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

Science.gov (United States)

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

2014-01-01

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

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

Science.gov (United States)

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

2015-07-01

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

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

Science.gov (United States)

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

2017-09-13

Ion exchange is a ubiquitous phenomenon central to wide industrial applications, ranging from traditional (bio)chemical separation to the emerging chimie douce synthesis of materials with metastable structure for batteries and other energy applications. The exchange process is complex, involving substitution and transport of different ions under non-equilibrium conditions, and thus difficult to probe, leaving a gap in mechanistic understanding of kinetic exchange pathways toward final products. Herein, we report in situ tracking kinetic pathways of Li + /Na + substitution during solvothermal ion-exchange synthesis of Li x Na 1.5-x VOPO 4 F 0.5 (0 ≤ x ≤ 1.5), a promising multi-Li polyanionic cathode for batteries. The real-time observation, corroborated by first-principles calculations, reveals a selective replacement of Na + by Li + , leading to peculiar Na + /Li + /vacancy orderings in the intermediates. Contradicting the traditional belief of facile topotactic substitution via solid solution reaction, an abrupt two-phase transformation occurs and predominantly governs the kinetics of ion exchange and transport in the 1D polyanionic framework, consequently leading to significant difference of Li stoichiometry and electrochemical properties in the exchanged products. The findings may help to pave the way for rational design of ion exchange synthesis for making new materials.

Silver-Ion-Exchanged Nanostructured Zeolite X as Antibacterial Agent with Superior Ion Release Kinetics and Efficacy against Methicillin-Resistant Staphylococcus aureus.

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Chen, Shaojiang; Popovich, John; Iannuzo, Natalie; Haydel, Shelley E; Seo, Dong-Kyun

2017-11-15

As antibiotic resistance continues to be a major public health problem, antimicrobial alternatives have become critically important. Nanostructured zeolites have been considered as an ideal host for improving popular antimicrobial silver-ion-exchanged zeolites, because with very short diffusion path lengths they offer advantages in ion diffusion and release over their conventional microsized zeolite counterparts. Herein, comprehensive studies are reported on materials characteristics, silver-ion release kinetics, and antibacterial properties of silver-ion-exchanged nanostructured zeolite X with comparisons to conventional microsized silver-ion-exchanged zeolite (∼2 μm) as a reference. The nanostructured zeolites are submicrometer-sized aggregates (100-700 nm) made up of primary zeolite particles with an average primary particle size of 24 nm. The silver-ion-exchanged nanostructured zeolite released twice the concentration of silver ions at a rate approximately three times faster than the reference. The material exhibited rapid antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 4 to 16 μg/mL after 24 h exposure in various growth media and a minimum bactericidal concentration (MBC; >99.9% population reduction) of 1 μg/mL after 2 h in water. While high concentrations of silver-ion-exchanged nanostructured zeolite X were ineffective at reducing MRSA biofilm cell viability, efficacy increased at lower concentrations. In consideration of potential medical applications, cytotoxicity of the silver-ion-exchanged nanostructured zeolite X was also investigated. After 4 days of incubation, significant reduction in eukaryotic cell viability was observed only at concentrations 4-16-fold greater than the 24 h MIC, indicating low cytotoxicity of the material. Our results establish silver-ion-exchanged nanostructured zeolites as an effective antibacterial material against dangerous

Application to ion exchange study of an interferometry method

International Nuclear Information System (INIS)

Platzer, R.

1960-01-01

The numerous experiments carried out on ion exchange between clay suspensions and solutions have so far been done by studying the equilibrium between the two phases; by this method it is very difficult to obtain the kinetic properties of the exchange reactions. At method consisting of observation with an interferential microscope using polarised white light shows up the variations in concentration which take place during the ion exchange between an ionic solution and a montmorillonite slab as well as between an ionic solution and a grain of organic ion exchanger. By analysing the results it will be possible to compare the exchange constants of organic ion exchangers with those of mineral ion exchangers. (author) [fr

Murmanite and lomonosovite as Ag-selective ionites: kinetics and products of ion exchange in aqueous AgNO3 solutions

Science.gov (United States)

Lykova, Inna S.; Chukanov, Nikita V.; Kazakov, Anatoliy I.; Tarasov, Viktor P.; Pekov, Igor V.; Yapaskurt, Vasiliy O.; Chervonnaya, Nadezhda A.

2013-09-01

Products and kinetics of ion exchange of heterophyllosilicate minerals lomonosovite and murmanite with aqueous AgNO3 solutions under low-temperature conditions have been studied using scanning electron microscopy, electron microprobe analysis, single-crystal X-ray diffraction, infrared spectroscopy, 23Na nuclear magnetic resonance spectroscopy and dynamic calorimetry. Both minerals show strong affinity for silver in cation exchange. Simplified formulae of Ag-exchanged forms of murmanite and lomonosovite are (Ag3.0Ca0.5Na0.5) (Ti,Nb,Mn,Fe)3.7-4 (Si2O7)2O4·4(H2O,OH) and (Ag8.2Na1.2Ca0.3) (Ti,Nb,Mn,Fe)3.9-4 (Si2O7)2 (PO4)1.9O4· xH2O, respectively. The reaction of ion exchange for murmanite follows the first-order kinetic model up to ca. 70-80 % conversion. The rate of the process is described by the equation k(h-1) = 107.64±0.60 exp[-(12.2 ± 0.9)·103/RT]. The average heat release value in the temperature range 39.4-72 °C is 230 J g-1. The cation exchange is limited by processes in solid state, most probably binding of silver.

Comparative study on bromide and iodide ion-isotopic exchange reactions using strongly basic anion exchange resin Duolite A-113

International Nuclear Information System (INIS)

Lokhande, R.S.; Dole, M.H.; Singare, P.U.

2006-01-01

Kinetics of ion-isotopic exchange reaction was studied using industrial grade ion exchange resin Duolite A-113. The radioactive isotopes 131 I and 82 Br were used to trace the ion-isotopic exchange reaction. The experiments were performed in the temperature range of 26.0degC to 43.0degC and the concentration of external ionic solution varying from 0.005 M to 0.100 M. For bromide ion-isotopic exchange reaction, the calculated values of specific reaction rate, initial rate of bromide ion exchange, and amount of bromide ions exchanged were obtained higher than that for iodide ion-isotopic exchange reaction under identical experimental conditions. The observed variation in the results for two ion-isotopic exchange reactions was due to the difference in the ionic size of bromide and iodide ions. (author)

Experimental Characterization and Modelization of Ion Exchange Kinetics for a Carboxylic Resin in Infinite Solution Volume Conditions. Application to Monovalent-Trivalent Cations Exchange

Energy Technology Data Exchange (ETDEWEB)

Picart, S.; Mokhtari, H.; Jobelin, I. [CEA Marcoule, Nucl Energy Div, RadioChem and Proc Dept, Actinides Chem and Convers Lab, F-30207 Bagnols Sur Ceze (France); Ramiere, I. [Fuel Simulat Lab, Fuel Study Dept, F-13108 St Paul Les Durance (France)

2010-07-01

This study is devoted to the characterization of ion exchange inside a microsphere of carboxylic resin. It aims at describing the kinetics of this exchange reaction which is known to be controlled by interdiffusion in the particle. The fractional attainment of equilibrium function of time depends on the concentration of the cations in the resin which can be modelled by the Nernst-Planck equation. A powerful approach for the numerical resolution of this equation is introduced in this paper. This modeling is based on the work of Helfferich but involves an implicit numerical scheme which reduces the computational cost. Knowing the diffusion coefficients of the cations in the resin and the radius of the spherical exchanger, the kinetics can be hence completely determined. When those diffusion parameters are missing, they can be deduced by fitting experimental data of fractional attainment of equilibrium. An efficient optimization tool coupled with the implicit resolution has been developed for this purpose. A monovalent/trivalent cation exchange had been experimentally characterized for a carboxylic resin. Diffusion coefficients and concentration profiles in the resin were then deduced through this new model. (authors)

Experimental Characterization and Modelization of Ion Exchange Kinetics for a Carboxylic Resin in Infinite Solution Volume Conditions. Application to Monovalent-Trivalent Cations Exchange

International Nuclear Information System (INIS)

Picart, S.; Mokhtari, H.; Jobelin, I.; Ramiere, I.

2010-01-01

This study is devoted to the characterization of ion exchange inside a microsphere of carboxylic resin. It aims at describing the kinetics of this exchange reaction which is known to be controlled by interdiffusion in the particle. The fractional attainment of equilibrium function of time depends on the concentration of the cations in the resin which can be modelled by the Nernst-Planck equation. A powerful approach for the numerical resolution of this equation is introduced in this paper. This modeling is based on the work of Helfferich but involves an implicit numerical scheme which reduces the computational cost. Knowing the diffusion coefficients of the cations in the resin and the radius of the spherical exchanger, the kinetics can be hence completely determined. When those diffusion parameters are missing, they can be deduced by fitting experimental data of fractional attainment of equilibrium. An efficient optimization tool coupled with the implicit resolution has been developed for this purpose. A monovalent/trivalent cation exchange had been experimentally characterized for a carboxylic resin. Diffusion coefficients and concentration profiles in the resin were then deduced through this new model. (authors)

Ion-exchange Resin Catalyzed Esterification of Lactic Acid with Isopropanol: a Kinetic Study

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Amrit P. Toor

2011-05-01

Full Text Available The kinetic behavior of esterification of lactic acid with isopropanol over an acidic cation exchange resin, Amberlyst 15, was studied under isothermal condition. Isopropyl lactate synthesized in this reaction is an important pharmaceutical intermediate. The experiments were carried out in a stirred batch reactor in the temperature range of 323.15 to 353.15 K. The effect of various parameters such as temperature, molar ratio and catalyst loading was studied. Variation in parameters on rate of reaction demonstrated that the reaction was intrinsically controlled. Kinetic modeling was performed using Eley-Rideal model which acceptably fits the experimental data. The activation energy was found to be 22.007 kJ/mol and frequency factor was 0.036809 l2 g-1 mol-1 min-1 for forward reaction. The value of entropy for the forward reaction was found to be 182.317 J K-1 mol-1 . © 2011 BCREC UNDIP. All rights reserved(Received: 19th January 2011, Revised: 16th March 2011; Accepted: 16th March 2011[How to Cite: A.P. Toor, M. Sharma, S. Thakur, and R. K. Wanchoo. (2011. Ion-exchange Resin Catalyzed Esterification of Lactic Acid with Isopropanol: a Kinetic Study. Bulletin of Chemical Reaction Engineering and Catalysis, 6(1: 39-45. doi:10.9767/bcrec.6.1.791.39-45][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.791.39-45 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/791 ] | View in  

SOLVENT EFFECTS ON THE HYDRATION OF CYCLOHEXENE CATALYZED BY A STRONG ACID ION-EXCHANGE RESIN .2. EFFECT OF SULFOLANE ON THE REACTION-KINETICS

NARCIS (Netherlands)

PANNEMAN, HJ; BEENACKERS, AACM

The kinetics of the' hydration of cyclohexene, catalyzed by a strong acid ion-exchange resin, have been studied in a packed bed reactor at temperatures between 353 and 413 K and a pressure of 20 bar. The kinetic rate constants were measured as a function of temperature and solvent composition (0-90

Kinetics and thermodynamic for sorption of arsenate by Lanthanum-exchanged zeolite

International Nuclear Information System (INIS)

Mohd Jelas Haron; Saiful Adli Masdan; Mohd Zobir Hussein; Zulkarnain Zainal; Anuar Kassim

2007-01-01

negative values of ΔG degree meant that the sorption of As (V) ions on La-exchanged zeolite was spontaneous, perhaps because the La (III) had high affinity towards the arsenic ion as indicated by a low K sp value of of lanthanum arsenate. A slightly positive entropy change for sorption of As (V) ion on La-exchanged zeolite could be due to fixation of the ions on the La (III) exchange sites that was randomly distributed on the sorbents. The kinetics study showed that the As (V) sorption followed first order kinetic model. The first-order kinetic constants for the sorption are 2.77x10 -3 , 2.25x10 -3 and 1.60x10 -3 min -1 for La-ZX, La-ZSM and La-ZA, respectively. (author)

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

Science.gov (United States)

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

2010-06-01

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

Kinetic study of the isotopic exchange of Na+ and Zn2+ ions on iron and chromium titanates

International Nuclear Information System (INIS)

Zakaria, E.S.; Ali, I.M.; Aly, H.F.

2004-01-01

Iron(III) (FeTi) and chromium (III) titanates (CrTi) were prepared as cation exchange materials in a granular form. The rate of the isotopic exchange of Na + /*Na + and Zn 2+ /*Zn 2+ between aqueous solution and iron(III) and chromium(III) titanates in Na + or Zn 2+ form has been carried out radiometrically in the 25-60 deg C temperature range. The exchange rate is controlled by a particle diffusion mechanism and experimental and theoretical approaches have been used to obtain the rate of diffusion through the spherical particles of the exchangers. The values of self diffusion (D-bar) of Na + and Zn 2+ ions were measured at different operation conditions, particle size, reaction temperatures and drying temperatures of the matrix. The values of kinetic and thermodynamic parameters were calculated and their significance discussed. (author)

Chromate ion-exchange study for cooling water

International Nuclear Information System (INIS)

Sengupta, A.K.

1985-01-01

In spite of high chromate selectivity, the ion-exchange process for Cr(IV) recovery from cooling tower blowdown is yet to be commercially popular. Possible degradation of the ion-exchange resin by the oxidative action of Cr(IV) during ion exchange has been considered as the prime obstacle. Resins have been manufactured with fairly acceptable properties to withstand both physical attrition and chemical oxidation. Demonstrated during the course of this research is early, gradual Cr(VI) breakthrough during fixed-bed column runs at acidic pH in the presence of competing sulfate and chloride anions. The advantage of high chromate selectivity is essentially lost due to the early Cr(VI) breakthrough because the column runs are always terminated after a pre-determined level of Cr(VI) has appeared in the treated water. Experimental results provide sufficient evidence that this is not due to poor column kinetics or electrolyte penetration. The chromate ion-exchange mechanism has been investigated in order to explain the foregoing anomalies for the chromate-exchange process. The knowledge of chromate ion-exchange mechanism has been used to overcome the shortcoming of gradual Cr(VI) breakthrough. This study shows that: (a) a continuous counter-current ion-exchange system theoretically offers much higher Cr(VI) removal capacity compared to conventional single-unit fixed-bed system for any pre-determined level of Cr(VI) breakthrough; (b) by modifying the resin composition, the gradual Cr(VI) breakthrough can be greatly eliminated

Time-resolved pulsed hydrogen/deuterium exchange mass spectrometry probes gaseous proteins structural kinetics.

Science.gov (United States)

Rajabi, Khadijeh

2015-01-01

A pulsed hydrogen/deuterium exchange (HDX) method has been developed for rapid monitoring of the exchange kinetics of protein ions with D2O a few milliseconds after electrospray ionization (ESI). The stepwise gradual evolution of HDX of multiply charged protein ions was monitored using the pulsed HDX mass spectrometry technique. Upon introducing a very short pulse of D2O (in the μs to ms time scale) into the linear ion trap (LIT) of a time-of-flight (TOF) mass spectrometer, bimodal distributions were detected for the ions of cytochrome c and ubiquitin. Mechanistic details of HDX reactions for ubiquitin and cytochrome c in the gas phase were uncovered and the structural transitions were followed by analyzing the kinetics of HDX.

The use of fibrous ion exchangers in gold hydrometallurgy

Science.gov (United States)

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

2002-10-01

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

Scandium sorption by immobilized microdispersed forms of phosporus-containing ion exchangers

International Nuclear Information System (INIS)

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

1991-01-01

The possibility to improve considerably kinetics of scandium sorption by phosphate ion exchangers, immobilized into polyacrylonitrile (PAN) fibers, as compared with granular samples of ion exchangers, was shown. The influence of dispersion degree of immobilized ionite particles on sorption rate was studied. It is ascertained that the ionite grinding to the particle size ≤ 52 μm is sufficient for the rate increase by 1-1.5 orders. A lower swelling of the immobilized ion exchanger is its additional advantage as compared with granular form

Solvent effects on the kinetics of the chlorine isotopic exchange reaction between chloride ion and O,O-diphenyl phosphorochloridate or O,O-diphenyl phosphorchloridothioate

International Nuclear Information System (INIS)

Mikolajczyk, M.; Slebocka-Tilk, H.; Reimschussel, W.

1982-01-01

The effect of solvent on the kinetics of the chlorine isotopic exchange reaction between 36 Cl- ions and O,O-diphenyl phosphorochloridate or O,O-diphenyl phosphorochloridothioate has been investigated in nitromethane, acetonitrile, propylene carbonate, benzonitrile, nitrobenzene, and hexamethyl-phosphoric triamide. The rate constants decrease with increasing electrophilicity of the solvent. A good correlation between the logarithm of the rate constants and acceptor number (AN) of the solvent was obtained with identical slopes for reactions with phosphoryl and thiophosporyl compounds. The slopes for the dependence of ΔH or TΔS vs. AN for chlorine isotopic exchange in (PHO) 2 pace are opposite those for the exchange reaction in (PHO) 2 PSCl, so a constant ratio of k/sub p=O//k/sub p=s/ is observed, resulting from compensation of ΔH by ΔS. The effect of solvent on the initial state (from solubility measurements) and the transition state of the reaction between (PhO) 2 PSCl and the Cl- ion was evaluated. Changes of solvation of (PHO) 2 PSCE have practically no effect on the kinetics of the reactions. Changes of solvation of the chloride ion and of the transition state primarily influence the rate constants and activation parameters of the investigated isotopic-exchange reaction

Application of personal computers to study the kinetics of heterogeneous isotopic exchange

International Nuclear Information System (INIS)

Koernyei, Jozsef; Lakatos, Mihaly

1985-01-01

The kinetics of some heterogeneous isotopic exchange reactions of alkaline metal ions between solid (crystalline zirconium phosphate) and liquid phases were investigated. Ion diffusion in solid phase was considered as rate controlling step. The Laplace transformation solution of Fick's II law was used with a Sinclair ZX Spectrum personal computer. In some cases the exchange reaction should be regarded as a superposition of diffusion and a first order process. (author)

Kinetics of the exchange between fibrous manganese dioxide and Mn2+ ions in solution

International Nuclear Information System (INIS)

Rophael, M.W.

1983-01-01

The rate of exchange between fibrous manganese dioxide epsilon-MnO 2 and a 0.1 M MnSO 4 solution at 25 0 C and pH 2.0 was higher than the corresponding rate at pH 5.4. When the solid was washed with dilute acid (pH 2.0) before the exchange at pH 2.0, the results of the exchange at the two pH values were similar. When epsilon-MnO 2 was partially reduced with N 2 H 4 .H 2 O solution before the exchange, the rate of exchange was appreciably higher than that obtained for the unreduced solid. The exchange, at nearly pH 2.0, between epsilon-MnO 2 and various concentrations of Mn(NO 3 ) 2 solutions was increased to a small extent as the concentration increased tenfold. The exchange was followed by using 56 Mn-labelled MnO 2 and by measuring the β activity acquired by the Mn 2+ ion solution. The activity induced in the solid MnO 2 was produced by irradiation with thermal neutrons from a 241 Am- 9 Be laboratory neutron source. The neutron activation of manganese oxides has the following advantages: (i) a relatively high level of activity can be induced in the 55 Mn of the irradiated oxide because of its 100% abundance and its high neutron activation cross section, whereas the oxygen is unaffected; (ii) the half-life of the product 56 Mn is 9274 s which is convenient for kinetic studies; (iii) the activity produced almost decays in 24 h. (Auth.)

Ion-Exchange Processes and Mechanisms in Glasses

International Nuclear Information System (INIS)

McGrail, B.P.; Icenhower, J.P.; Darab, J.G.; Shuh, D.K.; Baer, D.R.; Shutthanandan, V.; Thevuthasan, S.; Engelhard, M.H.; Steele, J.L.; Rodriguez, E.A.; Liu, P.; Ivanov, K.E.; Booth, C.H.; Nachimuthu, P.

2001-01-01

[14,15]. Renewed interest in alkali ion exchange reactions has come about because of interest in development of durable Na-rich silicate glasses for immobilization of low-activity waste (LAW) at Hanford, Washington [16] and high-level wastes in China [17]. In reactive transport simulations of a LAW glass disposed in a shallow subsurface facility, Chen, McGrail, and Engel [18] showed that ion-exchange reactions increased the radionuclide release rate by over two orders of magnitude when compared with simulations where ion exchange was excluded. Sheng, Luo, and Tang [17] conducted static tests in a simulated groundwater and showed that alkali ion exchange was the dominant release mechanism over a large temperature range. Although the significance of alkali ion exchange reactions in long-term disposal system performance has now been recognized, the fundamental processes and mechanisms controlling the exchange reactions are still remarkably poorly understood, especially with regard to how glass structure affects alkali ion exchange kinetics. Experimental studies of Na release from various simple silicate glasses are numerous [19-23]. However, in all previous studies of which we are aware, no attempt was made to distinguish between M + release through alkali exchange versus matrix dissolution. The release rate of alkali in all of the early work was convoluted by contributions from matrix dissolution, which dominates in dilute solutions. Also, none of the previous studies attempted to define the relationship, if any, between glass structure (composition) and the kinetics of the ion exchange reaction. The motivation behind this Environmental Management Science Project (EMSP) is to develop a better understanding of how glass structure impacts sodium ion exchange so that improved glasses can be developed. Development of low ion-exchange rate glasses may also permit engineers to use higher loadings in nuclear waste glasses, which would result in substantial savings in

Application of tracer isotope in kinetic study of first order ion exchange reaction

International Nuclear Information System (INIS)

Lokhande, R.S.; Singare, P.U.

1998-01-01

Analysis of first order ion exchange reaction rates at different temperatures (27 deg- 48 degC) and particularly at low concentration of potassium iodide solution (electrolyte) ranging from 0.005 M to 0.040 M is carried out by application of radioactive tracer isotope 131 I. With increase in concentration of electrolyte, amount of iodide ion exchanged in millimoles increases. Specific reaction rates of ion exchange reaction are calculated for different temperatures and for different amount of ion exchange resins. It is observed that with increase in temperature, reaction rate increases but the increase is more pronounced for increase in amount of ion exchange resins. For 0.005 M solution of electrolyte, the reaction rate increases from 0.121 min -1 at 27 degC to 0.178 min -1 at 48 degC. For 0.005 M solution of electrolyte the reaction rate increases from 0.121 min -1 at 27 degC to 0.178 min 1 at 48 degC. For 0.005 M solution of electrolyte at 27 degC the reaction rate increases from 0.121 min -1 for 1.0 g of resin to 0.368 min -1 for 5.0 g of resin. From the reaction rates calculated at different temperatures, energy of activation in kJ/mole is calculated. It is observed that for 0.005 M solution of electrolyte, energy of activation is 4.62 kJ/mole which decreases to 2.87 kJ/mole for increase in concentration of electrolyte to 0.100 M. (author)

Isotopic exchange rate of cobalt ions between hydrous tin(IV) oxide and aqueous solutions

International Nuclear Information System (INIS)

Inoue, Yasushi; Yamazaki, Hiromichi; Itami, Akira

1989-01-01

The isotopic exchange rate of cobalt ions between hydrous tin(IV) oxide ion exchanger and aqueous solutions was radiochemically measured to obtain fundamental data which are useful for elucidating the ion-exchange kinetics of the material for the transition metal elements. The rate can be understood by considering that the cobalt ions were present in the exchanger as three kinds of species: (A 1 ) Free ions which can diffuse in the exchanger particles, (A 2 ) Weakly bound ions to the exchange sites which exchange rapidly with A 1 , and (B) Covalently fixed ions to the exchange sites which exchange very slowly with A 1 . At low fraction of B, the rate is controlled by the diffusion of A 1 with the effective diffusion coefficient, D eff , the values of which depend on the concentration ratios of A 2 to A 1 . When B predominates over the A species, the concentration ratios of B to A 1 affect greatly D eff . The values of D eff and their activation energy(20 kJ/mol) were also estimated

Removal of Ca(II) and Mg(II) from potassium chromate solution on Amberlite IRC 748 synthetic resin by ion exchange

International Nuclear Information System (INIS)

Yu Zhihui; Qi Tao; Qu Jingkui; Wang Lina; Chu Jinglong

2009-01-01

Experimental measurements have been made on the batch ion exchange of Ca(II) and Mg(II) from potassium chromate solution using cation exchanger of Amberlite IRC 748 as K + form. The ion exchange behavior of two alkaline-earth metals on the resin, depending on contact time, pH, temperature and resin dosage was studied. The adsorption isotherms were described by means of the Langmuir and Freundlich isotherms. For Ca(II) ion, the Langmuir model represented the adsorption process better than the Freundlich model. The maximum ion exchange capacity was found to be 47.21 mg g -1 for Ca(II) and 27.70 mg g -1 for Mg(II). The kinetic data were tested using Lagergren-first-order and pseudo-second-order kinetic models. Kinetic data correlated well with the pseudo-second-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Various thermodynamic parameters such as Gibbs free energy (ΔG o ), enthalpy (ΔH o ) and entropy (ΔS o ) were also calculated. These parameters showed that the ion exchange of Ca(II) and Mg(II) from potassium chromate solution was feasible, spontaneous and endothermic process in nature. The activation energy of ion-exchange (E a ) was determined as 12.34 kJ mol -1 for Ca(II) and 9.865 kJ mol -1 for Mg(II) according to the Arrhenius equation.

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

Science.gov (United States)

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

2015-09-25

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

Hydrogen/deuterium exchange of multiply-protonated cytochrome c ions

International Nuclear Information System (INIS)

Wood, T.D.; Guan, Ziqiang; O'Connor, P.B.

1995-01-01

Low resolution measurements show gaseous multiply-protonated cytochrome c ions undergo hydrogen/deuterium (H/D) exchange with pseudo first-order kinetics at three distinct exchange levels, suggesting the co-existence of gaseous protein conformations. Although exchange levels first increase with increasing charge values, they decrease at the highest charge values, consistent with solution-phase behavior of cytochrome c, where the native structure unfolds with decreasing pH until folding into a compact A-state at lowest pH. High resolution measurements indicate the presence of at least six H/D exchange levels. Infrared (IR) laser heating and fast collisions via quadrupolar excitation (QE) increase H/D exchange levels (unfolding) while charge-stripping ions to lower charge values can increase or decrease H/D exchange levels (unfolding or folding). Wolynes has suggested studying proteins in vacuo could play an important role in delineating the contributions various forces play in the protein folding process, provided appropriate comparisons can be made between gas-phase and solution-phase structures

Isotopic exchange rate of sodium ions between hydrous metal oxides and aqueous solutions

International Nuclear Information System (INIS)

Inoue, Yasushi; Yamazaki, Hiromichi

1991-01-01

To elucidate the kinetics of ion-exchange reaction on hydrous metal oxide, the isotopic exchange rates of sodium ions between hydrous metal oxides such as hydrous tin (IV), niobium (V), zirconium (IV) and titanium (IV) oxides, and aqueous solutions were measured radiochemically and compared with each other. The rate of reaction cannot be understood by an unified view since the rate controlling step differs with the kind of exchangers. The rate constants relevant to each exchanger such as diffusion constants and their activation energies were also determined. (author)

Ion-exchange behaviour of hydrous zirconia in mixed solvents: capacity and kinetics of exchange

International Nuclear Information System (INIS)

Misak, N.Z.; Ghoneimy, H.F.

1982-01-01

The capacity of the Li + form of hydrous zirconia for Na + and Cs + increases in the presence of methanol. This may be due to the greater stability of Li + in methanol/water than in pure water and to dehydration of Na + and Cs + and their stronger interaction with the exchange sites, which may facilitate their replacing Li + . The ion-exchange capacity of zirconia for NO 3 - , Cl - and Br - is almost the same in aqueous solution and is not affected by addition of up to 90% (v/v) methanol, which probably shows that these anions are electrostatically bound in zirconia without specific interactions. The internal diffusion coefficients of the Na + /H + and Cl - /OH - systems decrease in the presence of alcohol: the decrease is highest with methanol and similar for ethanol and propan-2-ol. This is discussed in the light of ion solvation and alcohol penetration inside zirconia. (author)

Chemical exchange between UF6 and UF6- ion in anhydrous hydrofluoric acid

International Nuclear Information System (INIS)

Chatelet, J.; Luce, M.; Plurien, P.; Rigny, P.

1975-01-01

The chemical exchange between UF 6 and the UF 6 - ion is of potential interest for the separation of U isotopes. In this paper, results concerning the value of the separation factor and the kinetics of the homogeneous exchange are given [fr

Outlook for ion exchange

International Nuclear Information System (INIS)

Kunin, R.

1977-01-01

This paper presents the history and theory of ion exchange technology and discusses the usefulness of ion exchange resins which found broad applications in chemical operations. It is demonstrated that the theory of ion exchange technology seems to be moving away from the physical chemist back to the polymer chemist where it started originally. This but confronted the polymer chemists with some knotty problems. It is pointed out that one has still to learn how to use ion exchange materials as efficiently as possible in terms of the waste load that is being pumped into the environment. It is interesting to note that, whereas ion exchange is used for abating pollution, it is also a polluter. One must learn how to use ion exchange as an antipollution device, and at the same time minimize its polluting properties

Analytical applications of ion exchangers

CERN Document Server

Inczédy, J

1966-01-01

Analytical Applications of Ion Exchangers presents the laboratory use of ion-exchange resins. This book discusses the development in the analytical application of ion exchangers. Organized into 10 chapters, this book begins with an overview of the history and significance of ion exchangers for technical purposes. This text then describes the properties of ion exchangers, which are large molecular water-insoluble polyelectrolytes having a cross-linked structure that contains ionic groups. Other chapters consider the theories concerning the operation of ion-exchange resins and investigate th

Determination of kinetic parameters of heterogeneous isotopic exchange reaction

International Nuclear Information System (INIS)

Huang, Ting-Chia; Tsai, Fuan-Nan

1977-01-01

A mathematical model has been proposed for a heterogeneous isotopic exchange reaction which involves film diffusion, surface chemical reaction and intraparticle diffusion. The exchange equation to predict the exchange fraction as a function of time for the spherical particles immersed in a solution of finite volume has been derived. The relations between the exchange fraction and dimensionless time are plotted with xi(=ak sub(f)/KD sub(e)), xi 1 (=K 1 a 2 /D sub(e)) and final fractional uptake as parameters. From the values of the kinetic parameters xi and xi 1 , the relative importance of each limiting step is discussed. Experimental results of the isotopic exchange reaction of calcium ion in both system CaCO 3 (s)/Ca 2+ (aq) and system calcium type resin Dowex 50W-X8/Ca 2+ (aq) are coincident with the theoretical equation proposed in this study. (auth.)

Kinetics of isotopic exchange between calcium molybdate and molybdate ions in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Atun, G.; Ayar, N.; Bilgin, B. [Istanbul Univ. (Turkey). Dept. of Chemistry, Fac. of Engineering; Bodur, N.; Ayyildiz, H. [Cekmece Nuclear Research and Training Center, Istanbul (Turkey)

2007-07-01

The heterogeneous isotopic anion exchange kinetics and equilibria between calcium molybdate and sodium molybdate solutions have been studied by using {sup 99}Mo as tracer in batch experiments. The values of exchange ratio lower than unity suggest that rate-limiting step is particle diffusion process and the effect of re-crystallization can be neglected. The self-diffusion coefficients calculated using both Paterson's and Nernst-Plank approximations are increased by the temperature. The observed values for isotope exchange characteristics such as exchange fractions, exchanging amounts and fractional attainment of equilibrium are consistent with those of their calculated values. Activation energy and thermodynamic parameters calculated based on transition state theory indicate the existence of both energy and entropy barrier in the system. (orig.)

Kinetics of isotopic exchange between calcium molybdate and molybdate ions in aqueous solution

International Nuclear Information System (INIS)

Atun, G.; Ayar, N.; Bilgin, B.

2007-01-01

The heterogeneous isotopic anion exchange kinetics and equilibria between calcium molybdate and sodium molybdate solutions have been studied by using 99 Mo as tracer in batch experiments. The values of exchange ratio lower than unity suggest that rate-limiting step is particle diffusion process and the effect of re-crystallization can be neglected. The self-diffusion coefficients calculated using both Paterson's and Nernst-Plank approximations are increased by the temperature. The observed values for isotope exchange characteristics such as exchange fractions, exchanging amounts and fractional attainment of equilibrium are consistent with those of their calculated values. Activation energy and thermodynamic parameters calculated based on transition state theory indicate the existence of both energy and entropy barrier in the system. (orig.)

Real-time hydrogen/deuterium exchange kinetics via supercharged electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Sterling, Harry J; Williams, Evan R

2010-11-01

Amide hydrogen/deuterium exchange (HDX) rate constants of bovine ubiquitin in an ammonium acetate solution containing 1% of the electrospray ionization (ESI) "supercharging" reagent m-nitrobenzyl alcohol (m-NBA) were obtained using top-down, electron transfer dissociation (ETD) tandem mass spectrometry (MS). The supercharging reagent replaces the acid and temperature "quench" step in the conventional MS approach to HDX experiments by causing rapid protein denaturation to occur in the ESI droplet. The higher charge state ions that are produced with m-NBA are more unfolded, as measured by ion mobility, and result in higher fragmentation efficiency and higher sequence coverage with ETD. Single amino acid resolution was obtained for 44 of 72 exchangeable amide sites, and summed kinetic data were obtained for regions of the protein where adjacent fragment ions were not observed, resulting in an overall spatial resolution of 1.3 residues. Comparison of these results with previous values from NMR indicates that the supercharging reagent does not cause significant structural changes to the protein in the initial ESI solution and that scrambling or back-exchange is minimal. This new method for top-down HDX-MS enables real-time kinetic data measurements under physiological conditions, similar to those obtained using NMR, with comparable spatial resolution and significantly better sensitivity.

Ion exchange equilibrium constants

CERN Document Server

Marcus, Y

2013-01-01

Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and

Sorption of Molecular Oxygen by Metal-Ion Exchanger Nanocomposites

Science.gov (United States)

Krysanov, V. A.; Plotnikova, N. V.; Kravchenko, T. A.

2018-03-01

Kinetic features are studied of the chemisorption and reduction of molecular oxygen from water by metal-ion exchanger nanocomposites that differ in the nature of the dispersed metal and state of oxidation. In the Pd equilibrium sorption coefficient for oxygen dissolved in water ranges from 20 to 50, depending on the nature and oxidation state of the metal component.

Inter- and intra-annular proton exchange in gaseous benzylbenzenium ions (protonated diphenylmethane)

OpenAIRE

Kuck, Dietmar; Bäther, Wolfgang

1986-01-01

Two distinct proton exchange reactions occur in metastable gaseous benzylbenzenium ions, generated by isobutane chemical ionization of diphenylmethane and four deuterium-labelled analogues. Whereas the proton ring-walk at the benzenium moiety is fast giving rise to a completely random intraannular proton exchange, the interannular proton exchange is surprisingly slow and competes with the elimination of benzene. A kinetic isotope effect of kH/kD= 5 has been determined for the interannular pro...

Studies on indigenous ion exchange resins: alkali metal ions-hydrogen ion exchange equilibria

International Nuclear Information System (INIS)

Shankar, S.; Kumar, Surender; Venkataramani, B.

2001-01-01

With a view to select a suitable ion exchange resin for the removal of radionuclides (such as cesium, strontium etc.) from low level radioactive effluents, alkali metal ion -H' exchanges on nine indigenous gel- and macroporous-type and nuclear grade resins have been studied at a total ionic strength of 0.1 mol dm .3 (in the case ofCs' -H' exchange it was 0.05 mol dm .3 ). The expected theoretical capacities were not attained by all the resins for the alkali metal ions. The water content (moles/equiv.) of the fully swollen resins for different alkali metal ionic forms do not follow the usual sequence of greater the tendency of the cation to hydrate the higher the water uptake, but a reverse trend. The ion exchange isotherms (plots of equivalent fractions of the ion in resin phase, N M1 to that in solution, N M ) were not satisfactory and sorption of cations, for most of the resins, was possible only when the acidity of the solution was lowered. The variations of the selectivity coefficient, K, with N M show that the resins are highly cross linked and the selectivity sequence: Cs + >K + >Na + >Li + , obtained for all the resins indicate that hydrated ions were involved in the exchange process. However, the increase in the selectivity was not accompanied by the release of water, but unusual uptake of water, during the exchange process. The characteristics of macroporous resins were not significantly different from those of the gel-type resins. The results are discussed in terms of heterogeneity in the polymer net work, improper sulphonation process resulting in the formation of functional groups at inaccessible sites with weak acidic character and the overall lack of control in the preparation of different resins. (author)

Kinetic study of ion exchange in phosphoric acid chelating resin

International Nuclear Information System (INIS)

Brikci-Nigassa, Mounir; Hamouche, Hafida

1995-11-01

Uranium may be recovered as a by product of wet phosphoric acid using a method based on specific ion exchange resins. These resins called chelates contain amino-phosphonic functional groups. The resin studied in this work is a purolite S-940; uranium may be loaded on this resin from 30% P2O5 phosphoric acid in its reduced state. The influence of different parameters on the successive steps of the process have been studied in batch experiments: uranium reduction, loading and oxydation. Uranium may be eluted with ammonium carbonate and the resin regeneration may be done with hydrochloric acid.Ferric ions reduce the effective resin capacity considerably and inert fixation conditions are proposed to enhance uranium loading

Ion-exchange chromatographic protein refolding

NARCIS (Netherlands)

Freydell, E.; Wielen, van der L.; Eppink, M.H.M.; Ottens, M.

2010-01-01

The application of ion-exchange (IEX) chromatography to protein refolding (IExR) has been successfully proven, as supported by various studies using different model proteins, ion-exchange media and flow configurations. Ion-exchange refolding offers a relatively high degree of process

Study of the retention of radionuclides by ion-exchange resins contained in the circuits of a Pressurized Water Reactor

International Nuclear Information System (INIS)

Gressier, F.

