humus acids  

NASA Astrophysics Data System (ADS)

Ion exchange equilibriums in a complex of brown humic acids (HAs) and related fulvic acids (FAs) with cations (H+, K+, Na+, Ca2+, Mg2+, Zn2+, Mn2+, Cu2+, Fe3+, and Al3+) have been studied, and the activity coefficients of the acid monoionic forms have been determined. The composition of the stoichiometric cell in the system of black and brown HAs and related FAs in a leached chernozem of the Ob' region has been calculated with consideration for the earlier studies of the ion exchange properties of black HAs and related FAs. It has been shown that hydrogen, calcium, magnesium, aluminum, and iron are the major components in the exchange complex of humus acids in the leached chernozem with the other cations being of subordinate importance. In spite of some differences between the analytical and calculated compositions of the humus acids, the results of the calculations can be considered satisfactory. They indicate that calculations are feasible for such complex objects as soils, and their accuracy will improve with the expansion of the experimental studies. The physicochemical simulation of the transformation of the humus acid composition under different acid-base conditions shows that the contents of most cations decrease under alkalization, and hydroxides or carbonates become the most stable forms of these cations. Under the acidification of solutions, the binding of alkaline and alkaline-earth elements by humus acids decreases and the adsorption of iron and aluminum by humus acids increases.

Shoba, V. N.; Chudnenko, K. V.

2014-08-01

60

Novel silica-based ion exchange resin  

SciTech Connect

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.

NONE

1997-11-01

61

Charge Exchange Processes for Highly Charged Ion -Atom, Molecule  

E-print Network

for Fusion Science H.A.Sakaue #12;Charge Exchange Processes Highly charged ions (HCI's) exist as an impurity ion in high temperature plasma. Charge exchange cross sections of HCI's are very large (~10-14cm2) Charge Exchange Processes of HCI's are very important for understanding the edge plasma behavior

Princeton Plasma Physics Laboratory

62

Ion exchange selectivity of a perfluorosulfonate ionomer  

E-print Network

and evaluation of my research. Gratitude is also extended to Robert B. Moore III for assistance with the preparation of columns for the HPLC, luminescence data and for verification of the many chromatographs that we ob- tained. TABLE OF CONTENTS... on Elution of Viologens 10 Effect of Organic Modifier on Elution of Pyridinium Zons 11 Elution of Pyridinium Zone with TMA-Cl as Eluent. 21 23 24 27 31 33 12 Ion Exchange Selectivity of Nafion Based HPLC Column 35 13 Elution of P-C from Column N...

Wilkerson, James Edward

1983-01-01

63

Ion exchange polymers and method for making  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

64

Ion exchange capacity of Nafion and Nafion composites  

Microsoft Academic Search

The ion exchange capacity of recast Nafion films and composites of Nafion and polystyrene microbeads is determined by titration. Composite formation enhances exchange capacity; exchange capacity increases with the surface area microbeads in the composite. For recast films, an equivalent weight of 996 {+-} 24 is found, whereas the lowest equivalent weight (highest exchange capacity) found for composite is 878

Ta-Yung Chen; Johna Leddy

2000-01-01

65

Radionuclide Leaching from Organic Ion Exchange Resin  

SciTech Connect

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.

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

1999-04-02

66

Mineral Separation in a CELSS by Ion-exchange Chromatography  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

67

Conducting polymers as ion-exchangers for water purification  

Microsoft Academic Search

The charging and discharging processes of conducting polymers, e.g. polypyrrole, are accompanied by the exchange of ions. This effect was used for the development of an electrochemically switchable ion-exchanger for water purification, especially for softening drinking water. The ion-exchange behaviour and capacity of electrochemically and chemically prepared polypyrrole (PPy) in dependence on the incorporated counterions are characterised using an electrochemical

C. Weidlich; K.-M. Mangold; K. Jüttner

2001-01-01

68

Effects of ionizing radiation on modern ion exchange materials  

SciTech Connect

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.

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

1993-10-01

69

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

SciTech Connect

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.

RAMSEY AA; THORSON MR

2010-12-28

70

Scintillating 99Tc Selective Ion Exchange Resins  

SciTech Connect

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.

Mitchell Greenhalgh; Richard D. Tillotson

2012-07-01

71

Pyrolysis of Spent Ion Exchange Resins - 12210  

SciTech Connect

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)

Braehler, Georg; Slametschka, Rainer [NUKEM Technologies GmbH (Germany)

2012-07-01

72

Waste treatment by selective mineral ion exchanger  

SciTech Connect

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)

Polito, Aurelie [Areva NC - BUA STMI, 1 route de la Noue - 91196 Gif sur Yvette, Cedex (France)

2007-07-01

73

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

SciTech Connect

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.

Ham, J.E.

1996-01-04

74

Modeling Multi-Metal Ion Exchange in Biosorption  

E-print Network

Modeling Multi-Metal Ion Exchange in Biosorption S I L K E S C H I E W E R A N D B O H U M I L V O heavy metals often through ion exchange. This biosorption can be used for purification of metal Biosorption, the passive non-metabolically mediated pro- cess of metal ion binding by living or dead biomass

Volesky, Bohumil

75

Electroplating rinse waste water treatment by ion exchange  

Microsoft Academic Search

Purification of copper containing waste waters from electroplating plants by means of different ion exchange units has been studied. The copper containing waste water with a range of copper concentration 55–60 mg\\/l, pH 3.3–3.5 has been treated of following schemes: (I) Weak base anion exchanger (OH-form) — weak acid cation exchanger (H-form) — strong base anion exchanger (OH-form); and (II)

I. Dobrevsky; M. Dimova-Todorova; T. Panayotova

1997-01-01

76

Controlled porosity monolithic material as permselective ion exchange membranes  

Microsoft Academic Search

Ion exchange membranes (IEMs) are used in a variety of analytical devices, including suppressors, eluent generators and other components used in ion chromatography. Such membranes are flexible and undergo substantial dimensional changes on hydration. Presently the push to miniaturization continues; a resurgent interest in open tubular ion chromatography requires microscale adaptation of these components. Incorporating IEMs in microscale devices is

Xiaojia Huang; Purnendu K. Dasgupta

2011-01-01

77

Gadolinium-hydrogen ion exchange of zirconium phosphate  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

78

Ion exchange capacity of Nafion and Nafion composites  

SciTech Connect

The ion exchange capacity of recast Nafion films and composites of Nafion and polystyrene microbeads is determined by titration. Composite formation enhances exchange capacity; exchange capacity increases with the surface area microbeads in the composite. For recast films, an equivalent weight of 996 {+-} 24 is found, whereas the lowest equivalent weight (highest exchange capacity) found for composite is 878 {+-} 8. This suggests that {approx_gt} 13% of the exchange sites within recast films are inaccessible for ion exchange; for 1,100 equivalent weight material, {approx_gt} 25% of the sulfonates are inaccessible. Equivalent weight results are consistent with an ordered interfacial domain between Nafion and the microbeads. A fractal model based on microbead radii, microbead fraction, and interfacial domain thickness provides a predictive model for designing composites with increased exchange capacity and cation transport.

Chen, T.Y.; Leddy, J.

2000-03-21

79

Ion-exchanged glass waveguide technology: a review  

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

80

Interpenetrating polymer network ion exchange membranes and method for preparing same  

DOEpatents

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.

Alexandratos, Spiro D. (Knoxville, TN); Danesi, Pier R. (Vienna, AT); Horwitz, E. Philip (Naperville, IL)

1989-01-01

81

Effects of silver and potassium ions on ion exchange in float glass  

Microsoft Academic Search

The variation of optical and mechanical properties in ion-exchanged glasses was investigated. Ion exchange was carried out in KNO3, NaNO3 melts and their mixed melts with AgNO3. The glasses used were soda-lime-silicate glasses produced by the float process. In order to analyse the effects of ion exchange, colour variation for optical properties, bending strength, surface microhardness and softening point for

D. I. Lee; Y. K. Lee; H. S. Lee

1992-01-01

82

Cesium Ion Exchange Loading Kinetics Testing with SRF Resin  

SciTech Connect

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.

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

2012-11-02

83

A mathematical relationship for the explanation of ion exchange for boron adsorption  

Microsoft Academic Search

The present study was undertaken to investigate a method for boron removal from wastewaters from boric acid and borax plants. The ion-exchange method is effective for the removal of boron from solution. The experimental results under different initial concentrations are first converted into dimensionless variables by taking ratios of volumes and concentrations and subsequently plotted on double logarithmic graph papers.

Sami ?ahin

2002-01-01

84

Tc-99 Ion Exchange Resin Testing  

SciTech Connect

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.

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

2010-08-01

85

Ion Exchange Separation of the Oxidation State of Vanadium.  

ERIC Educational Resources Information Center

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)

Cornelius, Richard

1980-01-01

86

FRACTIONATION OF COMPLEX MIXTURES USING AND ION-EXCHANGE METHODOLOGY  

EPA Science Inventory

Fractionation of particle emission extracts captured from complex combustion mixtures gas performed upon environmental samples using an ion-exchange technique. aptured emissions from hazardous waste, municipal and medical/pathological incinerators along with urban air imputed by ...

87

Optical waveguides fabricated by transition element ions exchange in some commercial and special optical glasses  

NASA Astrophysics Data System (ADS)

We present a fabrication and properties study of planar optical waveguides fabricated in a variety of commercially available as well as non-commercial special silicate-based optical glasses. The exchanged ions coming from external sources were Ag +, Cu +, Cu 2+ and Er 3+. The reduction of Ag + to Ag 0 from which the high optical losses of waveguides may originate was strongly enhanced when the glass contained reducing fining agents as As 2O 3 or Sb 2O 3. The Cu 2+ ion-exchange proceeded very quickly and resulted in the fabrication of waveguides with negligible birefringence. The samples containing exclusively Cu + exhibited very strong blue-green luminescence even in the cases of very low copper content in the exchanged surface layers. The purely thermal erbium ion-exchange was successful only in lithium containing glasses; when using the electric-field-assisted ion-exchange the erbium containing waveguides were fabricated also in several sodium-rich and sodium-potassium glasses. The shallow erbium-containing surface layers were deepened by the post-exchange annealing of the as-exchanged samples. The properties of the fabricated waveguides are discussed from the point of view of the composition of substrate glasses, taking into account the ratios of the bridging and non-bridging oxygen atoms in the glass matrices and the presence of fining agents.

Spirkova, Jarmila; Tresnakova-Nebolova, Pavlina; Mika, Martin

2004-03-01

88

Samarium Ion Exchanged Montmorillonite for High Temperature Cumene Cracking Reaction  

NASA Astrophysics Data System (ADS)

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.

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

2011-02-01

89

Topotaxial replacement of chlorapatite by hydroxyapatite during hydrothermal ion exchange  

Microsoft Academic Search

Exchange of Cl - by OH - in synthesized chlorapatite single crystals was investigated under hydro- thermal conditions. Hydrothermal treatments were performed at various temperatures from 200 to 500 °C, for intervals between 3 and 96 h in KOH or NaOH solutions. Ion exchange of Cl - in the chlorapatite crystals was completed at low temperature (500 °C) for a

K. YANAGISAWA; J. C. RENDON-ANGELES; N. ISHIZAWA; S. OISHI

1999-01-01

90

Detoxification of lignocellulose hydrolysates with ion-exchange resins  

Microsoft Academic Search

Lignocellulose hydrolysates contain fermentation inhibitors causing decreased ethanol production. The inhibitors include phenolic\\u000a compounds, furan aldehydes, and aliphatic acids. One of the most efficient methods for removing inhibiting compounds prior\\u000a to fermentation is treatment of the hydrolysate with ion-exchange resins. The performance and detoxification mechanism of\\u000a three different resins were examined: an anion exchanger, a cation exchanger, and a resin

Nils-Olof Nilvebrant; Anders Reimann; Simona Larsson; Leif J. Jönsson

2001-01-01

91

10 CFR Appendix E to Part 110 - Illustrative List of Chemical Exchange or Ion Exchange Enrichment Plant Equipment and Components...  

Code of Federal Regulations, 2012 CFR

...Part 110—Illustrative List of Chemical Exchange or Ion Exchange Enrichment...uranium causes small changes in chemical reaction equilibria that can be used as...successfully developed: liquid-liquid chemical exchange and solid-liquid...

2012-01-01

92

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

Microsoft Academic Search

A method is described 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. The ion exchanger is preferably a synthetic organic ion-exchange resin so

Dreyfuss

1976-01-01

93

Desalination of brackish waters using ion-exchange media  

SciTech Connect

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.

Pless, J.D.; Philips, M.L.F.; Voigt, J.A.; Moore, D.; Axness, M.; Krumhansl, J.L.; Nenoff, T.M. [Sandia National Labs., Albuquerque, NM (United States)

2006-06-21

94

The ion exchange phase in corrosion of nuclear waste glasses  

NASA Astrophysics Data System (ADS)

The diffusion-controlled ion exchange phase in the corrosion of nuclear waste borosilicate glasses has been examined using the Doremus' model accounting for interdiffusion and exchange of the cations in the glass with protons from the water. Ion exchange is the principal radionuclide release mechanism for conditions when glass network hydrolysis is suppressed, such as in silica-saturated solutions when ion exchange may persist over geological time scales. In dilute aqueous solutions ion exchange controls the initial cation release and can dominate for tens and many hundreds of years if temperatures are low at low and neutral pH. Ion exchange rates are shown to have inverse square root time dependences, an Arrhenius-controlled temperature relationship and a 10 -0.5pH dependence with the pH of the contacting water. Due to radioactive decay the radionuclide releases from nuclear waste glasses are limited to certain upper values, which can be calculated based on available experimental data.

Ojovan, Michael I.; Pankov, Alexey; Lee, William E.

2006-11-01

95

Electrical and magnetic properties of ion-exchangeable layered ruthenates  

SciTech Connect

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.

Sugimoto, Wataru [Faculty of Textile Science and Technology, Department of Fine Materials Engineering, Shinshu University, 3-15-1 Tokida, Ueda 386-8567 (Japan)]. E-mail: wsugi@shinshu-u.ac.jp; Omoto, Masashi [Faculty of Textile Science and Technology, Department of Fine Materials Engineering, Shinshu University, 3-15-1 Tokida, Ueda 386-8567 (Japan); Yokoshima, Katsunori [Faculty of Textile Science and Technology, Department of Fine Materials Engineering, Shinshu University, 3-15-1 Tokida, Ueda 386-8567 (Japan); Murakami, Yasushi [Faculty of Textile Science and Technology, Department of Fine Materials Engineering, Shinshu University, 3-15-1 Tokida, Ueda 386-8567 (Japan); Takasu, Yoshio [Faculty of Textile Science and Technology, Department of Fine Materials Engineering, Shinshu University, 3-15-1 Tokida, Ueda 386-8567 (Japan)

2004-12-01

96

Observations of O2:CO2 exchange ratios during ecosystem gas W. A. Brand, M. Heimann, and J. Lloyd2  

E-print Network

Observations of O2:CO2 exchange ratios during ecosystem gas exchange U. Seibt,1 W. A. Brand, M. Wingate (2004), Observations of O2:CO2 exchange ratios during ecosystem gas exchange, Global Biogeochem September 2004; accepted 21 September 2004; published 2 December 2004. [1] We determined O2:CO2 exchange

97

Silicon Removal from Waste Simulants via Ion Exchange  

SciTech Connect

examine a number of silica removal technologies to assist the processing of DWPF recycle water. Ion exchange is used commercially to remove soluble silicate ions and colloidal silica from various process waters. Three candidate ion exchange resins were selected after a literature search showed a potential applicability for DWPF Recycle. The results of these scouting tests showed the resins to be chemically stable in the alkaline environment of DWPF recycle. However, the resins were not effective at removing silicon. Additionally, results of silica analyses showed the silicon solubility in these feed solutions for ion exchange were still high after further acidification with respect to the goal of silicon removal. This suggests very strongly that pH adjustment (from 14 to 9), as a silicon removal technology is not viable.

Wilmarth, W.R.

2002-09-23

98

ION EXCHANGE PERFORMANCE OF TITANOSILICATES, GERMANATES AND CARBON NANOTUBES  

SciTech Connect

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.

Alsobrook, A.; Hobbs, D.

2013-04-24

99

Properties of a Novel Ion-Exchange Film  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

100

Coccolith B/Ca ratios using SIMS ion probe analysis  

NASA Astrophysics Data System (ADS)

B/Ca ratios are proposed as a paleo-carbonate ion or paleo-pH proxy due to the preferential incorporation of borate ion into the calcite lattice, relative to boric acid which is the dominant species of B at lower pH. The relative importance of cellular regulation vs external pH on the carbonate B/Ca remains to be characterized for most organisms. Here we describe initial results of B/Ca analyses of coccoliths produced in laboratory culture under variable carbonate ion concentrations. Due to the impossibility of physically separating the micron-sized coccoliths from non-coccolith sediment material in quantities large enough for TIMS or ICP-MS analysis of B/Ca, eventual analysis of coccolith B/Ca from the fossil record will need to be conducted on individually picked coccoliths on the ion probe as is currently done for other trace element (eg. Sr/Ca) ratios. Hence, we employ the CAMECA IMS 1280 ion probe at the Northeast National Ion Microprobe Facility at Woods Hole Oceanographic Institution to measure B/Ca in coccoliths from cultures. We evaluated cleaning methods using a synthetic cleaning target (crushed marble) contaminated with noncalcifying algae. Cleaning is crucial for obtaining accurate B/Ca ratios and precluding sample charging. B/Ca ratios of different genera of modern coccoliths range from 5 to 25 umol/mol, 3 to 10fold lower than planktic foraminifera or abiogenic calcite precipitated in seawater in the same pH range. These low ratios suggest much more restricted uptake of B into the algae cell in the vesicle calcification used by coccolithophores, compared with the seawater vacuole calcification typical of foraminifera. Different coccolith species grown at the same pH exhibit different B/Ca ratios. One species, Coccolithus pelagicus, cultured at a range of pH conditions from 7.7 to 8.4, exhibits no significant change in B/Ca ratios across the range of pH. One explanation is pH homeostasis at the calcification site. In possible support of pH homeostasis, the degree of calcification of this species was insensitive to variable CO2 and pH conditions in published experiments. We will also present results from strains of Emiliania huxleyi grown at different pH, for which more acidic pH resulted in depressed calcification.

Stoll, H.; Shimizu, N.; Langer, G.

2009-04-01

101

MINOR ACTINIDE SEPARATIONS USING ION EXCHANGERS OR IONIC LIQUIDS  

SciTech Connect

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.

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

2011-09-20

102

Collisional probe theory with charge exchange ions  

Microsoft Academic Search

The collisionless orbit-motion-limit (OML) theory is usually used to interpret Langmuir probe data. However, the ion current to a negatively biased probe is significantly increased by the effect of collisions, even for plasmas with a mean free path of 10^3 Debye lengths. For shorter mean free path the collisional ion current is dominant. We present a comprehensive theory for cylindrical

Zoltan Sternovsky

2002-01-01

103

Ion exchange polymers for anion separations  

DOEpatents

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.

Jarvinen, Gordon D. (Los Alamos, NM); Marsh, S. Fredric (Los Alamos, NM); Bartsch, Richard A. (Lubbock, TX)

1997-01-01

104

Separation Report No. 100 Ion Exchange  

E-print Network

cross-linked to the porous material surface. This article describes the basic properties, applications Features of TSK-GEL BioAssist series Item BioAssist Q BioAssist S Base material Porous acrylate-type gel-exchange. Figure 1 shows the pore characteristics of TSK-GEL BioAssist series. The unfunctionalized base material

Lebendiker, Mario

105

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...

106

Ion exchange polymers for anion separations  

DOEpatents

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.

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

1997-09-23

107

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

NASA Technical Reports Server (NTRS)

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.

Smith, J. K.

1975-01-01

108

Ion exchange synthesis of III-V nanocrystals.  

PubMed

III-V nanocrystals displaying high crystallinity and low size dispersity are difficult to access by direct synthesis from molecular precursors. Here, we demonstrate that cation exchange of cadmium pnictide nanocrystals with group 13 ions yields monodisperse, crystalline III-V nanocrystals, including GaAs, InAs, GaP, and InP. This report highlights the versatility of cation exchange for accessing nanocrystals with covalent lattices. PMID:23190283

Beberwyck, Brandon J; Alivisatos, A Paul

2012-12-12

109

The many faces of ion-exchange resins  

SciTech Connect

Ion-exchange resins have been used commercially for over 60 years. Softening and demineralization of water for boiler feed and process use were then, and continue to be, the most familiar and widespread applications of ion-exchange resins throughout the chemical process industries (CPI). Several types of membrane-based technologies, such as electrodialysis, reverse osmosis and, more recently, electrodeionization are recognized as alternative methods for water treatment. Yet, modern versions of ion-exchange resins remain a major player in water treatment. In addition, these versatile materials can be found performing a wide range of tasks in both aqueous and nonaqueous environments. Some of these diverse applications include: acid or base catalysis; manufacture of high-purity solvents and reagent chemicals; separation of by-products of fermentation processes; deacidification of organic solvents; high-purity water production for semiconductor manufacture; recovery of valuable waste from dilute process effluents; controlled release of pharmaceutical products; and chromatography, both on the analytical and the industrial scale. The key to understanding the potential of ion-exchange resins is to look beyond their exchange and adsorptive characteristics, and to see their fundamental nature. In other words, it`s necessary to first consider them as spherical, particulate reactive polymers that perform chemical reactions.

McNutty, J.T. [Rohm and Haas Co., Philadelphia, PA (United States)

1997-06-01

110

Polyamines and Pectins (I. Ion Exchange and Selectivity).  

PubMed Central

The ion-binding and -exchange properties of putrescine, spermidine, and spermine on purified walls of carrot (Daucus carota L.) cell suspensions were investigated by producing ion-exchange isotherms and comparing them with the behavior of Na+, Mg2+, and Ca2+. The cation exchange capacity of the carrot cell walls was 0.8 equivalent kg-1 dry matter, and the ionic selectivity sequence of the walls for polyamines followed the sequence spermine4+ > spermidine3+ [almost equal to] Ca2+ > putrescine2+. The polyamines were subjected to only electroselectivity and probably did not induce any favorable supramolecular conformation of pectin like the one induced by Ca2+. Triangular ion exchanges were also performed with three diamines: ethanediamine, butanediamine, and octanediamine. The shorter the diamine, the higher the total adsorption and selectivity of the exchange. The lower selectivity of the cell wall for putrescine was partly attributed to its inability to access and displace Ca2+ from higher affinity sites within dimerized pectic sequences. The polyamine adsorption and exchange on pectic sequences could result in pectic signal modulation in pathogenesis and in differentiation. PMID:12223613

Messiaen, J.; Cambier, P.; Van Cutsem, P.

1997-01-01

111

Rupture loop annex ion exchange RLAIX vault deactivation  

SciTech Connect

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.

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

1996-08-01

112

Selective ion-exchangers containing phosphorus in their functional groups  

Microsoft Academic Search

A series of selective ion-exchangers was synthetized, containing phosphinic or phosphonic acid functional groups. The selective\\u000a sorption of Sc3+, Fe3+, Ga3+, In3+, Al3+, La3+, Pb2+, Co2+ and Ca2+ ions in 0.1–4.0M HNO3 medium was investigated using a batch experiment technique. The selectivity of these exchangers generally decreased in the\\u000a order: Sc>Fe>In>Ga>Al>La>Pb>Cu>Co>Ca. The observed large differences in selectivity resulted in effective

M. Marhol; H. Beranová; K. L. Cheng

1974-01-01

113

Ion-exchanged Tm3+:glass channel waveguide laser.  

PubMed

Continuous wave laser action around 1.9 ?m has been demonstrated in a Tm(3+)-doped germanate glass channel waveguide laser fabricated by ion-exchange. Laser action was observed with an absorbed power threshold of only 44 mW and a slope efficiency of up to 6.8% was achieved. Propagation loss at the lasing wavelength was measured to be 0.3 dB/cm. We believe this to be the first ion-exchanged Tm(3+)-doped glass waveguide laser. PMID:23546272

Choudhary, Amol; Kannan, Pradeesh; Mackenzie, Jacob I; Feng, Xian; Shepherd, David P

2013-04-01

114

Catalysis using hydrous metal oxide ion exchangers  

DOEpatents

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.

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

1983-07-21

115

An Empirical Formula from Ion Exchange Chromatography and Colorimetry  

NASA Astrophysics Data System (ADS)

Experimental determination of the empirical formula for sodium salicylate, Nax(C7H5O3)y, using colorimetry and cation exchange. A Beer's Law plot is prepared for salicylate using 0.0050 M salicylic acid solution. Colorimetric analysis is performed on the salicylate ion in the form of an aqueous ferric complex, which is intensely violet-red, using a simple, inexpensive colorimeter constructed from readily available electronic parts and PVC pipe. Determination of sodium content is conducted using cation exchange, using simple re-usable exchange columns, followed by titration with OH-. The procedure is involved, yet has been conducted by high school chemistry students as a lab final.

Johnson, Steven D.

1996-12-01

116

Insoluble polyelectrolyte and ion-exchange hollow fiber impregnated therewith  

NASA Technical Reports Server (NTRS)

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.

Rembaum, A. (inventor)

1977-01-01

117

Plasma ion temperature measurements via charge-exchange recombination radiation  

SciTech Connect

Spatially and temporally resolved plasma ion temperatures can be determined by measuring the Doppler-broadened line profiles of transitions excited by charge-exchange recombination reactions between fast hydrogen atoms and fully ionized low-Z ions. Plasma rotation velocity profiles can also be obtained. A sample result from the PDX tokamak using He/sup +/ radiation is presented, and expected line intensities for model cases for PDX and TFTR are calculated.

Fonck, R.J.; Goldston, R.J.; Kaita, R.; Post, D.E.

1982-11-01

118

Modeling Uranium-Proton Ion Exchange in Biosorption  

E-print Network

Modeling Uranium-Proton Ion Exchange in Biosorption J I N B A I Y A N G A N D B O H U M I L V O L E, Quebec, Canada H3A 2B2 Biosorption of uranium metal ions by a nonliving protonated Sargassum fluitans seaweed biomass was used to remove the heavy metal uranium from the aqueous solution. Uranium biosorption

Volesky, Bohumil

119

Extraction and ion-exchange behavior of mendelevium (II)  

Microsoft Academic Search

Medelevium-256 was obtained via multinucleon transfer reactions upon irradiation of ²⁴⁹Bk by ²²Ne 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.

L. I. Guseva; G. S. Tikhomirova; G. V. Buklanov; Z. Z. Pkhar; I. A. Lebedev; N. V. Katargin; B. F. Myasoedov

1988-01-01

120

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

Microsoft Academic Search

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

Dreyfuss; Robert M

1976-01-01

121

25th anniversary article: Ion exchange in colloidal nanocrystals.  

PubMed

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 outlook for the field in terms of the emerging applications and the ion exchange derived materials that will enable them. PMID:24108549

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

2013-12-23

122

Fission product ion exchange between zeolite and a molten salt  

NASA Astrophysics Data System (ADS)

The electrometallurgical treatment of spent nuclear fuel (SNF) has been developed at Argonne National Laboratory (ANL) and has been demonstrated through processing the sodium-bonded SNF from the Experimental Breeder Reactor-II in Idaho. In this process, components of the SNF, including U and species more chemically active than U, are oxidized into a bath of lithium-potassium chloride (LiCl-KCl) eutectic molten salt. Uranium is removed from the salt solution by electrochemical reduction. The noble metals and inactive fission products from the SNF remain as solids and are melted into a metal waste form after removal from the molten salt bath. The remaining salt solution contains most of the fission products and transuranic elements from the SNF. One technique that has been identified for removing these fission products and extending the usable life of the molten salt is ion exchange with zeolite A. A model has been developed and tested for its ability to describe the ion exchange of fission product species between zeolite A and a molten salt bath used for pyroprocessing of spent nuclear fuel. The model assumes (1) a system at equilibrium, (2) immobilization of species from the process salt solution via both ion exchange and occlusion in the zeolite cage structure, and (3) chemical independence of the process salt species. The first assumption simplifies the description of this physical system by eliminating the complications of including time-dependent variables. An equilibrium state between species concentrations in the two exchange phases is a common basis for ion exchange models found in the literature. Assumption two is non-simplifying with respect to the mathematical expression of the model. Two Langmuir-like fractional terms (one for each mode of immobilization) compose each equation describing each salt species. The third assumption offers great simplification over more traditional ion exchange modeling, in which interaction of solvent species with each other is considered. (Abstract shortened by UMI.)

Gougar, Mary Lou D.

123

A new hybrid ion exchanger: effect of system parameters on the adsorption of vanadium (V).  

PubMed

The hybrid ion exchanger consisted of PONF-g-GMA anion fibrous exchanger and IRA-96 bead-type anion exchanger was developed by combining different types of layers with hot-melt adhesive. Its ion exchange capacity and the pressure drop with flow rate of water were measured and the adsorption of vanadium (V) ions on the hybrid ion exchanger was evaluated with various process parameters such as pH, initial concentration, and temperature. It was observed that the adsorption kinetics of vanadium (V) ions on the hybrid ion exchanger could be analyzed with pseudo-second-order model. PMID:19118945

Yeom, Bong-Yeol; Lee, Chang-Soo; Hwang, Taek-Sung

2009-07-15

124

Swelling and dehydration characteristics of transition metal ion-exchanged taeniolites  

Microsoft Academic Search

The swelling and dehydration characteristics of Mn2+, Ni2+, Cu2+ and Zn2+ ion-substituted taeniolites with the exchange ratios of 85% and 78% have been investigated by high-temperature X-ray diffractometry, thermogravimetry-differential thermal analysis and calorimetry. The transition metal forms are the swelling states with two water-molecule layers at room temperature and a relative humidity of 70%, and their dehydration processes to the

Michihiro Miyake; Hiroyuki Yamaguchi; Takashi Suzuki

1990-01-01

125

Thermal Analysis for Ion-Exchange Column System  

SciTech Connect

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.

Lee, Si Y.; King, William D.

2012-12-20

126

Copper Removal from A-01 Outfall by Ion Exchange  

SciTech Connect

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.

Oji, L.N.

1999-02-17

127

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...

128

EVALUATING ION EXCHANGE FOR REMOVING RADIUM FROM GROUNDWATER  

EPA Science Inventory

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

129

ION-EXCHANGE PROCESSES AND MECHANISMS IN GLASSES  

EPA Science Inventory

Recent performance assessment calculations of a disposal system at Hanford, Washington for low activity waste glass show that a Na ion-exchange reaction can effectively increase the radionuclide release rate by over a factor of 1000 and so is a major factor that currently limits ...

130

Cesium Ion Exchange Using Tank 241-AN-104 Supernate  

SciTech Connect

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.

Adu-Wusu, K.

2003-12-22

131

Method and solvent composition for regenerating an ion exchange resin  

DOEpatents

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.

Even, William R. (Livermore, CA); Irvin, David J. (Livermore, CA); Irvin, Jennifer A. (Livermore, CA); Tarver, Edward E. (Livermore, CA); Brown, Gilbert M. (Knoxville, TN); Wang, James C. F. (Livermore, CA)

2002-01-01

132

ATPases, ion exchangers and human sperm motility.  

PubMed

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 ? subunit of the NKA in the sperm plasma membranes (?1 and ?4), being ?4 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. PMID:25820902

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

2015-05-01

133

The functional ontogeny of the teleost gill: which comes first, gas or ion exchange?  

PubMed

For most of the last century, the need to obtain sufficient oxygen to meet the respiratory requirements of the tissues was viewed as the primary selective pressure driving gill development in teleost fish. Recently, however, it has been suggested that ionoregulatory pressures may actually be more important. This manuscript reviews the theoretical and empirical evidence dealing with the functional ontogeny of the gill in the context of the oxygen and ionoregulatory hypotheses. Gas and ion exchange are subject to similar geometric constraints in developing fish. Both initially are exclusively cutaneous but shift to the gill with tissue growth because of declining surface-to-volume ratios. Based on the appearance of mitochondria-rich cells (MRCs), ionoregulatory activity shifts to the gill in advance of gas exchange. In every species examined to date, MRCs appear on the developing gill in advance of secondary lamellae, the definitive gas exchange structure of the adult gill. Biochemical and histochemical studies indicate that these early branchial MRCs are actively involved in ion exchange. In some cases, the specific activity is many times greater than in the adult gill. In contrast, O2 microelectrode and hemoglobin ablation experiments suggest that the early gill contributes little O2 to the general systemic circulation. Any oxygen taken up appears to be consumed locally. Functional ablation experiments with zebrafish indicated that the larval gill became essential for ion balance well before it was needed for O2 uptake. Similar experiments with rainbow trout, however, found that the gill became essential in terms of gas and ion exchange at about the same time. On balance, the evidence appears to favour the ionoregulatory hypothesis but the oxygen hypothesis cannot be absolutely rejected without more information. Some of the major deficiencies in our knowledge regarding the transition from cutaneous to branchial gas and ion exchange are highlighted and potential implications of the ionoregulatory hypothesis are discussed. PMID:17451987

Rombough, Peter

2007-12-01

134

Ion exchange as a tertiary treatment  

E-print Network

considerable interest has been di- rected toward the field of advanced waste water treatment, commonly termed tertiary treatment. One advanced waste treatment process that has shown great promise is ion ex? change. Reported herein are the results... will usually obtain and use fresh water due to the high quality requi. red for domestic use. The city' s waste water is then treated to remove the contaminants and the water is then reused by industry. The amount of treatment and the quality of the treated...

Westervelt, Ronald David

1968-01-01

135

Removal of bromide ions from an aqueous solution by Donnan dialysis with anion-exchange membranes  

Microsoft Academic Search

The potential of Donnan dialysis to remove the bromide ions and associated ions (nitrates and bicarbonates) from a model solution was examined, using three anion-exchange membranes (AMEs) differing in their ion-exchange capacity and water content: Selemion AMV, Neosepta AFN and Neosepta ACS. Selemion AMV provided the most advantageous exchange of bromide ions for chloride ions and effectively limited co-ion transport,

Sylwia ?akomska; Jacek Wi?niewski

2012-01-01

136

Separation of americium from curium by oxidation and ion exchange.  

PubMed

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. PMID:22827724

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

2012-08-21

137

Refractive Index Profiles of Copper Ion Exchange Glass Planar Waveguides  

NASA Astrophysics Data System (ADS)

Glass planar optical waveguides are fabricated by the copper ion-exchange technique. The refractive index (RI) profiles of waveguides are reconstructed by the inverse Wentzel-Kramers-Brillouin (IWKB) method. Cu+ and Cu2+ ion concentrations are calculated by solving the diffusion equation, and the mechanism of RI changes is analyzed. The model between the RI and ion concentrations is proposed by taking both Cu+ and Cu2+ into account, according to polarizability changes among Cu+, Cu2+ and Na+. The results show that the contribution of Cu2+ is not negligible, and the reason for the RI change is of Cu+ and Cu2+. With the exchange time increasing, the redox process between Cu+ and Cu2+ will play an important role on RI profiles.

Xia, Hong-Yun; Teng, Chuan-Xin; Zhao, Xiao-Wei; Zheng, Jie

2012-08-01

138

Heavy baryon/meson ratios in relativistic heavy ion collisions  

E-print Network

Heavy baryon/meson ratios $\\Lambda_c/D^0$ and $\\Lambda_b/\\bar{B}^0$ in relativistic heavy ion collisions are studied in the quark coalescence model. For heavy baryons, we include production from coalescence of heavy quarks with free light quarks as well as with bounded light diquarks that might exist in the strongly coupled quark-gluon plasma produced in these collisions. Including the contribution from decays of heavy hadron resonances and also that due to fragmentation of heavy quarks that are left in the system after coalescence, the resulting $\\Lambda_c/D^0$ and $\\Lambda_b/\\bar{B}^0$ ratios in midrapidity ($|y|\\le 0.5$) from central Au+Au collisions at $\\sqrt{s_{NN}}=200$ GeV are about a factor of five and ten, respectively, larger than those given by the thermal model, and about a factor of ten and twelve, respectively, larger than corresponding ratios in the PYTHIA model for $pp$ collisions. These ratios are reduced by a factor of about 1.6 if there are no diquarks in the quark-gluon plasma. The transverse momentum dependence of the heavy baryon/meson ratios is found to be sensitive to the heavy quark mass, with the $\\Lambda_b/\\bar{B}^0$ ratio being much flatter than the $\\Lambda_c/D^0$ ratio. The latter peaks at the transverse momentum $p_T^{} \\simeq 0.8$ GeV but the peak shifts to $p_T^{} \\simeq 2$ GeV in the absence of diquarks.

Yongseok Oh; Che Ming Ko; Su Houng Lee; Shigehiro Yasui

2009-01-12

139

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

140

Grafted megaporous materials as ion-exchangers for bioproduct adsorption.  

PubMed

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. PMID:23401432

Bibi, Noor Shad; Fernández-Lahore, Marcelo

2013-01-01

141

Charge-exchange plasma generated by an ion thruster  

NASA Technical Reports Server (NTRS)

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.

Kaufman, H. R.

1975-01-01

142

Syntesis of lanthanum zirconate hydrosols by the ion exchange method  

Microsoft Academic Search

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

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

2011-01-01

143

Syntesis of lanthanum zirconate hydrosols by the ion exchange method  

NASA Astrophysics Data System (ADS)

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.

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

2011-04-01

144

Ion exchange of zeolite membranes by a vacuum `flow-through' Seok-Jhin Kim a  

E-print Network

Ion exchange of zeolite membranes by a vacuum `flow-through' technique Seok-Jhin Kim October 2014 Keywords: Ion exchange Zeolite membrane Flow-through technique Separation Catalysis a b s t r a c t Ion exchange of nanoporous (e.g., zeolite) membranes is of increasing importance

Nair, Sankar

145

Composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix  

Microsoft Academic Search

Methods of preparation of granules of inorganic ion exchangers as well as methods for improvement of granular strength of these materials are reviewed. The resulting ion exchangers are classified in three groups—intrinsic, supported and composite ion exchangers. Their properties are compared and possibilities of their technological application are evaluated. A new method of preparation of inorganic-organic composite sorbents of inorganic

F. Šebesta

1997-01-01

146

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...

147

Radon (222Rn) in ground water of fractured rocks: A diffusion/ion exchange model  

USGS Publications Warehouse

Ground waters from fractured igneous and high-grade sialic metamorphic rocks frequently have elevated activity of dissolved radon (222Rn). A chemically based model is proposed whereby radium (226Ra) from the decay of uranium (238U) diffuses through the primary porosity of the rock to the water-transmitting fracture where it is sorbed on weathering products. Sorption of 226Ra on the fracture surface maintains an activity gradient in the rock matrix, ensuring a continuous supply of 226Ra to fracture surfaces. As a result of the relatively long half-life of 226Ra (1601 years), significant activity can accumulate on fracture surfaces. The proximity of this sorbed 226Ra to the active ground water flow system allows its decay progeny 222Rn to enter directly into the water. Laboratory analyses of primary porosity and diffusion coefficients of the rock matrix, radon emanation, and ion exchange at fracture surfaces are consistent with the requirements of a diffusion/ion- exchange model. A dipole-brine injection/withdrawal experiment conducted between bedrock boreholes in the high-grade metamorphic and granite rocks at the Hubbard Brook Experimental Forest, Grafton County, New Hampshire, United States (42??56???N, 71??43???W) shows a large activity of 226Ra exchanged from fracture surfaces by a magnesium brine. The 226Ra activity removed by the exchange process is 34 times greater than that of 238U activity. These observations are consistent with the diffusion/ion-exchange model. Elutriate isotopic ratios of 223Ra/226Ra and 238U/226Ra are also consistent with the proposed chemically based diffusion/ion-exchange model.