2008-11-01

Physico-chemical quality of fluids in nuclear power plant circuits must be maintained in order to limit contamination and dose rate especially when the shutdown takes place. Nevertheless, an optimum between diminishing liquid waste and limiting solid waste production has to be reached, but at affordable costs. Ion-exchange resins of purification circuits are used to fulfill this goal. In this work, different resin types have been characterized (exchange capacity, water and electrolyte sorption) and their selectivity towards Co 2+ , Ni 2+ , Cs + and Li + cations have been studied. We have shown that the two cation-exchange resins selectivity varies according to the nature and concentrations of their counter-ions. Moreover, flow rate (and thus hydro-kinetics) impact on species retention in a column has been characterized: the more the flow rate, the more the ionic leakage (output concentration divided by input concentration) is fast and the more the output concentration front is spread. A literature revue has enabled to put in light advantages and drawbacks of the models of interest to simulate operations of ion-exchange resins. Thus, the pure end-members mixing model associated to a non-ideality description of the resin phase based on the regular solutions model has been retained for modelling ion-exchange equilibrium. Ion-exchange kinetics has been described by mass transfer coefficients. Using the experimental results to determine model parameters, these last ones have been implemented in a speciation code CHESS, coupled with a hydrodynamic code in HYTEC. On the one hand, equilibrium experiments of ion retention have been simulated and, on the other hand, column retention tests have been modelled. Finally, selectivity variations and hydro-kinetics impacts have been simulated on some test cases so as to demonstrate the importance of taking these into account when simulating ion-exchange resins operations. (author)

Ion exchange technology assessment report

International Nuclear Information System (INIS)

Duhn, E.F.

1992-01-01

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

PRTR ion exchange vault column sampling

International Nuclear Information System (INIS)

Cornwell, B.C.

1995-01-01

This report documents ion exchange column sampling and Non Destructive Assay (NDA) results from activities in 1994, for the Plutonium Recycle Test Reactor (PRTR) ion exchange vault. The objective was to obtain sufficient information to prepare disposal documentation for the ion exchange columns found in the PRTR Ion exchange vault. This activity also allowed for the monitoring of the liquid level in the lower vault. The sampling activity contained five separate activities: (1) Sampling an ion exchange column and analyzing the ion exchange media for purpose of waste disposal; (2) Gamma and neutron NDA testing on ion exchange columns located in the upper vault; (3) Lower vault liquid level measurement; (4) Radiological survey of the upper vault; and (5) Secure the vault pending waste disposal

Synthesis of Prebiotic Caramels Catalyzed by Ion-Exchange Resin Particles: Kinetic Model for the Formation of Di-d-fructose Dianhydrides.

Science.gov (United States)

Ortiz Cerda, Imelda-Elizabeth; Thammavong, Phahath; Caqueret, Vincent; Porte, Catherine; Mabille, Isabelle; Garcia Fernandez, José Manuel; Moscosa Santillan, Mario; Havet, Jean-Louis

2018-02-21

Caramel enriched in di-d-fructose dianhydrides (DFAs, a family of prebiotic cyclic fructodisaccharides) is a functional food with beneficial properties for health. The aim of this work was to study the conversion of fructose into DFAs catalyzed by acid ion-exchange resin, in order to establish a simplified mechanism of the caramelization reaction and a kinetic model for DFA formation. Batch reactor experiments were carried out in a 250 mL spherical glass flask and afforded up to 50% DFA yields. The mechanism proposed entails order 2 reactions that describe fructose conversion on DFAs or formation of byproducts such as HMF or melanoidines. A third order 1 reaction defines DFA transformation into fructosyl-DFAs or fructo-oligosaccharides. The influence of fructose concentration, resin loading and temperature was studied to calculate the kinetic parameters necessary to scale up the process.

Synthetic inorganic ion-exchange materials

International Nuclear Information System (INIS)

Abe, M.

1979-01-01

Exchange isotherms for hydrogen ion/alkali metal ions have been measured at 20 and 40 0 C, with a solution ionic strength of 0.1, in crystalline antimonic(V) acid as a cation-exchanger. The isotherms showed S-shaped curves for the systems of H + /Na + , H + /K + , H + /Rb + and H + /Cs + , but not for H + /Li + exchange. The selectivity coefficients (logarithm scale) vs equivalent fraction of alkali metal ions in the exchanger give linear functions for all systems studied. The selectivity sequences are shown. Overall and hypothetical (zero loading) thermodynamic equilibrium constants were evaluated for these ion-exchange reactions. (author)

Kinetics of exchange reaction between neodymium(3) transcyclohexanediaminetetraacetate and europium(3)- and holmium(3) aquo-ions in the H2O and D2O solutions

International Nuclear Information System (INIS)

Nikitenko, S.I.; Martynenko, L.I.; Pechurova, N.I.; Spitsyn, V.I.

1983-01-01

The exchange reaction between central ions in the NdD - Ln' 3+ systems, where Ln' 3+ is a substituting cation (Eu 3+ and Ho 3+ , D 4 =cyclohexanediaminetetraacetate) is studied and the electrophilic suhstitution mechanism is considered. To study the kinetic isotope effects, the reagents have been solVed in heavy water containing 99.9% D 2 O. The electrophilic substitution in the indicated systems proceeds through the dissociative mechanism catalyzed by protons and via the spontaneous dissociation mechanism. The exchange via the acid-catalyzed mechanism is limited by the intermediate protonated complex decay. The associative mechanism of the electrophilic exchange in the studied systems is not realized

ION EXCHANGE IN GLASS-CERAMICS

Directory of Open Access Journals (Sweden)

George Halsey Beall

2016-08-01

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

Complex ion kinetics. Reaction rates on ion-exchange resins compared to those in water

International Nuclear Information System (INIS)

Liss, I.B.; Murmann, R.K.

1975-01-01

A comparison has been made between the rates in water and on an ion-exchange resin for the aquation of [(NH 3 ) 5 CoOReO 3 ] 2+ and [(H 2 O) 5 CrCl] 2+ and for the 18 O isotopic exchange of water with [(NH 3 ) 5 Co(OH 2 )] 3+ and ReO 4 - . The rate of water exchange on [(NH 3 ) 5 Co(OH 2 )] 3+ was not changed by association with Dowex 50W resins. Aquation of [(NH 3 ) 5 CoOReO 3 ] 2+ and water exchange on ReO 4 - had modified pH dependencies when associated with a resin. With the cobalt complex the rates were faster on the resin in the acidic region and slower on the resin in the basic region. A new term in the rate equation was observed when ReO 4 - was on the resin, first order in H + , while the other terms appear to be unchanged. Aquation of [(H 2 O) 5 CrCl] 2+ was much slower when it was absorbed on the resin. This was related to the known ionic strength effect of the reaction. (auth)

Kinetics of ethylenediaminetetraacetate exchange of americium (3) with copper (2) in aqueous solution

International Nuclear Information System (INIS)

Nikitenko, S.I.; Martynenko, L.I.; Pechurova, N.I.

1985-01-01

By the method of spectrophotometry exchange kinetics in the AmA - -Cu 2+ , where A 4- -ethylenediaminetetraacetate, is studied. The values of exchange rate constants and thermodynamic activation parameters have been found. It is shown that exchange of central ions is rialized according to the dissociative mechanism with formation of intermediate protonated complexes and according to the associative mechanism with formation of binuclear intermediates. The exchange mechanisms identity for AmA - and LnA - , where Ln 3+ -RE cations of cerium subgroup is proved. It is assumed that values of activation entropy in exchange processes are determined by the radius of the leaving cation and of activation enthalpy - by the peculiarities of the electronic structure

Ion exchange phenomena

Energy Technology Data Exchange (ETDEWEB)

Bourg, I.C.; Sposito, G.

2011-05-01

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

Fundamentals of ion exchange

International Nuclear Information System (INIS)

Townsend, R.P.

1993-01-01

In this paper the fundamentals of ion exchange mechanisms and their thermodynamics are described. A range of ion exchange materials is considered and problems of communication and technology transfer between scientists working in the field are discussed. (UK)

Biodegradation of ion-exchange media

International Nuclear Information System (INIS)

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

1988-08-01

Ion-exchange media, both bead resins and powdered filter media, are used in nuclear power plants to remove radioactivity from process water prior to reuse or environmental discharge. Since the ion- exchange media are made from synthetic hydrocarbon-based polymers, they may be susceptible to damage from biological activity. The purpose of this study was to investigate some of the more basic aspects of biodegradation of ion-exchange media, specifically to evaluate the ability of microorganisms to utilize the ion-exchange media or materials sorbed on them as a food source. The ASTM-G22 test, alone and combined with the Bartha Pramer respirometric method, failed to indicate the biodegradability of the ion-exchange media. The limitation of these methods was that they used a single test organism. In later phases of this study, a mixed microbial culture was grown from resin waste samples obtained from the BNL High Flux Beam Reactor. These microorganisms were used to evaluate the susceptibility of different types of ion-exchange media to biological attack. Qualitative assessments of biodegradability were based on visual observations of culture growths. Greater susceptibility was associated with increased turbidity in solution indicative of bacterial growth, and more luxuriant fungal mycelial growth in solution or directly on the ion-exchange resin beads. 21 refs., 9 figs., 18 tabs

The isotope separation by ion exchange chromatography. Application to the lithium isotopes separation

International Nuclear Information System (INIS)

Albert, M.G.; Barre, Y.; Neige, R.

1993-01-01

In this work is described the used study step to demonstrate the industrial feasibility of a lithium isotopes separation process by ion exchange chromatography. After having recalled how is carried out the exchange reaction between the lithium isotopes bound on the cations exchanger resin and those which are in solution and gave the ion exchange chromatography principle, the authors establish a model which takes into account the cascade theory already used for enriched uranium production. The size parameters of this model are: the isotopic separation factor (which depends for lithium of the ligands nature and of the coordination factor), the isotopic exchange kinetics and the mass flow (which depends of the temperature, the lithium concentration, the resins diameter and the front advance). The way they have to be optimized and the implementation of the industrial process are given. (O.M.)

Electrically switched cesium ion exchange

International Nuclear Information System (INIS)

Lilga, M.A.; Orth, R.J.; Sukamto, J.P.H.; Schwartz, D.T.; Haight, S.M.; Genders, J.D.

1997-04-01

Electrically Switched Ion Exchange (ESIX) is a separation technology being developed as an alternative to conventional ion exchange for removing radionuclides from high-level waste. The ESIX technology, which combines ion exchange and electrochemistry, is geared toward producing electroactive films that are highly selective, regenerable, and long lasting. During the process, ion uptake and elution are controlled directly by modulating the potential of an ion exchange film that has been electrochemically deposited onto a high surface area electrode. This method adds little sodium to the waste stream and minimizes the secondary wastes associated with traditional ion exchange techniques. Development of the ESIX process is well underway for cesium removal using ferrocyanides as the electroactive films. Films having selectivity for perrhenate (a pertechnetate surrogate) over nitrate also have been deposited and tested. A case study for the KE Basin on the Hanford Site was conducted based on the results of the development testing. Engineering design baseline parameters for film deposition, film regeneration, cesium loading, and cesium elution were used for developing a conceptual system. Order of magnitude cost estimates were developed to compare with conventional ion exchange. This case study demonstrated that KE Basin wastewater could be processed continuously with minimal secondary waste and reduced associated disposal costs, as well as lower capital and labor expenditures

3.5 Radiation stability of ion exchangers

International Nuclear Information System (INIS)

Marhol, M.

1976-01-01

The main knowledge is summed up of the radiation stability of ion exchangers. No basic changes occur in inorganic ion exchangers with the exception of the exchange capacity at doses of up to 10 9 rad. This also applies to coal-based ion exchangers. Tables are given showing the changes in specific volume, exchange capacity and weight of different types of organic ion exchangers in dependence on the radiation dose. The effects are discussed of the structure of organic cation and anion exchangers, polymeric strong basic anion exchangers, polycondensate anion exchangers and ion exchange membranes on their radiation stability. General experimental procedures are given for laboratory tests of the radiation stability of exchangers. (L.K.)

Decomposing method for ion exchange resin

International Nuclear Information System (INIS)

Sako, Takeshi; Sato, Shinshi; Akai, Yoshie; Moniwa, Shinobu; Yamada, Kazuo

1998-01-01

The present invention concerns a method of decomposing ion exchange resins generated in a nuclear power plant to carbon dioxide reliably in a short period of time. (1) The ion exchange resins are mixed with water, and then they are kept for a predetermined period of time in the presence of an inert gas at high temperature and high pressure exceeding the critical point of water to decompose the ion exchange resins. (2) The ion exchange resins is mixed with water, an oxidant is added and they are kept for a predetermined time in the presence of an inert gas at a high temperature and a high pressure exceeding a critical point of water of an inert gas at a high temperature to decompose the ion exchange resins. (3) An alkali or acid is added to ion exchange resins and water to control the hydrogen ion concentration in the solution and the ion exchange resins are decomposed in above-mentioned (1) or (2). Sodium hydroxide is used as the alkali and hydrochloric acid is used as the acid. In addition, oxygen, hydrogen peroxide or ozone is used as an oxidant. (I.S.)

Disposal of bead ion exchange resin wastes

International Nuclear Information System (INIS)

Gay, R.L.; Granthan, L.F.

1985-01-01

Bead ion exchange resin wastes are disposed of by a process which involves spray-drying a bead ion exchange resin waste in order to remove substantially all of the water present in such waste, including the water on the surface of the ion exchange resin beads and the water inside the ion exchange resin beads. The resulting dried ion exchange resin beads can then be solidified in a suitable solid matrix-forming material, such as a polymer, which solidifies to contain the dried ion exchange resin beads in a solid monolith suitable for disposal by burial or other conventional means

Influence of some factors on kinetics of boron ions sorption by inorganic anion exchanger of MNG type

International Nuclear Information System (INIS)

Leont'eva, G.V.

1991-01-01

Consideration is given to the influence of particle size of anion exchanger and boron ion concentration on boron sorption from the solution of the following composition (kg/m 3 ): Na + -71.3; K + - 1.9; Ca 2+ - 43.8; Mg 2+ - 5.7; B 2 O 3 -0.32-1.50; Cl - - 204.6, SO 4 2- - 0.02, CO 3 2+ - 0.40; HCO 3 - - 1.74; pH=8.1; density - 1225 kg/m 3 . Increase of dispersivity of ion-exchange material promotes the elevation of sorption rate. Increase of boron ion concentration in the solution leads to exchange capacity growth and reduction of latent period of nucleation; this results to increase of sorption rate

Novel silica-based ion exchange resin

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-11-01

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

Ion exchange behaviour of citrate and EDTA anions on strong and weak base organic ion exchangers

International Nuclear Information System (INIS)

Askarieh, M.M.; White, D.A.

1988-01-01

The exchange of citrate and EDTA ions with two strong base and two weak base exchangers is considered. Citrate and EDTA analysis for this work was performed using a colorimetric method developed here. The ions most selectively exchanged on the resins are H 2 cit - and H 2 EDTA 2- , though EDTA is generally less strongly sorbed on strong base resins. In contact with weak base resins, deprotonation of the resin occurs during ion exchange with a noticeable drop in solution pH. Although EDTA sorption can be reversed by nitric acid, citrate ions are significantly held on the resin at low pH. The exchange of citrate can be made reversible if bicarbonate is added to the initial solutions. Alkaline regeneration of exchangers loaded with EDTA proved to be very effective. (author)

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

Science.gov (United States)

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

2014-02-11

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

The study on the ion exchange behavior of metal ions using composite ion exchange resin

Energy Technology Data Exchange (ETDEWEB)

Kim, Kukki; Lee, Kunjai [Nuclear Engineering Department Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Kim, Youngkyun [Korea Institute of Nuclear Safety, Daejon (Korea, Republic of); Lee, Sangjin; Yang, Hoyeon; Ha, Jonghyun [Korea Hydro and Nuclear Power Co., Daejeon (Korea, Republic of)

2002-04-15

In this study, a series of stepwise procedures to prepare a new organic-inorganic composite magnetic resin with phenol sulphonic-formaldehyde and freshly formed iron ferrite was established, based upon wet-and-neutralization method for synthesizing iron ferrite and pearl-polymerization method for synthesizing rigid bead-type composite resin. And a separation of metal ions in the liquid radioactive waste have been performed using organic-inorganic composite magnetic resin with phenol sulphonic-formaldehyde and freshly formed iron ferrite. The PSF-F (phenol sulphonic formaldehyde-iron ferrite) composite resin prepared by the above method shows stably high removal efficiency to Co(II), Fe, Cs species from wastewater in a wide range of solution pH. The wide range of applicable solution pH (i. e. pH 4.0 to 10.3) implies that the PSF-F composite resin overcomes the limitations of the conventional ferrite process which is practically applicable only to alkaline conditions. The experiment proceeded using batch reactor in a constant temperature with water bath. The experiments divided into three parts. The first one is TG/DTA (Thermogravimetry / Differential Thermal Analysis) which can analyze the trend of pyrolysis of PSF-F ion exchanger. The Second one is equilibrium experiment in which the separation factor of metal ions and Langmuir, Freundlich isotherm was achieved. The last one is kinetics experiment in which the equilibrium reaction time and removal efficiency is estimated.

The study on the ion exchange behavior of metal ions using composite ion exchange resin

International Nuclear Information System (INIS)

Kim, Kukki; Lee, Kunjai; Kim, Youngkyun; Lee, Sangjin; Yang, Hoyeon; Ha, Jonghyun

2002-01-01

In this study, a series of stepwise procedures to prepare a new organic-inorganic composite magnetic resin with phenol sulphonic-formaldehyde and freshly formed iron ferrite was established, based upon wet-and-neutralization method for synthesizing iron ferrite and pearl-polymerization method for synthesizing rigid bead-type composite resin. And a separation of metal ions in the liquid radioactive waste have been performed using organic-inorganic composite magnetic resin with phenol sulphonic-formaldehyde and freshly formed iron ferrite. The PSF-F (phenol sulphonic formaldehyde-iron ferrite) composite resin prepared by the above method shows stably high removal efficiency to Co(II), Fe, Cs species from wastewater in a wide range of solution pH. The wide range of applicable solution pH (i. e. pH 4.0 to 10.3) implies that the PSF-F composite resin overcomes the limitations of the conventional ferrite process which is practically applicable only to alkaline conditions. The experiment proceeded using batch reactor in a constant temperature with water bath. The experiments divided into three parts. The first one is TG/DTA (Thermogravimetry / Differential Thermal Analysis) which can analyze the trend of pyrolysis of PSF-F ion exchanger. The Second one is equilibrium experiment in which the separation factor of metal ions and Langmuir, Freundlich isotherm was achieved. The last one is kinetics experiment in which the equilibrium reaction time and removal efficiency is estimated

Study of mineral ion exchangers for strontium removal from nuclear waste waters

International Nuclear Information System (INIS)

Merceille, A.

2012-01-01

The problems of chemical pollution of water have become a major concern and a priority for the nuclear industry. The aim of this work is to study some ion exchangers used for the removal of strontium ions because 90 Sr is one of a major pollutant in nuclear liquid wastes. This study allows linking the physical and chemical properties of these materials and their sorption properties. This work presents therefore the synthesis of two materials - sodium nona-titanate and zeolite A - selected for their specific sorption properties of strontium: A second part of this work is dedicated to the study of specific exchange capacities of these materials for the strontium in presence of other elements such as sodium and calcium. Batch experiments were performed and kinetic and ion exchange models have been applied to understand the selectivity of the materials for strontium removal. Sodium nona-titanate and zeolite A are also studied in actual effluents. Monoliths of zeolite A have been also tested in dynamic ion exchange process. This material is promising for the treatment of radioactive effluents in continuous flow because it joins the sorption properties of the zeolite powder with the advantage of a solid with a macroporous network. (author) [fr

Application of ion exchange processes for the treatment of radioactive waste and management of spent ion exchangers

International Nuclear Information System (INIS)

2002-01-01

This report describes the ion exchange technologies currently used and under development in nuclear industry, in particular for waste management practices, along with the experience gained in their application and with the subsequent handling, treatment and conditioning of spent ion exchange media for long term storage and/or disposal. The increased role of inorganic ion exchangers for treatment of radioactive liquid waste, both in nuclear power plant operations and in the fuel reprocessing sector, is recognised in this report. The intention of this report is to consolidate the previous publications, document recent developments and describe the state of the art in the application of ion exchange processes for the treatment of radioactive liquid waste and the management of spent ion exchange materials

Working-state Morphologies of Ion Exchange Catalysts and Their Influence on Reaction Kinetics

Czech Academy of Sciences Publication Activity Database

Jeřábek, Karel; Hanková, Libuše; Holub, Ladislav

2010-01-01

Roč. 333, 1-2 (2010), s. 109-113 ISSN 1381-1169 Grant - others:DCH(US) BD20 Institutional research plan: CEZ:AV0Z40720504 Keywords : ion exchanger catalyst * morphology * esterification Subject RIV: CC - Organic Chemistry Impact factor: 2.872, year: 2010

Lithium-sodium separation by ion-exchange. Particular study of a pulsed column

International Nuclear Information System (INIS)

Auvert, H.

1966-02-01

A study is made of the operational conditions and constraints in the case of a moving-bed ion-exchange column subjected to pulses. The example chosen to illustrate its application concerns the lithium-sodium separation in a hydroxide medium (LiOH, NaOH). In the first part, the physico-chemical characteristics of the exchange and the kinetic characteristics of the exchange-reaction are considered. In the second part, the operation of the pulsed column is studied. Using the results obtained in the first part, the conditions required for study state operation are determined. When this is obtained, it is possible to calculate the height equivalent of the theoretical plate (HETP) of the installation. A study is also made of 'sliding', a phenomenon peculiar to pulsed columns. The results obtained show that it is possible, using laboratory tests, to determine the characteristics and the operational condition of a moving-bed ion-exchange column. (author) [fr

Exercise: Kinetic considerations for gas exchange.

Science.gov (United States)

Rossiter, Harry B

2011-01-01

The activities of daily living typically occur at metabolic rates below the maximum rate of aerobic energy production. Such activity is characteristic of the nonsteady state, where energy demands, and consequential physiological responses, are in constant flux. The dynamics of the integrated physiological processes during these activities determine the degree to which exercise can be supported through rates of O₂ utilization and CO₂ clearance appropriate for their demands and, as such, provide a physiological framework for the notion of exercise intensity. The rate at which O₂ exchange responds to meet the changing energy demands of exercise--its kinetics--is dependent on the ability of the pulmonary, circulatory, and muscle bioenergetic systems to respond appropriately. Slow response kinetics in pulmonary O₂ uptake predispose toward a greater necessity for substrate-level energy supply, processes that are limited in their capacity, challenge system homeostasis and hence contribute to exercise intolerance. This review provides a physiological systems perspective of pulmonary gas exchange kinetics: from an integrative view on the control of muscle oxygen consumption kinetics to the dissociation of cellular respiration from its pulmonary expression by the circulatory dynamics and the gas capacitance of the lungs, blood, and tissues. The intensity dependence of gas exchange kinetics is discussed in relation to constant, intermittent, and ramped work rate changes. The influence of heterogeneity in the kinetic matching of O₂ delivery to utilization is presented in reference to exercise tolerance in endurance-trained athletes, the elderly, and patients with chronic heart or lung disease. © 2011 American Physiological Society.

Removal of some heavy metals from industrial waste water using polyacrylamide ferric antimonate as new ion exchange material

International Nuclear Information System (INIS)

El-Aryan, Y.F.A.

2011-01-01

Composite ion exchangers consist of one or more ion exchangers combined with another material, which can be inorganic or organic and may it be an ion exchanger. The reason for manufacturing a composite material is to produce a granular material, with sufficient strength for column use, from ion exchangers that do not form, or only form weak, granules themselves. Attempts in this study are focused to prepare composite ion exchangers for treatment of wastewater. Heavy metals when present in water in concentrations exceeding the permitted limits are injurious to the health. Hence, it is very important to treat such waters to remove the metal ions present before it is supplied for any useful purpose. Therefore, many investigations have studied to develop more effective process to treat such waste stream. Ion-exchange has been widely adopted in heavy metal containing wastewater and most of the ion-exchangers (i.e. ion-exchange media) currently being used are commercially mass-produced organic resins.Therefore, the main aim of this work is directed to find the optimum conditions for removal of some heavy metals from industrial waste water.1-Preparation of polyacrylamide ferric antimonate composite.2-Characterization of the prepared exchanger using IR spectra, X-ray diffraction pattern, DTA and TG analyses.3-Chemical stability, capacity and equilibrium measurements will be determined on the materials using at different conditions (ph heating temperature and reaction temperature).4-Kinetic studies of some heavy metals.5-Ion exchange isotherm.6-Breakthrough curves for removal of the investigated metal ions on the prepared exchanger under certain condition.

Esterification of Palmitic Acid with Methanol in the Presence of Macroporous Ion Exchange Resin as Catalyst

Directory of Open Access Journals (Sweden)

Amelia Qarina Yaakob and Subhash Bhatia

2012-10-01

Full Text Available The esterification of palmitic acid with methanol was studied in a batch reactor using macro porous ion exchange resin Amberlyst 15 as a catalyst. Methyl palmitate was produced from the reaction between palmitic acid and methanol in the presence of catalyst. The effects of processing parameters, molar ratio of alcohol to acid M, (4-10, catalyst loading (0-10 g cat/liter, water inhibition (0-2 mol/liter, agitator speed (200-800 rpm and reaction temperature (343-373K were studied. The experimental kinetic data were correlated using homogenous as well as heterogeneous models (based on single as well as dual site mechanisms. The activation energy of the reaction was 11.552 kJ/mol for forward reaction whilst 5.464 kJ/mol for backward reaction. The experimental data fitted well with the simulated data obtained from the kinetic models. Keywords: Palmitic Acid, Methanol, Esterification, Ion Exchange Resin, Kinetics.

Ion exchange process: History, evolution and applications

International Nuclear Information System (INIS)

Mazzoldi, P.; Carturan, S.; Sada, C.; Quaranta, A.; Sglavo, V.M.

2013-01-01

The aim of this paper is to present a review on some aspects and applications of ion exchange process in glasses, ferroelectric and polymers in the fields of optics, nanotechnology, gas sensors and chemical strengthening. The formation of nanoparticles in ion-exchanged glasses, as effect of ion or laser irradiation, is discussed. A discussion on the potentialities of ion exchange process in comparison to ion implantation in optical devices and nanotechnology is also introduced. Analytical techniques applied to the study of the ion exchange process are illustrated. The studies of ion exchange process in “Natural materials” constitute the content of a specific paragraph, for applications in water cleaning. Some initial considerations on the “old age” of this technique are introduced.

Ion exchange removal of chromium (iii) from tannery wastes by using a strong acid cation exchange resin amberlite ir-120 h+ and its hybrids

International Nuclear Information System (INIS)

Ahmad, T.

2014-01-01

A strong acid cation exchange resin Amberlite IR-120 H+ and its hybrids with Mn(OH)/sub 2/, Cu(OH)/sub 2/ and Fe(OH)/sub 3/ are used for the removal of chromium (III) from spent tannery bath. The experimental data give good fits with the Langmuir sorption model. The thermodynamic parameters entropy (delta S), enthalpy (delta H) and free energy (delta G) changes are computed, which reveal that the chromium removal from tannery wastes by ion exchangers is an endothermic, physical sorption and entropically driven process. The rate of sorption is found to increase with the increase of resin dosage, stirring speed and temperature. Different kinetic models such as film diffusion, particle diffusion and Lagergren pseudo first order are used to evaluate the mechanism of the process. It is found that the hybrid ion exchange resins have better removal capacity as compared to the parent ion exchanger. The increase in the removal capacity is found to be in the order of the corresponding PZC values of the hybrid ion exchangers. Further, it is suggested that the higher exchange capacity is the result of Donnan effect and specific adsorption of chromium by the oxides / hydroxides present inside the matrix of the organic cation exchanger. (author)

Kinetics of exchange reaction between neodymium(3) transcyclohexanediaminetetraacetate and europium(3)- and holmium(3) aquo-ions in the H/sub 2/O and D/sub 2/O solutions

Energy Technology Data Exchange (ETDEWEB)

Nikitenko, S.I.; Martynenko, L.I.; Pechurova, N.I.; Spitsyn, V.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

1983-10-01

The exchange reaction between central ions in the NdD/sup -/Ln'/sup 3 +/ systems, where Ln'/sup 3 +/ is a substituting cation (Eu/sup 3 +/ and Ho/sup 3 +/, D/sup 4/=cyclohexanediaminetetraacetate) is studied and the electrophilic substitution mechanism is considered. To study the kinetic isotope effects, the reagents have been solved in heavy water containing 99.9% D/sub 2/O. The electrophilic substitution in the indicated systems proceeds through the dissociative mechanism catalyzed by protons and via the spontaneous dissociation mechanism. The exchange via the acid-catalyzed mechanism is limited by the intermediate protonated complex decay. The associative mechanism of the electrophilic exchange in the studied systems is not realized.

Gadolinium-hydrogen ion exchange of zirconium phosphate

Science.gov (United States)

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

1972-01-01

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

Kinetics of boron ions sorption from solution by inorganic anion exchanger of MNH type

International Nuclear Information System (INIS)

Leont'eva, G.V.

1990-01-01

By the method of restricted volume in case of boron excess in solution kinetics of boron sorption by inorganic anion-exchanger of the composition (Mg 0.55 Ni 0.45 )(OH) 2 has been studied. The sorption was carried out from solution containing Na + , K + , Ca 2+ , Mg 2+ , Cl - , SO 4 2- , CO 3 2- , HCO 3 at 283, 293, 303 and 313 K and pH 8.1, while the density of solution was 1225 kg/m 3 . The sorption mechanism was considered. It is shown that heterogeneity of the character of kinetic curves is caused by the change in the mechanism of limiting stages of the sorption

Chemical uranium enrichment with ion exchanger

International Nuclear Information System (INIS)

Takeda, Kunihiko; Onitsuka, Hatsuki; Obanawa, Heiichiro

1991-01-01

The uranium enrichment by using ion-exchange has been studied and developed since 1972. The ion-exchange rate has been improved approx. 3000 times and the electron exchange reaction, which occurs with ion-exchange reaction, was also accelerated with catalyst. Flow disturbance in a ion-exchange column has been fully studied and the value of turbulence has been reduced to 150μm. These results allowed us to design a very fine separation column, in which about 10000 stages can be obtained even when the column is more than 1 m in diameter. In the course of the development, a self-regenerating reaction between the redox agents was discovered and incorporated into the process, and has resulted in a reduction of 70 % in the separation energy requirement. (author)

Development of composite ion exchangers and their use in treatment of liquid radioactive wastes

International Nuclear Information System (INIS)

Sebesta, F.; John, J.; Motl, A.

1997-01-01

Composite inorganic-organic absorbers represent a group of inorganic ion exchangers modified by using binding organic material for preparation of larger size particles having higher granular strength. Such modification of originally powdered or microcrystalline inorganic ion exchangers makes their application in packed beds possible. Modified polyacrylonitrile (PAN) has been used as a universal binding polymer for a number of inorganic ion exchangers. The kinetics of ion exchange and sorption capacity of such composite absorbers is not influenced by the binding polymer mentioned above. The contents of active component in composite absorber can be varied over a very broad range (5-95% of the dry weight of the composite absorber). These composite absorbers have been tested for separation and concentration of various contaminants from aqueous solutions. Their high selectivity and sorption efficiency are advantageous for treatment of various radioactive and/or industrial waste waters, removal of natural and/or artificial radionuclides and heavy or toxic metals from underground water, determination of radionuclides ( 137 Cs, 60 Co, U, Ra) in the environment, etc. Examples of some of these applications are presented in this report. (author). 21 refs, 9 figs, 10 tabs

Ion exchange in the nuclear power industry

International Nuclear Information System (INIS)

Lehto, J.

1993-01-01

Ion exchangers are used in many fields in the nuclear power industry. At nuclear power plants, organic ion exchange resins are mainly used for the removal of ionic and particulate contaminants from the primary circuit, condensate and fuel storage pond waters. Ion exchange resins are used for the solidification of low- and medium-active nuclear waste solutions. The number of applications of zeolites, and other inorganic ion exchangers, in the separation of radionuclides from nuclear waste solutions has been increasing since the 1980s. In nuclear fuel reprocessing plants, ion exchange is used for the solidification of low- and medium-active waste solutions, as well as for the partitioning of radioactive elements for further use. (Author)

Composite inorganic ion-exchangers and their applications

International Nuclear Information System (INIS)

Sebesta, F.; John, J.; Motl, A.

1998-01-01

Composite inorganic ion exchangers are described containing modified polyacrylonitrile as the binding polymer. An overview of existing composite ion exchangers is presented, and the universality and assets of the developed procedure of treatment of inorganic ion exchanger powders are highlighted. Examples of applicability of the ion exchangers to the separation and concentration of radionuclides include in particular: wastes from the operation of nuclear power plants, contaminated surface waters and ground water, high level radioactive wastes from spent fuel reprocessing, and wastewaters from uranium ore mining and milling. In addition, composite ion exchangers find use in the monitoring of contamination of the hydrosphere and the environment and in the investigation of radionuclide migration in surface waters and ground water

Adsorption on mixtures of ion exchangers

International Nuclear Information System (INIS)

Triolo, R.; Lietzke, M.H.

1979-01-01

A theoretical study has been made of adsorption on mixtures of ion exchangers. The effect of variables such as the concentration of the ion being adsorbed, the concentration of the supporting electrolyte, loading, the values of the capacities and equilibrium constants for the various exchange processes, and the fraction of each adsorber in the mixture on the observed distribution coefficient has been investigated. A computer program has been written to facilitate the calculation of distribution coefficients for the adsorption of an ion on a given mixture of ion exchangers under a specified set of conditions

Using Ion Exchange Chromatography to Separate and Quantify Complex Ions

Science.gov (United States)

Johnson, Brian J.

2014-01-01

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

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

Science.gov (United States)

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

2017-09-01

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

Inorganic ion exchangers based on manganese and potassium for recovery and removal of pollutant metals of aqueous effluents

International Nuclear Information System (INIS)

Santos, Jacinete Lima dos

2001-01-01

This work presents a study on the synthesis, characterization and ion exchange properties of inorganic ion exchangers based on manganese and potassium. The ion exchangers were synthesized by calcination of the mixture of manganese(II) oxalate and potassium oxalate and were characterized by granulometer distribution analysis, X-ray powder diffraction, infrared spectroscopy and scanning electron microscopic. From the data obtained in characterization it was observed that exist two distinguished groups of these materials. The first group belong to ion exchangers with up to 30% w/w potassium and the second group formed by the ion exchangers with more than 30% w / w of content of potassium in their compositions. The studies of adsorption of these materials showed that the adsorption of Cd 2+ is a function of the following parameters as pH, concentration of Cd 2+ , time of contact between the ion exchangers the concentration of the Cd 2+ solution and the interference of other ions like Ni 2+ . The great pH of adsorption for these materials occur in pH 9, the study of the influence of the cadmium concentration in the adsorption showed that for a group of exchangers the adsorption decreases with the increase of cadmium concentration and for the other group the adsorption increases with the increase of cadmium concentration. The kinetics of adsorption occur in a contact time between the ion exchangers and the Cd 2+ solutions relatively short, at about 15 minutes is necessary to establish the equilibrium. The presence of Ni 2+ as interfering ion decreases the adsorption of cadmium of 99,7% to 65%. These inorganic ion exchangers showed be good exchangers for Cd 2+ . (author)

Probing peptide fragment ion structures by combining sustained off-resonance collision-induced dissociation and gas-phase H/D exchange (SORI-HDX) in Fourier transform ion-cyclotron resonance (FT-ICR) instruments.

Science.gov (United States)

Somogyi, Arpád

2008-12-01

The usefulness of gas-phase H/D exchange is demonstrated to probe heterogeneous fragment and parent ion populations. Singly and multiply protonated peptides/proteins were fragmented by using sustained off-resonance irradiation collision-induced dissociation (SORI-CID). The fragments and the surviving precursor ions then all undergo H/D exchange in the gas-phase with either D(2)O or CD(3)OD under the same experimental conditions. Usually, 10 to 60 s of reaction time is adequate to monitor characteristic differences in the H/D exchange kinetic rates. These differences are then correlated to isomeric ion structures. The SORI-HDX method can be used to rapidly test fragment ion structures and provides useful insights into peptide fragmentation mechanisms.

Studies of the hydrous titanium oxide ion exchanger. 4. Rate of the isotopic exchange of sodium ions between the exchanger in the Na+ form and aqueous solution

International Nuclear Information System (INIS)

Inoue, Yasushi; Yamazaki, Hiromichi; Kasuga, Fuminori

1995-01-01

The isotopic exchange rate of Na + between hydrous titanium(IV) oxides, precipitated at pH 6 and 13, in the Na + form and aqueous solution of sodium salt was determined radiochemically. The rate in the exchanger precipitated at pH 6 is controlled by the diffusion of Na + in the exchanger particles (particle diffusion). The diffusion coefficient and its activation energy are 1.9 x 10 -11 m 2 s -1 (pH 12, 5.0degC) and 29 kJ mol -1 (pH 12), respectively. The rate in the exchanger precipitated at pH 13 is also controlled by the particle diffusion. The rate is much slower than that in the other; this can be explained by assuming the existence of two kinds of independently diffusing ions (fast and slow species) in the exchanger. The diffusion coefficients are of the order of 10 -12 and 10 -13 m 2 s -1 for the fast and the slow species, respectively. Their activation energies are 48-60 kJ mol -1 at pH 12. The marked difference in kinetics between two exchanges was interpreted in terms of the difference in the acid-base property and in the microstructure of the matrix. (author)

Method of pyrolysis for spent ion-exchange resins

International Nuclear Information System (INIS)

Aoyama, Yoshiyuki; Matsuda, Masami; Kawamura, Fumio; Yusa, Hideo.

1985-01-01

Purpose: To prevent the generation of noxious sulfur oxide and ammonia on the pyrolysis for spent ion-exchange resins discharged from nuclear power plants. Method: In the case where the pyrolysis is made for the cationic exchange resins having sulfonic acids as the ion-exchange group, alkali metals or alkaline earth metals capable of reacting with sulfonic acid groups to form solid sulfates are previously deposited by way of ion-exchange reactions prior to the pyrolysis. In another case of the anionic exchange resins having quarternary ammonium groups as the ion-exchange groups, halogenic elements capable of reacting with the ammonium groups to form solid ammonium salts are deposited to the ion-exchange resins through ion-exchange reactions prior to the pyrolysis. As a result, the amount of the binders used can be reduced, and this method can be used in a relatively simple processing facility. (Horiuchi, T.)

Ion exchange : principles and applications

International Nuclear Information System (INIS)

Bank, Nader; Majumdar, A.S.

1975-01-01

An attempt is made to provide a brief state-of-the-art review of the basic principles underlying the unit operation of ion exchange and its numerous and diverse commercial applications. A selective bibliography is provided for the benefit of the reader interested in pursuing any specific aspect of ion exchange. (author)

Kinetic equation of heterogeneous catalytic isotope exchange

Energy Technology Data Exchange (ETDEWEB)

Trokhimets, A I [AN Belorusskoj SSR, Minsk. Inst. Fiziko-Organicheskoj Khimii

1979-12-01

A kinetic equation is derived for the bimolecular isotope exchange reaction between AXsub(n)sup(*) and BXsub(m)sup(o), all atoms of element X in each molecule being equivalent. The equation can be generalized for homogeneous and heterogeneous catalytic isotope exchange.

Recovery of tretrachloroaurate through ion exchange with Dowex 11 resin

International Nuclear Information System (INIS)

Alguacil, F.J.

1998-01-01

The recovery of the tretrachloroaurate complex by the anionic ion exchange resin Dowex 11 has been studied. The kinetics of gold adsorption were dependent of both gold and resin concentrations and temperature. The adsorption isotherm can be described by the expression Q=kC''n. The loaded resin could be eluted by an acidic thiourea solution at 20 degree centigree. After several adsorption-elution cycles there is not any apparent loss in the adsorption properties of the resin. (Author) 6 refs

225-B ion exchange piping design documentation

International Nuclear Information System (INIS)

Prather, M.C.

1996-02-01

This document describes the interface between the planned permanent ion exchange piping system and the planned portable ion exchange system. This is part of the Waste Encapsulation and Storage Facility (WESF). In order to decouple this WESF from B-Plant and to improve recovery from a capsule leak, contaminated pool cell water will be recirculated through a portable ion exchange resin system

Kinetic modeling of auroral ion outflows observed by the VISIONS sounding rocket

Science.gov (United States)

Albarran, R. M.; Zettergren, M. D.

2017-12-01

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

Fully kinetic simulation of ion acoustic and dust-ion acoustic waves

International Nuclear Information System (INIS)

Hosseini Jenab, S. M.; Kourakis, I.; Abbasi, H.

2011-01-01

A series of numerical simulations is presented, based on a recurrence-free Vlasov kinetic model using kinetic phase point trajectories. All plasma components are modeled kinetically via a Vlasov evolution equation, then coupled through Poisson's equation. The dynamics of ion acoustic waves in an electron-ion and in a dusty (electron-ion-dust) plasma configuration are investigated, focusing on wave decay due to Landau damping and, in particular, on the parametric dependence of the damping rate on the dust concentration and on the electron-to-ion temperature ratio. In the absence of dust, the occurrence of damping was observed, as expected, and its dependence to the relative magnitude of the electron vs ion temperature(s) was investigated. When present, the dust component influences the charge balance, enabling dust-ion acoustic waves to survive Landau damping even in the extreme regime where T e ≅ T i . The Landau damping rate is shown to be minimized for a strong dust concentration or/and for a high value of the electron-to-ion temperature ratio. Our results confirm earlier theoretical considerations and contribute to the interpretation of experimental observations of dust-ion acoustic wave characteristics.

Porous solid ion exchange wafer for immobilizing biomolecules

Science.gov (United States)

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

2007-12-11

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

Kinetics of zinc uptake and exchange by primary cultures of rat hepatocytes

International Nuclear Information System (INIS)

Pattison, S.E.; Cousins, R.J.

1986-01-01

The kinetics of 65 Zn 2+ uptake and exchange by hepatocytes in primary culture have been examined in detail to provide a basis for analyzing hormonal regulation of hepatic zinc metabolism. 65 Zn 2+ uptake was found to be a biphasic process. The slow phase represents an exchange between Zn 2+ in the medium and preexisting, intracellular zinc pools. This exchange rate was saturable with a medium zinc concentration of 9.5 microM eliciting one-half the maximum exchange rate and a maximum exchange rate of 9.9 pmol Zn 2+ . min-1 . mg protein-1 in the presence of bovine serum albumin. In the absence of albumin, a secondary, nonsaturable uptake rate was observed. The slow phase was relatively selective, and of the divalent transition metal ions tested, only Cd 2+ and Mn 2+ caused inhibition. The rate of exchange suggests total hepatocyte zinc has a turnover rate of approximately 30 h. The fast phase of 65 Zn 2+ reflects net Zn 2+ accumulation into a labile pool. The initial rates for this process were too fast to be measured accurately, but steady-state measurements allowed determination of the labile pool size. The pool dimensions saturated in the presence [Kapp = 28.6 microM; pool capacity = 0.44 nmol Zn 2+ /mg protein] and absence [Kapp = 11.8 microM; pool capacity = 0.34 nmol Zn 2+ /mg protein] of bovine serum albumin. Kinetics and equilibria of Zn 2+ uptake into the labile pool suggest that the latter acts as a source of Zn 2+ for the slow-exchange phase. Dexamethasone stimulated slow Zn 2+ exchange and also increased the labile pool size. The data suggest physiological factors alter hepatic zinc metabolism by influencing both intracellular Zn 2+ pools

The ion exchange and its connection the industry II.- Calculation methods for installations

International Nuclear Information System (INIS)

Uriarte Hueda, A.; Lopez Perez, B.; Gutierrez Jodra, L.

1960-01-01

An exposure is made of calculation methods for ion exchange installations based on kinetic considerations and similarity with other unitary operations. Factors to be experimentally obtained as well as difficulties which may occur in its determination are also given. Calculation procedures most commonly used in industry are enclosed and explained with numerical resolution of a problem of water demineralization. (Author) 22 refs

Control of DNA strand displacement kinetics using toehold exchange.

Science.gov (United States)

Zhang, David Yu; Winfree, Erik

2009-12-02

DNA is increasingly being used as the engineering material of choice for the construction of nanoscale circuits, structures, and motors. Many of these enzyme-free constructions function by DNA strand displacement reactions. The kinetics of strand displacement can be modulated by toeholds, short single-stranded segments of DNA that colocalize reactant DNA molecules. Recently, the toehold exchange process was introduced as a method for designing fast and reversible strand displacement reactions. Here, we characterize the kinetics of DNA toehold exchange and model it as a three-step process. This model is simple and quantitatively predicts the kinetics of 85 different strand displacement reactions from the DNA sequences. Furthermore, we use toehold exchange to construct a simple catalytic reaction. This work improves the understanding of the kinetics of nucleic acid reactions and will be useful in the rational design of dynamic DNA and RNA circuits and nanodevices.

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

International Nuclear Information System (INIS)

Ramsey, A.A.; Thorson, M.R.

2010-01-01

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.

Progress in liquid ion exchangers

International Nuclear Information System (INIS)

Nakagawa, Genkichi

1974-01-01

Review is made on the extraction with anion exchangers and the extraction with liquid cation exchangers. On the former, explanation is made on the extraction of acids, the relation between anion exchange and the extraction of metals, the composition of the metallic complexes that are extracted, and the application of the extraction with anion exchangers to analytical chemistry. On the latter, explanation is made on the extraction of metals and its application to analytical chemistry. The extraction with liquid ion exchangers is suitable for the operation in chromatography, because the distribution of extracting agents into aqueous phase is small, and extraction equilibrium is quickly reached, usually within 1 to several minutes. The separation by means of anion exchangers is usually made from hydrochloric acid solution. For example, Brinkman et al. determined Rf values for more than 50 elements by thin layer chromatography. Tables are given for showing the structure of the liquid ion exchangers and the polymerized state of various amines. (Mori, K.)

Crystalline silicotitanates -- novel commercial cesium ion exchangers

International Nuclear Information System (INIS)

Braun, R.; Dangieri, T.J.; Fennelly, D.J.

1996-01-01

A new class of inorganic ion exchangers called crystalline silicotitanates (CST), invented by researchers at Sandia National Laboratories and Texas A ampersand M University, has been commercialized in a joint Sandia-UOP effort. The original developmental materials exhibited high selectivity for the ion exchange of cesium, strontium, and several other radionuclides from highly alkaline solutions containing molar concentrations of Na + . The materials also showed excellent chemical and radiation stability. These CST properties made them excellent candidates for treatment of solutions such as the Hanford tank supernates and other DOE radwastes. Sandia and UOP, under a Cooperative Research and Development Agreement (CRADA), developed CSTs in the powdered form and in an engineered form suitable for column ion exchange use. A continuous-flow, column ion exchange process is expected to be used to remove Cs and other radionuclides from the Hanford supernatant. The powder material invented by Sandia and Texas A ampersand M consists of submicron-size particles. It is not designed for column ion exchange but may be used in other applications such as batch waste processing. Data are also presented confirming the excellent stability of the commercial CSTs over a broad pH range and the high radiation stability of the exchangers. In addition, data are provided that demonstrate the high physical strength and attrition resistance of IONSIV reg-sign IE-911, critical properties for column ion exchange applications

Method of burning ion-exchange resin contaminated with radioactivity

International Nuclear Information System (INIS)

Suzuki, Shigenori.

1986-01-01

Purpose: To process spent ion exchange resins to reduce their volume, without increasing the load on a off-gas system and in a stable state and at the same time not leaving any uncombusted portions. Method: The water slurries of the ion exchange resins contaminated with radioactive materials is dehydrated or dry combusted to reduce the water content. A binder is then added to solidify the ion exchange resin. The solidified ion exchange resins are then combusted in a furnace. This prevents the ion exchange resin from being dispersed by air and combustion gases. Furthermore, the solidified ion exchange resins in the form of small pellets burn from the surface inwards. Moreover the binder is carbonized by the combustion heat and promotes combustion to convert the ion exchange resins into a solid mass, making sure that no uncombusted portion is left. (Takahashi, M.)

Ion exchange in ultramarine blue. Studies using radioactive tracers (1963)

International Nuclear Information System (INIS)

Goenvec, H.

1963-05-01

A study has been made of the exchange reaction between the constituent sodium in ultramarine blue, and silver in the form of a silver nitrate solution; an attempt hat been made to define the influence of the solvent of the silver nitrate on the kinetics of the exchange reaction. Five solvents have been used: water, methanol, ethanol, n-propanol and acetone. The reaction rates are controlled by a diffusion process inside the ultramarine grains, whatever the solvent used. It seems that the solvated ionic radius of the diffusing ion is one of the factors influencing the rate of reaction. Furthermore, the solvated ionic radius varies with temperature; this variation is different for each solvent and should explain the differences observed in the activation energies. (author) [fr

Kinetic Study of Esterification of Acetic Acid with n-butanol and isobutanol Catalyzed by Ion Exchange Resin

Directory of Open Access Journals (Sweden)

Amrit Pal Toor

2011-05-01

Full Text Available Esters are an important pharmaceutical intermediates and very useful perfumery agents. In this study the esterification of acetic acid with n-butanol and iso-butanol over an acidic cation exchange resin, Amberlyst 15 were carried out. The effects of certain parameters such as temperature, catalyst loading, initial molar ratio between reactants on the rate of reaction were studied. The experiments were conducted in a stirred batch reactor in the temperature range of 351.15 K to 366.15K.Variation of parameters on rate of reaction demonstrated that the reaction was intrinsically controlled.The activation energy for the esterification of acetic acid with n-butanol and iso butanol is found to be 28.45 k J/mol and 23.29 kJ/mol respectively. ©2011 BCREC UNDIP. All rights reserved.(Received: 16th December 2010, Revised: 19th March 2011; Accepted: 7th April 2011[How to Cite: A.P. Toor, M. Sharma, G. Kumar, and R. K. Wanchoo. (2011. Kinetic Study of Esterification of Acetic Acid with n-butanol and isobutanol Catalyzed by Ion Exchange Resin. Bulletin of Chemical Reaction Engineering and Catalysis, 6(1: 23-30. doi:10.9767/bcrec.6.1.665.23-30][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.665.23-30 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/665 ] | View in 

Kinetics of solid-phase in ion exchange on tin hydrogen phosphate

International Nuclear Information System (INIS)

Kislitsyn, M.N.; Ketsko, V.A.; Yaroslavtsev, A.B.

2004-01-01

Solid state reactions in mixture of tin hydrogen phosphate and alkali metal (M=Na, K, Cs) chlorides have been studied both in the mode of polythermal heating and at a fixed temperature, using data of X-ray phase and thermogravimetric analyses. In the range 400-750 Deg C solid state ion exchange reactions occur in the systems studied and yield mono-- and dialkali phosphates MHSn(PO 4 ) 2 and M 2 Sn(PO 4 ) 2 . Counter diffusion coefficients for alkali metal cations and protons in the matrices of compositions MHSn(PO 4 ) 2 and M 2 Sn(PO 4 ) 2 have been determined [ru

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

Science.gov (United States)

Sharma, S D; Gupta, R

2000-02-01

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

Exchange of Th, U and Pu on macroporous ion exchange resins

International Nuclear Information System (INIS)

Nadkarni, M.N.; Mayankutty, P.C.; Pillai, N.S.; Shinde, S.S.

1977-01-01

Absorption of Th, U and Pu on macroporous ion exchangers, Amberlyst 15 (cationic) and Amberlyst A-26 (anionic) were studied in nitric acid solutions and the results were found comparable with those on their microreticular counter parts, Dowex 50x8 and Dowex IX4. With a view to evalute the efficiency of Amberlyst A-26 for the final purification of plutonium from the purex process stream, detailed studies conducted to determine the breakthrough capacity of Pu(IV) from 7.2 M nitric acid, elution by 0.5 M nitric acid and the decontamination factors for uranium and zirconium-95. Because of its faster kinetics, Amberlyst A-26 exhibited a much more efficient elution of Pu(IV) by 0.5 M nitric acid than Dowex IX4. (author)

Organic decontamination by ion exchange

International Nuclear Information System (INIS)

Wilson, T.R.

1994-01-01

This study has successfully identified ion exchanger media suitable for decontaminating the 5500-gallon organic layer in Tank 241-C-103. Decontamination of radionuclides is necessary to meet shipping, incinerator site storage, and incineration feed requirements. The exchanger media were identified through a literature search and experiments at the Russian Institute for Physical Chemistry. The principal radionuclides addressed are Cs-137 and Sr-90. Recommendations for an experimental program plan conclude the discussion. The experimental program would provide the data necessary for plant design specifications for a column and for ion exchange media to be used in decontaminating the organic layer

21 CFR 173.21 - Perfluorinated ion exchange membranes.

Science.gov (United States)

2010-04-01

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

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

International Nuclear Information System (INIS)

Hassan, N.M.

2000-01-01

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

Ion exchange in the nuclear industry

International Nuclear Information System (INIS)

Bibler, J.P.

1990-01-01

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

Study of the retention of radionuclides by ion-exchange resins contained in the circuits of a Pressurized Water Reactor; Etude de la retention des radionucleides dans les resines echangeuses d'ions des circuits d'une centrale nucleaire a eau sous pression

Energy Technology Data Exchange (ETDEWEB)

Gressier, F.

2008-11-15

Physico-chemical quality of fluids in nuclear power plant circuits must be maintained in order to limit contamination and dose rate especially when the shutdown takes place. Nevertheless, an optimum between diminishing liquid waste and limiting solid waste production has to be reached, but at affordable costs. Ion-exchange resins of purification circuits are used to fulfill this goal. In this work, different resin types have been characterized (exchange capacity, water and electrolyte sorption) and their selectivity towards Co{sup 2+}, Ni{sup 2+}, Cs{sup +} and Li{sup +} cations have been studied. We have shown that the two cation-exchange resins selectivity varies according to the nature and concentrations of their counter-ions. Moreover, flow rate (and thus hydro-kinetics) impact on species retention in a column has been characterized: the more the flow rate, the more the ionic leakage (output concentration divided by input concentration) is fast and the more the output concentration front is spread. A literature revue has enabled to put in light advantages and drawbacks of the models of interest to simulate operations of ion-exchange resins. Thus, the pure end-members mixing model associated to a non-ideality description of the resin phase based on the regular solutions model has been retained for modelling ion-exchange equilibrium. Ion-exchange kinetics has been described by mass transfer coefficients. Using the experimental results to determine model parameters, these last ones have been implemented in a speciation code CHESS, coupled with a hydrodynamic code in HYTEC. On the one hand, equilibrium experiments of ion retention have been simulated and, on the other hand, column retention tests have been modelled. Finally, selectivity variations and hydro-kinetics impacts have been simulated on some test cases so as to demonstrate the importance of taking these into account when simulating ion-exchange resins operations. (author)

Ion exchange/adsorbent pilot plant

International Nuclear Information System (INIS)

Anon.

1982-01-01

A decontamination of greater than 99% of the actinides and fission products contained in radioactive waste water can be obtained using ion exchange resins. A system for achieving this result is described in this paper. This ion exchange pilot-plant design is the culmination of five years of study of the decontamination of radioactive waste streams by ion exchange resins and other adsorbents at Mound. In order to maintain maximum flexibility of treatments, this pilot-plant design is a conceptual design with specific flows, resins, and column specifications, but with many optional features and no rigid equipment specifications. This flexibility allows the system to be amenable to almost any radioactive waste stream. Very specific designs can be constructed from this conceptual design for the treatment of any specific waste stream. Operating and capital costs are also discussed. 1 figure, 5 tables

Method of processing spent ion exchange resins

International Nuclear Information System (INIS)

Mori, Kazuhide; Tamada, Shin; Kikuchi, Makoto; Matsuda, Masami; Aoyama, Yoshiyuki.

1985-01-01

Purpose: To decrease the amount of radioactive spent ion exchange resins generated from nuclear power plants, etc and process them into stable inorganic compounds through heat decomposition. Method: Spent ion exchange resins are heat-decomposed in an inert atmosphere to selectively decompose only ion exchange groups in the preceeding step while high molecular skeltons are completely heat-decomposed in an oxidizing atmosphere in the succeeding step. In this way, gaseous sulfur oxides and nitrogen oxides are generated in the preceeding step, while gaseous carbon dioxide and hydrogen requiring no discharge gas procession are generated in the succeeding step. Accordingly, the amount of discharged gases requiring procession can significantly be reduced, as well as the residues can be converted into stable inorganic compounds. Further, if transition metals are ionically adsorbed as the catalyst to the ion exchange resins, the ion exchange groups are decomposed at 130 - 300 0 C, while the high molecular skeltons are thermally decomposed at 240 - 300 0 C. Thus, the temperature for the heat decomposition can be lowered to prevent the degradation of the reactor materials. (Kawakami, Y.)

Li+ solvation and kinetics of Li+-BF4-/PF6- ion pairs in ethylene carbonate. A molecular dynamics study with classical rate theories

Science.gov (United States)

Chang, Tsun-Mei; Dang, Liem X.

2017-10-01

Using our polarizable force-field models and employing classical rate theories of chemical reactions, we examine the ethylene carbonate (EC) exchange process between the first and second solvation shells around Li+ and the dissociation kinetics of ion pairs Li+-[BF4] and Li+-[PF6] in this solvent. We calculate the exchange rates using transition state theory and correct them with transmission coefficients computed by the reactive flux, Impey, Madden, and McDonald approaches, and Grote-Hynes theory. We found that the residence times of EC around Li+ ions varied from 60 to 450 ps, depending on the correction method used. We found that the relaxation times changed significantly from Li+-[BF4] to Li+-[PF6] ion pairs in EC. Our results also show that, in addition to affecting the free energy of dissociation in EC, the anion type also significantly influences the dissociation kinetics of ion pairing.

Oxidation of cyclohexane catalyzed by metal-ion-exchanged zeolites.

Science.gov (United States)

Sökmen, Ilkay; Sevin, Fatma

2003-08-01

The ion-exchange rates and capacities of the zeolite NaY for the Cu(II), Co(II), and Pb(II) metal ions were investigated. Ion-exchange equilibria were achieved in approximately 72 h for all the metal ions. The maximum ion exchange of metal ions into the zeolite was found to be 120 mg Pb(II), 110 mg Cu(II), and 100 mg Co(II) per gram of zeolite NaY. It is observed that the exchange capacity of a zeolite varies with the exchanged metal ion and the amount of metal ions exchanged into zeolite decreases in the sequence Pb(II) > Cu(II) > Co(II). Application of the metal-ion-exchanged zeolites in oxidation of cyclohexane in liquid phase with visible light was examined and it is observed that the order of reactivity of the zeolites for the conversion of cyclohexane to cyclohexanone and cyclohexanol is CuY > CoY > PbY. It is found that conversion increases by increase of the empty active sites of a zeolite and the formation of cyclohexanol is favored initially, but the cyclohexanol is subsequently converted to cyclohexanone.

Ion trapping in one-minimum potentials via charge-exchange collisions

International Nuclear Information System (INIS)

Maier, H.; Kuhn, S.

1994-01-01

A (1 d, 2 v), electrostatic, kinetics model for time-independent single-ended Q-machine states with a positively biased cold plate and a single internal minimum near the hot plate is presented. While the electrons are treated as collisionless, charge-exchange collisions between the ions and the neutral background gas atoms are taken into account by means of a linearized Boltzmann collision operator. The self-consistent plasma states are found by using an iterative analytic-numerical trajectory-simulation method in which the charge-density and potential distributions are alternately determined numerical results clearly demonstrate the sensitive role that trapped ions play in shaping the microscopic and macroscopic properties of the dc states under study. The trapped-ion distributions themselves are shown to be controlled critically by the detailed scattering conditions, which in turn are determined by the choice of the background properties. (author). 10 refs, 3 figs

Rod-shaped ion exchanger useful for purifying liquids or recovering components from liquids comprises a metal wire core surrounded by an ion-exchange resin

NARCIS (Netherlands)

Koopman, C.; Witkamp, G.J.

2002-01-01

Rod-shaped ion exchanger comprises a metal wire core surrounded by an ion-exchange resin. Independent claims are also included for: (1) a module comprising a housing with an inlet and outlet and one or more ion exchangers as above; (2) a process for producing an ion exchanger as above, comprising

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

Directory of Open Access Journals (Sweden)

Supitcha Rungrodnimitchai

2014-01-01

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

Kinetics of the exchange of oxygen between carbon dioxide and carbonate in aqueous solution

International Nuclear Information System (INIS)

Tu, C.K.; Silverman, D.N.

1975-01-01

A kinetic analysis of the exchange of oxygen between carbon dioxide and carbonate ion in alkaline, aqueous solutions is presented. The exchange was observed by placing 18 O-labeled carbonate, not enriched in 13 C, into solution with 13 C-enriched carbonate, not enriched in 18 O. The rate of depletion of 18 O from the 12 C-containing species and the rate of appearance of 18 O in the 13 C-containing species was measured by mass spectrometry. From these data, the second-order rate constant for the reaction between carbon dioxide and carbonate which results in the exchange of oxygen at 25 0 is 114 +- 11 M -1 sec -1 . It is emphasized that this exchange of oxygen between species of CO 2 in solution must be recognized in studies using 18 O labels to determine the fate of CO 2 in biochemical and physiological processes. (auth)

Ion Mobility Spectrometry-Mass Spectrometry Coupled with Gas-Phase Hydrogen/Deuterium Exchange for Metabolomics Analyses

Science.gov (United States)

Maleki, Hossein; Karanji, Ahmad K.; Majuta, Sandra; Maurer, Megan M.; Valentine, Stephen J.

2018-02-01

Ion mobility spectrometry-mass spectrometry (IMS-MS) in combination with gas-phase hydrogen/deuterium exchange (HDX) and collision-induced dissociation (CID) is evaluated as an analytical method for small-molecule standard and mixture characterization. Experiments show that compound ions exhibit unique HDX reactivities that can be used to distinguish different species. Additionally, it is shown that gas-phase HDX kinetics can be exploited to provide even further distinguishing capabilities by using different partial pressures of reagent gas. The relative HDX reactivity of a wide variety of molecules is discussed in light of the various molecular structures. Additionally, hydrogen accessibility scoring (HAS) and HDX kinetics modeling of candidate ( in silico) ion structures is utilized to estimate the relative ion conformer populations giving rise to specific HDX behavior. These data interpretation methods are discussed with a focus on developing predictive tools for HDX behavior. Finally, an example is provided in which ion mobility information is supplemented with HDX reactivity data to aid identification efforts of compounds in a metabolite extract.

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

International Nuclear Information System (INIS)

Horner, D.A.

1984-08-01

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

Oxidative degradation of low and intermediate level Radioactive organic wastes 2. Acid decomposition on spent Ion-Exchange resins

Energy Technology Data Exchange (ETDEWEB)

Ghattas, N K; Eskander, S B [Radioisotope dept., atomic energy authority, (Egypt)

1995-10-01

The present work provides a simplified, effective and economic method for the chemical decomposition of radioactively contaminated solid organic waste, especially spent ion - exchange resins. The goal is to achieve volume reduction and to avoid technical problems encountered in processes used for similar purposes (incineration, pyrolysis). Factors efficiency and kinetics of the oxidation of the ion exchange resins in acid medium using hydrogen peroxide as oxidant, namely, duration of treatment and the acid to resin ratio were studied systematically on a laboratory scale. Moreover the percent composition of the off-gas evolved during the decomposition process was analysed. 3 figs., 5 tabs.

Oxidative degradation of low and intermediate level Radioactive organic wastes 2. Acid decomposition on spent Ion-Exchange resins

International Nuclear Information System (INIS)

Ghattas, N.K.; Eskander, S.B.

1995-01-01

The present work provides a simplified, effective and economic method for the chemical decomposition of radioactively contaminated solid organic waste, especially spent ion - exchange resins. The goal is to achieve volume reduction and to avoid technical problems encountered in processes used for similar purposes (incineration, pyrolysis). Factors efficiency and kinetics of the oxidation of the ion exchange resins in acid medium using hydrogen peroxide as oxidant, namely, duration of treatment and the acid to resin ratio were studied systematically on a laboratory scale. Moreover the percent composition of the off-gas evolved during the decomposition process was analysed. 3 figs., 5 tabs

Small Column Ion Exchange

International Nuclear Information System (INIS)

Huff, Thomas

2010-01-01

Small Column Ion Exchange (SCIX) leverages a suite of technologies developed by DOE across the complex to achieve lifecycle savings. Technologies are applicable to multiple sites. Early testing supported multiple sites. Balance of SRS SCIX testing supports SRS deployment. A forma Systems Engineering Evaluation (SEE) was performed and selected Small Column Ion Exchange columns containing Crystalline Silicotitanate (CST) in a 2-column lead/lag configuration. SEE considered use of Spherical Resorcinol-Formaldehyde (sRF). Advantages of approach at SRS include: (1) no new buildings, (2) low volume of Cs waste in solid form compared to aqueous strip effluent; and availability of downstream processing facilities for immediate processing of spent resin.

Kinetic energy dissipation in heavy-ion collisions

International Nuclear Information System (INIS)

Fedotov, S.I.; Jolos, R.V.; Kartavenko, V.G.

1979-01-01

Kinetic energy dissipation mechanism is considered in deep inelastic heavy-ion collisions. It is shown that the significant part of the kinetic energy loss can be explained by the excitation of the nuclear matter multipole vibrations. The main contribution of the energy dissipation is given by the time dependent heavy-ion interaction potential renormalized due to the nuclear excitations, rather than by the velocity proportional frictional forces

Composite ion-exchangers and their possible use in treatment of low/intermediate level liquid radioactive wastes

International Nuclear Information System (INIS)

Sebesta, F.; Motl, A.; John, J.

1993-01-01

A new method of preparation of composite inorganic-organic ion exchangers using modified polyacrylonitrile (PAN) as a binding polymer for the inorganic active component is described. This method enables incorporation of very fine to colloidal particles of active component in the binding polymer which increases the capacity and improves the kinetics of ion exchange of the resulting absorber. The proposed method can be applied on most of the inorganic ion exchangers known. Results of tests of some absorbers for treatment of radioactive wastes produced in the nuclear industry are given. For the removal of radiocesium from Long Term Fuel Storage Pond water at NPP Jaslovske Bohunice (Slovakia) NiFC-PAN composite ion exchanger has been tested. Excellent results have been achieved both at low and high (floating bed) flow rates in the course of treatment of up to 45,000 BV of pond water. The possibility of decreasing the total activity of the Biological Shield water from the same NPP below the 37 Bq/l discharge limit has been proved using NiFC-PAN and NaTiO-PAN composite ion exchangers. NiFC-PAN, NaTiO-PAN, MnO-PAN, M315-PAN and Na-Y-PAN composite ion exchangers were tested for removal of radiocesium, radiocobalt and radiomanganese from standard liquid radioactive wastes and concentrates from NPP Krsko, Croatia. Different combinations of absorbers have been tested for the treatment of Boron Recycle Hold-up, Waste Condensate and Waste Hold-up Tanks. Radium could be quantitatively removed from highly saline acid waste water from uranium underground leaching on Ba(Ca)SO 4 -PAN absorber

Ion-exchange properties of natural mordenite

International Nuclear Information System (INIS)

Chelishchev, N.F.; Volodin, V.F.

1977-01-01

Ion exchange properties are studied of natural mordenite Si(Al=4.75) exhibiting adequate mechanical characteristics and sufficient resistance to high temperature acids. Consideration is given to the pattern of exchange ions distribution among mordenite and chloride solutions of K, Cs, Rb, Sr. Mordenite shows sharp selectivity towards large alkali metal cations, particularly Cs + . In these processes the exchange isotherms are characterized by the constant selectivity towards a counterion. For the Sr 2+ -2Na + exchange the isotherm shows a change of selectivity after a definite counterion concentration has been reached in the solution. Correlation between the exchange thermodynamic constants makes it possible to propose the following range of mordenite selectivity towards the cations under study: Cs>Rb>K>Na>Sr

SPEEDUPtrademark ion exchange column model

International Nuclear Information System (INIS)

Hang, T.

2000-01-01

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 SpeedUptrademark 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 SuperLigtrademark ion exchange resins, once the experimental data are complete

Treatment of Soil Decontamination Solution by the Cs{sup +} Ion Selective Ion Exchange Resin

Energy Technology Data Exchange (ETDEWEB)

Won, Hui Jun; Kim, Gye Nam; Jung, Chung Hun; Oh, Won Zin [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2005-07-01

Occasionally, radioactively contaminated soils have been excavated and stored at the temporary storage facility. Cesium as a radionuclide is one of the most toxic elements and it has a long half decay life. During the operation of nuclear facility, soils near the facility would be contaminated with radioactive cesium and it will cause the deleterious effect to human body and environment. In this study, Cs{sup +} ion selective ion exchange resin was prepared by changing the functional group of commercial anion exchange resin for a ferrocyanide ion. Ion exchange capability of using the soil decontamination solution was investigated. We also performed the feasibility test of recycling the spent Cs ion selective ion exchange resin.

Poster 29. Modelling of ion exchange processes in ultrapure water

International Nuclear Information System (INIS)

Berg, A.; Torstenfelt, B.; Fejes, P.; Foutch, G.L.

1992-01-01

The ion exchange process of the Reactor Water Clean-up (RWCU) system has been studied to better use the maximum possible exchange capacity of the ion exchange resin. Laboratory data have been correlated with computer simulations of the ion exchange process. Data were correlated using a mixed-bed ion exchange model for ultralow ionic concentrations developed at Oklahoma State University. Experimental results of the ion exchange column operation in the concentration range of 10 -3 M boric acid is compared with the simulated performance predicted by the computer model. The model is found to agree reasonably well with the data. (author)

The isotope separation by ion exchange chromatography. Application to the lithium isotopes separation; La separation isotopique par chromatographie ionique

Energy Technology Data Exchange (ETDEWEB)

Albert, M G; Barre, Y; Neige, R

1994-12-31

In this work is described the used study step to demonstrate the industrial feasibility of a lithium isotopes separation process by ion exchange chromatography. After having recalled how is carried out the exchange reaction between the lithium isotopes bound on the cations exchanger resin and those which are in solution and gave the ion exchange chromatography principle, the authors establish a model which takes into account the cascade theory already used for enriched uranium production. The size parameters of this model are: the isotopic separation factor (which depends for lithium of the ligands nature and of the coordination factor), the isotopic exchange kinetics and the mass flow (which depends of the temperature, the lithium concentration, the resins diameter and the front advance). The way they have to be optimized and the implementation of the industrial process are given. (O.M.). 5 refs.

Study on actinoid isolation by antimonide ion exchanger

Energy Technology Data Exchange (ETDEWEB)

Tsuji, Masamichi [Tokyo Inst. of Tech. (Japan). Faculty of Science; Kubota, Masumitsu; Yamagishi, Isao

1996-01-01

To establish a containment of long-life nuclides and an effective reduction of waste volume is important to reduce the loadings on the natural environment. Chemical isolation of radioactive nuclides from wastes was attempted by using inorganic ion exchanger with high specificity and thermal stability. In this study, titanium antimonide was used as an ion exchanger to investigate the adsorption of trivalent metallic ions according to Kielland plot curves. When the ionic equivalent fraction (X-bar{sub M}) was around 0.005, Kielland plot curve of either of 3-valent metallic ions was bent, suggesting the exchanger had two different adsorption sites. The slope of the curve became smaller as an elevation of temperature. These results show that the ion radius was decreased resulting from partial elimination of the hydrated water of ion and thus, the steric conditions around the exchange site might be improved. (M.N.)

Ion exchange and hydrolysis reactions in zeolites

International Nuclear Information System (INIS)

Harjula, Risto.

1993-09-01

Among other uses, zeolites are efficient cation exchangers for aquatic pollution control. At present they they are mainly used in nuclear waste effluent treatment and in detergency. In the thesis, several ion exchange equilibria, important in these main fields of zeolite applications, were studied, with special emphasis on the formulation and calculation of the equilibria. The main interest was the development of thermodynamic formulations for the calculation of zeolite ion exchange equilibria in solutions of low or very low (trace) ion concentration, which are relevant for the removal of trace pollutants, such as radionuclides, from waste waters. Two groups of zeolite-cation systems were studied. First, binary Ca 2+ /Na + exchange in zeolites X and Y, which are of interest for detergency applications. Second, binary Cs + /Na + and Cs + /K + exchanges, and ternary Cs + /Na + /K + exchange in mordenite, which are important in nuclear waste effluent treatment. The thesis is based on five previous publications by author. (100 refs., 7 figs.)

Development of composite ion exchanger for separation of cesium from high level liquid waste

International Nuclear Information System (INIS)

Kumar, A.; Varshney, L.

2010-01-01

137 Cs (t 1/2 = 30 years) is one of the major radioisotope present in high level liquid waste (HLLW) generated during the reprocessing of nuclear fuel. Separation of 137 Cs from HLLW results in reduction of personal radiation exposure during the conditioning, transportation, storage and disposal. In addition, 137 Cs has enormous application as a radiation source in food preservation, sterilization of medical products, brachytherapy, blood irradiation, hygienization of sewage sludge etc. Ammonium molybdophosphate (AMP), an inorganic ion exchanger, has high selectivity and high exchange capacity for Cs. It exits as microcrystalline powder which is not amenable for column operation. ALIX is a composite material in which AMP is physically blended with inert polymeric substrate to improve its column property, exchange kinetics and increase its mechanical strength. The observed excellent properties of the composite are attributed to its engineered structure which is formed during its production. SEM analysis of ALIX shows that AMP crystals embedded in the cavities are not covered by the polymer which greatly enhances its availability for cesium exchange. The highly porous structure of the composite having 49% void volume facilitates faster kinetics of exchange of Cs from the aqueous phase and increased rate of reaction with alkali required during its dissolution

Ion-exchange concentration of inorganic anions from aqueous solution

Directory of Open Access Journals (Sweden)

L. P. Bondareva

2016-01-01

Full Text Available Monitoring of natural waters in the present time - consuming process, the accuracy of which is influenced by many factors: the composition of water, the presence of impurities and "interfering" components. The water sample preparation process includes the step of concentration and separation of ions determined. The most versatile, efficient, and frequently used method is the concentration of inorganic anions from aqueous solutions by ion exchanger, which can optimize the composition of water to the optimal for identification and quantitative determination of anions. The characteristics of sorption chloride, nitrate and sulfate ions of basic anion exchange resin AВ-17 and Purolite A430 were compared in the article. The constants of protolysis of ion exchangers both AB 17 and Purolite A430 are the same and equal 0.037 ± 0,002. The value of total capacity (POE Purolite A430 was 4.3 mmol/g, AB 17 – 3.4 mmol/g. The studied ion exchangers have the same type of ionic groups – quaternary ammonium, but their number and denotes differ. The number of quaternary ammonium groups is higher in Purolite A430, respectively the number of absorbed anions of these ion exchanger is higher. The values of dynamic exchange capacity (DOE of ion exchanger Purolite A430 is higher than these values of AB-17 and equal to 1.48 ± 0.03 mmol / dm3 for chloride ion, 1.50 ± 0.03 mmol / dm3 for nitrate ion, 1.62 ± 0.03 mmol / dm3 for sulfate ion. The values of the POE and DOE of anion-exchange resins Purolite A430 and AV-17 and the characteristics of the individual sorption of chloride, nitrate, sulfate ions showed an advantage of the Purolite for the concentrationing of anions. It is found that times of anions sorption from triple-anion solutions by Purolite A430 are significantly different for different anions, and these times are close for anion-exchanger AV-17. It proves the possibility of quantitative separation and concentration by anion-exchanger Purolite A430.

Radiation effects on ion exchange materials

Energy Technology Data Exchange (ETDEWEB)

Gangwer, T.E.; Goldstein, M.; Pillay, K.K.S.