Wood, W.W.; Kraemer, T.F.; Shapiro, A.

2004-01-01

148

Radon (222Rn) in ground water of fractured rocks: a diffusion/ion exchange model.  

PubMed

Ground waters from fractured igneous and high-grade sialic metamorphic rocks frequently have elevated activity of dissolved radon (222Rn). A chemically based model is proposed whereby radium (226Ra) from the decay of uranium (238U) diffuses through the primary porosity of the rock to the water-transmitting fracture where it is sorbed on weathering products. Sorption of 226Ra on the fracture surface maintains an activity gradient in the rock matrix, ensuring a continuous supply of 226Ra to fracture surfaces. As a result of the relatively long half-life of 226Ra (1601 years), significant activity can accumulate on fracture surfaces. The proximity of this sorbed 226Ra to the active ground water flow system allows its decay progeny 222Rn to enter directly into the water. Laboratory analyses of primary porosity and diffusion coefficients of the rock matrix, radon emanation, and ion exchange at fracture surfaces are consistent with the requirements of a diffusion/ion-exchange model. A dipole-brine injection/withdrawal experiment conducted between bedrock boreholes in the high-grade metamorphic and granite rocks at the Hubbard Brook Experimental Forest, Grafton County, New Hampshire, United States (42 degrees 56'N, 71 degrees 43'W) shows a large activity of 226Ra exchanged from fracture surfaces by a magnesium brine. The 226Ra activity removed by the exchange process is 34 times greater than that of 238U activity. These observations are consistent with the diffusion/ion-exchange model. Elutriate isotopic ratios of 223Ra/226Ra and 238U/226Ra are also consistent with the proposed chemically based diffusion/ion-exchange model. PMID:15318778

Wood, Warren W; Kraemer, Thomas F; Shapiro, Allen

2004-01-01

149

Detoxification of lignocellulose hydrolysates with ion-exchange resins.  

PubMed

Lignocellulose hydrolysates contain fermentation inhibitors causing decreased ethanol production. The inhibitors include phenolic compounds, furan aldehydes, and aliphatic acids. One of the most efficient methods for removing inhibiting compounds prior to fermentation is treatment of the hydrolysate with ion-exchange resins. The performance and detoxification mechanism of three different resins were examined: an anion exchanger, a cation exchanger, and a resin without charged groups (XAD-8). A dilute acid hydrolysate of spruce was treated with the resins at pH 5.5 and 10.0 prior to ethanolic fermentation with Saccharomyces cerevisiae. In addition to the experiments with hydrolysate, the effect of the resins on selected model compounds, three phenolics (vanillin, guaiacol, and coniferyl aldehyde) and two furan aldehydes (furfural and hydroxymethyl furfural), was determined. The cation exchanger increased ethanol production, but to a lesser extent than XAD-8, which in turn was less effective than the anion exchanger. Treatment at pH 10.0 was more effective than at pH 5.5. At pH 10.0, the anion exchanger efficiently removed both anionic and uncharged inhibitors, the latter by hydrophobic interactions. The importance of hydrophobic interactions was further indicated by a substantial decrease in the concentration of model compounds, such as guaiacol and furfural, after treatment with XAD-8. PMID:11963864

Nilvebrant, N O; Reimann, A; Larsson, S; Jönsson, L J

2001-01-01

150

Radiation degradation in EPICOR-2 ion exchange resins  

SciTech Connect

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.

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

1990-09-01

151

Water Exchange Rates and Molecular Mechanism around Aqueous Halide Ions  

SciTech Connect

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.

Annapureddy, Harsha V.; Dang, Liem X.

2014-07-17

152

Ytterbium-doped glass waveguide laser fabricated by ion exchange  

Microsoft Academic Search

A ytterbium-doped, glass, channel waveguide laser, fabricated by ion exchange, is reported. The 2.2 cm long device, using broad-band 4% output couplers, lased in the vicinity from 1020 to 1030 nm when pumped by a Ti:sapphire laser operating at 910 nm. A lasing threshold of 50 mW (launched pump) and a slope efficiency of 5% were measured. Device parameters, including

Catalin Florea; Kim A. Winick

1999-01-01

153

Mercury removal from water by ion exchange resins adsorption  

Microsoft Academic Search

In this paper a detailed experimental and theoretical analysis of the adsorption process of mercury by ion exchange resins is presented. Experiments have been performed to study adsorption efficiency, the effect of pH on the uptake of mercury and the adsorption kinetics. The experimental apparatus was a batch mechanically stirred reactor (volume 1.5 dm3), under almost isothermal conditions (±0.1°C). The

S. Chiarle; M. Ratto; M. Rovatti

2000-01-01

154

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

SciTech Connect

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.

Duncan, J.B.

1998-08-25

155

CHARACTERIZATION OF CYCLED SPHERICAL RESORCINOL-FORMALDEHYDE ION EXCHANGE RESIN  

Microsoft Academic Search

This report presents characterization data for two spherical resorcinol-formaldehyde (sRF) resin beds that had processed cesium in non-radioactive and radioactive cycles. All column cycle operations for the resin beds including loading, displacements, elution, regeneration, breakthroughs, and solution analyses are reported in Nash and Duignan, 2009a. That report covered four ion exchange (IX) campaigns using the two 11 mL beds in

C. Nash; M. Duignan

2010-01-01

156

Cyanide recycling using strong-base ion-exchange resins  

NASA Astrophysics Data System (ADS)

Among the techniques available to recover cyanide and metal cyanocomplexes from diluted streams, ion-exchange resins seem attractive because of the possibility of treating either pulps or clear solutions with this process. This article discusses the results of adsorption and elution of metal cyanocomplexes obtained with industrial effluents and selected data from the literature. The behavior of iron and copper cyanocomplexes during elution is emphasized.

Leão, Versiane Albis; Ciminelli, Virgínia S. T.; Costa, Renato De Souza

1998-10-01

157

Isolation and ion exchanging behaviour of mendelevium\\/II  

Microsoft Academic Search

Mendelevium-256 was obtained by irradiating of Bk-249 with Ne-22 ions in the external beam of U-300 cyclotron. An efficient ionexchanging method of medelevium isolation and separation from nuclear reaction products have been developed in which a column with cation exchanger and zinc amalgam and 1M HCl solutions as eluents were used. Under these conditions mendelevium has been shown to be

L. I. Guseva; G. S. Tikhomirova; G. V. Buklanov; Zen Zin Phar; I. A. Lebedev; N. V. Katargin; B. F. Myasoedov

1987-01-01

158

Metal ion exchange by natural and modified zeolites  

Microsoft Academic Search

The lead and cadmium removal from wastewaters by natural and pretreatment zeolites was examined by using a batch-type method. The results demonstrated that the natural zeolites contained a complement of exchangeable Na, K and Ca ions but exposing them to 2 M NaCl solution at 22 and 70°C, respectively, converted them to a near homoionic state in Na-form. Lead and

L. ?urkovi?; Š. Cerjan-Stefanovi?; T. Filipan

1997-01-01

159

Exchange bias in polycrystalline magnetite films made by ion-beam assisted deposition  

SciTech Connect

Iron oxide films were deposited onto Si substrates using ion-beam-assisted deposition. The films were ~300 nm thick polycrystalline magnetite with an average crystallite size of ~6 nm. Additionally, incorporation of significant fractions of argon in the films from ion bombardment is evident from chemical analysis, and Fe/O ratios are lower than expected from pure magnetite. However, Raman spectroscopy and x-ray diffraction both indicate that the films are single-phase magnetite. Since no direct evidence of a second phase could be found, exchange bias likely arises due to defects at grain boundaries, possibly amorphous, creating frustrated spins. Since these samples have such small grains, a large fraction of the material consists of grain boundaries, where spins are highly disordered and reverse independently with external field. The high energy deposition process results in an oxygen-rich, argon-containing magnetite film with low temperature exchange bias due to defects at the high concentration of grain boundaries.

Kaur, Maninder; Jiang, Weilin; Qiang, You; Burks, Edward; Liu, Kai; Namavar, Fereydoon; Mccloy, John S.

2014-11-03

160

Effects of ion-exchangeable cations on coal ash mineralogy  

SciTech Connect

The purpose of this study was to investigate the effect of ion-exchangeable cations on ash mineralogies of two coals having different sodium contents. In addition, ashes of the same coals from which the exchangeable cations were removed were compared with ashes of the non-exchanged coals to determine the effect of removing alkali cations on ash mineralogies. Two lignites from the Gascoyne Mine, North Dakota, were chosen for this study. Both samples were collected within the same coal seam but from different pits: the Gascoyne Red and Blue Pits. Based on pilot plant combustion experience, the Gascoyne Red Pit coal is characterized as a low-fouling lignite relatively low in sodium, while the Gascoyne Blue Pit coal is a moderate to high-fouling lignite relatively high in sodium. Ion-exchange data for these two coals has been previously reported. Results suggest that systems abundant in calcium and sodium cations form feldspathoids at lower temperatures than systems deficient in these cations by mechanisms previously described. At 1000/sup 0/C, both calcium and sodium were present in the form of gehlenite and nepheline, respectively. In no case did mutual substitution of calcium and sodium occur within the same aluminosilicate structure. Perhaps this behavior reflects a preference for specific cations to substitute within aluminosilicate structures having different coordination configurations. 6 references, 2 tables.

Falcone, S.K.; Hurley, J.P.; Schobert, H.H.

1984-11-01

161

Raman microspectroscopy investigation of Ag ion-exchanged glass layers.  

PubMed

The ion-exchange process is widely used to dope silicate glass layers with silver, aimed at controlling the Ag state in view of possible applications, ranging from light waveguide fabrication to nanostructured composite glass synthesis. The silver doped glass structure as well as its prescribed properties depend on both the preparation parameters and the subsequent treatments. Several structural aspects are still open with regard either to the modification of the glass incorporating the dopant, or to clustering phenomena silver undergoes as a function of its local concentration and state, which are in turn strongly dependent on the preparation route. Systematic characterizations of these systems are mandatory to address the role of the various synthesis parameters in giving rise to the observed features, thus pointing out the effective methodologies for the fabrication of silicate glass layers with the desired properties. In this work, the results of micro-Raman, optical absorption and photoluminescence characterizations are presented for soda-lime glass slides doped with silver by Ag(+)-Na+ exchange and subsequent thermal treatments in air. In particular, a cross-section profiling analysis by Raman micro-spectroscopy was performed on Ag ion-exchanged samples after treatment at some different temperatures. The experimental findings allow to elucidate the role of the treatment temperature in the clustering process related to the local Ag concentration inside the exchanged glass layer. PMID:23421246

Rahman, A; Giarola, M; Cattaruzza, E; Gonella, F; Mardegan, M; Trave, E; Quaranta, A; Mariotto, G

2012-11-01

162

The quantitative ion exchange separation of uranium from impurities  

SciTech Connect

Two methods were tested for the quantitative separation of uranium from elemental impurities using commercially available resins. The sorption and elution behavior of uranium and the separation of it from a variety of other elements was studied. The first method utilized an anion exchange resin while the second method employed an extraction resin. The first method, the anion exchange of uranium (VI) in an acid chloride medium, was optimized and statistically tested for quantitative recovery of uranium. This procedure involved adsorption of uranium onto Blo-Rad AG 1-X8 or MP-1 ion exchange resins in 8 M HCl, separation of uncompleted or weakly complexed matrix ions with an 8 M HCI wash, and subsequent elution of uranium with 1 M HCl. Matrix ions more strongly adsorbed than uranium were left on the resin. Uranium recoveries with this procedure averaged greater than 99.9% with a standard deviation of 0.1%. In the second method, recovery of uranium on the extraction resin did not meet the criteria of this study and further examination was terminated.

Narayanan, U.I.; Mason, P.B.; Zebrowski, J.P.; Rocca, M.; Frank, I.W.; Smith, M.M.; Johnson, K.D.; Orlowicz, G.J.; Dallmann, E.

1995-03-01

163

Thermal analysis for ion-exchange column system  

SciTech Connect

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)

Lee, S. Y.; King, W. D. [Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808 (United States)

2012-07-01

164

Characterization of ion-exchange membrane materials: properties vs structure.  

PubMed

This review focuses on the preparation, structure and applications of ion-exchange membranes formed from various materials and exhibiting various functions (electrodialytic, perfluorinated sulphocation-exchange and novel laboratory-tested membranes). A number of experimental techniques for measuring electrotransport properties as well as the general procedure for membrane testing are also described. The review emphasizes the relationships between membrane structures, physical and chemical properties and mechanisms of electrochemical processes that occur in charged membrane materials. The water content in membranes is considered to be a key factor in the ion and water transfer and in polarization processes in electromembrane systems. We suggest the theoretical approach, which makes it possible to model and characterize the electrochemical properties of heterogeneous membranes using several transport-structural parameters. These parameters are extracted from the experimental dependences of specific electroconductivity and diffusion permeability on concentration. The review covers the most significant experimental and theoretical research on ion-exchange membranes that have been carried out in the Membrane Materials Laboratory of the Kuban State University. These results have been discussed at the conferences "Membrane Electrochemistry", Krasnodar, Russia for many years and were published mainly in Russian scientific sources. PMID:18394577

Berezina, N P; Kononenko, N A; Dyomina, O A; Gnusin, N P

2008-06-22

165

Passive and Active Ion-Exchanged Glass Waveguides and Devices  

NASA Astrophysics Data System (ADS)

This thesis studies the fabrication and the characterization of passive and active ion-exchanged glass waveguides and devices that are mainly used for applications in integrated optics area. Potassium and silver double-ion-exchange process is developed to fabricate high performance passive glass waveguides and devices. Three different processes are investigated for the fabrication of rare-earth-doped glass waveguides on active and passive substrates. They are dilute silver ion exchange for rare-earth-doped silicate glass substrates, spin-coated rare-earth-doped phosphate overlays on passive glass waveguides and composite structures employing active cover glass on passive waveguides. The main rare-earth elements employed in the fabrication of active waveguides are neodymium and erbium. Grating assisted glass waveguides, symmetric Y -branches, a novel four-port nonsymmetric Mach-Zehnder interferometer and a new integrated optical ring resonator are developed. They are potentially important for active applications in connection with rare-earth-doped glass waveguides. Finally, a composite erbium-doped glass waveguide amplifier is demonstrated and more than 10 dB net gain has been achieved with a 4.7 mm long sample and less than 30 mW guided pump power in the waveguide.

Wang, Wei-Jian

166

Ion exchange extraction of heavy metals from wastewater sludges.  

PubMed

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. PMID:15027828

Al-Enezi, G; Hamoda, M F; Fawzi, N

2004-01-01

167

Elimination of ion losses in EGP-10-1 charge-exchange accelerator  

SciTech Connect

The ion-optical properties of the injector are studied to increase the ion transmission coefficient in the EGP-10-1 charge-exchange accelerator. Injector optimization provides almost complete ion transmission for all conductor voltages.

Friedrich, M.

1987-01-01

168

Ion-optical studies for improved ion transmission in multistage isotope-ratio mass spectrometers  

SciTech Connect

Theoretical and experimental ion-optical studies of multistage isotope-ratio mass spectrometers were conducted to determine what improvement in ion transmission efficiency might be attainable through design changes. The computer program GIOS (General Ion Optical Systems) was used to perform theoretical calculations of focusing properties and ion transmission efficiency. Actual transmission through multiple-sector instruments was determined from measurements of the ion beam vertical profile at the focus of each stage. For existing mass spectrometers with tandem magnets of normal geometry, our studies determined a feasible design change that significantly increases ion transmission through the analyzer. The use of a cylindrical einzel lens or an electrostatic quadrupole lens near the focal point between the magnets provides vertical focusing of the ion beam to achieve the improved transmission. We also established a new mass spectrometer design that give 100% transmission through tandem magnetic analyzers and through a third-stage electrostatic analyzer without the use of an intermediate focusing lens. Non-normal magnetic field boundaries provide ion beam focusing in the vertical plant to achieve this complete transmission. 19 refs., 27 figs., 3 tabs.

Stoffels, J.J. (Pacific Northwest Lab., Richland, WA (United States)); Laue, H.J. (Purdue Univ., Lafayette, IN (United States))

1991-10-01

169

Negative Joule Heating in Ion-Exchange Membranes  

E-print Network

In ion-exchange membrane processes, ions and water flow under the influence of gradients in hydrostatic pressure, ion chemical potential, and electrical potential (voltage), leading to solvent flow, ionic fluxes and ionic current. At the outer surfaces of the membranes, electrical double layers (EDLs) are formed (Donnan layers). When a current flows through the membrane, we argue that besides the positive Joule heating in the bulk of the membrane and in the electrolyte outside the membrane, there is also negative Joule heating in one of the EDLs. We define Joule heating as the inner product of the two vectors current and field strength. Also when fluid flows through a charged membrane, at one side of the membrane there is pressure-related cooling, due to the osmotic and hydrostatic pressure differences across the EDLs.

Biesheuvel, P M; Hamelers, H V M

2014-01-01

170

Negative Joule Heating in Ion-Exchange Membranes  

E-print Network

In ion-exchange membrane processes, ions and water flow under the influence of gradients in hydrostatic pressure, ion chemical potential, and electrical potential (voltage), leading to solvent flow, ionic fluxes and ionic current. At the outer surfaces of the membranes, electrical double layers (EDLs) are formed (Donnan layers). When a current flows through the membrane, we argue that besides the positive Joule heating in the bulk of the membrane and in the electrolyte outside the membrane, there is also negative Joule heating in one of the EDLs. We define Joule heating as the inner product of the two vectors current and field strength. Also when fluid flows through a charged membrane, at one side of the membrane there is pressure-related cooling, due to the osmotic and hydrostatic pressure differences across the EDLs.

P. M. Biesheuvel; D. Brogioli; H. V. M. Hamelers

2014-02-06

171

Nonlinear ion acoustic waves in multi-ion species plasmas at low electron to ion temperature ratios  

NASA Astrophysics Data System (ADS)

The nonlinear evolution of ion acoustic waves in multi-ion species plasmas is studied in the context of stimulated Brillouin scattering. With the aid of Vlasov simulations, multi-wavelength systems are investigated over a range of ratios of electron to ion temperatures relevant to current inertial confinement fusion experiments. The impact of nonlinear effects, such as harmonic generation, ion acoustic wave decay and both electron and ion trapping, and the interplay between the comparably damped fast and slow ion acoustic wave modes are demonstrated. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the Laboratory Research and Development Program at LLNL under project tracking code 12-ERD-061.

Chapman, Thomas; Berger, Richard; Williams, Edward; Cohen, Bruce; Brunner, Stephan

2012-10-01

172

Structural Insight into the Ion-Exchange Mechanism of the Sodium/Calcium Exchanger  

SciTech Connect

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.

Liao, Jun; Li, Hua; Zeng, Weizhong; Sauer, David B.; Belmares, Ricardo; Jiang, Youxing (UTSMC)

2012-06-19

173

Ecosystem-atmosphere CO 2 exchange: interpreting signals of change using stable isotope ratios  

Microsoft Academic Search

Changes in the concentration and stable isotope ratio of atmospheric CO2 can be used to study variations in the net exchange of carbon dioxide in terrestrial ecosystems (net difference between total photosynthesis and respiration). Changes in the timing of seasonal fluctuations in atmospheric CO2 concentration have suggested that net uptake of carbon dioxide has been increasing in northern latitude ecosystems

Lawrence B. Flanagan; James R. Ehleringer

1998-01-01

174

Truly incomplete and complex exchanges in prematurely condensed chromosomes of human fibroblasts exposed in vitro to energetic heavy ions  

NASA Technical Reports Server (NTRS)

Confluent human fibroblast cells (AG1522) were irradiated with gamma rays, 490 MeV/nucleon silicon ions, or iron ions at either 200 or 500 MeV/nucleon. The cells were allowed to repair at 37 degrees C for 24 h after exposure, and a chemically induced premature chromosome condensation (PCC) technique was used to condense chromosomes in the G2 phase of the cell cycle. Incomplete and complex exchanges were analyzed in the irradiated samples. To verify that chromosomal breaks were truly unrejoined, chromosome aberrations were analyzed using a combination of whole-chromosome specific probes and probes specific for the telomere region of the chromosome. Results showed that the frequency of unrejoined chromosome breaks was higher after irradiation with the heavy ions of high LET, and consequently the ratio of incomplete to complete exchanges increased steadily with LET up to 440 keV/microm, the highest LET included in the present study. For samples exposed to 200 MeV/nucleon iron ions, chromosome aberrations were analyzed using the multicolor FISH (mFISH) technique, which allows identification of both complex and truly incomplete exchanges. Results of the mFISH study showed that 0.7 and 3 Gy iron ions produced similar ratios of complex to simple exchanges and incomplete to complete exchanges; these ratios were higher than those obtained after exposure to 6 Gy gamma rays. After 0.7 Gy of iron ions, most complex aberrations were found to involve three or four chromosomes, which is a likely indication of the maximum number of chromosome domains traversed by a single iron-ion track.

Wu, Honglu; Durante, Marco; Furusawa, Yoshiya; George, Kerry; Kawata, Tetsuya; Cucinotta, Francis A.

2003-01-01

175

High performance DNA purification using a novel ion exchange matrix.  

PubMed

Ion exchange chromatography has emerged as a reliable alternative to classic CsCl-ethidium bromide gradients for isolating nucleic acids of the highest purity. A plasmid purification method based on a unique anion exchange membrane (IEXM) was developed for the production of superior quality plasmids. This method was simpler and more efficient than conventional bead-based methods. Plasmids were extracted from bacterial cells through alkaline lysis. The crude lysate was clarified by a sequential filtration device that not only removed cell debris but micellar aggregates as well. The clarified lysate was mixed with an extraction solution and loaded into a spin column containing IEXM. Binding, washing, and elution conditions were optimized to achieve efficient isolation of plasmids from the impurities. IEXM had an exceedingly high dynamic binding capacity, excellent selectivity, and a near 100% recovery for plasmids. The binding capacity for pUC19 was 2.93 mg/cm(3) of IEXM, which is several times greater than the values for conventional ion exchange beads. The superior selectivity of the method was reflected in the extremely low levels of endotoxin, and thus it is well-suited for critical applications in eukaryotic systems. PMID:19137108

Yang, Yu; Hebron, Haroun R; Hang, Jun

2008-07-01

176

Ion-exchange equilibrium of N-acetyl-d-neuraminic acid on a strong anionic exchanger.  

PubMed

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. PMID:25863634

Wu, Jinglan; Ke, Xu; Zhang, Xudong; Zhuang, Wei; Zhou, Jingwei; Ying, Hanjie

2015-09-15

177

Donnan dialysis with ion-exchange membranes. 3: Diffusion coefficients using ions of different valence  

SciTech Connect

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.

Miyoshi, Hirofumi [Osaka Prefecture Univ., Sakai, Osaka (Japan). Research Inst. for Advanced Science and Technology] [Osaka Prefecture Univ., Sakai, Osaka (Japan). Research Inst. for Advanced Science and Technology

1999-01-01

178

Assessment of cadmium in aquatic sediment using dialysis samplers with ion-exchange-resin collection  

SciTech Connect

Simultaneously extracted metals (SEM) and acid volatile sulfide (AVS) show the potential for toxicity on the basis of their ratio. Accordingly, the authors spiked cadmium in a range for which Cd/AVS ratios were from 0.2 to 10 in the sediment with its weight about 8 kg in each batch. Dialysis samplers with a cation ion-exchange resin (Dowex 50W-X4) collection were used in a laboratory for the determination of free cadmium concentrations in pore water of the collected sediment. When equilibrium was reached among cadmium in pore water, sediment, and ion-exchange resin, cadmium exchanged onto resin phase was regenerated with 1 N hydrochloric acid (OPTIMA grade) and determined using an atomic absorption spectrophotometer (Zeeman 5000) with a graphite furnace accessory. Cadmium determined using the dialysis sampler is considered as free cadmium which is related to the metal bioavailability toward aquatic biota. The developed methodology provides a new technique for assessment of free metal in aquatic sediment systems.

Shi, B. [Kimberly-Clark Corp., Neenah, WI (United States). Environmental Technology; Allen, H.E. [Univ. of Delaware, Newark, DE (United States). Dept. of Civil and Environmental Engineering; Desnoyers, C. [ERM Program Management Co., Exton, PA (United States)

1998-05-01

179

Diffusional transport of ions in plasticized anion-exchange membranes.  

PubMed

Diffusional transport properties of hydrophobic anion-exchange membranes were studied using the polymer inclusion membrane (PIM). This class of membranes is extensively used in the chemical sensor and membrane based separation processes. The samples of PIM were prepared by physical containment of the trioctylmethylammonium chloride (Aliquat-336) in the plasticized matrix of cellulose triacetate (CTA). The plasticizers 2-nitrophenyl octyl ether, dioctyl phthalate, and tris(2-ethylhexyl)phosphate having different dielectric constant and viscosity were used to vary local environment of the membrane matrix. The morphological structure of the PIM was obtained by atomic force microscopy and transmission electron microscopy (TEM). For TEM, platinum nanoparticles (Pt nps) were formed in the PIM sample. The formation of Pt nps involved in situ reduction of PtCl(6)(2-) ions with BH(4)(-) ions in the membrane matrix. Since both the species are anions, Pt nps thus formed can provide information on spatial distribution of anion-exchanging molecules (Aliquat-336) in the membrane. The glass transitions in the membrane samples were measured to study the effects of plasticizer on physical structure of the membrane. The self-diffusion coefficients (D) of the I(-) ions and water in these membranes were obtained by analyzing the experimentally measured exchange rate profiles of (131)I(-) with (nat)I(-) and tritiated water with H(2)O, respectively, between the membrane and equilibrating solution using an analytical solution of Fick's second law. The values of D(I(-)) in membrane samples with a fixed proportion of CTA, plasticizer, and Aliquat-336 were found to vary significantly depending upon the nature of the plasticizer used. The comparison of values of D with properties of the plasticizers indicated that both dielectric constant and viscosity of the plasticizer affect the self-diffusion mobility of I(-) ions in the membrane. The value of D(I(-)) in the PIM samples did not vary significantly with concentration of Aliquat-336 up to 0.5 mequiv g(-1), and thereafter D(I(-)) increased linearly with Aliquat-336 concentration in the membrane. The self-diffusion coefficients of water D(H(2)O) in PIM samples were found to be 1 order of magnitude higher than the value of D(I(-)) and varied slightly depending upon the plasticizer present in the membrane. It was observed in electrochemical impedance spectroscopic studies of the PIM samples that diffusion mobility of NO(3)(-) ions was 1.66 times higher than that of I(-) ions, and diffusion mobility of SO(4)(2-) ions was half of that for I(-) ions. The theoretical interpretation of experimental counterions exchange rate profiles in terms of the Nernst-Planck equation for interdiffusion also showed higher diffusion mobility of NO(3)(-) ions in the PIM than Cl(-), I(-), and ClO(4)(-) ions, which have comparable diffusion mobility. PMID:21513289

Kumar, Rakesh; Pandey, Ashok K; Sharma, Manoj K; Panicker, L V; Sodaye, Suparna; Suresh, G; Ramagiri, Shobha V; Bellare, Jayesh R; Goswami, A

2011-05-19

180

Ammonium removal from digested sludge liquors using ion exchange.  

PubMed

Liquors arising from the dewatering of digested sludge typically contain ammonium levels in the range 200-700mgl(-1) NH(4)(+)-N. These liquors are frequently recycled to the head of the wastewater treatment works (WwTW) untreated and can constitute >25% of the total nitrogen load entering the works at inlet. This paper investigates the use of a clay-based material, MesoLite, as an ion exchange medium for ammonium removal from recycle streams. Pilot-scale studies performed at Didcot WwTW, part of the Thames Water wastewater treatment network, indicate that MesoLite is highly selective for the ammonium ion. Results show that >95% of ammonium was removed from belt press liquors with an initial ammonium nitrogen concentration >600mgl(-1), with an overall ion exchange capacity >51g NH(4)(+)-Nkg(-1) medium and this resulted in an operating capacity in the range 27-36gNH(4)(+)-Nkg(-1). PMID:17161445

Thornton, A; Pearce, P; Parsons, S A

2007-01-01

181

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

SciTech Connect

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.

Hui Yawei; Schultz, David R. [Physics Division, Oak Ridge National Laboratory Bldg. 6010, Oak Ridge, TN 37831 (United States); Kharchenko, Vasili A. [Physics Department, University of Connecticut 2152 Hillside Road, U-3046, Storrs, CT 06269 (United States); Stancil, Phillip C. [Department of Physics and Astronomy and the Center for Simulational Physics, University of Georgia, Athens, GA 30602 (United States); Cravens, Thomas E. [Department of Physics and Astronomy, University of Kansas 1251 Wescoe Hall Drive, Lawrence, KS 66045 (United States); Lisse, Carey M. [Johns Hopkins University Applied Physics Laboratory SD/SRE, MP3-E167, 11100 Johns Hopkins Road, Laurel MD 20723 (United States); Dalgarno, Alexander [Harvard-Smithsonian Center for Astrophysics 60 Garden Street, Cambridge, MA 02138 (United States)], E-mail: huiy@ornl.gov, E-mail: schultzd@ornl.gov, E-mail: kharchenko@phys.uconn.edu, E-mail: stancil@physast.uga.edu, E-mail: cravens@ku.edu, E-mail: carey.lisse@jhuapl.edu, E-mail: adalgarno@cfa.harvard.edu

2009-09-10

182

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

SciTech Connect

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.

Hui, Yawei [ORNL; Schultz, David Robert [ORNL; Kharchenko, Vasili A [ORNL; Stancil, Phillip C. [University of Georgia, Athens, GA; Cravens, Thomas E. E. [University of Kansas; Lisse, Carey M. [Johns Hopkins University; Dalgarno, A. [Harvard-Smithsonian Center for Astrophysics

2009-01-01

183

Investigation of Alkali Ion Exchange Processes in Na-Al-Si Glass Using Ion beam Techniques  

NASA Astrophysics Data System (ADS)

Glass and ceramic waste forms are proposed for the stabilization and immobilization of high level wastes. Recent findings show that Na ion exchange reaction can effectively increase the release of radionuclides from the glass matrix. We investigated the Na ion exchange processes and mechanisms using Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). The glass samples with fixed Na_2O and variable Al_2O3 concentrations were exposed to different times at 23^oC in a single pass flow-through apparatus, which contained aqueous D2 ^18O solution, supersaturated with respect to amorphous silica. The results show that the Na exchange rate is much higher than the matrix dissolution rate. On the basis of the depth distributions of Na, D, and ^18O, three different zones (reaction, transition and diffusion zones) were identified. The samples with higher amounts of Al content have a significantly narrower reaction zone than the low Al content glass samples.

Shutthanandan, V.; Thevuthasan, S.; Baer, D. R.; Icenhower, J. P.; Engelhard, M. H.; McGrail, B. P.

2001-03-01

184

Position-specific measurement of oxygen isotope ratios in cellulose: Isotopic exchange during heterotrophic cellulose synthesis  

NASA Astrophysics Data System (ADS)

We describe the first reported method for the measurement of oxygen isotope ratios at each position in the glucose units of the cellulose molecule. The overall process comprises a series of synthetic organic sequences, by which ?-cellulose is hydrolysed to glucose, and oxygen atoms at specific positions in the glucose molecule are removed in samples of benzoic acid for measurement of ?18O. Values of ?18O at specific positions in cellulose are calculated from these ?18O values and the overall ?18O value of the cellulose. We apply the method to determine the degree to which oxygen atoms at each position undergo isotopic exchange with water during heterotrophic cellulose synthesis, such as occurs in the cambium of trees. To do this we extract ?-cellulose from wheat seedlings germinated in the dark in aqueous media of differing oxygen isotope ratios. Results indicate that oxygen atoms at positions 5 and 6 (O-5 and O-6 respectively) undergo around 80% exchange with medium water, O-3 undergoes around 50% exchange, and O-2 and O-4 do not undergo isotopic exchange. The results have important implications for extracting palaeoclimatic records from oxygen isotope time series obtained from tree ring cellulose. As O-5 and O-6 undergo significant exchange with medium water during heterotrophic cellulose synthesis, oxygen isotopes at these positions in tree ring cellulose should carry a predominantly trunk (source) water signal. On the other hand, O-2 and O-4 should retain the isotopic signature of leaf water in tree ring cellulose. Our method therefore potentially enables the separate reconstruction of past temperature and humidity data from oxygen isotope ratios of tree ring cellulose - something that has hitherto not been possible. The measured degrees of isotopic exchange are to some extent unexpected and cannot be fully explained using current biochemical mechanisms, suggesting that knowledge of these processes is incomplete.

Waterhouse, John S.; Cheng, Shuying; Juchelka, Dieter; Loader, Neil J.; McCarroll, Danny; Switsur, V. Roy; Gautam, Lata

2013-07-01

185

Vitrification of cesium-contaminated organic ion exchange resin  

SciTech Connect

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.

Sargent, T.N. Jr. [Clemson Univ., SC (United States)

1994-08-01

186

Ion Exchange Testing with SRF Resin FY2012  

SciTech Connect

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.

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

2013-06-11

187

Improved brine recycling during nitrate removal using ion exchange.  

PubMed

Ion exchange technology is currently the best for removing nitrate from drinking water. However, problems related to the disposal of spent brine from regeneration of exhausted resins must be overcome so that ion exchange can be applied more widely and economically, especially in small communities. For this purpose, a novel spent brine recycling system using combined biological denitrification and sulfate reduction processes was developed for more efficient reuse of brine. A granular activated carbon (GAC) adsorption column was introduced as an additional step to prevent contamination of resins by bio-polymers and dissolved organics present in the bio-reactor effluent. Two upflow sludge blanket reactors (USBRs) were operated in series for 166 days to provide denitrification and sulfate reduction. The denitrification reactor provided a nitrate removal efficiency of 96% at a nitrate-N loading rate of 5.4 g NO3(-)-N/l d. The sulfate reduction efficiency of the sulfate reduction reactor remained approximately 62% at a sulfate loading rate of 1.8 g SO4(2-)/l d. Five ion exchange columns containing A520E resins were repeatedly operated in up to 25 cycles of service and regeneration using five kinds of brine: one virgin 3% NaCl and four differently recycled spent brines. Throughput decreased remarkably when the biologically recycled brine was not treated with the GAC column, probably due to the presence of bio-polymers and dissolved organic compounds. The sulfate reduction reactor placed after the denitrification step increased the bicarbonate concentration, which could be used as a co-regenerant with chloride. The inclusion of the sulfate reduction reactor into the conventional brine recycling system allowed more efficient reuse of brine, resulting in both reduced salt consumption and brine discharge. PMID:12188132

Bae, Byung-Uk; Jung, Yoo-Hoon; Han, Woon-Woo; Shin, Hang-Sik

2002-07-01

188

HEAT TRANSFER ANALYSIS FOR ION-EXCHANGE COLUMN SYSTEM  

SciTech Connect

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.

Lee, S.; King, W.

2011-05-23

189

Ion Exchange Testing with SRF Resin FY 2012  

SciTech Connect

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.

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

2014-07-02

190

Ion exchange separation of chromium from natural water matrix for stable isotope mass spectrometric analysis  

USGS Publications Warehouse

A method has been developed for separating the Cr dissolved in natural water from matrix elements and determination of its stable isotope ratios using solid-source thermal-ionization mass spectrometry (TIMS). The separation method takes advantage of the existence of the oxidized form of Cr as an oxyanion to separate it from interfering cations using anion-exchange chromatography, and of the reduced form of Cr as a positively charged ion to separate it from interfering anions such as sulfate. Subsequent processing of the separated sample eliminates residual organic material for application to a solid source filament. Ratios for 53Cr/52Cr for National Institute of Standards and Technology Standard Reference Material 979 can be measured using the silica gel-boric acid technique with a filament-to-filament standard deviation in the mean 53Cr/52Cr ratio for 50 replicates of 0.00005 or less. (C) 2000 Elsevier Science B.V. All rights reserved.

Ball, J.W.; Bassett, R.L.

2000-01-01

191

Enhanced gas-phase hydrogen-deuterium exchange of oligonucleotide and protein ions stored in an external multipole ion reservoir.  

PubMed

Rapid gas-phase hydrogen-deuterium (H-D) exchange from D(2)O and ND(3) into oligonucleotide and protein ions was achieved during storage in a hexapole ion reservoir. Deuterated gas is introduced through a capillary line that discharges directly into the low-pressure region of the reservoir. Following exchange, the degree of H-D exchange is determined using Fourier transform ion cyclotron resonance mass spectrometry. Gas-phase H-D exchange experiments can be conducted more than 100 times faster than observed using conventional in-cell exchange protocols that require lower gas pressures and additional pump-down periods. The short experimental times facilitate the quantitation of the number of labile hydrogens for less reactive proteins and structured oligonucleotides. For ubiquitin, we observe approximately 65 H-D exchanges after 20 s. Exchange rates of > 250 hydrogens s(-1) are observed for oligonucleotide ions when D(2)O or ND(3) is admitted directly into the external ion reservoir owing to the high local pressure in the hexapole. Partially deuterated oligonucleotide ions have been fragmented in the reservoir using infrared multiphoton dissociation (IRMPD). The resulting fragment ions show that exchange predominates at charged sites on the 5'- and 3'-ends of the oligonucleotide, whereas exchange is slower in the core. This hardware configuration is independent of the mass detector and should be compatible with other mass spectrometric platforms including quadrupole ion trap and time-of-flight mass spectrometers. PMID:10633235

Hofstadler, S A; Sannes-Lowery, K A; Griffey, R H

2000-01-01

192

Ion Exchange Chromatography and Mass Spectrometric Methods for Analysis of Cadmium-Phytochelatin (II) Complexes  

PubMed Central

In this study, in vitro formed Cd-phytochelatin (PC2) complexes were characterized using ion exchange chromatography (IEC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The ratio of both studied compounds as well as experimental conditions were optimized. The highest yield of the complex was observed under an applied concentration of 100 µg·mL?1 PC2 and 100 µg·mL?1 of CdCl2. The data obtained show that IEC in combination with MALDI-TOF is a reliable and fast method for the determination of these complexes. PMID:23538727

Merlos Rodrigo, Miguel Angel; Cernei, Natalia; Kominkova, Marketa; Zitka, Ondrej; Beklova, Miroslava; Zehnalek, Josef; Kizek, Rene; Adam, Vojtech

2013-01-01

193

On the chemical equilibration of strangeness-exchange reaction in heavy-ion collisions  

E-print Network

The strangeness-exchange reaction pi + Y -> K- + N is shown to be the dynamical origin of chemical equilibration for K- production in heavy-ion collisions up to beam energies of 10 A GeV. The hyperons occurring in this process are produced associately with K+ in baryon-baryon and meson-baryon interactions. This connection is demonstrated by the ratio K-/K+ which does not vary with centrality and shows a linear correlation with the yield of pions per participant. At incident energies above AGS this correlation no longer holds due to the change in the production mechanism of kaons.

J. Cleymans; A. Foerster; H. Oeschler; K. Redlich; F. Uhlig

2004-06-12

194

Magnetic Exchange Interaction between Rare-Earth and Mn Ions in Multiferroic Hexagonal Manganites  

E-print Network

Magnetic Exchange Interaction between Rare-Earth and Mn Ions in Multiferroic Hexagonal Manganites D the magnetic exchange coupling between the rare-earth and Mn ions. DOI: 10.1103/PhysRevLett.101.247601 PACS the rare-earth and Mn ions is respon- sible for the strong ME coupling that allows the control

195

Solid Phase Luminescence of Several Rare Earth Ions on Ion-Exchange Films  

NASA Technical Reports Server (NTRS)

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.