1977-11-01

An extensive literature review and data compilation has been completed on the radiation-damage of ion exchange resins. The primary goal of the study has been to review the available literature on ion exchange materials used in, as well as those with potential for use in, the nuclear fuel and waste reprocessing areas. The physical and chemical properties of ion exchangers are reviewed. Experimental parameters useful in characterizing the effects of radiation on synthetic ion exchange resins are identified or defined. In compiling the diverse types of data, an effort was made to present the experimental data or experimentally based parameters in a format that would be useful for inter-comparing radiation effects on resins. When subject to radiation there are various general trends or qualitative effects displayed by the different types of resins. These radiation-trends and effects have been formulated into qualitative statements. The present day level of understanding of the behavior of resins under ionizing radiation is too limited to justify quantitative predictive modeling. The limitations and deficiencies of the literature are discussed and the experimentation needed to achieve quantitative modeling are outlined. 14 figs., 108 references.

Radiation effects on ion exchange materials

International Nuclear Information System (INIS)

Gangwer, T.E.; Goldstein, M.; Pillay, K.K.S.

1977-11-01

An extensive literature review and data compilation has been completed on the radiation-damage of ion exchange resins. The primary goal of the study has been to review the available literature on ion exchange materials used in, as well as those with potential for use in, the nuclear fuel and waste reprocessing areas. The physical and chemical properties of ion exchangers are reviewed. Experimental parameters useful in characterizing the effects of radiation on synthetic ion exchange resins are identified or defined. In compiling the diverse types of data, an effort was made to present the experimental data or experimentally based parameters in a format that would be useful for inter-comparing radiation effects on resins. When subject to radiation there are various general trends or qualitative effects displayed by the different types of resins. These radiation-trends and effects have been formulated into qualitative statements. The present day level of understanding of the behavior of resins under ionizing radiation is too limited to justify quantitative predictive modeling. The limitations and deficiencies of the literature are discussed and the experimentation needed to achieve quantitative modeling are outlined. 14 figs., 108 references

The Balescu kinetic equation with exchange interaction

International Nuclear Information System (INIS)

Belyi, V V; Kukharenko, Yu A

2009-01-01

Starting with the quantum BBGKY hierarchy for the distribution functions, we have obtained the quantum kinetic equation including the dynamical screening of the interaction potential, which exactly takes into account the exchange scattering in the plasma. The collision integral is expressed in terms of the Green function of the linearized Hartree–Fock equation. The potential energy takes into account the polarization and exchange interaction too

The use of chelating ion exchanger in conjunction with radioisotope X-ray spectrometry for determination of trace amounts of metals in water

International Nuclear Information System (INIS)

Holynska, B.

1974-01-01

The chelating ion exchange resin Chelex-100 has been applied for collection of trace amounts of several metal ions from water solutions. The kinetics of the exchange reaction has been measured, as well as the influence of pH of the solution and Ca or Na ion concentrations on the metal collection. The radioisotope X-ray fluorescence method has been applied for determination of metal ions absorbed in the resin. The estimated limit of determination is 0.01 ppm for Fe 3+ , Zn 2+ , Cu 2+ , Hg 2+ , Pb 2+ and Cd 2+ . Total error (1 s) of the method varied from 3 to 15% depending on the metal concentration. (author)

Kinetics of isotopic exchanges by using radioactive indicators

International Nuclear Information System (INIS)

May, S.

1958-12-01

After having noticed that iodine 131 under the form of sodium iodide has always been used as radioactive indicator in the CEA atomic pile located in Chatillon, this research report recalls the counting technique and some historical aspects of the notion of isotopic exchange and qualitative works, and presents some generalities on isotopic exchanges (reactions and calculation of rate constants of order 1 and 2, calculation of activation energy, spectro-photometric studies, Walden inversion, alkaline hydrolysis, influence of solvent on exchange kinetics, influence of the nature of the mineral halide). The author then addresses exchanges in aliphatic series (exchange with sodium iodide and with molecular iodine), exchanges in olefin series, exchanges in alicyclic series, and exchanges in aromatic series

Ion exchange fiber prepared by radiation grafting, (2)

International Nuclear Information System (INIS)

Sekiguchi, Hideaki; Fujiwara, Kunio; Fujii, Toshiaki; Takai, Takeshi; Kobayashi, Atsushi

1991-01-01

Ion exchange fiber prepared by radiation grafting has the capabilities for wide application as high performance materials. Extensive studies were made to evaluate the ion exchange fiber prepared by radiation grafting for removing some toxic or malodorous gases, continuing from the previous work (presented in Ebara Engng. Review, No. 146), in which the ability of removing ammonia with cation exchange fiber was investigated. The results of this study can be summarized by the following conclusions: (1) Methods of evaluating the ability of removing ammonia, acetaldehyde, and some lower fatty acids in low concentration were established, (2) Besides being effective for the removal of acidic or basic gases, neutral gas such as acetaldehyde can also be removed by adding some functional compounds to the ion exchange fiber, and (3) Ion exchange fiber prepared by radiation grafting is effective as a deodorizing filter. (author)

Preparation of inorganic ion exchangers with high selectivity for lithium isotopes

International Nuclear Information System (INIS)

Oi, Takao

2004-01-01

Development of ion exchangers that show large lithium isotope effects is hoped for to establish highly efficient chromatographic processes of lithium isotope separation. In this paper, preparation, characterization, ion exchange properties, and lithium isotope selectivity of inorganic materials that have been and still are being studied by my research group at Sophia University are reviewed. They include manganese oxides-based ion exchangers, antimonic acids and titanium/zirconium phosphates-based ion exchangers. As a result, the lithium isotope separation effects that were one order of magnitude larger than those of organic ion exchangers were obtained. Some inorganic ion exchangers were found to show ion exchange rates more than comparable to those of organic ones. (author)

Development of heat resistant ion exchange resin. First Report

International Nuclear Information System (INIS)

Onozuka, Teruo; Shindo, Manabu

1995-01-01

In nuclear power stations, as a means of maintaining the soundness of nuclear reactors, the cleaning of reactor cooling water has been carried out. But as for the ion exchange resin which is used as the cleaning agent in the filtrating and desalting facility in reactor water cleaning system, since the heat resistance is low, high temperature reactor water is cooled once and cleaned, therefore large heat loss occurs. If the cleaning can be done at higher temperature, the reduction of heat loss and compact cleaning facilities become possible. In this study, a new ion exchange resin having superior heat resistance has been developed, and the results of the test of evaluating the performance of the developed ion exchange resin are reported. The heat loss in reactor water cleaning system, the heat deterioration of conventional ion exchange resin, and the development of the anion exchange resin of alkyl spacer type are described. The outline of the performance evaluation test, the experimental method, and the results of the heat resistance, ion exchange characteristics and so on of C4 resin are reported. The with standable temperature of the developed anion exchange resin was estimated as 80 - 90degC. The ion exchange performance at 95degC of this resin did not change from that at low temperature in chloride ions and silica, and was equivalent to that of existing anion exchange resin. (K.I.)

Development of heat resistant ion exchange resin. First Report

Energy Technology Data Exchange (ETDEWEB)

Onozuka, Teruo; Shindo, Manabu [Tohoku Electric Power Co., Inc., Sendai (Japan)

1995-01-01

In nuclear power stations, as a means of maintaining the soundness of nuclear reactors, the cleaning of reactor cooling water has been carried out. But as for the ion exchange resin which is used as the cleaning agent in the filtrating and desalting facility in reactor water cleaning system, since the heat resistance is low, high temperature reactor water is cooled once and cleaned, therefore large heat loss occurs. If the cleaning can be done at higher temperature, the reduction of heat loss and compact cleaning facilities become possible. In this study, a new ion exchange resin having superior heat resistance has been developed, and the results of the test of evaluating the performance of the developed ion exchange resin are reported. The heat loss in reactor water cleaning system, the heat deterioration of conventional ion exchange resin, and the development of the anion exchange resin of alkyl spacer type are described. The outline of the performance evaluation test, the experimental method, and the results of the heat resistance, ion exchange characteristics and so on of C4 resin are reported. The with standable temperature of the developed anion exchange resin was estimated as 80 - 90degC. The ion exchange performance at 95degC of this resin did not change from that at low temperature in chloride ions and silica, and was equivalent to that of existing anion exchange resin. (K.I.).

The mechanism of ion exchange on ammonium 12-molybdophosphate (AMP)

International Nuclear Information System (INIS)

Boeyens, J.C.A.; McDougall, G.J.; Smit, J. van R.

1987-01-01

This paper reviews some published and unpublished data on the ion-exchange properties of AMP. The three NH 4 + ions are only partially exchanged for large monovalent ions. In the case of NH 4 + /K + exchange, the energy lost by the breaking of H bonds between the NH 4 + ions and anionic cage oxygen atoms beyond the point of maximum exchange is no longer compensated for by bond strengthening in the anion due to contraction of the cage. With Rb + , Cs + and T1 + , limited convertibility results from the lattice expansion required to accommodate these larger ions. During exchange, part of the cations pass through the anionic cages, thereby causing considerable lattice disorder. The maximum exchange capacity of AMP for the alkali metal ions is not a simple function of cation radius. (author)

Anisotropic exchange interaction for magnetic ion pairs in insulators

International Nuclear Information System (INIS)

Passeggi, M.C.G.

1975-12-01

The sources of possible contributions to the magnetic anisotropy for a pair of orbitally non degenerate magnetic ions are investigated. The problem being formulated with the help of the operator form of perturbation theory and irreducible tensor operators. Apart from the usual dipole-dipole effective interaction, mainly induced by the electronic spin-spin dipole coupling corrected by covalency, other mechanisms mediated by the spin-orbit coupling appear. These are a consequence of an appropriate description of the spin-orbit operators for a system which allows for delocalization of the magnetic electrons. A process similar to that known as pseudodipolar appears from contributions in which spin orbit combined with the Coulomb repulsion and with one-electron interactions (acting analogously as for the ''kinetic exchange'') produce compensating effects in third and fourth order, respectively. However, this effect does not appear to be describable in terms of the phenomenological exchange, as is usually assumed. (Passeggi, M.C.G.)

Kinetics of the radiation-induced exchange reactions of H2, D2, and T2: a review

International Nuclear Information System (INIS)

Pyper, J.W.; Briggs, C.K.

1978-01-01

Mixtures of H 2 --T 2 or D 2 --T 2 will exchange to produce HT or DT due to catalysis by the tritium β particle. The kinetics of the reaction D 2 + T 2 = 2DT may play an important role in designing liquid or solid targets of D 2 --DT--T 2 for implosion fusion, and distillation schemes for tritium cleanup systems in fusion reactors. Accordingly, we have critically reviewed the literature for information on the kinetics and mechanism of radiation-induced self-exchange reactions among the hydrogens. We found data for the reaction H 2 + T 2 = 2HT in the gas phase and developed a scheme based on these data to predict the halftime to equilibrium for any gaseous H 2 + T 2 mixture at ambient temperature with an accuracy of +-10 percent. The overall order of the H 2 + T 2 = 2HT reaction is 1.6 based on an initial rate treatment of the data. The most probable mechanism for radiation-induced self-exchange reaction is an ion-molecule chain mechanism

Kinetic Rate Law Parameter Measurements on a Borosilicate Waste Glass: Effect of Temperature, pH, and Solution Composition on Alkali Ion Exchange

International Nuclear Information System (INIS)

Pierce, Eric M.; McGrail, B PETER.; Icenhower, J P.; Rodriguez, Elsa A.; Steele, Jackie L.; Baum, Steven R.

2004-01-01

The reaction kinetics of glass is controlled by matrix dissolution and ion exchange (IEX). Dissolution of an alkali-rich simulated borosilicate waste glass was investigated using single-pass flow-through (SPFT) experiments. Experiments were conducted as a function of temperature, pH, and solution composition by varying the SiO 2 (aq) activity in the influent solution. Results showed that under dilute conditions matrix dissolution increased with increasing pH and temperature, and decreased with increasing SiO 2 (aq) activity. IEX rates decreased with increasing pH and temperature, and increased with increasing SiO 2 (aq) activity. Over the solution composition range interrogated in this study the dominant dissolution mechanism changed from matrix dissolution to IEX. These results suggest that ''secondary'' reactions may become dominant under certain environmental conditions and emphasize the need to incorporate these reactions into dissolution rate models

Electrodeionization 2: the migration of nickel ions adsorbed in a flexible ion-exchange resin

NARCIS (Netherlands)

Spoor, P.B.; Veen, ter W.R.; Janssen, L.J.J.

2001-01-01

The removal of nickel ions from a low cross-linked ion-exchange resin using an applied electrical potential gradient was studied. The potential gradient across a bed of ion-exchange particles, in which nickel ions were absorbed, was varied by two methods. One involved a change of cell voltage across

Ion exchange resins as high-dose radiation dosimeters

International Nuclear Information System (INIS)

Alian, A.; Dessouki, A.; El-Assay, N.B.

1984-01-01

This paper reports on the possibility of using various types of ion exchange resins as high-dose radiation dosimeters, by analysis of the decrease in exchange capacity with absorbed dose. The resins studied are Sojuzchim-export-Moscow Cation Exchanger KU-2 and Anion Exchanger AV-17 and Merck Cation Exchanger I, and Merck Anion Exchangers II and III. Over the dose range 1 to 100 kGy, the systems show linearity between log absorbed dose and decrease in resin ion exchange capacity. The slope of this response function differs for the different resins, depending on their ionic form and degree of cross-linking. The radiation sensitivity increases in the order KU-2; Exchanger I; AV-17; Exchanger II; Exchanger III. Merck resins with moisture content of 21% showed considerably higher radiation sensitivity than those with 2 to 3% moisture content. The mechanism of radiation-induced denaturing of the ion exchanger resins involves cleavage and decomposition of functional substituents, with crosslinking playing a stabilizing role, with water and its radiolytic products serving to inhibit radical recombination and interfering with the protection cage effect of crosslinking. (author)

Research of thermal stability of ion exchangers

International Nuclear Information System (INIS)

Stuchlik, S.; Srnkova, J.

1983-01-01

Prior to the fixation of radioactive ion exchangers into bitumen these exchangers have to be dried. The resulting gaseous products may generate explosive mixtures. An analysis was made of the thermal stability of two types of ion exchangers, the cation exchanger KU-2-8 cS and the anion exchanger AV-17-8 cS which are used in the V-1 nuclear power plant at Jaslovske Bohunice. The thermal stability of the anion exchangers was monitored using gas chromatography at temperatures of 100, 120, 140, 160 and 180 degC and by measuring weight loss by kiln-drying at temperatures of 120, 140, 160 and 180 degC. The ion exchanger was heated for 6 hours and samples were taken continuously at one hour intervals. The thermal stability of the cation exchanger was monitored by measuring the weight loss. Gas chromatography showed the release of trimethylamine from the anion exchanger in direct dependence on temperature. The measurement of weight losses, however, only showed higher losses of released products which are explained by the release of other thermally unstable products. The analysis of the thermal stability of the cation exchanger showed the release of SO 2 and the weight loss (following correction for water content) was found only after the fourth hour of decomposition. The experiment showed that the drying of anion exchanger AV-17-8 cS may cause the formation of explosive mixtures. (J.P.)

Nanomaterials-Enhanced Electrically Switched Ion Exchange Process for Water Treatment

International Nuclear Information System (INIS)

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

2009-01-01

The objective of our work is to develop an electrically switched ion exchange (ESIX) system based on conducting polymer/carbon nanotube (CNT) nanocomposites as a new and cost-effective approach for removal of radioactive cesium, chromate, and perchlorate from contaminated groundwater. The ESIX technology combines ion exchange and electrochemistry to provide a selective, reversible method for the removal of target species from wastewater. In this technique, an electroactive ion exchange layer is deposited on a conducting substrate, and ion uptake and elution are controlled directly by modulation of the potential of the layer. ESIX offers the advantages of highly-efficient use of electrical energy combined with no secondary waste generation. Recently, we have improved upon the ESIX process by modifying the conducting substrate with carbon nanotubes prior to the deposition of the electroactive ion exchanger. The nanomaterial-based electroactive ion exchange technology will remove cesium-137, chromate, and perchlorate rapidly from wastewater. The high porosity and high surface area of the electroactive ion exchange nanocomposites results in high loading capacity and minimize interferences for non-target species. Since the ion adsorption/desorption is controlled electrically without generating a secondary waste, this electrically active ion exchange process is a green process technology that will greatly reduce operating costs

KOP ion exchange plant officially opened

International Nuclear Information System (INIS)

Anon.

1982-01-01

The KOP ion exchange plant, which was officially opened in February 1982, can be seen as an important milestone in the history of Klipfontein Organic Products. The plant, erected at a cost of R7 million, has enabled South Africa to achieve virtual self-sufficiency as far as resins are concerned. It will produce R5 million worth of resins per annum, and it has been estimated that it will save the country R3 million per annum in foreign exchange. The plant is the only of its kind in Africa, and will be able to meet 98% of the ion exchange resin requirements of the Republic

Oxidative degradation of ion-exchange resins in acid medium. Vol. 3

International Nuclear Information System (INIS)

Eskander, S.B.; Ghattas, N.K.

1996-01-01

Volume reduction of spent ion-exchange resins used in nuclear facilities receive increasing importance due to the increase in storage cost, unstable physical and chemical properties and their relatively high specific activity (in some cases up to 1 Ci per liter). The present study is part of research program on the treatment and immobilization of radioactive spent ion-exchange resins simulate; hydrogen peroxide was used for the oxidative degradation of spent ion-exchange resins simulate in sulphuric acid medium. Five liters ring digester developed in Karlsruhe nuclear research center-(KFK)- in germany was the chosen option to perform the oxidation process. The work reported focused on the kinetics and mechanism of the oxidation process. Heating the organic resins in sulphuric acid results in its carbonization and partial oxidation of only 1.7% of the carbon added. Results show that the oxidation reaction is a relatively slow process of first order with K value in the order of 10 -4 min -1 , and the main oxidation product was carbon dioxide. The production of carbon oxide in the off gas stream increased sharply by the addition of hydrogen peroxide to the hot sulphuric acid-resin mixture. The results obtained show that more than 97% of the carbon added was oxidized to carbon dioxide and carbon monoxide. The rate constant value (K) of this reaction was calculated to be (1.69±0.13) x 10 -2 min -1 . The results of gas chromatographic analysis indicate that no significant amounts of hazardous organic materials were detected in the off-gas streams. 6 figs., 4 tabs

Kinetics of tritium isotope exchange between liquid pyrrole and gaseous hydrogen

International Nuclear Information System (INIS)

Stolarz, A.

1994-01-01

The kinetics of tritium isotope exchange between liquid pyrrole and gaseous hydrogen has been studied over the temperature range of 290-303 K. The reaction was carried out in the presence of platinum black but in spite of that, it appeared to be relatively slow. The kinetics of the exchange reaction studied could be described by the simple McKay equation. The results obtained suggest that diffusion is the rate-determining step. A mechanism of exchange is proposed. (author) 10 refs.; 2 figs.; 1 tab

Ion exchange equilibrium for some uni-univalent and uni-divalent

African Journals Online (AJOL)

a

KEY WORDS: Duolite A-102 D ion exchange resin, Equilibrium constant, Endothermic ion exchange reaction,. Enthalpy, Thermodynamic study. INTRODUCTION. For proper selection of ion exchange resin in a particular technical application, it is essential to have adequate knowledge regarding their physical and chemical ...

Chloride Ion Adsorption Capacity of Anion Exchange Resin in Cement Mortar

Directory of Open Access Journals (Sweden)

Yunsu Lee

2018-04-01

Full Text Available This paper presents the effect of anion exchange resin (AER on the adsorption of chloride ions in cement mortar. The kinetic and equilibrium behaviors of AER were investigated in distilled water and Ca(OH2 saturated solutions, and then the adsorption of chloride ions by the AER in the mortar specimen was determined. The AER was used as a partial replacement for sand in the mortar specimen. The mortar specimen was coated with epoxy, except for an exposed surface, and then immersed in a NaCl solution for 140 days. The chloride content in the mortar specimen was characterized by energy dispersive X-ray fluorescence analysis and electron probe microanalysis. The results showed that the AER could adsorb the chloride ions from the solution rapidly but had a relatively low performance when the pH of its surrounding environment increased. When the AER was mixed in the cement mortar, its chloride content was higher than that of the cement matrix around it, which confirms the chloride ion adsorption capacity of the AER.

Equilibrium amide hydrogen exchange and protein folding kinetics

International Nuclear Information System (INIS)

Bai Yawen

1999-01-01

The classical Linderstrom-Lang hydrogen exchange (HX) model is extended to describe the relationship between the HX behaviors (EX1 and EX2) and protein folding kinetics for the amide protons that can only exchange by global unfolding in a three-state system including native (N), intermediate (I), and unfolded (U) states. For these slowly exchanging amide protons, it is shown that the existence of an intermediate (I) has no effect on the HX behavior in an off-pathway three-state system (I↔U↔N). On the other hand, in an on-pathway three-state system (U↔I↔N), the existence of a stable folding intermediate has profound effect on the HX behavior. It is shown that fast refolding from the unfolded state to the stable intermediate state alone does not guarantee EX2 behavior. The rate of refolding from the intermediate state to the native state also plays a crucial role in determining whether EX1 or EX2 behavior should occur. This is mainly due to the fact that only amide protons in the native state are observed in the hydrogen exchange experiment. These new concepts suggest that caution needs to be taken if one tries to derive the kinetic events of protein folding from equilibrium hydrogen exchange experiments

Enrichment of 15N by ion exchange chromatography

International Nuclear Information System (INIS)

Ohwaki, Masao; Ohtsuka, Haruhisa; Nomura, Masao; Okamoto, Makoto; Fujii, Yasuhiko

1996-01-01

15 N isotope separation was studied using cation exchange resins which consist of functional groups: sulfonic acid, carboxylic acid and phenol at various concentration of the eluent LiOH. The isotope separation coefficients for these ion exchange resins were observed to be nearly equal, in spite of the large difference in ion exchange characteristics. The effect of flow rate on 15 N isotope separation was also studied, and the results indicate that the operation at high flow rate would be preferable for the industrial process of 15 N enrichment. Based on the preliminary investigations, a continuous operation using a series of ion exchange columns has been carried out in order to achieve high enrichment of 15 N. (author)

Thermodynamics of ion exchange equilibrium for some uni ...

African Journals Online (AJOL)

The study on thermodynamics of ion exchange equilibrium for uni-univalent Cl-/I-, Cl-/Br-, and uni-divalent Cl-/SO42-, Cl-/C2O42- reaction systems was carried out using ion exchange resin Indion FF-IP. The equilibrium constant K was calculated by taking into account the activity coefficient of ions both in solution as well as ...

Inorganic ion exchangers for nuclear waste remediation

Energy Technology Data Exchange (ETDEWEB)

Clearfield, A.; Bortun, A.; Bortun, L.; Behrens, E. [Texas A& M Univ., College Station, TX (United States)

1997-10-01

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

309 plutonium recycle test reactor ion exchanger vault deactivitation report

International Nuclear Information System (INIS)

Griffin, P.W.

1996-03-01

This report documents the deactivation of the ion exchanger vault at the 309 Plutonium Recycle Test Reactor (PRTR) Facility in the 300 Area. The vault deactivation began in May 1995 and was completed in June 1995. The final site restoration and shipment of the low-level waste for disposal was finished in September 1995. The ion exchanger vault deactivation project involved the removal and disposal of twelve ion exchangers and decontaminating and fixing of residual smearable contamination on the ion exchanger vault concrete surfaces

Operation and control of ion-exchange processes for treatment of radioactive wastes

International Nuclear Information System (INIS)

Emelity, L.A.

1967-01-01

A manual dealing with the application of ion-exchange materials to the treatment of radioactive wastes and reviewing the facilities currently using this method. This book is one of three commissioned by the IAEA on the principal methods of concentrating radioactive wastes. The content of this document is: (i) Historical review related to removal of radioactivity; (ii) Principles of ion exchange (iii) Ion-exchange materials; (iv) Limitations of ion exchangers; (v) Application of ion exchange to waste processing; (vi) Operational procedures and experiences; (vii) Cost-of-treatment by ion-exchange. The document also gives a list of producers of ion-exchange material and defines some relevant terms. 101 refs, 31 figs, 27 tabs

Operation and control of ion-exchange processes for treatment of radioactive wastes

Energy Technology Data Exchange (ETDEWEB)

Emelity, L A [Los Alamos National Lab., NM (United States)

1967-12-01

A manual dealing with the application of ion-exchange materials to the treatment of radioactive wastes and reviewing the facilities currently using this method. This book is one of three commissioned by the IAEA on the principal methods of concentrating radioactive wastes. The content of this document is: (i) Historical review related to removal of radioactivity; (ii) Principles of ion exchange (iii) Ion-exchange materials; (iv) Limitations of ion exchangers; (v) Application of ion exchange to waste processing; (vi) Operational procedures and experiences; (vii) Cost-of-treatment by ion-exchange. The document also gives a list of producers of ion-exchange material and defines some relevant terms. 101 refs, 31 figs, 27 tabs.

Incineration of ion-exchange resins

International Nuclear Information System (INIS)

Valkiainen, M.; Nykyri, M.

1985-01-01

Incineration of ion-exchange resins in a fluidized bed was studied on a pilot plant scale at the Technical Research Centre of Finland. Both granular and powdered resins were incinerated in dry and slurry form. Different bed materials were used in order to trap as much cesium and cobalt (inactive tracers) as possible in the bed. Also the sintering of the bed materials was studied in the presence of sodium. When immobilized with cement the volume of ash-concrete is 4 to 22% of the concrete of equal compressive strength acquired by direct solidification. Two examples of multi-purpose equipment capable of incinerating ion-exchange resins are presented. (orig.)

Anisotropic microporous supports impregnated with polymeric ion-exchange materials

Science.gov (United States)

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

1985-05-07

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

Inorganic ion-exchangers for the treatment and disposal of industrial effluents

International Nuclear Information System (INIS)

Hasany, S.M.

2000-01-01

Ion-exchangers can be broadly classified into organic and inorganic ion-exchangers. Inorganic ion-exchangers are stable at high temperatures and radiation dosage, resistant towards oxidizing agents and organic solvents. They are cheap and easy to prepare. Inorganic ion-exchangers, due to their superiority over organic ion-exchangers, have been extensively used for a wide variety of applications including treatment and management of industrial effluents. The criteria governing the division into essential and toxic elements for animal life have been described. The occupational sources of toxic elements and their compounds in the environment have been identified and their tolerance limits prescribed in air, water and food are given. The toxicity and adverse effects of harmful elements and their hazardous compounds are mentioned. Factors influencing sorption of trace elements onto inorganic ion-exchangers are highlighted. Examples of inorganic ion-exchangers are cited where they can be utilized for the treatment of industrial effluents before their safe discharge into waterways and biosphere. (author)

Electrodialytic separation of alkali-element ions with the aid of ion-exchange membranes

International Nuclear Information System (INIS)

Gurskii, V.S.; Moskvin, L.N.

1988-01-01

Electrodialytic separation of ions bearing charges of the same sign with the aid of ion-exchange membranes has been examined in the literature in relation to the so-called ideal membranes, which do not exhibit selectivity with respect to one ion type in ion exchange. It has been shown that separation on such membranes is effective only for counterions differing in size of charge. A matter of greater importance from the practical standpoint is the possibility of using electrodialysis for separating ions bearing like charges and having similar properties, including ionic forms of isotopes of the same element. In this paper they report a comparative study of ion separation, with reference to the Cs-Na pair, by electrodialysis through various types of cation-exchange membranes. Changes of the solution concentration in the cathode compartment were monitored by measurement of 22 Na and 137 Cs activities

Inorganic ion exchange evaluation and design: Silicotitanate ion exchange waste conversion

International Nuclear Information System (INIS)

Balmer, M.L.; Bunker, B.C.

1995-03-01

Ion exchange materials are being evaluated for removing Cs, SR from tank waste. Thermal conversion of a variety of compositions within the Cs 2 O-TiO 2 -SiO 2 phase diagram yielded both glass and crystalline materials, some of which show low leach rates and negligible Cs losses during heat treatment. A new material, CsTiSi 2 0 6 , with a structure isomorphous to pollucite (CsAlSi 2 0 6 ) has been identified. This material represents a new class of crystalline zeolite materials which contain large amounts of titanium. Direct conversion of Cs loaded silicotitanate ion exchangers to CsTiSi 2 O 6 is an excellent alternative to dissolving the Cs-loaded or Cs-eluted exchangers in borosilicate glass because: CsTiSi 2 O 6 is formed using a simple, one step heat treatment. The unique crystalline pollucite-like structure of CsTiSi 2 O 6 traps Cs, and exhibits extremely low Cs leach rates. CsTiSi 2 O 6 is converted to solid waste at a low processing temperature of 700 to 800 C (nominal melter operating temperatures are 1150 C). CsTiSi 2 0 6 concentrates the waste, thus generating lower volumes of expensive HLW. Cs losses due to volatilization during processing of CsTiSi 2 O 6 are extremely low

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

Science.gov (United States)

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

2014-10-21

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

Synthesis of ion-exchange resin for selective thorium and uranyl ions sorption

Science.gov (United States)

Konovalov, Konstantin; Sachkov, Victor

2017-11-01

In this work, the method of ion-exchange resin synthesis selective to radionuclides (uranium and thorium) is presented. The method includes synthesis of polymeric styrene-divinylbenzene macroporous matrix with size of 0.1-0.2 mm, and its subsequent transformation by nitration and then reduction by tin (II) chloride. For passivation of active primary amines partially oxidation by oxygen from air is used. Obtained ion-exchange resin has ratio of sorption sum U+Th to sorption sum of other total rare-earth elements as 1:1.88 at ratio of solid to liquid phase 1:200. The proposed method of ion-exchange resin synthesis is scaled-up for laboratory reactors with volume of 5 and 50 liters.

Hydrogen exchange kinetics changes upon formation of the soybean trypsin inhibitor: trypsin complex

International Nuclear Information System (INIS)

Woodward, C.K.; Ellis, L.M.

1975-01-01

The hydrogen exchange kinetics of the complex of trypsin--soybean trypsin inhibitor (Kunitz) have been compared to the calculated sum of the exchange kinetics for the inhibitor and trypsin measured separately. The exchange rates observed for the complex are substantially less than the sum of the exchange rates in the two individual proteins. These results cannot be accounted for by changes in intermolecular or intramolecular hydrogen bonding. The decrease in exchange rates in the complex are ascribed to changes in solvent accessibility in the component proteins. (U.S.)

Ion exchange fiber by radiation grafting, 1

International Nuclear Information System (INIS)

Fujiwara, Kunio

1990-01-01

Radiation grafting is gaining attention as a method for producing high performance materials. This method can be applied to add functions to existing polymer plastics. The author participated in the research program on the production of ion exchange fiber by radiation grafting and its applicability at the Japan Atomic Energy Research Institute, Takasaki Radiation Chemistry Research Establishment. Consequently, it was clarified that it was possible to introduce the cation exchange group, represented by sulfonic and carboxyl groups, and the anion exchange group, represented by the quarternary ammonium group, to polypropylene fiber available on the market. The ion exchange capacity was able to be controlled by the degree of grafting, i.e. approximately up to 3 meq/g in both strong acid and strong base and approximately up to 5 meq/g in weak acid were obtained. The adsorption performance of ammonia, a representative malodorous substance, was also studied using test cation exchange fiber. The adsorption rate of H type strong acid cation exchange fiber was great, due to the H type having neutral reaction, and the adsorption capacity matched the ion exchange capacity. Although the Cu and Ni types features coordinated adsorption and their adsorption rates were from 1/2 to 1/3 of that of the H type, their adsorption capacities showed increase along with the metal adsorbed. (author)

Separation of seven arsenic species by ion-pair and ion-exchange high performance liquid chromatography

DEFF Research Database (Denmark)

Larsen, Erik Huusfeldt; Hansen, Sven Hedegaard

1992-01-01

Arsenite, arsenate, monomethylarsonate, dimethylarsinate, arsenobetaine, arsenocholine and the tetramethylarsonium ion were subjected to ion-exchange and ion-pair reversed phase HPLC. The ion exchange method was superior in selectivity and time of analysis for the arsenic anions. The ammonium ions...... used for the ion-pair method only resulted in separation of some of the anionic arsenic compounds. Flame atomic absorption spectrometry was used for on-line arsenic-specific detection....

Kinetic Framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System: Modeling Ion Outflow

Science.gov (United States)

Schunk, R. W.; Barakat, A. R.; Eccles, V.; Karimabadi, H.; Omelchenko, Y.; Khazanov, G. V.; Glocer, A.; Kistler, L. M.

2014-12-01

A Kinetic Framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System is being developed in order to provide a rigorous approach to modeling the interaction of hot and cold particle interactions. The framework will include ion and electron kinetic species in the ionosphere, plasmasphere and polar wind, and kinetic ion, super-thermal electron and fluid electron species in the magnetosphere. The framework is ideally suited to modeling ion outflow from the ionosphere and plasmasphere, where a wide range for fluid and kinetic processes are important. These include escaping ion interactions with (1) photoelectrons, (2) cusp/auroral waves, double layers, and field-aligned currents, (3) double layers in the polar cap due to the interaction of cold ionospheric and hot magnetospheric electrons, (4) counter-streaming ions, and (5) electromagnetic wave turbulence. The kinetic ion interactions are particularly strong during geomagnetic storms and substorms. The presentation will provide a brief description of the models involved and discuss the effect that kinetic processes have on the ion outflow.

Incineration of spent ion exchange resin

International Nuclear Information System (INIS)

Hasegawa, Chiaki

1990-01-01

It is a pressing need to reduce radioactive waste which is generated from the maintenance and operation of a nuclear power plant. Incineration of low level combustible solid waste such as polyethylene seats, paper and others have been successfully performed since 1984 at the Shimane Nuclear Power Station. Furthermore, for extending incineration treatment to spent ion exchange resin, the incineration test was carried out in 1989. However, as the cation exchange resin contains sulfur and then incineration generates SOx gases, so the components of this facility will be in a corrosive environment. We surveyed incineration conditions to improve the corrosive environment at the exhaust gas treatment system. This paper includes these test results and improved method to incinerate spent ion exchange resin. (author)

A review of the radiation stability of ion exchange materials

International Nuclear Information System (INIS)

Pillay, K.K.S.

1986-01-01

A comprehensive literature survey on the radiation stability of synthetic organic ion exchangers was published in this journal (Vol. 97, No. 1.). This paper is a brief review of the major findings of this survey along with similar information on synthetic inorganic ion exchangers. The primary goal of this literature survey is to review present knowledge on the effects of ionizing radiations on synthetic ion exchange materials used in radiochemical processing. The information available in the literature shows some general trends in observed qualitative effects by different types of organic and inorganic ion exchange materials. (author)

Isotope effects in ion-exchange equilibria in aqueous and mixed solvent systems

International Nuclear Information System (INIS)

Gupta, A.R.

1979-01-01

Isotope effects in ion-exchange equilibria in aqueous and mixed solvents are analyzed in terms of the general features of ion-exchange equilibria and of isotope effects in chemical equilibria. The special role of solvent fractionation effects in ion-exchange equilibria in mixed solvents is pointed out. The various situations arising in isotope fractionation in ion exchange in mixed solvents due to solvent fractionation effects are theoretically discussed. The experimental data on lithium isotope effects in ion-exchange equilibria in mixed solvents are shown to conform to the above situations. The limitations of ion-exchange equilibria in mixed solvents for isotope fractionation are pointed out. 3 tables

Roles of Bulk and Surface Chemistry in the Oxygen Exchange Kinetics and Related Properties of Mixed Conducting Perovskite Oxide Electrodes

Directory of Open Access Journals (Sweden)

Nicola H. Perry

2016-10-01

Full Text Available Mixed conducting perovskite oxides and related structures serving as electrodes for electrochemical oxygen incorporation and evolution in solid oxide fuel and electrolysis cells, respectively, play a significant role in determining the cell efficiency and lifetime. Desired improvements in catalytic activity for rapid surface oxygen exchange, fast bulk transport (electronic and ionic, and thermo-chemo-mechanical stability of oxygen electrodes will require increased understanding of the impact of both bulk and surface chemistry on these properties. This review highlights selected work at the International Institute for Carbon-Neutral Energy Research (I2CNER, Kyushu University, set in the context of work in the broader community, aiming to characterize and understand relationships between bulk and surface composition and oxygen electrode performance. Insights into aspects of bulk point defect chemistry, electronic structure, crystal structure, and cation choice that impact carrier concentrations and mobilities, surface exchange kinetics, and chemical expansion coefficients are emerging. At the same time, an understanding of the relationship between bulk and surface chemistry is being developed that may assist design of electrodes with more robust surface chemistries, e.g., impurity tolerance or limited surface segregation. Ion scattering techniques (e.g., secondary ion mass spectrometry, SIMS, or low energy ion scattering spectroscopy, LEIS with high surface sensitivity and increasing lateral resolution are proving useful for measuring surface exchange kinetics, diffusivity, and corresponding outer monolayer chemistry of electrodes exposed to typical operating conditions. Beyond consideration of chemical composition, the use of strain and/or a high density of active interfaces also show promise for enhancing performance.

Simulation of ITG instabilities with fully kinetic ions and drift-kinetic electrons in tokamaks

Science.gov (United States)

Hu, Youjun; Chen, Yang; Parker, Scott

2017-10-01

A turbulence simulation model with fully kinetic ions and drift-kinetic electrons is being developed in the toroidal electromagnetic turbulence code GEM. This is motivated by the observation that gyrokinetic ions are not well justified in simulating turbulence in tokamak edges with steep density profile, where ρi / L is not small enough to be used a small parameter needed by the gyrokinetic ordering (here ρi is the gyro-radius of ions and L is the scale length of density profile). In this case, the fully kinetic ion model may be useful. Our model uses an implicit scheme to suppress high-frequency compressional Alfven waves and waves associated with the gyro-motion of ions. The ion orbits are advanced by using the well-known Boris scheme, which reproduces correct drift-motion even with large time-step comparable to the ion gyro-period. The field equation in this model is Ampere's law with the magnetic field eliminated by using an implicit scheme of Faraday's law. The current contributed by ions are computed by using an implicit δf method. A flux tube approximation is adopted, which makes the field equation much easier to solve. Numerical results of electromagnetic ITG obtained from this model will be presented and compared with the gyrokinetic results. This work is supported by U.S. Department of Energy, Office of Fusion Energy Sciences under Award No. DE-SC0008801.

Characterization of poly(allylamine) as a polymeric ligand for ion-exchange protein chromatography.

Science.gov (United States)

Li, Ming; Li, Yanying; Yu, Linling; Sun, Yan

2017-02-24

This work reports poly(allylamine) (PAA), as a polymeric ion-exchange ligand for protein chromatography. Sepharose FF was modified with PAA, and six anion exchangers with ionic capacities (ICs) from 165 to 618mmol/L were prepared. Inverse size exclusion chromatography, adsorption equilibrium, uptake kinetics and column elution were performed. It was found that both the adsorption capacity and effective diffusivity maintained low values in the IC range of 165-373mmol/L, but they started to increase beyond 373mmol/L, and increased by 80% and 23 times, respectively, when the IC reached 618mmol/L. Interestingly, a drastic decrease of pore size was observed around the IC of 373mmol/L. The results suggest that the PAA chains played an important role in protein adsorption by altering the inner pore structure of the gels. It is considered that, PAA chains turn from inextensible states with multipoint-grafting on the pore surface at low coupling densities (IC373mmol/L). These characters of the grafted chains at higher IC values benefit in protein adsorption by three-dimensional binding and encouraged the happening of "chain delivery" of bound proteins on the chains. Besides, the ion exchangers showed favorable adsorption and uptake properties in a wide ionic strength range, 0-500mmol/L NaCl, indicating much better salt tolerance feature than the so-far reported ion exchangers. Moreover, a mild condition of pH 5.0 offered effective recovery of bound proteins in elution chromatography. The results indicate that the PAA-based anion exchanger of a high IC value is promising for high-capacity protein chromatography dealing with feedstock of a wide range of ionic strengths. Copyright © 2016 Elsevier B.V. All rights reserved.

Composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix. Methods of modification of properties of inorganic ion-exchangers for application in column packed beds

International Nuclear Information System (INIS)

Sebesta, F.

1997-01-01

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 ion-exchangers and polyacrylonitrile binding matrix is described, advantages and disadvantages of such sorbents are discussed. Proposed fields of application include tratment of liquid radioactive and/or hazardous wastes, decontamination of natural water as well as analytical applications. (author)

Radiocarbon detection by ion charge exchange mass spectrometry

International Nuclear Information System (INIS)

Hotchkis, Michael; Wei, Tao

2007-01-01

A method for detection of radiocarbon at low levels is described and the results of tests are presented. We refer to this method as ion charge exchange mass spectrometry (ICE-MS). The ICE-MS instrument is a two stage mass spectrometer. In the first stage, molecular interferences which would otherwise affect radiocarbon detection at mass 14 are eliminated by producing high charge state ions directly in the ion source (charge state ≥2). 14 N interference is eliminated in the second stage by converting the beam to negative ions in a charge exchange cell. The beam is mass-analysed at each stage. We have built a test apparatus consisting of an electron cyclotron resonance ion source and a pair of analysing magnets with a charge exchange cell in between, followed by an electrostatic analyser to improve the signal to background ratio. With this apparatus we have measured charge exchange probabilities for (C n+ → C - ) from 4.5 to 40.5 keV (n = 1-3). We have studied the sources of background including assessment of limits for nitrogen interference by searching for negative ions from charge exchange of 14 N ions. Our system has been used to detect 14 C in enriched samples of CO 2 gas with 14 C/ 12 C isotopic ratio down to the 10 -9 level. Combined with a measured sample consumption rate of 4 ng/s, this corresponds to a capability to detect transient signals containing only a few μBq of 14 C activity, such as may be obtained from chromatographic separation. The method will require further development to match the sensitivity of AMS with a gas ion source; however, even in its present state its sensitivity is well suited to tracer studies in biomedical research and drug development

Kinetics from Replica Exchange Molecular Dynamics Simulations.

Science.gov (United States)

Stelzl, Lukas S; Hummer, Gerhard

2017-08-08

Transitions between metastable states govern many fundamental processes in physics, chemistry and biology, from nucleation events in phase transitions to the folding of proteins. The free energy surfaces underlying these processes can be obtained from simulations using enhanced sampling methods. However, their altered dynamics makes kinetic and mechanistic information difficult or impossible to extract. Here, we show that, with replica exchange molecular dynamics (REMD), one can not only sample equilibrium properties but also extract kinetic information. For systems that strictly obey first-order kinetics, the procedure to extract rates is rigorous. For actual molecular systems whose long-time dynamics are captured by kinetic rate models, accurate rate coefficients can be determined from the statistics of the transitions between the metastable states at each replica temperature. We demonstrate the practical applicability of the procedure by constructing master equation (Markov state) models of peptide and RNA folding from REMD simulations.

Ion exchange currents in vacuum accelerator tubes

International Nuclear Information System (INIS)

Eastham, D.A.; Thorn, R.

1978-01-01

Ion exchange currents (microdischarges) have been observed in short lengths of accelerator tube. The occurrence of these discharges can be related to the trajectories of ions in the tube. High-resolution mass spectra of the negative and positive ion components have been obtained. (author)

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

KAUST Repository

Geise, Geoffrey M.

2014-08-26

© the Partner Organisations 2014. Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions. Our goal in this work was to better understand membrane behaviour in aqueous ammonium bicarbonate, which is of interest for closed-loop energy generation processes. Here we characterized the permselectivity of four commercial ion exchange membranes in aqueous solutions of sodium chloride, ammonium chloride, sodium bicarbonate, and ammonium bicarbonate. This stepwise approach, using four different ions in aqueous solution, was used to better understand how these specific ions affect ion transport in ion exchange membranes. Characterization of cation and anion exchange membrane permselectivity, using these ions, is discussed from the perspective of the difference in the physical chemistry of the hydrated ions, along with an accompanying re-derivation and examination of the basic equations that describe membrane potential. In general, permselectivity was highest in sodium chloride and lowest in ammonium bicarbonate solutions, and the nature of both the counter- and co-ions appeared to influence measured permselectivity. The counter-ion type influences the binding affinity between counter-ions and polymer fixed charge groups, and higher binding affinity between fixed charge sites and counter-ions within the membrane decreases the effective membrane charge density. As a result permselectivity decreases. The

An Empirical Formula From Ion Exchange Chromatography and Colorimetry.

Science.gov (United States)

Johnson, Steven D.

1996-01-01

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

The Role of Ion Exchange Membranes in Membrane Capacitive Deionisation.

Science.gov (United States)

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

2017-09-14

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

A study on dry decontamination using ion exchange polymer

International Nuclear Information System (INIS)

Jung, Ki Jung; Ahn, Byung Gil

1997-12-01

Through the project of A study on dry decontamination using ion exchange polymer , the followings were investigated. 1. Highly probable decontamination technologies for the decontamination were investigated. 2. Development of gel type decontamination agent using ion-exchange resin powder (mixed type) as an ion exchanger. 3. Manufacturing of contaminated specimens (5 kinds) with Cs-137 solution and dust / Cs-137 solution. 4. Decontamination performance evaluation of the manufactured agent. 5. Analysis of composition (XRF) and the structure of surface of specimens (optic micrography). (author). 20 refs., 11 figs

Effects of apolipoproteins on the kinetics of cholesterol exchange

International Nuclear Information System (INIS)

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

1991-01-01

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

Effects of ionizing radiation on modern ion exchange materials

International Nuclear Information System (INIS)

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

1993-10-01

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

Minor Actinide Separations Using Ion Exchangers Or Ionic Liquids

International Nuclear Information System (INIS)

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

2011-01-01

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.

The kinetics and thermodynamics of adsorption of heavy metal ions ...

African Journals Online (AJOL)

Titanium-Pillared and Un-Pillared bentonite clays were studied in order to evaluate the thermodynamics and kinetics of heavy metal ion removal from aqueous solutions. The results showed that the maximum sorption of Cu, Cd, Hg and Pb ions occurred within 30 minutes. A pseudo-second order kinetic model was used to ...

Effects of the spaces available for cations in strongly acidic cation-exchange resins on the exchange equilibria by quaternary ammonium ions and on the hydration states of metal ions.

Science.gov (United States)

Watanabe, Yuuya; Ohnaka, Kenji; Fujita, Saki; Kishi, Midori; Yuchi, Akio

2011-10-01

The spaces (voids) available for cations in the five exchange resins with varying exchange capacities and cross-linking degrees were estimated, on the basis of the additivity of molar volumes of the constituents. Tetraalkylammonium ions (NR(4)(+); R: Me, Et, Pr) may completely exchange potassium ion on the resin having a larger void radius. In contrast, the ratio of saturated adsorption capacity to exchange capacity of the resin having a smaller void radius decreased with an increase in size of NR(4)(+) ions, due to the interionic contacts. Alkali metal ions could be exchanged quantitatively. While the hydration numbers of K(+), Rb(+), and Cs(+) were independent of the void radius, those of Li(+) and Na(+), especially Na(+), decreased with a decrease in void radius. Interionic contacts between the hydrated ions enhance the dehydration. Multivalent metal ions have the hydration numbers, comparable to or rather greater than those in water. A greater void volume available due to exchange stoichiometry released the interionic contacts and occasionally promoted the involvement of water molecules other than directly bound molecules. The close proximity between ions in the conventional ion-exchange resins having higher exchange capacities may induce varying interactions.

Exchange scattering of quasiparticles by positive ion in He3

International Nuclear Information System (INIS)

Ehdel'shtejn, V.M.

1983-01-01

The difference in the mobility of negative and positive ions in normal 3 He at low temperatures is discussed. The mobility mechanisms for the ions of different sign are qualitatively different since the positive ion can exchange quasiparticles with the helium atoms from the ice-like shell surrounding the ion. A study of the mobility in a magnetic field may yield quantitative information on the magnitude of the exchange interaction. A calculation for the exchange scattering model is carried out and it is shown that a logarithmic contribution to the positive ion mobility μsub(+)(T) appears which is analogous to the Kondo effect

Study on Modification of NaX Zeolites: The Cobalt (II-Exchange Kinetics and Surface Property Changes under Thermal Treatment

Directory of Open Access Journals (Sweden)

Hoai-Lam Tran

2016-01-01

Full Text Available The cobalt (II ion-exchange process followed the Freundlich and Langmuir adsorption models as well as the pseudo-second-order kinetic model. The cobalt-exchanged contents increased when the initial Co(NO32 solution concentration increased up to 0.14 mol L−1 at the optimal pH of 6.05. The N2 adsorption isotherms are mixed types I/II isotherms and H3 type hysteresis. Both the micropore and mesopore adsorptions occurred during the adsorption process. The modification, which is both the cobalt (II exchange and thermal treatment, significantly improved the surface properties of NaX zeolites. Accordingly, the optimal temperature range is 500 to 600°C for a thermal treatment. This is consistent with the results of XRD analysis.

Synthesis and characterization of inorganic ion exchangers based on mixed oxide tin-titanium to be used in recovery of cadmium and nickel and photoluminescent studies

International Nuclear Information System (INIS)

Paganini, Paula Pinheiro

2007-01-01

This work presents the synthesis, characterization and adsorption studies of inorganic ion exchangers based on mixed tin-titanium oxide for recovery of cadmium and nickel metals from aqueous effluents, discarded in the environment mainly through Ni-Cd battery. The exchangers were synthesized by sol-gel modified method using a mixture of tin(IV) chloride and titanium(III) chloride and ammonium hydroxide, as precursors reagents. The materials obtained: SnO 2 /TiO 2 and SnO 2 /TiO 2 :Eu 3+ were characterized by infrared spectroscopy, thermal analysis, scattering electronic microscopy (SEM), X-ray powder diffraction (XRD) (powder method) and electronic spectroscopy (excitation and emission) for the europium doped exchanger. The same materials also were synthesized in polymeric matrix too and can be used in column, because the synthesized materials showed crystals size in nano metric scale. It was determined by the distribution ratios for metals taking as parameters the influence of pH, the concentration of metals (by adsorption isotherms) and the contact time (by adsorption kinetic). The inorganic ion exchanger presented high exchange capacity with adsorption percent above 90 por cent for the studied conditions, quickly kinetic, heterogeneous exchange surfaces, physic adsorption and spontaneous process of exchange. To the doped exchanger spectroscopy properties were studied and also it was calculated the intensity parameters and it was found a satisfactory quantum yield. (author)

Using contemporary liquid chromatography theory and technology to improve capillary gradient ion-exchange separations.

Science.gov (United States)

Wouters, Bert; Broeckhoven, Ken; Wouters, Sam; Bruggink, Cees; Agroskin, Yury; Pohl, Christopher A; Eeltink, Sebastiaan

2014-11-28

The gradient-performance limits of capillary ion chromatography have been assessed at maximum system pressure (34.5 MPa) using capillary columns packed with 4.1 μm macroporous anion-exchange particles coated with 65 nm positively-charged nanobeads. In analogy to the van-Deemter curve, the gradient performance was assessed applying different flow rates, while decreasing the gradient time inversely proportional to the increase in flow rate in order to maintain the same retention properties. The gradient kinetic-performance limits were determined at maximum system pressure, applying tG/t0=5, 10, and 20. In addition, the effect of retention on peak width was assessed in gradient mode for mono-, di-, and trivalent inorganic anions. The peak width of late-eluting ions can be significantly reduced by using concave gradient, resulting in better detection sensitivity. A signal enhancement factor of 8 was measured for a late-eluting ion when applying a concave instead of a linear gradient. For the analysis of a complex anion mixture, a coupled column with a total length of 1.05 m was operated at the kinetic-performance limit applying a linear 250 min gradient (tG/t0=10). The peak capacity varied between 200 and 380 depending on analyte retention, and hence on charge and size of the ion. Copyright © 2014 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

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

2006-02-28

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

Nickel speciation and complexation kinetics in freshwater by ligand exchange and DPCSV

NARCIS (Netherlands)

Han Bin Xue,; Jansen, S.; Prasch, A.; Sigg, L.

2001-01-01

A technique of ligand exchange with DMG (dimethylglyoxime) and DPCSV was applied to determine Ni speciation in lake, river, and groundwater samples. The working conditions related to ligand-exchange equilibrium were optimized, and the ligand-exchange kinetics were examined. The observed

Isotope exchange of strontium and molybdate ions in strontium polymolybdates

International Nuclear Information System (INIS)

Atun, G.

2002-01-01

The heterogeneous isotopic exchange reactions in strontium polymolybdates of Sr 2+ and MoO 4 2- ions in the strontium nitrate and sodium molybdate solutions have been studied using 90 Sr and 99 Mo as tracers. Electrometric methods have been used to study the compositions of strontium molybdates obtained by adding strontium chloride to a progressively acidified solution of sodium molybdate. It has been found that the exchange fraction increases with increasing chain length of strontium polymolybdate. The exchange equilibrium constant (K ex ) has been calculated between 298 and 348 K as well as ΔG deg, ΔH deg and ΔS deg. The results indicate that Sr 2+ cations have a much higher affinity for exchangers than MoO 4 2- anions. By fitting the data to the Dubinin-Radushkevich (D-R) isotherm it has been shown that the exchange capacity (X m ) for both ions is affected by the ion adsorption process at low temperatures and by the ion exchange process at high temperatures. At high concentrations, the recrystallization process contributes to on the cation exchange but is ineffective on the anion exchange mechanism. (author)

The application of synthetic inorganic ion exchangers to analytical chemistry, 2

International Nuclear Information System (INIS)

Abe, Mitsuo

1974-01-01

Regarding acidic salts, description is made on the general behaviour of the acidic salts of tetravalent metals and each of zirconium salts, titanium salts, stannic salts, cerium salts, thorium salts, chromium salts, and others. On heteropolyacid salts, ammonium 12-molybdophosphated and phosphorus wolframate are described. On insoluble ferrocyanides, the behaviour of various complex salts is explained. In the discussion on the general behaviour of the acidic salts of tetravalent metals, the ideality of ion exchange, the stability and solubility of the acidic salts, thermal stability and radiation resistance, the ion sieving effect of various acidic salts, and the selectivity of the acidic salts are stated. Zirconium gives a number of acidic salts, such as zirconium phosphate, crystalline zirconium phosphate, zirconium phrophosphate, various polyphosphates of zirconium, zirconium phosphate-silicate, zirconium arsenate, zirconium antimonate, zirconium molybdate, zirconium tungstate, etc. Useful titanium salts for ion exchange are titanium phosphate, titanium aresenate, titanium antimonate, titanium tungstate, titanium molybdate, titanium vanadate, and titanium selenate. The distribution coefficients of metal ions, inorganic-separation of various inorganic ion exchangers, the exchange characteristics of various elements on various ion exchangers, and the selectivity of various inorganic ion-exchangers are tabulated. (Fukutomi, T.)

Application of ion exchangers

International Nuclear Information System (INIS)

Markhol, M.

1985-01-01

Existing methods of multi-element separation for radiochemical analysis are considered. The majority of existing methods is noted to be based on application of organic and inorganic ion exchangers. Distillation, coprecipitation, extraction as well as combination of the above methods are also used. Concrete flowsheets of multi-element separation are presented

Labile/inert metal species in aquatic humic substances: an ion-exchange study

International Nuclear Information System (INIS)

Burba, P.

1994-01-01

An ion-exchange procedure has been developed for the analytical fractionation of metals (e.g. Al, Co, Cu, Fe, Mn, Ni, Pb, Zn) forming labile/inert complexes with aquatic humic substances (HS) isolated (XAD 2, XAD 8, ultrafiltration) from bog, forest, ground and lake water. Using 1-(2-hydroxyphenylazo)-2-naphthol groups immobilized on cellulose (Cellulose HYPHAN TM ) as chelating collector (batch and column procedure, resp.) for reactive metal fractions in dissolved HS, the kinetics and the degree of separation (referred to the total metal content) serve for the operational characterization of the metal lability. According to the separation kinetics (96 h), mostly the reactivity order Mn > Zn > Co > Pb > Ni > Cu >> Al > Fe is observed for the above metals in HS, resulting in recoveries of > 98% for Mn and Zn, but strongly varying for the other metals (e.g., 44-95% Cu, 18-84% Fe). (orig.)

Advanced ion exchange resins for PWR condensate polishing

International Nuclear Information System (INIS)

Hoffman, B.; Tsuzuki, S.

2002-01-01

The severe chemical and mechanical requirements of a pressurized water reactor (PWR) condensate polishing plant (CPP) present a major challenge to the design of ion exchange resins. This paper describes the development and initial operating experience of improved cation and anion exchange resins that were specifically designed to meet PWR CPP needs. Although this paper focuses specifically on the ion exchange resins and their role in plant performance, it is also recognized and acknowledged that excellent mechanical design and operation of the CPP system are equally essential to obtaining good results. (authors)

Evaluation of ferrocyanide anion exchange resins regarding the uptake of Cs+ ions and their regeneration

International Nuclear Information System (INIS)

Won, Hui Jun; Mooon, Jei Kwon; Jung, Chong Hun; Chung, Won Yang

2008-01-01

Ferrocyanide-anion exchange resin was prepared and the prepared ion exchange resins were tested on the ability to uptake Cs + ion. The prepared ion exchange resins were resin-KCoFC, resin-KNiFC, and resin-KCuFC. The three tested ion exchange resins showed ion exchange selectivity on the Cs + ion of the surrogate soil decontamination solution, and resin- KCoFC showed the best Cs + ion uptake capability among the tested ion exchange resins. The ion exchange behaviors were explained well by the modified Dubinin-Polanyi equation. A regeneration feasibility study of the spent ion exchange resins was also performed by the successive application of hydrogen peroxide and hydrazine. The desorption of the Cs + ion from the ion exchange resin satisfied the electroneutrality condition in the oxidation step; the desorption of the Fe 2+ ion in the reduction step could also be reduced by adding the K + ion

Electrodialytic decontamination of spent ion exchange resins

International Nuclear Information System (INIS)

Nott, B.R.

1982-01-01

Development of a novel electrodialytic decontamination process for the selective removal of radioactive Cs from spent ion exchange resins containing large amounts of Li is described. The process involves passage of a dc electric current through a bed of the spent ion exchange resin in a specially designed electrodialytic cell. The radiocesium so removed from a volume of the spent resin is concentrated onto a much smaller volume of a Cs selective sorbent to achieve a significant radioactive waste volume reduction. Technical feasibility of the electrodialytic resin decontamination process has been demonstrated on a bench scale with a batch of simulated spent ion exchange resin and using potassium cobalt ferrocyanide as the Cs selective sorbent. A volume reduction factor between 10 and 17 has been estimated. The process appears to be economically attractive. Improvements in process economics can be expected from optimization of the process. Other possible applications of the EDRD process have been identified

Modeling of Crystalline Silicotitanate Ion Exchange Columns

International Nuclear Information System (INIS)

Walker, D.D.

1999-01-01

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

Lead titanate nanotubes synthesized via ion-exchange method: Characteristics and formation mechanism

International Nuclear Information System (INIS)

Song Liang; Cao Lixin; Li Jingyu; Liu Wei; Zhang Fen; Zhu Lin; Su Ge

2011-01-01

Highlights: → Lead titanate nanotubes PbTi 3 O 7 were firstly synthesized by ion-exchange method. → Sodium titanate nanotubes have ion exchangeability. → Lead titanate nanotubes show a distinct red shift on absorption edge. - Abstract: A two-step method is presented for the synthesis of one dimensional lead titanate (PbTi 3 O 7 ) nanotubes. Firstly, titanate nanotubes were prepared by an alkaline hydrothermal process with TiO 2 nanopowder as precursor, and then lead titanate nanotubes were formed through an ion-exchange reaction. We found that sodium titanate nanotubes have ion exchangeability with lead ions, while protonated titanate nanotubes have not. For the first time, we distinguished the difference between sodium titanate nanotubes and protonated titanate nanotubes in the ion-exchange process, which reveals a layer space effect of nanotubes in the ion-exchange reaction. In comparison with sodium titanate, the synthesized lead titanate nanotubes show a narrowed bandgap.

Thermodynamic characteristics of sorption of metal-ions by ion exchangers

OpenAIRE

ABBASOV ALIADDIN DAYYAN; JAFARLI MAHNUR MOYSUN; MEMMEDOVA FIZZA SADIKH; HEYDEROVA FARAH FARMAN

2016-01-01

Conditions of sorption equilibrium of copper, zinc, cadmium and lead-ions by chelatforming resins Diaion CR 11, Dowex M 4195 and Duolite C 467 depending on the degree of neutralization of their ionogenic groups, the acidity of the medium and concentration of solutions are studied; corresponding equations expressing the isotherms of sorption are offered. Kinetics of these processes is studied; on the basis of equilibrium and kinetic parameters are calculated thermodynamic quantities. It is sho...

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

Science.gov (United States)

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

2009-06-01

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

Inorganic ion exchangers. Application to liquid effluent processing

International Nuclear Information System (INIS)

Dozol, M.

1983-10-01

Main inorganic ion exchangers used for radioactive liquid effluents presented in this report are: synthetic and natural zeolites, in titanium oxides, titanates, niobates, tantalates, zirconates, some insoluble salts of zirconium, molybdenum and tin, heteropolyacids and polyantimonic acid. Properties of these ion exchangers are described: structure, adsoption, radiation effects and thermal stability, application to waste processing, radioactive waste storage uranium and cesium 137 recovery are evoked [fr

Ion Exchange Modeling Of Cesium Removal From Hanford Waste Using Spherical Resorcinol-Formaldehyde Resin

Energy Technology Data Exchange (ETDEWEB)

Aleman, S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hamm, L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Smith, F. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2007-06-27

This report discusses the expected performance of spherical Resorcinol-Formaldehyde (RF) ion exchange resin for the removal of cesium from alkaline Hanford radioactive waste. Predictions of full scale column performance in a carousel mode are made for the Hot Commissioning, Envelope B, and Subsequent Operations waste compositions under nominal operating conditions and for perturbations from the nominal. Only the loading phase of the process cycle is addressed in this report. Pertinent bench-scale column tests, kinetic experiments, and batch equilibrium experiments are used to estimate model parameters and to benchmark the ion-exchange model. The methodology and application presented in this report reflect the expected behavior of spherical RF resin manufactured at the intermediate-scale (i.e., approximately 100 gallon batch size; batch 5E-370/641). It is generally believed that scale-up to production-scale in resin manufacturing will result in similarly behaving resin batches whose chemical selectivity is unaffected while total capacity per gram of resin may vary some. As such, the full-scale facility predictions provided within this report should provide reasonable estimates of production-scale column performance.

New sorbents and ion exchangers for nuclear waste solution remediation

International Nuclear Information System (INIS)

Clearfield, A.; Peng, G.Z.; Cahill, R.A.; Bellinghausen, P.; Aly, H.I.; Scott, K.; Wang, J.D.

1993-01-01

There is now a concerted effort underway to clean up the accumulated nuclear wastes as the major sites around the country. Because of the complexity of the mixtures in the holding tanks highly specific exchangers are required to fulfill a multitude of desired tasks. These include removal of Cs + , Sr 2+ , Tc, Actinides and possible recovery of rare and precious metals. No one exchanger or sequestrant can accomplish these tasks and a variety of exchangers in a multistep process will be required. The behavior of a number of inorganic ion exchangers in a multistep process will be required. The behavior of a number of inorganic ion exchangers and new organo-inorganic exchangers towards Cs + , Sr 2+ and rare-earth ions in acid and basic media will be described. Preliminary data on the effect of high levels of sodium nitrate on the uptake of these ions will also be presented, as well as the changes observed in selectivity in simulated waste solutions. A possible separation scheme based on these data will be described

Thermal Analysis for Ion-Exchange Column System

Energy Technology Data Exchange (ETDEWEB)

Lee, Si Y.; King, William D.

2012-12-20

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

Waste separation and pretreatment using crystalline silicotitanate ion exchangers

Energy Technology Data Exchange (ETDEWEB)

Tadros, M.E.; Miller, J.E. [Sandia National Lab., Albuquerque, NM (United States); Anthony, R.G. [Texas A& M Univ., College Station, TX (United States)

1997-10-01

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

Ion exchange removal of technetium from salt solutions

International Nuclear Information System (INIS)

Walker, D.D.

1983-01-01

Ion exchange methods for removing technetium from waste salt solutions have been investigated by the Savannah River Laboratory (SRL). These experiments have shown: Commercially available anion exchange resins show high selectivity and capacity for technetium. In column runs, 150 column volumes of salt solution were passed through an ion exchange column before 50% 99 Tc breakthrough was reached. The technetium can be eluted from the resin with nitric acid. Reducing resins (containing borohydride) work well in simple hydroxide solutions, but not in simulated salt solutions. A mercarbide resin showed a very high selectivity for Tc, but did not work well in column operation

Triple-membrane reduces need for ion exchange regeneration

International Nuclear Information System (INIS)

Valcour, H.

1989-01-01

Triple-membrane water treatment systems are comprised of ultrafiltration units for pretreatment, electrodialysis reversal primary demineralizers, reverse osmosis secondary demineralizers, portable ion exchange unit polishing demineralizers, and ultraviolet sterilizers. The triple-membrane process is designed to provide an unprecedented degree of pretreatment to maximize efficiency, durability and reliability of the reverse osmosis, whilst reducing the required regeneration frequency of the ion exchange demineralizer by one to two orders of magnitude. (author)

Isotope exchange kinetic of phosphorus in soils from Pernambuco State -Brazil

International Nuclear Information System (INIS)

Figueiredo, F.J.B. de.

1989-12-01

The applicability of isotopic exchange kinetics of 32 p to characterize phosphorus available to plants and to diagnose the reactivity of soil-fertilizer-P in six soils from Pernambuco is described. This methodology was compared with anion exchange resin, isotopic exchange equilibrium methods (E-value and L-value) and P absorption by plants. The first greenhouse experiment had the following treatments: 1) with P and, 2) with addition of 43.7 mg P/Kg of soil, incubated for O, 42 and 84 days before seeding. The kinetic of isotopic exchange (KIE), resin-P and E-value were determined before seeding and after harvesting pearl millet grown for 42 days. Results indicated that the KIE parameters rated the soils more efficiently, in terms of available P and soil-fertilizer-P reactivity, than resin-P, E-value and L-value. (author). 38 refs, 2 figs, 18 tabs

The ion exchange and its connection the industry II.- Calculation methods for installations; El cambio de ion y su relacion con la industria II.- Metodos de calculo de instalaciones

Energy Technology Data Exchange (ETDEWEB)

Uriarte Hueda, A; Lopez Perez, B; Gutierrez Jodra, L

1960-07-01

An exposure is made of calculation methods for ion exchange installations based on kinetic considerations and similarity with other unitary operations. Factors to be experimentally obtained as well as difficulties which may occur in its determination are also given. Calculation procedures most commonly used in industry are enclosed and explained with numerical resolution of a problem of water demineralization. (Author) 22 refs.

Commercial Ion Exchange Resin Vitrification Studies

International Nuclear Information System (INIS)

Cicero-Herman, C.A

2002-01-01

In the nuclear industry, ion exchange resins are used for purification of aqueous streams. The major contaminants of the resins are usually the radioactive materials that are removed from the aqueous streams. The use of the ion exchange resins creates a waste stream that can be very high in both organic and radioactive constituents. Therefore, disposal of the spent resin often becomes an economic problem because of the large volumes of resin produced and the relatively few technologies that are capable of economically stabilizing this waste. Vitrification of this waste stream presents a reasonable disposal alternative because of its inherent destruction capabilities, the volume reductions obtainable, and the durable product that it produces

Ion exchange properties of carboxylate bagasse

International Nuclear Information System (INIS)

Nada, A.M.A.; Hassan, M.L.

2005-01-01

Bagasse fibers were chemically modified using three different reactions: esterification using monochloro acetic acid, esterification using succinic anhydride, and oxidation using sodium periodate and sodium chlorite to prepare cation exchanger bearing carboxylic groups. Bagasse was crosslinked using epichlorohydrin before chemical modification to avoid loss of its constituents during the chemical modification. The structure of the prepared derivatives was proved using Fourier transform infrared (FTIR) and chemical methods. The ability of the prepared bagasse cation exchangers to adsorb heavy metal ions (Cu +2 , Ni +2 , Cr +3 , Fe +3 ), on a separate basis or in a mixture of them, at different metal ion concentration was tested. Thermal stability of the different bagasse derivative was studied using thermogravimetric analysis (TGA)

Treatment of low level radioactive liquid wastes using composite ion-exchange resins based on polyurethane foam

International Nuclear Information System (INIS)

Rao, S.V.S.; Lekshmi, R.; Mani, A.G.S.; Sinha, P.K.

2010-01-01

Composite ion-exchange resins were prepared by coating copper-ferrocyanide (CFC) and hydrous manganese oxide (HMO) powders on polyurethane (PU) foam. Polyvinyl acetate/Acetone was used as a binder. The foam was loaded with about five times its weight with CFC and HMO powders. The distribution coefficients of CFC-PU foam and HMO-PU foam for cesium and strontium respectively were estimated. Under similar conditions the HMO-PU foam showed higher capacity as well as better kinetics for removal of strontium than CFC-PU foam for Cs. The pilot plant scale studies were conducted using a mixed composite ion-exchange resin bed. About 1000 bed volumes could be passed before attaining a DF of 10 from an initial value of 60-80. The spent resin was digested in alkaline KMnO 4 and the digested liquid was fixed in cement matrix. The matrices were characterized with respect to compressive strength and leach resistance. (author)

Improvements in and relating to ion-exchange

International Nuclear Information System (INIS)

Heal, H.G.

1975-01-01

It has been found that the relatively expensive ion exchange materials normally used can be extensively replaced by relatively inexpensive material comprised of long-weathered basalt. This has been found to effect rapid and efficient ion exchange with a capacity comparable with, and in some cases greater than, the usual artificial materials. The basalt should contain at least 50% by weight of particles of size below 3cm mesh. Olivine basalt has proved particularly effective. Examples given include removal of Cu and Co, application to water softening, and to the removal of 137 Cs from milk. Other applications mentioned include removal of Ca, 90 Sr, Pb, Zn, Hg, Ni, and Cr, extraction of metal ions from seawater, purification of industrial effluents, etc. (U.K.)

Development of Electrically Switched Ion Exchange Process for Selective Ion Separations

International Nuclear Information System (INIS)

Rassat, Scot D.; Sukamto, Johanes H.; Orth, Rick J.; Lilga, Michael A.; Hallen, Richard T.

1999-01-01

The electrically switched ion exchange (ESIX) process, being developed at Pacific Northwest National Laboratory, provides an alternative separation method to selectively remove ions from process and waste streams. In the ESIX process, in which an electroactive ion exchange film is deposited onto a high surface area electrode, uptake and elution are controlled directly by modulating the electrochemical potential of the film. This paper addresses engineering issues necessary to fully develop ESIX for specific industrial alkali cation separation challenges. The cycling and chemical stability and alkali cation selectivity of nickel hexacyanoferrate (NiHCF) electroactive films were investigated. The selectivity of NiHCF was determined using cyclic voltammetry and a quartz crystal microbalance to quantify ion uptake in the film. Separation factors indicated a high selectivity for cesium and a moderate selectivity for potassium in high sodium content solutions. A NiHCF film with improved redox cycling and chemical stability in a simulated pulp mill process stream, a targeted application for ESIX, was also prepared and tested

Evaluation of electrochemical ion exchange for cesium elution

International Nuclear Information System (INIS)

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

1996-04-01

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

Intercalation of gaseous thiols and sulfides into Ag+ ion-exchanged aluminum dihydrogen triphosphate.

Science.gov (United States)

Hayashi, Aki; Saimen, Hiroki; Watanabe, Nobuaki; Kimura, Hitomi; Kobayashi, Ayumi; Nakayama, Hirokazu; Tsuhako, Mitsutomo

2005-08-02

Ag(+) ion-exchanged layered aluminum dihydrogen triphosphate (AlP) with the interlayer distance of 0.85 nm was synthesized by the ion-exchange of proton in triphosphate with Ag(+) ion. The amount of exchanged Ag(+) ion depended on the concentration of AgNO(3) aqueous solution. Ag(+) ion-exchanged AlP adsorbed gaseous thiols and sulfides into the interlayer region. The adsorption amounts of thiols were more than those of sulfides, thiols with one mercapto group > thiol with two mercapto groups > sulfides, and depended on the amount of exchanged Ag(+) ion in the interlayer region. The thiols with one mercapto group were intercalated to expand the interlayer distance of Ag(+) ion-exchanged AlP, whereas there was no expansion in the adsorption of sulfide. In the case of thiol with two mercapto groups, there was observed contraction of the interlayer distance through the bridging with Ag(+) ions of the upper and lower sides of the interlayer region.

Treatment of low-activity-level process wastewaters by Continuous Countercurrent Ion Exchange

International Nuclear Information System (INIS)

Hall, R.; Watson, J.S.; Robinson, S.M.

1990-01-01

This paper discusses application of the Thomas model for predicting breakthrough curves from ion exchange column tests, methods for scale-up of experimental small-scaled ion exchange columns to industrial scale columns, and methods for predicting effluent compositions in a continuous countercurrent ion exchange system. 20 refs., 6 figs., 2 tabs

A Simple Apparatus for Fast Ion Exchange Separations

Energy Technology Data Exchange (ETDEWEB)

Samsahl, K

1964-09-15

An apparatus suitable for very fast ion exchange group separations in radiochemistry has been elaborated. The apparatus which consists of a system of glass tubes with pistons driven by the same force, allows the exact adjustment of influent solutions to a long series of ion-exchange columns. The practical application of the apparatus to the simultaneous separation of six groups of trace elements in the neutron activation analysis of biological material is described.

A Simple Apparatus for Fast Ion Exchange Separations

International Nuclear Information System (INIS)

Samsahl, K.

1964-09-01

An apparatus suitable for very fast ion exchange group separations in radiochemistry has been elaborated. The apparatus which consists of a system of glass tubes with pistons driven by the same force, allows the exact adjustment of influent solutions to a long series of ion-exchange columns. The practical application of the apparatus to the simultaneous separation of six groups of trace elements in the neutron activation analysis of biological material is described

Ion exchange in the 1980's in South Africa

International Nuclear Information System (INIS)

Giddey, T.B.S.

1981-01-01

In South Africa ion exchange plants have been modified into very sophisticated plants. This article looks at the development of- and application of resins and their manufacturing. At first it looks into how the equipment side has developed and changed in the last twenty years. High purity water production, desalination, waste water treatment and other applications of ion exchange in mineral recovery, like uranium, gold and base metals, and in chemical areas, like sugar processing, catalysis, tartaric acid and soda ash, are also discussed. Klipfontein Organic Products is setting up a plant to manufacture the whole range of ion exchange resins and thus to make SA needs to be independent of overseas suppliers of resin

Microbial treatment of ion exchange resins

International Nuclear Information System (INIS)

Kouznetsov, A.; Kniazev, O.

2001-01-01

A bioavailability of ion exchange resins to a microbial destruction as one of the alternative methods of compacting used ionites from the nuclear fuel manufacturing cycle enterprises has been investigated. The bio-destruction was studied after a preliminary chemical treatment or without it. A sensitivity of the ion exchange resins (including highly acidic cationite KU-2-8) to the microbial destruction by heterotrophic and chemo-litho-trophic microorganisms under aerobic conditions was shown in principle. The biodegradation of the original polymer is possible in the presence of the water soluble fraction of the resin obtained after its treatment by Fenton reagent and accelerated in the presence of Mn-ions in optimal concentration 1-2 g of Mn per liter of medium. Thus, the process of bio-destruction of ionite polymer by heterotrophic microorganisms can be compared with the bio-destruction of lignin or humic substances. The optimum parameters of bio-destruction and microorganisms used must be different for resins with different functional groups. (authors)

Ion exchange equilibrium for some uni-univalent and uni-divalent ...

African Journals Online (AJOL)

The study on thermodynamics of ion exchange equilibrium for uni-univalent Cl-/I-, Cl-/Br-, and uni-divalent Cl-/SO42-, Cl-/C2O42- reaction systems was carried out using ion exchange resin Duolite A-102 D. The equilibrium constant K was calculated by taking into account the activity coefficient of ions both in solution as well ...

Sorption kinetics of cesium on hydrous titanium dioxide

International Nuclear Information System (INIS)

Altas, Y.; Tel, H.; Yaprak, G.