Tanner, Stephen P.; Street, Kenneth W., Jr.

1999-01-01

196

Extraction and ion-exchange behavior of mendelevium (II)  

SciTech Connect

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.

Guseva, L.I.; Tikhomirova, G.S.; Buklanov, G.V.; Pkhar, Z.Z.; Lebedev, I.A.; Katargin, N.V.; Myasoedov, B.F.

1988-09-01

197

FDM study of ion exchange diffusion equation in glass  

NASA Astrophysics Data System (ADS)

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.

Zhou, Zigang; Yang, Yongjia; Wang, Qiang; Sun, Guangchun

2009-05-01

198

Ion-exchange studies on poly-o-anisidine Sn(IV) phosphate nano composite and its application as Cd(II) ion-selective membrane electrode  

Microsoft Academic Search

An organic-inorganic composite, poly-o-anisidine Sn(IV) phosphate, was chemically synthesized by mixing ortho-anisidine into\\u000a gels of Sn(IV) phosphate with different mixing volume ratios. Studies on the effect of eluant concentration, elution behavior\\u000a and separation of metal ions were carried out to understand the ion-exchange capabilities. Due to Cd(II) selective nature\\u000a of composite, revealed by distribution studies, Cd(II) ion selective membrane electrode

Asif Ali Khan; Anish Khan

2010-01-01

199

Evaluation of Ion Exchange Materials in K Basin Floor Sludge and Potential Solvents for PCB Extraction from Ion Exchange Materials  

SciTech Connect

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 solvent extraction of PCB surrogates from simulant K Basin sludge is also given.

Schmidt, A.J.; Klinger, G.S.; Bredt, P.R.

1999-04-10

200

Comparison of inorganic ion exchange materials for removing cesium, strontium, and transuranic elements from K-basin water  

SciTech Connect

The work presented in this report was conducted by the Pacific Northwest National Laboratory (PNNL) under the Efficient Separations and Crosscutting Program (ESP), Office of Science and Technology, U.S. Department of Energy (DOE). The objective of this work was to investigate radionuclide uptake by several newly produced ion exchange materials under actual waste conditions, and to compare the performance of those materials with that of commercially available ion exchangers. The equilibrium uptake data presented in this report are useful for identifying potential materials that are capable of removing cesium and strontium from 105-KE Basin water. The data show the relative selectivities of the ion exchange materials under similar operating conditions. Additional flow studies are needed to predict material capacities and to develop complete ion exchange process flow sheets. The materials investigated in this study include commercially available ion exchangers such as IONSIV{reg_sign} IE-911 (manufactured by UOP), clinoptilolite (a naturally occurring zeolite), and materials produced on an experimental basis by AlliedSignal (biotites and nonatitanates), 3M (hexacyanoferrates), Selion Technologies, Inc. (hexacyanoferrates and titanates), and Texas A&M University (pharmacosiderites, biotites, and nonatitanates). In all, the performance of 14 ion exchange materials was evaluated at two solution-to-exchanger mass ratios (i.e., 10{sup 4} and 10{sup 5}) using actual 105-KE Basin water. Evaluation consisted of determining cesium and strontium batch distribution coefficients, loading, and decontamination factors. Actual 105-KE Basin water was obtained from a sample collected during the sludge dissolution work conducted by PNNL in FY 1996. This sample was taken from the bottom of the basin and contained significantly higher concentrations of the radioactive constituents than do samples taken from the top of the basin.

Brown, G.N.; Bontha, J.R.; Carson, K.J.; Elovich, R.J.; DesChane, J.R.

1997-10-01

201

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

202

Ion exchangers in radioactive waste management: natural Iranian zeolites.  

PubMed

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. PMID:16099667

Nilchi, A; Maalek, B; Khanchi, A; Ghanadi Maragheh, M; Bagheri, A; Savoji, K

2006-01-01

203

Low-level liquid waste decontamination by ion exchange  

SciTech Connect

Improved processes are being developed to treat contaminated liquid wastes that have been and continue to be generated at Oak Ridge National Laboratory. Both inorganic and organic ion-exchange methods have given promising results. Nickel and cobalt hexacyanoferrate(2) compounds are extremely selective for cesium removal, with distribution coefficients in excess of 10{sup 6} and remarkable insensitivity to competition from sodium and potassium. They tend to lose effectiveness at pH > {approximately}11, but some formulations are useful for limited periods of time up to pH {approximately}13. Sodium titanate is selective for strontium removal at high pH. The separations are so efficient that simple batch processes can yield large decontamination factors while generating small volumes of solid waste. A resorcinol-based resin developed at the Savannah River Site gave superior cesium removal, compared with other organic ion exchangers; the distribution coefficient was limited primarily by competition from potassium and was nearly independent of sodium. The optimum pH was {approximately}12.5. It was much less effective for strontium removal, which was limited by competition from sodium. 8 refs., 6 figs., 9 tabs.

Campbell, D.O.; Lee, D.D.; Dillow, T.A.

1991-12-01

204

Purification of lithium salts by CSA continuous countercurrent ion exchange  

SciTech Connect

A Continuous Countercurrent Ion Exchange (CCIX) process was developed for extraction of low levels of sodium, potassium, iron, and nickel from strong solutions of lithium chloride and lithium hydroxide. This study was done on a two-inch diameter CSA, Inc. CCIX pilot unit. A standard 8% cross-linked cation exchange resin was used. The feed was either 2[und M] LiCl or 2[und M] LiOH. The trace levels of contaminants had a slightly higher affinity for the resin than lithium and extracted 90% or better. Residual lithium on the resin was scrubbed of with KOH to render a lithium loss of less than 1% in the waste. Contaminants were stripped from the resin with 3[und M] HCl. Zinc was one metal that was not extracted because it formed an anionic chloride complex. However zinc and certain other metals were extracted with high efficiency using strong-base type resin. Other resins are available for efficient extraction of many other metal contaminants, but the alkali metals, Na and K, were dependent on the CCIX common cation exchange system.

Higgins, I.R. (CSA, Inc., Oak Ridge, TN (United States))

1986-12-01

205

Theorization on ion-exchange equilibria: activity of species in 2-D phases  

Microsoft Academic Search

Ion-exchange reactions are naturally occurring at soil and sediment\\/water interphases, determining soil fertility and water quality. These ion-exchange reactions with inorganic and organic exchangers are applied to chemical analysis, recovery of useful ions from low-grade ores (potentially from sea water), water purification including the preparation of “ultrapure” water, production of foods and medicines, therapy, and other uses. It is important

Hiroki Tamura

2004-01-01

206

Programmatic Re-Evaluation of Ion Exchange as a 1st Generation ITP Replacement  

SciTech Connect

This re-evaluation differs from previous work in that (1) the Ion Exchange option was evaluated from a standpoint assuming that ITP would never start up, thus Ion Exchange was the only viable option, (2) the DOE prescribed balanced assumptions were quite different than the WSRC Assumptions used previously, and (3) other Site events and changes within HLWM have tended to reduce the disadvantages of Ion Exchange relative to ITP as the first generation salt decontamination process.

Scott, A.B. [Westinghouse Savannah River Company, AIKEN, SC (United States)

1998-09-01

207

Dependence of Heat and Particle Transport on the Ratio of the Ion and Electron Temperatures  

SciTech Connect

Experiments in high confinement (H-mode) plasmas on the DIII-D tokamak show that the heat and particle transport are sensitive to the ratio of the ion and electron temperatures. Increasing the ion-to-electron temperature ratio decreases the electron and ion heat transport and the particle transport regardless of which temperature is being varied. A likely explanation of these results is the dependence of the ion-temperature-gradient instability on the ratio of the ion and electron temperatures. {copyright} {ital 1999} {ital The American Physical Society}

Petty, C.C.; Groebner, R.J.; Luce, T.C.; Staebler, G.M. [General Atomics, San Diego, California 92186-5608 (United States)] [General Atomics, San Diego, California 92186-5608 (United States); Wade, M.R. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-2009 (United States)] [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-2009 (United States); Kinsey, J.E. [Lehigh University, Bethlehem, Pennsylvania 18015 (United States)] [Lehigh University, Bethlehem, Pennsylvania 18015 (United States)

1999-11-01

208

Sodalite ion exchange in polyethylene oxide oligomer solvents Gina M. Canfield,a  

E-print Network

Sodalite ion exchange in polyethylene oxide oligomer solvents Gina M. Canfield,a Michael Bizimisb and rare earth ions. Ethylene oxide-based oligomers (polyethylene glycol, polyethylene glycol methyl ether

Latturner, Susan

209

Selective exchange of divalent transition metal ions in cryptomelane-type manganic acid with tunnel structure  

SciTech Connect

The ion-exchange selectivity of divalent transition metal ions on cryptomelane-type manganic acid (CMA) with tunnel structure has been studied using the distribution coefficients ([ital K][sub [ital d

Tsuji, M. (Department of Chemistry, Faculty of Science, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152 (Japan)); Komarneni, S. (Materials Research Laboratory and Department of Agronomy, The Pennsylvania State University, University Park, Pennsylvania 16802-4801 (United States))

1993-03-01

210

Ultrasmall fluorescent ion-exchanging nanospheres containing selective ionophores.  

PubMed

We present a convenient precipitation procedure to fabricate ultrasmall fluorescent ion-selective nanosensors that operate on the basis of bulk ion-exchange sensing principles. The nanosphere matrix is composed of bis(2-ethylhexyl) sebacate (DOS) and a triblock copolymer Pluronic(®) F-127, which also functions as a surfactant to stabilize the nanoparticle. The particles can be prepared easily in large quantity without resorting to further complicated purification. Dynamic light scattering shows that these particles have a monodisperse size distribution with an average diameter of ?40 nm, suggesting that the nanoparticles are among the smallest ionophore-based ion-selective nanosensors reported to date. A newly reported oxazinoindoline (Ox) as well as a Nile blue derivative (chromoionophore I) was used as a chromoionophore. Na(+)- and H(+)-selective nanospheres were characterized by absorbance and fluorescence spectroscopy. Owing to the very small size of the nanospheres, the suspension containing the particles is transparent. In the additional presence of the pH indicator HPTS, spectroscopic interrogation of pH and Na(+) in the same sample was demonstrated. As an example, the nanospheres were used to measure the Na(+) level in commercial mineral waters, and the results showed good agreement with atomic absorption spectroscopy (AAS). PMID:24020858

Xie, Xiaojiang; Mistlberger, Günter; Bakker, Eric

2013-10-15

211

Exchange bias in polycrystalline magnetite films made by ion-beam assisted deposition  

NASA Astrophysics Data System (ADS)

Iron oxide films were produced using ion-beam-assisted deposition, and Raman spectroscopy and x-ray diffraction indicate single-phase magnetite. However, incorporation of significant fractions of argon in the films from ion bombardment is evident from chemical analysis, and Fe/O ratios are lower than expected from pure magnetite, suggesting greater than normal disorder. Low temperature magnetometry and first-order reversal curve measurements show strong exchange bias, which likely arises from defects at grain boundaries, possibly amorphous, creating frustrated spins. Since these samples contain grains ˜6 nm, a large fraction of the material consists of grain boundaries, where spins are highly disordered and reverse independently with external field.

Kaur, Maninder; Jiang, Weilin; Qiang, You; Burks, Edward C.; Liu, Kai; Namavar, Fereydoon; McCloy, John S.

2014-11-01

212

Exchange bias in polycrystalline magnetite films made by ion-beam assisted deposition  

SciTech Connect

Iron oxide films were produced using ion-beam-assisted deposition, and Raman spectroscopy and x-ray diffraction indicate single-phase magnetite. However, incorporation of significant fractions of argon in the films from ion bombardment is evident from chemical analysis, and Fe/O ratios are lower than expected from pure magnetite, suggesting greater than normal disorder. Low temperature magnetometry and first-order reversal curve measurements show strong exchange bias, which likely arises from defects at grain boundaries, possibly amorphous, creating frustrated spins. Since these samples contain grains ?6?nm, a large fraction of the material consists of grain boundaries, where spins are highly disordered and reverse independently with external field.

Kaur, Maninder; Qiang, You [Department of Physics, University of Idaho, Moscow, Idaho 83844 (United States); Jiang, Weilin [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Burks, Edward C.; Liu, Kai [Department of Physics, University of California, Davis, California 95616 (United States); Namavar, Fereydoon [University of Nebraska Medical Center, Omaha, Nebraska 68198 (United States); McCloy, John S. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 98163 (United States)

2014-11-07

213

Photoluminescence response of terbium-exchanged MFI-type materials to Si/Al ratio, texture, and hydration state.  

PubMed

Terbium-exchanged MFI zeolite type materials, i.e., microporous-mesoporous Zeotile-1 with the Si/Al ratio in the range 33-200, Zeogrid with the Si/Al ratio of 75, and nanocrystalline MFI with the Si/Al ratio of 75, were prepared via an ion exchange procedure. All of these zeolites were investigated by means of time-resolved photoluminescence techniques in various hydration states: as-synthesized (hydrated), calcined (heated at 450 degrees C in air), and rehydrated (after a six-month exposure to the atmospheric moisture). The photoluminescence decays and spectra were analyzed by discrete exponential fitting, distribution lifetimes analysis, and area-normalized time-resolved photoluminescence spectra. The results sustained a single average terbium species coordinated to both water molecules and framework oxygens in the hydrated zeolites. The framework contribution increased with the Si/Al ratio in Zeotile-1 and was greatest for the nanocrystalline MFI zeolite. For the calcined Zeotile-1 and Zeogrid, two main terbium species of different environments were found. For the nanocrystalline Tb3+-MFI, a distinct number of species could not be inferred, indicating a more heterogeneous distribution. Rehydration further differentiated among the Tb3+-exchanged zeolites. Photoluminescence line shape and decay of Tb3+-Zeotile-1 were between those of the hydrated and calcined states indicating a slow rehydration rate in contrast with the photoluminescence properties of Tb3+-MFI, which fully recovered the values of the hydrated state. Tb3+-Zeogrid presented an intermediate case: while the PL line shape was fully restored to that measured for the hydrated sample, the decay was still longer than that measured with the hydrated sample. Terbium photoluminescence response related to zeolite texture, Si/Al ratio, and hydration state suggest different sitting and location of terbium in Zeotile-1, Zeogrid, and nanocrystalline MFI materials. In mesoporous Zeotile-1 and Zeogrid, the results sustained two types of terbium sites: one on the internal surface of mesopores, the other inside the pores, while for the nanocrystalline MFI, terbium sites inside the pores predominate. PMID:17181210

Tiseanu, Carmen; Kumke, Michael U; Parvulescu, Vasile I; Gessner, André; Gagea, Bogdan C; Martens, Johan A

2006-12-28

214

Sorption of uranyl ions from various acido systems by amphoteric epoxy amine ion-exchange resins  

SciTech Connect

Sorption of uranyl ions by epoxy amine ampholytes with N-monomethylenephosphonic acid groups modified with pyridine or quaternary ammonium groups was studied under dynamic conditions. Heterocyclic nitrogen favors sorption of uranyl ion from fluoride, sulfate, and fluoride-sulfate solutions. The ESR studies of mono- and bimetallic forms of nitrogen-containing ampholytes with copper(II) as paramagnetic marker revealed the characteristics of uranium(VI) interaction with cation- and anion-exchange groups and its dependence on the fluoride content in solution.

Rychkov, V.N.; Radionov, B.K.; Molochnikov, L.S. [and others

1995-03-01

215

Small Column Ion Exchange Design and Safety Strategy  

SciTech Connect

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 includes provisions for equipment maintenance including remote handling. The design includes a robust set of nuclear safety controls compliant with DOE Standard (STD)-1189, Integration of Safety into the Design Process. The controls cover explosions, spills, boiling, aerosolization, and criticality. Natural Phenomena Hazards (NPH) including seismic event, tornado/high wind, and wildland fire are considered. In addition, the SCIX process equipment was evaluated for impact to existing facility safety equipment including the waste tank itself. SCIX is an innovative program which leverages DOE's technology development capabilities to provide a basis for a successful field deployment.

Huff, T.; Rios-Armstrong, M.; Edwards, R.; Herman, D.

2011-02-07

216

Studies on synthetic inorganic ion exchangers-V: preparation, properties and ion-exchange behaviour of amorphous and crystalline thorium tungstate.  

PubMed

Amorphous and crystalline thorium tungstate have been prepared by mixing 0.1M thorium nitrate and 0.1M sodium tungstate under different conditions. The physico-chemical properties, chemical stability, composition, TGA, DTA, X-ray, infrared absorption and ion-exchange behaviour of thorium-tungstate are reported and discussed. Distribution coefficients of metal ions on thorium tungstate have been determined at pH 2-3 and 5.5-6.5. Selective ion-exchange separations of bismuth and mercury from other metal ions have been achieved on a column of thorium tungstate. PMID:18961820

De, A K; Chowdhury, K

1976-02-01

217

The effect of ions on sodium-calcium exchange in salamander rods.  

PubMed Central

1. The influence of external cations on the rate at which a Ca2+ load was eliminated in exchange for external Na+ was studied by measuring the inward current associated with Na+-Ca2+ exchange in salamander rods. 2. In Ringer solution the exchange current saturated at a well-defined level of about 20 pA at 20 degrees C. 3. The saturation level of exchange current, j(sat), was increased by lowering the external concentrations of H+, Ca2+, Mg2+ and K+; it was decreased by raising the external concentration of these ions or by lowering [Na+]O. 4. J(sat) varied approximately as [Na+]O2.4 between 35 and 110 mM-Na+. 5. The inhibitory constants for external Ca2+ and Mg2+ were about 1 and 4 mM, respectively. 6. An acid pH decreased j(sat) and an alkaline one increased it; the shape of the relation between current and pH suggests that one inhibitory proton combines between pH 8 and 10 and a pair combine between pH 6 and 7. 7. Removing K+, Mg2+, and Ca2+, and increasing the pH from 7.5 to 10 increased the measured exchange current from 20 to ca. 100 pA. 8. The integral of the Na+-Ca2+ exchange current varied with the Ca2+ load but was largely independent of external ionic changes in spite of large changes in j(sat). The apparent Na+-Ca2+ exchange ratio remained at a little under 3 over a wide range of conditions. 9. The constancy of the integral of the exchange current was brought about by reciprocal variations of the amplitude and duration of the current transient. Records in different solutions could usually be matched by scaling amplitude and time by reciprocal factors. 10. Increasing Nai+ by allowing large light-sensitive currents to flow in low-Ca2+ solutions affected the Na+-Ca2+ exchange transient in a different way from lowering [Na+]o or raising [Ca2+]o, etc. In an Na+-rich rod there was little reduction in j(sat) but the response was prolonged and larger Ca2+ loads were needed to reach saturation. Analysis in terms of a simple model indicated that a substantial Na+ load might reduce the apparent affinity of the internal pumping sites for Ca2+ by a factor of 10. 11. An attempt is made to relate these findings to a model of Na+-Ca2+ exchange. PMID:2451009

Hodgkin, A L; Nunn, B J

1987-01-01

218

STUDY OF INDUSTRIAL ION EXCHANGE SEPARATION OF RARE EARTH ELEMENTS BY EDTA COPPER METHOD. VII. MODELS OF INDUSTRIAL ION EXCHANGE TOWERS  

Microsoft Academic Search

Two new models of ion exchange towers were constructed: one hopper type, ; the other cylinder type\\/su Results of tests on the scale models indicate they can ; be scaled-up for industrial processes. (P.C.H.);

Nishigori

1961-01-01

219

Strontium adsorption from nitrite solutions using inorganic ion exchangers  

SciTech Connect

The potential use of inorganic ion exchangers to remove radioisotopes such as cesium and strontium for liquid wastes is well-documented. Materials such as sodium titanate have excellent adsorption properties for these elements, but their application is hampered by the poor mechanical properties of the commercially available materials. Powdered sodium titanate has been incorporated into hydrous titanium oxide microspheres produced by an internal gelation technique. The adsorption of Sr{sup ++} from 0.10 M NaNO{sub 3} has been measured as a function of pH. Kinetic data and loading capacity have also been evaluated. These data will be compared with data for pure hydrous titanium oxide and commercially available sodium titanate to determine the feasibility of using the doped microspheres for the removal of strontium from nitrate wastes.

Cox, J.M.; Purdy, L.K.; Ensor, D.D.; Collins, J.L. [Tennesse Technological Univ., Cookeville, TN (United States); [Oak Ridge National Lab., TN (United States)

1997-12-31

220

Influence of the ion/neutral atom mass ratio on the damping of electrostatic ion-cyclotron waves  

NASA Technical Reports Server (NTRS)

The damping of electrostatic ion-cyclotron waves by ion-neutral collisions was studied in a single-ended Q machine. The amplitudes of K(+) and Cs(+) electrostatic ion-cyclotron waves were measured as a function of neutral pressure in helium, neon, argon, krypton, and xenon. For each ion/neutral atom combination, the electrostatic ion-cyclotron wave amplitude maximizes at a neutral pressure that scales monotonically with the m(+)/m(n) mass ratio. This result is interpreted by considering the dynamics of elastic collisions between the ions and the neutral atoms.

Suszcynsky, D. M.; Cartier, S. L.; D'Angelo, N.; Merlino, R. L.

1987-01-01

221

Theoretical considerations for anticipating of function analysis on a gradient index-lens fabrication through double ion-exchange process.  

PubMed

Based on precise and detailed theoretical examination of diffusion equation analysis, two-step Ag(+)-Na(+) and Na(+)-Ag(+) ion-exchange parameters were optimized in order to fabricate a gradient index (GRIN) lens in the BK7 glass rod. Using the diffusion equation, the impact of the concentration ratio of the exchanged ion during the first and second steps was examined in detail. Then, based on the calculated effective parameters such as concentration ratio and immersion time, a fabrication process was proposed. We managed to get the optimum parameters (the bath stop time, temperature, and length) to make a quarter pitch lens. As a result, some samples of the GRIN lens were fabricated and tested successfully. Theoretical considerations and experimental results are presented. PMID:22968265

Zakeri, Banafsheh; Sabatyan, Arash

2012-09-10

222

Peptide Orientation Affects Selectivity in Ion-Exchange Chromatography  

SciTech Connect

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.

Alpert, Andrew J.; Petritis, Konstantinos; Kangas, Lars J.; Smith, Richard D.; Mechtler, Karl; Mitulovic, Goran; Mohammed, Shabaz; Heck, Albert J.

2010-06-15

223

Peptide Orientation Affects Selectivity in Ion-Exchange Chromatography  

SciTech Connect

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.

Alpert, Andrew J.; Petritis, Konstantinos; Kangas, Lars J.; Smith, R. D.; Mechtler, Karl; Mitulovic, Goran; Mohammed, Shabaz; Heck, Albert J.

2010-06-15

224

Truly Incomplete and Complex Chromosomal Exchanges in Human Fibroblast Cells Exposed In Situ to Energetic Heavy Ions  

NASA Technical Reports Server (NTRS)

Confluent human fibroblast cells (AG 1522) were irradiated with gamma rays, 490 MeV/nucleon Si, or with Fe ions at either 200 or 500 MeV/nucleon. The cells were allowed to repair at 37 C for 24 hours after exposure, and a chemically induced premature chromosome condensation (PCC) technique was used to condense chromosomes in the G2 phase of the cell cycle. Incomplete and complex exchanges were analyzed in the irradiated samples. In order to verify that chromosomal breaks were truly unrejoined, chromosome aberrations were analyzed using a combination of whole chromosome specific probes and probes specific for the telomere region of the chromosome. Results showed that the frequency of unrejoined chromosome breaks was higher after high-LET radiation, and consequently, the ratio of incomplete to complete exchanges increased steadily with LET up to 440 keV/micron, the highest LET value in the present study. For samples exposed to 200 MeV/nucleon Fe ions, chromosome aberrations were analyzed using the multicolor FISH (mFISH) technique that allow identification of both complex and truly incomplete exchanges. Results of the mFISH study showed that 0.7 and 3 Gy dose of the Fe ions produced similar ratios of complex to simple exchanges and incomplete to complete exchanges, values for which were higher than those obtained after a 6 Gy gamma exposure. After 0.7 Gy of Fe ions, most complex aberrations were found to involve three or four chromosomes, which is a likely indication of the maximum number of chromosome domains traversed by a single Fe ion track.

Wu, Honglu; Durante, marco; Furusawa, Yoshiya; George, Kerry; Kawata, Tetsuya; Cucinotta, Francis A.

2003-01-01

225

Evolution of ion-exchange: from Moses to the Manhattan Project to Modern Times  

Microsoft Academic Search

This article explores the history of ion-exchange from records of desalination in the Old Testament and the writings of Aristotle, to the identification of the phenomenon of ion-exchange by two English agricultural chemists, to the invention of suppressed conductivity by Small et al. [Anal. Chem. 54 (1975) 462]. It then focuses on the characteristics of the gradual and continuous evolution

Charles A. Lucy

2003-01-01

226

Possibility of improvement of boiler water treatment process—ion exchange vs. reverse osmosis  

Microsoft Academic Search

The boiler water in certain power plant is produced by chemical decarbonization, sand filtration, and ion exchange. Process ends with mixed bed ion exchange. The current boiler water treatment process is analyzed in terms of achieved water quality, quantity and quality of wastewater, and amount of chemicals needed. The main disadvantage of current process is consumption of large amount of

Dragana V. Kuki?; Marina B. Š?iban; Branka B. Mitrovi?; Jelena M. Prodanovi?; Vesna M. Vasi?; Darjana Ž. Iveti?; Mirjana G. Antov

2012-01-01

227

Spatial distributions of scandium in granules of different ion-exchangers  

Microsoft Academic Search

Scanning electron microscopy (SEM) and electron probe microanalysis (EPM) using an electron probe with high local sensitivity in nondestructive action on the sample, which is important in the analysis of ion-exchange materials, are efficient methods for physicochemical studies. SEM and EPM make it possible to study the spatial distribution of elements, characteristics of their absorption by ion-exchange materials, and establish

N. I. Komarova; T. V. Molchanova; V. V. Rodionov; L. I. Vodolazov

1992-01-01

228

Sorption of scandium by immobilized microdisperse forms of phosphorus-containing ion-exchangers  

Microsoft Academic Search

As a function of the problem involved, different brands of ion-exchangers are used for sorption extraction of scandium. Resins based on a macroporous styrene-divinylbenzene polymer matrix with a phosphonate ionogenic group are the most selective ion-exchangers with respect to this metal.

Y. V. Sokolova; G. M. Kurdyumov; A. V. Smirnov; M. S. Mezhirov

1992-01-01

229

Sorption of scandium by immobilized microdisperse forms of phosphorus-containing ion-exchangers  

SciTech Connect

As a function of the problem involved, different brands of ion-exchangers are used for sorption extraction of scandium. Resins based on a macroporous styrene-divinylbenzene polymer matrix with a phosphonate ionogenic group are the most selective ion-exchangers with respect to this metal.

Sokolova, Y.V.; Kurdyumov, G.M.; Smirnov, A.V.; Mezhirov, M.S.

1992-02-10

230

Ion exchange resins. (Latest citations from the EI Compendex*plus database). Published Search  

SciTech Connect

The bibliography contains citations concerning preparation, properties, and applications of ion exchange resins. Applications include water and waste treatment, chemical recovery, separation, purification, catalysis, desalination, and ore treatment. Regeneration and disposal of ion exchange resins are also covered. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1993-12-01

231

Ion exchange resins. (Latest citations from the EI Compendex*plus database). Published Search  

SciTech Connect

The bibliography contains citations concerning preparation, properties, and applications of ion exchange resins. Applications include water and waste treatment, chemical recovery, separation, purification, catalysis, desalination, and ore treatment. Regeneration and disposal of ion exchange resins are also covered. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1996-01-01

232

Removal of nitrogenous compounds from aqueous solution by ozonation and ion exchange  

Microsoft Academic Search

Experiments were conducted to investigate the ammonia, nitrite and nitrate removal from aqueous solution using ozonation and ion exchange. The operating variables of the combined ozonation and ion exchange processes include the pH, initial concentration of nitrogenous compounds and flow rate of aqueous solution. The effects of those variables on the removal efficiencies of the nitrogeneous compounds by ozonation, or

Sheng H. Lin; Chang L. Wu

1996-01-01

233

Modeling of Crystalline Silicotitanate Ion Exchange Columns Using Experimental Data from SRS Simulated Waste  

SciTech Connect

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.

Walker, D.D.

1999-03-15

234

Anion-exchange separations of metal ions in thiocyanate media.  

PubMed

The analytical potential of a weak-base macroreticular anion-exchange resin for the quantitative separation of metal ions in thiocyanate media is investigated and demonstrated. Distribution data are given for the sorption of some 25 metal ions from aqueous mixtures of potassium thiocyanate (1.0M or less) and 0.5M hydrochloric acid. The magnitude of the distribution data suggests many possible separations, some of which were quantitatively performed by procedures which are fast, simple and require only mild conditions. Representative separations are removal of traces of iron(III) and copper(II) from water samples prior to the determination of water hardness (calcium and magnesium), separation of nickel(II) from vanadium(IV) and the separation of thorium(IV) from titanium(IV). Some multicomponent separations are the separation of rare earths(III) and thorium(IV) from scandium(III) and the separation of rare earths(III) from iron(III) and uranium(VI). PMID:18960914

Fritz, J S; Kaminski, E E

1971-05-01

235

Silver structure environments in ion-exchanged silicate glasses studied by X-ray absorption fine structure.  

PubMed

X-ray absorption fine structure (XAFS) technique was used to analyze structural geometry of Ag atoms introduced into soda-lime silicate glass and soda aluminosilicate glass by ion-exchange method. The results show that Ag+ ion in soda aluminosilicate glass takes a coordination number of 1.6 with a Ag-O distance of 2.20 A when the ion-exchange ratio x is smaller than 0.47 and of 2.28 A when x is larger than 0.47. The introduced Ag+ ions are stabilized at the non-bridge oxygen (NBO) sites when x is lower than 0.47. The Na+ ions in AlO4 (O4 represents the bridging oxygen) sites are exchanged by Ag+ ions after all Na+ in NBO sites are replaced. The disorder of Ag-O coordination increases gradually with increasing x from 0.24 to 0.47 in soda aluminosilicate glass and increases dramatically when x is larger than 0.47. Ag+ ions takes a coordination number of 1.6 in the ion-exchanged soda-lime silicate glass and of 1.3 after subsequently thermal treatment with the same Ag-O distance of 2.14 A. Debye-Waller factor (DWF) of Ag-O coordination in soda aluminosilicate glass is higher than that in soda-lime silicate glass. Small Ag cluster has a reduced interatomic distance and a larger DWF. Ag nanoparticle in sample Ag-7 is in a state of tensile stress. PMID:19441594

Yang, X C; Li, W J; Dubiel, M; Huang, W H; Yano, T

2009-02-01

236

Disinfection of viable Pseudomonas stutzeri in ultrapure water with ion exchange resins  

Microsoft Academic Search

This study describes the disinfection of gram-negative bacteria, Pseudomonas stutzeri, isolated from ultrapure water (total organic carbon 5 ppb; effluent resistivity, > 18 M? cm at 25°C) with ion exchange resins using a batchwise procedure. A single bed of strong base anion exchange resin (SBAER) in OH? form shows disinfection ability; however, a bed of strong acid cation exchange resin

Nae Matsuda; Wataru Agui; Keizo Ogino; Norimichi Kawashima; Tokeru Watanabe; Hideki Sakai; Masahiko Abe

1996-01-01

237

Nanomaterials-Enhanced Electrically Switched Ion Exchange Process for Water Treatment  

SciTech Connect

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.

Lin, Yuehe; Choi, Daiwon; Wang, Jun; Bontha, Jagannadha R.

2009-01-01

238

Ion-exchange separation of scandium from thorium  

SciTech Connect

The influence of various factors on separation of thorium from scandium was investigated with the aid of a fractional factorial experiment. The most important characteristics of separation of thorium and scandium are the dynamic exchange capacity of the cation-exchanger for thorium (Y/sub 1/(DEC, meq Th/sup 4 +//g)) and the amount of scandium entering the effluent before breakthrough of thorium (Y/sub 2/ (%)), and the authors therefore adopted these characteristics as the response functions. The variable factors studied were X/sub 1/, the pH of the solution of thorium and scandium chlorides (2.7-3.3); X/sub 2/, the thorium concentration (6.4-14.0 g/liter); X/sub 3/, the flow rate of the solution through the column (0.2-0.8 ml/(min x cm/sup 2/)); X/sub 4/, the ratio of the height of the resin bed to the column diameter (4-10), generating the relation X/sub 4/ = X/sub 1/ x X/sub 2/ x X/sub 3/.

Kudryavskii, Yu.P.; Belkin, A.V.; Kazantsev, E.I.; Onosov, V.N.; Zonov, A.L.

1986-10-10

239

Ion-exchange selectivities of periderm and cuticular membranes toward alkali cations  

SciTech Connect

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.

Ersoz, M. [Univ. of Selcuk, Konya (Turkey); Duncan, H.J. [Univ. of Glasgow, Scotland (United Kingdom)

1994-08-01

240

Silver-coated ion exchange membrane electrode applied to electrochemical reduction of carbon dioxide  

Microsoft Academic Search

Silver-coated ion exchange membrane electrodes (solid polymer electrolyte, SPE) were prepared by electroless deposition of silver onto ion exchange membranes. The SPE electrodes were used for carbon dioxide (CO2) reduction with 0.2 M K2SO4 as the electrolyte with a platinum plate (Pt) for the counterelectrode. In an SPE electrode system prepared from a cation exchange membrane (CEM), the surface of

Y Hori; H Ito; K Okano; K Nagasu; S Sato

2003-01-01

241

Multivariant ion exchange: applications of weak-electrolyte resins in water purification  

Microsoft Academic Search

Weak-electrolyte ion exchange resins differ from strong-electrolyte resins in several aspects, including the dependence of exchange capacity on pH, the tendency to shrink or swell appreciably, and the stronger forces holding the counter-ion in the resin matrix. These differences lead to variations in sorption performance. A model has been developed based on the mass-action law for exchange of a multi-protic

Wheelwright

1982-01-01

242

Formation mechanism of silver nanocrystals made by ion irradiation of Na+<-->Ag+ ion-exchanged sodalime silicate glass  

NASA Astrophysics Data System (ADS)

Sodalime silicate glass surface layers were doped with up to 7.0 at.% Ag + ions by ion-exchange in a AgNO 3/NaNO 3 solution at 330-355°C. Ion irradiation using either 400 and 500 keV He, 1 MeV Ne or 2 MeV Xe was then used to induce the growth of metallic nanocrystals in the ion-exchanged region. The ion fluences ranged from 1.3×10 14 ions/cm2 to 1.1×10 17 ions/cm2. X-ray and electron diffraction show small Ag nanocrystals with a broad size distribution, up to a diameter of 10-15 nm, after irradiation. Optical transmission measurements show the characteristic surface plasmon resonance of metallic Ag around 420 nm. The absorption resonance sharpens and increases in strength with increasing ion irradiation fluence, indicating that both nanocrystal size and volume fraction increase with irradiation fluence. Depending on ion fluence, up to ˜15% of the ion-exchanged Ag + ions is incorporated in nanocrystals. From a systematic comparison of the degree of nanocrystal formation as a function of ion species, fluence and energy, it is concluded that nanocrystal formation is mainly caused by the atomic displacement energy loss component of the incoming ion beam; the electronic energy deposition component is less efficient.

Peters, D. P.; Strohhöfer, C.; Brongersma, M. L.; van der Elsken, J.; Polman, A.

2000-06-01

243

Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 1. Peptides to Proteins  

NASA Astrophysics Data System (ADS)

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.

Donohoe, Gregory C.; Khakinejad, Mahdiar; Valentine, Stephen J.

2015-04-01

244

Ion Exchange Technology Development in Support of the Urine Processor Assembly  

NASA Technical Reports Server (NTRS)

The urine processor assembly (UPA) on the International Space Station (ISS) recovers water from urine via a vacuum distillation process. The distillation occurs in a rotating distillation assembly (DA) where the urine is heated and subjected to sub-ambient pressure. As water is removed, the original organics, salts, and minerals in the urine become more concentrated and result in urine brine. Eventually, water removal will concentrate the urine brine to super saturation of individual constituents, and precipitation occurs. Under typical UPA DA operating conditions, calcium sulfate or gypsum is the first chemical to precipitate in substantial quantity. During preflight testing with ground urine, the UPA achieved 85% water recovery without precipitation. However, on ISS, it is possible that crewmember urine can be significantly more concentrated relative to urine from ground donors. As a result, gypsum precipitated in the DA when operating at water recovery rates at or near 85%, causing the failure and subsequent re14 NASA Tech Briefs, September 2013 placement of the DA. Later investigations have demonstrated that an excess of calcium and sulfate will cause precipitation at water recovery rates greater than 70%. The source of the excess calcium is likely physiological in nature, via crewmembers' bone loss, while the excess sulfate is primarily due to the sulfuric acid component of the urine pretreatment. To prevent gypsum precipitation in the UPA, the Precipitation Prevention Project (PPP) team has focused on removing the calcium ion from pretreated urine, using ion exchange resins as calcium removal agents. The selectivity and effectiveness of ion exchange resins are determined by such factors as the mobility of the liquid phase through the polymer matrix, the density of functional groups, type of functional groups bound to the matrix, and the chemical characteristics of the liquid phase (pH, oxidation potential, and ionic strength). Previous experience with ion exchange resins has demonstrated that the most effective implementation for an ion exchange resin is a cartridge, or column, in which the resin is contained. Based on the results of equilibrium and sub-scale dynamic column testing, a possible solution for mitigating the calcium precipitation issue on the ISS has been identified. From an original pool of 13 ion exchange resins, two candidates have been identified that demonstrate substantial calcium removal on the sub-scale. The dramatic reduction in resin performance from published calcium uptake demonstrates the need for thorough evaluation of resins at the low pH and strong oxidizing environment present in the UPA. Chemical variations in the influent (calcium concentrations and pretreatment dosing) appear to have a noticeable impact on the calcium capacity of the resin. Low calcium concentrations and high pretreatment dosing will likely result in a decrease in calcium capacity. Conversely, low pre trea t - ment dosing will likely result in an increase in calcium capacity. In contrast, investigations at a variety of flow rates, length-to-diameter ratios, resin volumes, and flow regimes (continuous versus pulsed) show that changes in physical parameters do not have substantial impacts on resin performance in the very low specific velocity ranges of interest. This result is particularly useful because most commercial applications at higher specific velocities do show a relatively strong relationship between flow and capacity. The lack of a strong relationship will allow more flexibility in the implementation of an ion exchange bed for flight. Verification of subscale tests with flight-scale resin beds is recommended prior to implementation in the on-orbit UPA.

Mitchell, Julie; Broyan, James; Pickering, Karen

2013-01-01

245

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

PubMed

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. PMID:20462180

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

2010-06-01

246

Lead Removal From Synthetic Leachate Matrices by a Novel Ion-Exchange Material  

NASA Technical Reports Server (NTRS)

This report discusses the application of a novel polyacrylate-based ion-exchange material (IEM) for the removal of lead (Pb) ions from water. Preliminary testing includes the establishment of the operating pH range, capacity information, and the effect of calcium and anions in the matrix. Batch testing with powder indicates slightly different optimal operational conditions from those used for column testing. The ion exchanger is excellent for removing lead from aqueous solutions.

Street, Kenneth W., Jr.; Hovanitz, Edward S.; Chi, Sulan

2002-01-01

247

Ion-exchange and hydrophobic interactions affecting selectivity for neutral and charged solutes on three structurally similar agglomerated ion-exchange and mixed-mode stationary phases.  