2003-01-01

Two types of hydrous titanium dioxide possessing different surface properties were prepared and characterized to study the sorption kinetics of cesium. The effect of pH on the adsorption capacity were determined in both type sorbents and the maximum adsorption percentage of cesium were observed at pH 12. To elucidate the kinetics of ion-exchange reaction on hydrous titanium dioxide, the isotopic exchange rates of cesium ions between hydrous titanium dioxides and aqueous solutions were measured radiochemically and compared with each other. The diffusion coefficients of Cs + ion for Type1 and Type2 titanium dioxides at pH 12 were calculated as 2.79 x 10 -11 m 2 s -1 and 1.52 x 10 -11 m 2 s -1 , respectively, under particle diffusion controlled conditions. (orig.)

Kinetic theory for electron dynamics near a positive ion

International Nuclear Information System (INIS)

Wrighton, Jeffrey M; Dufty, James W

2008-01-01

A theoretical description of time correlation functions for electron properties in the presence of a positive ion of charge number Z is given. The simplest case of an electron gas distorted by a single ion is considered. A semi-classical representation with a regularized electron–ion potential is used to obtain a linear kinetic theory that is asymptotically exact at short times. This Markovian approximation includes all initial (equilibrium) electron–electron and electron–ion correlations through renormalized pair potentials. The kinetic theory is solved in terms of single-particle trajectories of the electron–ion potential and a dielectric function for the inhomogeneous electron gas. The results are illustrated by a calculation of the autocorrelation function for the electron field at the ion. The dependence on charge number Z is shown to be dominated by the bound states of the effective electron–ion potential. On this basis, a very simple practical representation of the trajectories is proposed and shown to be accurate over a wide range including strong electron–ion coupling. This simple representation is then used for a brief analysis of the dielectric function for the inhomogeneous electron gas

Plasma kinetics around a dust grain in an ion flow

International Nuclear Information System (INIS)

Maiorov, S.A.; Vladimirov, S.V.; Cramer, N.F.

2000-01-01

Full text: In a typical laboratory discharge, dust particles are negatively charged and usually levitate in the sheath or pre-sheath region under the balance of gravitational, electrostatic (due to the sheath electric field) and plasma (such as the ion drag) forces. The ion flow provides not only a direct (dragging) influence, but is also responsible for the generation of associated collective plasma processes which can strongly affect the vertical arrangement of the dust grains. The complete problem of the plasma dynamics around a macroscopic body in the presence of plasma flows is highly nonlinear and therefore its numerical analysis is of major importance. Among various numerical methods, direct integration of the equations of motion of the plasma particles represents a numerical experiment whose significance approaches experiments in the laboratory. Here, we present for the first time the results of a self-consistent molecular dynamics (MD) three-dimensional (3D) simulation of the kinetics of plasma particles (electrons and ions) around a dust grain, taking into account the dust charging. The core of the method includes consideration of the time evolution of the system consisting of positively ('ions') and negatively ('electrons') charged particles confined in a simulation box together with a macroscopic absorbing grain ('dust particle') with infinite mass and an initial (negative) charge. The ions are introduced in the system as a uniform flow defined by its Mach number and the ion temperature. The paths of the ions and electrons are determined through numerical integration of the equations of motion. We demonstrate that the plasma kinetics around a dust grain in the presence of an ion flow involves a strong ion focusing behind the grain. We have also confirmed that the most important of the processes involved is the ion time-scale; the kinetics of the electrons follows a Boltzmann distribution with good agreement. We note that the time constraints involved

Nonlocal exchange and kinetic-energy density functionals for electronic systems

International Nuclear Information System (INIS)

Glossman, M.D.; Rubio, A.; Balbas, L.C.; Alonso, J.A.

1992-01-01

The nonlocal weighted density approximation (WDA) to the exchange and kinetic-energy functionals of many electron systems proposed several years ago by Alonso and Girifalco is used to compute, within the framework of density functional theory, the ground-state electronic density and total energy of noble gas atoms and of neutral jellium-like sodium clusters containing up to 500 atoms. These results are compared with analogous calculations using the well known Thomas-Fermi-Weizsacker-Dirac (TFWD) approximations for the kinetic (TFW) and exchange (D) energy density functionals. An outstanding improvement of the total and exchange energies, of the density at the nucleus and of the expectation values is obtained for atoms within the WDA scheme. For sodium clusters the authors notice a sizeable contribution of the nonlocal effects to the total energy and to the density profiles. In the limit of very large clusters these effects should affect the surface energy of the bulk metal

Evaluation of ferrocyanide anion exchange resins regarding the uptake of Cs{sup +} ions and their regeneration

Energy Technology Data Exchange (ETDEWEB)

Won, Hui Jun; Mooon, Jei Kwon; Jung, Chong Hun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Chung, Won Yang [Kangwon University, Chuncheon (Korea, Republic of)

2008-10-15

Ferrocyanide-anion exchange resin was prepared and the prepared ion exchange resins were tested on the ability to uptake Cs{sup +} ion. The prepared ion exchange resins were resin-KCoFC, resin-KNiFC, and resin-KCuFC. The three tested ion exchange resins showed ion exchange selectivity on the Cs{sup +} ion of the surrogate soil decontamination solution, and resin- KCoFC showed the best Cs{sup +} ion uptake capability among the tested ion exchange resins. The ion exchange behaviors were explained well by the modified Dubinin-Polanyi equation. A regeneration feasibility study of the spent ion exchange resins was also performed by the successive application of hydrogen peroxide and hydrazine. The desorption of the Cs{sup +} ion from the ion exchange resin satisfied the electroneutrality condition in the oxidation step; the desorption of the Fe{sup 2+} ion in the reduction step could also be reduced by adding the K{sup +} ion.

Device for processing regenerative wastes of ion exchange resin

International Nuclear Information System (INIS)

Kuroda, Osamu; Ebara, Katsuya; Shindo, Toshikazu; Takahashi, Sankichi

1986-01-01

Purpose: To facilitate the operation and maintenance of a processing device by dividing radioactive wastes produced in the regenerative process of ion exchange resin into a regenerated usable recovery liquid and wastes. Constitution: Sulfuric acid is recovered by a diffusion dialysis method from wastes containing sulfuric acid that are generated in the regenerative process of cation-exchange resin and also caustic soda is recovered by the diffusion dialysis method from wastes containing caustic soda that are generated in the regenerative process of anion-exchange resin. The sulfuric acid and caustic soda thus recovered are used for the regeneration of ion-exchange resin. A concentrator is provided for concentrating the sulfuric acid and caustic soda water solution to concentration suitable for the regeneration of these ion-exchange resins. Also provided is a recovery device for recovering water generated from the concentrator. This device is of so simple a constitution that its operation and maintenance can be performed very easily, thereby greatly reducing the quantity of waste liquid required to be stored in drums. (Takahashi, M.)

Synthesis and ion-exchange properties of cerium(IV) molybdate

Energy Technology Data Exchange (ETDEWEB)

Srivastava, S K; Singh, Raj Pal; Agrawal, Sushma; Kumar, Satish [Roorkee Univ. (India). Dept. of Chemistry

1977-01-01

The synthesis, ion exchange properties, and the separation of a number of cation pairs on the columns of cerium (IV) molybdate is discussed. In order to obtain the product in gel form showing a high exchange capacity and suitable for column operation, preliminary experiments were performed to determine the optimum conditions of precipitation, i.e., the concentration of ceric and molybdate solutions, mixing ratio, pH of precipitation and the order of mixing. Cerium (IV) molybdate, prepared under the optimum conditions of concentration, acidity etc., shows exchange capacity of 0.96 meg per g of exchanger. The sorption of a large number of metal ions has been investigated and the compound shows promising behaviour as cation exchanger. Numerous separations of analytical and radiochemical interest have been performed on the column of this exchanger with great efficiency.

Synthesis and ion-exchange properties of cerium(IV) molybdate

International Nuclear Information System (INIS)

Srivastava, S.K.; Raj Pal Singh; Sushma Agrawal; Satish Kumar

1977-01-01

The synthesis, ion exchange properties, and the separation of a number of cation pairs on the columns of cerium (IV) molybdate is discussed. In order to obtain the product in gel form showing a high exchange capacity and suitable for column operation, preliminary experiments were performed to determine the optimum conditions of precipitation, i.e., the concentration of ceric and molybdate solutions, mixing ratio, pH of precipitation and the order of mixing. Cerium (IV) molybdate, prepared under the optimum conditions of concentration, acidity etc., shows exchange capacity of 0.96 meg per g of exchanger. The sorption of a large number of metal ions has been investigated and the compound shows promising behaviour as cation exchanger. Numerous separations of analytical and radiochemical interest have been performed on the column of this exchanger with great efficiency. (T.G.)

Ion exchange of strontium on synthetic hydroxyapatite

International Nuclear Information System (INIS)

Lazic, S.; Vukovic, Z.

1991-01-01

Adsorption of strontium ions on synthetic hydroxyapatite was examined using both batch and column methods. The apatite was prepared from aqueous solutions and characterized by standard analytical methods. The sample obtained had characteristics of well crystallized stoichiometric hydroxyapatite. The experimental data for sorption of strontium can be very well fitted with Langmuir's adsorption isotherm. It was found that sorption occurs by an ion exchange reaction between strontium ions in solution and calcium ions in apatite. (author) 14 refs.; 5 figs.; 1 tab

Thermal and chemical stabilities of some synthesized inorganic ion exchange materials

International Nuclear Information System (INIS)

EI-Naggar, I.M.; Abou-Mesalam, M.M.; El-Shorbagy, M.M.; Shady, S.A.

2006-01-01

Chromium and cerium titanate as inorganic ion exchange materials were synthesized by the reaction of potassium chromate or ammonium eerie nitrate with titanium tetrachloride with molar ratio equal unity. The crystal system of both chromium and cerium titanates were determined and set to be monoclinic and orthorhombic system's, respectively. The chemical composition of both chromium and cerium titanates was determined by X-ray fluorescence technique and based on the data obtained with other different techniques. A molecular formula for chromium and cerium titanates as Cr 2 Ti 12 O 27 . 13H 2 O and Ce 2 Ti 3 O 10 . 7.46H 2 O, respectively, was proposed. Thermal stabilities of both ion exchangers were investigated at different heating temperatures. Also the stability of chromium and cerium titanates for chemical attack was studied in different media. The data obtained showed high thermal and chemical stabilities of chromium and cerium titanate ion exchangers compared with the same group of ion exchange materials. The ion exchange capacities of chromium and cerium titanates at different heating temperature were also investigated

Thermal and chemical stabilities of some synthesized inorganic ion exchange materials

International Nuclear Information System (INIS)

El-Naggar, I.M.; Abou-Mesalam, M. M.; El-Shorbagy, M.M.; Shady, S.A.

2005-01-01

Chromium and cerium titanate as inorganic ion exchange materials were synthesized by the reaction of potassium chromate or ammonium ceric nitrate with titanium tetrachloride with molar ratio equal unity. The crystal system of both chromium and cerium titanates were determined and set to be monoclinic and orthorhombic systems, respectively. The chemical composition of both chromium and cerium titanates were determined by X-ray fluorescence technique and based on the data obtained with other different techniques. We can proposed molecular formula for chromium and cerium titanates as Cr 2 Ti 1 2O27. 13H 2 O and Ce 2 ThO10. 7.46 H 2 O, respectively. Thermal stability of both ion exchangers was investigated at different heating temperatures. Also the stability of chromium and cerium titanates for chemical attack was studied in different media. The data obtained showed high thermal and chemical stabilities of chromium and cerium titanate ion exchangers compared to the same group of ion exchange materials. The ion exchange capacities of chromium and cerium titanates at different heating temperature were investigated

Kinetic and Thermodynamic Studies for the Removal of Europium Ions from Waste Solution Using Some Local Clay Minerals

International Nuclear Information System (INIS)

El-Kamash, A.M.; El-Masry, E.H.; El-Dessouky, M.I.

2008-01-01

Thermodynamic and kinetic investigations on the removal of Eu 3+ ions from aqueous waste solution using bentonite and sandstone, as local clay minerals, has been done using batch technique. The influences of ph, contact time between liquid and solid phases, initial metal ion concentration, and temperature have been evaluated. Pseudo first-order and pseudo second-order kinetic models were used to analyze the sorption rate data and the results showed that the pseudo second-order model is best correlate the kinetic data. Equilibrium isotherms were determined to assess the maximum sorption capacity of bentonite and sandstone and the equilibrium sorption data were analyzed using Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherm models. All tested models fit the data reasonably well in terms of regression coefficients. The maximum sorption capacity of bentonite was found to be greater than that of sandstone and the mean free energy is in all cases in the range corresponding to the ion exchange type of sorption. Sorption studies were also performed at different temperatures to obtain the thermodynamic parameters of the process. The numerical value of δG degree decreases with an increase in temperature, indicating that the sorption reaction is more favorable at higher temperature. The positive values of δH degree correspond to the endothermic nature of the sorption process

Kinetics of exchange of a tracer in soil and clay samples

Energy Technology Data Exchange (ETDEWEB)

Zanotti, J C; Facetti, J F [Asuncion Nacional Univ. (Paraguay). Inst. de Ciencias

1971-01-01

The kinetics of exchange of a Na tracer in soil and clay samples, provides with a reliable and convenient method for the determination of the different soil fraction ahd their CEC values, In addition, the analysis of the exchanges curves can be used for the identification of the clay present in the soil.

Kinetics of exchange of a tracer in soil and clay samples

International Nuclear Information System (INIS)

Zanotti, J.C.; Facetti, J.F.

1971-01-01

The kinetics of exchange of a Na tracer in soil and clay samples, provides with a reliable and convenient method for the determination of the different soil fraction ahd their CEC values, In addition, the analysis of the exchanges curves can be used for the identification of the clay present in the soil

Ion exchange in ZSM-5 zeolite

International Nuclear Information System (INIS)

Matthews, D.P.; Rees, L.V.C.

1986-01-01

The ion exchange properties of Na-ZSM5 have been studied using a number of univalent and divalent cations at 25degC and 65degC. All the univalent cations studied achieved 100 per cent exchange. The thermodynamic affinity sequence Cs > Rb=NH 4 =H 3 O>K>Na>Li was found at both temperatures for a sample with Si/Al=39. Standard enthalpies of exchange ΔH o were calculated using the van't' Hoff isochore and standard entropies of exchange were then calculated from ΔH o and ΔG o . Multivalent cations were unable to achieve 100 per cent exchange. The maximum exchange was found to increase through the series Ca 2+ cations ( 57 Fe enriched) on dehydration and rehydration following sorption and desorption of ethanol. At least 3 sites for Fe 2+ were observed in the dehydrated zeolite. (author)

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

International Nuclear Information System (INIS)

Navrotsky, Alexandra; Liu, Qinyuan

2004-01-01

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

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

Science.gov (United States)

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

2015-01-01

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

Electrically switched cesium ion exchange. FY 1997 annual report

International Nuclear Information System (INIS)

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

1997-09-01

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

Spectator Ions ARE Important! A Kinetic Study of the Copper-Aluminum Displacement Reaction

Science.gov (United States)

Sobel, Sabrina G.; Cohen, Skyler

2010-01-01

Surprisingly, spectator ions are responsible for unexpected kinetics in the biphasic copper(II)-aluminum displacement reaction, with the rate of reaction dependent on the identity of the otherwise ignored spectator ions. Application of a published kinetic analysis developed for a reaction between a rotating Al disk and a Cu(II) ion solution to the…

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

Energy Technology Data Exchange (ETDEWEB)

Choi, Seong-Ho; Jeong, Young Han; Ryoo, Jae Jeong; Lee, Kwang-Pill [Department of Chemistry Graduate School, Kyungpook National University, Taegu (Korea)

2000-07-01

Ion-exchange membranes modified with triethylamine [-N(CH{sub 2}CH{sub 3}){sub 3}] and phosphoric acid (-PO{sub 3}H) groups were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto 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 and XPS. The ion-exchange capacities of the cation- and anion-exchange membrane were 0.20 and 1.24mmol/g, respectively. The content of cation- and anion exchange group increased with increasing grafting yield (d.g.=100%). Electrical resistance of PNF modified with TEA and -PO{sub 3}H group decreased with increasing ion-exchange group capacities. Application of the graft-type ion-exchange membranes as separators for electrodialysis enabled use to reduce the time required to achieve 85.5% desalination of the 0.5M NaCl solution. (author)

Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

Energy Technology Data Exchange (ETDEWEB)

Adachi, Tetsurou (Nitto Denko Corp., Ibaraki, Osaka (Japan)); Sawa, Toshio; Shindoh, Toshikazu

1989-09-01

The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author).

Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

International Nuclear Information System (INIS)

Adachi, Tetsurou; Sawa, Toshio; Shindoh, Toshikazu.

1989-01-01

The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author)

Sinusoidal voltage protocols for rapid characterisation of ion channel kinetics.

Science.gov (United States)

Beattie, Kylie A; Hill, Adam P; Bardenet, Rémi; Cui, Yi; Vandenberg, Jamie I; Gavaghan, David J; de Boer, Teun P; Mirams, Gary R

2018-03-24

Ion current kinetics are commonly represented by current-voltage relationships, time constant-voltage relationships and subsequently mathematical models fitted to these. These experiments take substantial time, which means they are rarely performed in the same cell. Rather than traditional square-wave voltage clamps, we fitted a model to the current evoked by a novel sum-of-sinusoids voltage clamp that was only 8 s long. Short protocols that can be performed multiple times within a single cell will offer many new opportunities to measure how ion current kinetics are affected by changing conditions. The new model predicts the current under traditional square-wave protocols well, with better predictions of underlying currents than literature models. The current under a novel physiologically relevant series of action potential clamps is predicted extremely well. The short sinusoidal protocols allow a model to be fully fitted to individual cells, allowing us to examine cell-cell variability in current kinetics for the first time. Understanding the roles of ion currents is crucial to predict the action of pharmaceuticals and mutations in different scenarios, and thereby to guide clinical interventions in the heart, brain and other electrophysiological systems. Our ability to predict how ion currents contribute to cellular electrophysiology is in turn critically dependent on our characterisation of ion channel kinetics - the voltage-dependent rates of transition between open, closed and inactivated channel states. We present a new method for rapidly exploring and characterising ion channel kinetics, applying it to the hERG potassium channel as an example, with the aim of generating a quantitatively predictive representation of the ion current. We fitted a mathematical model to currents evoked by a novel 8 second sinusoidal voltage clamp in CHO cells overexpressing hERG1a. The model was then used to predict over 5 minutes of recordings in the same cell in response to

Samarium ion exchanged montmorillonite for high temperature cumene cracking reaction

International Nuclear Information System (INIS)

Binitha, N.N.

2009-01-01

Full text: Nano material 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 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 Bronsted acidity is confirmed from high selectivity to benzene. (author)

Method of solidifying radioactive ion exchange resin

International Nuclear Information System (INIS)

Minami, Yuji; Tomita, Toshihide

1989-01-01

Spent anion exchange resin formed in nuclear power plants, etc. generally catch only a portion of anions in view of the ion exchange resins capacity and most of the anions are sent while possessing activities to radioactive waste processing systems. Then, the anion exchange resins increase the specific gravity by the capture of the anions. Accordingly, anions are caused to be captured on the anion exchange resin wastes such that the specific gravity of the anion exchange resin wastes is greater than that of the thermosetting resins to be mixed. This enables satisfactory mixing with the thermosetting resins and, in addition, enables to form integral solidification products in which anion exchange resins and cation exchange resins are not locallized separately and which are homogenous and free from cracks. (T.M.)

Isotherms of ion exchange on titanates of alkaline metals

International Nuclear Information System (INIS)

Fillina, L.P.; Belinskaya, F.A.

1986-01-01

Present article is devoted to isotherms of ion exchange on titanates of alkaline metals. Therefore, finely dispersed hydrated titanates of alkaline metals (lithium, sodium, potassium) with ion exchange properties are obtained by means of alkaline hydrolysis of titanium chloride at high ph rates. Sorption of cations from salts solution of Li 2 SO 4 , NaNO 3 , Ca(NO 3 ) 2 , AgNO 3 by titanates is studied.

A structural study of nepheline hydrate I, an inorganic ion exchanger

International Nuclear Information System (INIS)

Hansen, S.

1985-01-01

The crystal structures of nepheline hydrates I, Na 3 Al 3 Si 3 O 12 x 2H 2 O, and three compounds produced by ion exchange with aqueous KCl, RbCl and CsCl at 80 degrees C, have been studied using X-ray diffraction methods. This synthetic silicate has a tetrahedral framework with a two-dimensional pore system consisting of perpendicular 8-ring and 6-ring channels. The long-range ordering of Si and Al into adjacent tetrahedra is well developed. Some aspects of the topology, geometry and bonding of the tetrahedral frame are discussed. Related framework types are derived by unit cell twinning of the idealized cristobalite structure. A limit in the ion exchange is observed when about 1/3 of the Na + ions have been replaced. This behaviour is explained by the restricted volume of two Na sites situated in the 6-ring channel. The readily exchangeable ions and water molecules in the 8-ring channels an arrangement which gradually changes when the size of the alkali metal-ion increases. Most K + -exchanged crystals have a unit cell which is determined by the translational symmetry of the framework, while the original Na form has a two-fold superstructure and the Rb + -exchanged form has a five-fold superstructure. Caesium-ion-exchanged crystals have incommensurate structures. The occurrence of superstructures is related to long-range ordering of the species in the 8-ring channels. (author)

Kinetic and equilibrium study for the sorption of Pb(II) ions from ...

African Journals Online (AJOL)

Kinetic and equilibrium study for the sorption of Pb(II) ions from aqueous phase by water hyacinth ( Eichhornia crassipes ) ... Bulletin of the Chemical Society of Ethiopia ... Abstract. This paper reports the kinetic and equilibrium studies of Eichhornia crassipes root biomass as a biosorbent for Pb(II) ions from aqueous system.

The selectivity of zirconium phosphate for caesium in electrochemical ion exchange

International Nuclear Information System (INIS)

Lain, M.J.

1988-11-01

The properties of amorphous zirconium phosphate are investigated as an inorganic ion exchanger for use in liquid waste treatment by electrochemical ion exchange. Experiments to determine and increase the selectivity for caesium exchange over sodium are discussed, including various pulsed waveforms and studies with rotating membranes. Automation of a sampling system with pH and atomic absorption measurements is described. (author)

Morphology and annealing kinetics of ion tracks in minerals

Directory of Open Access Journals (Sweden)

Ewing R. C.

2012-10-01

Full Text Available We have studied the morphology and annealing kinetics of ion tracks in Durango apatite using synchrotron small angle X-ray scattering. The non-destructive, artefact-free technique enables us to determine the track radii with a resolution of fractions of a nanometre. The tracks were generated using different heavy ions with energies between 185 MeV and 2.6 GeV. The track morphology is consistent with the formation of long cylindrical amorphous tracks. The annealing kinetics, measured by SAXS in combination with ex situ and in situ annealing experiments, suggests structural relaxation followed by recrystallisation of the damaged material. The measurement methodology shown here provides a new means for in-depth studies of ion-track formation in minerals under a wide variety of geological conditions.

Electrospun Zeolite/Cellulose Acetate Fibers for Ion Exchange of Pb2+

Directory of Open Access Journals (Sweden)

Daniel N. Tran

2014-12-01

Full Text Available The ion exchange capability of electrospun cellulose acetate (CA fibers containing zeolite A nanoparticles is reported. Solid and porous CA fibers were used to make a zeolite-embedded filter paper, which was then used to ion exchange Na+ with Cu2+ and Pb2+. The composite Linde Type A (LTA zeolite CA fibers exchanged 0.39 mmol/g more Pb2+ than LTA nanoparticles in the solid CA fibers. These fibers could provide a simple and effective method for heavy metal ion removal in water.

Rupture loop annex ion exchange RLAIX vault deactivation

Energy Technology Data Exchange (ETDEWEB)

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

1996-08-01

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

Ion exchange for treatment of industrial effluents

International Nuclear Information System (INIS)

Moreno Daudinot, Aurora Maria; Ge Leyva, Midalis

2016-01-01

The acid leaching and ammoniacal carbonate technologies of laterite respectively, are responsible for the low quality of life of the local population, the big deforested areas due to the mining tilling, the elevated contents of solids in the air and waters, as well as the chemical contamination by metals presence, the acidity or basicity of the effluents of both industries, that arrive through the river and the bay to aquifer's mantle. The ion exchange resins allow ions separation contained in low concentrations in the solutions, where the separation of these elements for solvents, extraction or another chemical methods would be costly. Technological variants are proposed in order to reduce the impact produced on the flora and the fauna, by the liquid effluents of nickel industry, by means of ion exchange resins introduction as well as the recuperation of metals and their re incorporation to the productive process. (Author)

Distribution of Components in Ion Exchange Materials Taken from the K East Basin and Leaching of Ion Exchange Materials by Nitric/Hydrofluoric Acid and Nitric/Oxalic Acid

International Nuclear Information System (INIS)

Delegard, C.H.; Rinehart, D.E.; Hoopes, F.V.

1998-01-01

Laboratory tests were performed to examine the efficacy of mixed nitric/hydrofluoric acid followed by mixed nitric/oxalic acid leach treatments to decontaminate ion exchange materials that have been found in a number of samples retrieved from K East (KE)Basin sludge. The ion exchange materials contain organic ion exchange resins and zeolite inorganic ion exchange material. Based on process records, the ion exchange resins found in the K Basins is a mixed-bed, strong acid/strong base material marketed as Purolite NRW-037. The zeolite material is Zeolon-900, a granular material composed of the mineral mordenite. Radionuclides sorbed or associated with the ion exchange material 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). Elutriation and washing steps are designed to remove the organic resins from the K Basin sludge. To help understand the effects of the anticipated separation steps, tests were performed with well-rinsed ion exchange (IX) material from KE Basin floor sludge (sample H-08 BEAD G) and with well-rinsed IX having small quantities of added KE canister composite sludge (sample KECOMP). Tests also were performed to determine the relative quantities of organic and inorganic IX materials present in the H-08 K Basin sludge material. Based on chemical analyses of the separated fractions, the rinsed and dry IX material H-08 BEAD G was found to contain 36 weight percent inorganic material (primarily zeolite). The as-received (unrinsed) and dried H-08 material was estimated to contain 45 weight percent inorganic material

Extraction of Co ions from ion-exchange resin by supercritical carbon dioxide

International Nuclear Information System (INIS)

Ju, Min Su; Koh, Moon Sung; Yang, Sung Woo; Park, Kwang Heon; Kim, Hak Won; Kim, Hong Doo

2005-01-01

There are a number of liquid treatment processes for eliminating radioactive ionic contaminants in nuclear facilities. One of the most common treatment methods for aqueous streams is the use of ion exchange, which is a well-developed technique that has been employed for many years in the nuclear industry. More specifically speaking, systems that ion exchange method is applied to in nuclear power plants are liquid radioactive waste treatment system, chemical and volume control system, steam generator blowdown treatment system, and service water supply system. During the operation of nuclear power plants, radioactive contaminants such as Co-60, Mn-54, Fe-59 and Cs-137 are contained in liquid radioactive wastes. And the wastes containing small amount of uranium are generated in nuclear fuel cycle facilities. To treat the liquid radioactive waste, we usually install ion exchangers rather than evaporators due to their simplicity and effectiveness, and this trend is increasing. However, the ion exchange process produces large volume of spent organic resin, and has some problems of radiation damage and thermal instability. And the reuse of the resin is limited due to the degradation of ion-exchanging ability. For this reason, were should consider a better method to expand the lifetime of the resin or to reduce the volume of radioactive resin wastes by extracting radioactive contaminants located in the resin. Supercritical fluid CO 2 has many good points as a process solvent that include low viscosity, negligible surface tension, and variable selectivity. And supercritical fluids have physical properties of both liquid and gas such as good penetration with a high dissolution capability. Supercritical fluids have been widely used in extraction, purification, and recovery processes. A number of workers applied supercritical CO 2 solvent for cleaning of precision devices and waste treatments. Since supercritical CO 2 has its mild critical point at 31 and 73.8bar as .deg. C

Ion exchange filter transition plan for BWRs and PWRs

International Nuclear Information System (INIS)

Garcia, Susan; McElrath, Joel; Varnam, Jeremie; Giannelli, Joseph F.

2014-01-01

Analysis and quantification of reactor water, feedwater, and chemical and volume control system (CVCS) soluble metals and radioisotopes are essential for monitoring species that impact fuel performance, steam generator and heat exchanger performance, mitigation of stress corrosion cracking of reactor piping and internals, radiation fields and ensuring that dose mitigation techniques are effective. Soluble species in the CVCS, feedwater, reactor water and other process sample streams are usually collected on ion exchange membranes after the sample has passed through a 0.45 or 0.1 μm membrane filter. Cationic species are predominantly of interest. Most nuclear plants currently use cation exchange membranes from Toray Industries, Inc. In September 2012, it was reported that Toray Industries, Inc. would discontinue the manufacturing of cation exchange membranes at the end of 2012. Similar reports were received concerning ion exchange membranes manufactured by Pall Corporation. These reports prompted several plants and utilities to begin evaluating other products from various vendors to replace their current ion exchange membranes in preparation for a transition. With this possible change having a potential impact on the water chemistry analyses that are important for monitoring fuel reliability and corrosion and dose control, an initial scoping evaluation of ion exchange membrane availability from various vendor and plant experiences was conducted. Recommended approaches were provided to close identified gaps and reduce burden on nuclear plant chemistry laboratories. Additional work required in 2014, includes an independent laboratory review of membrane performance and in-plant demonstrations. These demonstrations and evaluations will assist the industry by providing the technical input needed to manage a change in membrane use so that preferred processes and media can be identified to minimize any adverse impacts on chemistry analyses that support chemistry control

Respective influence of thermodynamic, hydrodynamic and diffusion factors on ion exchanger operation. Application to the ion exchanger NYMPHEA

International Nuclear Information System (INIS)

Nicoud, R.M.

1987-01-01

Nymphea is an annular ion exchanger, with a resin bed 30 centimeter-thick, used for purification of the water from the spent fuel storage pool at La Hague reprocessing plant. Very low concentration solutions (10 -12 eq/l for cobalt) are purified by Nymphea, and parameter must be extrapolated from the range 0.01 - 0.0001 eq/l to very low concentrations. A model is developed, describing ion state inside the grains. The limiting step in Nymphea operation is external diffusion. Diffusion time is determined by mean grain size which should be accurately defined for extrapolation of results from monodispersed distribution (often the case in laboratories) to polydispersed (often the case in industry). Operation of an ion exchanger can be simulated for any ion number in solution. In steady state condition of concentration pool purification increases with flow rate. Simulation in transient operation allows the determination of all the concentrations in function of time and hence to calculate the time to reach the maximum permissible concentration for cobalt. This time depends upon calcium pollution (by fuel can dissolution, atmospheric pollution) which is not accurately known [fr

Investigation of ion kinetic effects in direct-drive exploding-pusher implosions at the NIF

Energy Technology Data Exchange (ETDEWEB)

Rosenberg, M. J., E-mail: mrosenbe@mit.edu; Zylstra, A. B.; Séguin, F. H.; Rinderknecht, H. G.; Frenje, J. A.; Gatu Johnson, M.; Sio, H.; Waugh, C. J.; Sinenian, N.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); McKenty, P. W.; Hohenberger, M.; Radha, P. B.; Delettrez, J. A.; Glebov, V. Yu.; Betti, R.; Goncharov, V. N.; Knauer, J. P.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); and others

2014-12-15

Measurements of yield, ion temperature, areal density (ρR), shell convergence, and bang time have been obtained in shock-driven, D{sub 2} and D{sup 3}He gas-filled “exploding-pusher” inertial confinement fusion (ICF) implosions at the National Ignition Facility to assess the impact of ion kinetic effects. These measurements probed the shock convergence phase of ICF implosions, a critical stage in hot-spot ignition experiments. The data complement previous studies of kinetic effects in shock-driven implosions. Ion temperature and fuel ρR inferred from fusion-product spectroscopy are used to estimate the ion-ion mean free path in the gas. A trend of decreasing yields relative to the predictions of 2D DRACO hydrodynamics simulations with increasing Knudsen number (the ratio of ion-ion mean free path to minimum shell radius) suggests that ion kinetic effects are increasingly impacting the hot fuel region, in general agreement with previous results. The long mean free path conditions giving rise to ion kinetic effects in the gas are often prevalent during the shock phase of both exploding pushers and ablatively driven implosions, including ignition-relevant implosions.

Ion Exchange Temperature Testing with SRF Resin - 12088

Energy Technology Data Exchange (ETDEWEB)

Russell, R.L.; Rinehart, D.E.; Brown, G.N.; Peterson, R.A. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

2012-07-01

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 Cs-137. Recent proposed changes to the WTP ion exchange process baseline indicate that higher temperatures (50 deg. C) to alleviate post-filtration precipitation issues prior to reaching the ion exchange columns may be required. 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 elevated temperature on resin loading and resin degradation during extended solution flow at elevated temperature (45 deg., 50 deg., 55 deg., 60 deg., 65 deg., 75 deg. C). Testing for extended times at elevated temperatures showed that the resin does degrade and loading capacity is reduced at and above 45 deg. C. Above 60 deg. C the resin appears to not load at all. It was observed that the resin disintegrated at 75 deg. C until not much was left and partially disintegrated at 65 deg. C, which caused the column to plug in both tests after ∼336 hours. The results indicate that WTP will lose resin loading capacity if the ion exchange process is performed above 25 deg. C, and the resin will disintegrate above 65 deg. C. Therefore, WTP will have a restricted operating range of temperatures to perform the ion exchange process with this resin. PNNL and WTP are currently evaluating the operating limits of the resin in further detail. Aging in 0.5 M HNO{sub 3} also caused the resin to lose capacity above 25 deg. C and to completely dissolve at 55 deg. C. Again, WTP will have a restricted operating range of temperatures when eluting the resin with nitric acid in order to maintain resin loading capacity and avoid disintegration of the resin

Modality analysis of anchored ion exchange tower using Ansys

International Nuclear Information System (INIS)

Li Liang; Lei Zeyong

2008-01-01

Ion exchange towers are exposed to serious damage in the event of earthquakes. It is very necessary to study the seismic resistance of ion exchange tower. A finite element model of anchored ion exchange tower was made by Ansys. The first 10 ranks of inherent frequencies were made out, and three-dimensional main vibratory model figures were drawn out. The maximal stress along x-axis and y-axis and the main displacement were found at the bottom part of the wall of tower junction with the pillars. It is concluded that the breakage of tower wall easily occurs at the bottom part of the wall of tower junction with the pillars. Therefore, it is very important to reinforce the junction of the tower body, and the strengthening plate should lie near the bottom of wall. (authors)

On the mechanism of ion exchange in zirconium phosphates

International Nuclear Information System (INIS)

Clearfield, A.; Frianeza, T.N.

1978-01-01

α-titanium phosphate, Ti(HPO 4 ) 2 .H 2 O, was found to form two sodium ion exchanged phases. A half exchanged phase of ideal composition TiNaH(PO 4 ) 2 .4H 2 O formed first. However, before all of the titanium phosphate was converted to this phase a second phase of higher Na + content formed. Thus, a three phase solid existed until sufficient sodium ion uptake (approximately 5.5 meq/g) produced only the two exchanged phases. Finally, the half exchanged phase was converted to the more highly loaded one and this latter phase existed from 6 to 8 meq/g of Na + uptake. Severe disordering of the crystal lattice during exchange is proposed to explain this unusual exchange behavior. A broad range of titanium phosphate-zirconium phosphate solid solutions was found to form. Their behavior towards Na + -H + exchange was determined and interpreted on the basis of the known behavior of the pure phases. Mixed Ti-Zr solid solutions of their pyrophosphates were obtained at elevated temperatures. (author)

"One-Pot" Ion-Exchange and Mesopore Formation During Desilication

DEFF Research Database (Denmark)

Holm, Martin Spangsberg; Hansen, Martin Kalmar; Christensen, Claus Hviid

2009-01-01

A desilication protocol using tetramethylammonium hydroxide was applied to zeolite beta. The new route presented here integrates the desilication and ion-exchange post-treatment steps allowing for a subsequent ion-exchange step to be avoided. It is shown that the acidic and highly mesoporous zeol...... zeolite is obtained directly upon calcination. Thus, careful choice of base and post-treatment conditions lead to the fabrication of a hierarchical meso- and microporous structure with completely retained crystallinity. (...

Energy Properties of Ion Acoustic Waves in Stable and Unstable Plasmas

DEFF Research Database (Denmark)

Jensen, Vagn Orla; Lynov, Jens-Peter

1979-01-01

Energy exchange between potential energy and ion kinetic energy in an ion acoustic wave is considered. In order to investigate the linear Landau damping or growth, the energy is calculated by use of first‐order quantities only so that nonlinear effects are not involved. It is found that for ion...... acoustic waves that are growing or damped in space the time average of the sum of the potential and the kinetic energy density is independent of position. Energy absorption spectra in particle velocity space are calculated; they are relatively broad and complicated functions. This shows that plasma ions...... of all velocities exchange energy with the wave....

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

International Nuclear Information System (INIS)

Ham, J.E.

1996-01-01

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

On the mechanism of ion exchange in zirconium phosphates

International Nuclear Information System (INIS)

Kullberg, L.; Clearfield, A.