PubMed

The nature and extent of mixed-mode retention mechanisms evident for three structurally related, agglomerated, particle-based stationary phases were evaluated. These three agglomerated phases were Thermo Fisher ScientificIon PacAS11-HC - strong anion exchange, Thermo Fisher Scientific IonPac CS10--strong cation-exchange PS-DVB, and the Thermo Fisher Scientific Acclaim Trinity P1silica-based substrate, which is commercially marketed as a mixed-mode stationary phase. All studied phases can exhibit zwitterionic and hydrophobic properties, which contribute to the retention of charged organic analytes. A systematic approach was devised to investigate the relative ion-exchange capacities and hydrophobicities for each of the three phases, together with the effect of eluent pH upon selectivity, using a specifically selected range of anionic, cationic and neutral aromatic compounds. Investigation of the strong anion-exchange column and the Trinity P1 mixed-mode substrate, in relation to ion-exchange capacity and pH effects, demonstrated similar retention behaviour for both the anionic and ampholytic solutes, as expected from the structurally related phases. Further evaluation revealed that the ion-exchange selectivity of the mixed-mode phase exhibited properties similar to that of the strong anion-exchange column, with secondary cation-exchange selectivity, albeit with medium to high anion-exchange and cation-exchange capacities, allowing selective retention for each of the anionic, cationic and ampholytic solutes. Observed mixed-mode retention upon the examined phases was found to be a sum of anion- and cation-exchange interactions, secondary ion-exchange and hydrophobic interactions, with possible additional hydrogen bonding. Hydrophobic evaluation of the three phases revealed logP values of 0.38-0.48, suggesting low to medium hydrophobicity. These stationary phases were also benchmarked against traditional reversed-phase substrates namely, octadecylsilica YMC-Pac Pro C18 and neutral ?PS-DVB resin IonPac NS1-5u, yielding logP values of 0.57 and 0.52, respectively. PMID:24216208

Kazarian, Artaches A; Taylor, Mark R; Haddad, Paul R; Nesterenko, Pavel N; Paull, Brett

2013-11-25

248

Revised Thermal Analysis of LANL Ion Exchange Column  

SciTech Connect

This document updates a previous calculation of the temperature distributions in a Los Alamos National Laboratory (LANL) ion exchange column.1 LANL operates two laboratory-scale anion exchange columns, in series, to extract Pu-238 from nitric acid solutions. The Defense Nuclear Facilities Safety Board has requested an updated analysis to calculate maximum temperatures for higher resin loading capacities obtained with a new formulation of the Reillex HPQ anion exchange resin. The increased resin loading capacity will not exceed 118 g plutonium per L of resin bed. Calculations were requested for normal operation of the resin bed at the minimum allowable solution feed rate of 30 mL/min and after an interruption of flow at the end of the feed stage, when one of the columns is fully loaded. 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. At low temperatures, resin bed temperatures increase primarily due to decay heat. At {approx}70 C a Low Temperature Exotherm (LTE) resulting from the reaction between 8-12 M HNO{sub 3} and the resin has been observed. The LTE has been attributed to an irreversible oxidation of pendant ethyl benzene groups at the termini of the resin polymer chains by nitric acid. The ethyl benzene groups are converted to benzoic acid moities. The resin can be treated to permanently remove the LTE by heating a resin suspension in 8M HNO{sub 3} for 30-45 minutes. No degradation of the resin performance is observed after the LTE removal treatment. In fact, heating the resin in boiling ({approx}115-120 C) 12 M HNO{sub 3} for 3 hr displays thermal stability analogous to resin that has been treated to remove the LTE. The analysis is based on a previous study of the SRS Frames Waste Recovery (FWR) column, performed in support of the Pu-238 production campaign for NASA's Cassini mission. In that study, temperature transients following an interruption of flow to the column were calculated. The transient calculations were terminated after the maximum resin bed temperature reached the Technical Standard of 60 C, which was set to prevent significant resin degradation. The LANL column differs from the FWR column in that it has a significantly smaller radius, 3.73 cm nominal versus approximately 28 cm. It follows that natural convection removes heat much more effectively from the LANL column, so that the column may reach thermal equilibrium. Consequently, the calculations for a flow interruption were extended until an approach to thermal equilibrium was observed. The LANL ion exchange process also uses a different resin than was used in the FWR column. The LANL column uses Reillex HPQ{trademark} resin, which is more resistant to attack by nitric acid than the Ionac 641{trademark} resin used in the FWR column. Heat generation from the resin oxidation reaction with nitric acid is neglected in this analysis since LANL will be treating the resin to remove the LTE prior to loading the resin in the columns. Calculations were performed using a finite difference computer code, which incorporates models for absorption and elution of plutonium and for forced and natural convection within the resin bed. Calculations for normal column operation during loading were performed using an initial temperature and a feed temperature equal to the ambient air temperature. The model for the normal flow calculations did not include natural convection within the resin bed. The no flow calculations were started with the temperature and concentration profiles at the end of the loading stage, when there would be a maximum amount of plutonium either adsorbed on the resin or in the feed solution in the column.

Laurinat, J

2006-04-11

249

THERMAL MODELING OF ION EXCHANGE COLUMNS WITH SPHERICAL RF RESIN  

SciTech Connect

Models have been developed to simulate the thermal performance of RF columns fully loaded with radioactive cesium. Temperature distributions and maximum temperatures across the column were calculated during Small Column Ion Exchange (SCIX) process upset conditions with a focus on implementation at Hanford. A two-dimensional computational modeling approach was taken to include conservative, bounding estimates for key parameters such that the results will provide the maximum centerline temperatures achievable under the design configurations using a feed composition known to promote high cesium loading on RF. The current full-scale design for the SCIX system includes a central cooling tube, and one objective of these calculations was to examine its elimination to simplify the design. Results confirmed that a column design without a central cooling tube is feasible for RF, allowing for the possibility of significant design simplifications if it can be assumed that the columns are always filled with liquid. With active cooling through the four outer tubes, the maximum column diameter expected to maintain the temperature below the assumed media and safety limits is 26 inches, which is comparable to the current design diameter. Additional analysis was conducted to predict the maximum column temperatures for the previously unevaluated accident scenario involving inadvertent drainage of liquid from a cesium-saturated column, with retention of the ion exchange media and cesium in the column. As expected, much higher maximum temperatures are observed in this case due to the poor heat transfer properties of air versus liquid. For this hypothetical accident scenario involving inadvertent and complete drainage of liquid from a cesium-saturated column, the modeling results indicate that the maximum temperature within a 28 inch diameter RF column with external cooling is expected to exceed 250 C within 2 days, while the maximum temperature of a 12 inch column is maintained below 100 C. In addition, the calculation results demonstrate that the cooling tube system external to an air-filled column is not highly effective at reducing the maximum temperature, but the baseline design using a central cooling tube inside the column provides sufficient cooling to maintain the maximum temperature near the assumed safety limit.

Lee, S.; King, W.

2009-12-30

250

Fast ion charge exchange spectroscopy adapted for tangential viewing geometry in LHD  

SciTech Connect

A tangential Fast Ion Charge eXchange Spectroscopy is newly applied on a Large Helical Device (LHD) for co/countercirculating fast ions, which are produced by high energy tangential negative-ion based neutral beam injection. With this new observation geometry, both the tangential-neutral beam (NB) and a low-energy radial-NB based on positive ions can be utilized as probe beams of the measurement. We have successfully observed Doppler-shifted H-alpha lights due to the charge exchange process between the probing NB and circulating hydrogen ions of around 100 keV in LHD plasmas.

Ito, T.; Osakabe, M.; Ida, K.; Yoshinuma, M.; Kobayashi, M.; Goto, M.; Isobe, M.; Toi, K.; Takeiri, Y.; Okamura, S. [National Institute for Fusion Science, Toki 509-5292 (Japan); Murakami, S.; Kobayashi, S. [Department of Nuclear Engineering, Kyoto University, Kyoto 606-8501 (Japan); Ogawa, K. [Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8601 (Japan)

2010-10-15

251

Selectivity of ion exchangers in extracting cesium and rubidium from alkaline solutions  

NASA Astrophysics Data System (ADS)

We compare the ion exchange selectivity of phenol-type sorbents based on phenol formaldehyde resins, products of condensation of diatomic phenols with formaldehyde, and crosslinked polymer based on C-phenyl[4]resorcinarene resin, for cesium and rubidium ions. It is shown that phenol formaldehyde sorbents are the ones most selective. The interaction of alkali metal cations with the anion of calix[4]arene is investigated via quantum-chemical modeling. It is shown that the selectivity toward cesium and rubidium ions in ion exchangers of the phenolic type is not due to specific interactions of ions with phenolic groups.

Shelkovnikova, L. A.; Kargov, S. I.; Gavlina, O. T.; Ivanov, V. A.; Al'tshuler, G. N.

2013-01-01

252

Specific features of the luminescence of silicate glasses with silver introduced by ion exchange  

NASA Astrophysics Data System (ADS)

The luminescence spectra of silicate glasses with silver introduced by ion exchange have been investigated. It is shown that silver introduced into glass by ion exchange exists not only in the form of ions, but also as neutral atoms and charged and neutral molecular clusters, which provide intense luminescence in the visible spectral range. Cerium ions in glass facilitate the formation of neutral molecular silver clusters, due to which the luminescence intensity increases. It is shown that Ag n -Ce x+ complexes can be formed in glass containing cerium ions and neutral molecular silver clusters.

Demichev, I. A.; Ignat'ev, A. I.; Nikonorov, N. V.; Sgibnev, E. M.; Sidorov, A. I.; Khrushcheva, T. A.; Shakhverdov, T. A.

2014-04-01

253

Cement waste-form development for ion-exchange resins at the Rocky Flats Plant  

SciTech Connect

This report describes the development of a cement waste form to stabilize ion-exchange resins at Rocky Flats Environmental Technology Site (RFETS). These resins have an elevated potential for ignition due to inadequate wetness and contact with nitrates. The work focused on the preparation and performance evaluation of several Portland cement/resin formulations. The performance standards were chosen to address Waste Isolation Pilot Plant and Environmental Protection Agency Resource Conservation and Recovery Act requirements, compatibility with Rocky Flats equipment, and throughput efficiency. The work was performed with surrogate gel-type Dowex cation- and anion-exchange resins chosen to be representative of the resin inventory at RFETS. Work was initiated with nonactinide resins to establish formulation ranges that would meet performance standards. Results were then verified and refined with actinide-containing resins. The final recommended formulation that passed all performance standards was determined to be a cement/water/resin (C/W/R) wt % ratio of 63/27/10 at a pH of 9 to 12. The recommendations include the acceptable compositional ranges for each component of the C/W/R ratio. Also included in this report are a recommended procedure, an equipment list, and observations/suggestions for implementation at RFETS. In addition, information is included that explains why denitration of the resin is unnecessary for stabilizing its ignitability potential.

Veazey, G.W. [Los Alamos National Labs., NM (United States); Ames, R.L. [Rocky Flats Environmental Technology Site, Golden, CO (United States)

1997-03-01

254

Growth Rate of Calcite Steps as a Function of Aqueous Calcium-to-Carbonate Ratio: Independent Attachment and Detachment of Calcium and Carbonate Ions  

SciTech Connect

Growth rates of monolayer-height steps on the {1014} calcite surface have been measured as a function of the aqueous calcium-to-carbonate ratio. The maximum growth rates of the two common crystallographic orientations were found to deviate from the ideal stoichiometric ratio of 1:1, and dissolution features were observed under supersaturated solutions containing high calcium-to-carbonate ratios. To explain these phenomena, a theory is applied that treats the rates of attachment and detachment of aqueous calcium and carbonate ions separately. The resultant attachment rate constants are 1-3 orders of magnitude smaller than the water exchange rate of the constituent aqueous ions, suggesting that ligand-exchange processes may directly drive attachment. The broader implication is that the saturation state alone is not adequate to fully describe the rates of the multiple, independent reactions that occur on mineral surfaces under these conditions.

Stack, Andrew G [ORNL; Grantham, Ms. Meg [Georgia Institute of Technology

2010-01-01

255

Cementation of ILW ion exchange resins: Impact of sulfate ions released by radiolysis on hydrated matrix  

NASA Astrophysics Data System (ADS)

Some of the ion exchange resins used during treatment of spent nuclear fuels are intermediate level radioactive wastes which may be damaged by radiolysis process, releasing sulfate ions directly into the cement-based encapsulating material. This work consists in an experimental study of the resulting sulfate attack on the properties of the hydrated matrix: dimensional stability, mineralogy and microstructure of the samples, as well as variations in the chemical composition of the curing solution, were studied during six months. Three sites of delayed ettringite formation were detected: into the cement matrix near the surface exposed to solution, localized in the interfacial transition zone between cement matrix and resins, or progressively replacing the portlandite that initially fulfilled the cracks of anionic resins. During the experiment period, the ettringite precipitation and the expansion detected were moderate, and did not lead to cracking. The material involved was considered as having a good resistance to sulfate attack.

Frizon, F.; Cau-dit-Coumes, C.

2006-12-01

256

Multivariate analysis of Ion Beam Induced Luminescence spectra of irradiated silver ion-exchanged silicate glasses.  

PubMed

A multivariate analysis is used for the identification of the spectral features in Ion Beam Induced Luminescence (IBIL) spectra of soda-lime silicate glasses doped with silver by Ag(+)-Na(+) ion exchange. Both Principal Component Analysis and multivariate analysis were used to characterize time-evolving IBIL spectra of Ag-doped glasses, by means of the identification of the number and of the wavelength positions of the main luminescent features and the study of their evolution during irradiation. This method helps to identify the spectral features of the samples spectra, even when partially overlapped or less intense. This analysis procedure does not require additional input such as the number of peaks. PMID:22571943

Valotto, Gabrio; Quaranta, Alberto; Cattaruzza, Elti; Gonella, Francesco; Rampazzo, Giancarlo

2012-09-01

257

Glass ion-exchange technology for wavelength management applications  

NASA Astrophysics Data System (ADS)

We report the achievement of buried single-mode waveguides in special Boro-Aluminum-Silicate glass. The waveguides are characterized by very low propogation loss (<.01dB/cm) and negligible birefringence. The optical mode at the input and output ports is essentially identical to the mode of a standard single-mode optical fiber. We fabricated and tested several devices and report here 1×8 and 1×16 powers spitters and an interleaver defined for a 100GHz DWDM network. Due to the low birefringence of the waveguides, the TE and TM responses of the device are undistinguishable by customary characterization equipment. In addition we report a technique for permanent trimming of the otpical circuit by localized heating. This unique advantage of ion-exchange technology, allowed us the adjustment of devices' parameters at post-fabrication stage. As an example, the trimming of a 2×2 directional coupler manifested here in the control of coupling coefficient value over a wide range (0.04-1.5). The process control was such that a target value of 0.5 for the coefficient was accurately attained. The same process enabled us the tuning of the interleaver to the ITU grid within 10pm accuracy.

Ruschin, Shlomo; Hurwitz, G.; Hurwitz, T.; Kepten, Avishai; Arad, E.; Soreq, Y.; Eckhouse, Shimon

2003-04-01

258

Ion Exchange Resin and Clay Vitrification by Plasma Discharges  

NASA Astrophysics Data System (ADS)

The lack of treatment of a low and intermediate level radioactive waste (LILRW) lead us to propose a vitrification process based on a plasma discharge; this technique incorporates LILRW into a matrix glass composed of ceramic clays material. The Mexican Institute of Nuclear Research (ININ), uses an ion exchange resin IRN 150 (styrene-divinilbence copolymer) in the TRIGA MARK III nuclear reactor. The principal objective of this resin is to absorb particles containing heavy metals and low-level radioactive particles. Once the IRN 150 resin filter capacity has been exceeded, it should be replaced and treated as LILRW. In this work, a transferred plasma system was realized to vitrify this resin taking advantage of its high power density, enthalpy and chemical reactivity as well as its rapid quenching and high operation temperatures. In order to characterize the morphological structure of these clay samples, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Thermogravimetric analysis (TGA) techniques were applied before and after the plasma treatment.

Díaz A., Laura V.; Pacheco S., Joel O.; Pacheco P., Marquidia; Monroy G., Fabiola; Emeterio H., Miguel; Ramos F., Fidel

2006-12-01

259

Ultra-compact three-port trench-based photonic couplers in ion-exchanged glass waveguides  

NASA Astrophysics Data System (ADS)

An ultra-compact three-port photonic coupler is proposed on a glass substrate based upon a principle of frustrated total internal reflection. A single slash shape narrow trench at the “T” intersection of two ion-exchanged waveguides forms the coupler and is aligned 45° to the waveguides. The three-dimensional finite difference time domain (FDTD) theory is used to simulate the parameterization of the coupler, such as splitting ratios and efficiency versus trench widths, trench lengths, trench locations, and trench angles. The waveguide model used in FDTD is based on an experimental condition of the K+-Na+ ion-exchange process. A single-mode 6 ?m wide glass waveguide at 1550 nm wavelength is fabricated through the analysis of the effective index method. The numerical results show that the arbitrary splitting ratios may be controlled by trench widths and trench angles. Comparing to Si, InP and GaAs materials, trench-based coupler on glasses may readily achieve the manufacturability since the low index of glass waveguides results in a wider trench opening. Taking advantage of low loss ion-exchanged waveguides, the high efficiency and short interaction length photonic couplers have a great potential to be integrated for large scale glass-based photonic circuits.

Liu, Ke; Huang, Hui; Mu, Si Xuan; Lin, Hai; MacFarlane, Duncan L.

2013-11-01

260

Ion exhange and molecular sorption of oxalic acid with a highly basic anion exchanger  

NASA Astrophysics Data System (ADS)

Ab initio modeling of a matrix fragment of resin and geometry optimization of the molecular structure of oxalic acid were performed. The isotherm of oxalic acid sorption with AV-17-8 anion exchange resin was obtained by the variable concentrations technique. The ion-exchange and molecular components of sorbate fixation with the ion exchanger were determined. The hydration of the highly basic anion exchanger that absorbed different quantities of dicarboxylic acid was evaluated by the centrifuging method. The dependence of the amount of water and sorbate concentration in the resin was linear antibatic.

Krisilova, E. V.; Oros, G. Yu.; Krisilov, A. V.; Selemenev, V. F.

2014-04-01

261

Bifunctional phenyl monophosphonic/sulfonic acid ion exchange resin and process for using the same  

DOEpatents

A cross-linked water-insoluble ion exchange resin comprised of polymerized monomers having a phenyl ring is disclosed. A contemplated resin contains (i) polymerized phenyl ring-containing monomers having a phosphonic acid ligand linked to the phenyl ring, (ii) about 2 to about 5 millimoles per gram (mmol/g) of phosphorus as phosphonic acid ligands, and (iii) a sufficient amount of a sulfonic acid ligand such that the ratio of mmol/g of phosphonic acid to mmol/g sulfonic acid is up to 3:1. A process for removing polyvalent metal cations from aqueous solution, and a process for removing iron(III) cations from acidic copper(II) cation-containing solutions that utilize the contemplated resin or other resins are disclosed.

Alexandratos, Spiro (Knoxville, TN); Shelley, Christopher A. (Knoxville, TN); Horwitz, E. Philip (Naperville, IL); Chiarizia, Renato (Elmhurst, IL); Gula, Michael J. (Chicago, IL); Xue, Sui (Darien, IL); Harvey, James T. (Naperville, IL)

2002-01-01

262

Bifunctional phenyl monophosphonic/sulfonic acid ion exchange resin and process for using the same  

DOEpatents

A cross-linked water-insoluble ion exchange resin comprised of polymerized monomers having a phenyl ring is disclosed. A contemplated resin contains (i) polymerized phenyl ring-containing monomers having a phosphonic acid ligand linked to the phenyl ring, (ii) about 2 to about 5 millimoles per gram (mmol/g) of phosphorus as phosphonic acid ligands, and (iii) a sufficient amount of a sulfonic acid ligand such that the ratio of mmol/g of phosphonic acid to mmol/g sulfonic acid is up to 3:1. A process for removing polyvalent metal cations from aqueous solution, and a process for removing iron(III) cations from acidic copper(II) cation-containing solutions that utilize the contemplated resin or other resins are disclosed.

Alexandratos, Spiro (Knoxville, TN); Shelley, Christopher A. (Knoxville, TN); Horwitz, E. Philip (Naperville, IL); Chiarizia, Renato (Elmhurst, IL)

2001-01-01

263

Charge-exchange plasma environment for an ion drive spacecraft  

NASA Technical Reports Server (NTRS)

A model was reviewed which describes the propagation of the mercury charge-exchange plasma and extended to describe the flow of the molybdenum component of the charge-exchange plasma. The uncertainties in the models for various conditions are discussed. Such topics as current drain to the solar array, charge-exchange plasma material deposition, and the effects of space plasma on the charge-exchange plasma propagation are addressed.

Kaufman, H. R.; Carruth, M. R., Jr.

1981-01-01

264

Determination of the ratio of D + and D 2+ ions in low energy neutron generators  

NASA Astrophysics Data System (ADS)

A simple method based on the measurement of the energy-angle distribution of neutrons from the D-T reaction has been developed for the determination of the ratio of atomic and molecular ions in a bombarding deuterium beam.

Csikai, J.; Chimoye, T.; Vilaithong, T.; Chirapatpimol, N.; Singkarat, S.

1985-09-01

265

Ion Exchange and Solvent Extraction: Supramolecular Aspects of Solvent Exchange Volume 21  

SciTech Connect

Preface The theme of supramolecular chemistry (SC), entailing the organization of multiple species through noncovalent interactions, has permeated virtually all aspects of chemical endeavor over the past several decades. Given that the observed behavior of discrete molecular species depends upon their weak interactions with one another and with matrix components, one would have to conclude that SC must indeed form part of the fabric of chemistry itself. A vast literature now serves to categorize SC phenomena within a body of consistent terminology. The word supramolecular itself appears in the titles of dozens of books, several journals, and a dedicated encyclopedia. Not surprisingly, the theme of SC also permeates the field of solvent extraction (SX), inspiring the framework for this volume of Ion Exchange and Solvent Extraction. It is attempted in the six chapters of this volume to identify both how supramolecular behavior occurs and is studied in the context of SX and how SC is influencing the current direction of SX. Researchers and practitioners have long dealt with supramolecular interactions in SX. Indeed, the use of polar extractant molecules in nonpolar media virtually assures that aggregative interactions will dominate the solution behavior of SX. Analytical chemists working in the 1930s to the 1950s with simple mono- and bidentate chelating ligands as extractants noted that extraction of metal ions obeyed complicated mass-action equilibria involving complex stoichiometries. As chemists and engineers developed processes for nuclear and hydrometallurgical applications in the 1950s and 1960s, the preference for aliphatic diluents only enhanced the complexity and supramolecular nature of extraction chemistry. Use of physical techniques such as light scattering and vapor-pressure measurements together with various spectroscopic methods revealed organic-phase aggregates from well-defined dimers to small aggregates containing a few extractant molecules to large inverse micelles swollen with water molecules. Extraction systems involving long-chain cations such as alkylammonium species or long-chain anions such as sulfonates or carboxylates proved especially prone to extensive aggregate formation. The related phenomenon of third-phase formation in SX systems, long misunderstood, is now yielding to spectroscopic and scattering techniques showing extensive long-range organization. Over the last 50 years, tools for studying the structure and thermodynamics of aggregation have grown increasingly sophisticated, leading to a rich and detailed understanding of what we can now recognize as SC phenomena in SX. In the 1970s and 1980s, the rapid growth of SC elicited a paradigm shift in SX. The influence of SC principles had two major effects on the course of SX research. First, it provided a framework for understanding the supramolecular behavior that was already well appreciated in the field of SX, though earlier without the SC terminology. Second, it provided the conceptual tools to control supramolecular behavior in SX, direct it for intended functionality, and to simplify it. Extraction by designed reagents has been steadily progressing ever since, with commercial applications emerging to successfully validate this approach. With the discovery of crown ethers in the late 1960s, the advancement of extractant design has fruitfully employed the concept of inclusion. While considerable initial progress occurred with such molecules, especially because of their affinity and selectivity for alkali and alkaline earth metals, other molecular platforms such as calixarenes have proven more versatile. Multidentate receptors for partial to full inclusion of cations, anions, ion pairs, as well as neutral species, have now become commonplace for selective extraction. This volume of Ion Exchange and Solvent Extraction examines how the principles of SC are being employed both in advancing the design of new highly selective SX systems and in understanding aggregation phenomena in SX systems. Chapter 1 discusses the nature and definition of SC

Gloe, Karsten [Technischen Universität Dresden] [Technischen Universität Dresden; Tasker, Peter A [ORNL] [ORNL; Oshima, Tatsuya [University of Miyazaki] [University of Miyazaki; Watarai, Hitoshi [Institute for NanoScience Design at Osaka University] [Institute for NanoScience Design at Osaka University; Nilsson, Mikael [University of California, Irvine] [University of California, Irvine

2013-01-01

266

Cerium doped soda-lime-silicate glasses: effects of silver ion-exchange on optical properties  

NASA Astrophysics Data System (ADS)

Effects of silver ion-exchange on optical absorption (OA) and photoluminescence (PL) spectra of a cerium doped soda-lime-silicate glass at room temperature are investigated. The optical spectra are described in terms of the characteristic transitions 4f?5d originated in Ce 3+ ions placed mainly in two different sites of the glass network. As Ag + ions are introduced into the cerium doped glass, they are reduced to elementary silver (Ag 0) which are favoured by the reaction Ce 3++Ag +?Ce 4++Ag 0. Then, the number of Ce 3+ ions decrease inversely with depth from the surface contrarily to Ce 4+ ions does, and elementary silver diffuses and aggregates to form nanoparticles. As a consequence of these changes, the OA spectra of exchanged samples increase substantially in the UV range and the luminescence decreases significantly. The high sensitivity of PL together with deconvolution analysis of spectra, however, allows us to detect changes in the excitation and emission spectra from the earlier stages of ion-exchange. This indicates that during the ion-exchange we deal with fast processes (much shorter than 1 min). In fact, transmission electron microscopy observations of samples from the glass exchanged for a short time as 1 min at 325°C show the presence of a scanty number of silver nanoparticles, which confirms this point. Furthermore, with increasing the length of time of ion-exchange, PL spectra exhibit a progressive red shift indicative in part of a covalence increment in the oxygen-cerium coordinated bonding. We observe no luminescence from Ag + ions and other silver molecular species in contrast with other preliminary PL studies on silver ion-exchange in soda-lime-silicate glasses free of cerium. The effect is discussed on the basis of a supplementary increase in the number of Ce 4+ ions mainly due to the reaction Ce 3++Ag +?Ce 4++Ag 0, which prevents efficiently the luminescence of the silver centers.

Paje, S. E.; García, M. A.; Villegas, M. A.; Llopis, J.

2001-09-01

267

Charge exchange of multiply charged fluorine and lithium ions with Ne atoms  

SciTech Connect

The charge exchange of multiply charged fluorine and lithium ions with Ne atoms in a gas jet was recorded from the line spectra in the 125 - 350 A range, which arise from the radiative decay of the excited states of Li II - III and F III - VIII ions populated in the charge exchange. In the F III - VI ion spectra obtained from the plasma - gas interaction region we observed transitions from levels with an open (partly filled or completely open) 2s-shell, which may be populated in sequential events of single-electron charge exchange as well as in double- and many-electron charge exchange. Partial cross sections were calculated for the single-electron charge exchange of F VIII ions with Ne atoms. By way of Hartree - Fock energy level calculations it was possible to reveal resonances between the ground states of k-fold (k = 1 - 4) ionised donor atoms and the states of k-fold excited multiply charged fluorine ion resulting from the k-fold charge exchange of F VIII ions. These resonances may be responsible for the relatively large cross sections of double- and many-electron charge exchange (laser applications and other topics in quantum electronics)

Beigman, I L; Vishnyakov, E A; Luginin, M S; Ragozin, Evgenii N; Tolstikhina, I Yu [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2010-08-27

268

Cation immobilization in pyrolyzed simulated spent ion exchange resins  

NASA Astrophysics Data System (ADS)

Significant quantities of spent ion exchange resins that are contaminated by an assortment of radioactive elements are produced by the nuclear industry each year. The baseline technology for the conditioning of these spent resins is encapsulation in ordinary Portland cement which has various shortcomings none the least of which is the relatively low loading of resin in the cement and the poor immobilization of highly mobile elements such as cesium. The present study was conducted with cationic resin samples (Lewatit S100) loaded with Cs+, Sr2+, Co2+, Ni2+ in roughly equimolar proportions at levels at or below 30% of the total cation exchange capacity. Low temperature thermal treatment of the resins was conducted in inert (Ar), or reducing (CH4) gas atmospheres, or supercritical ethanol to convert the hydrated polymeric resin beads into carbonaceous materials that contained no water. This pyrolytic treatment resulted in at least a 50% volume reduction to give mechanically robust spherical materials. Scanning electron microscope investigations of cross-sections of the beads combined with energy dispersive analysis showed that initially all elements were uniformly distributed through the resin matrix but that at higher temperatures the distribution of Cs became inhomogeneous. Although Cs was found in the entire cross-section, a significant proportion of the Cs occurred within internal rings while a proportion migrated toward the outer surfaces to form a crustal deposit. Leaching experiments conducted in water at 25 °C showed that the divalent contaminant elements were very difficult to leach from the beads heated in inert atmospheres in the range 200-600 °C. Cumulative fractional loses of the order of 0.001 were observed for these divalent elements for temperatures below 500 °C. Regardless of the processing temperature, the cumulative fractional loss of Cs in water at 25 °C reached a plateau or steady-state within the first 24 h increasing only marginally up 120 h. For unheated beads, a steady-state was reached at a cumulative fractional Cs loss of about 0.0045 while for beads heated to 400 °C the steady-state was reached at a value of 0.1. Under comparable conditions leaching of Sr, Co and Ni were close to the detection limits. It is concluded that the fraction of the Cs inventory that was more readily leached derived mainly from Cs phases in the crustal deposit.

Luca, Vittorio; Bianchi, Hugo L.; Manzini, Alberto C.

2012-05-01

269

Salt Processing Through Ion Exchange at the Savannah River Site Selection of Exchange Media and Column Configuration - 9198  

SciTech Connect

The Department of Energy (DOE) has developed, modeled, and tested several different ion exchange media and column designs for cesium removal. One elutable resin and one non-elutable resin were considered for this salt processing application. Deployment of non-elutable Crystalline Silicotitanate and elutable Resorcinol Formaldehyde in several different column configurations were assessed in a formal Systems Engineering Evaluation (SEE). Salt solutions were selected that would allow a grouping of non-compliant tanks to be closed. Tests were run with the elutable resin to determine compatibility with the resin configuration required for an in-tank ion exchange system. Models were run to estimate the ion exchange cycles required with the two resins in several column configurations. Material balance calculations were performed to estimate the impact on the High Level Waste (HLW) system at the Savannah River Site (SRS). Conceptual process diagrams were used to support the hazard analysis. Data from the hazard analysis was used to determine the relative impact on safety. This report will discuss the technical inputs, SEE methods, results and path forward to complete the technical maturation of ion exchange.

Spires, Renee; Punch, Timothy; McCabe, Daniel

2009-02-11

270

Experimental Findings On Minor Actinide And Lanthanide Separations Using Ion Exchange  

SciTech Connect

This project seeks to determine if inorganic or hybrid inorganic ion-exchange materials can be exploited to provide effective americium and curium separations. Specifically, we seek to understand the fundamental structural and chemical factors responsible for the selectivity of the tested ion-exchange materials for actinide and lanthanide ions. During FY13, experimental work focused in the following areas: (1) investigating methods to oxidize americium in dilute nitric acid with subsequent ion-exchange performance measurements of ion exchangers with the oxidized americium and (2) synthesis, characterization and testing of ion-exchange materials. Ion-exchange materials tested included alkali titanates, alkali titanosilicates, carbon nanotubes and group(IV) metal phosphonates. Americium oxidation testing sought to determine the influence that other redox active components may have on the oxidation of Am(III). Experimental findings indicated that Pu(IV) is oxidized to Pu(VI) by peroxydisulfate, but there are no indications that the presence of plutonium affects the rate or extent of americium oxidation at the concentrations of peroxydisulfate being used. Tests also explored the influence of nitrite on the oxidation of Am(III). Given the formation of Am(V) and Am(VI) in the presence of nitrite, it appears that nitrite is not a strong deterrent to the oxidation of Am(III), but may be limiting Am(VI) by quickly reducing Am(VI) to Am(V). Interestingly, additional absorbance peaks were observed in the UV-Vis spectra at 524 and 544 nm in both nitric acid and perchloric acid solutions when the peroxydisulfate was added as a solution. These peaks have not been previously observed and do not correspond to the expected peak locations for oxidized americium in solution. Additional studies are in progress to identify these unknown peaks. Three titanosilicate ion exchangers were synthesized using a microwave-accelerated reaction system (MARS?) and determined to have high affinities for lanthanide ions in dilute nitric acid. 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. On the other hand, carbon nanotubes and nitrogen-doped carbon nanotubes exhibited low, but measureable affinities for lanthanide ions in dilute nitric acid solutions (pH 3 and 6). The MWCNT exhibited much lower affinities than the K-TSP in dilute nitric acid solutions. However, the MWCNT are much more chemically stable in concentrated nitric acid solutions and, therefore, may be candidates for ion exchange in more concentrated nitric acid solutions.

Hobbs, D. T.; Shehee, T. C.; Clearfield, A.

2013-09-17

271

Investigating the Use of Ion Exchange Resins for Processing Biodiesel Feedstocks  

E-print Network

feedstocks. Specifically, this research explored using ion exchange resins to remove free fatty acids (FFA) from soybean and waste cooking oils, catalyze transesterification of soybean oil, and catalyze in-situ conversion of dried algal biomass to biodiesel...

Jamal, Yousuf 1973-

2012-11-27

272

MODELING AN ION EXCHANGE PROCESS FOR CESIUM REMOVAL FROM ALKALINE RADIOACTIVE WASTE SOLUTIONS  

SciTech Connect

The performance of spherical Resorcinol-Formaldehyde ion-exchange resin for the removal of cesium from alkaline radioactive waste solutions has been investigated through computer modeling. Cesium adsorption isotherms were obtained by fitting experimental data using a thermodynamic framework. Results show that ion-exchange is an efficient method for cesium removal from highly alkaline radioactive waste solutions. On average, two 1300 liter columns operating in series are able to treat 690,000 liters of waste with an initial cesium concentration of 0.09 mM in 11 days achieving a decontamination factor of over 50,000. The study also tested the sensitivity of ion-exchange column performance to variations in flow rate, temperature and column dimensions. Modeling results can be used to optimize design of the ion exchange system.

Smith, F; Luther Hamm, L; Sebastian Aleman, S; Johnston Michael, J

2008-08-26

273

Ion-exchange chromatography separation applied to mineral recycle in closed systems  

NASA Technical Reports Server (NTRS)

As part of the controlled ecological life support system (CELSS) program, a study is being made of mineral separation on ion-exchange columns. The purpose of the mineral separation step is to allow minerals to be recycled from the oxidized waste products of plants, man, and animals for hydroponic food production. In the CELSS application, relatively large quantities of minerals in a broad concentration range must be recovered by the desired system, rather than the trace quantities and very low concentrations treated in analytical applications of ion-exchange chromatography. Experiments have been carried out to assess the parameters pertinent to the scale-up of ion-exchange chromatography and to determine feasibility. Preliminary conclusions are that the column scale-up is in a reasonable size range for the CELSS application. The recycling of a suitable eluent, however, remains a major challenge to the suitability of using ion exchange chromatography in closed systems.

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

1981-01-01

274

Spatial distributions of scandium in granules of different ion-exchangers  

SciTech Connect

Scanning electron microscopy (SEM) and electron probe microanalysis (EPM) using an electron probe with high local sensitivity in nondestructive action on the sample, which is important in the analysis of ion-exchange materials, are efficient methods for physicochemical studies. SEM and EPM make it possible to study the spatial distribution of elements, characteristics of their absorption by ion-exchange materials, and establish the mechanisms of physicochemical transformations, the composition of microsections of granules, etc.. Effective ion-exchangers for extraction of scandium from sulfuric acid solutions were selected, and the characteristics of sorption absorption of scandium and the accompanying elements on these ion-exchangers were investigated by SEM and EPM. 11 refs., 2 figs.

Komarova, N.I.; Molchanova, T.V.; Rodionov, V.V.; Vodolazov, L.I.

1992-01-20

275

Non-centrosymmetric behavior of a clay film ion-exchanged with chiral metal complexes.  

PubMed

SHG measurements on a highly transparent clay film ion-exchanged with chiral metal complexes revealed that the mono-molecular layer of the chiral complexes in an interlayer space acquired a non-centrosymmetric character. PMID:19904362

Suzuki, Yasutaka; Matsunaga, Ryoya; Sato, Hisako; Kogure, Toshihiro; Yamagishi, Akihiko; Kawamata, Jun

2009-12-01

276

Design, optimization, and selectivity of inorganic ion-exchangers for radioactive waste remediation  

E-print Network

studies because of their ion-exchange properties tunable by alterations of synthetic procedures, and isomorphous framework substitution. The Nb-substitution in titanium sites reduces the framework charge, whereas Ge substitution decreases the unit cell...

Medvedev, Dmitry Gennadievich

2005-11-01

277

Effect of ion exchange on strength and slow crack growth of a dental porcelain  

Microsoft Academic Search

ObjectivesTo determine the effect of ion exchange on slow crack growth (SCG) parameters (n, stress corrosion susceptibility coefficient, and ?f0, scaling parameter) and Weibull parameters (m, Weibull modulus, and ?0, characteristic strength) of a dental porcelain.

Vinicius Rosa; Humberto N. Yoshimura; Marcelo M. Pinto; Catia Fredericci; Paulo F. Cesar

2009-01-01

278

Electromechanical performance and other characteristics of IPMCs fabricated with various commercially available ion exchange membranes  

NASA Astrophysics Data System (ADS)

Ionic polymer-metal composites (IPMCs) are considered as some of the favorable candidates to be used as biomimetic actuators and sensors in an aqueous environment. Amongst all components that compose an IPMC, the ion exchange membrane is where hydrated cations migrate when an electric field is applied across the membrane and it eventually produces the deformation of the IPMC. Nafion® is the most commonly used ion exchange membrane. Many studies have been conducted on IPMCs made with Nafion®. In this study, three other commercially available ion exchange membranes were used to fabricate IPMCs and their performance as actuators was compared with IPMCs made with Nafion® membrane. Their potential for use in IPMC actuators was investigated by conducting various characterizations such as water uptake, ion exchange capacity, morphology, thermal property, blocking force and bending displacement.

Park, Jiyeon; Palmre, Viljar; Hwang, Taeseon; Kim, Kwang; Yim, Woosoon; Bae, Chulsung

2014-07-01

279

Equilibrium data for cesium ion exchange of Hanford CC and NCAW tank waste  

SciTech Connect

Hanford alkaline waste storage-tank contents will be processed to remove the soluble salts. A major fraction of these solutions will require cesium recovery to produce a low-level waste (LLW). The technology for decontamination of high-level alkaline waste and sludge wash waters is being developed. At the request of Westinghouse Hanford Company (WHC), the Pacific Northwest Laboratory (PNL) has studied several ion exchange materials for the recovery of cesium from Hanford waste tanks. The WHC program was divided into tow main tasks, (1) to obtain equilibrium data for cesium ion exchange, and (2) to evaluate ion exchange column performance. The subject of this letter report is the measurement of batch distribution coefficients for several ion exchange media for a range of operating conditions for two types of waste; complexant concentrate (CC) and neutralized current acid waste (NCAW).