1981-01-01

An equilibrium study of the Na + -Cs + -H + exchange on crystalline α-zirconium phosphate has been carried out. Isotherms for the ion exchange have been determined and phases formed during the exchange have been identified. The surface groups of the exchanger were found to greatly prefer cesium to sodium. For exchange in the interior, cesium was found to be preferred to sodium for 0 to 50% of exchange, while sodium is slightly preferred to cesium for the second half of exchange. The influence of surface equilibria on the total exchange mechanism is discussed. (author)

Mechanism of central ion exchange between ytterbium(3) and neodymium(3) diethylenetriaminepentaacetate in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Nikitenko, S.I.; Martynenko, L.I.; Pechurova, N.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

1984-11-01

Kinetics and exchange mechanism in the NdL/sup 2 -/Yb/sup 3 +/ system, where L/sup 5 -/ is diethylene triaminepentaacetate-ion, are studied spectrophotometrically. It is shown that in the pH range of 4.0-4.5 the exchange occurs according to dissociative mechanism with the formation of biprotonated intermediate complexes. In the pH 4.5-5.0 range the formation of monoprotonated inermediates is possible. At pH values of 5.0-6.0 the exchange is mainly performed according to the associative mechanism with the formation of biprotonated intermediate complexes. In the pH 4.5-5.0 range the formation of monoprotonated intermediates is possible. At pH values of 5.0-6.0 the exchange is mainly performed according to the associative mechanism. It is found that under conditions of the experiment the binuclear complex of the ((YbL)Nd)/sup +/ composition is the association mechanism exchange product. It is also formed in the case of mixing YbL/sup 2 -/ and Nd/sup 3 +/. Rate constants of exchange according to dissociative mechanism and constant of intraspheric isomerization ((NdL)Yb)/sup +/ ..-->.. ((YbL)Nd)/sup +/ are calculated. Stability constants of ((NdL)Yb)/sup +/ and ((YbL)Nd)/sup +/ are determined.

Ion Exchange Column Tests Supporting Technetium Removal Resin Maturation

Energy Technology Data Exchange (ETDEWEB)

Nash, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McCabe, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hamm, L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Smith, F. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Morse, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2013-12-20

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

Ultrafiltration Membrane Fouling and the Effect of Ion Exchange Resins

KAUST Repository

Jamaly, Sanaa

2011-12-01

Membrane fouling is a challenging process for the ultrafiltration membrane during wastewater treatment. This research paper determines the organic character of foulants of different kinds of wastewater before and after adding some ion exchange resins. Two advanced organic characterization methods are compared in terms of concentration of dissolved organic carbons: The liquid chromatography with organic carbon (LC-OCD) and Shimadzu total organic carbon (TOC). In this study, two secondary wastewater effluents were treated using ultrafiltration membrane. To reduce fouling, pretreatment using some adsorbents were used in the study. Six ion exchange resins out of twenty were chosen to compare the effect of adsorbents on fouling membrane. Based on the percent of dissolved organic carbon’s removal, three adsorbents were determined to be the most efficient (DOWEX Marathon 11 anion exchange resin, DOWEX Optipore SD2 polymeric adsorbent, and DOWEX PSR2 anion exchange), and three other ones were determined to the least efficient (DOWEX Marathon A2 anion exchange resin, DOWEX SAR anion exchange resin, and DOWEX Optipore L493 polymeric adsorbent). Organic characterization for feed, permeate, and backwash samples were tested using LC-OCD and TOC to better understand the characteristics of foulants to prevent ultrafiltration membrane fouling. The results suggested that the polymeric ion exchange resin, DOWEX SD2, reduced fouling potential for both treated wastewaters. All the six ion exchange resins removed more humic fraction than other organic fractions in different percent, so this fraction is not the main for cause for UF membrane fouling. The fouling of colloids was tested before and after adding calcium. There is a severe fouling after adding Ca2+ to effluent colloids.

Electrostatic influence of local cysteine environments on disulfide exchange kinetics.

Science.gov (United States)

Snyder, G H; Cennerazzo, M J; Karalis, A J; Field, D

1981-11-10

The ionic strength dependence of the bimolecular rate constant for reaction of the negative disulfide 5,5'-dithiobis (2-nitrobenzoic acid) with cysteines in fragments of naturally occurring proteins was determined by stopped-flow spectroscopy. The Debye-Hückel relationship was applied to determine the effective charge at the cysteine and thereby determine the extent to which nearby neighbors in the primary sequence influence the kinetics. Corrections for the secondary salt effect on cysteine pKs were determined by direct spectrometric pH titration of sulfhydryl groups or by observation of the ionic strength dependence of kinetics of cysteine reaction with the neutral disulfide 2,2'-dithiodipyridine. Quantitative expressions was verified by model studies with N-acetyl-cystein. At ionic strengths equal to or greater than 20 mM, the net charge at the polypeptide cysteine site is the sum of the single negative charge of the thiolate anion and the charges of the amino acids immediately preceding and following the cysteine in the primary sequence. At lower ionic strengths, more distant residues influence kinetics. At pH 7.0, 23 degree C, and an ionic strength of 20 mM, rate constants for reaction of the negative disulfide with a cysteine having two positive neighbors, one positive and one neutral neighbor, or two neutral neighbors are 132000, 3350, and 367 s-1 M-1, respectively. This corresponds to a contribution to the activation energy of 0.65- 1.1 kcal/mol per ion pair involved in collision between the cysteine and disulfide regions. The results permit the estimation that cysteine local environments may provide a means of achieving a 10(6)-fold range in rate constants in disulfide exchange reactions in random-coil proteins. This range may prove useful in developing strategies for directing disulfide pairing in synthetic proteins.

Simultaneous removal of perchlorate and arsenate by ion-exchange media modified with nanostructured iron (hydr)oxide

Energy Technology Data Exchange (ETDEWEB)

Hristovski, Kiril [Environmental Technology Laboratory, Arizona State University, 6075 S. WMS Campus Loop W, Mesa, AZ 85212 (United States)], E-mail: kiril.hristovski@asu.edu; Westerhoff, Paul [Department of Civil and Environmental Engineering, Arizona State University, Box 5306, Tempe, AZ 85287-5306 (United States)], E-mail: p.westerhoff@asu.edu; Moeller, Teresia [SolmeteX Inc., 50 Bearfoot Road, Northborough, MA 01532 (United States)], E-mail: tmoller@solmetex.com; Sylvester, Paul [SolmeteX Inc., 50 Bearfoot Road, Northborough, MA 01532 (United States)], E-mail: psylvester@solmetex.com; Condit, Wendy [Battelle, 505 King Avenue, Columbus, OH 43201 (United States)], E-mail: conditw@battelle.org; Mash, Heath [United States Environmental Protection Agency, 26W. Martin Luther King Dr., Cincinnati, OH 45268 (United States)], E-mail: mash.heath@epa.gov

2008-03-21

Hybrid ion-exchange (HIX) media for simultaneous removal of arsenate and perchlorate were prepared by impregnation of non-crystalline iron (hydr)oxide nanoparticles onto strong base ion-exchange (IX) resins using two different chemical treatment techniques. In situ precipitation of Fe(III) (M treatment) resulted in the formation of sphere-like clusters of nanomaterials with diameters of {approx}5 nm, while KMnO{sub 4}/Fe(II) treatments yielded rod-like nanomaterials with diameters of 10-50 nm inside the pores of the media. The iron content of most HIX media was >10% of dry weight. The HIX media prepared via the M treatment method consistently exhibited greater arsenate adsorption capacity. The fitted Freundlich adsorption intensity parameters (q=KxC{sub E}{sup 1/n}) for arsenate (1/n < 0.6) indicated favorable adsorption trends. The K values ranged between 2.5 and 34.7 mgAs/g dry resin and were generally higher for the M treated media in comparison to the permanganate treated media. The separation factors for perchlorate over chloride ({alpha}{sub Cl{sup -}}{sup ClO{sub 4}{sup -}}) for the HIX media were lower than its untreated counterparts. The HIX prepared via the M treatment, had higher {alpha}{sub Cl{sup -}}{sup ClO{sub 4}{sup -}} than the HIX obtained by the KMnO{sub 4}/Fe(II) treatments suggesting that permanganate may adversely impact the ion-exchange base media. Short bed adsorber (SBA) tests demonstrated that the mass transport kinetics for both ions are adequately rapid to permit simultaneous removal using HIX media in a fixed bed reactor.

Kinetic energy distributions of ions after surface collisions

International Nuclear Information System (INIS)

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

1991-01-01

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

Immobilisation of ion exchange resins in cement

International Nuclear Information System (INIS)

Howard, C.G.; Jolliffe, C.B.; Lee, D.J.

1990-02-01

Over the last seven years, Low Oxidation State Metal Ion reagents (LOMI) have been used to decontaminate the 100 MW(e) Steam Generating Heavy Water Ractor (SGHWR) at Winfrith. The use of these reagents has resulted in a dilute ionic solution containing activation products which are produced by corrosion of metallic components in the reactor. It has been demonstrated that the amount of activity in the solution can be reduced using organic ion exchanger resins. These resins consist of a cross linked polystyrene with sulphonic acid or quaternary ammonium function groups and can be successfully immobilised in blended cement systems. The formulation which has been developed is produced from a 9 to 1 blend of ground granulated blast furnace slag (BFS) and ordinary Portland cement (OPC) containing 28% ion exchange resin in the water saturated form. If 6% Microsilica is added to the blended cement the waste loading can be increased to 36 w/o. (author)

Organic and inorganic ion exchangers as catalysts for the heterogeneous alkylation of aromatics

Energy Technology Data Exchange (ETDEWEB)

Klein, J; Widdecke, H [Technische Univ. Braunschweig (Germany, F.R.). Inst. fuer Chemische Technologie

1979-06-01

Ion exchangers have advantages over low molecular for use in industrial alkylation reactions. The reactivity and selectivity behaviour of the polymeric catalysts was found to be markedly influenced by the structure of the polymeric matrix as well as the type and number of the functional groups. In this connection many similarities between inorganic ion exchangers (zeolites) and organic ion exchange resins were detected.

Application of radioactive tracers in upgradation of industrial grade ion exchange resin (Amberlite IRA-400)

International Nuclear Information System (INIS)

Lokhande, R.S.; Singare, P.U.

1998-01-01

The exchange rates of ion exchange are determined by application of 131 I as a tracer isotope. The exchange study carried out in this investigation deals with understanding the effectiveness of ion exchange resin (in iodide form) Amberlite IRA-400 at different concentrations of potassium iodide solution (electrolyte) with temperature of solution varying from 27-48 degC by keeping amount of ion exchange resin constant (1.0 g). The exchange study is also carried out by varying amount of ion exchange resins, for fixed temperature (27.0 degC) and for fixed concentration of potassium iodide solution (0.005 M). (author)

Isotope exchange reaction in uranous-uranyl-sulphuric acid system

International Nuclear Information System (INIS)

Ling Daren; Yue Tingsheng; Mu Dehai; Wang Yani

1990-01-01

The kinetics of the isotope exchange reaction between U(IV) and U(VI) has been studied in low concentrations of sulphuric acid. A minimum exchange rate appears at 0.25 M H 2 SO 4 . From the rates at different temperatures ranging from 20deg to 35deg C, an apparent activation energy of 86 kcal/mole was calculated. The exchange rate was found to be accelerated by the addition of ferrous ions, and a half-life of less than 1 s, was obtained. Probable mechanisms for the acceleration of the uranium isotope exchange reactions by acidity and ferrous ions are proposed. (orig.)

Study on rare earths complexes separation by means of different type of ion exchangers

International Nuclear Information System (INIS)

Hubicka, H.

1990-01-01

The applicability of different types of ion exchangers for purification and separation of rare earths complexes has been examined. The experimental work has been carried out on 14 chelating ion exchangers. The investigation results proved the great usefulness chelating ion exchangers especially of amino acid and phosphorus-type. Application of that type ion exchangers in column chromatographic process gave the excellent rare earths separation as well as enabled to obtain their preparates of high purity. 218 refs, 21 figs, 27 tabs

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

Science.gov (United States)

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

2014-01-01

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.

The effect of organic ion-exchange resin on properties of heterogeneous ion-exchange membranes

Czech Academy of Sciences Publication Activity Database

Křivčík, J.; Vladařová, J.; Hadrava, J.; Černín, A.; Brožová, Libuše

2010-01-01

Roč. 14, - (2010), s. 179-184 ISSN 1944-3994. [Membrane Science and Technology Conference of Visegrad Countries /4./ PERMEA 2009, 07.07.2009-11.07.2009] R&D Projects: GA MPO FT-TA4/116 Institutional research plan: CEZ:AV0Z40500505 Keywords : heterogeneous ion-exchange membrane * membrane modification * particle size of distribution Subject RIV: CG - Electrochemistry Impact factor: 0.752, year: 2010

Enhanced capacity and stability for the separation of cesium in electrically switched ion exchange

International Nuclear Information System (INIS)

Tawfic, A.F.; Dickson, S.E.; Kim, Y.; Mekky, W.

2015-01-01

Electrically switched ion exchange (ESIX) can be used to separate ionic contaminants from industrial wastewater, including that generated by the nuclear industry. The ESIX method involves sequential application of reduction and oxidation potentials to an ion exchange film to induce the respective loading and unloading of cesium. This technology is superior to conventional methods (e.g electrodialysis reversal or reverse osmosis) as it requires very little energy for ionic separation. In previous studies, ESIX films have demonstrated relatively low ion exchange capacities and limited film stabilities over repeated potential applications. In this study, the methodology for the deposition of electro-active films (nickel hexacyanoferrate) on nickel electrodes was modified to improve the ion exchange capacity for cesium removal using ESIX. Cyclic voltammetry was used to investigate the ion exchange capacity and stability. Scanning electron microscopy (SEM) was used to characterize the modified film surfaces. Additionally, the films were examined for the separation of cesium ions. This modified film preparation technique enhanced the ion exchange capacity and improves the film stability compared to previous methods for the deposition of ESIX films. (authors)

Enhanced capacity and stability for the separation of cesium in electrically switched ion exchange

Energy Technology Data Exchange (ETDEWEB)

Tawfic, A.F.; Dickson, S.E.; Kim, Y. [McMaster University, Hamilton, ON (Canada); Mekky, W. [AMEC NSS, Power and Process America, Toronto (Canada)

2015-03-15

Electrically switched ion exchange (ESIX) can be used to separate ionic contaminants from industrial wastewater, including that generated by the nuclear industry. The ESIX method involves sequential application of reduction and oxidation potentials to an ion exchange film to induce the respective loading and unloading of cesium. This technology is superior to conventional methods (e.g electrodialysis reversal or reverse osmosis) as it requires very little energy for ionic separation. In previous studies, ESIX films have demonstrated relatively low ion exchange capacities and limited film stabilities over repeated potential applications. In this study, the methodology for the deposition of electro-active films (nickel hexacyanoferrate) on nickel electrodes was modified to improve the ion exchange capacity for cesium removal using ESIX. Cyclic voltammetry was used to investigate the ion exchange capacity and stability. Scanning electron microscopy (SEM) was used to characterize the modified film surfaces. Additionally, the films were examined for the separation of cesium ions. This modified film preparation technique enhanced the ion exchange capacity and improves the film stability compared to previous methods for the deposition of ESIX films. (authors)

Kinetics of ion/molecule reactions in Xe++acteone system

International Nuclear Information System (INIS)

Vinogradov, P.S.; Misharin, A.S.

2002-01-01

A reaction of Xe+ ion with acetone and subsequent transformations of the product ions at a buffer gas pressure (He) of 1.1 Torr were studied by the flow reactor technique mass spectrometry. A kinetic scheme describing the evolution of the ionic composition has been determined. The rate constants of the key reactions involved in the scheme have been evaluated. A channel of the production of acetone cation in A state in a charge transfer reaction was observed. A production of slowly reacting isomer of the acetone cation in secondary reactions was detected. Its product in the reaction with acetone is the 'nonprotonated dimer'. The kinetics of the production of ternary ions - ( CH 3 CO + CH 3 COCH 3 )(m/e=101), CH 3 COCH 3 H + (m/e=59) as well as the production of ions of the fourth generation ( CH 3 CO + (CH 3 COCH 3 ) 2 ) (m/e=159) and (CH 3 COCH 3 ) 2 H + was observed. CH 3 CO + ion (m/e=43) was found as the main reaction product. The main pathways scheme of ionic transformations is shown. (nevyjel)

Transition from the constant ion mobility regime to the ion-atom charge-exchange regime for bounded collisional plasmas

International Nuclear Information System (INIS)

Poggie, Jonathan; Sternberg, Natalia

2005-01-01

A numerical and analytical study of a planar, collisional, direct-current, plasma-wall problem is presented. The fluid model for the problem is first validated by comparing numerical solutions with experimental data for low-pressure (∼0.1 Pa) electrode sheaths with wall potentials on the order of -100 V. For electric potential, ion number density, and ion velocity, good agreement was found between theory and experiment from within the sheath out to the bulk plasma. The frictional drag resulting from ion-neutral collisions is described by a model incorporating both linear and quadratic velocity terms. In order to study the transition from the constant ion mobility regime (linear friction) to the ion-atom charge-exchange collision regime (quadratic friction), the theoretical model was examined numerically for a range of ion temperatures and ion-neutral collision rates. It was found that the solution profiles in the quasineutral plasma depend on the ion temperature. For low ion temperatures they are governed mainly by the ion-atom charge-exchange regime, whereas for high temperatures they are governed by the constant ion mobility regime. Quasineutral plasma models corresponding to these two limiting cases were solved analytically. In particular, an analytical plasma solution is given for the ion-atom charge exchange regime that includes the effects of ion inertia. In contrast to the quasineutral plasma, the sheath is always governed for low to moderate collision rates by the ion-atom charge-exchange regime, independent of the ion temperature. Varying the collision rate, it was shown that when the wall potential is sufficiently high, the sheath cannot be considered collisionless, even if the collision rate is quite small

Influence of differences in resin-matrix structure on ion-exchange adsorption of trace amounts of Ag(I), Co(II) and Cr(III)

International Nuclear Information System (INIS)

Matsuzuru, Hideo; Wadachi, Yoshiki

1975-01-01

The influence of differences in resin-matrix structure on the ion-exchange adsorption of trace amounts of Ag(I), Co(II) and Cr(III) was studied by using both macroreticular and gel-type resins. The results indicate that the rate-determining step of the exchange mechanism of these ions is film diffusion under conditions of finite volume and at an ionic strengh of 1x10 -4 . The diffusion coefficient decreases with increasing size of the hydrated ions - in the order Dsub(Ag)>Dsub(Co)>Dsub(Cr). It may be said that the faster rate of exchange in the macroreticular resin is due to the larger surface area and pore size of this resin. Also, in a column system - as opposed to batch operation, it is assumed that the rate-determining step of the exchange reaction is film diffusion. With both resins, the kinetic coefficient β decreases in the order: βsub(Ag)>βsub(Co)>βsub(Cr). For the same linear velocity, a higher β-value is obtained with the macroreticular than with the gel-type resin. Consequently, a higher separating efficiency may be expected from the macroreticular resin for concentrating and separating trace amounts of cations from aqueous solution. (auth.)

Ion-exchange equilibrium of Fe3+-Cl- and UO22+-Cl- systems in a porous anion exchanger

International Nuclear Information System (INIS)

Takeda, Kunihiko; Kawakami, Fumiaki; Sasaki, Mitsunaga

1985-01-01

The ion-exchange equilibrium behavior of complex ions was investigatided in the systems of UO 2 2+ - Cl - and Fe 3+ - Cl - using an anion exchanger. It was performed by examining the dependency of adsorption distribution and selectivity of complexes on the micro structure of ion-exchangers, and temperature-dependency of selectivity. Changes in micropore structure of the ion-exchanger were found to have a significant effect on selectivity; the coefficient of selectivity and the average valence of the adsorbed species increased as the discrete pore ratio used as the index for pore structure decreased. In this study, equilibrium reactions were regarded as a sort of addition reaction for a easier analysis. This analysis based on the concept of addition chemical potential suggested that decreases in the discrete pore ratio were advantageous for the adsorption of complex ion species with higher valence, and average valence of the adsorbed species within the exchanger was shifted to the higher side. For this reason, it is assumed that the coefficient of selectivity became larger with a decrease in the discrete pore ratio. There is also a marked change in the coefficient of selectivity with temperature, and this becomes greater the higher the temperature. The ΔH of the present system accompanying the complex forming reaction is estimated to be 7 to 8 kcal/mol, and this value suggests that the temperature effect of the complex forming reaction contributes greatly to the change in selectivity with temperature. (author)

Ion exchange purification of scandium

Science.gov (United States)

Herchenroeder, Laurie A.; Burkholder, Harvey R.

1990-10-23

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

CFD Modeling of Flow and Ion Exchange Kinetics in a Rotating Bed Reactor System

DEFF Research Database (Denmark)

Larsson, Hilde Kristina; Schjøtt Andersen, Patrick Alexander; Byström, Emil

2017-01-01

A rotating bed reactor (RBR) has been modeled using computational fluid dynamics (CFD). The flow pattern in the RBR was investigated and the flow through the porous material in it was quantified. A simplified geometry representing the more complex RBR geometry was introduced and the simplified...... model was able to reproduce the main characteristics of the flow. Alternating reactor shapes were investigated, and it was concluded that the use of baffles has a very large impact on the flows through the porous material. The simulations suggested, therefore, that even faster reaction rates could...... be achieved by making the baffles deeper. Two-phase simulations were performed, which managed to reproduce the deflection of the gas–liquid interface in an unbaffled system. A chemical reaction was implemented in the model, describing the ion-exchange phenomena in the porous material using four different...

Saturation mechanism of decaying ion temperature gradient driven turbulence with kinetic electrons

International Nuclear Information System (INIS)

Idomura, Yasuhiro

2016-01-01

We present full-f gyrokinetic simulations of the ion temperature gradient driven (ITG) turbulence including kinetic electrons. By comparing decaying ITG turbulence simulations with adiabatic and kinetic electron models, an impact of kinetic electrons on the ITG turbulence is investigated. It is found that significant electron transport occurs even in the ITG turbulence, and both ion and electron temperature profiles are relaxed. In steady states, both cases show upshifts of nonlinear critical ion temperature gradients from linear ones, while their saturation mechanisms are qualitatively different. In the adiabatic electron case, the ITG mode is stabilized by turbulence driven zonal flows. On the other hand, in the kinetic electron case, passing electrons transport shows fine resonant structures at mode rational surfaces, which generate corrugated density profiles. Such corrugated density profiles lead to fine radial electric fields following the neoclassical force balance relation. The resulting E × B shearing rate greatly exceeds the linear growth rate of the ITG mode. (author)

Sorption-spectroscopic and test methods for the determination of metal ions on the solid-phase of ion-exchange materials

International Nuclear Information System (INIS)

Savvin, Sergey B; Dedkova, Valentina P; Shvoeva, Ol'ga P

2000-01-01

Data on sorption-spectroscopic and test methods for the determination of metal ions on the solid-phase of ion-exchange materials published over the past decade are reviewed. The advantages and disadvantages of ion-exchange materials are discussed. The detection limits and selectivity of these techniques are described. The bibliography includes 151 references.

Characteristics of floc formation of anion and cation exchange resin in precoat filter using powdered ion exchange resin

International Nuclear Information System (INIS)

Adachi, Tetsurou; Sawa, Toshio; Shindoh, Toshikazu.

1989-01-01

The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of floc formation. The physical, chemical and electrochemical properties of powdered ion exchange resin were measured and the factors related to floc formation of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index. It was found that these factors were mixing ratio, nature of resins and particle size of resins. In addition, it was assumed on the bases of these results that the amount of resin floc was related to sum of the surface electric charges of both resins. The filling ratio of resin floc was related to their product by multiplication and an experimental expression was obtained. The specific settle volume of resin floc could then be simulated by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author)

Characteristics of floc formation of anion and cation exchange resin in precoat filter using powdered ion exchange resin

Energy Technology Data Exchange (ETDEWEB)

Adachi, Tetsurou (Nitto Denko Corp., Ibaraki, Osaka (Japan)); Sawa, Toshio; Shindoh, Toshikazu

1989-09-01

The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of floc formation. The physical, chemical and electrochemical properties of powdered ion exchange resin were measured and the factors related to floc formation of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index. It was found that these factors were mixing ratio, nature of resins and particle size of resins. In addition, it was assumed on the bases of these results that the amount of resin floc was related to sum of the surface electric charges of both resins. The filling ratio of resin floc was related to their product by multiplication and an experimental expression was obtained. The specific settle volume of resin floc could then be simulated by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author).

Sol - gel inorganic ion exchangers for conditioning of medium level radioactive waste

International Nuclear Information System (INIS)

Arcangeli, G.; Traverso, D.M.; Gerontopoulos, P.; Fava, R.

1988-01-01

Decontamination of high-level liquid wastes and medium activity wastes streams by inorganic ion exchange combined with the conversion of the spent inorganic ion exchange material to waste ceramics presents a considerable potential for utilisation in waste conditioning. Ceramic waste forms are found superior to other candidate waste immobilisation forms but practical implementation is hampered because of the complexity of the related fabrication technology. This report shows the possibility of improving this situation by resorting to sol gel techniques earlier developed for preparation of nuclear fuel ceramics. The principal findings are: - superior quality ion exchange xerogel titanates in the form of mechanically resistant, size controlled microspheres can be prepared using a simple sol-gel technique; - the titanate particles can be also used as precursors in Evaporative Deposition on Xerogel Particles (EDXP) a new waste solidification process based on physical impregnation of the xerogel material with the waste liquid followed by evaporation; - waste loaded ion exchange microspheres can be converted to leach resistant ceramics by firing and/or cold pressing and sintering at 900 0 -1100 0 C; - sol-gel inorganic ion exchange and EDXP may find useful application in conditioning MAW streams. 44 figs., 43 refs

Ion-exchange properties of microporous tungstates: novel adsorbents for nuclear waste management applications

International Nuclear Information System (INIS)

Griffith, C.S.; Luca, V.; Eddowes, R.C.; Keegan, E.A.; Scales, N.

2003-01-01

A hydrothermally prepared tungsten oxide-based phase, ATS-1 (ANSTO Tungstate Sorbent), of nominal composition, Na 0.3 Mo 0.1 W 0.9O3 .χH 2 O, has been shown to display promising selectivity for both Cs + and Sr 2+ cations from acidic simulant, indicative of the Intermediate Level Liquid Waste (ILLW) produced from 99 Mo radioisotope production at the ANSTO site. The development of an inorganic ion-exchanger that displays such selectivity for both Cs + and Sr 2+ in acidic solutions has previously eluded researchers in the field of inorganic ion-exchangers. The ATS-1 adsorbent also displays exquisite selectivity for lead (and polonium) in low to high acidity solutions, and as such is being further investigated as a method to reduce the radiological hazard from 210 Pb and 210 Po during the processing of uranium ore bodies. The adsorption of Cs + , Sr 2+ and Pb 2+ cations by ATS-1 has been extensively investigated with respect to the kinetics of adsorption, capacity and the effect of competing cations viz. Na + , K + . The ATS-1 adsorbent has also been successfully granulated with an inert, organic matrix, which has consequently allowed the study of cation adsorption using more application-based, column separations. The results of these investigations suggest that these materials have potential application in several nuclear waste management issues in Australia at the present

Bituminous solidification, disposal, transport and burial of spent ion-exchange resins. Part of a coordinated programme on treatment of spent ion exchange resins

International Nuclear Information System (INIS)

Mozes, G.; Kristof, M.

1983-07-01

The project dealing with the incorporation of spent ion-exchange resins into bitumen was performed within the Agency coordinated research programme on treatment of spent ion-exchange resins. Physical and chemical properties of commercial ion-exchange resins, bitumens and bituminized resins were studied. It was shown that bitumen with low oil content and with a softening point of 60-70 deg. C are applicable for the incorporation of resins. The final waste form is allowed to contain maximum 50% resin. The comprehensive study of the biological resistance of B-30 bitumen was performed. That showed that any bacteriological attack can be regarded as generally insignificant. A continuously operating technology was realized on a semi-plant scale. The best operating conditions of this technology were determined. On the basis of the experience gained from the experiments a design of the bituminization plant of 50m 3 dry resin/year treatment capacity was proposed

Bench-Scale Studies with Argentine Ion Exchange Material

International Nuclear Information System (INIS)

Cicero-Herman, C.A.

2002-01-01

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

Rapid ion-exchange separations of actinides

International Nuclear Information System (INIS)

Usuda, Shigekazu

1988-01-01

For the purpose of studying short-lived actinide nuclides, three methods for rapid ion exchange separation of actinide elements with mineral acid-alcohol mixed media were developed: anion exchange with nitric acid-methyl alcohol mixed media to separate the transplutonium and rare earth elements from target material, U or Pu and Al catcher foils; anion exchange with hydrochloric acid-methyl alcohol media to separate Am+Cm, Bk and Cf+Fm from the target, catcher foils and major fission products; and cation exchange with hydrochloric acid-methyl alcohol media and with concentrated hydrochloric acid to separate the transplutonium elements as a group from the rare earths after eliminating the large amounts of U, Al, Cu, Fe etc. The methods enable one to perform rapid and effective separation at elevated temperature (90 deg C) and immediate source preparation for alpha-ray spectrometry. (author) 47 refs.; 10 figs

Analysis of Ion-Exchange Resin Capability of the RSG-GAS Demineralized Water System (GCA01)

International Nuclear Information System (INIS)

Diyah Erlina Lestari; Setyo Budi Utomo; Harsono

2012-01-01

The Demineralized water system (GCA01) is a system which is function to process raw water to be demineralized water using ion exchange resin unit consisting of a column of cation exchange resins, anion exchange resin column and the column resin mix bed. After certain time the ion exchange resins to be saturated so that is needed regeneration. The RSG-GAS demineralized water system (GCA01) not operated continuously and indication of when does an ion exchange resin regeneration on The RSG-GAS demineralized water system (GCA01) is the water conductivity from anion exchange resin column output indicates ≥ 5μS/cm. Analysis of capability of the ion exchange resin demineralized water system (GCA01) line I has been performed. The analysis was done by comparing the time required in the system operating cycle of regeneration to the next regeneration during the period 2011 and 2012. From the results of the analysis showed the cycle regeneration time is varies. This shows that ion exchange resin capability of the RSG-GAS demineralized water system (GCA01) is varies depending on the raw water quality and success of the regeneration ion exchange resin. (author)

The Quantitative Ion Exchange Separation of Uranium from Impurities

National Research Council Canada - National Science Library

Narayanan, Usha

1995-01-01

.... This procedure involve adsorption of uranium onto Bio-Rad AG 1X8 or MP-1 ion exchange resins in 8 M HCl, separation of uncomplexed or weakly complexed matrix ions with an 8 M HCl wash, and subsequent...

Kinetics of interaction from low-energy-ion bombardment of surfaces

International Nuclear Information System (INIS)

Horton, C.C.

1988-01-01

The kinetics of interaction from low energy oxygen ion bombardment of carbon and Teflon surfaces have been investigated. The surfaces were bombarded with 4.5 to 93 eV oxygen ions and emitted species were observed with a mass spectrometer. To obtain the kinetic information, the ion beam was square pulse modulated and reaction products were observed as a function of time. The kinetic information is contained in the response of the emitted species to the pulsed ion beam. Oxygen bombardment of carbon produced CO in three parallel branches with each following an adsorption-desorption process. The fast branch, with a rate constants of 12,000/sec, appeared to be sputter induced an was absent below about 19 eV. The medium and slow branches, with rate constants of 850/sec and 45/sec respectively, has little energy dependence and appeared to be due to chemical sputtering from two sites. The ratio of the fraction of the medium branch to that of the slow was constant at 1:3. The bombardment of Teflon produced CF in two parallel branches, with one following a series process and the other an adsorb-desorb process. The rate constant of the other branch were 22,000/sec and 7,000/sec and the rate constant of the other branch was 90/sec. The total signal fell monotonically with decreasing ion energy with the fraction for each branch holding constant at 71% for the series and 29% for the adsorb-desorb

Kinetics of electrophilic substitution of neodymium(III) by ytterbium(III) in aqueous solutions of ethylenediamintetraacetate and cyclohexanediaminetetraacetate

International Nuclear Information System (INIS)

Nikitenko, S.I.; Martynenko, L.I.; Pechurova, N.I.; Spitsyn, V.I.

1982-01-01

The kinetics of electrophilic substitution in systems containing rare earth element ions (REE) and Komplexon [tetrasodium ethylenediaminetetraacetate] have been studied little. At the same time, information about the mechanism of exchange is not only of theoretical interest but is important for the optimization of processes for separating and purifying REE. Least studied of all has been the mutual exchange in Komplexonate ions of light and heavy REE, although it is precisely the kinetics of exchange of different kinds of REE ions that primarily determines the effectiveness of the separation of their mixtures. We have studied electrophilic substitution in the case of the replacement of neodymium(III) by ytterbium(III) in solutions containing NdL - and Yb 3 + , where L 4 - and D 4 -

Mixed matrix microporous hollow fibers with ion-exchange functionality

NARCIS (Netherlands)

Kiyono, R.; Kiyono, R.; Koops, G.H.; Wessling, Matthias; Strathmann, H.

2004-01-01

Heterogeneous hollow fiber membranes with cation exchange functionality are prepared using a wet spinning technique. The spinning dope solutions are prepared by dispersing finely ground cation ion-exchange resin (CER) particles in an N-methyl pyrrolidone solution of polysulfone (PSF). The polymer

Ra/Ca separation by ion exchange chromatography

International Nuclear Information System (INIS)

Flores Mendoza, J.

1990-01-01

Ra/Ca separation by ion exchange. The objective of this work was to acquire knowledge of the chromatographic behaviour of the alkaline earth cations calcium, barium and radium and the obtention of well-defined alpha spectra of 226 Ra. Three cationic ion exchange resins (Dower 50 W-X8, AG 50W-XB and Merck I) and three complexing agents (ethylenediaminetetraacetic acid, citric acid and tartaric acid) at various pH values have been investigated. The three types of ions are fixed on the resins at pH 4.8; calcium is eluted at pH between 5 and 6 depending on the resin; barium and radium are eluted at pH values from 8 to 11. Radium is also eluted with a 2 M nitric acid solution, from which it can be electrodeposited on a stainless steel disk potassium fluoride as electrolyte at pH 14. The electrolysis is conducted for 18 hours with a current of mA. Under these conditions high resolution alpha spectra were obtained for 226 Ra, which was practically free from radioactive contaminants (Author)

Evidence for Sequence Scrambling and Divergent H/D Exchange Reactions of Doubly-Charged Isobaric b-Type Fragment Ions

Science.gov (United States)

Zekavat, Behrooz; Miladi, Mahsan; Al-Fdeilat, Abdullah H.; Somogyi, Arpad; Solouki, Touradj

2014-02-01

To date, only a limited number of reports are available on structural variants of multiply-charged b-fragment ions. We report on observed bimodal gas-phase hydrogen/deuterium exchange (HDX) reaction kinetics and patterns for substance P b10 2+ that point to presence of isomeric structures. We also compare HDX reactions, post-ion mobility/collision-induced dissociation (post-IM/CID), and sustained off-resonance irradiation-collision induced dissociation (SORI-CID) of substance P b10 2+ and a cyclic peptide with an identical amino acid (AA) sequence order to substance P b10. The observed HDX patterns and reaction kinetics and SORI-CID pattern for the doubly charged head-to-tail cyclized peptide were different from either of the presumed isomers of substance P b10 2+, suggesting that b10 2+ may not exist exclusively as a head-to-tail cyclized structure. Ultra-high mass measurement accuracy was used to assign identities of the observed SORI-CID fragment ions of substance P b10 2+; over 30 % of the observed SORI-CID fragment ions from substance P b10 2+ had rearranged (scrambled) AA sequences. Moreover, post-IM/CID experiments revealed the presence of two conformer types for substance P b10 2+, whereas only one conformer type was observed for the head-to-tail cyclized peptide. We also show that AA sequence scrambling from CID of doubly-charged b-fragment ions is not unique to substance P b10 2+.

Evidence for sequence scrambling and divergent H/D exchange reactions of doubly-charged isobaric b-type fragment ions.

Science.gov (United States)

Zekavat, Behrooz; Miladi, Mahsan; Al-Fdeilat, Abdullah H; Somogyi, Arpad; Solouki, Touradj

2014-02-01

To date, only a limited number of reports are available on structural variants of multiply-charged b-fragment ions. We report on observed bimodal gas-phase hydrogen/deuterium exchange (HDX) reaction kinetics and patterns for substance P b10(2+) that point to presence of isomeric structures. We also compare HDX reactions, post-ion mobility/collision-induced dissociation (post-IM/CID), and sustained off-resonance irradiation-collision induced dissociation (SORI-CID) of substance P b10(2+) and a cyclic peptide with an identical amino acid (AA) sequence order to substance P b10. The observed HDX patterns and reaction kinetics and SORI-CID pattern for the doubly charged head-to-tail cyclized peptide were different from either of the presumed isomers of substance P b10(2+), suggesting that b10(2+) may not exist exclusively as a head-to-tail cyclized structure. Ultra-high mass measurement accuracy was used to assign identities of the observed SORI-CID fragment ions of substance P b10(2+); over 30% of the observed SORI-CID fragment ions from substance P b10(2+) had rearranged (scrambled) AA sequences. Moreover, post-IM/CID experiments revealed the presence of two conformer types for substance P b10(2+), whereas only one conformer type was observed for the head-to-tail cyclized peptide. We also show that AA sequence scrambling from CID of doubly-charged b-fragment ions is not unique to substance P b10(2+).

Livestock wastewater treatment by zeolite ion exchange and gamma-ray irradiation

International Nuclear Information System (INIS)

Lee, Sang Ryul; Kim, Tak Hyun; Lee, Myun Joo

2008-01-01

Livestock wastewater containing high concentrations of organic matters and ammonia-nitrogen has been known as one of the recalcitrant wastewater. It is difficult to treat by conventional wastewater treatment techniques. This study was carried out to evaluate the feasibility of zeolite ion exchange and gamma-ray irradiation treatment of livestock wastewater. The removal efficiencies of SCOD Cr and NH3-N were significantly enhanced by gamma-ray irradiation after zeolite ion exchange as a pre-treatment. However, the effects of zeolite particle size on the SCOD Cr and NH 3 -N removal efficiencies were insignificant. These results indicate that the combined process of zeolite ion exchange and gamma-ray irradiation has potential for the treatment of livestock wastewater

Kinetics of H-D exchange in olefins with complicating reactions

International Nuclear Information System (INIS)

Trokhimets, A.I.

1979-01-01

The kinetics of H-D-exchange is considered for olefins under conditions when simple and complicated exchange occur together with hydrogenation. If hydrogenation takes place in the system, it is theoretically impossible to derive the integrated rate equation for the accumulation of deuterium in the olefin. The variation of the concentration of different deuteroolefins during the process can be calculated numerically. A method is proposed for evaluating the contribution of individual steps to the overall process and determining the rate constants of the most important reactions. (author)

Radiation deterioration of ion-exchange Nafion N117CS membranes

International Nuclear Information System (INIS)

Iwai, Yasunori; Hiroki, Akihiro; Tamada, Masao; Isobe, Kanetsugu; Yamanishi, Toshihiko

2010-01-01

The cation-exchange Nafion N117 membranes swelling in electrolyte solution were irradiated with γ-rays or electron beams at various doses up to 1500 kGy in the temperature range from room temperature to 343 K to obtain detailed information on the effect of ion-exchange on the radiation deterioration in mechanical properties and ion-exchange capacity. Considerable deterioration in mechanical properties was observed when the Nafion membranes swelling in electrolyte solution were irradiated. A reason is the promotion of degradation with oxygen molecules produced by the irradiation of electrolyte solution. The concentration of electrolyte solution influenced strongly the radiation deterioration in mechanical properties. Keeping the concentration of metal ions to be negligible is important when electrolyzed highly radioactive solution in the light of the durability of polyperfluorosulfonic acid (PFSA) membrane. A sort of cation in electrolyte solution negligibly influenced radiation deterioration in mechanical properties. A sort of anion in electrolyte solution had negligible effect on radiation deterioration in mechanical properties and ion-exchange capacity. The discrepancy in the radiation deterioration in mechanical properties of Nafion membranes swelling in NaCl solution was observed between the specimens irradiated with γ-rays and electron beams. This discrepancy can be explained from the low diffusivity of oxygen from bulk into the membrane.

Field experiment on multicomponent ion exchange in a sandy aquifer

International Nuclear Information System (INIS)

Bjerg, P.L.; Christensen, T.H.

1990-01-01

A field experiment is performed in a sandy aquifer in order to study ion exchange processes and multicomponent solute transport modeling. An injection of groundwater spiked with sodium and potassium chloride was performed over a continuous period of 37 days. The plume is monitored by sampling 350 filters in a spatial grid. The sampling aims at establishing compound (calcium, magnesium, potassium, sodium, chloride) breakthrough curves at various filters 15 to 100 m from the point of injection and areal distribution maps at various cross sections from 0 to 200 m from the point of injection. A three-dimensional multicomponent solute transport model will be used to model the field experiments. The chemical model includes cation exchange, precipitation, dissolution, complexation, ionic strength and the carbonate system. Preliminary results from plume monitoring show that the plume migration is relatively well controlled considering the scale and conditions of the experiment. The transverse dispersion is small causing less dilution than expected. The ion exchange processes have an important influence on the plume composition. Retardation of the injected ions is substantial, especially for potassium. Calcium exhibits a substantial peak following chloride due to release from the ion exchange sites on the sediment. (Author) (8 refs., 5 figs., tab.)

Ion exchange of natural natrolite in melted salts

International Nuclear Information System (INIS)

Faghihian, H.; Nekuei, P.

2007-01-01

In this research the ion exchange potential of natrolite towards K + , TI + , Cs +2 , Ca +2 , Ni +2 , Cu 2+ , and Co 2+ in their melted salts was investigated. The effect of temperature, reaction time and zeolite to salt ratio on the exchange relation was studied. The exchange of ca 2+ , Ni 2+ , cu 2+ , and Co 2+ was negligible and was equal to 2.59, 6.29, 3.14 and 5.04 percent respectively whereas the exchange of K + , Tl + , Cs + was relatively high and equal to 82.36,66.67 and 42.98 percent respectively

Binding kinetics of magnetic nanoparticles on latex beads and yeast cells studied by magnetorelaxometry

International Nuclear Information System (INIS)

Eberbeck, Dietmar; Bergemann, Christian; Hartwig, Stefan; Steinhoff, Uwe; Trahms, Lutz

2005-01-01

The ion exchange mediated binding of magnetic nanoparticles (MNP) to modified latex spheres and yeast cells was quantified using magnetorelaxometry. By fitting subsequently recorded relaxation curves, the kinetics of the binding reactions was extracted. The signal of MNP with weak ion exchanger groups bound to latex and yeast cells scales linearly with the concentration of latex beads or yeast cells whereas that of MNP with strong ion exchanger groups is proportional to the square root of concentration. The binding of the latter leads to a much stronger aggregation of yeast cells than the former MNP

Studies on the ion-exchange behavior of chromium ferrocyanide

Energy Technology Data Exchange (ETDEWEB)

Malik, W U; Srivastava, S K; Singh, Raj Pal; Kumar, Satish [Roorkee Univ. (India). Dept. of Chemistry

1977-01-01

The sorption of univalent, bivalent and trivalent ions has been studied on chromium ferrocyanide gel. The distribution of various metal cations were determined by shaking the exchanger (0.1 g) and 20 ml of 0.005M metal ion solution of pH 2-3, until equilibrium was attained. The concentration of Pb/sup 2 +/, Cu/sup 2 +/, Mn/sup 2 +/, Ni/sup 2 +/, Mg/sup 2 +/ and Al/sup 3 +/ were determined by EDTA, ZrO/sup 2 +/, Th/sup 4 +/, UO/sup 2 +/ and Fe/sup 2 +/ were estimated spectrophotometrically and radiometric methods were used for Rb/sup +/, Cs/sup +/, Tl/sup +/, Ag/sup +/, Zn/sup 2 +/, Co/sup 2 +/, Cd/sup 2 +/, Hg/sup 2 +/ and Fe/sup 3 +/ metal ions. The distribution coefficients of various univalent, bivalent and trivalent metal ions (0.002M) were also determined as a function of NH/sub 4/NO/sub 3/ and HNO/sub 3/ concentrations and pH. The studies reveal a high sorption capacity for Cs/sup +/, Tl/sup +/, Ag/sup +/, Cu/sup 2 +/, Zn/sup 2 +/, Cd/sup 2 +/, Fe/sup 3 +/ and Th/sup 4 +/. The sorption of monovalent cations show purely ion exchange mechanism while the uptake of bivalent and trivalent cations is non-equivalent in nature. Single elution of Rb/sup +/, Cs/sup +/ and Tl/sup +/ has been performed from the columns of this exchanger and the recovery is almost complete in all the cases. Cu/sup 2 +/ and Ag/sup +/ get completely adsorbed on the gel column and their elution is not possible probably due to the formation of some new solid phases. Depending on the Ksub(d) values of the metal ions, a large number of separations of radiochemical as well as analytical importance can be performed on the columns of this exchanger material. It is apparent from the Ksub(d) values that a number of separations as Hg/sup 2 +/ from Mg/sup 2 +/, Ca/sup 2 +/ and Pb/sup 2 +/; Mg/sup 2 +/ from Mn/sup 2 +/: Fe/sup 3 +/ from Al/sup 3 +/; and Th/sup 4 +/ from ZrO/sup 2 +/ can be performed on the columns of this exchanger.

Treatment of spent ion-exchange resins for storage and disposal

International Nuclear Information System (INIS)

1985-01-01

This report describes the experience gained by different countries on storage of spent ion exchange resins, immobilization of them into various matrices and the development of new methods in decomposition and solidification of spent resins. The report contains all the results of the Coordinated Research Programme together with additional data available from countries not participating in this programme. A review of practical industrial experience in treating spent ion exchange resins is given in the annex

Selective separation of radionuclides from nuclear waste solutions with inorganic ion exchangers

International Nuclear Information System (INIS)

Lehto, J.; Harjula, R.

1999-01-01

Nuclear industry produces and stores large volumes of radioactive waste solutions. Removal of radionuclides from the solutions is an important and challenging task for two main reasons: reductions in the volumes of solidified waste, which have to be disposed of, and reductions in the radioactive discharges into the environment. Since the radioactive elements in most waste solutions are in trace concentrations and the waste solutions contain large excesses of inactive metal ions, highly selective separation methods are needed for the removal of radionuclides. A number of inorganic ion exchange materials are very selective to key radionuclides and they can play an important role in solving these problems. The spectrum of nuclear waste solutions is rather wide considering their radionuclide contents, concentrations of interfering salts and acidity/alkalinity. Therefore, several inorganic ions exchangers are needed for the removal of most harmful radionuclides from a variety of solutions. This paper discusses the use and requirements of inorganic ion exchange materials in nuclear waste management. Special attention is paid to the novel ion exchange materials developed in the Laboratory of Radiochemistry, University of Helsinki. (orig.)

Some considerations on the treatment of the kinetic data of heterogeneous isotope exchange

International Nuclear Information System (INIS)

Koernyei, J.; Szirtes, L.; Lakatos, M.

1985-01-01

A direct curve simulation treatment was worked out for the evaluation of the kinetic curves of heterogeneous isotope exchange. Based on the data obtained by a personal computer, some considerations were made on the transport processes in the fully and half exchanged sodium forms of crystalline zirconium phosphate. (author)

Kinetic models for goods exchange in a multi-agent market

Science.gov (United States)

Brugna, Carlo; Toscani, Giuseppe

2018-06-01

In this paper we introduce a system of kinetic equations describing an exchange market consisting of two populations of agents (dealers and speculators) expressing the same preferences for two goods, but applying different strategies in their exchanges. Similarly to the model proposed in Toscani et al. (2013), we describe the trading of the goods by means of some fundamental rules in price theory, in particular by using Cobb-Douglas utility functions for the exchange. The strategy of the speculators is to recover maximal utility from the trade by suitably acting on the percentage of goods which are exchanged. This microscopic description leads to a system of linear Boltzmann-type equations for the probability distributions of the goods on the two populations, in which the post-interaction variables depend from the pre-interaction ones in terms of the mean quantities of the goods present in the market. In this case, it is shown analytically that the strategy of the speculators can drive the price of the two goods towards a zone in which there is a branded utility for their group. Also, according to Toscani et al. (2013), the general system of nonlinear kinetic equations of Boltzmann type for the probability distributions of the goods on the two populations is described in details. Numerical experiments then show how the policy of speculators can modify the final price of goods in this nonlinear setting.

Separation of uranium from sodium carbonate - sodium bicarbonate eluate by ion exchange method

International Nuclear Information System (INIS)

Sakane, Kohji; Hirotsu, Takahiro; Fujii, Ayako; Katoh, Shunsaku; Sugasaka, Kazuhiko

1982-01-01

The ion exchange method was used for separating uranium from the eluate (0.5 N Na 2 CO 3 -0.5 N NaHCO 3 ) that was obtained in the extraction process of uranium from natural sea water by using the titanium-activated carbon composite adsorbent. Uranium in the eluate containing 3 mg/1 uranium was adsorbed by ion exchange resin (Amberlite IRA-400), and was eluted with the eluant (5 % NaCl-0.5 % Na 2 CO 3 ). The concentration ratio of uranium in the final concentrated-eluate became more than 20 times. The eluting solution to the adsorbent and the eluant to the resin could be repeatedly used in the desorption-ion exchange process. Sodium carbonate was consumed at the desorption step, and sodium bicarbonate was consumed at the ion exchange step. The concentration ratio of uranium was found to decrease as chloride ion in the eluate increased. (author)

Separation of uranium from sodium carbonate-sodium bicarbonate eluate by ion exchange method

International Nuclear Information System (INIS)

Sakane, Kohji; Hirotsu, Takahiro; Fujii, Ayako; Katoh, Shunsaku; Sugasaka, Kazuhiko

1982-01-01

The ion exchange method was used for separating uranium from the eluate (0.5 N Na 2 CO 3 -0.5 N NaHCO 3 ) that was obtained in the extraction process of uranium from natural sea water by using the titanium-activated carbon composite adsorbent. Uranium in the eluate containing 3 mg/l uranium was adsorbed by ion exchange resin (Amberlite IRA-400), and was eluted with the eluent (5% NaCl-0.5% Na 2 CO 3 ). The concentration ratio of uranium in the final concentrated-eluate became more than 20 times. The eluting solution to the adsorbent and the eluant to the resin could be repeatedly used in the desorption-ion exchange process. Sodium carbonate was consumed at the desorption step, and sodium bicarbonate was consumed at the ion exchange step. The concentration ratio of uranium was found to decrease as chloride ion in the eluate increased. (author)

Effect of Landau damping on kinetic Alfven and ion-acoustic solitary waves in a magnetized nonthermal plasma with warm ions

International Nuclear Information System (INIS)

Bandyopadhyay, Anup; Das, K.P.

2002-01-01

The evolution equations describing both kinetic Alfven wave and ion-acoustic wave in a nonthermal magnetized plasma with warm ions including weak nonlinearity and weak dispersion with the effect of Landau damping have been derived. These equations reduce to two coupled equations constituting the KdV-ZK (Korteweg-de Vries-Zakharov-Kuznetsov) equation for both kinetic Alfven wave and ion-acoustic wave, including an extra term accounting for the effect of Landau damping. When the coefficient of the nonlinear term of the evolution equation for ion-acoustic wave vanishes, the nonlinear behavior of ion-acoustic wave, including the effect of Landau damping, is described by two coupled equations constituting the modified KdV-ZK (MKdV-ZK) equation, including an extra term accounting for the effect of Landau damping. It is found that there is no effect of Landau damping on the solitary structures of the kinetic Alfven wave. Both the macroscopic evolution equations for the ion-acoustic wave admits solitary wave solutions, the former having a sech 2 profile and the latter having a sech profile. In either case, it is found that the amplitude of the ion-acoustic solitary wave decreases slowly with time

Operating experience with ion exchanger beds in CIRUS

International Nuclear Information System (INIS)

Acharya, V.N.; Hajra, P.

1977-01-01

Operating experience with the ion exchanger beds in CIRUS reactor is narrated. Ion exchangers are provided for demineralisation of make up water and purification of closed loop water circuits. Exhaustion of resin is assessed on the basis of CO 2 concentration in the helium vent gas of the heavy water system. It is recommended that valves in the resin columns for rod handling bays be located outside the enclosure and each bed to reduce man-rem consumption during maintenance. Repeated backwash of the bed reduces chocking of water space with resin fines. Preventive maintenance avoids leakage past valves. Active resin from the resin beds is removed by hydraulic transfer method. (M.G.B.)

Glycerol acetals, kinetic study of the reaction between glycerol and formaldehyde

International Nuclear Information System (INIS)

Agirre, I.; Garcia, I.; Requies, J.; Barrio, V.L.; Gueemez, M.B.; Cambra, J.F.; Arias, P.L.

2011-01-01

The acetalization reaction between glycerol and formaldehyde using Amberlyst 47 acidic ion exchange resin was studied. These acetals can be obtained from renewable sources (bioalcohols and bioalcohol derived aldehydes) and seem to be good candidates for different applications such as oxygenated diesel additives. A preliminary kinetic study was performed in a batch stirred tank reactor studying the influence of different process parameters like temperature, feed composition and the stirring speed. A pseudo homogenous kinetic model able to explain the reaction mechanism was adjusted. Thus, the corresponding order of reaction was determined. Amberlyst 47 acidic ion exchange resin showed a fairly good behavior allowing 100% of selectivity towards acetals formation. However, the studied acetalization reaction showed high thermodynamic limitations achieving glycerol conversions around 50% using a stoichiometric feed ratio at 353 K. The product is a mixture of two isomers (1,3-Dioxan-5-ol and 1,3-dioxolane-4-methanol) and the conversion of 1,3-dioxolane-4-methanol into 1,3-Dioxan-5-ol was also observed. -- Highlights: → The reaction between glycerol and acetaldehyde shows thermodynamic limitations. → Amberlyst 47 ion exchange resins show 100% of selectivity. → A pseudo-homogeneous kinetic model is able to predict the reaction progress. → Isomerization reactions were observed from dioxalanes to dioxanes.

Calcium isotope fractionation in ion-exchange chromatography

International Nuclear Information System (INIS)

Russell, W.A.; Papanastassiou, D.A.

1978-01-01

Significant fractionation of the isotopes of calcium has been observed during elution through short ion-exchange columns packed with Dowex 50W-X8 resin. A double isotopic tracer was used to provide correction for instrumental fractionation effects. The absolute 40 Ca/ 44 Ca ratio is determined by this method to 0.05% and provides a measure of the fractionation of all Ca isotopes. It is found that the lighter isotopes are preferentially retained by the resin, with variations in 40 Ca/ 44 Ca between the first and last fractions of up to 1.1%. An estimate of the separation factor between batch solute and resin gives epsilon = 2.1 x 10 -4 . Details of the chemical or physical mechanisms causing isotope fractionation of Li, Na, Ca, and other elements during ion-exchange chromatography are not yet clear

New inorganic (an)ion exchangers based on Mg–Al hydrous oxides: (Alkoxide-free) sol–gel synthesis and characterisation

KAUST Repository

Chubar, Natalia

2011-01-01

New inorganic ion exchangers based on double Mg-Al hydrous oxides were generated via the new non-traditional sol-gel synthesis method which avoids using metal alkoxides as raw materials. Surface chemical and adsorptive properties of the final products were controlled by several ways of hydrogels and xerogels treatments which produced the materials of the layered structure, mixed hydrous oxides or amorphous adsorbents. The final adsorptive materials obtained via thermal treatment of xerogels were the layered mesoporous materials with carbonate in the interlayer space, surface abundance with hydroxylic groups and maximum adsorptive capacity to arsenate. Higher affinity of Mg-Al hydrous oxides towards H2AsO4- is confirmed by steep adsorption isotherms having plateau (removal capacity) at 220. mg[As]. gdw-1 for the best sample at pH = 7, fast adsorption kinetics and little pH effect. Adsorption of arsenite, fluoride, bromate, bromide, selenate, borate by Mg-Al hydrous oxides was few times high either competitive (depending on the anion) as compare with the conventional inorganic ion exchange adsorbents. © 2011 Elsevier Inc.

New inorganic (an)ion exchangers based on Mg–Al hydrous oxides: (Alkoxide-free) sol–gel synthesis and characterisation

KAUST Repository

Chubar, Natalia

2011-05-01

New inorganic ion exchangers based on double Mg-Al hydrous oxides were generated via the new non-traditional sol-gel synthesis method which avoids using metal alkoxides as raw materials. Surface chemical and adsorptive properties of the final products were controlled by several ways of hydrogels and xerogels treatments which produced the materials of the layered structure, mixed hydrous oxides or amorphous adsorbents. The final adsorptive materials obtained via thermal treatment of xerogels were the layered mesoporous materials with carbonate in the interlayer space, surface abundance with hydroxylic groups and maximum adsorptive capacity to arsenate. Higher affinity of Mg-Al hydrous oxides towards H2AsO4- is confirmed by steep adsorption isotherms having plateau (removal capacity) at 220. mg[As]. gdw-1 for the best sample at pH = 7, fast adsorption kinetics and little pH effect. Adsorption of arsenite, fluoride, bromate, bromide, selenate, borate by Mg-Al hydrous oxides was few times high either competitive (depending on the anion) as compare with the conventional inorganic ion exchange adsorbents. © 2011 Elsevier Inc.

Isolation of nitrosylruthenium nitrato complexes by ion exchange and extraction chromatography

International Nuclear Information System (INIS)

Huang, H.; Liu, L.

TBP Levextrel and cation exchange resins were used to separate RuNO nitrato complexes of different nitric acid concentrations. 7402 quaternary ammonium salt Levextrel was used instead of an anionic exchange resin to separate anionic and neutral complex ions. The results indicated that D 3 and D 4 , which can easily be extracted by TBP, were anionic and neutral complex ions

A novel electrochemical ion exchange system and its application in water treatment.

Science.gov (United States)

Li, Yansheng; Li, Yongbin; Liu, Zhigang; Wu, Tao; Tian, Ying

2011-06-01

A novel electrochemical ion exchange system with porous cylinder electrodes is proposed for treatment of wastewater. This system can be used for desalination without the costly ion-exchange membrane and extra chemical reagents. Since the electrodes are completely uniform and no ion-exchange membrane was used in this system, it can be operated by switching anodes and cathodes flexibly for eliminating the scaling on the surface of electrodes. The strong base ion-exchange resin grains placed among the anode and cathode have played as supporting electrolyte, which is capable for the treatment of wastewater with low conductivity. The concentrated and neutralized anolyte containing chlorine is effective for disinfection and contaminants removal. Under the experimental conditions, the removal percentage of total dissolved salts was 83% and the removal percentage of chemical oxygen demand was 92% without consumption of extra chemical reagents. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

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

International Nuclear Information System (INIS)

Smith, F.; Hamm, Luther; Aleman, Sebastian; Michael, Johnston

2008-01-01

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

Removal of strontium ions from solutions using granulated zeolites

International Nuclear Information System (INIS)

Bronic, J.; Subotic, B.

1992-01-01

The ion-exchange process on columns filled with granulated zeolites is determined by several physico-chemical parameters. The influence of these parameters (zeolite type, concentration of exchangeable ions in solution, temperature, flow rate, etc.) on the kinetics of ion-exchange process was studied by measuring the Sr 2+ ion concentration in solution before and after passing through a column filled with various granulated zeolites (zeolite 13X, zeolite A and synthetic mordenite). Using the experimental technique of radioactive labeling by 89 Sr, the distribution of Sr 2+ ions in column fillings were also determined. From the results obtained, the optimal conditions for the most efficient removal of strontium ions from solutions using granulated zeolites can be defined. (author) 24 refs.; 9 figs

Equilibrium isotope exchange kinetics of native and site-specific mutant forms of E. coli aspartate transcarbamoylase

International Nuclear Information System (INIS)

Wedler, F.C.; Hsuanyu, Y.; Kantrowitz, E.R.

1987-01-01

Isotope exchange kinetics at equilibrium (EIEK) have been used to probe the kinetic and regulatory mechanisms of native aspartate transcarbamoylase (ATCase) from E. coli at pH 7.0, 30 0 . Substrate saturation patterns were most consistent with a preferred order random kinetic mechanism: C-P prior to L-Asp, C-Asp released before Pi, with the Asp ↔ C-Asp exchange rate 5X faster than C-P ↔ Pi. Computer simulations allow one to fit the EIEK experimental data and to arrive at the best set of kinetic constants for a given enzyme state. These approaches have been applied to modified ATCase. Bound CTP and ATP were observed, respectively, to inhibit and activate differentially Asp ↔ C-Asp, but not C-P ↔ Pi, indicating that these modifiers alter the association-dissociation rates of L-Asp and C-Asp but not of C-P or Pi. Low levels of PALA activated both exchange rates (due to shifting the T-R equilibrium), but higher [PALA] completely blocked both exchanges. The effects of a site-specific mutation of Tyr240 Phe have been similarly probed by EIEK methods. The Phe240 mutant enzyme exhibited kinetic properties markedly different from native ATCase: the data indicate that Phe240 ATCase is much closer to an R-state enzyme than is native enzyme

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

Science.gov (United States)

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

2017-06-01

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

Use of water as displacing agent in ion exchange chromatographic separation of isotope of boron using weak base ion exchange resin

International Nuclear Information System (INIS)

Sharma, B.K.; Mohanakrishnan, G.; Anand Babu, C.; Krishna Prabhu, R.

2008-01-01

Experiments were undertaken to study the feasibility of using weakly basic anion exchange resin for enrichment of isotopes of boron by ion exchange chromatography and water as eluent. The results of experiments carried out to determine total chloride capacity (TCC), strong base capacity (SBC) of the resin at different concentrations of boric acid and enrichment profiles are reported in this paper. (author)

Phosphate recovery from wastewater using engineered superparamagnetic particles modified with layered double hydroxide ion exchangers.

Science.gov (United States)

Drenkova-Tuhtan, Asya; Mandel, Karl; Paulus, Anja; Meyer, Carsten; Hutter, Frank; Gellermann, Carsten; Sextl, Gerhard; Franzreb, Matthias; Steinmetz, Heidrun

2013-10-01

An innovative nanocomposite material is proposed for phosphate recovery from wastewater using magnetic assistance. Superparamagnetic microparticles modified with layered double hydroxide (LDH) ion exchangers of various compositions act as phosphate adsorbers. Magnetic separation and chemical regeneration of the particles allows their reuse, leading to the successful recovery of phosphate. Based upon the preliminary screening of different LDH ion exchanger modifications for phosphate selectivity and uptake capacity, MgFe-Zr LDH coated magnetic particles were chosen for further characterization and application. The adsorption kinetics of phosphate from municipal wastewater was studied in dependence with particle concentration, contact time and pH. Adsorption isotherms were then determined for the selected particle system. Recovery of phosphate and regeneration of the particles was examined via testing a variety of desorption solutions. Reusability of the particles was demonstrated for 15 adsorption/desorption cycles. Adsorption in the range of 75-97% was achieved in each cycle after 1 h contact time. Phosphate recovery and enrichment was possible through repetitive application of the desorption solution. Finally, a pilot scale experiment was carried out by treating 125 L of wastewater with the particles in five subsequent 25 L batches. Solid-liquid separation on this scale was carried out with a high-gradient magnetic filter (HGMF). Copyright © 2013 Elsevier Ltd. All rights reserved.

Determination of γ-hydroxybutyrate in human urine samples by ion exclusion and ion exchange two-dimensional chromatography system.

Science.gov (United States)

Liu, Junwei; Deng, Zhifen; Zhu, Zuoyi; Wang, Yong; Wang, Guoqing; Sun, Yu-An; Zhu, Yan

2017-12-15

A two-dimensional ion chromatography system was developed for the determination of γ-hydroxybutyrate (GHB) in human urine samples. Ion exclusion chromatography was used in the first dimensional separation for elimination of urine matrices and detection of GHB above 10mgL -1 , ion exchange chromatography was used in the second dimensional separation via column-switching technique for detection of GHB above 0.08mgL -1 . Under the optimized chromatographic conditions, the ion exclusion and ion exchange chromatography separation system exhibited satisfactory repeatability (RSDchromatography system was convenient and practical for the determination of GHB in human urine samples. Copyright © 2017 Elsevier B.V. All rights reserved.

High-performance ion-exchange chromatography of alkali metals with conductivity detection

International Nuclear Information System (INIS)

Ahmad, M.; Khan, A.R.

1981-01-01

High-performance ion-exchange chromatography of alkali metal and ammonium ions was studied using a conductivity meter as detector. Elution with 0.003 N mitric acid gave excellent resolution. Sensitivity levels, for a 200 micro litre injection, vary from 5 ppm for potassium to 0.1 ppm for lithium. A method to decrease retention times by reducing the exchange capacity of the cation exchange column used by loading it with calciumions, without affecting the resolation, has been described. Application of the method to water, soil and uranium dioxide samples has been demonstrated. (author)

New inorganic (an)ion exchangers with a higher affinity for arsenate and a competitive removal capacity towards fluoride, bromate, bromide, selenate, selenite, arsenite and borate

KAUST Repository

Chubar, Natalia

2011-12-01

Highly selective materials and effective technologies are needed to meet the increasingly stronger drinking water standards for targeted ionic species. Inorganic ion exchangers based on individual and mixed-metal hydrous oxides (or mixed adsorbents that contain inorganic ion exchangers in their composition) are adsorptive materials that are capable of lowering the concentrations of anionic contaminants, such as H 2AsO 4 -, H 3AsO 3, F -, Br -, BrO 3 -, HSeO 4 -, HSeO 3 - and H 3BO 3, to 10 μg/L or less. To achieve a higher selectivity towards arsenate, a new ion exchanger based on Mg-Al hydrous oxides was developed by a novel, cost-effective and environmentally friendly synthesis method via a non-traditional (alkoxide-free) sol-gel approach. The exceptional adsorptive capacity of the Mg-Al hydrous oxides towards H 2AsO 4 - (up to 200 mg[As]/gdw) is due to the high affinity of this sorbent towards arsenate (steep equilibrium isotherms) and its fast adsorption kinetics. Because of the mesoporous (as determined by N 2 adsorption and SEM) and layered (as determined by XRD and FTIR) structure of the ion-exchange material as well as the abundance of anion exchange sites (as determined by XPS and potentiometric titration) on its surface the material demonstrated very competitive (or very high) removal capacity towards other targeted anions, including fluoride, bromide, bromate, selenate, selenite, and borate. © 2011 IWA Publishing.

Charge exchange processes involving iron ions

International Nuclear Information System (INIS)

Phaneuf, R.A.

1985-01-01

A review and evaluation is given of the experimental data which are available for charge exchange processes involving iron ions and neutral H, H 2 and He. Appropriate scaling laws are presented, and their accuracy estimated for these systems. A bibliography is given of available data sources, as well as of useful data compilations and review articles. A procedure is recommended for providing single approximate formulae to the fusion community to describe total cross sections for electron capture by partially-stripped Fe/sup q+/ ions in collisions with H, H 2 and He, based on the scaling relationships suggested by Janev and Hvelplund

Solidification of ion exchange resin wastes

International Nuclear Information System (INIS)

1982-08-01

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

Separation of uranium from sodium carbonate - sodium bicarbonate eluate by ion exchange method

Energy Technology Data Exchange (ETDEWEB)

Sakane, Kohji; Hirotsu, Takahiro; Fujii, Ayako; Katoh, Shunsaku; Sugasaka, Kazuhiko (Government Industrial Research Inst., Shikoku, Takamatsu (Japan))

1982-09-01

The ion exchange method was used for separating uranium from the eluate (0.5 N Na/sub 2/CO/sub 3/-0.5 N NaHCO/sub 3/) that was obtained in the extraction process of uranium from natural sea water by using the titanium-activated carbon composite adsorbent. Uranium in the eluate containing 3 mg/1 uranium was adsorbed by ion exchange resin (Amberlite IRA-400), and was eluted with the eluant (5 % NaCl-0.5 % Na/sub 2/CO/sub 3/). The concentration ratio of uranium in the final concentrated-eluate became more than 20 times. The eluting solution to the adsorbent and the eluant to the resin could be repeatedly used in the desorption-ion exchange process. Sodium carbonate was consumed at the desorption step, and sodium bicarbonate was consumed at the ion exchange step. The concentration ratio of uranium was found to decrease as chloride ion in the eluate increased.

Separation of uranium from sodium carbonate-sodium bicarbonate eluate by ion exchange method

Energy Technology Data Exchange (ETDEWEB)

Sakane, K.; Hirotsu, T.; Fujii, A.; Katoh, S.; Sugasaka, K. (Government Industrial Research. Inst., Shikoku, Takamatsu (Japan))

1982-01-01

The ion exchange method was used for separating uranium from the eluate (0.5 N Na/sub 2/CO/sub 3/-0.5 N NaHCO/sub 3/) that was obtained in the extraction process of uranium from natural sea water by using the titanium-activated carbon composite adsorbent. Uranium in the eluate containing 3 mg/l uranium was adsorbed by ion exchange resin (Amberlite IRA-400), and was eluted with the eluent (5% NaCl-0.5% Na/sub 2/CO/sub 3/). The concentration ratio of uranium in the final concentrated-eluate became more than 20 times. The eluting solution to the adsorbent and the eluant to the resin could be repeatedly used in the desorption-ion exchange process. Sodium carbonate was consumed at the desorption step, and sodium bicarbonate was consumed at the ion exchange step. The concentration ratio of uranium was found to decrease as chloride ion in the eluate increased.

Charge exchange processes of high energy heavy ions channeled in crystals

International Nuclear Information System (INIS)

Andriamonje, S.; Dural, J.; Toulemonde, M.; Groeneveld, K.O.; Maier, R.; Quere, Y.

1990-01-01

The interaction of moving ions with single crystals is very sensitive to the orientation of the incident beam with respect to the crystalline directions of the target. The experiments show that high energy heavy ion channeling deeply modifies the slowing down and charge exchange processes. In this review, we describe the opportunity offered by channeling conditions to study the charge exchange processes. Some aspects of the charge exchange processes with high energy channeled heavy ions are selected from the extensive literature published over the past few years on this subject. Special attention is given to the work performed at the GANIL facility on the study of Radiative Electron Capture (REG), Electron Impact Ionisation (EII), and convoy electron emission. Finally we emphasize the interest of studying resonant charge exchange processes such as Resonant Coherent Excitation (RCE), Resonant Transfer and Excitation (RTE) or Dielectronic Recombination (DR) and the recently proposed Nuclear Excitation by Electron Capture (NEEC)

Synthesis, Characterization and Ion Exchange Properties of a New Composite of Inorganic Ion Exchanger： Polyacrylonitrile Cerium（IV） Molybdophosphate%Synthesis, Characterization and Ion Exchange Properties of a New Composite of Inorganic Ion Exchanger： Polyacrylonitrile Cerium（IV） Molybdophosphate

Institute of Scientific and Technical Information of China (English)

Ahmadi, Seyed Javad; Yavari, Ramin; Ashtari, Parviz＇; Gholipour, Vanik; Kamel, Leila; Rakhshandehru, Farokh

2012-01-01

In this work, the synthesis of the composite of cerium（IV） molybdophosphate （CMP） and polyacrylonitrile （PAN） was reported （CMP-PAN）. The material has been characterized by elemental and spectral （FT-IR）, X-ray and thermal （TGA） analysis. Also the size analysis of the composite was done by scanning electron microscopy （SEM）. Its chemical stability in acidic, basic and saline solutions and radiation stability up to 100 kGy total expose dose were assessed. Whereas the synthesized composite has ion exchange properties, its ion exchange capacity and behavior toward several metal ions were also investigated. Further, the distribution coefficients of the metal ions were calculated. Finally, the ability of the synthesized CMP-PAN composite for the decontamination of low level liquid waste （LLLW） was investigated.

Influence of ion bombardment induced patterning of exchange bias in pinned artificial ferrimagnets on the interlayer exchange coupling

Energy Technology Data Exchange (ETDEWEB)

Schmalhorst, Jan; Reiss, Guenter; Hoenik, V. [Thin Films and Nanostructures, Department of Physics, Univ. Bielefeld (Germany); Weis, Tanja; Engel, Dieter; Ehresmann, Arno [Institute of Physics and Center for Interdisciplinary Nanostructure Science and Technology, Kassel Univ. (Germany)

2007-07-01

Artificial ferrimagnets (AFi) have many applications as, e.g., pinned reference electrodes in magnetic tunnel junctions. It is known that the application of ion bombardment induced magnetic patterning with He ions on a single layer reference electrode of magnetic tunnel junctions is possible. For some applications a combination of ion bombardment induced magnetic patterning and artificial ferrimagnets as a reference electrode is desirable. The effect of ion bombardment induced magnetic patterning on pinned artificial ferrimagnets with a Ru interlayer which is frequently used in magnetic tunnel junctions as well as pinned AFis with a Cu interlayer has been tested. Special attention has been given to the question whether the antiferromagnetic interlayer exchange coupling can withstand the ion dose necessary to turn the exchange bias.

Equilibrium and kinetics studies of metal ion adsorption on dyed ...

African Journals Online (AJOL)

GREGO

2007-04-02

Apr 2, 2007 ... Initial concentration of Cu(II) ions = 20 mg/l, adsorbent dose = 1.0 g. Table 2 Experiment Data of ... diffusivity of the metal ion would be independent of the extent of sorption .... exchange and adsorption. Equilibrium parameter.

Possibility of ion-exchange column studies using stabilised montmorillonite-H aggregates

International Nuclear Information System (INIS)

Platzer, R.; Bittel, R.

1959-01-01

The conditions necessary for obtaining stable aggregates of montmorillonite-H, prepared without addition of organic flocculant, is discussed. These aggregates possess the same general ion-exchange properties as montmorillonite-H suspensions, about which many papers have been written. Their insolubility and their stable physical form enable them to be used in columns in exactly the same way as the usual organic ion exchangers. The examples of cation fixation and separation described in this report emphasize the similarities between the properties of this exchanger and those of organic cation-exchange resins, and open up possibilities for the extrapolation of the many investigations carried out on organic exchangers to mineral exchangers of this type. Amongst the essential differences to be remarked, we have shown that the properties of physical stability and chemical exchange remain the same at temperatures up to 300 deg. C, to a first approximation, under very intense γ irradiation. (author) [fr

The mechanism of diffusion and ionic transport of alkali metal ions in the particles of tin(IV) antimonate

International Nuclear Information System (INIS)

El-Naggar, I.M.; El-Absy, M.A.; Aly, S.I.; Atomic Energy Establishment, Cairo

1992-01-01

The kinetics of exchange Li + , Na + , K + and Cs + ions of tin(IV) antimonate with H + form was studied under particle-diffusion-control conditions at different temperatures. The value of activation energy, diffusion coefficient and entropy of activation increase with the ionic mobilities and radii, and decrease with the hydration energy of the alkali metal ions. On the basis of the kinetic parameters, the exchange of alkali metal ions occurs in the unhydrated form. (author). 29 refs.; 4 figs.; 2 tabs

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

Science.gov (United States)

Kreuer, Klaus-Dieter; Jannasch, Patric

2018-01-01

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

Kinetic and mechanistic evaluation of tetrahydroborate ion electro-oxidation at polycrystalline gold

International Nuclear Information System (INIS)

Iotov, Philip I.; Kalcheva, Sasha V.; Bond, Alan M.

2009-01-01

The anodic oxidation of tetrahydroborate ion is studied in NaOH at stationary and rotating polycrystalline Au disk electrodes. Linear sweep and cyclic voltammetry are applied varying the scan and rotation rate from 0.005 to 51.200 V s -1 and from 52.3 to 314.1 rad s -1 , correspondingly. The effects of variation of BH 4 - and NaOH concentrations as well as of the potential limits of the ranges studied have been initially followed. Most of the experiments have been carried out with 10.9 mM NaBH 4 in 1.04 M NaOH at 293 K in the potential range from -1.300 to 0.900 V (vs. Ag/AgCl). It is found that 6 electrons are exchanged in the overall oxidation transformation. The kinetic analysis of the processes determining the two anodic peaks recorded under static conditions at scan rates lower than 0.500 V s -1 shows that 1.4 electrons are exchanged in the potential range of the first one (at ca -0.5 V), while the rate of the second one (at ca +0.3 V) is determined by a quasi-reversible 1-electron transfer reaction. A kinetic evidence for the participation of surface bound intermediates in the electro-oxidation process is provided. Two additional well outlined anodic peaks are recorded in the aforementioned potential range under specific experimental conditions. A quasi-8 electron mechanism involving four oxidation and hydrolysis steps is advanced to explain the experimental results. It accounts for the involvement of borohydride oxidation species and the Au + /Au 3+ mediator couple.

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

Science.gov (United States)

Brooker, Robert Paul; Mohajeri, Nahid

2016-01-05

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