Bray, L.A.; Carson, K.J.; Elovich, R.J.; Kurath, D.E.

1996-04-01

280

Adsorption of fluoride, chloride, bromide, and bromate ions on a novel ion exchanger.  

PubMed

A novel ion exchanger based on double hydrous oxide (Fe2O3Al2O3xH2O) was obtained by the original sol-gel method from easily available and cheap raw materials and employed for adsorption of F-, Cl-, Br-, and BrO-3 from simultaneous solutions. Adsorbent was characterized by potentiometric titration, zeta-potential, and poremetrical characteristics. A technologically attractive pH effect of F-, Br-, and BrO-3 sorption on the investigated double hydroxide of Fe and Al, which is capable of working in the pH range 3 to 8.5, was observed. Kinetic data on fluoride and bromide sorption fit well the pseudo-second-order model. Isotherms of fluoride, bromide, chlorine, and bromate ion sorption on Fe2O3Al2O3xH2O were obtained at pH 4. The isotherm of F- sorption fit well the Langmuir model; sorption affinity (K=0.52 L/mg) and sorption capacity (90 mg F/g) were high. In the competitive adsorption of bromide and bromate, bromide dominated at equilibrium concentrations of the ions >40 mg/L. The mechanism of fluoride adsorption to the surface of the model cluster of the sorbent synthesized and the geometry of the cluster itself were modeled with the HyperChem7 program using the PM3 method. PMID:15964584

Chubar, N I; Samanidou, V F; Kouts, V S; Gallios, G G; Kanibolotsky, V A; Strelko, V V; Zhuravlev, I Z

2005-11-01

281

Selective factor VIII and V inactivation by iminodiacetate ion exchange resin through metal ion adsorption.  

PubMed

The procoagulant activity of factors VIII and V depends on the presence of metal ion(s). We examined the effect of cation-exchange resins with different functional groups on both factors, of which only reaction with iminodiacetate resin resulted in the complete loss of their activity levels in plasma. However, the antigen level of factor VIII was preserved by >95%. This resin reduced divalent cations content present in factor VIII preparations, indicating that it inactivated this factor by direct deprivation of predominant Ca(2+) (>Mn(2+)>Cu(2+)), rather than adsorption of the factor itself. The antigen level of recombinant factor VIII alone was decreased by >95% by reaction with resin, whilst that complexed with von Willebrand factor was preserved by >95%. Iminodiacetate resin-treated plasma was evaluated by measuring factor VIII and V activity in plasma with various levels of either activity. These were significantly correlated to the values obtained using factor VIII- or V-deficient plasma prepared commercially by immunodepletion. We demonstrated that iminodiacetate resin-induced factors VIII and V inactivation is because of direct deprivation of metal ions, predominantly Ca(2+), which is more essential for the functional structure of their molecules. Furthermore, iminodiacetate resin-treated plasma would be useful as a substrate for measuring the activity of these factors. PMID:18643923

Takeyama, Masahiro; Nogami, Keiji; Okuda, Masahiro; Sakurai, Yoshihiko; Matsumoto, Tomoko; Tanaka, Ichiro; Yoshioka, Akira; Shima, Midori

2008-09-01

282

An age-dependent alteration of the respiratory exchange ratio in the db/db mouse  

PubMed Central

The leptin receptor-deficient db/db mouse is a rodent model of type 2 diabetes and obesity. Diabetes in db/db mice shows an age-dependent progression, with early insulin resistance followed by an insulin secretory defect resulting in profound hyperglycemia. However, there is insufficient data on agedependent changes of energy metabolism in db/db mice. We demonstrated an age-dependent decrease in the respiratory exchange ratio (RER), calculated by a ratio of VO2/VCO2, in db/db mice. The RER determined by indirect calorimetry, was 1.03 in db/db mice under 6 weeks of age, which were similar to those in heterozygote (db/+) and wild-type (+/+) mice. However, RER decreased from approximately 0.9 to 0.8 by 10 weeks of age and subsequently returned to approximately 0.9 at 22 weeks of age. The changes in RER were concurrent with the alterations in body weight and blood glucose level. However, other metabolic indicators such as glucose tolerance, changes in body fat mass, and urinary glucose levels, did not change with age. The results suggested that the energy source utilized in db/db mice changed with the age-related progression of diabetes. PMID:25806077

Choi, Hye-Min; Kim, Hae Rim; Kim, Eun-Kyoung; Byun, Yong Sub; Won, Young-Suk; Yoon, Won-Ki; Kim, Hyoung-Chin; Kang, Jong-Goo

2015-01-01

283

Experimental Ion Exchange Column With SuperLig 639 And Simulant Formulation  

SciTech Connect

SuperLig®639 ion exchange resin was tested as a retrieval mechanism for pertechnetate, through decontamination of a perrhenate spiked 5M Simple Average Na{sup +} Mass Based Simulant. Testing included batch contacts and a three-column ion exchange campaign. A decontamination of perrhenate exceeding 99% from the liquid feed was demonstrated. Analysis of the first formulation of a SBS/WESP simulant found unexpectedly low concentrations of soluble aluminum. Follow-on work will complete the formulation.

Morse, Megan; Nash, C.

2013-08-26

284

A kinetic model for ion exchange between cesium and sodium using silico-titanates  

E-print Network

A KINETIC MODEL FOR ION EXCHANGE BETWEEN CESIUM AND SODIUM USING SILICO-TITANATES A Thesis by LUAN THANH NGUYEN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... Kinetic Model for Ion Exchange Between Cesium and Sodium Using Silico-Titanates. (December 1994) Luan Thanh Nguyen, B. S. in Chemical Engineering, University of Houston; M. S, in Applied Mathematics, University of Houston Chair of Advisory Committee...

Nguyen, Luan Thanh

1994-01-01

285

Assessment of commercially available ion exchange materials for cesium removal from highly alkaline wastes  

SciTech Connect

Approximately 61 million gallons of nuclear waste generated in plutonium production, radionuclide removal campaigns, and research and development activities is stored on the Department of Energy`s Hanford Site, near Richland, Washington. Although the pretreatment process and disposal requirements are still being defined, most pretreatment scenarios include removal of cesium from the aqueous streams. In many cases, after cesium is removed, the dissolved salt cakes and supernates can be disposed of as LLW. Ion exchange has been a leading candidate for this separation. Ion exchange systems have the advantage of simplicity of equipment and operation and provide many theoretical stages in a small space. The organic ion exchange material Duolite{trademark} CS-100 has been selected as the baseline exchanger for conceptual design of the Initial Pretreatment Module (IPM). Use of CS-100 was chosen because it is considered a conservative, technologically feasible approach. During FY 96, final resin down-selection will occur for IPM Title 1 design. Alternate ion exchange materials for cesium exchange will be considered at that time. The purpose of this report is to conduct a search for commercially available ion exchange materials which could potentially replace CS-100. This report will provide where possible a comparison of these resin in their ability to remove low concentrations of cesium from highly alkaline solutions. Materials which show promise can be studied further, while less encouraging resins can be eliminated from consideration.

Brooks, K.P.; Kim, A.Y.; Kurath, D.E.

1996-04-01

286

OPERATING A SMALL FULL-SCALE ION EXCHANGE SYSTEM FOR URANIUM REMOVAL (JOURNAL VERSION)  

EPA Science Inventory

The design and operation of a small full-scale ion exchange system used to remove uranium from well water in the foothills west of Denver, Colorado, are described. Consistent removal of uranium was accomplished by anion exchange treatment at a reasonable cost. Because of a lack o...

287

Effects of Ion-Exchange Treatment on Bromate Formation and Oxidation Efficiency during Ozonation  

E-print Network

water treatment. In this study, we applied several different ion exchangers (i.e., anion exchange resins technologies in advanced drinking water treatment processes along with activated carbon treatment. Ozonation), chlorine-resistant pathogenic organisms, and various micropollutants in drinking water treatment. In Japan

Takada, Shoji

288

Comparison between different ion exchange resins for the deacidification of passion fruit juice  

Microsoft Academic Search

Passion fruit is highly appreciated for its aroma, but its strong acidity limits its use in formulated food products. In this study, deacidification of clarified passion fruit juice using ion exchange resins has been evaluated. Ten commercial weakly basic anion exchange resins were compared using a 50 ml column. The deacidification was carried out in order to increase juice pH

Edwin Vera; Manuel Dornier; Jenny Ruales; Fabrice Vaillant; Max Reynes

2003-01-01

289

21 CFR 173.25 - Ion-exchange resins.  

Code of Federal Regulations, 2012 CFR

...dimethylamine and oxidized with hydrogen peroxide whereby the resin contains not...calcium, carbonate, chloride, hydrogen, hydroxyl, magnesium...cation-exchange resins in the hydrogen form identified in...

2012-04-01

290

21 CFR 173.25 - Ion-exchange resins.  

Code of Federal Regulations, 2013 CFR

...dimethylamine and oxidized with hydrogen peroxide whereby the resin contains not...calcium, carbonate, chloride, hydrogen, hydroxyl, magnesium...cation-exchange resins in the hydrogen form identified in...

2013-04-01

291

21 CFR 173.25 - Ion-exchange resins.  

Code of Federal Regulations, 2011 CFR

...dimethylamine and oxidized with hydrogen peroxide whereby the resin contains not...calcium, carbonate, chloride, hydrogen, hydroxyl, magnesium...cation-exchange resins in the hydrogen form identified in...

2011-04-01

292

21 CFR 173.25 - Ion-exchange resins.  

Code of Federal Regulations, 2014 CFR

...dimethylamine and oxidized with hydrogen peroxide whereby the resin contains not...calcium, carbonate, chloride, hydrogen, hydroxyl, magnesium...cation-exchange resins in the hydrogen form identified in...

2014-04-01

293

Calorimetric determination of H + \\/M + (M = Li, Cs) ion exchange in ? -titanium hydrogen phosphate  

Microsoft Academic Search

H+\\/M+ (M = Li, Cs) ion exchange in?-titanium phosphate (?-TIP) at 25°C and under static conditions has been studied. Titration and hydrolysis curves and the exchange isotherms were determined. The substitution was followed by X-ray diffraction. Direct calorimetric measurements were carried out at different degrees of conversion and the variation of the exchange enthalpy was obtained. The shape of the

Eliana González; Camino Trobajo; Ricardo Llavona; José R. García; Julio Rodríguez

1989-01-01

294

Use of ion-exchange resins in the manufacture of pharmaceutical chemical preparations  

Microsoft Academic Search

Sulfaguanidine is ionized in aqueous media by adding a proton (pK a 2.3 + 0.04). Consequently its absorption by ion exchange is possible from aqueous solutions onto strong acid cation exchangers. Experiments have been carried out under dynamic conditions. We used the interaction of sulfaguanidine solutions with the sulfonic cation exchanger KU-2. The equilibrium state was determined from an expression

G. N. Al'tshuler; E. A. Savel'ev; N. A. Shubovich

1970-01-01

295

Equilibrium Model for Ion Exchange Between Multivalent Cations and Zeolite-A in a Molten Salt  

SciTech Connect

A two-site equilibrium model that previously only accommodated monovalent cations has been extended to include divalent and trivalent cations for ion exchange between zeolite-A and molten chloride salts, a process being considered for concentrating nuclear fission products into high level waste forms. Equilibrium constants were determined by fitting the model to equilibrium data sets for ion exchange between zeolite-A and Cs ternary salt (CsCl-LiCl-KCl), Rb ternary salt (RbCl-LiCl-KCl), Na ternary salt (NaCl-LiCl-KCl), Sr ternary salt (SrCl2-LiCl-KCl), and U ternary salt (UCl3-LiCl-KCl). The results reveal a good fit between the experimental data sets and the model. The two ion exchange sites, framework sites and occluded sites, demonstrate different relative selectivities for the cations. It was found that Sr2_ is the preferred cation in the ion exchange site, and Cs_ is the preferred cation in the occlusion site. Meanwhile, Li_ has the highest combined selectivity when both ion exchange and occlusion sites are considered. Interestingly, divalent and trivalent species are more preferred in the ion exchange site than the monovalent species with the exception of Li_.

Supathorn Phongikaroon; Michael Simpson

2005-10-01

296

Photosensitivity of ion-exchanged Er-doped phosphate glass using 248nm excimer laser radiation  

NASA Astrophysics Data System (ADS)

The photosensitivity to 248nm excimer laser radiation of Er-doped Schott IOG-1 phosphate glass is presented. The photosensitive mechanism is investigated by employing a grating recording process. Index changes of up to ~2.0x10-3 were measured in silver ion-exchanged samples using diffraction efficiency measurements; whereas changes of only ~10-5 were measured for non-ion-exchanged samples. Absorption measurements allowed the identification of specific color center bands, which were attributed to the glass matrix and to the silver ions. Investigation of the exposed ion-exchanged glass using scanning electron microscopy and energy dispersive x-ray microanalysis revealed that in addition to the color centers formed, silver ion migration and ionization contribute significantly to the UV-induced index changes

Pissadakis, Stavros; Ikiades, Aris; Hua, Ping; Sheridan, Anna K.; Wilkinson, James S.

2004-07-01

297

Charge-to-mass-ratio-dependent ion heating during magnetic reconnection in the MST RFPa)  

NASA Astrophysics Data System (ADS)

Temperature evolution during magnetic reconnection has been spectroscopically measured for various ion species in a toroidal magnetized plasma. Measurements are made predominantly in the direction parallel to the equilibrium magnetic field. It is found that the increase in parallel ion temperature during magnetic reconnection events increases with the charge-to-mass ratio of the ion species. This trend can be understood if the heating mechanism is anisotropic, favoring heating in the perpendicular degree of freedom, with collisional relaxation of multiple ion species. The charge-to-mass ratio trend for the parallel temperature derives from collisional isotropization. This result emphasizes that collisional isotropization and energy transfer must be carefully modeled when analyzing ion heating measurements and comparing to theoretical predictions.

Kumar, S. T. A.; Almagri, A. F.; Craig, D.; Den Hartog, D. J.; Nornberg, M. D.; Sarff, J. S.; Terry, P. W.

2013-05-01

298

Charge-to-mass-ratio-dependent ion heating during magnetic reconnection in the MST RFP  

SciTech Connect

Temperature evolution during magnetic reconnection has been spectroscopically measured for various ion species in a toroidal magnetized plasma. Measurements are made predominantly in the direction parallel to the equilibrium magnetic field. It is found that the increase in parallel ion temperature during magnetic reconnection events increases with the charge-to-mass ratio of the ion species. This trend can be understood if the heating mechanism is anisotropic, favoring heating in the perpendicular degree of freedom, with collisional relaxation of multiple ion species. The charge-to-mass ratio trend for the parallel temperature derives from collisional isotropization. This result emphasizes that collisional isotropization and energy transfer must be carefully modeled when analyzing ion heating measurements and comparing to theoretical predictions.

Kumar, S. T. A.; Almagri, A. F.; Den Hartog, D. J.; Nornberg, M. D.; Sarff, J. S.; Terry, P. W. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States) [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Craig, D. [Wheaton College, Wheaton, Illinois 60187 (United States)] [Wheaton College, Wheaton, Illinois 60187 (United States)

2013-05-15

299

Observation and implications of high mass-to-charge ratio ions from electrospray ionization mass spectrometry.  

PubMed

High mass-to-charge ratio ions (> 4000) from electrospray ionization (ESI) have been observed for several proteins, including bovine cytochrome c (M r 12,231) and porcine pepsin (M r 34,584), by using a quadrupole mass spectrometer with an m/z 45,000 range. The ESI mass spectrum for cytochrome c in an aqueous solution gives a charge state distribution that ranges from 12 + to 2 +, with a broad, low-intensity peak in the mass-to-charge ratio region corresponding to the [M + H](+) ion. the negative ion ESI mass spectrum for pepsin in 1% acetic acid solution shows a charge state distribution ranging from 7- to 2-. To observe the [M - H](-) ion, harsher desolvation and interface conditions were required. Also observed was the abundant aggregation of the protens with average charge states substantially lower than observed for their monomeric counterparts. The negative ion ESI mass spectrum for cytochrome c in 1-100 mM NH4OAc solutions showed greater relative abundances for the higher mass-to-charge ratio ions than in acuidic solutions, with an [M - H](-) ion relative abundance approximately 50% that of the most abundant charge state peak. The observation that protein aggregates are formed with charge states comparable to monomeric species (at fower mass-to-charge ratios) suggests that the high mass-to-charge ratio monomers may be formed by the dissociation of aggregate species. The observation of low charge state and aggregate molecular ions concurrently with highly charged species may serve to support a variation of the charged residue model, originally described by Dole and co-workers (Dole, M., et al. J. Chem. Phys. 1968, 49, 2240; Mack, L. L., et al. J. Chem. Phys. 1970, 52, 4977) which involves the Coulombically driven formation of either very highly solvated molecular ions or lower ananometer-diameter droplets. PMID:24227640

Winger, B E; Light-Wahl, K J; Ogorzalek Loo, R R; Udseth, H R; Smith, R D

1993-07-01

300

Combining ion mobility spectrometry with hydrogen-deuterium exchange and top-down MS for peptide ion structure analysis.  

PubMed

The gas-phase conformations of electrosprayed ions of the model peptide KKDDDDIIKIIK have been examined by ion mobility spectrometry (IMS) and hydrogen deuterium exchange (HDX)-tandem mass spectrometry (MS/MS) techniques. [M+4H](4+) ions exhibit two conformers with collision cross sections of 418 Å(2) and 471 Å(2). [M+3H](3+) ions exhibit a predominant conformer with a collision cross section of 340 Å(2) as well as an unresolved conformer (shoulder) with a collision cross section of ~367 Å(2). Maximum HDX levels for the more compact [M+4H](4+) ions and the compact and partially-folded [M+3H](3+) ions are ~12.9, ~15.5, and ~14.9, respectively. Ion structures obtained from molecular dynamics simulations (MDS) suggest that this ordering of HDX level results from increased charge-site/exchange-site density for the more compact ions of lower charge. Additionally, a new model that includes two distance calculations (charge site to carbonyl group and carbonyl group to exchange site) for the computer-generated structures is shown to better correlate to the experimentally determined per-residue deuterium uptake. Future comparisons of IMS-HDX-MS data with structures obtained from MDS are discussed with respect to novel experiments that will reveal the HDX rates of individual residues. PMID:25267084

Khakinejad, Mahdiar; Kondalaji, Samaneh Ghassabi; Maleki, Hossein; Arndt, James R; Donohoe, Gregory C; Valentine, Stephen J

2014-12-01

301

Neutral atomic oxygen beam produced by ion charge exchange for Low Earth Orbital (LEO) simulation  

NASA Technical Reports Server (NTRS)

A low energy neutral atomic oxygen beam system was designed and is currently being assembled at the Lewis Research Center. The system utilizes a 15 cm diameter Kaufman ion source to produce positive oxygen ions which are charge exchange neutralized to produce low energy (variable from 5 to 150 eV) oxygen atoms at a flux simulating real time low Earth orbital conditions. An electromagnet is used to direct only the singly charged oxygen ions from the ion source into the charge exchange cell. A retarding potential grid is used to slow down the oxygen ions to desired energies prior to their charge exchange. Cryogenically cooled diatomic oxygen gas in the charge exchange cell is then used to transfer charge to the oxygen ions to produce a neutral atomic oxygen beam. Remaining non-charge exchanged oxygen ions are then swept from the beam by electromagnetic or electrostatic deflection depending upon the desired experiment configuration. The resulting neutral oxygen beam of 5 to 10 cm in diameter impinges upon target materials within a sample holder fixture that can also provide for simultaneous heating and UV exposure during the atomic oxygen bombardment.

Banks, Bruce; Rutledge, Sharon; Brdar, Marko; Olen, Carl; Stidham, Curt

1987-01-01

302

A simplified ion exchange bead-based KOH electrodialytic generator for capillary ion chromatography.  

PubMed

A simple potassium hydroxide electrodialytic generator (EDG) with singe membrane configuration is described. In this setup, one cation exchange resin (CER) bead is used to fabricate the EDG in place of the common membrane sheet. The device is implemented simply in a commercial stainless steel (SS) Tee which serves as both the EDG cartridge and the cathodic electrode. The present EDG has much lower internal volume (approximately 0.16(L), which is well suited with capillary ion chromatography system. The device has been tested up pressures to 3200 psi and could be directly deployed on the high-pressure side of the pump. The electrolysis gas can be effectively removed by a segment of PTFE tubing. In the tested range of 0-100mM, the KOH concentration is generated linearly with the applied current being near-Faradaic efficiency. The device permits both isocratic and gradient operation with good reproducibility, as demonstrated by the analysis of anions. PMID:19376345

Yang, Bingcheng; Zhang, Feifang; Liang, Xinmiao

2009-06-30

303

Ion-exchange material and method of storing radioactive wastes  

DOEpatents

A new cation exchanger is a modified tobermorite containing aluminum isomorphously substituted for silicon and containing sodium or potassium. The exchanger is selective for lead, rubidium, cobalt, and cadmium and is selective for cesium over calcium or sodium. The tobermorites are compatible with cement and are useful for the long-term fixation and storage of radioactive nuclear wastes.

Komarneni, S.; Roy, D.M.

1983-10-31

304

Simultaneous hydrogen and heavier element isotopic ratio images with a scanning submicron ion probe and mass resolved polyatomic ions.  

PubMed

In situ microanalysis of solid samples is often performed using secondary ion mass spectrometry (SIMS) with a submicron ion probe. The destructive nature of the method makes it mandatory to prevent information loss by using instruments combining efficient collection of secondary ions and a mass spectrometer with parallel detection capabilities. The NanoSIMS meets those requirements with a magnetic spectrometer but its mass selectivity has to be improved for accessing opportunities expected from polyatomic secondary ions. We show here that it is possible to perform D/H ratio measurement images using 12CD-/12CH-, 16OD-/16OH-, or 12C2D-/12C2H- ratios. These polyatomic species allow simultaneous recording of D/H ratios and isotopic compositions of heavier elements like 15N/14N (via 12C15N-/12C14N-) and they provide a powerful tool to select the phase of interest (e.g., mineral versus organics). We present high mass resolution spectra and an example of isotopic imaging where D/H ratios were obtained via the 12C2D-/12C2H- ratio with 12C2D- free from neighboring mass interferences. Using an advanced mass resolution protocol, a "conventional" mass resolving power of 25,000 can be achieved. Those results open many perspectives for isotopic imaging at a fine scale in biology, material science, geochemistry, and cosmochemistry. PMID:24548344

Slodzian, Georges; Wu, Ting-Di; Bardin, Noémie; Duprat, Jean; Engrand, Cécile; Guerquin-Kern, Jean-Luc

2014-04-01

305

Charge-Exchange Experiments with Highly Charged Ions and Their Relevance to Astrophysics  

NASA Astrophysics Data System (ADS)

The wide range of highly-charged ions (HCIs) and charge states produced in the electron cyclotron resonance ion source allows one to study fundamental atomic-physics processes both for their intrinsic value, and for their importance to understanding astrophysical phenomena. These phenomena include ionization fractions of solar/stellar plasmas; charge exchange with comets, circumstellar clouds, and planetary & satellite exospheres. Presented will be recent experimental and theoretical results for absolute single and multiple charge-exchange cross sections for HCI-neutral collisions, together with spectra of X-ray emissions following the charge-exchange collision. In collaboration with Stojan Madzunkov, John MacAskill, Ara Chutjian, Jet Propulsion Lab.

Simcic, Jurij

2011-06-01

306

Donnan dialysis of transition metal ions using anion exchange membrane modified with Xylenol Orange  

SciTech Connect

A chelating ion-exchange membrane was obtained by modification of a PTFE-based anion-exchange membrane with Xylenol Orange. Its utility for dialysis of Cu(II), Ni(II), Mn(II), and Zn(II) was investigated by using receiver solutions without and with iminodiacetate. 1,2-diaminocyclohexanetetraacetic acid, and tetraethylenepentamine. In comparison to commercial PTFE cation-exchange membranes, modified chelating membranes exhibit for the metal ions investigated a larger differentiation of retention in the membrane phase and transport-to-receiver solution depending on the modifier used and the composition of the receiver solution.

Sawicka, B.; Brajter, K.; Trojanowicz, M.; Kado, B. (Univ. of Warsaw (Poland))

1991-01-01

307

Quantifying exchange coupling in f-ion pairs using the diamagnetic substitution method  

SciTech Connect

One of the challenges in the chemistry of actinide and lanthanide (f-ion) is quantifying exchange coupling between f-ions. While qualitative information about exchange coupling may be readily obtained using the diamagnetic substitution approach, obtaining quantitative information is much more difficult. This article describes how exchange coupling may be quantified using the susceptibility of a magnetically isolated analog, as in the diamagnetic substitution approach, along with the anisotropy of the ground state as determined by EPR spectroscopy. Several examples are used to illustrate and test this approach.

Lukens, Wayne W.; Walter, Marc D.

2010-04-01

308

CHARACTERIZATION OF CYCLED SPHERICAL RESORCINOL-FORMALDEHYDE ION EXCHANGE RESIN  

SciTech Connect

This report presents characterization data for two spherical resorcinol-formaldehyde (sRF) resin beds that had processed cesium in non-radioactive and radioactive cycles. All column cycle operations for the resin beds including loading, displacements, elution, regeneration, breakthroughs, and solution analyses are reported in Nash and Duignan, 2009a. That report covered four ion exchange (IX) campaigns using the two {approx}11 mL beds in columns in a lead-lag arrangement. The first two campaigns used Savannah River Site (SRS) Tank 2F nonradioactive simulant while the latter two were fed with actual dissolved salt in the Savannah River National Laboratory (SRNL) Shielded Cells. Both radioactive cycles ran to cesium breakthrough of the lead column. The resin beds saw in excess of 400 bed volumes of feed in each cycle. Resin disposal plans in tank farm processing depend on characterizations of resin used with actual tank feed. Following a final 30 bed volume (BV) elution with nitric acid, the resin beds were found to contain detectable chromium, barium, boron, aluminum, iron, sodium, sulfur, plutonium, cesium, and mercury. Resin affinity for plutonium is important in criticality safety considerations. Cesium-137 was found to be less than 10E+7 dpm/g of resin, similar to past work with sRF resin. Sulfur levels are reasonably consistent with other work and are expected to represent sulfur chemistry used in the resin manufacture. There were low but detectable levels of technetium, americium, and curium. Toxicity Characteristic Leaching Procedure (TCLP) work on the used (eluted) resin samples showed significant contents of mercury, barium, and chromium. One resin sample exceeded the TCLP level for mercury while the other metals were below TCLP levels. TCLP organics measurements indicated measurable benzene in one case, though the source was unknown. Results of this work were compared with other work on similar sRF resin characterizations in this report. This is the first work to quantify mercury on sRF resin. Resin mercury content is important in plans for the disposition of used sRF resin. Mercury speciation in high level waste (HLW) is unknown. It may be partly organic, one example being methyl mercury cation. Further study of the resin's affinity for mercury is recommended.

Nash, C.; Duignan, M.

2010-02-23

309

ROTARY FILTER FINES TESTING FOR SMALL COLUMN ION EXCHANGE  

SciTech Connect

SRNL was requested to quantify the amount of 'fines passage' through the 0.5 micron membranes currently used for the rotary microfilter (RMF). Testing was also completed to determine if there is any additional benefit to utilizing a 0.1 micron filter to reduce the amount of fines that could pass through the filter. Quantifying of the amount of fines that passed through the two sets of membranes that were tested was accomplished by analyzing the filtrate by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) for titanium. Even with preparations to isolate the titanium, all samples returned results of less than the instrument's detection limit of 0.184 mg/L. Test results show that the 0.5 micron filters produced a significantly higher flux while showing a negligible difference in filtrate clarity measured by turbidity. The first targeted deployment of the RMF is with the Small Column Ion Exchange (SCIX) at the Savannah River Site (SRS). SCIX uses crystalline silicotitanate (CST) to sorb cesium to decontaminate a clarified salt solution. The passage of fine particles through the filter membranes in sufficient quantities has the potential to impact the downstream facilities. To determine the amount of fines passage, a contract was established with SpinTek Filtration to operate a 3-disk pilot scale unit with prototypic filter disk and various feeds and two different filter disk membranes. SpinTek evaluated a set of the baseline 0.5 micron filter disks as well as a set of 0.1 micron filter disks to determine the amount of fine particles that would pass the membrane and to determine the flux each set produced. The membrane on both disk sets is manufactured by the Pall Corporation (PMM 050). Each set of disks was run with three feed combinations: prototypically ground CST, CST plus monosodium titanate (MST), and CST, MST, plus Sludge Batch 6 (SB6) simulant. Throughout the testing, samples of the filtrate were collected, measured for turbidity, and sent back to SRNL for analysis to quantify the amount of fines that passed through the membrane. It should be noted that even though ground CST was tested, it will be transferred to the Defense Waste Processing Facility (DWPF) feed tank and is not expected to require filtration.

Herman, D.

2011-08-03

310

Ion exchange selectivity for cross-linked polyacrylic acid  

NASA Technical Reports Server (NTRS)

The ion separation factors for 21 common metal ions with cross-linked polyacrylic acid were determined as a function of pH and the percent of the cross-linked polyacrylic acid neutralized. The calcium ion was used as a reference. At a pH of 5 the decreasing order of affinity of the ions for the cross-linked polyacrylic acid was found to be: Hg++, Fe+++, Pb++, Cr+++, Cu++, Cd++, Al+++, Ag+, Zn++, Ni++, Mn++, Co++, Ca++, Sr++, Ba++, Mg++, K+, Rb+, Cs+, Na+, and Li+. Members of a chemical family exhibited similar selectivities. The Hg++ ion appeared to be about a million times more strongly bound than the alkali metal ions. The relative binding of most of the metal ions varied with pH; the very tightly and very weakly bound ions showed the largest variations with pH. The calcium ion-hydrogen ion equilibrium was perturbed very little by the presence of the other ions. The separation factors and selectivity coefficients are discussed in terms of equilibrium and thermodynamic significance.

May, C. E.; Philipp, W. H.

1983-01-01

311

Comparison of the ion-exchange behaviour of zirconium, thorium, vanadium, uranium, stannic and titanium tungstates.  

PubMed

Zirconium, thorium, uranium, vanadium, stannic and titanium tungstates have been prepared and their properties such as ion-exchange capacity, K(d) values of metal ions, chemical composition and stability have been compared. Titanium tungstate was found to be the most stable, and to have negligible capacity for tervalent cations. PMID:18961426

Qureshi, M; Gupta, J P; Sharma, V

1974-01-01

312

Ion Exchange Protein purification products All you need for rapid protein purification in one convenient kit  

E-print Network

Removal of bacterial DNA from proteins DNA Removal Kit D Maxi M e.g. from E.coli cell lysates #12;The, reproducable and scalable protein purification. The Vivapure advantage · Fast · Cost effective · Centrifuge chemistries (e.g: range of strong or weak ion exchanges, metal chelate, Protein A, epoxy). Vivapure ion

Lebendiker, Mario

313

EVALUATION OF ION EXCHANGE MEMBRANES FOR USE IN THE FLUREX PROCESS  

Microsoft Academic Search

In the Flurex process, uranium (IV) fluoride salts are prepared from an ; aqueous uranyl nitrate feed. A threecompartment electrolytic cell consisting of ; anode, feed, and cathode compartments separately by anion and cation exchange ; membranes, respectively, is used. Nitrate ion from the uranyl nitrate feed ; migrates to the anolyte; urauyl ion migrates to the catholyte where it

E. W. Neuvar; W. W. Schulz

1958-01-01

314

Ion-exchange behavior of a number of elements on a phosphonic acid cation exchanger in hydrochloric acid solutions  

SciTech Connect

The distribution coefficients of 23 elements between the macroporous phosphonic acid cation exchanger KRF-20t-60 and hydrochloric acid solutions with concentrations ranging from 0.1-2.0 M have been determined by a static method. The KRF-20t-60 cation exchanger has a high affinity toward Fe(III), Sc(III), and Ti(IV) ions. A discussion of the results obtained and the possibilities of their use for the separation of various elements has been carried out. An example of the removal of trace amounts of beryllium from macroscopic quantities of lithium has been presented.

Razbash, A.A.; Bykhovskii, D.N.; Sevast'yanov, Yu.G.

1987-11-01

315

An assessment of inorganic ion-exchange materials for the removal of strontium from simulated Hanford tank wastes  

SciTech Connect

Several inorganic ion-exchange materials were evaluated for the removal of strontium from two simulated Hanford tank wastes (NCAW and 101SY-Cs5) using static batch experiments. Sodium titanium silicate, Na{sub 2}Ti{sub 2}O{sub 3}SiO{sub 4} {center_dot} 2H{sub 2}O (NaTS), was the best material in NCAW with a K{sub d} of 2.7 x 10{sup 5} mL/g at a volume-to-mass ratio of 200:1. In the 101SY-Cs5 simulant, strontium extraction was more difficult due to the presence of complexants and consequently K{sub d}s were greatly reduced. Sodium nonatitanate, NaTi, performed best in the presence of these complexants and gave a K{sub d} of 295 mL/g, though none of the materials performed particularly well. Pellets suitable for column studies were synthesized and the ion exchangers evaluated in column studies. Breakthrough curves correlated well with the K{sub d}s obtained from batch experiments with the sodium titanium silicate performing best in NCAW and a pelletized form of sodium nonatitanate performing best in 101SY-Cs5. Both the sodium titanate and the sodium titanosilicate performed better than IONSIV IE-911, a commercially available ion exchanger, in the NCAW simulant, and consequently could be used for the removal of {sup 90}Sr from highly alkaline tank wastes.

Sylvester, P.; Behrens, E.A.; Graziano, G.M.; Clearfield, A. [Texas A and M Univ., College Station, TX (United States). Dept. of Chemistry] [Texas A and M Univ., College Station, TX (United States). Dept. of Chemistry

1999-07-01

316

Desalination by electrodialysis with the ion-exchange membrane prepared by radiation-induced graft polymerization  

NASA Astrophysics Data System (ADS)

Ion-exchange membranes modified with the triethylamine [-N(CH 2CH 3) 3] and phosphoric acid (-PO 3 H) groups were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto the polyolefin nonwavon fabric (PNF) and subsequent chemical modification of poly(GMA) graft chains. The physical and chemical properties of the GMA-grafted PNF and the PNF modified with ion-exchange groups were investigated by SEM, XPS, TGA, and DSC. Furthermore, electrochemical properties such as specific electric resistance, transport number of K +, and desalination were examined. The grafting yield increased with increasing reaction time and reaction temperature. The maximum grafting yield was obtained with 40% (vol.%) monomer concentration in dioxane at 60°C. The content of the cation- and anion-exchange group increased with increasing grafting yield. Electrical resistance of the PNF modified with TEA and -PO 3 H group decreased, while the water uptake (%) increased with increasing ion-exchange group capacities. Transport number of the PNF modified with ion-exchange group were the range of ca. 0.82-0.92. The graft-type ion-exchange membranes prepared by radiation-induced graft copolymerization were successfully applied as separators for electrodialysis.

Choi, Seong-Ho; Han Jeong, Young; Jeong Ryoo, Jae; Lee, Kwang-Pill

2001-01-01

317

Preparation and emanation properties of an ion-exchanged solid thoron source.  

PubMed

For the calibration purpose of thoron ((220)Rn) measurements, solid sources with constant (220)Rn emanation are generally desired. In this study, Th(4+) in the thorium nitrate powder was successfully exchanged to the surfaces of sodium benzenesulphonate resins with a bead diameter of ?0.5 mm by using the ion-exchange method. Tests of (220)Rn emanating from the ion-exchanged resin indicated that the emanation rates were nearly constant, provided both the air humidity and air temperature were controlled. As the resin can be easily prepared to be of various sizes and activities of sources, the ion-exchanged resin is considered as a promising standard source for calibrations of (220)Rn measurements. PMID:22908351

Tang, F; Zhuo, W; He, L; Zhao, C; Xu, Y

2012-11-01

318

Development of a transparent, non-cytotoxic, silver ion-exchanged glass with antimicrobial activity and low ion elution.  

PubMed

We investigated the antimicrobial, cytotoxicity, skin irritation, and ion elution behaviors of glass doped with silver ions with respect to its application to electronic equipment such as phones and tablet screens. The microbes tested were Escherichia coli, Staphylococcus aureus, and Penicillium funiculosum. AgNO3 powder was spread on both sides of aluminosilicate glass, and it was heated to 250-280°C for 10min. Under optimized heating conditions (260°C, 10min), the antimicrobial activity of ion-exchanged glass against bacteria and fungi was over 99.9% after 24 weeks. The glass failed to irritate the skin of experimental animals and was considered non-cytotoxic. The maximum amount of Ag ions that were eluted from the ion-exchanged glass into drinking water was measured at 0.037±0.003?gL(-1), an amount which is several orders of magnitude below the standard limit of 0.1mgL(-1) in drinking water. Ag ion-exchanged glass had characteristics suitable for use as a display screen, such as a light transmittance of 90% and a surface roughness of 0.704nm. Our findings suggest that glass doped with silver ions is more hygienic than non-doped glass is, and should be applied to display screens and glassware. PMID:25837509

Shim, Gyu-In; Kim, Seong-Hwan; Eom, Hyung-Woo; Kim, Kwang-Mahn; Choi, Se-Young

2015-05-01

319

Flow pattern exchange in the Taylor-Couette system with a very small aspect ratio.  

PubMed

Numerical investigation is carried out on the flow pattern exchanges found in Taylor-Couette flows between two concentric rotating cylinders. The inner cylinder rotates while the outer cylinder and both end walls are stationary. The aspect ratio (column length/gap width) is small, and its range is from 0.5 to 1.6. Previous experimental results for this range of the aspect ratio showed that the steady flow patterns are classified into three groups: the normal two-cell mode, anomalous one-cell mode and twin-cell mode. All modes found by experiments are predicted in the present numerical calculation. Besides these three flow modes, an unsteady mode is predicted, which is time dependent and fully developed. The existence of the unsteady mode is also confirmed by our experiments. When the inner cylinder starts to rotate from rest, vortices at the corners of the inner cylinder and both end walls develop, and they induce the normal two-cell mode. The flow of the anomalous one-cell mode or twin-cell mode appears after an abrupt breakdown of symmetric two-cell mode flows. During the gradual deceleration of the inner cylinder, the transitions of flow modes occur. We observed mode transitions between the normal two-cell mode and anomalous one-cell mode and mode transitions from the twin-cell mode to the normal two-cell mode, anomalous one-cell mode, and unsteady mode. The critical loci where these mode transitions appear are determined. The numerical confirmation of the twin-cell mode is a different result obtained in the present study. PMID:11909243

Furukawa, Hiroyuki; Watanabe, Takashi; Toya, Yorinobu; Nakamura, Ikuo

2002-03-01

320

Evolution of ion-exchange: from Moses to the Manhattan Project to modern times.  

PubMed

This article explores the history of ion-exchange from records of desalination in the Old Testament and the writings of Aristotle, to the identification of the phenomenon of ion-exchange by two English agricultural chemists, to the invention of suppressed conductivity by Small et al. [Anal. Chem. 54 (1975) 462]. It then focuses on the characteristics of the gradual and continuous evolution of ion chromatography with suppressed conductivity to its current state, with an emphasis on those discoveries that punctuated or revolutionized this evolution. PMID:12877196

Lucy, Charles A

2003-06-01

321

Formation of silver nanoparticles on the silicate glass surface after ion exchange  

NASA Astrophysics Data System (ADS)

It has been experimentally shown that water vapor thermal treatment of silicate glasses with silver ions introduced by ion exchange leads to the formation of a silver nanoparticle layer with a high packing density on the glass surface. The results of studying the morphology of samples by atomic force and electron microscopy and X-ray spectral analysis of the composition of nanoparticles, as well as the optical density and luminescence spectra in different stages of the treatment, are presented. Mechanisms explaining the processes responsible for silver nanoparticle formation upon water vapor thermal treatment on the glass surface after ion exchange are proposed.

Obraztsov, P. A.; Nashchekin, A. V.; Nikonorov, N. V.; Sidorov, A. I.; Panfilova, A. V.; Brunkov, P. N.

2013-06-01

322

Automated resource-saving technology of ion-exchange water treatment  

NASA Astrophysics Data System (ADS)

Stable high quality of the purified water can be provided by adaptive control of water-treatment installations with the observer in a loop of the control system on the basis of observer of ion exchange processes. To obtain this goal the following problems have been solved: the hierarchic structure of water treatment system is developed; the system of water treatment quality criteria for ion exchange processes is developed; the created mathematical model of ionic exchange processes is functionally oriented to application in control system as an observer; methodologies of identification of a mathematical model of ionic exchange processes is developed; verification of the mathematical model of ionic exchange is performed on experimental-industrial basis; automatic control system of water treatment with observer in the loop is developed for low-waste installation of a heat supply system.

Livshits, M.

2015-01-01

323

Dual drug load and release behavior on ion-exchange fiber: influencing factors and prediction method for precise control of the loading amount.  

PubMed

Abstract Ion-exchange fiber undergoes a stoichiometric exchange reaction and has large exchange capability, which makes it a promising candidate as a multiple drug carrier. Because combinatorial effects can act synergistically, additively or antagonistically depending on the ratio of the agents being combined, the objective of this study was to learn the dual drug loading of ion-exchange fiber and develop a mathematical method for precisely control of the loading amount. Atenolol and Gatifloxacin, with different loading behaviors into strong cationic ion-exchange fiber ZB-1, were used to build a representative of dual loading. Not suitable pH value of drug solutions could make simultaneous loading fail, while the change of drug solution volume hardly affected the equilibrium. Ion-exchange groups occupied by the drug which owned lower affinity to fiber could be grabbed by the higher affinity drug, indicating the existence of competition between drugs. Thermodynamic model was introduced to guide the loading prediction and a favorable relevance had been shown between determined and predicted data. The release behaviors of each drug from dual drug-fiber complex were similar to those from single drug-fiber complexes. PMID:24841046

Yuan, Jing; Gao, Yanan; Liu, Tiaotiao; Wang, Xinyu; Liu, Hongzhuo; Li, Sanming

2014-05-19

324

21 CFR 173.25 - Ion-exchange resins.  

Code of Federal Regulations, 2010 CFR

...styrene and divinylbenzene. (2) Sulfonated anthracite coal meeting the requirements of ASTM method D388-38, Class I...base capacity by weight of total exchange capacity [Chemical Abstracts Service name: Oxirane (chloromethyl)-, polymer with...

2010-04-01

325

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

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

326

Ion-exchange sorption and preparative chromatography of biologically active materials  

SciTech Connect

This book presents information on the following topics: the problems of fine physico-chemical biotechnology; types of highly permeable network polyelectrolytes; methods for studying the permeability and porosity of network polyelectrolytes; the conformation state and flexibility of the structural elements of network polyelectrolytes; ion-exchange processes without the sorption of physiologically active substances; ion exchange, hydration, and swelling; nucleosides, nucleotides, alkaloids, sulfonamides, and miscellaneous physiologically active subtances; sharp front formation for the exchange of ions with the same valences; standard quasi-equilibrium frontal chromatography on ionites; sorption kinetics in ionites with structural heterogeneity; experimental investigations of the diffusivities of organic and physiologically active ions in ionite beads; and increasing the efficiency of low-pressure chromatography by using surface-layer and bidispersed ionites.

Samsonov, G.V.

1986-01-01

327

Fabrication of buried-type waveguide with optical gates by nano ion-exchange method  

NASA Astrophysics Data System (ADS)

Buried-type optical waveguide with blanches for the gate of optical signals was fabricated by nano ion-exchange method using the probe of atomic force microscope (AFM) as an electrode. 2-step procedure of the electric field-assisted Ag/Na-ion exchange followed by K/Na one was applied to prepare the waveguide structure inside the glass substrate. Pt-coated AFM probe as a cathode was attached to the glass surface and Ag+ ions in the core underneath the probe were partially extracted towards the glass surface. The protruding high index regions from the core towards the glass surface were found to work as the optical gate where the wavelength and intensity of light through the gate was determined by the condition of nano ion-exchange treatment.

Yano, Tetsuji; Shokatsu, Eiji; Segawa, Hiroyo; Shibata, Shuichi

2010-02-01

328

Biocompatibility Research of a Novel pH Sensitive Ion Exchange Resin Microsphere.  

PubMed

The main objective of this study was to investigate biocompatibility and provide in-vivo pharmacological and toxicological evidence for further investigation of the possibility of pH sensitive ion exchange resin microsphere for clinical utilizations. Acute toxicity study and general pharmacological studies were conducted on the pH sensitive ion exchange resin microsphere we prepared. The general pharmacological studies consist of the effects of the pH sensitive ion exchange resin microsphere on the nervous system of mice, the functional coordination of mice, the hypnosis of mice treated with nembutal at subliminal dose, the autonomic activities of tested mice, and the heart rate, blood pressure, ECG and breathing of the anesthetic cats. The LD50 of pH sensitive ion exchange resin microsphere after oral administration was more than 18.84 g·Kg(-1). Mice were orally administered with 16 mg·Kg(-1), 32 mg·Kg(-1) and 64 mg·Kg(-1) of pH sensitive ion exchange resin microsphere and there was no significant influence on mice nervous system, general behavior, function coordination, hypnotic effect treated with nembutal at subliminal dose and frequency of autonomic activities. Within the 90 min after 5 mg·Kg(-1), 10 mg·Kg(-1), 20 mg·Kg(-1) pH sensitive ion exchange resin microsphere was injected to cat duodenum, the heart rate, blood pressure, breathing and ECG of the cats didn't make significant changes in each experimental group compared with the control group. The desirable pharmacological and toxicological behaviors of the pH sensitive ion exchange resin microsphere exhibited that it has safe biocompatibility and is possible for clinical use. PMID:25276183

Liu, Hongfei; Shi, Shuangshuang; Pan, Weisan; Sun, Changshan; Zou, Xiaomian; Fu, Min; Feng, Yingshu; Ding, Hui

2014-01-01

329

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

PubMed

Rapid growth of chemical and biotechnology in diversified areas fuels the demand for the need of reliable green technologies for the down stream processes, which include separation, purification and isolation of the molecules. Ion-exchange membrane technologies are non-hazardous in nature and being widely used not only for separation and purification but their application also extended towards energy conversion devices, storage batteries and sensors etc. Now there is a quite demand for the ion-exchange membrane with better selectivities, less electrical resistance, high chemical, mechanical and thermal stability as well as good durability. A lot of work has been done for the development of these types of ion-exchange membranes during the past twenty-five years. Herein we have reviewed the preparation of various types of ion-exchange membranes, their characterization and applications for different electro-membrane processes. Primary attention has been given to the chemical route used for the membrane preparation. Several general reactions used for the preparation of ion-exchange membranes were described. Methodologies used for the characterization of these membranes and their applications were also reviewed for the benefit of readers, so that they can get all information about the ion-exchange membranes at one platform. Although there are large number of reports available regarding preparations and applications of ion-exchange membranes more emphasis were predicted for the usefulness of these membranes or processes for solving certain type of industrial or social problems. More efforts are needed to bring many products or processes to pilot scale and extent their applications. PMID:16325751

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

2006-02-28

330

Core-exchange effects in like-ion scattering  

Microsoft Academic Search

The influence of blocking on core-exchange effects is studied by examining several scattering systems, characterized by the common feature of having a small nucleon-number difference equal to 2. The analysis is performed in terms of a macroscopic model in which the intercluster potential employed contains a Majorana space-exchange component. The result shows that such influence is weak in the d

V. Shkolnik; Y. C. Tang

1983-01-01

331

Selective separation of sodium ions from a mixture with phenylalanine by Donnan dialysis with a profiled sulfogroup cation exchange membrane  

NASA Astrophysics Data System (ADS)

The possibility of separating ions of metal from a mixture with ampholyte (an amino acid) by Donnan dialysis with an MK-40 sulfogroup cation exchange membrane is demonstrated. Conditions ensuring the selectivity and intensity of the mass transfer of sodium ions from a mixture with bipolar phenylalanine ions into a diffusate containing hydrochloric acid through a cation exchange membrane are found.

Vasil'eva, V. I.; Goleva, E. A.

2013-11-01

332

Numerical modeling of field-assisted ion-exchanged channel waveguides by the explicit consideration of space-charge buildup.  

PubMed

A numerical model explicitly considering the space-charge density evolved both under the mask and in the region of optical structure formation was used to predict the profiles of Ag concentration during field-assisted Ag(+)-Na(+) ion exchange channel waveguide fabrication. The influence of the unequal values of diffusion constants and mobilities of incoming and outgoing ions, the value of a correlation factor (Haven ratio), and particularly space-charge density induced during the ion exchange, on the resulting profiles of Ag concentration was analyzed and discussed. It was shown that the incorporation into the numerical model of a small quantity of highly mobile ions other than exclusively Ag(+) and Na(+) may considerably affect the range and shape of calculated Ag profiles in the multicomponent glass. The Poisson equation was used to predict the electric field spread evolution in the glass substrate. The results of the numerical analysis were verified by the experimental data of Ag concentration in a channel waveguide fabricated using a field-assisted process. PMID:21833126

Mrozek, Piotr

2011-08-01

333

Numerical modeling of field-assisted ion-exchanged channel waveguides by the explicit consideration of space-charge buildup  

NASA Astrophysics Data System (ADS)

A numerical model explicitly considering the space-charge density evolved both under the mask and in the region of optical structure formation was used to predict the profiles of Ag concentration during field-assisted Ag+--Na+ ion exchange channel waveguide fabrication. The influence of the unequal values of diffusion constants and mobilities of incoming and outgoing ions, the value of a correlation factor (Haven ratio), and particularly space-charge density induced during the ion exchange, on the resulting profiles of Ag concentration was analyzed and discussed. It was shown that the incorporation into the numerical model of a small quantity of highly mobile ions other than exclusively Ag+ and Na+ may considerably affect the range and shape of calculated Ag profiles in the multicomponent glass. The Poisson equation was used to predict the electric field spread evolution in the glass substrate. The results of the numerical analysis were verified by the experimental data of Ag concentration in a channel waveguide fabricated using a field-assisted process.

Mrozek, Piotr

2011-08-01

334

Transpiration efficiency over an annual cycle, leaf gas exchange and wood carbon isotope ratio of three tropical tree species  

E-print Network

Transpiration efficiency over an annual cycle, leaf gas exchange and wood carbon isotope ratio; published online August 6, 2009 Summary Variation in transpiration efficiency (TE) and its relationship. Cumulative transpiration was determined by repeatedly weighing the pots with a pallet truck scale. Dry matter

Bermingham, Eldredge

335

Alkaline aluminum phosphate glasses for thermal ion-exchanged optical waveguide  

NASA Astrophysics Data System (ADS)

Alkaline aluminum phosphate glasses (NMAP) with excellent chemical durability for thermal ion-exchanged optical waveguide have been designed and investigated. The transition temperature Tg (470 °C) is higher than the ion-exchange temperature (390 °C), which is favorable to sustain the stability of the glass structure for planar waveguide fabrication. The effective diffusion coefficient De of K+-Na+ ion exchange in NMAP glasses is 0.110 ?m2/min, indicating that ion exchange can be achieved efficiently in the optical glasses. Single-mode channel waveguide has been fabricated on Er3+/Yb3+ doped NMAP glass substrate by standard micro-fabrication and K+-Na+ ion exchange. The mode field diameter is 9.6 ?m in the horizontal direction and 6.0 ?m in the vertical direction, respectively, indicating an excellent overlap with a standard single-mode fiber. Judd-Ofelt intensity parameter ?2 is 5.47 × 10-20 cm2, implying a strong asymmetrical and covalent environment around Er3+ in the optical glasses. The full width at half maximum and maximum stimulated emission cross section of the 4I13/2 ? 4I15/2 are 30 nm and 6.80 × 10-21 cm2, respectively, demonstrating that the phosphate glasses are potential glass candidates in developing compact optoelectronic devices. Pr3+, Tm3+ and Ho3+ doped NMAP glasses are promising candidates to fabricate waveguide amplifiers and lasers operating at special telecommunication windows.

Wang, Fei; Chen, Baojie; Pun, Edwin Yue Bun; Lin, Hai

2015-04-01

336

Online hydrogen/deuterium exchange performed in the ion mobility cell of a hybrid mass spectrometer.  

PubMed

The present paper describes the performance of online, gas-phase hydrogen/deuterium exchange implemented in the ion mobility cell of a quadrupole time-of-flight mass spectrometer. Deuterium oxide and deuterated methanol were utilized to create deuterated vapor that is introduced into the ion mobility region of the mass spectrometer. Hydrogen/deuterium exchange occurs spontaneously in the milliseconds time frame without the need of switching the instrument into ion mobility mode. The exchange was studied in case of low molecular weight molecules and proteins. The observed number of exchanged hydrogens was equal to the number of theoretically exchangeable hydrogens for all low molecular weight compounds. This method needs only minimal instrumental modifications, is simple, cheap, environment friendly, compatible with ultraperformance liquid chromatography, and can be implemented on commercially available instruments. It does not compromise choice of liquid chromatographic solvents and accurate mass or parallel-fragmentation (MS(E)) methods. The performance of this method was compared to that of conventional alternatives where the deuterated solvent is introduced into the cone gas of the instrument. Although the degree of exchange was similar between the two methods, the "cone gas method" requires 10 times higher deuterated solvent volumes (50 muL/min) and offers reduced sensitivity in the tandem mass spectrometry (MS/MS) mode. The presented method is suggested as a standard future element of mass spectrometers to aid online structural characterization of unknowns and to study conformational changes of proteins with hydrogen/deuterium exchange. PMID:19848411

Nagy, Kornél; Redeuil, Karine; Rezzi, Serge

2009-11-15

337

Anion selectivity in ion exchange reactions with surface functionalized ionosilicas.  

PubMed

Mesoporous imidazolium functionalized surface functionalized ionosilicas have been investigated as anion exchange materials for the adsorption of oxo-anions in aqueous media. We studied particularly pertechnetate adsorption and could show that solids bearing long chain substituted imidazolium groups are highly efficient anion exchange materials often displaying high distribution coefficients between solid and liquid phases. We observed that the distribution coefficient of pertechnetate is a function of the presence of competing anionic species. As a consequence, our experiments allowed reproducing experimentally Hofmeister's series. However, pertechnetate adsorption on the material can completely be inhibited in the presence of highly fluorinated anions such as bis(trifluoromethylsulfonyl)amide (NTf2). This behaviour indicates a particularly imidazophilic behaviour of these anions, which have a particular importance due to their use in water immiscible ionic liquids. Finally, the adsorption process has been shown to be reversible. This feature is of importance in view of the regeneration of the anion exchange material. PMID:25793553

Petrova, Maria; Guigue, Mireille; Venault, Laurent; Moisy, Philippe; Hesemann, Peter

2015-04-01

338

Synthesis, characterization and analytical applications of lead (II) selective polyacrylonitrile thorium (IV) phosphate: a novel fibrous ion exchanger  

Microsoft Academic Search

Some investigations on the preparative procedures of fibrous polyacrylonitrile thorium (IV) phosphate (PANThP) are reported. This new fibrous ion exchanger has been characterized on the basis of SEM and the ion exchange studies. The distribution studies reveal that the exchanger is highly selective for Pb(II). On this basis some useful binary separations of Pb(II) from other metal ions have been

K. G Varshney; Namrta Tayal; A. A Khan; R Niwas

2001-01-01

339

Variations in K{sup +}-Na{sup +} ion exchange depth in commercial and experimental float glass compositions  

SciTech Connect

The authors report the results of ion-exchange experiments conducted on 17 commercial soda-lime-silicate (SLS) float glass and 8 experimental SLS glass compositions. A significant variation in the depth of K{sup +} penetration with relatively small changes in composition was observed. The data were fit to a multiple regression model in which the major oxides are the independent variables and depth of K{sup +} is the dependent variable. The model indicates that increased depth of exchange (increased interdiffusion coefficient) correlates predominantly with increased K{sub 2}O and/or Na{sub 2}O content of the glass, with a decreased total alkaline earth content and with the ratio of CaO/MgO.

Sinton, C.W.; LaCourse, W.C.; O'Connell, M.J.

1999-12-01

340

Development and Evaluation of Sustained Release Tablet of Betahistine Hydrochloride Using Ion Exchange Resin Tulsion T344  

PubMed Central

An attempt was made to sustain the release of Betahistine hydrochloride by complexation technique using strong cation-exchange resin, Tulsion T344. The drug loading onto ion-exchange resin was optimized for mixing time, activation, effect of pH, swelling time, ratio of drug?:?resin, and temperature. The resinate was evaluated for micromeritic properties and characterized using XRPD and IR. For resinate sustained release tablets were formulated using hydoxypropyl methylcellulose K100M. The tablets were evaluated for hardness, thickness, friability, drug content, weight variation, and in vitro drug release. Tablets thus formulated (Batch T-3) provided sustained release of drug over a period of 12?h. The release of Betahistine HCl from resinate controls the diffusion of drug molecules through the polymeric material into aqueous medium. Results showed that Betahistine HCl was formulated into a sustained dosage form as an alternative to the conventional tablet. PMID:22779010

Wagh, Vijay D.; Pawar, Nilesh

2012-01-01

341

Development and evaluation of sustained release tablet of betahistine hydrochloride using ion exchange resin tulsion t344.  

PubMed

An attempt was made to sustain the release of Betahistine hydrochloride by complexation technique using strong cation-exchange resin, Tulsion T344. The drug loading onto ion-exchange resin was optimized for mixing time, activation, effect of pH, swelling time, ratio of drug?:?resin, and temperature. The resinate was evaluated for micromeritic properties and characterized using XRPD and IR. For resinate sustained release tablets were formulated using hydoxypropyl methylcellulose K100M. The tablets were evaluated for hardness, thickness, friability, drug content, weight variation, and in vitro drug release. Tablets thus formulated (Batch T-3) provided sustained release of drug over a period of 12?h. The release of Betahistine HCl from resinate controls the diffusion of drug molecules through the polymeric material into aqueous medium. Results showed that Betahistine HCl was formulated into a sustained dosage form as an alternative to the conventional tablet. PMID:22779010

Wagh, Vijay D; Pawar, Nilesh

2012-01-01

342

Sorption of beryllium from fluorine-containing solutions by amino-phosphonate amphoteric ion-exchange resins  

SciTech Connect

Sorption of beryllium ions by a series of amino-phosphonate amphoteric ion-exchange resins from BeF/sub 2/ solutions containing HF, NH/sub 4/F.HF, and NH/sub 4/F has been studied. The influence of the salt form of the resin, concentration of fluoride ions, and beryllium content in the original solutions was demonstrated. The mechanism of ion exchange on amphoteric ion-exchangers was postulated on the basis of chemical analysis and sorption and IR-spectroscopic data. Conclusions are drawn regarding the participation of phosphorus-containing groups of the resins in exchange. Data are presented on desorption of complex fluoride ions and beryllium from amphoteric ion-exchange resins by solutions of hydrofluoric, hydrochloric, and sulfuric acids, ammonium fluoride, and ammonium hydrogenfluoride.

Pakholkov, V.S.; Rychkov, V.N.

1981-10-20

343

Ion exchange determines iodine-131 concentration in aqueous samples  

NASA Technical Reports Server (NTRS)

Inorganic radioiodide in aqueous media is analyzed by separating the radioactive iodine-131 as the iodide ion on a silver chloride column. The activity in the final precipitate may be determined by beta or gamma counting.

Fairman, W. D.; Sedlet, J.

1967-01-01

344

Effect of the type of ion exchange membrane on performance, ion transport, and pH in biocatalyzed electrolysis of wastewater.  

PubMed

Previous studies have shown that the application of cation exchange membranes (CEMs) in bioelectrochemical systems running on wastewater can cause operational problems. In this paper the effect of alternative types of ion exchange membrane is studied in biocatalyzed electrolysis cells. Four types of ion exchange membranes are used: (i) a CEM, (ii) an anion exchange membrane (AEM), (iii) a bipolar membrane (BPM), and (iv) a charge mosaic membrane (CMM). With respect to the electrochemical performance of the four biocatalyzed electrolysis configurations, the ion exchange membranes are rated in the order AEM > CEM > CMM > BPM. However, with respect to the transport numbers for protons and/or hydroxyl ions (t(H/OH)) and the ability to prevent pH increase in the cathode chamber, the ion exchange membranes are rated in the order BPM > AEM > CMM > CEM. PMID:18547927

Rozendal, R A; Sleutels, T H J A; Hamelers, H V M; Buisman, C J N

2008-01-01

345

Ion extraction and charge exchange in laser isotope separation  

Microsoft Academic Search

In the atomic vapor laser isotope separation (AVLIS) process, a vapor is ionized by pulsed laser beams, and the ions are extracted by negatively biased collectors. We compute the unsteady dynamics of the photoplasma using a two-dimensional (2-D) particle-in-cell (PIC) code. Collisions between ions and neutral species are simulated by a Monte Carlo technique. The plasma dynamics is visualized by

Dominique Hostein; F. Doneddu

1996-01-01

346

NITRATE REMOVAL FROM WATER SUPPLIES BY ION EXCHANGE - EXECUTIVE SUMMARY  

EPA Science Inventory

Anion exchange using synthetic organic resins is a proven and practical technology for the removal of nitrate from water supplies. However, disposal of the spent regenerant brime solution containing nitrate is a potential problem. Two processes were examined in detail in this rep...

347

Improved hydrous oxide ion-exchange compound catalysts  

DOEpatents

Disclosed is 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 exchanged with a catalytically effective quantity of a catalyst metal, and which has been subsequently treated with a solution of a Bronsted acid.

Dosch, R.G.; Stephens, H.P.

1986-04-09

348

Preparation of catalysts via ion-exchangeable coatings on supports  

DOEpatents

Disclosed are: new catalytic compositions which comprise an inert support coated with a hydrous alkali metal, alkaline earth metal, or quaternary ammonium titanate, niobate, zirconate, or tantalate, in which the alkali or alkaline earth metal or quaternary ammonium cations have been exchanged for a catalytically effective quantity of a catalytically effective metal.

Dosch, R.G.; Stephens, H.P.

1986-04-09

349

BARIUM AND RADIUM REMOVAL FROM GROUNDWATER BY ION EXCHANGE  

EPA Science Inventory

The primary objective of this study was to determine the applicability of weak acid exchange resin in the hydrogen form for removal of hardness, barium and radium from groundwater. Weak acid resin in the hydrogen form eliminates the addition of sodium to drinking water. The capac...

350

Modification of acid sites in ZSM-5 by ion-exchange: An in-situ FTIR study  

NASA Astrophysics Data System (ADS)

A study of the acid sites in Mn+-ZSM-5 zeolites (Mn+ = H+, Al3+, Ca2+, and Ba2+), synthesized by ion-exchange from the NH4+ form, has been carried out using X-ray diffraction, 27Al MAS NMR, and in-situ FTIR spectroscopy. X-ray diffraction data indicate that the crystalline structure of ZSM-5 is maintained on ion-exchange. 27Al MAS NMR spectroscopy confirms that Lewis acid sites in all of the Mn+-ZSM-5 zeolites are mainly located on the tetrahedral aluminum atoms in the zeolite framework. However, octahedral extra-framework aluminum is another source of Lewis acid sites in H+-ZSM-5 and Al3+-ZSM-5. Brønsted acid sites are identified as originating from the hydroxyl groups that bridge Al and Si atoms. The acid sites in Mn+-ZSM-5 have been characterized by in-situ FTIR spectroscopy with pyridine as the probe molecule. FTIR spectroscopy demonstrated that the number of accessible acid sites and ratio of Lewis to Brønsted acid sites in Mn+-ZSM-5 can be effectively modified by ion-exchange. The number of acid sites in Mn+-ZSM-5 increases in the same order as the acidity of cations with Ba2+ < Ca2+ < NH4+ < Al3+ < H+. Though the strength of both Lewis and Brønsted acid sites is virtually identical for all Mn+-ZSM-5 zeolites, the ratio of Brønsted to Lewis acid sites varies as a result of the loaded cation. In addition, modification of acid sites in Mn+-ZMS-5 by loading different cations is discussed in terms of the accessibility of the surface of the zeolite channels and the reactivity of the cations with Brønsted acid hydroxyls. We conclude that larger cations can effectively constrict the zeolite channels and impede the ability of pyridine to access acid sites on the surface of the channels.

Wu, Weiqiang; Weitz, Eric

2014-10-01

351

Ion-exchange and selectivity behavior of thermally treated and. gamma. -irradiated phases of zirconium(IV) arsenophosphate cation exchanger: separation of Al(III) from some metal ions and removal of cations from water  

SciTech Connect

Ion-exchange and selectivity behavior of zirconium(IV) arsenophosphate (ZAP) has been studied systematically after thermal and irradiation treatments. As a result, an increase in the ion-exchange capacity and a complete reversal in the selectivity sequence for some common metal ions has been observed on heating. The modified phase of ZAP has been utilized successfully for the quantitative separation of aluminum from numerous metal ions and for the removal of cations from water. 5 figures, 3 tables.

Varshney, K.G.; Varshney, K.; Agrawal, S.

1983-01-01

352

Magnetic exchange interaction between rare-earth and Mn ions in multiferroic hexagonal manganites  

SciTech Connect

The authors report a study of magnetic dynamics in multiferroic hexagonal manganite HoMnO{sub 3} by far-infrared spectroscopy. Low-temperature magnetic excitation spectrum of HoMnO{sub 3} consists of magnetic-dipole transitions of Ho ions within the crystal-field split J = 8 manifold and of the triangular antiferromagnetic resonance of Mn ions. They determine the effective spin Hamiltonian for the Ho ion ground state. The magnetic-field splitting of the Mn antiferromagnetic resonance allows us to measure the magnetic exchange coupling between the rare-earth and Mn ions.

Talbayev, Diyar [Los Alamos National Laboratory; Trugman, Stuart A [Los Alamos National Laboratory; Taylor, Antoinette J [Los Alamos National Laboratory; Averitt, Richard D [Los Alamos National Laboratory; Namjung, Hur [INHA UNIV; Andrew, Laforge D [UCSD; Dimitri, Basov N [UCSD

2008-01-01

353

The nature of ion exchange selectivity of phenol-formaldehyde sorbents with respect to cesium and rubidium ions  

NASA Astrophysics Data System (ADS)

The structure of aqua complexes of alkali metal ions Me+(H2O) n , n = 1-6, where Me is Li, Na, K, Rb, and Cs, and complexes of 2,6-dimethylphenolate anion (CH3)2PhO- selected as a model of the elementary unit of phenol-formaldehyde ion exchanger with hydrated alkali metal cations Me+(H2O) n , n = 0-5, was studied by the density functional method. The energies of successive hydration of the cations and the energies of binding of alkali metal hydrated cations with (CH3)2PhO- depending on the number of water molecules n were calculated. It was shown that the dimethylphenolate ion did not have specific selectivity with respect to cesium and rubidium ions. The energies of hydration and the energies of binding of alkali metal cations with (CH3)2PhO- decreased in the series Li+ > Na+ > K+ > Rb+ > Cs+ as n increased. The conclusion was drawn that the reason for selectivity of phenol-formaldehyde and other phenol compounds with respect to cesium and rubidium ions was the predomination of the ion dehydration stage in the transfer from an aqueous solution to the phenol phase compared with the stage of binding with ion exchange groups.

Kargov, S. I.; Shelkovnikova, L. A.; Ivanov, V. A.

2012-05-01

354

Structure simulation into a lamellar supramolecular network and calculation of the metal ions/ligands ratio  

PubMed Central

Background Research interest in phosphonates metal organic frameworks (MOF) has increased extremely in the last two decades, because of theirs fascinating and complex topology and structural flexibility. In this paper we present a mathematical model for ligand/metal ion ratio of an octahedral (Oh) network of cobalt vinylphosphonate (Co(vP)·H2O). Results A recurrent relationship of the ratio between the number of ligands and the number of metal ions in a lamellar octahedral (Oh) network Co(vP)·H2O, has been deducted by building the 3D network step by step using HyperChem 7.52 package. The mathematical relationship has been validated using X ray analysis, experimental thermogravimetric and elemental analysis data. Conclusions Based on deducted recurrence relationship, we can conclude prior to perform X ray analysis, that in the case of a thermogravimetric analysis pointing a ratio between the number of metal ions and ligands number around 1, the 3D network will have a central metal ion that corresponds to a single ligand. This relation is valid for every type of supramolecular network with divalent metal central ion Oh coordinated and bring valuable information with low effort and cost. PMID:22932493

2012-01-01

355

Low aspect ratio tokamak startup and heating using waves in the ion cyclotron range of frequencies  

Microsoft Academic Search

Radio Frequency auxiliary heating for Low Aspect Ratio Tokamaks can facilitate startup and access to high energy density plasmas, reduce the demand on ohmic core volt-seconds, and provide off axis electron heating for a high betae plasma. Calculations for several waves both below and at high harmonics of the ion cyclotron frequency predict significant RF heating even at the lower

T. Intrator; R. Fonck; G. Garstka; B. Lewicki; A. Sontag; T. Thorson; K. Tritz; C. Wilson; G. R. Winz

1997-01-01

356

Effects of annealing electric field assisted ?-? ion exchanged soda-lime glass guides  

NASA Astrophysics Data System (ADS)

Soda-lime glass samples have been subjected to either a thermal or an electric field assisted 0022-3727/32/6/009/img3 ion exchange. The effective refractive indices of the modes supported by the guides have been measured using a prism coupler before and after annealing and refractive index profiles have been reconstructed from the data. The effective refractive indices of the modes for guides produced by electric field assisted exchange exhibit an unusual evolution with annealing time. The area under the refractive index profiles produced from the measurements shows a significant reduction with annealing time. These features are not present in samples prepared by thermal ion exchange. The results are attributed to a relaxation mechanism operative only within regions of the glass that have been subjected to field assisted 0022-3727/32/6/009/img4 ion injection.

Oven, R.; Batchelor, S.; Ashworth, D. G.

1999-03-01

357

Structural changes of soda-lime silica glass induced by a two-step ion exchange  

NASA Astrophysics Data System (ADS)

Introduction of silver or copper ions in soda-lime silica glass has been investigated by studying the data obtained from optical absorption measurements and the transmission electron microscopy performances. It has been stated that the optical and structural characteristics of the doped specimens are effectively controlled by the dopant concentrations and parameters of both, the ion-exchange procedures and the annealing treatments applied afterwards. By sequential ion exchange of as received specimens in molten baths of Cu2Cl2 and (AgNO3 in NaNO3), the composition and electronic structure of the elemental-nanoclusters have been altered. Moreover, depending on the order of annealing, different microstructures were created in the fabricated composites. Like this, the two-step exchange determines a new engineering way new materials with desired optical properties could be produced.

Suszynska, M.; Krajczyk, L.; Macalik, B.

2010-11-01

358

Ion exchange chromatography and radioimmunoassay procedure for measuring opioid peptides and substance P  

SciTech Connect

The measurements of peptides of the enkephalin, dynorphin and substance P systems is complicated by the number of possible precursor fragments and degradation products that might cross-react with the antisera. By using an ion-exchanger step before radioimmunoassay one can reduce the possibility that observed peptide levels are due to precursors or metabolites. The ion-exchanger method runs with good recovery and its main advantage is that many samples can be run in parallel. The recovery from the ion-exchanger was similar using two different homogenizing media, whereas the measured endogenous levels of (Met) and (Leu)enkephalin were 3-4 fold higher with 1M acetic acid than when a 1:1 MeOH/HCl mixture was used for tissue extraction.

Bergstroem, L.; Christensson, I.; Folkesson, R.; Stenstroem, B.; Terenius, L.

1983-10-01

359

Sorption of iron(III) from chromate solution by the aminocarboxylic ion exchanger ANKB-2  

SciTech Connect

The possibility of iron(III) sorption by the amphoteric ion exchanger ANKB-2 from chromate solution and its superiority over the cation exchanger KU-23 (10/60) have been demonstrated. By means of IR spectroscopy it has been shown that iron(III) sorption from chromate solution by ANKB-2 proceeds via both ionic and coordination reactions. The proportion of these kinds of reaction does not depend on the Cr(VI) content of the initial solution.

Stoyanova, O.F.; Izmailova, D.R.; Kurolap, N.S.; Uglyanskaya, V.A.

1986-12-20

360

Ion exchange equilibria of heavy metals in aqueous solution on new chelating resins of sporopollenin  

Microsoft Academic Search

Studies have been conducted on the sorption of several heavy metal ions Cu(II), Ni(II), Zn(II), Cd(II) and Al(III) from aqueous solutions on the new chelating exchangers of sporopollenin (Lycopodium clavatum) as a function of pH at several temperatures between 20 and 50°C. The novel metal-ligand exchange resins possessing oxime and carboxylic acid side arm functionality were prepared through the reaction

M. Ersoz; E. Pehlivan; H. J. Duncan; S. Yildiz; M. Pehlivan

1995-01-01

361

Measuring surface-area-to-volume ratios in soft porous materials using laser-polarized xenon interphase exchange NMR  

E-print Network

We demonstrate a minimally invasive nuclear magnetic resonance (NMR) technique that enables determination of the surface-area-to-volume ratio (S/V) of soft porous materials from measurements of the diffusive exchange of laser-polarized 129Xe between gas in the pore space and 129Xe dissolved in the solid phase. We apply this NMR technique to porous polymer samples and find approximate agreement with destructive stereological measurements of S/V obtained with optical confocal microscopy. Potential applications of laser-polarized xenon interphase exchange NMR include measurements of in vivo lung function in humans and characterization of gas chromatography columns.

J. P. Butler; R. W. Mair; S. Patz; D. Hoffmann; M. I. Hrovat; R. A. Rogers; G. P. Topulos; R. L. Walsworth

2001-08-21

362

Deviations of the K ?/K ? intensity ratio of Ti upon impact with low velocity ions  

NASA Astrophysics Data System (ADS)

Deviations of the branching ratio of the decay of K-vacancies in Ti have been observed during bombardment with low velocity ions of H, He and N. Beams of these ions have been used for various applications in which resonant nuclear reactions were used as the main analytical technique, whereas the X-ray signal could conveniently be used for monitoring the accumulated charge. During the evaluation of this monitoring signal, it was observed that the commonly made assumption that the K ?/K ? intensity ratio is a constant can easily be off by 30% or more. Also a few data of L-shell ionisation cross sections has been measured on Au to establish if the onset of deviations in the branching ratio parallels the onset of deviations from the ECPSSR theory for inner shell ionisation.

Wijsman, W. E.; Vis, R. D.

1999-04-01

363

RESORCINOL-FORMALDEHYDE ION EXCHANGE RESIN CHEMISTRY FOR HIGH LEVEL WASTE TREATMENT  

SciTech Connect

A principal goal at the Savannah River Site is to safely dispose of the large volume of liquid nuclear waste held in many storage tanks. In-tank ion exchange technology is being considered for cesium removal using a polymer resin made of resorcinol formaldehyde that has been engineered into microspheres. The waste under study is generally lower in potassium and organic components than Hanford waste; therefore, the resin performance was evaluated with actual dissolved salt waste. The ion exchange performance and resin chemistry results are discussed.

Nash, C.; Duignan, M.

2010-01-14

364

Waste treatment by ion-exchange. (Latest citations from Pollution abstracts). Published Search  

SciTech Connect

The bibliography contains citations concerning wastewater treatment by ion-exchange techniques. Methods for removing metals, nitrates, phosphates, fluorides, and organic pollutants are described. Applications of this technology to the electroplating, metal finishing, pulp, paper, and other industries are included. The citations examine the commercial feasibility of using ion-exchange methods for pollutant reduction when the process is used alone or in combination with various pretreatment techniques. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1996-10-01

365

Waste treatment by ion-exchange. (Latest citations from Pollution abstracts). Published Search  

SciTech Connect

The bibliography contains citations concerning wastewater treatment by ion-exchange techniques. Methods for removing metals, nitrates, phosphates, fluorides, and organic pollutants are described. Applications of this technology to the electroplating, metal finishing, pulp, paper, and other industries are included. The citations examine the commercial feasibility of using ion-exchange methods for pollutant reduction when the process is used alone or in combination with various pretreatment techniques. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1995-09-01

366

Ni-Cu ion exchange observed for Ni(II)-porphyrins on Cu(111).  

PubMed

A Ni-Cu ion exchange has been observed for (5,15-dibromo-10,20-diphenylporphyrinato)nickel(II) (NiDBrDPP) and (5,10,15,20-tetrakis(4-bromophenyl)porphyrinato)nickel(II) (NiTBrPP) on Cu(111). The ion exchange proceeds at a faster rate for the NiDBrDPP/Cu(111) system compared to NiTBrPP/Cu(111). This is explained in terms of the macrocycle-substrate distance and the distortions that occur when the molecules are deposited on the Cu(111) surface. PMID:24548915

Doyle, Catherine M; Cunniffe, John P; Krasnikov, Sergey A; Preobrajenski, Alexei B; Li, Zheshen; Sergeeva, Natalia N; Senge, Mathias O; Cafolla, Attilio A

2014-04-01

367

Tagged hypervalent iodine reagents: a new purification concept based on ion exchange through SN2 substitution.  

PubMed

The preparation of phenylsulfonate-tagged iodine(III) reagents as well as their use in a novel purification strategy for iodine(III)-promoted reactions is described. The concept is based on ion exchange and is initiated by an azide-promoted SN2-reaction at the alkyl sulfonate followed by trapping of the resulting aryl sulfonate anion with an ion-exchange resin. The concept is successfully proven for Ru-catalyzed oxidations of alcohols, the activation and glycosidation of thioglycosides, and the SuArez reaction of pyranoses. PMID:17999512

Kunst, Eike; Gallier, Florian; Dujardin, Gilles; Yusubov, Mekhman S; Kirschning, Andreas

2007-12-01

368

Channel waveguides on RbTiOPO4 by Cs+ ion exchange.  

PubMed

In this Letter we report Cs(+) ion exchange channel waveguides on RbTiOPO(4) (RTP) for what we believe is the first time. A Ti channel mask was fabricated on an RTP substrate by conventional photolithography. The ion exchange process was carried out in a CsNO(3) melt, and the channels produced ranged from 6 to 11 ?m in width. The near-field pattern of the modes was recorded, and type II second harmonic generation in waveguide regime was obtained, producing 512.5 nm green light. The optical characterization shows optical losses of 3.8 dB/cm. PMID:23381425

Cugat, J; Solé, R; Carvajal, J J; Mateos, X; Massons, J; Lifante, G; Díaz, F; Aguiló, M

2013-02-01

369

Summary of Testing of SuperLig 639 at the TFL Ion Exchange Facility  

SciTech Connect

A pilot scale facility was designed and built in the Thermal Fluids Laboratory at the Savannah River Technology Center to test ion exchange resins for removing technetium and cesium from simulated Hanford Low Activity Waste (LAW). The facility supports the design of the Hanford River Protection Project for BNFL, Inc. The pilot scale system mimics the full-length of the columns and the operational scenario of the planned ion exchange system. Purposes of the testing include confirmation of the design, evaluation of methods for process optimization and developing methods for waste volume minimization. This report documents the performance of the technetium removal resin.

Steimke, J.L.

2000-12-19

370

Ligand-exchange chromatography of aromatic amines on resin-bound cobalt ion  

SciTech Connect

The use of cobalt metal for the selective separation of aromatic amines is completed with a chemically bonded diamine and glyoxime functional groups onto Lycopodium clavatum. Oximes and amines are excellent complexing agents for transition metal ions. Cobalt(II) metal ions can easily be immobilized on bis-diaminoethyl-glyoximated sporopollenin (bDAEG-sporopollenin). The ligand-exchange behavior of modified Lycopodium clavatum with respect to aromatic amines was investigated. This will permit the evaluation of bDAEG-sporopollenin ligand exchangers for their utilization as sorbents in the recovery, pollution control, and elimination of amines from wastewater.

Pehlivan, E.; Vural, U.S.; Ayar, A.; Yildiz, S. [Selcuk Univ., Konya (Turkey)

1996-06-01

371

Ion-exchange characteristics of sodium-calcium-silicate glass: Calculation from mode spectra  

NASA Astrophysics Data System (ADS)

The characteristics of silver-sodium ion exchange in standard commercial sodium-calcium-silicate glass are investigated using mode spectroscopy. The activation energy of the process, the silver-sodium interdiffusion coefficient, and the dependence of the maximal modulation of the refractive index on the silver nitrate concentration in the experimental salt bath are determined. The data set presented here makes it possible to specify the conditions for the formation of ion-exchange optical structures with preset parameters based on the glasses studied here.

Zhurikhina, V. V.; Petrov, M. I.; Sokolov, K. S.; Shustova, O. V.

2010-10-01

372

Separation of vanadium isotopes by ion-exchange chromatography.  

PubMed

Cation-exchange displacement chromatography of VO2+ was carried out for studying vanadium isotope effects in carboxylate ligand-exchange systems. The heavier isotope 51V was enriched in the carboxylate complex solution. The isotope separation coefficients epsilon(= alpha-1) for 50V/51V were 2.2 x 10(-4) and 2.4 x 10(-4) for citrate and lactate systems at 298 K, respectively. These values are much larger than those obtained in a previous study on the malate system. The existence of binuclear complexes of VO2+ may create the conditions for larger isotope fractionation. From the viewpoint of the process development of isotope separation, the heights equivalent to a theoretical plate of these processes were analyzed and found to be very small in each system due to the homogeneous, small and highly porous resin used. Citrate may be better than the other tested systems for the vanadium isotope separation. PMID:12641293

Zhang, Yong-Hong; Nomura, Masao; Aida, Masao; Fujii, Yasuhiko

2003-03-01

373

IOn-exchange behaviour of several elements in mixed solvents.  

PubMed

The distribution coefficients between the cation- and anion-exchangers Dowex 50 and Dowex 1, and aqueous solutions containing nitric or hydrochloric acid and organic solvents with or without amines or complexing agents, have been obtained for a number of metals including uranium, thorium, cerium, iron, copper, and nickel. The organic solvents were methanol, acetone and dimethylformamide; the amines were tributylamine and tribenzylamine, and the complexing agents EDTA and citric acid. Both batch and column methods were used. PMID:18960216

Cummings, T; Korkisch, J

1967-10-01

374

Building 579 waste ion exchange facility characterization report  

SciTech Connect

External direct surveys were performed for elevated {gamma} levels with a PG2 portable detector connected to a PRM 5-3 meter and for elevated {alpha} and {beta} levels with an NE portable detector. No {gamma} activity above background was detected. Several locations, the floor and west wall of building 579 and the manhole, had low levels of {beta} activity, up to 87 {+-} 49 dis/min. These values are below the allowable residual surface contamination limits for removable beta activity. There is water in the Mixed Bed Exchange Vessel, the Cation Exchange Vessel, the Closed Drain Tank, the manhole and some of the pipes. The accessible internal surfaces of the pipes, tanks and columns had higher levels of {beta} activity up to 172 {+-} 52 dis/min and some {alpha} activity up to 106 {+-} 29 dis/min. After the water is removed from the vessels, tanks, and lines, they should be surveyed to determine whether the areas accessible for smear surveys are representative of the general inside contamination levels. There are elevated levels of radionuclides in the resin from the Cation Exchange Vessel and in the water from the manhole. Since the radionuclide concentrations in the manhole water are less than ten times the site release criteria, it does not need any processing before it is released to the onsite drains. Although there are RCRA metals on the resin in the Cation Exchange Vessel, the amount that is removed during a leaching analysis is below the toxicity Characteristic level. Therefore, the resin is a radioactive waste not a mixed waste.

Sholeen, C.M.; Geraghty, D.C.

1997-03-01

375

Advance Workflow in Lipoproteomics via Polymeric Ion Exchanger.  

PubMed

A workflow is designed for the analysis of lipoproteins, high density lipoproteins (HDL), apoproteins, and lipid fraction, employing an organic polymeric anion exchanger through the enrichment of lipoproteins/peptides from serum. Polymeric separation media are chemically stable over the wide pH range. Poly(GMA/DVB), poly(GMA/EGDMA), and poly(GPE/DVB) are synthesized by radical polymerization, derivatized as strong anion exchangers, and used for lipoproteins enrichment. Lipoprotein's surface is covered by phospholipids, having phosphate groups, therefore lipoproteins are enriched by the interaction of anion exchanger with the phosphate groups and eluted at the pH of 7.5. HDL are further isolated by precipitating the very low-density lipoproteins (VLDL) and low-density lipoproteins (LDL) with phosphotungstic acid as precipitating reagent, followed by delipidation via liquid/liquid extraction. Apolipoproteins profiling is done by MALDI-MS, and lipids are analyzed using gold nanoparticles in the LDI-MS process. This study introduces a lipoproteomics work flow in separation science which analyses the intact lipoproteins. Furthermore, solid phase extraction (SPE)-based methodology is reported for the first time in lipoproteomics. Use of organic polymers, high reproducibility, detailed analysis of lipoproteins, apoproteins/peptides, and lipids from the single serum sample are the distinctive features of this workflow. Being biomarkers of numerous diseases, lipoproteins have clinical significance, and this workflow can be used at diagnostic and therapeutic levels. PMID:25674923

Javeed, Rabia; Jabeen, Fahmida; Saeed, Hira; Najam-Ul-Haq, Muhammad

2015-03-17

376

Studies of negative ions by collision-induced decomposition and hydrogen-deuterium exchange techniques.  

PubMed

Development of two new techniques for studying the gas phase chemistry of negative ions is reported. Collision induced dissociation (CID) of (M-1)- ions has been accomplished in a newly constructed triple stage quadrupole mass spectrometer. This instrument was assembled by adding two additional Finnigan quadrupole mass filters to a Finnigan Model 3200 CI mass spectrometer. Generation of (M-1)- ions is accomplished by allowing OH- and sample to react under CI conditions in the ion source. The first quadrupole mass filter, Q1, is then employed to selectively pass the (M-1)- ion into a second quadrupole filter containing argon or neon at 10(-3) torr. On collision with the inert gas the (M-1)- ions dissociate into fragments which are then mass analyzed in the third quadrupole filter, CID spectra of (M-1)- ions from twelve carbonyl compounds are presented in this paper. Ion molecule isotope exchange reactions in the CI ion source can be used to count the number of hydrogen atoms in many different chemical environments. Collisions between sample (M-1)- ions and deuterium-labeled reagent gases (ND3, D2O, EtOD) facilitate incorporation of deuterium into the negative ion if the basicities of the sample and reagent anions are similar. Thus it is possible to selectively incorporate deuterium into many organic samples by controlling the exothermicity of the acid base, ion-molecule chemistry. PMID:7428745

Hunt, D F; Sethi, S K; Shabanowitz, J

1980-06-01

377

Studies of negative ions by collision-induced decomposition and hydrogen-deuterium exchange techniques.  

PubMed Central

Development of two new techniques for studying the gas phase chemistry of negative ions is reported. Collision induced dissociation (CID) of (M-1)- ions has been accomplished in a newly constructed triple stage quadrupole mass spectrometer. This instrument was assembled by adding two additional Finnigan quadrupole mass filters to a Finnigan Model 3200 CI mass spectrometer. Generation of (M-1)- ions is accomplished by allowing OH- and sample to react under CI conditions in the ion source. The first quadrupole mass filter, Q1, is then employed to selectively pass the (M-1)- ion into a second quadrupole filter containing argon or neon at 10(-3) torr. On collision with the inert gas the (M-1)- ions dissociate into fragments which are then mass analyzed in the third quadrupole filter, CID spectra of (M-1)- ions from twelve carbonyl compounds are presented in this paper. Ion molecule isotope exchange reactions in the CI ion source can be used to count the number of hydrogen atoms in many different chemical environments. Collisions between sample (M-1)- ions and deuterium-labeled reagent gases (ND3, D2O, EtOD) facilitate incorporation of deuterium into the negative ion if the basicities of the sample and reagent anions are similar. Thus it is possible to selectively incorporate deuterium into many organic samples by controlling the exothermicity of the acid base, ion-molecule chemistry. PMID:7428745

Hunt, D F; Sethi, S K; Shabanowitz, J

1980-01-01

378

Patchiness of ion-exchanged mica revealed by DNA binding dynamics at short length scales  

NASA Astrophysics Data System (ADS)

The binding of double-stranded (ds) DNA to mica can be controlled through ion-exchanging the mica with divalent cations. Measurements of the end-to-end distance of linear DNA molecules discriminate whether the binding mechanism occurs through 2D surface equilibration or kinetic trapping. A range of linear dsDNA fragments have been used to investigate length dependences of binding. Mica, ion-exchanged with Ni(II) usually gives rise to kinetically trapped DNA molecules, however, short linear fragments (<800 bp) are seen to deviate from the expected behaviour. This indicates that ion-exchanged mica is heterogeneous, and contains patches or domains, separating different ionic species. These results correlate with imaging of dsDNA under aqueous buffer on Ni(II)-mica and indicate that binding domains are of the order of 100 nm in diameter. Shorter DNA fragments behave intermediate to the two extreme cases of 2D equilibration and kinetic trapping. Increasing the incubation time of Ni(II) on mica, from minutes to hours, brings the conformations of the shorter DNA fragments closer to the theoretical value for kinetic trapping, indicating that long timescale kinetics play a role in ion-exchange. X-ray photoelectron spectroscopy (XPS) was used to confirm that the relative abundance of Ni(II) ions on the mica surface increases with time. These findings can be used to enhance spatial control of binding of DNA to inorganic surfaces with a view to patterning high densities arrays.

Billingsley, D. J.; Lee, A. J.; Johansson, N. A. B.; Walton, A.; Stanger, L.; Crampton, N.; Bonass, W. A.; Thomson, N. H.

2014-01-01

379

Nuclear quantum effects in water exchange around lithium and fluoride ions  

E-print Network

We employ classical and ring polymer molecular dynamics simulations to study the effect of nuclear quantum fluctuations on the structure and the water exchange dynamics of aqueous solutions of lithium and fluoride ions. While we obtain reasonably good agreement with experimental data for solutions of lithium by augmenting the Coulombic interactions between the ion and the water molecules with a standard Lennard-Jones ion-oxygen potential, the same is not true for solutions of fluoride, for which we find that a potential with a softer repulsive wall gives much better agreement. A small degree of destabilization of the first hydration shell is found in quantum simulations of both ions when compared with classical simulations, with the shell becoming less sharply defined and the mean residence time of the water molecules in the shell decreasing. In line with these modest differences, we find that the mechanisms of the exchange processes are unaffected by quantization, so a classical description of these reaction...

Wilkins, David M; Dang, Liem X

2015-01-01

380

Effect of formaldehyde on Cu(II) removal from synthetic complexed solutions by ion exchange.  

PubMed

The effect of formaldehyde (HCHO) on the ion exchange of Cu(II) from an equimolar EDTA (ethylenediaminetetraacetic acid, H(4)L) solution with a strong-base Amberlite IRA-400 resin was studied. Experiments were conducted as a function of the initial concentration of Cu(II) (0.5-10 mM), solution pH (1.0-6.0), HCHO concentration (0-6 vol%), and temperature (15-35 degrees C). It was shown that the amount of exchange of Cu(II), which exists in the form of complexed anions CuL(2-), increased with increasing solution pH and reached a plateau at an equilibrium pH (pH(e)) of 3.5. However, the amount of exchange decreased with increasing HCHO concentration up to 3 vol% but then slightly decreased with a further increase in HCHO concentration. Such effect of added HCHO was determined by the following two factors: the competitive exchange of HCOO(-) anions and the enhanced exchange of Cu(I) in the form of complexed anions CuL(3-). The exchange isotherm obtained at a fixed pH(e) could be well described by the Langmuir equation. The isosteric enthalpy change for the present ion exchange process was also evaluated and discussed. PMID:15857647

Juang, Ruey-Shin; Lin, Su-Hsia; Kao, Hsiang-Chien; Theng, Ming-Huei

2005-06-01

381

Framework for correlating composition dependent equilibrium conversion in methyl tert-butyl ether formation by ion-exchange catalysts  

SciTech Connect

Catalyst performance for the reaction of methanol and isobutylene (IB) to form methyl tert-butyl ether can be assessed based on maximum conversion. The equilibrium conversion attainable for this reaction is of practical interest since separation of products from reactants downstream of the reactor can be simplified as the extent of conversion increases. A framework is presented by which different catalysts can be compared on an internally consistent basis for different temperatures, isobutylene concentrations, and/or methanol/isobutylene mole ratios. An equilibrium expression which accounts for the presence of nonreacting components is presented to correlate the effect of methanol/IB ratios and IB concentrations with observed conversions for different catalysts. Assumptions inherent in this method are discussed and data for several types of ion-exchange catalysts illustrate use of this framework.

Ladisch, M.; Westgate, P.; Hendrickson, R.; Brewer, M. [Purdue Univ., West Lafayette, IN (United States)

1995-08-01

382

Systemic acid load from the diet affects maximal exercise respiratory exchange ratio  

PubMed Central

Background A maximal exercise respiratory exchange ratio (RERmax) ?1.10 is commonly used as a criterion to determine if a “true” maximal oxygen uptake (VO2max) has been attained during maximal-effort exercise testing. Because RERmax is heavily influenced by CO2 production from acid buffering during maximal exercise, we postulated that dietary acid load, which affects acid-base regulation, might contribute to variability in RERmax. Purpose To determine if a habitual dietary intake that promotes systemic alkalinity results in higher RERmax during VO2max testing. Methods Sedentary men and women (47-63y, n=57) with no evidence of cardiovascular disease underwent maximal graded treadmill exercise tests. VO2max and RERmax were measured with indirect calorimetry. Habitual diet was assessed for its long-term effect on systemic acid-base status by performing nutrient analysis of food diaries and using this information to calculate the potential renal acid load (PRAL). Participants were grouped into tertiles based on PRAL. Results The lowest PRAL tertile (alkaline PRAL) had higher RERmax values (1.21±0.01, p?0.05) than the middle tertile (1.17±0.01) and highest PRAL tertile (1.15±0.01). There were no significant differences (all p?0.30) among PRAL tertiles for RER at submaximal exercise intensities of 70%, 80%, or 90% VO2max. After controlling for age, sex, VO2max, and maximal heart rate (HRmax), regression analysis demonstrated that 19% of the variability in RERmax was attributed to PRAL (r=?0.43, p=0.001). Unexpectedly, HRmax was lower (p?0.05) in the low PRAL tertile (164±3 beats/min) versus the highest PRAL tertile (173±3 beats/min). Conclusion These results suggest that individuals on a diet that promotes systemic alkalinity may more easily achieve the RERmax criterion of ?1.10 which might lead to false-positive conclusions about achieving maximal effort and VO2max during graded exercise testing. PMID:21912302

Niekamp, Katherine; Zavorsky, Gerald S.; Fontana, Luigi; McDaniel, Jennifer L; Villareal, Dennis T; Weiss, Edward P

2013-01-01

383

Antiproton-to-proton ratios for ALICE heavy-ion collisions  

NASA Astrophysics Data System (ADS)

Assuming that the final state of hadronization takes place along the freezeout line, which is defined by a constant entropy density, the antiproton-to-proton ratios produced in heavy-ion collisions are studied in framework of the hadron resonance gas (HRG) model. A phase transition from quark-gluon plasma to hadrons, a hadronization, has been conjectured in order to allow modifications in the phase-space volume and thus in the single-particle distribution function. Implementing both modifications in the grand-canonical partition function and taking into account the experimental acceptance in the heavy-ion collisions, the antiproton-to-proton ratios over center-of-mass energies ?{s} ranging from AGS to RHIC are very well reproduced by the HRG model. Comparing with the same particle ratios in pp collisions results in a gradually narrowing discrepancy with increasing ?{s}. At LHC energy, the ALICE antiproton-to-proton ratios in the pp collisions turn to be very well described by the HRG model as well. It is likely that the ALICE AA-program will produce the same antiproton-to-proton ratios as the pp-one. Furthermore, the ratio gets very close to unity indicating that the matter-antimatter asymmetry nearly vanishes. The chemical potential calculated at this energy strengthens the assumption of almost fully matter-antimatter symmetry up to the LHC energy.

Tawfik, A.

2011-06-01

384

Vacuolar cation/H exchange, ion homeostasis, and leaf  

E-print Network

to maintain turgor. As many genes encoding these antiporters have been cloned from salt-sensitive plants; e-mail eblumwald@ucdavis.edu). Summary The function of vacuolar Na /H antiporter(s) in plants has away from the cytosol, plant cells can avert ion toxicity and also utilize vacuolar Na as osmoticum

Blumwald, Eduardo

385

Sorption of beryllium from sulfate solutions by amino-carboxylic amphoteric ion-exchange resins (polyampholytes)  

SciTech Connect

In studies of sorption of beryllium ions from BeSO4 solutions by a series of aminocarboxylic polyampholytes the influence of pH and of the H2SO4, (NH4)2SO4, and BeSO4 concentrations was demonstrated. The mechanism of the process is postulated on the basis of sorption data and the results of IR-spectroscopic studies. It is concluded that carboxyl groups of polyampholytes take part in ion exchange.

Pakholkov, V.S.; Tsevin, A.P.; Rychkov, V.N.

1986-05-10

386

Ligand-Exchange Chromatography of Aromatic Amines on Resin-Bound Cobalt Ion  

Microsoft Academic Search

The use of cobalt metal for the selective separation of aromatic amines is completed with a chemically bonded diamine and glyoxime functional groups onto Lycopodium clavatum. Oximes and amines are excellent complexing agents for transition metal ions. Cobalt(II) metal ions can easily be immobilized on bis-diami-noethyl-glyoximated sporopollenin (bDAEG-sporopollenin). The ligand-exchange behavior of modified Lycopodium clavatum with respect to aromatic amines

Erol Pehlivan; Ufuk S. Vural; Ahmet Ayar; Salih Yildiz

1996-01-01

387

Self-consistent Equilibrium Model of Low-aspect-ratio Toroidal Plasma with Energetic Beam Ions  

SciTech Connect

A theoretical model is developed which allows the self-consistent inclusion of the effects of energetic beam ions in equilibrium calculations of low-aspect-ratio toroidal devices. A two-component plasma is considered, where the energetic ions are treated using a kinetic Vlasov description, while a one-fluid magnetohydrodynamic description is used to represent the thermal plasma. The model allows for an anisotropic distribution function and a large Larmor radius of the beam ions. Numerical results are obtained for neutral-beam-heated plasmas in the National Spherical Torus Experiment (NSTX). Self-consistent equilibria with an anisotropic fast-ion distribution have been calculated for NSTX. It is shown for typical experimental parameters that the contribution of the energetic neutral-beam ions to the total current can be comparable to that of the background plasma, and that the kinetic modifications of the equilibrium can be significant. The range of validity of the finite-Larmor-radius expansion and of the reduced kinetic descriptions for the beam ions in NSTX is discussed. The calculated kinetic equilibria can be used for self-consistent numerical studies of beam-ion-driven instabilities in NSTX.

E.V. Belova; N.N. Gorelenkov; C.Z. Cheng

2003-04-09

388

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

PubMed

Nutrients can be recovered from source separated human urine; however, nutrient reconcentration (i.e., volume reduction of collected urine) requires energy-intensive treatment processes, making it practically difficult to utilize human urine. In this study, energy-efficient nutrient reconcentration was demonstrated using ion exchange membranes (IEMs) in a microbial electrolysis cell (MEC) where substrate oxidation at the MEC anode provides energy for the separation of nutrient ions (e.g., NH4(+), HPO4(2-)). The rate of nutrient separation was magnified with increasing number of IEM pairs and electric voltage application (Eap). Ammonia and phosphate were reconcentrated from diluted human urine by a factor of up to 4.5 and 3.0, respectively (Eap = 1.2 V; 3-IEM pairs). The concentrating factor increased with increasing degrees of volume reduction, but it remained stationary when the volume ratio between the diluate (urine solution that is diluted in the IEM stack) and concentrate (urine solution that is reconcentrated) was 6 or greater. The energy requirement normalized by the mass of nutrient reconcentrated was 6.48 MJ/kg-N (1.80 kWh/kg-N) and 117.6 MJ/kg-P (32.7 kWh/kg-P). In addition to nutrient separation, the examined MEC reactor with three IEM pairs showed 54% removal of COD (chemical oxygen demand) in 47-hr batch operation. The high sulfate concentration in human urine resulted in substantial growth of both of acetate-oxidizing and H2-oxidizing sulfate reducing bacteria, greatly diminishing the energy recovery and Coulombic efficiency. However, the high microbial activity of sulfate reducing bacteria hardly affected the rate of nutrient reconcentration. With the capability to reconcentrate nutrients at a minimal energy consumption and simultaneous COD removal, the examined bioelectrochemical treatment method with an IEM application has a potential for practical nutrient recovery and sustainable treatment of source-separated human urine. PMID:25046373

Tice, Ryan C; Kim, Younggy

2014-11-01

389

Ratio  

NASA Astrophysics Data System (ADS)

Effects of basicity, B (CaO:SiO2 ratio) on the thermal range, concentration, and formation mechanisms of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using an in situ synchrotron X-ray diffraction-based methodology with subsequent Rietveld refinement-based quantitative phase analysis. SFCA and SFCA-I phases are the key bonding materials in iron ore sinter, and improved understanding of the effects of processing parameters such as basicity on their formation and decomposition may assist in improving efficiency of industrial iron ore sintering operations. Increasing basicity significantly increased the thermal range of SFCA-I, from 1363 K to 1533 K (1090 °C to 1260 °C) for a mixture with B = 2.48, to ~1339 K to 1535 K (1066 °C to 1262 °C) for a mixture with B = 3.96, and to ~1323 K to 1593 K (1050 °C to 1320 °C) at B = 4.94. Increasing basicity also increased the amount of SFCA-I formed, from 18 wt pct for the mixture with B = 2.48 to 25 wt pct for the B = 4.94 mixture. Higher basicity of the starting sinter mixture will, therefore, increase the amount of SFCA-I, considered to be more desirable of the two phases. Basicity did not appear to significantly influence the formation mechanism of SFCA-I. It did, however, affect the formation mechanism of SFCA, with the decomposition of SFCA-I coinciding with the formation of a significant amount of additional SFCA in the B = 2.48 and 3.96 mixtures but only a minor amount in the highest basicity mixture. In situ neutron diffraction enabled characterization of the behavior of magnetite after melting of SFCA produced a magnetite plus melt phase assemblage.

Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Studer, Andrew J.; Manuel, James R.; Kimpton, Justin A.

2014-12-01

390

Nanometer scale high-aspect-ratio trench etching at controllable angles using ballistic reactive ion etching  

SciTech Connect

We demonstrate a low pressure reactive ion etching process capable of patterning nanometer scale angled sidewalls and three dimensional structures in photoresist. At low pressure the plasma has a large dark space region where the etchant ions have very large highly-directional mean free paths. Mounting the sample entirely within this dark space allows for etching at angles relative to the cathode with minimal undercutting, resulting in high-aspect ratio nanometer scale angled features. By reversing the initial angle and performing a second etch we create three-dimensional mask profiles.

Cybart, Shane; Roediger, Peter; Ulin-Avila, Erick; Wu, Stephen; Wong, Travis; Dynes, Robert

2012-11-30

391

Charge exchange and chemical reactions with trapped thorium ions  

NASA Astrophysics Data System (ADS)

Most atomic nuclei have excitation energies ranging from keV to MeV. A unique exception is the ^229Th nucleus, which has an excited state just several eV above the nuclear ground state.ootnotetextB. R. Beck et al., Phys. Rev. Lett. 98, 142501 (2007). Th^3+ provides a convenient level structure for laser cooling in an rf Paul trap.ootnotetextC. J. Campbell et al., Phys. Rev. Lett 102, 233004 (2009). Unlike many ions commonly utilized in precision measurements, the trap lifetime of Th^3+ is limited to only several minutes. This is a severe limitation to experiments involving ^229Th as it is only available in minute quantities. Here we have studied the loss mechanisms by introduction of various contaminants and analyzed reaction products using trapped ion mass spectrometry techniques.ootnotetextL. R. Churchill et al., Phys. Rev. A 83, 012710 (2011).

Depalatis, Michael; Churchill, Layne; Chapman, Michael

2011-06-01

392

Amphoteric ion exchange membrane synthesized by radiation-induced graft copolymerization of styrene and dimethylaminoethyl methacrylate into PVDF film for vanadium redox flow battery applications  

Microsoft Academic Search

Poly(vinylidene difluoride) (PVDF) film was grafted with styrene (St) and dimethylaminoethyl methacrylate (DMAEMA) using ?-irradiation techniques. Through subsequent sulfonation and protonation processes, a new kind of amphoteric ion exchange membrane (AIEM) was synthesized. The grafting yield (GY) increased with absorbed dose and leveled off at about 60kGy. The composition of poly(St-co-DMAEMA) grafts was correlated to the ratio of St to

Jingyi Qiu; Junzhi Zhang; Jinhua Chen; Jing Peng; Ling Xu; Maolin Zhai; Jiuqiang Li; Genshuan Wei

2009-01-01

393

Degradation mechanism of sulfonated poly(ether ether ketone) (SPEEK) ion exchange membranes under vanadium flow battery medium.  

PubMed

The degradation mechanism of hydrocarbon ion exchange membranes under vanadium flow battery (VFB) medium was investigated and clarified for the first time. This work will be highly beneficial for improving the chemical stability of hydrocarbon ion exchange membranes, which is one of the most challenging issues for VFB application. PMID:25135611

Yuan, Zhizhang; Li, Xianfeng; Hu, Jinbo; Xu, Wanxing; Cao, Jingyu; Zhang, Huamin

2014-10-01

394

Pectin based cerium (IV) and thorium (IV) phosphates as novel hybrid fibrous ion exchangers synthesis, characterization and thermal behaviour  

Microsoft Academic Search

Summary Pectin based cerium (IV) and thorium (IV) phosphates have been synthesized as new phases of hybrid fibrous ion exchangers. Both materials were characterized using X-ray diffraction, infrared (IR) spectra, thermogravimetric analysis (TG), differntial thermogravimetry (DTG), differntial thermal analysis (DTA) and scanning electron microscopy (SEM), as well as the determination of their ion exchange capacity, elution and pH titration. The

K. G. Varshney; A. Agrawal; S. C. Mojumdar

2005-01-01

395

Decontamination and dismantlement of the building 594 waste ion exchange facility at Argonne National Laboratory-East project final report  

Microsoft Academic Search

The Building 594 D&D Project was directed toward the following goals: Removal of any radioactive and hazardous materials associated with the Waste Ion Exchange Facility; Decontamination of the Waste Ion Exchange Facility to unrestricted use levels; Demolition of Building 594; and Documentation of all project activities affecting quality (i.e., waste packaging, instrument calibration, audit results, and personnel exposure) These goals

Wiese

1998-01-01

396

Evaluation of Selective Ion Exchange for Nickel and Cadmium Uptake from the Rinsewaters of a Plating Shop  

Microsoft Academic Search

The use of selective ion exchange to recover metals from the rinsewaters of various plating baths has been studied. Two chelating resins possessing aminophosphonate or iminodiacetic functionalities were compared in nickel- and cadmium-bearing rinsewaters. In addition, an inorganic ion exchanger based on sodium titanate was studied against nickel containing rinsewaters. Breakthrough capacities of 5% and decontamination factors were calculated from

TUOMO H. KARPPINEN; ARTO YLI-PENTTI

2000-01-01

397

Dissociative recombination of water cluster ions with free electrons: cross sections and branching ratios.  

PubMed

Dissociative recombination (DR) of water cluster ions H(+)(H(2)O)(n) (n=4-6) with free electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). For the first time, branching ratios have been determined for the dominating product channels and absolute DR cross sections have been measured in the energy range from 0.001 to 0.7 eV. Dissociative recombination is concluded to result in extensive fragmentation for all three cluster ions, and a maximum number of heavy oxygen-containing fragments is produced with a probability close to unity. The branching ratio results agree with earlier DR studies of smaller water cluster ions where the channel nH(2)O+H has been observed to dominate and where energy transfer to internal degrees of freedom has been concluded to be highly efficient. The absolute DR cross sections for H(+)(H(2)O)(n) (n=4-6) decrease monotonically with increasing energy with an energy dependence close to E(-1) in the lower part of the energy range and a faster falloff at higher energies, in agreement with the behavior of other studied heavy ions. The cross section data have been used to calculate DR rate coefficients in the temperature range of 10-2000 K. The results from storage ring experiments with water cluster ions are concluded to partly confirm the earlier results from afterglow experiments. The DR rate coefficients for H(+)(H(2)O)(n) (n=1-6) are in general somewhat lower than reported from afterglow experiments. The rate coefficient tends to increase with increasing cluster size, but not in the monotonic way that has been reported from afterglow experiments. The needs for further experimental studies and for theoretical models that can be used to predict the DR rate of polyatomic ions are discussed. PMID:18247953

Ojekull, J; Andersson, P U; Pettersson, J B C; Markovi?, N; Thomas, R D; Al Khalili, A; Ehlerding, A; Osterdahl, F; af Ugglas, M; Larsson, M; Danared, H; Källberg, A

2008-01-28

398

Development of a Waste Water Regenerative System - Using Sphagnum Moss Ion-exchange  

NASA Astrophysics Data System (ADS)

The use of inexpensive, light weight and regenerative systems in an enclosed environment is of great importance to sustained existence in such habitats as the International Space Station, Moon or even Mars. Many systems exist which utilise various synthetic ion exchangers to complete the process of waste water clean-up. These systems do have a very good exchange rate for cations but a very low exchange rate for anions. They also have a maximum capacity before they need regeneration. This research proposes a natural alternative to these synthetic ion-exchangers that utilises one of natures greatest ion-exchangers, that of Sphagnum Moss. Sphagna can be predominantly found in the nutrient poor environment of Raised Bogs, a type of isolated wetland with characteristic low pH and little interaction with the surrounding water table. All nutrients come from precipitation. The sphagna have developed as the bog's sponges, soaking up all available nutrients (both cation & anion) from the precipitation and eventually distributing them to the surrounding flora and fauna, through the water. The goal of this research is to use this ability in the processing of waste water from systems similar to isolated microgravity environments, to produce clean water for reuse in these environments. The nutrients taken up by the sphagna will also be utilised as a growth medium for cultivar growth, such as those selected for hydroponics' systems.

McKeon, M.; Wheeler, R.; Leahy, Jj

399

Conversion of pollutants to fertilisers: ion exchange synthesis of potassium sulphate from acidic mine waters.  

PubMed

The paper reports the results obtained by the development of ion exchange synthesis of K2SO4 from the natural acidic mine waters (AMW) of Rio Tinto area (Huelva, Spain). The process flowsheet includes several sequential stages permitting production of potassium sulphate and desalinated water along with the recovery of four metals. PMID:12926638

Muraviev, D

2003-01-01

400

WASTEWATER DEMINERALIZATION BY TWO-STAGE FIXED-BED ION EXCHANGE PROCESS  

EPA Science Inventory

A 9.5 l/min (2.5 gpm) two-stage fixed bed ion exchange process (primary cation - primary anion - secondary cation - secondary anion) was operated on a feed of carbon treated secondary effluent for 48 months at Pomona, California. To achieve high levels of regeneration efficiency ...

401

KINETIC ASPECTS OF THE ION EXCHANGE EXTRACTION OF GOLD, SILVER, AND BASE METAL CYANO COMPLEXES  

Microsoft Academic Search

The simultaneous ion exchange extraction of selected pairs of noble and base metal cyano complexes was studied. In most cases It was found that equilibrium Is attained only after a period of several hours during which time the resin composition undergoes marked variations. As a rule, the loading of noble metals passes through a maximum value while the loading of

P. A. Riveros; W. Charles Cooper

1988-01-01

402

ONE MGD ION EXCHANGE PLANT FOR REMOVAL OF NITRATE FROM WELL WATER  

EPA Science Inventory

A full scale 1 mgd demonstration plant, using ion exchange, for removal of nitrate from well water was built at McFarland, California. The plant has been performing satisfactorily in the semi-automatic mode since October 1983. Full automation of the plant was completed in June 19...

403

Spent ion exchange resin-its treatment from the point of view of safe disposal.  

PubMed

Ion exchange process is one of the treatment methods for radioactive waste. The resin becomes no longer useful after number of cycles of usage. At the same time the regenerated resin cannot be considered as non active waste for disposal. Hence it is felt necessary that the regenerated resin is treated in a fashion so as to result in a form which can be considered as inactive material. It is possible to convert this spent resin into multivalent ionic form which are generally non leachable, thus providing the necessary properties for meeting the disposal criteria. Studies were carried out for the exchange of radioactive ions on these resins with ions like Al3+, Sn4+, Pb2+ and Fe3+ etc. The studies included leachability aspects, exchange with other active ions, thermal characteristics, compressive strength of the cement blocks loaded with the resin etc. Our studies indicated that the order of the stability of the resin with respect to properties like leachability, exchange properties etc. follow the trend as follows: Sn4+ > Pb2+ > Al3+ > Fe3+. PMID:14723279

Seshadri, K S; Raj, S S; Lal, K B

2003-01-01

404

ARSENIC REMOVAL BY FULL SCALE ION EXCHANGE AND ACTIVATED ALUMINA TREATMENT  

EPA Science Inventory

This presentation discusses the results of a one year performance evaluation study of two ion exchange plants and two activated alumina plants that were designed and operated for the removal of arsenic from well water. All the plants were shown to be capable of reducing arsenic l...

405

ARSENIC REMOVAL FROM DRINKING WATER BY ION EXCHANGE AND ACTIVATED ALUMINA PLANTS  

EPA Science Inventory

This report documents a long term performance study of two ion exchange (IE) and two activated alumina (AA) treatment plants to remove arsenic from drinking water. Performance information was collected on these systems that are located in the northeast for one full year. The stud...

406

Synthesis of Anomeric Methyl Fructofuranosides and Their Separation on an Ion-Exchange Resin  

ERIC Educational Resources Information Center

Treatment of d-fructose with methanol in the presence of acid as a catalyst gives a mixture of methyl-[beta]-d-fructopyranoside, methyl-[alpha]-D-fructofuranoside, and methyl-[beta]-d-fructofuranoside, which were separated on an ion exchange column and characterized polarimetrically.

Nurminen, Erkki; Poijarvi, Paivi; Koskua, Katja; Hovinen, Jari

2007-01-01

407

SUMMARY REPORT: CONTROL AND TREATMENT TECHNOLOGY FOR THE METAL FINISHING INDUSTRY: ION EXCHANGE  

EPA Science Inventory

This Technology Transfer ummary Report is one of a series of reports that summarizes a pollution control technology for the metal finishing industry. he 45-page report is intended to promote an understanding of the use of ion exchange in the metal finishing industry. The sections...

408

Extraction of phosphorus, potassium, calcium, and magnesium from soils by an ion?exchange resin procedure  

Microsoft Academic Search

A procedure for the simultaneous extraction of phosphorus, potassium, calcium and magnesium from soils, by an ion?exchange resin procedure applicable to large?scale advisory soil testing, is described. The important steps are the disaggregation of soil by shaking in water during 15 minutes with a glass marble, the transference of the elements from the soil to a sodium bicarbonate treated mixture

B. van Raij; J. A. Quaggio; N. M. da Silva

1986-01-01

409

Improvement of technology for treatment of spent radioactive ion-exchange resins at nuclear power stations  

NASA Astrophysics Data System (ADS)

Results from tests of technology for decontaminating spent radioactive ion-exchange resins at the Balakovo and Kalinin nuclear power stations are presented. Versions of technological schemes with cleaning and repeated use of decontaminating solution are considered. The possibility of considerably reducing the volume of radioactive wastes is demonstrated.

Korchagin, Yu. P.; Aref'ev, E. K.; Korchagin, E. Yu.

2010-07-01

410

Water transport study across commercial ion exchange membranes in the vanadium redox flow battery  

Microsoft Academic Search

The water transfer behaviour of Selemion CMV, AMV and DMV membranes (Asahi Glass, Japan) has been studied in the vanadium redox cell, as was the water transfer across Nafion 117 membrane (E.I. Du Pont, USA). The earlier water transport studies of a variety of commercial ion exchange membranes and non-ionic separators in the vanadium redox cell have shown that the

T. Mohammadi; S. C. Chieng; M. Skyllas Kazacos

1997-01-01

411

Metal ions exchanged montmorillonite as catalyst for alkylation of benzene with 1-dodecene  

Microsoft Academic Search

Summary  About 8.5% of benzene was alkylated with 1-dodecene in the presence of Na+-montmorillonite. When the reaction was carried out with montmorillonite exchanged with Mn2+, Cu2+, Ni2+, Zn2+ and Fe2+ ions as catalyst (M2+\\/mont.), 91 to 95% of 1-dodecene was remarkably converted to a mixture of linear monoalkylbenzenes.

Firouzeh Zarkesh; Faezeh Farzaneh; Mehdi Ghandi

2006-01-01

412

The effect of some transition metal ions exchanged with zeolites on benzaldehyde, benozophenone and cyclohexanone phenylhydrazones  

Microsoft Academic Search

Phenylhydrazone derivatives of benzaldehyde, benzophenone and cyclohexanone under the catalytic effect of exchanged zeolite NaY (NaA and HS in some cases) with transition metal ions of chromium (III), iron (III), manganese (II), nickel (II) and copper (II) in refluxing benzene resulted in the formation of benzaldehyde, benzophenone and cyclohexanone respectively, Side products like benzonitrile and biphenyl were also identified.

F. Farzaneh; J. Soleimannejad; M. Ghandi

1997-01-01

413

Exchange and polarization effects on elastic electron-atom/ion scattering  

E-print Network

Exchange and polarization effects on elastic electron-atom/ion scattering (aka. a small part approaches Needed for modeling and simulations : · accurate atomic and molecular data (, d/d, , rates physics · atomic physics · molecular physics · beam-surface interactions #12;0 ( ) ( ) ( ) ( ) e e e i i i

Kaganovich, Igor

414

ANNUAL REPORT. NEW METAL NIOBATE AND SILICOTITANATE ION EXCHANGERS: DEVELOPMENT AND CHARACTERIZATION  

EPA Science Inventory

This project focuses on the synthesis and characterization of silicotitanate- and niobate-based ion exchangers for Cs and Sr removal and their related condensed phases as potential ceramic waste forms, as well as on understanding the structural property relationship and thermodyn...

415

Ion exchange resins. (Latest citations from the NTIS Bibliographic database). Published Search  

SciTech Connect

The bibliography contains citations concerning the preparation and applications of ion exchange resins. Their uses as catalysts and in treatment of water and wastes, chemical analysis and reactions, nuclear fuels and reactors, and in various recovery, purification, and separation processes are discussed. Performance evaluations are also included relative to air purification processes. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1993-11-01

416

Ion exchange resins. (Latest citations from the NTIS bibliographic database). Published Search  

SciTech Connect

The bibliography contains citations concerning the preparation and applications of ion exchange resins. Their uses as catalysts and in treatment of water and wastes, chemical analysis and reactions, nuclear fuels and reactors, and in various recovery, purification, and separation processes are discussed. Performance evaluations are also included relative to air purification processes. (Contains 250 citations and includes a subject term index and title list.)

NONE

1995-01-01

417

Ion Exchange Separation of the Antitumor Component(s) of Yogurt Dialyzate1  

Microsoft Academic Search

The active antitumor component of yogurt obtained by dialysis was further fractionated by ion exchange chro- matography into acidic, basic, and neutral fractions, which were analyzed for activity by in vitro agar diffusion, cell culture, and in vivo mouse assay. Neither dialysate nor fractions showed any antitumor activity when tested by agar diffusion or cell culture techniques. When tested by

A. D. Ayebo; K. M. Shahani; R. Dam; B. A. Friend

1982-01-01

418

Processing-property relationship in ion-exchanged ESP (engineered stress profile) glasses  

Microsoft Academic Search

A novel two-step ion exchange process was recently proposed to produce Engineered Stress Profile (ESP) glass. Important characteristics of ESP glass include high strength, relatively low strength variability and high surface damage resistance. It has been found that the mechanical reliability of ESP glass is mainly dependent on the processing conditions. Therefore, the primary objective of the current thesis is

Junwu Shen

2003-01-01

419

Boron removal from industrial wastewaters by ion exchange: an analytical control parameter  

Microsoft Academic Search

The results obtained from the application of molecular absorption spectrophotometry using Azomethine H to establish breakthrough curves for the boron purification process are presented in order to determine the breakthrough point, or maximum acceptable effluent concentration, which is regulated by environmental legislation. The breakthrough capacity of the ion-exchange process and the degree of column utilisation were also calculated. The results

Ma del Mar de la Fuente García-Soto; Eugenio Muñoz Camacho

2005-01-01

420

Ag clustering investigation in laser irradiated ion-exchanged glasses by optical and vibrational spectroscopy  

NASA Astrophysics Data System (ADS)

Ion exchange process is widely used to dope silicate glass layers with silver for several applications, ranging from light waveguide to nanostructured composite glass fabrication. The silver-doped structure and its physical properties depend on the preparation parameters as well as on subsequent treatments. In particular, laser irradiation of the ion exchanged glasses has been demonstrated to be an effective tool to control cluster size and size distribution. Nevertheless, a complete comprehension of the basic phenomena and a systematic characterization of these systems are still lacking. In this paper, an extended optical characterization is presented for soda-lime glass slides, doped with silver by Ag+-Na+ ion exchange, thermally treated and irradiated with a Nd:YAG laser beam at different wavelengths, and for different energy density. The samples were characterized by various spectroscopic techniques, namely, optical absorption, photoluminescence and micro-Raman analysis. The availability of all these characterization techniques allowed pointing out a suitable scenario for the Ag clustering evolution as a function of the ion exchange, annealing and laser irradiation parameters.

Trave, E.; Cattaruzza, E.; Gonella, F.; Calvelli, P.; Quaranta, A.; Rahman, A.; Mariotto, G.

2012-09-01

421

Net gain demonstration with glass hybrid optical amplifiers made by ion-exchange and wafer bonding  

NASA Astrophysics Data System (ADS)

Thanks to the maturing of rare-earth highly-doped materials, erbium-doped waveguide amplifiers (EDWAs) present a compact alternative to fiber amplifiers. While ion-exchanged EDWAs implemented on glass substrates provide the best passive characteristics, EDWAs based on thin films technologies offer a higher integration and amplification efficiencies. This paper proposes the realization of EDWAs in a new configuration which combines all these advantages. Indeed, this optical amplifier consists of an erbium/ytterbium-codoped glass guiding layer reported on an ion-exchanged strip formed on a passive glass substrate. The electromagnetic principle of operation of this hybrid structure is presented as well as simulations of its behaviour. Then, the realization and characterization of two different hybrid amplifiers is presented: the first one, based on a Tl +/K + ion-exchanged strip provides a high gain coefficient of 3.66 +/- 0.25 dB/cm; whereas the second one, realized with a Ag +/Na + ion-exchanged strip, presents a good coupling efficiency with optical fibers, which allows the measurement of a 1 dB net gain.

Gardillou, Florent; Broquin, Jean-Emmanuel

2006-02-01

422

Buried ion-exchanged glass waveguides featuring low birefringence with a broad range of waveguide widths  

NASA Astrophysics Data System (ADS)

Optical communications networks require integrated photonic components with negligible polarization dependence, which typically means that the waveguides must feature very low birefringence. Recent studies have shown that waveguides with low birefringence can be obtained, e.g., by using silica on Si waveguides and by buried ion-exchanged glass waveguides. However, many integrated photonic circuits consist of waveguides with varying widths. Therefore, low birefringence is consequently required for waveguides having different widths. This is a difficult task for most waveguide fabrication technologies. In this paper we present theoretical and experimental results on waveguide birefringence for buried silver ion-exchanged glass waveguides. We show that the waveguide birefringence is on the order of 10-6 for waveguide mask opening widths ranging from 2 to 9 ?m. The measured values are in good agreement with the values calculated with our modeling software for ion-exchanged glass waveguides. This unique feature of ion-exchanged waveguides may be of significant importance in a wide variety of integrated photonic circuits requiring polarization independent operation.

Yliniemi, Sanna E.; West, Brian R.; Aalto, Timo T.; Madasamy, Pratheepan; Peyghambarian, Nasser; Honkanen, Seppo

2004-08-01

423

Ion-exchanged glass waveguides with low birefringence for a broad range of waveguide widths  

NASA Astrophysics Data System (ADS)

Optical communications networks require integrated photonic components with negligible polarization dependence, which typically means that the waveguides must feature very low birefringence. Recent studies have shown that waveguides with low birefringence can be obtained, e.g., by use of silica-on-silicon waveguides or buried ion-exchanged glass waveguides. However, many integrated photonic circuits consist of waveguides with varying widths. Therefore low birefringence is consequently required for waveguides having different widths. This is a difficult task for most waveguide fabrication technologies. We present experimental results on waveguide birefringence for buried silver-sodium ion-exchanged glass waveguides. We show that the waveguide birefringence of the order of 10^-6 for waveguide mask opening widths ranging from 2 to 10 ?m can be obtained by postprocessing the sample through annealing at an elevated temperature. The measured values are in agreement with the values calculated with our modeling software for ion-exchanged glass waveguides. This unique feature of ion-exchanged waveguides may be of significant importance in a wide variety of integrated photonic circuits requiring polarization-independent operation.

Yliniemi, Sanna; West, Brian R.; Honkanen, Seppo

2005-06-01

424

Journal of Membrane Science 239 (2004) 1726 Highly conductive ordered heterogeneous ion-exchange membranes  

E-print Network

conductivity, swelling properties, ion-exchange capacity and permselectivity is studied. The advantages types are often reinforced with a net of polymeric material, such as polyamide or polyester this range results in a loss of membrane strength and in reduced shape stability, due to increased swelling

Freger, Viatcheslav "Slava"

425

Surfactant-Mediated Ion Exchange and Charge Reversal at Ionic Liquid Interfaces Lang G. Chen,  

E-print Network

Surfactant-Mediated Ion Exchange and Charge Reversal at Ionic Liquid Interfaces Lang G. Chen for numerous applications. Here, we show that the combination of charged surfactants with ILs leads to rich][MeSO3]. XPS also reveals that surfactant counterions readily dissociate into the bulk, which when

426

Development and testing of ion exchangers for treatment of liquid wastes at Oak Ridge National Laboratory  

SciTech Connect

This report addresses three areas of waste treatment: (1) treatment of newly generated low-level liquid waste and Melton Valley Storage Tank (MVST) supernate using inorganic ion exchangers; (2) treatment of processing streams at the Radiochemical Engineering Development Center (REDC); and (3) removal of radionuclides from organic solutions. Distribution of various radionuclides between simulated waste solutions and several sorbents was determined in batch tests. Inorganic ion exchangers were prepared in the form of microspheres by an intemal gelation process. Microspheres of hydrous titania, hydrous zirconia, hydrous titania containing embedded sodium cobalt hexacyanoferrate, and the corresponding phosphate forms of these materials were prepared. Several zeolites (PDZ-140, PDZ-300, EE-96, CBV-10A) and inorganic ion exchangers (hydrous titania, hydrous zirconia, polyantimanic acid, sodium cobalt hexacyanoferrate) were tested for the removal of cesium and strontium from the acidic simulated Cleanex raffinate generated at REDC. A resorcinol-based ion-exchange resin and three types of sodium titanate were tested for removal of cesium and strontium from the REDC caustic dissolver solution. Hydrous titania, hydrous zirconia, and their corresponding phosphates were tested for the removal of Eu[sup 3+] from various solutions of di-2-ethylbexyl phosphoric acid (HDEHP) in toluene or dodecane.

Collins, J.L.; Davidson, D.J.; Chase, C.W.; Egan, B.Z. (Oak Ridge National Lab., TN (United States)); Ensor, D.D.; Bright, R.M.; Glasgow, D.C. (Tennessee Technological Univ., Cookeville, TN (United States))

1993-03-01

427

Development and testing of ion exchangers for treatment of liquid wastes at Oak Ridge National Laboratory  

SciTech Connect

This report addresses three areas of waste treatment: (1) treatment of newly generated low-level liquid waste and Melton Valley Storage Tank (MVST) supernate using inorganic ion exchangers; (2) treatment of processing streams at the Radiochemical Engineering Development Center (REDC); and (3) removal of radionuclides from organic solutions. Distribution of various radionuclides between simulated waste solutions and several sorbents was determined in batch tests. Inorganic ion exchangers were prepared in the form of microspheres by an intemal gelation process. Microspheres of hydrous titania, hydrous zirconia, hydrous titania containing embedded sodium cobalt hexacyanoferrate, and the corresponding phosphate forms of these materials were prepared. Several zeolites (PDZ-140, PDZ-300, EE-96, CBV-10A) and inorganic ion exchangers (hydrous titania, hydrous zirconia, polyantimanic acid, sodium cobalt hexacyanoferrate) were tested for the removal of cesium and strontium from the acidic simulated Cleanex raffinate generated at REDC. A resorcinol-based ion-exchange resin and three types of sodium titanate were tested for removal of cesium and strontium from the REDC caustic dissolver solution. Hydrous titania, hydrous zirconia, and their corresponding phosphates were tested for the removal of Eu{sup 3+} from various solutions of di-2-ethylbexyl phosphoric acid (HDEHP) in toluene or dodecane.

Collins, J.L.; Davidson, D.J.; Chase, C.W.; Egan, B.Z. [Oak Ridge National Lab., TN (United States); Ensor, D.D.; Bright, R.M.; Glasgow, D.C. [Tennessee Technological Univ., Cookeville, TN (United States)

1993-03-01

428

Treatment of acid mine water by use of heavy metal precipitation and ion exchange  

Microsoft Academic Search

Acid mine water from a South African gold mine was characterised and treated by the precipitation of heavy metals with lime and sulphides, followed by ion exchange. The novelty of the proposed process lies in the use of carrier magnetic materials for more effective separation of water and solids, as well as the oxidation pretreatment that is also used to

D. Feng; C. Aldrich; H. Tan

2000-01-01

429

Removing Radium-226 Contamination From Ion Exchange Resins Used in Drinking Water Treatment  

E-print Network

Removing Radium-226 Contamination From Ion Exchange Resins Used in Drinking Water Treatment P r o b to remove naturally occurring radioactivity in groundwater limits the effectiveness to treat to drinking removal process during cleaning of resins with varying age and total cleaning cycles. M e t h o d o l o g

430

Basis document for PFP plutonium nitrate ion exchange process in Room 228A  

SciTech Connect

The PFP facility currently has approximately 4300 liters of plutonium nitrate solution in storage. This material will be calcined by the Vertical Denigration Calciner (VDC) located in room 230C. However, part of the material needs to be purified to remove constituents that will interfere with the calcination process. An Ion Exchange process using Reillex{trademark} HPQ anion exchange resin was tested by the Plutonium Process Support Laboratories (PPSL) (I). The Ion exchange process is to be installed in glovebox HC-7 in room 228A/234-5Z. The plutonium separated from the interfering constituents will be in a concentrated condition ready to be calcined by the VDC in room 230C. The oxide product of the VDC will be placed into the 2736-Z vaults for long term storage.

Risenmay, H.R.

1997-04-23

431

Ion-to-CH3 flux ratio in diamond chemical-vapor deposition  

NASA Astrophysics Data System (ADS)

Methyl radicals (CH3) and positive ionic species in a low-pressure inductively coupled plasma under diamond-depositing conditions have been detected by using a quadrupole mass spectrometer. Absolute calibration of the fluxes of CH3 and ionic species was made by the threshold ionization technique and Langmuir probe measurement, respectively. The CH3 density increased by two to three times with a small addition of carbon monoxide to a methane-hydrogen plasma and was on the order of 1011-1012 cm-3. As the pressure decreased from 60 to 10 mTorr, the ion-to-CH3 flux ratio increased from 0.2 to 4.3, accompanied by an increase in the fraction of light ions such as Hx+ (x=1-3). The average ion energy in the ion energy distribution at a grounded electrode was compared with the sheath potential and the discrepancy was found to be 0.5-2 eV depending on pressure and ion mass. The results were used to describe the specific surface process dominated by energetic (˜ several eV) ions rather than thermal neutrals.

Teii, Kungen; Hori, Masaru; Goto, Toshio

2002-10-01

432

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

NASA Technical Reports Server (NTRS)

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.

Tanner, Stephen P.

1997-01-01

433

Comparison of ion exchange and cw CO2 laser treatment of Nd-doped phosphate laser glass  

NASA Astrophysics Data System (ADS)

In recent years, the effect of laser pre-irradiation and ion exchange on glasses surface were widely carried out to stabilize their damage thresholds. But comparison of ion exchange and CW CO2 laser treatment is never studied, this paper is devoted to the investigation of this question. Nd-doped phosphate laser glasses were heated with CW CO2 laser radiation and were strengthened by ion exchange. Laser damage thresholds of the surface were measured with 1064 nm 10 ns pulses focused to small spots irradiation. Both ion exchange treatment and CW CO2 laser treatment result in residual compress stress occurred at surface, peak-to- volley and microcracks decreased in surface appearance, and damage thresholds of surfaces increased by a factor of over 2. Polariscope, reflected optical microscope and atomic force microscope are used for stress, damage morphologies and surface topography analysis on glass surface. It is shown that laser condition mechanism is consistent with ion exchange treatment mechanism.

Hui, Gong; Chengfu, Li

1996-05-01

434

Continuous separation of carbohydrates by ion-exchange chromatography  

SciTech Connect

A synthetic mixture of fructose, mannitol and sorbitol was continuously separated by a chromatographic method using a cation-exchange resin (Dowex 50W-X8) in its Ca{sup 2+}-form as the stationary phase. An annular chromatograph (AC) was used to achieve a continuous mode of operation. Distribution and mass transfer coefficients of the three substances as well as bed properties were obtained by batch chromatography. The separation was simulated mathematically in terms of an approximate linear chromatographic theory was applied to the modeling of the behavior of the continuous separations. The influence of rotation rate, column loading, eluent flow rate and feed concentration on the resolution of the individual peaks were investigated.

Wolfgang, J.; Prior, A. [Prior Technology, Goetzis (Australia); Bart, H.J.; Messenboeck, R.C. [Univ. Kaiserslautern (Germany); Byers, C.H. [Oak Ridge National Lab., TN (United States)

1997-01-01

435

Intensity ratio of EUV emission lines in Fe XV studied with electron beam ion traps  

NASA Astrophysics Data System (ADS)

We present emission spectra of highly charged Fe ions in the extreme ultraviolet range obtained with two electron beam ion traps. The intensity ratio between the 3s3p3P2 - 3s3d 3D3 (233.9 Å) and 3s3p 1P1 - 3s3d 1D2 (243.8 Å) transitions in Fe XV is given for various electron beam parameters. The experimental ratios are compared with theoretical model calculation as well as our previous experiment, where significant discrepancy with theoretical model was found. The present result, which has been obtained with a higher resolution spectrometer to investigate possible line blending, confirms that the discrepancy is not due to line blending.

Shimizu, Erina; Sakaue, Hiroyuki A.; Kato, Daiji; Murakami, Izumi; Yamamoto, Norimasa; Hara, Hirohisa; Watanabe, Tetsuya; Nakamura, Nobuyuki

2015-01-01

436

Transport, charge exchange and loss of energetic heavy ions in the earth's radiation belts - Applicability and limitations of theory  

NASA Technical Reports Server (NTRS)

Computer simulations of processes which control the relative abundances of ions in the trapping regions of geospace are compared with observations from discriminating ion detectors. Energy losses due to Coulomb collisions between ions and exospheric neutrals are considered, along with charge exchange losses and internal charge exchanges. The time evolution of energetic ion fluxes of equatorially mirroring ions under radial diffusion is modelled to include geomagnetic and geoelectric fluctutations. Limits to the validity of diffusion transport theory are discussed, and the simulation is noted to contain provisions for six ionic charge states and the source effect on the radiation belt oxygen ion distributions. Comparisons are made with ion flux data gathered on Explorer 45 and ISEE-1 spacecraft and results indicate that internal charge exchanges cause the radiation belt ion charge state to be independent of source charge rate characteristics, and relative charge state distribution is independent of the radially diffusive transport rate below the charge state redistribution zone.

Spjeldvik, W. N.

1981-01-01

437

Refractive index profile and its guided mode characteristics of ion-exchanged planar optical waveguides  

NASA Astrophysics Data System (ADS)

The refractive index profile and the propagation characteristics of guided beam mode for planar optical waveguides fabricated with ion exchange from molten salts of silver nitrate are discussed. The pyrex glass substrate was dipped into an AgNO3 melt for a typical 3 to 9 hours at 300 C of diffusion temperature; some alkali ions are exchanged by Ag(+) ions forming a high index at the surface. The index profiles are determined by the inverse W.K.B. method based on mode spectroscopy and shown to be exponentially decreasing from the surface. The mode functions are obtained by solving the wave equation for an exponential profile and shown graphically in order to have some understanding of the mechanism producing a scattering loss. The attenuation of the sample waveguides fabricated is also measured and yields a beam loss of 2.0 to 2.5 dB/cm for TE sub 0 mode excitation. Measurements of mode conversion, mode and thickness dependent losses of the waveguide are discussed in detail. These results allow identification of the loss mechanism which depends on either the surface roughness or silver ion concentration in an ion exchanged planar optical waveguide.

Haneda, N.; Imal, M.; Ohtsuka, Y.

1983-07-01

438

Enrichment factor, height of separation unit, and separation efficiency by ion exchange with chemical reaction  

SciTech Connect

The enrichment factor ({epsilon}{sub u}) in the separation unit of ion-exchange and chemical reactions is a function of the enrichment factor of the chemical reaction ({epsilon}{sub r,s}) and the {open_quotes}equilibrium coefficients{close_quotes} ({zeta}) which are determined only by the distribution of the ions in both the solution and ion-exchange phases. The factor can be simply expressed as {epsilon}{sub u}={zeta}{epsilon}{sub r,s}. The height of the separation unit is the sum of heights due to ion exchange, chemical reaction, and flow pattern. The height is also due to the {open_quotes}kinetics coefficient{close_quotes} {zeta}, which is a function of the distribution as well as the {open_quotes}equilibrium coefficient.{close_quotes} The separation efficiency is proportional to {zeta}/{radical}v, both of which depend on the concentration of ions in the unit. Several schemes for the separation units are also discussed.

Takeda, Kunihiko; Morita, Keiichiro [Shibaura Inst. of Technology, Tokyo (Japan)

1996-11-01

439

Contact Activation of Blood Plasma and Factor XII by Ion-exchange Resins  

PubMed Central

Sepharose ion-exchange particles bearing strong Lewis acid/base functional groups (sulfopropyl, carboxymethyl, quarternary ammonium, dimethyl aminoethyl, and iminodiacetic acid) exhibiting high plasma protein adsorbent capacities are shown to be more efficient activators of blood factor XII in neat-buffer solution than either hydrophilic clean-glass particles or hydrophobic octyl sepharose particles ( FXII?surfaceactivatorFXIIa; a.k.a autoactivation, where FXII is the zymogen and FXIIa is a procoagulant protease). In sharp contrast to the clean-glass standard of comparison, ion-exchange activators are shown to be inefficient activators of blood plasma coagulation. These contrasting activation properties are proposed to be due to the moderating effect of plasma-protein adsorption on plasma coagulation. Efficient adsorption of blood plasma proteins unrelated to the coagulation cascade impedes FXII contacts with ion-exchange particles immersed in plasma, reducing autoactivation, and causing sluggish plasma coagulation. By contrast, plasma proteins do not adsorb to hydrophilic clean glass and efficient autoactivation leads directly to efficient activation of plasma coagulation. It is also shown that competitive-protein adsorption can displace FXIIa adsorbed to the surface of ion-exchange resins. As a consequence of highly-efficient autoactivation and FXIIa displacement by plasma proteins, ion-exchange particles are slightly more efficient activators of plasma coagulation than hydrophobic octyl sepharose particles that do not bear strong Lewis acid/base surface functionalities but to which plasma proteins adsorb efficiently. Plasma proteins thus play a dual role in moderating contact activation of the plasma coagulation cascade. The principal role is impeding FXII contact with activating surfaces but this same effect can displace FXIIa from an activating surface into solution where the protease can potentiate subsequent steps of the plasma coagulation cascade. PMID:21982294

Yeh, Chyi-Huey Josh; Dimachkie, Ziad O.; Golas, Avantika; Cheng, Alice; Parhi, Purnendu; Vogler, Erwin A.

2011-01-01

440

Contact activation of blood plasma and factor XII by ion-exchange resins.  

PubMed

Sepharose ion-exchange particles bearing strong Lewis acid/base functional groups (sulfopropyl, carboxymethyl, quaternary ammonium, dimethyl aminoethyl, and iminodiacetic acid) exhibiting high plasma protein adsorbent capacities are shown to be more efficient activators of blood factor XII in neat-buffer solution than either hydrophilic clean-glass particles or hydrophobic octyl sepharose particles (FXII (activator)?(surface) FXIIa; a.k.a autoactivation, where FXII is the zymogen and FXIIa is a procoagulant protease). In sharp contrast to the clean-glass standard of comparison, ion-exchange activators are shown to be inefficient activators of blood plasma coagulation. These contrasting activation properties are proposed to be due to the moderating effect of plasma-protein adsorption on plasma coagulation. Efficient adsorption of blood-plasma proteins unrelated to the coagulation cascade impedes FXII contacts with ion-exchange particles immersed in plasma, reducing autoactivation, and causing sluggish plasma coagulation. By contrast, plasma proteins do not adsorb to hydrophilic clean glass and efficient autoactivation leads directly to efficient activation of plasma coagulation. It is also shown that competitive-protein adsorption can displace FXIIa adsorbed to the surface of ion-exchange resins. As a consequence of highly-efficient autoactivation and FXIIa displacement by plasma proteins, ion-exchange particles are slightly more efficient activators of plasma coagulation than hydrophobic octyl sepharose particles that do not bear strong Lewis acid/base surface functionalities but to which plasma proteins adsorb efficiently. Plasma proteins thus play a dual role in moderating contact activation of the plasma coagulation cascade. The principal role is impeding FXII contact with activating surfaces, but this same effect can displace FXIIa from an activating surface into solution where the protease can potentiate subsequent steps of the plasma coagulation cascade. PMID:21982294

Josh Yeh, Chyi-Huey; Dimachkie, Ziad O; Golas, Avantika; Cheng, Alice; Parhi, Purnendu; Vogler, Erwin A

2012-01-01

441

Chaotic behavior of ion exchange phenomena in polymer gel electrolytes through irradiated polymeric membrane  

E-print Network

A desktop experiment has been done to show the nonlinearity in the I-V characteristics of an ion conducting electrochemical micro-system. Its chaotic dynamics is being reported for the first time which has been captured by an electronic circuit. Polyvinylidene fluoride-co-hexafluoropropene (PVdF-HFP) gel electrolyte comprising of a combination of plasticizers (ethylene carbonate and propylene carbonate) and salts have been prepared to study the exchange of ions through porous poly ethylene terephthalate (PET) membranes. The nonlinearity of this system is due to the ion exchange of the polymer gel electrolytes (PGEs) through a porous membrane. The different regimes of spiking and non-spiking chaotic motions are being presented. The possible applications are highlighted.

Sangeeta Rawat; Barnamala Saha; Awadhesh Prasad; Amita Chandra

2012-04-18

442

Binary--single-star scattering VII. Hard Binary Exchange Cross Sections for Arbitrary Mass Ratios: Numerical Results and Semi-Analytic Fits  

E-print Network

We present the first comprehensive fitting formula for exchange reactions of arbitrary mass ratios. In a comparison with numerical results, this expression is shown to be accurate in the hard binary limit to within 25\\% for most mass ratios. The result will be useful in forming quantitative estimates for the branching ratios of various exchange reactions in astrophysical applications. For example, it can be used to construct quantitative formation scenarios for unusual objects in globular clusters, such as binaries containing a pulsar.

D. C. Heggie; P. Hut; S. L. W. McMillan

1996-04-02

443

Propagation of charge-exchange plasma produced by an ion thruster  

NASA Technical Reports Server (NTRS)

Under the proper conditions there is an end-effect of a long, cylindrical Langmuir probe which allows a significant increase in collected ion current when the probe is aligned with a flowing plasma. This effect was used to determine the charge-exchange plasma flow direction at various locations relative to the ion thruster. The ion current collected by the probe as a function of its angle with respect to the plasma flow allows determination of the plasma density and plasma flow velocity at the probe's location upstream of the ion thruster optics. The density values obtained from the ion current agreed to within a factor of two of density values obtained by typical voltage-current Langmuir probe characteristics.

Carruth, M. R., Jr.; Brady, M. E.

1981-01-01

444

Competitive migration behaviors of multiple ions and their impacts on ion-exchange resin packed microbial desalination cell.  

PubMed

Mixed ion-exchange resins packed microbial desalination cell (R-MDC) could stabilize the internal resistance, however, the impacts of multiple ions on R-MDC performance was unclear. This study investigated the desalination performance, multiple ions migration behaviors and their impacts on R-MDCs fed with salt solution containing multiple anions and cations. Results showed that R-MDC removed multiple anions better than multiple cations with desalination efficiency of 99% (effluent conductivity <0.05 ms/cm) at hydraulic retention time of 50 h. Competitive migration order was SO4(2-)>NO3(-)>Cl(-) for anions and Ca(2+)?Mg(2+)>NH4(+)>Na(+) for cations, jointly affected by both their molar conductivity and exchange selectivity on resins. After long-term operation, the existence of higher concentration Ca(2+) and Mg(2+) caused the electric conductivity of mixed resins decrease and scaling on the surface of cation-exchange membrane adjoined with cathode chamber, suggesting that R-MDC would be more suitable for desalination of water with lower hardness. PMID:23982060

Zuo, Kuichang; Yuan, Lulu; Wei, Jincheng; Liang, Peng; Huang, Xia

2013-10-01

445

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

PubMed

Many studies in pharmacology, toxicology and environmental science require a method for determining the freely dissolved concentration of a target substance. A recently developed tool for this purpose is equilibrium passive sampling with polymeric materials. However, this method has rarely been applied to ionic organic substances, primarily due to limited availability of convenient sorption materials. This study introduces ion exchange membranes (IEMs) as a novel passive sampling material for organic ions. The partitioning of 4-ethylbenzene-1-sulfonate, 2,4-dichlorophenoxyacetic acid and pentachlorophenol to one anion exchange membrane (FAS) and of difenzoquat, nicotine and verapamil to one cation exchange membrane (FKS) was investigated. All test substances exhibited a sufficiently high affinity for the respective IEM with logarithmic IEM-water partition coefficients >2.3. Sorption equilibrium was established quickly, within several hours for the FAS membrane and within 1-3 days for the FKS membrane. For permanently charged substances the partitioning to the IEMs was independent of pH, but was influenced by the salt composition of the test solution. For all test substances sorption to IEM was dependent on the substance concentration. Bovine serum albumin-water partition coefficients determined by passive sampling with IEMs agree well with those determined by the conventional dialysis method. The results of this study indicate that IEMs exhibit the potential to measure freely dissolved concentrations of organic ions in a simple and time-saving manner. PMID:25454126

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

2014-11-28

446

Forward and reverse ion-exchange kinetics for some alkali and alkaline earth metal ions on amorphous zirconium(IV) aluminophosphate  

SciTech Connect

The Nernst-Planck equations are applied to study the ion-exchange kinetics on the surface of zirconium(IV) aluminophosphate for Li{sup +}/H{sup +}, Na{sup +}/H{sup +}, K{sup +}/H{sup +}, Mg{sup 2+}/H{sup +}, Ca{sup 2+}/H{sup +}, and Sr{sup 2+}/H{sup +} exchanges in the forward and reverse directions under the conditions favoring particle diffusion. On the basis of these studies, various physical parameters such as the self-diffusion coefficient (D{sub 0}), the energy of activation (E{sub a}), and the entropy of activation ({Delta}S*) have been determined and a correlation has been made of these parameters with the ion-exchange characteristics of the material. The study gives an insight into the ion-exchange processes going on in the exchanger phase and its potential use in metal ion separations.

Varshney, K.G.; Pandith, A.H.

1999-10-26

447

Planar, buried, ion-exchanged glass waveguides - Diffusion characteristics  

NASA Astrophysics Data System (ADS)

A study of Ag(+)-Na(+) exchange in soda-lime silicate glasses in a molten bath containing a mixture of NaNO3 and Ag(+) is performed. Concentration profiles obtained using backscattered electrons in an SEM indicate that with no applied field the profile is given by the complementary error function. The estimated 0.133 sq micron/min self-diffusion coefficient value for low concentrations monotonically increases with surface concentration, C(0), until it saturates at about 0.3 sq microns/min for C(0) greater than 0.001 MF, though square root dependence of diffusion depth with time is independent of C(0). The effective depth of diffusion increases with an external field. Experimental results confirmed theoretical predictions, and a 15.55 sq micron/V mobility-of-Ag(+)-in-glass value was obtained. Finally, a two-step process is modified by performing a second diffusion in pure sodium nitrate to produce a buried symmetrical fiber-like profile.

Ramaswamy, R. V.; Najafi, S. I.

1986-06-01

448

Two-column ion-exchange method for the determination of copper-complexing capacity and conditional stability constants of copper complexes for ligands in natural waters.  

PubMed

Sample solutions titrated with Cu(2+) ions are passed sequentially through two ion-exchange columns in an automated flow system. The first column is packed with Chelex-100 resin and retains Cu(2+) ions that are free or derived from copper complexes that dissociate in the column. The second column is packed with AG MP-1 anion-exchange resin and retains negatively charged Cu(II) complexes. The retained copper species are then eluted from the columns and determined on-line with a flame atomic-absorption spectrophotometer. It is necessary to correct for a small fraction of free Cu(2+) ions that pass through the first column and are retained by the second column. The Cu(II)-complexing capacity of sample solutions is determined from plots of the concentration ratio of free Cu(2+) ions to Cu(II) complexes vs. the concentration of free Cu(2+) ions. Conditional stability constants of the copper complexes are also estimated from these plots. The complexing capacity of sample solutions is also determined rapidly by measuring the concentration of complexed Cu(II) after spiking the sample with an excess of Cu(2+) ions. The sample solutions tested were 4.0muM NTA, 4.0-mg/l. humic acid, and a river water. PMID:18964688

Liu, Y; Ingle, J D

1989-01-01

449

Synthesis and Characterization of Templated Ion Exchange Resins for the Selective Complexation of Actinide Ions  

SciTech Connect

The purpose of this research is to develop a polymeric extractant for the selective complexation of uranyl ions (and subsequently other actinyl and actinide ions) from aqueous solutions (lakes, streams, waste tanks and even body fluids). Chemical insights into what makes a good complexation site will be used to synthesize reagents tailor-made for the complexation of uranyl and other actinide ions. These insights, derived from studies of molecular recognition include ion coordination number and geometry, ionic size and ionic shape, as well as ion to ligand thermodynamic affinity. Selectivity for a specific actinide ion will be obtained by providing the polymers with cavities lined with complexing ligands so arranged as to match the charge, coordination number, coordination geometry, and size of the actinide metal ion. These cavity-containing polymers will be produced by using a specific ion (or surrogate) as a template around which monomeric complexing ligands will be polymerized. The complexing ligands will be ones containing functional groups known to form stable complexes with a specific ion and less stable complexes with other cations. Prior investigator's approaches for making templated resins for metal ions have had marginal success. We have extended and amended these methodologies in our work with Pb(II) and uranyl ion, by changing the order of the steps, by the inclusion of sonication, by using higher complex loading, and the selection of functional groups with better complexation constants. This has resulted in significant improvements to selectivity. The unusual shape of the uranyl ion suggests that this approach will result in even greater selectivities than already observed for Pb(II). Preliminary data obtained for uranyl templated polymers shows unprecedented selectivity and has resulted in the first ion selective electrode for uranyl ion.

Murray, George M.; Uy, O. Manual murragm1@aplcomm.jhuapl.edu; uyom1@aplmsg.jhuapl.edu

2001-03-01

450

Kinetic electron and ion instability of the lunar wake simulated at physical mass ratio  

NASA Astrophysics Data System (ADS)

The solar wind wake behind the moon is studied with 1D electrostatic particle-in-cell (PIC) simulations using a physical ion to electron mass ratio (unlike prior investigations); the simulations also apply more generally to supersonic flow of dense magnetized plasma past non-magnetic objects. A hybrid electrostatic Boltzmann electron treatment is first used to investigate the ion stability in the absence of kinetic electron effects, showing that the ions are two-stream unstable for downstream wake distances (in lunar radii) greater than about three times the solar wind Mach number. Simulations with PIC electrons are then used to show that kinetic electron effects can lead to disruption of the ion beams at least three times closer to the moon than in the hybrid simulations. This disruption occurs as the result of a novel wake phenomenon: the non-linear growth of electron holes spawned from a narrow dimple in the electron velocity distribution. Most of the holes arising from the dimple are small and quickly leave the wake, approximately following the unperturbed electron phase-space trajectories, but some holes originating near the center of the wake remain and grow large enough to trigger disruption of the ion beams. Non-linear kinetic-electron effects are therefore essential to a comprehensive understanding of the 1D electrostatic stability of such wakes, and possible observational signatures in ARTEMIS data from the lunar wake are discussed.

Haakonsen, Christian Bernt; Hutchinson, Ian H.; Zhou, Chuteng

2015-03-01

451

Preparation of Ion Exchange Films for Solid-Phase Spectrophotometry and Solid-Phase Fluorometry  

NASA Technical Reports Server (NTRS)

Atomic spectroscopy has dominated the field of trace inorganic analysis because of its high sensitivity and selectivity. The advantages gained by the atomic spectroscopies come with the disadvantage of expensive and often complicated instrumentation. Solid-phase spectroscopy, in which the analyte is preconcentrated on a solid medium followed by conventional spectrophotometry or fluorometry, requires less expensive instrumentation and has considerable sensitivity and selectivity. The sensitivity gains come from preconcentration and the use of chromophore (or fluorophore) developers and the selectivity is achieved by use of ion exchange conditions that favor the analyte in combination with speciative chromophores. Little work has been done to optimize the ion exchange medium (IEM) associated with these techniques. In this report we present a method for making ion exchange polymer films, which considerably simplify the solid-phase spectroscopic techniques. The polymer consists of formaldehyde-crosslinked polyvinyl alcohol with polyacrylic acid entrapped therein. The films are a carboxylate weak cation exchanger in the calcium form. They are mechanically sturdy and optically transparent in the ultraviolet and visible portion of the spectrum, which makes them suitable for spectrophotometry and fluorometry.

Hill, Carol M.; Street, Kenneth W.; Tanner, Stephen P.; Philipp, Warren H.

2000-01-01

452

Ion exchange membrane cathodes for scalable microbial fuel cells.  

PubMed

One of the main challenges for using microbial fuel cells (MFCs) is developing materials and architectures that are economical and generate high power densities. The performance of two cathodes constructed from two low-cost anion (AEM) and cation (CEM) exchange membranes was compared to that achieved using an ultrafiltration (UF) cathode, when the membranes were made electrically conductive using graphite paint and a nonprecious metal catalyst (CoTMPP). The best performance in single-chamber MFCs using graphite fiber brush anodes was achieved using an AEM cathode with the conductive coating facing the solution, at a catalyst loading of 0.5 mg/cm2 CoTMPP. The maximum power densitywas 449 mW/ m2 (normalized to the projected cathode surface area) or 13.1 W/m3 (total reactor volume), with a Coulombic efficiency up to 70% in a 50 mM phosphate buffer solution (PBS) using acetate. Decreasing the CoTMPP loading by 40-80% reduced power by 28-56%, with only 16% of the power (72 mW/m2) generated using an AEM cathode lacking a catalyst. Using a current collector (a stainless steel mesh) pressed against the inside surface of the AEM cathode and 200 mM PBS, the maximum power produced was further increased to 728 mW/m2 (21.2 W/m3). The use of AEM cathodes and brush anodes provides comparable performance to similar systems that use materials costing nearly an order of magnitude more (carbon paper electrodes) and thus represent more useful materials for reducing the costs of MFCs for wastewater treatment applications. PMID:18853817

Zuo, Yi; Cheng, Shaoan; Logan, Bruce E

2008-09-15

453

Ion-exchange fractionation of copper and zinc isotopes  

NASA Astrophysics Data System (ADS)

Whether transition element isotopes can be fractionated at equilibrium in nature is still uncertain. Standard solutions of Cu and Zn were eluted on an anion-exchange resin, and the isotopic compositions of Cu (with respect to Zn) of the eluted fractions were measured by multiple-collector inductively coupled plasma mass spectrometry. It was found that for pure Cu solutions, the elution curves are consistent with a 63Cu/ 65Cu mass fractionation coefficient of 0.46‰ in 7 mol/L HCl and 0.67‰ in 3 mol/L HCl between the resin and the solution. Batch fractionation experiments confirm that equilibrium fractionation of Cu between resin and 7 mol/L HCl is ˜0.4‰ and therefore indicates that there is no need to invoke kinetic fractionation during the elution. Zn isotope fractionation is an order of magnitude smaller, with a 66Zn/ 68Zn fractionation factor of 0.02‰ in 12 mol/L HCl. Cu isotope fractionation results determined from a chalcopyrite solution in 7 mol/L HCl give a fractionation factor of 0.58‰, which indicates that Fe may interfere with Cu fractionation. Comparison of Cu and Zn results suggests that the extent of Cu isotopic fractionation may signal the presence of so far unidentified polynuclear complexes in solution. In contrast, we see no compelling reason to ascribe isotope fractionation to the coexistence of different oxidation states. We further suggest that published evidence for iron isotopic fractionation in nature and in laboratory experiments may indicate the distortion of low-spin Fe tetrahedral complexes. The isotope geochemistry of transition elements may shed new light on their coordination chemistry. Their isotopic fractionation in the natural environment may be interpreted using models of thermodynamic fractionation.

Maréchal, Chloé; Albarède, Francis

2002-05-01

454

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

PubMed

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 dioxi